US3504490A - Light sensitive apparatus for preventing flameout in combustion engines - Google Patents

Description

April 7, 1970 R. I.. KLAMM 3,504,490

LIGHT SENSITIVE APPARATUS FOR PREVENTING FLAMEOUT IN COMBUSTION ENGINES Filed Feb. 20, 1968 /0/ /f /00 f f x- FLI P /07 FLIP FLIP FLIF LFLOP FLoP IFLoP E V *J wf United States Patent O U.S. Cl. 60-39.09 16 Claims ABSTRACT F THE DISCLOSURE An elongated bundle of liber optics has one end thereof disposed in visual communication with the interior of the housing of a reaction-type combustion engine, and has the other end thereof disposed in visual communication with a light-sensitive element which can respond to light having wavelengths within a narrow range; and that light-sensitive element will act, whenever the light from the flames within that housing falls below the range of wavelengths to which that light-sensitive element responds, to actuate the ignition-initiating system of that engine. Thereafter, that ignition-initiating system will then be kept actuated for a predetermined length of time by a timer to avoid a ameout of that engine.

This invention relates to improvements in control systems. More particularly, this invention relates to improvements in control systems, for reaction-type cornbustion engines, which are intended to prevent flameouts of those engines.

It is, therefore, an object of the present invention to provide an improved control system, for a reaction-type combustion engine, which can prevent flameouts of that engine.

A flameout of a reaction-type combustion engine can be extremely serious; and hence it would be desirable to provide a control system which could prevent such ameoutsf Flameouts can occur in a reaction-type combustion engine when the fuel-air ratio of that engine is changed rapidly or to an undue extent, can occur in response to transient reductions in the amount of ail owing into that engine, can occur in response to anomentary interruptions in the flow of fuel, can occur when the exhaust products of rockets or other ordnance devices, which are tired adjacent the intake of that engine, enter that intake, and can occur when hail or sleet or heavy rain is drawn into the intake of that engine; but ilameouts can be prevented if the ignition-initiating system of that engine is actuated, and then is kept actuated for a predetermined length of time, before a ameout actually occurs. Consequently, it would be desirable to provide a control system which could sense the development of incipient ameouts in a reactiontype combustion engine, and which could automatically actuate the ignition-initiating system of that engine before ameouts could actually occur. The present invention provides such a control system; and that controlsystem has a light-sensitive element which is disposed in visual communication with the interior of the housing of a reaction-type combustion engine by means of an elongated bundle of fiber optics and which is responsive to light having wavelengths within a narrow range. As soon as the light from the flames within that engine falls below the range of wavelengths to which the light-sensitive element responds, that light-sensitive element will cause the ignition-initiating system of that engine to become actuated, and also will cause a timing circuit to keep that ignition-initiating system active for a predetermined length of time. That predetermined length of time will be long enough to encompass any period 3,504,490 Patented Apr. 7, 1970 of time during which a transient condition could cause a flameoutj and thus should be long enough to enable the reaction-type combustion engine to continue to operate without experiencing an actual ilanieoutf It is, therefore, an object of the present invention to provide a control system which has a light-sensitive element disposed in visual communication with the interior of the housing of a reaction-type combustion engine by means of an elongated bundle of iiber optics, which senses a relatively narrow range of light wavelengths, and which acts whenever the light from the flame within that housing falls below that range to actuate the ignition-initiating system of that engine, and also to cause a timer to keep that ignition-initiating system actuated for a predetermined length of time.

Other and further objects and advantages of the present invention should become apparent from an examination of the dra-wing and accompanying description.

In the drawing and accompanying description a preferred embodiment of the present invention is shown and described but it is to be understood that the drawing and accompanying description are for the purpose of illustration only and do not limit the invention and that the invention will be deed by the appended claims.

In the drawing,

FIG. 1 is an elevational view showing a reaction-type combustion engine with which the control system provided by the present invention is used,

FIG. 2 is a sectional view, on a larger scale, of part of the reaction-type combustion engine of lFIG. 1, plus a block-type showing of the lter, light-sensitive element, sensing circuit, timing network, display-type counter, and elongated bundle of liber optics used with that engine,

FIG. 3 is a diagram of the sensing circuit of the control system provided by the present invention, and

FIG. 4 is a circuit diagram of the timing network of that control system.

COMPONENTS OF CONTROL SYSTEM Referring to the drawing in detail, the numeral 20 generally denotes a reaction-type combustion engine as, for example, a jet engine for an aircraft. The housing of that engine is denoted in FIG. 2 by the numeral 19; and that housing has an opening 22 therein which has an internally-threaded boss 26 extending outwardly therefrom. The opening 22 is in register with a section of the burner casing 21 of the engine, as shown particularly by FIG. 2. A second opening 24 is provided in the housing 19, and the spark plug 25 of the ignition-initiating system of the engine 20 is mounted within that second opening.

The numeral 28 denotes an externally-threaded, hollow plug which has an outwardly-directed annular ange 29 thereon intermediate the ends thereof, and which has an inwardly-directed annular ange 27 at the inner end thereof. The external threads on the plug 28 will mate with the internal thread of the boss 26, so that plug can be solidly held within that boss. The outwardly-directed annular flange 29 on that plug can abut the outer end of the boss 26 to limit the extent to which that plug can telescope within that boss.

The numeral 34 denotes a window which is disposed within the inner end of the externally-threaded plug 28; and the diameter of the major portion of that window is larger than the inner diameter of the inwardly-directed annular flange 27. As a result, that inwardly-directed annular flange will keep the window 34 from falling, or being drawn, out of the externally-threaded plug 28. That window has a smaller diameter end portion 37 which extends through the opening defined by the inwardly-directed annular flange 27 and which extends inwardly beyond the inner end of the externally-threaded plug 28. That smaller diameter end portion is generally spherical in conguration; and it will be located in the fast-moving body of relatively-cool compressed air that continually ows between the exterior of the burner casing 21 and the interior of the housing 19. That fast-moving body of relatively-cool compressed air will keep the smaller diameter end portion 37 of the window 34 cool; and, importantly, it will keep dirt, dust and other foreign matter from coming to rest on that smaller diameter end portion. As a result, the window 34 will always be able to receive and transmit the light which will pass outwardly through the openings 23 in the burner casing 21 from the flames within that burner casing. The window 34 must be made from a material which is transparent to the wave lengths of light which are to be monitored, and it must be made of a material which will not soften or melt at the temperatures to which the housing 19 will be elevated; and one material that has been found to be very useful is quartz. A washer 35 is disposed immediately adjacent the outer face of the window 34; and a threaded washer 36 is held in intimate engagement with the outer face of the washer 35 by an internal thread within the externally-threaded plug 28. The threaded washer 36 will coact with the washer 35 to force the large diameter portion of the window 34 solidly against the inwardly-directed annular ange 27 at the inner end of the externally-threaded plug 28.

