CA1170746A - Rotor measurement system using reflected load transmission - Google Patents
Rotor measurement system using reflected load transmissionInfo
- Publication number
- CA1170746A CA1170746A CA000374604A CA374604A CA1170746A CA 1170746 A CA1170746 A CA 1170746A CA 000374604 A CA000374604 A CA 000374604A CA 374604 A CA374604 A CA 374604A CA 1170746 A CA1170746 A CA 1170746A
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- CA
- Canada
- Prior art keywords
- signal
- load
- power supply
- power
- sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
- G08C17/02—Arrangements for transmitting signals characterised by the use of a wireless electrical link using a radio link
-
- G—PHYSICS
- G08—SIGNALLING
- G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
- G08C19/00—Electric signal transmission systems
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
Abstract
ROTOR MEASUREMENT SYSTEM
USING REFLECTED LOAD TRANSMISSION
Abstract of the Disclosure An apparatus is provided for obtaining data from sensor measurements made on a body moving rotationally with respect to a stationary observer. Reactive means couples radio frequency energy between an energy source fixed with respect to the observer and load varying means located on the moving body. The load variance is dependent upon measurement data provided by sensors located on the moving body. The variation in load is reflected back through the reactive coupling means to detection means which is fixed with respect to the observer The detection means operates to provide signals indicative of the measurement data provided by the sensors. The apparatus of the present invention may be easily retrofitted to rotational devices such as turbines, motors and generators to provide relevant, continuous, on-line measurements of important parameters associated with such rotating systems. These parameters include such measurements as temperature, pressure, strain and torque. Because of the reflected load nature of the formation transmission, only a single coupling is provided and this coupling serves to carry both power and information signals.
USING REFLECTED LOAD TRANSMISSION
Abstract of the Disclosure An apparatus is provided for obtaining data from sensor measurements made on a body moving rotationally with respect to a stationary observer. Reactive means couples radio frequency energy between an energy source fixed with respect to the observer and load varying means located on the moving body. The load variance is dependent upon measurement data provided by sensors located on the moving body. The variation in load is reflected back through the reactive coupling means to detection means which is fixed with respect to the observer The detection means operates to provide signals indicative of the measurement data provided by the sensors. The apparatus of the present invention may be easily retrofitted to rotational devices such as turbines, motors and generators to provide relevant, continuous, on-line measurements of important parameters associated with such rotating systems. These parameters include such measurements as temperature, pressure, strain and torque. Because of the reflected load nature of the formation transmission, only a single coupling is provided and this coupling serves to carry both power and information signals.
Description
7~i ROTOR MEASUREMENT SYSTEM
USING REFLECTED LOAD TR~NSMISS:tON
Background of the Invention This invention relates to an apparatus ~'or acquiring information from sensor measurements made on a body moving with respect to a stationary observer. More particularly, this invention relates to transmission means for acquiring tèmperature, pressure, torque, strain and the like sensor measurement data from a rotating object or device.
Since various rotating machines such asf turbines, :
~; ~ 10 motors and generators may oftten be operated under critically optimal or sfftressful condittfons, the need for accurately;
determining internal devicef conditions hfas increased. ~his greater need for sensor da~a generally occurs because o~
~- ~ two reasons. First, it is becoming increasingly desirable to operate var'ous machines at optimal or near optimal conditions and doing 90 requires greater in~ormation on various parameters associated with the rotating parts them-sel~es, In these situations~indirect or secondary data measurements~rom~peripheral sensors may not be sufficiently accurate, reliable or refIeffctive of~actual internal cond~tions,~Second,~ as~Yarious rotating devices are operated at lncreasingly higher load ratings, it becomes increasingly desirable tc~accurateIy determine system ~
conditions which~should~not be excaeded. Acff~urately sensing ~ theae conditions is~important~to~ensure that prctectLve~
control sy~stems~operate in a sufficie~tly adef~uate manner, such as~by~reducing or cutti~g o~f the power;to~the~syst~m prior to de~ice damage,~;F'urthermore,~the emergence~of digital and analcg control systems which are implemented 17MY-2819 .
on large-scale integrated circuit chips has greatly facilitated the ability to implement control systems having a large nun~er o input signal parameters.