The numeral 30 denotes an elongated bundle of liber optics which has one end thereof telescoped into the externally-threaded plug 28, and which has the other end thereof secured to a filter 40 that is intended to pass only the light within a given range of wavelengths. ln one preferred embodiment of the present invention, that bundle of fiber optics is eXi-ble, is seventy-two inches long, is one-eighth of an inch in diameter, and is encased within a helically-wound, flexible, metal, protective sheath. A coupling y.32 is secured to the upper end of the helicallywound, llexible, metal, protective sheath for the elongated bundle 30 of iiber optics, as that elongated bundle is viewed in FIG. 2; and that coupling telescopes over the outer end of the externally-threaded plug 28 to hold the upper end of that bundle in register with the opening in the threaded Washer 36. The coupling 32 will provide a Sulliciently intimate engagement between itself and the externally-threaded plug 28 to prevent accidental separation of the bundle 30 of liber optics from that plug. The elongated bundle 30 of fiber optics is long enough to permit the housing 38, which encases the light-sensitive element 42, the filter 40, the sensing circuit 43, and the timing network 44 of the control system, to be located adjacent the air inlet of the engine 20, and thus wholly away from the heat of the burner section of that engine. That elongated bundle is exible enough to withstand the vibrations which will `be imparted to it during the opera tion of the reaction-type combustion engine 20. Further, that elongated bundle will have suticient resistance to heat to enable that bundle to withstand the relatively high temperatures to which the boss 26 and the externallythreaded plug 28 will be elevated by the combustion occurring within the burner casing of the engine The lilter 40 will pass light having wavelengths in the range to which the light-sensitive element 42 can respond; and, in one preferred embodiment of control system provided by the present invention, that light-sensitive element is an LS400 silicon planar photo diode of the Texas Instrument Company. Such a light-sensitive element is desirable because it has a high degree of sensitivity to light having wave lengths in the range of four-tenths to one and one-tenth microns. That light-sensitive element can detect energy levels as low as one hundredth of a milliwatt per square centimeter of surface area.

The components and connections of the sensing system 43 of FIG. 2 are shown in FIG. 3; and the numerals 46 and 48 denote P-channel metal oxide silicon field effect transistors. Those eld eiect transistors are designed for enhancement mode operation; and they are diffused into one monolithic chip so they can `be closely matched and so they will provide the same response to changes in ternperature. The sources of those eld eiect transistors are connected together by a junction 56; and that junction is connected to a source of positive fteen volts by a resistor 54, a junction 50, and a conductor 51. The drain of he eld eiect transistor 46 is connected to ground by a junction 64 and a resistor 66; and the drain of the lield eiiect transistor 48 is connected to ground by a junction 68 and a resistor 7'0. A resistor 58, a resistor 72, and an adjustable resistor 74 are connected between the junction 50 and ground; and a junction 60 between the resistors 58 and 72 is connected to the gate of the field effect transistor 46 to apply a positive bias to that gate. The light-sensing element 42 and a resistor 76 are connected between the junction 50 and ground by junctions 52 and 62; and that light-sensitive element and that resistor will constitute a voltage divider which will apply a positive bias to the gate of the field effect transistor 48.

The numeral 78 denotes a differential voltage comparator; and that differential voltage comparator preferably is an integrated circuit formed on a silicon chip. The input 77 of that dierential voltage comparator ampliiier is the inverting input; and it is connected directly to the junction 68. The input 81 of that differential voltage comparator is the noninverting input; and it is connected to the junction 64 by a junction 82. The positive voltage input of the dilerential voltage comparator 78 is connected to the junction S0 by the junction 52, the ground input is connected directly to ground, and the remaining input is connected to a source of positive five volts by a conductor 79. The output of the diierential voltage comparator 78 is connected to the noninverting input 81 by a junction 86, a resistor 84, and the junction 82.

An NPN transistor 88 has the base thereof connected to the output of the differential voltage comparator 78 by the junction 86, a Zener diode 90, a resistor 92, and a junction 94; and that base is spaced from ground by a resistor 93 which is connected between the junction 94 and ground. The emitter of transistor 88 is connected directly to ground; and the collector of that transistor is connected to a source of positive ve volts by a junction 95, a resistor 96, and a terminal 97. That collector also is connected to the input of a Nand gate 98; and the output of that Nand gate is connected to the timing network 44 by a conductor 100.

The components and connections of the timing network 44 of FIG. 2 are. shown in FIG. 4; and the numeral 102 denotes a clocked J-K flip-flop diode transistor integrated circuit. The numerals 142, 144, 146, 151, 152, 154 and 156 denote further clocked I-K flip-flop diode transistor integrated circuits. The conductor 100 connects the output of the Nand gate 98 of FIG. 3 to the clock input 101 of the flip-flop 102, and the set input of that flip-flop is connected directly to ground. The Q output of flip-flop 102 is denoted by the numeral 103, and it is connected to the direct set inputs of the ipflops 142, 144 and 146 by two or more of the junctions 104, 148 and 150. That output also is connected to a display-type counter 176 and to the ignition-initiating system 184 of the engine 20 by the junction 104, a conductor 105, and a junction 177, as shown by FIG. 2. The Q output 107 of the pi-op 102 is directly co-nnected to the input of a Nand gate 158; and the direct set input 109 of that ip-op is connected to the output of a Nand gate 168 by a junction 166. That junction, and hence the input of that Nand gate and the direct set input 109, are spaced from ground by a capacitor 170.

The Nand gates 98, 158 and 168 preferably are parts of a triple three-input Nand gate formed on a monolithic chip. However, only one of the three inputs of Nand gate 98 is used; and, similarly, only one of the three inputs of Nand gate 158 is used. The output of the Nand gate 158 is connected to thedirect set inputs of the dip- Hops 151, 152, 154 and 156 by one or more of junctions 160, 162 and 164.

The numeral 136 denotes a unijunction transistor; and the base-two of that unijunction transistor is connected to a source of positive fifteen volts by a resistor 138, a junction 124 and a terminal 126. The base-one of that unijunction transistor is connected to ground by a junction 139 and a resistor 140. A resistor 122, an adjustable resistor 128, a resistor 130, and a capacitor 134 are connected between the junction 124 and ground; and a junction 132 between resistor 130 and capacitor 134 is connected directly to the emitter of the unijunction transistor 136. That unijunction transistor, that capacitor, resistors 122, 130, 138 and 140, and adjustable resistor 128 constitute a relaxation oscillator.

The junction 139 is directly connected to the clock input of the flip-hop 142; and the 'Q output of that flipflop is directly connected to the clock input of the ip-op 144. The Q output of the latter ip-op is directly connected to the clock input of the fiip-tiop 146. The output of the ip-op 146 is directly connected to the clock input of ip-flop 156, and the output of flip-flop 156 is directly connected to the clock input of ip-op 154. The output of ip-op 154 is connected to the clock input of flip-flop 152 and to the lower input of Nand gate 168 by a junction 174. The output of flip-flop 152 is connected to the clock input of tiip-tiop 151 and to the middle input of Nand gate 168 by a junction 172; and the output of flipflop 151 is directly connected to the upper input of that Nand gate. The ignition-initiating control system 184 is connected to the spark plug 25 by conductors 182, as shown particularly by FIG. l.

The flip-flop 102 is a master-slave, type K, integrated circuit flip-flop; and hence that flip-flop will store information in the master stage thereof whenever the voltage at the clock input 101 thereof is high, and will then transfer that information tothe slave stage thereof when that voltage is low. Whenever a low votage is applied to the direct set input 109 of that iiip-op, that direct set input will dominate the other inputs of that hip-flop and will make the Q output 107 of that hip-flop high The set input of that flip-flop is grounded, and hence the voltage at that input always is low; and that low set input voltage will make the Q output go low when the voltage at the clock input 101 goes low.

The flip- flops 142, 144, 146, 151, 152, 154 and 156 are internally connected in the l K mode; and hence those flip-flops will change state on the negative-going edges of the pulses applied to the clock inputs thereof-if no input is being applied to the direct set bottom inputs of these tiip-ops. The set inputs and the Q outputs of the flip- ops 142, 144, 146, 151, 152, 154 and 156 are not used.

OPERATION OF CONTROL SYSTEM WHEN REACTION-TYPE COMBUSTION ENGINE IS OPERATING NORMALLY When the operator of the reaction-type combustion engine closes the switch that supplies electric power to that engine, that switch or another switch or a relay will supply power to the sensing circuit 43 and to the timing network 44. Power will continue to be supplied to that sensing circuit and to that timing network as long as power is supplied to the engine 20; and hence that sensing circuit and that timing network will always be ready to actuate the ignition-initiating system 184 whenever an incipient ameout develops.

After the operator of the reaction-type combustion engine 20 has applied power to that engine, he will close a switch, not shown, which will actuate the ignitioninitiating system 184; and that ignition-initiating system will cause flames to develop in the burner casing 21 within the housing 19. After the reaction-type combustion engine 20 has started to operate in its intended fashion, the operator of that engine will permit that switch to reopen so the ignition-initiating system 184 can become inactive. Flames will continue to develop in the burner casing 21 within the housing 19; and the Window 34 will permit light from those ames to pass through the openings in the washers 35 and 36 to the bundle 30 of fiber optics. That bundle of fiber optics will conduct that light to the iilter 40 which will pass the portions of that light, which have wave lengths between fourteenths and one and one-tenth microns, to the light-sensitive element 42; and that light-sensitive element will respond to those portions of that light to eX- perience a sharp decrease in the resistance thereof.

At the instant the timing network 44 is connected to the source of power therefor, the voltages at one or more of the outputs of flip-flops 151., 152 and 154 will be low, and hence the Nand gate 168 will tend to apply a high voltage to the direct set input 109 of flipiiop 102. However, the capacitor 170 will require a nte time to charge up, and thus will initially hold that voltage down-thereby enabling the direct set input 109 to cause the voltage at the Q output 107 to be high long enough to enable the Nand gate 158 to apply a low signal to the direct set inputs of flipflops 151, 152, 154 and 156, and also enabling the direct set input 109 to cause the voltage at the Q output 103 to apply a low signal to the direct set inputs of the ip- ops 142, 144 and 146. As a result, each of the flip- flops 142, 144, 146, 151, 152, 154 and 156 will have a low signal applied to the direct set input thereof; and that signal will make the voltage at the output thereof low. Thereafter, the voltage at the Q output 107 will continue to be high and the voltage at the output l103 will continue to be low-and hence each of the flip- flops 142, 144, 146, 151, 152, 154 and 156 will continue to have a low signal applied to the direct set input thereof-until a signal is applied to the clock input 101 of the ip-op 102. l The unijunction transistor 136, the capacitor 134, .the resistors 122, 130, 138 and 140, and the adjustable Vresistor 128 will, as soon as the timing network 44 is -connected to the source of power therefor, cause that capacitor to charge up to the emitter peak point voltage of that unijunction transistor; and, thereupon, that uniljunction transistor will become conductive and will permit Athat capacitor to discharge through the emitter base-one circuit of that unijunction transistor and the resistor to ground. The resulting voltage pulse across that resistor `will not cause the iiip-iiop 142 to change state; because that ip-op, as well as the rest of the flip- flops 144, 146, 151, 152, 154 and 156 will continue t0 have a low voltage applied to the direct set terminal thereof, and thus will be unable to respond to any signals applied to the clock input thereof.

As soon as the capacitor 134 has become discharged, it will start charging again; and, when the voltage across that capacitor again reaches the emitter peak point voltage of the unijunction transistor 136, that unijunction transistor will become conductive and again permit the capacitor 134 to discharge through the resistor 140. Once again, however, the resulting voltage pulse across that resistor will be unable to cause the ip-flop 142 to change its state; because that flip-flop will continue to have a low voltage applied to the direct set input thereof.

The relaxation oscillator, which includes the unijunction transistor 136, the capacitor 134, the resistors 122, 130, 138 and 140, and the adjustable resistor 128, will develop voltage pulses across the resistor 140, and those voltage pulses will ybe applied to the clock input of the flip-flop 142, as long as the timing network is connected to the source of power therefore. In one preferred embodiment of the present invention, adjustment of the position of the movable contact of the adjustable resistor 128 will enable that relaxation oscillator to develop those voltage pulses at a rate between about one per second and about eleven per second.

The field effect transistors 46 and 48 of FIG. 3 are matched so they have substantially identical characteristics; and the resistors y66 and 70 are matched so they have substantially identical values of resistance. Because the sources of both of those field effect transistors are connected to the terminal 50 by the resistor 54, and because those field effect transistors and the resistors 66 and 70 are matched, those field effect transistors can provide a close comparison of the voltages applied to the gates thereof. The series-connected resistors 58 and 72 and adjustable resistor 74 will develop a substantially fixed voltage at the gate of the field effect transistor `46, whereas the series-connected light-sensitive element `42 and resistor 76 will develop a voltage at the gate of field effect transistor 48 that will be a function of the light, in the range of fourtenths through one and one-tenth microns, which impinges upon that light-sensitive element. In one preferred embodiment of the present invention, the resistance of resistor 58 is about twice the sum of the resistance of resistor 72 and the maximum resistance of adjustable resistor 74; and, when the reaction-type combustion engine is operating properly, the resistance of the light-sensitive element 42 will be considerably less than twice the resistance of resistor 7-6. Consequently, as long as the engine 20 is operating properly, the voltage at the gate of the field effect transistor 48 will be higher than the voltage at the gate of the field effect transistor 46j. and, because those f'leld effect transistors are P-channel metal oxide silicon transistors designed for enhancement mode operation, the amount of current flowing through the resistor 70 will be less than the amount of current flowing through the resistor 66. The resulting voltage at the inverting input 77 of the differential voltage comparator 78 will be less than the resulting voltage at the noninverting input 81 of that differential voltage comparator; and hence the voltage at the output of that differential voltage comparator will be high The Zener diode 90 will become conductive and will apply a positive signal to the base of transistor 88, thereby causing that transistor to become conductive at the saturation level; and the resulting low voltage at the input of Nand gate 98 will enable that Nand gate to apply a high voltage to the clock input 101 of the flip-flop 102. Because that flip-flop does not respond to positive signals at the clock input thereof, the voltage at the ouput of that flip-flop will continue to remain low.

As long as the reaction-type combustion engine operates properly, the flames in the burner casing 21 within the housing 19 will supply sufficient light, within the range of four-tenths to one and one-tenth microns, to the light-sensitive element 42 via the bundle 30 of fiber optics to enable the voltage at the gate of field effect transistor 48 to be higher than the voltage at the gate of field effect transistor 46; and hence the sensing circuit 43 will con tinue to apply a high voltage to the clock input of the flip-flop 102. That flip-flop will not respond to such a signal; and hence that flip-flop will not apply a high signal to the ignition-initiating system 184-and, for lack of such a signal, that ignition-initiating system will remain inactive. Also, the flip-flop 102 and the Nand gate 158 will continue to apply low voltages to the direct set inputs of the flip- flops 142, 144, 14'6, 151, 152, 154 and 156; and hence those flip-flops will not be able to respond to the voltage pulses which the relaxation oscil lator develops across the resistor 140.

The position of the movable contact of the adjustable resistor 74 will determine the minimum level of flame intensity which is needed to keep the voltage at the gate of field effect transistor 48 higher than the voltage at the gate of field effect transistor 46. Ordinarily, that movable contact will be set so the voltage at the gate of field effect transistor 48 will be higher than the voltage at the gate of fleld effect transistor 46 as long as the level of flame intensity equals or exceeds the level of flame intensity that is developed while the reaction-type combustion engine 20 is idlingj but will drop below the voltage at the gate of field effect transistor 46 whenever the level of flame intensity drops below the level of flame intensity developed while that engine is idling Such a setting will avoid needless and premature actuations of the ignition-initiat ing system 184, but will provide prompt actuation of that ignition-initiating system whenever such actuation is needed.

OPERATION OF CONTROL SYSTEM WHEN REAC- 'HON-TYPE COMBUSTION ENGINE FAILS TO OPERATE PROPERLY If the fuel-air ratio of the reaction-type combustion engine 20 is changed rapidly or to an undue extent, if a transient reduction in the amount of air flowing into that engine occurs, if a momentary interruption in the flow of fuel to that engine occurs, if excessive amounts of the exhaust products of rockets or other ordnance devices enter the intake of that engine, or if excessive amounts of hail, sleet or rain enter the intake of that engine, an incipient ameout develops, the intensity of the light, having wave lengths in the range of four-tenths to one and one-tenth microns, will decrease; and, if that intensity falls below the level of flame intensity that is developed while the reaction-type combustion engine 20 is idling, the resistance of the light-sensitive element 42 will increase to the point where the voltage at the gate of field effect transistor 48 will no longer exceed the volt age at the gate of field effect transistor 46. Thereupon, the reduced voltage at the inverting input 77 of the differ ential voltage comparator 78 will Cause the voltage at the output of that differential voltage comparator to drop below the Zener voltage of the Zener diode and, at such time, that Zener diode will be unable to cause current to continue to flow through the base-emitter circuit of the transistor 88. That transistor will then become nonconductive; and the resulting high voltage vat the input of Nand gate 98 will cause that Nand gate to apply a negative-going signal to the clock input 101 of the flip-flop 102. That flip-flopwill respond to that negative-going signal to eliminate the "high voltage at the Q output 107 thereof-thereby causing the Nand gate 158 to eliminate the low voltage which it had been maintaining at the direct set inputs of the flip- flops 151, 152, 154 and 156; and it will also respond to that negative-going signal to develop a high voltage at the output 103 thereofthereby actuating the ignition-imitating system 184 and the display-type counter 176, and also eliminating the low voltage which had been maintained at the direct set inputs of the flip- flops 142, 144 and 146. The total time required for the sensing system 43 and the flip-flop `102 to apply a high voltage to the ignition-initiating system 184 is quite short-being less than one-thousandth of a second; and hence that ignition-initiating system can supply power to the spark plug 25 via conductors 182 vbefore a flameout actually occurs. That spark plug will enable further fuel and air introduced into the reaction-type combustion engine 20 to burn and to provide the energy which that engine requires.

Once the low voltages at the direct set inputs of the flip- flops 142, 144, 146, 151, 152, 154 and 156 are eliminated, those flip-flops can respond to negative-going signals at the clock inputs thereof; and, almost immediately, the relaxation oscillator, which includes the unijunction transistor 136, the capacitor 134, the resistors 122, 130, 138 and 140, and the adjustable resistor 12S, will apply such a negative-going signal to the clock input of the flipflop 142. That flip-flop will respond to that negative-going signal to develop a positive-going signal at the output thereof, but the clock" input of the flip-flop 144 will not respond to such a signal. However,

when that relaxation oscillator supplies a further negative-going signal, ilip-tlop 142 will respond to that negative-going lsignal to develop a negative-going signal at the Q output thereof; and the llip-op 144 will respond to that negative-going signal. The flipops 142, 144, 146, 156, 154, 152, and 151 are connected as a seven digit, rippple carry, binary counter, with the Q output of each llip-op thereof serving as the clock for the next-succeeding ilip-op. The relaxation oscillator will continuously supply signals to the clock input of the flip-flop 102; and, as long as the voltage at the direct set input of that flip-flop is high, that ilip-op will respond to every second signal to cause the output voltage thereof to go low. The flip op 144 will respond to every fourth signal, the flip-flop 146 will respond to every eighth signal, the ip-flop 156 will respond to every sixteenth signal, the flip-op 154 will respond to every thirty-second signal, and the flip-liep 152 will respond to every sixtyfourth signal from the relaxation oscillator to cause the output voltage thereof to go low. At the same time the negative-going trailing edge of the one hundred and twelfth signal from the relaxation oscillator is applied to the clock input of the flip-flop 142, the signals at the outputs of the ip- ops 154, 152 and 151 will all be high; and the Nand gate 168 will respond to the resulting high voltages at the three inputs thereof to apply a low voltage to the direct set input 109 of the ip-op 102. Thereupon, the voltage at the output 103 will become low-permitting the ignition-initiating system 184 to become inactive and causing the Hip- ops 142, 144 and 146 to reset-and the voltage at the Q output 107 will become high-causing the Nand gate 158 to reset the flip- Hops 151, 152, 154 and 156. All of this means that the seven digit, ripple carry, binary counter, which includes the ip- iiops 142, 144, 146, 156, 154, 152 and 151, will count to one hundred and twelve and then coact with Hip-flop 102 and Nand gate 158 to automatically reset itself; and, as that seven digit, ripple carry, binary counter resets itself, it will cause a low voltage to appear at the output 103 of the flip-flop 102 and thereby permit the ignition-initiating system 184 to become inactive.

The action of the control system, in actuating the ignition-initating system 184, is so rapid that it will usually occur before the operator of the reaction-type combustion engine 20 realizes that an actuation of that ignitioninitiating system was necessary. However, because it is advisable for that operator to know whenever an actuation of the ignition-initiating system 184 was necessary, the display-type counter 176 will be actuated each time the ignition-initiating system 184 is actuated; and that display-type counter will display the total number of actuations of the ignition-initiating system 184 which have occurred during any given period of operation of the reaction-type combustion engine 20. lf an appreciable number of actuations of the ignitioninitiating system 184 are caused, within a short period of time, by the control system of the present invention, the operator of the engine 20 should take whatever action he can to avoid any further need of actuations of that ignition-initiating system.

The action of the timing network 44 in resetting the flip-flop 102-and thus permitting the ignition-initiating system 184 to become inactive-after a predetermined period of time is desirable; because it will keep the spark plug 25 from burning outas it would do if the ignition-initiating system was operated continuously. However, that timing network will keep that ignition-initiating system actuated for a period of time which is long enough for any transient conditions, which caused the incipient ameout, to disappear. Even after the timing network 44 has permitted the ignition-initiating system 184 to become inactive, the operator of the reaction-type combustion engine 20 can actuate that ignition-initiating system. The control system of the present invention thus minimizes the need of manual actuation of the ignitioninitiating system 184 but does not prevent such manual actuation.

When the spark plug 25 helps re-establish the flames in the burner casing 21 within the housing 19, the window 34, the openings in the washers 35 and 36, the bundle 30 of fiber optics, and the lter 40 will enable the light-sensitive element 42 to see the light from those flames. That light will decrease the resistance of that light-sensitive element until the voltage at the gate of the field effect transistor 48 is again above the voltage at the gate of the field effect transistor 46; and, at such time, the voltage at the clock input 101 of Hip-flop 102 will be high. That high voltage will not cause that Hip-flop to change state; and hence that flip-dop will continue to have a high voltage at the output 103 thereof until the Nand gate 168 applies a low voltage to the direct set input 109 thereof. Thereafter, that flip-op' will develop a low voltage at the output 103 thereof and a high voltage at the Q output 107 thereof as long as the flame intensity equals or exceeds the ame intensity that is developed while the reaction-type combustion engine 20 is idling CONCLUSION The ilip-.op 102 will apply a signal to the direct set inputs of the iiip- ops 142, 144 and 146 which will make the voltages at the outputs of those tlip`ops low whenever the voltage at the output 103 goes from high to low. The power-supplying capability of the ip-op 102 will not be great enough to enable that iiiptiop to also apply signals to the direct set inputs of the flip- flops 151, 152, 154 and 156 which will make the voltages at the outputs of those ipdlops go from. high to low whenever the voltage at the output 103 goes from high to lowf However, the voltage at the Q output 107 will rise as the voltage at the output 103 falls; and the Nand gate 158 will respond to the high voltage at the input thereof to apply a low voltage to the direct set inputs of the `ilip- ops 151, 152, 154 and 156`thereby causing the outputs of those flip-flops to be 1ow. If a flip-flop` 102 were to be used which had sutlicient power to enable the voltage at the output 103 thereof to directly reset all ,of the flip- ops 142, 144,

146, 151, 152, 154 and 156, the Nand gate 158 could be eliminated.

The connecting of the outputs of the ip- ilops 151, 152 andv154 to the three inputs of the Nand gate 168 is desirable, because it enables the seven digit, ripple carry, binary counter to count to one hundred and twelve before that binary counter resets itself, In enabling that seven digit, ripple carry, binary counter to count to one hundred and twelve before it resets itself, the control system of the present invention utilizes a very high percentage of the capacity of that binary counter while minimizing the number of ilip-ilops which are needed to decode the counter-resetting number.

As the various Hip-flops of the seven digit, ripple carry, binary counter change state, false signals may tend to develop at the output of the Nand gate 168. It would be undesirable for any such false signals to be applied to the direct set input 109 of the ilip-flopl 102, because one or more of those false signals might reset that flip-flop prematurely. The capacitor will absorb any such false signals, and will thereby keep false signals which may tend to develop at the ouput of the Nand gate 168 from resetting the flip-flop 102.

In one preferred embodiment of the present invention, the movable contact of the adjustable resistor 74 was set so the sensing circuit 43 and the ip-op' 102 actuated the ignition-initiating system 184 whenever the intensity of the light from the flames in the burner casing 21 fell slightly below the level of intensity experienced whenever the reaction-type combustion engine is idling However, that movable contact can be set to cause that sensing circuit and that hip-flop to actuate that ignition-initiating system at any desired level of intensity of' the flames in the burner casing 21.

If an accident to the vehicle, in which the reaction-type combustion engine 20 is mounted, severed the bundle 30 of fiber optics, the sensing circuit 43 would actuate the ignition-initiating system 184. Similarly, if an open were to develop in the light-sensing element y42, or if any breakdown were to occur in any of the other components of the sensing circuit 43 which would cause the voltage at the clock input of flip-flop 102 to go low, the ignition-initiating circuit 184 would become actuated. The resulting fail safe operation of the control system is desirable, because it will enable that control system to provide protection for the operator of the reaction-type combustion engine even after that control system is unable to operate in normal fashion.

The filter 40 can be used to limit the wave lengths of light, which reach the light-sensitive element 4Z, to a specific range; and thus can enable the control system to respond to the intensities of light having just those wavelengths. Those wavelengths can be in the invisible as well as the visible range of light. For example, if it was desirable to have the light-sensitive element 42 respond to light having wavelengths in the infrared region, a light-sensitive element 42 would be selected which could respond to light having wavelengths in the infrared region and a filter 40 would be selected which would pass light having wevelengths in the infrared region but which would attenuate light having other wavelengths. On the other hand, if it was desirable to -keep the light-sensitive element 42 from responding to light having wavelengths in the infrared region, a filter 40 could be selected which would attenuate light having wavelengths in the infrared region. As a result, it should be apparent that the lightsensitive element 42- can be made to respond to light having any of the wavelengths in the fla-mes within the burner casing 21.

In at least one embodiment of the present invention, a filter 40* was not needed and was not used. The lightsensitive element 42 of that embodiment of control system was selected so it was sensitive to a range of light wavelength which included the range of wavelengths of the light developed by the flames within the burner casing 21; and that embodiment of control system operated quickly and effectively to actuate the ignition-initiating system 184 whenever the intensity of light having the said wave lengths fell below a given level.

The field effect transistors 46 and 48, the resistors 54, 58, 66', 70, 72 and 7-6, and the adjustable resistor 74 perform a treble function` Not only do they sense changes in the intensity of the light seen by the light-sensitive element 42, but they act as an impedance buffer between the high impedance of that light-sensitive element and the relatively low input impedance of the differential voltage comparator '78, and they shift the voltage levels to make the output voltage of that light-sensitive element compatible with the voltage at the input of that differential voltage comparator.

Whereas the drawing and accompanying description have shown and described a preferred embodiment of the present invention, it should be apparent to those skilled in the art that various changes may be made in the form of the invention without affecting the scope thereof.

What I claim is:

1. A control system for a combustion engine which develops a predetermined level of llame intensity whenever it is idling and which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit that is connected to the ignition-initiating system of said combustion engine and that is adapted to cause said ignition-initiating circuit to try to initiate ignition of fuel and air in said combustion engine,

said light-sensitive element and said sensing circuit responding to levels of ame intensity, within said combustion engine, at least as great as said predetermined level of flame intensity to permit Said ignition-initiating system to be inactive, whereby said light-sensitive element and said sensing circuit permit said ignition-initiating circuit to be inactive as long as said light-sensitive element sees levels of flame intensity, within said combustion engine, at least as great as said predetermined level of flame intensity,

said light-sensitive element and said sensing circuit responding to llames within said combustion engine which produce ame intensity levels below said predetermined level of flame intensity to cause said ignition-initiating circuit to try to initiate ignition of fuel and air in said combustion engine, whereby said light-sensitive element and said sensing circuit automatically cause said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine whenever said light-sensitive element sees a ame within said combustion engine but fails to see said predetermined level of llame intensity,

said light-sensitive element and said sensing circuit being adapted to anticipate and halt incipient flameouts by causing said ignition-initiating circuit to try to initiate ignition of fuel and air in said combustion engine while a flame still exists within said combustion engine.

2. A control system for a combustion engine which has a housing and a burner casing spaced inwardly of said housing and which comprises:

a light-sensitive element,

a sensing circuit that is connected to the ignition-initiating system of said combustion engine and that is adapted to cause said ignition-initiating circuit to try to initiate ignition of fuel and air in said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

a window mounted in said housing for said combustion engine,

said Window being close enough to said burner casing of said combustion engine to see light within said burner casing of said combustion engine but said window being spaced away from said burner casing of said combustion engine by an area through which air moves rapidly,

said window having a surface thereof directly contacted by said rapidly-moving air,

sa-id light-sensitive element being in visual communication with said window and said rapidly-moving air keeping said window clean to enable said window to maintain said light-sensitive element in visual communication with said burner casing of said combustion engine,

said rapidly-moving air also cooling said window, Whereby the temperature of said window will be essentially the same as the temperature of said housing.

3. A control system for a combustion engine which has a housing and a burner casing spaced inwardly of said housing and which comprises:

a light-sensitive element,

a sensing circuit that is connected to the ignition-initiating system of said combustion engine and that is adapted to cause said ignition-initiating circuit to try to initiate ignition of fuel and air in said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said comhustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

a mounting in said housing for said combustion engine which holds a window close enough to said burner casing of said combustion engine to see light within said combustion engine,

said light-sensitive element being in visual communication with said window and thus being in visual communication with light within said combustion engine,

said window having a portion thereof which lextends inwardly of said mounting and extends into an area through which air passes,

said air keeping said window clean to enable said window to maintain said light-sensitive element in visual communication with the interior of said combustion engine.

4. A control system for a combustion engine which has a housing and a burner casing spaced inwardly of said housing and which comprises:

a light-sensitive element,

a sensing circuit that is connected to the ignition-initiating system of said combustion engine and that is adapted to cause said ignition-initiating circuit to try to initiate ignition of fuel and air in said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said comhustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

a mounting in said housing for said combustion engine which holds a window close enough to said burner casing of said combustion engine to see light within said combustion engine,

said light-sensitive element being in visual communication with said window and thus being in visual communication with light within said combustion engine,

said window having a large diameter portion and a small diameter portion,

said mounting having an inwardly-directed annular ange which defines an opening through which said small diameter portion of said window extends but through which said large diameter portion of said window can not pass,

whereby said window is held in assembled relation with said mounting with said small diameter portion thereof extending through said opening.

5. A control system for a combustion engine which has a housing and a burner casing spaced inwardly of said housing and which comprises:

a light-sensitive element,

a sensing circuit that is connected to the ignition-initiating system of said combustion engine and that is adapted to cause said ignition-initiating system to tr to initiate ignition of fuel and air in said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light Within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

a mounting in said housing for said combustion engine which holds a window close enough to said burner casing of said combustion engine to see light within said combustion engine,

said light-sensitive element being in visual communication with said window and thus being in visual communication with light within said combustion engine', y

said window having a portion thereof which extends inwardly of said mounting and extends into an area through which air passes,

said air keeping said window clean to enable said window to maintain said light-sensitive element in visual communication with the interior of said combustion engine,

said window being transparent and being made of heatresistant material,

said inwardly-extending portion of said window having a configuration which minimizes the likelihood of dust, dirt or other foreign matter settling thereon and adhering thereto.

6. A control system for a combustion engine which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit connected to the ignition-initiating system of said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensiitve element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-imitating system to try to initiate ignition of fuel and air in said combustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

said light-sensitive element being sensitive to light having wave lengths within a narrow range,

said narrow range including light developed by a burning hydrocarbon fuel within said combustion engine whenever said combustion engine is operating normally but excluding light radiated by heated but essentially non-combustible parts of said combustion engine.

7. A control system `for a combustion engine as claimed in claim `6 wherein said light-sensitive element is sensitive to light having wave lengths within a range of four-tenths to one and one-tenth microns.

8. control system for a combustion engine which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit connected to the ignition-initiating system of said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of -fuel and air in said combustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

said sensing circuit having series-connected impedances that establish a reference voltage,

an impedance connected in series with said light-sensitive element to establish a second voltage that varies in response to the intensity of the light impinging upon said light-sensitive element, and

said sensing circuit responding to a predetermined difference between said reference voltage and said second voltage to cause said ignition-initiating system to try to initiate the ignition of fuel and air in said combustion engine.

9. A control system for a combustion engine which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit connected to the ignition-initiating system of said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine whenever said sensing circuit fails to see" said predetermined intensity of light within said combustion engine,

said sensing circuit applying a high voltage to a voltage-sensitive element of said control system whenever said combustion engine is operating normally but applying a low voltage to said voltage-sensitive element of said control system if an incipient flame out develops,

said sensing circuit also applying a low voltage to said voltage-sensitive element of said control system if said light-sensitive element is not in visual communication with said interior of said combustion engine or if improper operation of any part of said sensing circuit keeps said sensing circuit from applying said high voltage to said voltage-sensitive element of said control system,

whereby said control system will fail safe.

10. A control system lfor a combustion engine which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit connected to the ignition-initiating system of said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

said sensing circuit having means to establish a reference voltage,

an impedance connected in series with said light-sensitive element to establish a second voltage that varies in response to the intensity of the light impinging upon said light-sensitive element,

said sensing circuit responding to a predetermined difference between said reference voltage and said second voltage to cause said ignition-initiating system to try to initiate the ignition of fuel and air in said combustion engine, and

said sensing circuit having an impedance buffering and voltage-level-shifting means between said light-sensitive element and said voltage-sensitive element of said control system.

11. A control system for a combustion engine which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit connected to the ignition-initiating system of said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine Whenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

said sensing circuit having means to establish a reference voltage,

an impedance connected in series with said light-sensi tive element to establish a second voltage that varies in response to the intensity of the light impinging upon said light-sensitive element,

said sensing circuit responding to a predetermined difference said reference voltage and said second voltage to cause said ignition-initiating system to try to initiate the ignition of fuel and air in said combustion engine, and

said sensing circuit having a voltage-sensitive breakdown device that forces said sensing circuit to supply either a high voltage or a 10W voltage to said voltage-sensitive element of said control system.

12. A control system for a combustion engine Which comprises:

a light-sensitive element in visual communication with the interior of said combustion engine, and

a sensing circuit connected to the ignition-initiating system of said combustion engine,

said light-sensitive element and said sensing circuit permitting said ignition-initiating system to be inactive as long as said light-sensitive element sees a predetermined intensity of light -Within said combustion engine,

said light-sensitive element and said sensing circuit automatically causing said ignition-initiating system to try to initiate ignition of fuel and air in said combustion engine xwhenever said sensing circuit fails to see said predetermined intensity of light within said combustion engine,

a display-type counter which is actuated each time said ignition-initiating system is actuated.

13. In a control system, for use with a combustion engine which has a burner casing:

a light-sensitive element which is incapable of withstanding the temperatures attained by said burner casing of said combustion engine during the operation of said combustion engine,

said light-sensitive element being located remotely from said burner casing of said combustion engine and being located where it is relatively cool,

an elongated bundle of fiber optics interposed between said light-sensitive element and said burner casing of said combustion engine,

said elongated bundle of ber optics having one end thereof disposed to receive light from Within said burner casing and having the other end thereof disposed to direct light onto said light-sensitive element,

said elongated bundle of fiber optics conducting light, but virtually no heat, from said burner casing of said combustion engine to said light-sensitive element,

whereby said light-sensitive element is maintained in visual communication with the interior of said combustion engine but is protected from the heat of said burner casing of said internal combustion engine, and

a window mounted in the housing of said combustion engine,

said window being close enough to said burner casing of said combustion engine to see light -within said burner casing of said combustion engine,

said window being capable of withstanding the heat that is radiated toward it by said burner casing of said combustion engine,

said window being interposed between said burner casing of said combustion engine and that end of said elongated bundle of fiber optics which is adjacent to said burner casing of said combustion engine,

said Iwindow being spaced away from said burner casing of said combustion engine by an area through which air moves rapidly,

said window having a surface thereof directly contacted by said rapidly-moving air,

sai rapidly-moving air keeping said Window clean and also cooling said windo 14. In a control system, for use with a combustion engine which has a burner casing:

a light-sensitive element which is incapable of withstanding the temperatures attained by said burner casing of said combustion engine during the operation of said combustion engine,

said light-sensitive element being located remotely from said burner casing of said combustion engine and being located where it is relatively cool,

an elongated bundle of fiber optics interposed between said light-sensitive element and said burner casing of said combustion engine,

said elongated bundle of ber optics having one end thereof disposed to receive light from within said burner casing and having the other end thereof disposed to direct light onto said light-sensitive element,

said elongated bundle of fiber optics conducting light, but virtually no heat, from said burner casing of said combustion engine to said light-sensitive element,

whereby said light-sensitive element is maintained in visual communication with the interior of said cornbustion engine but is protected from the heat of said burner casing of said internal combustion engine, and

a window mounted in the housing of said combustion engine,

said window being close enough to said burner casing of said combustion engine to see light within said burner casing of said combustion engine,

said window being capable of withstanding the heat that is radiated toward it by said burner casing of said combustion engine,

said window being interposed between said burner casing of said combustion engine and that end of said elongated bundle of fiber optics which is adjacent to said burner casing of said combustion engine,

said window being spaced away from said burner casing of said combustion engine by an area through which air passes,

said air keeping said window clean to enable said window and said elongated bundle of fiber optics to maintain said light-sensitive element in visual communication with the interior of Said combustion engine.

415. In a control system, for use with a combustion engine which has a burner casing:

a light-sensitive element which is incapable of withstanding the temperatures attained by said burner casing of said combustion engine during the operation of said combustion engine,

said light-sensitive element being located remotely from said burner casing of said combustion engine and beng located where it is relatively cool,

an elongated bundle of ber optics interposed between said light-sensitive element and said burner casing of said combustion engine,

said elongated bundle of fiber optics having one end thereof disposed to receive light from within said burner casing and having the other end thereof disposed to direct light onto said light-sensitive element,

said elongated bundle of fiber optics conducting light, but virtually no heat, from said burner casing of said combustion engine to said light-sensitive element,

whereby said light-sensitive element is maintained in visual communication with the interior of said combustion engine but is protected (from the heat of said burner casing of said internal combustion engine, and

a window mounted in the housing of said combustion engine,

said window being close enough to said burner casing of said combustion engine to see light within said burner casing of said combustion engine,

Said window being capable of withstanding the heat that is radiated toward it by said burner casing of said combustion engine,

said window being interposed between said burner casing of said combustion engine and that end of said elongated bundle of fiber optics which is adjacent to said burner casing of said combustion engine, and

a mounting in said housing for said burner casing of said combustion engine which holds said window,

said window having a portion thereof which extends inwardly of said mounting and extends into an area through which air passes,

said air keeping said window clean to enable said window and said elongated bundle of fiber optics to maintain said light-sensitive element in visual communication with the interior of said combustion engine.

engine which has a burner casing:

a light-sensitive element which is incapable of withstanding the temperatures attained by said burner casing of said combustion engine during the operation of said combustion engine,

said light-sensitive element being located remotely from said burner casing of said combustion engine and being located where it is relatively cool,

an elongated bundle of ber optics interposed between said light-sensitive element and said burner casing of said combustion engine,

said elongated lbundle of liber optics having one end thereof disposed to receive light from within said burner casing and having the other end thereof disposed to direct light onto said light-sensitive element,

said elongated bundle of liber optics conducting light, but virtually no heat, from said burner casing of said combustion engine to said light-sensitive element,

whereby said light-sensitive element is maintained in visual communication with the interior of said combustion engine but is protected from the heat of said casing of said internal combustion engine, and

a window mounted in the housing of said combustion engine,

said window being close enough to said burner casing of said combustion engine to see light within said burner casing of said combustion engine,

said window being capable of withstanding the heat that is radiated toward it by said burner casing of said combustion engine,

said window being interposed between said burner casing of said combustion engine and that end of said elongated bundle of ber optics which is adjacent to said burner casing of said combustion engine, and

a mounting in said housing for said burner casing of said combustion engine which holds said window, 3,080,708 3/ 1963 Carr 431-79 said window having a large diameter portion and a 2,797,336 6/ 1957 Loft KSO-39.09

small diameter portion, 3,216,477 11/ 1965 Devine 431-79 said mounting having an inwardly-directed annular 3,364,971 1/1968 Hayes 431-79 ange which deines an opening through which said small diameter portion of said Window extends but 5 FOREIGN PATENTS through which said large diameter portion of said 660,178 10/1948 Great Britain window c :annot pass., i MARK M. NEWMAN, Primary Examiner whereby said window 1s heid m assembied relation with i said mounting with said small diameter portion l0 D- HART, Assistant Examlllel" thereof extending through said opening. v U S C1` X R 60-39.82; Z50-215; 431-79 References Cited UNrrED STATES PATENTS 2,804,131 s/1957 Amr 431-79 15

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