. In the past, sensor information transmission between rotating and fixed parts has bean difficult and costly for several reasons. For example, a method of providing electrical power for the rotating sensors and transmission system must be proviaed. Battery power is inconvenient ~or such systems because of.the relatively short lives of chemical batteries~ Accordingly, other information and transmission systems have employed direct ~lip ring connections between the stationary and rotating parts, However, this is an inconvenient power transmission method which o~ten obscures the signal with noise. Further-more, slip ring connections are di~ficult to maintain, require regular attention and generally involve some degree of mechanical intarference. Because~of the problems associated with the brush connections for providing power to various rotating electronic data generating systems, : 20 others have employed reactive coupling to transfer the desired power. For example, transmission of desired power . may be a~fected by radio frequency electromagnetic coupling . ~ between a fixed coil and a coil rotating with the motor or -generator shaft. Howe~ex, because large motors and ganerators in particular often produce relatively high levels of radiated electromagnetic noise, conventional data acquisition systems may experience severe noise problems.
Additionally t it is not only necessary to provide power to - a rotating data acquisition system, it is also necessary, .:.:
; 30 in conventional systems, to provide a second independent : -2-.
!
~::L7~:'74t~
channel or the transmission of data signals from the rotating body to a relatively fixed observer. This is accomplished in conventional systems by the transmission of frequency or amplitude modulated carrier signals. More-over, these systems are also subject to noise problems andare unnecessarily complex and costly.
Summary of the Invention In accordance with a preferred embodiment of the present invention, an apparatus for obtaining data from sensor measurements made on a rotating body moving with respect to a stationary observer comprises reactiwe means ~or coupling a radio frequency energy source to load varying means on the moving body. The load i~ varied in accordance ~ with measurements provided by data sensors on the moving ; 15 body and the variation in load is reflected back through the reactive coupling means to fixed detector means which is responsive to load variations.
More particularly, in accordance with one preferred embod~ment of the present invention, voltage dependent sensors control a voltage controlled oscillator which switches the power supply for the oscillator between "on" and "off" states at frequencies dependent upon the measured parameters. The power supply is inductively coupled to a stationary coiL through which it receives radio frequency energy which it employs, after rectifi- -cation and filtering, if desired, to power the oscillator , .
and sensors. Thus, variations in load are reflected back through the inductive coupling coils to a detector which is responsive to these variations.
Accordinglyr i~ is an object of the present .
invention to provide data transmission means between a fixed observer and a body moving relative thereto. It is a further object of the present invention to provide such a data transmission apparatus which is easily retrofitted to existing machinery, is inexpensive, simple, and exhibits high noise immunity, particularly in environments employing relatively high power inductive machinery.
Brief Descript_on of the_Drawings The features of the invention believed to be novel are set forth with particularity in the appended ;claims. The invention itself, however, both as to organiza-tion and method o op~ration, together with ~urther ob;ects and advantages thereof, may best be understood by reference to the following descriptio~ taken in conjunation with the accompanying drawings in which:
FIG~RE 1 is a functional block diagram illustrating ~ the relationship between ~he element~ of the present invention.
- FIGURE 2 is a functional schematic diagram illustrating one embodiment of the present invention.
FIGU~E 3 is a perspecti~e view illustrating a t~pical environment in which the present invention may be employed.
Detailed Description of the I~vention Figure l illustrates a reflected load data trans-mission system for coupling information signals ~et~een fixed reference frame lO and moving referen~e frame 11.
~ine 19 delineates the fixed parts from the moving parts of the system. The apparatus of the present invention functions as follows. Radio frequency (RF) energy source :'j ` 18 supplies RF energy 26 to the reactive coupling means 16 "'' ' , -4--:
, ~i7~7~i which may comprise either a capacitive or an inductive coupling. Part of the reactive coupling means is fixed and the other part moves with reference frame 11. For present purposes, the motion of reference frame 11 can be thought of as being rotational. The reactive coupling means 16 provides radio frequency energy signals 24 to the load varying means 15. Load varying means 15 also receives signals 20 from sensor or sensors 12 and operates to vary the load in response to electrical output signals 20 from the sensor apparatus 12~ The vaxiation in load is reflected ~;~ back through the reactive coupling means as a time-varying load signal 23. It i9 ,to be part~cularly noted that in Figure 1 the wider arxows ~21~ 2~ and 26) represent power signals and the other arrow~ represent infoxmation signals.
~owever, it is to be parti~ularly noted with rQspect to es 23 a~nd 24, that they are shown here separately merely for conveying a functional understanding but that in fact, in the preferred embodiment of~the present inve~tion, , ~ ~ separate transmission channels for signal and power are unnecessary.~ The load variation signals 25 as seen ~rom the stationary reference,frame 10 are then supplied to detector 17 which produces el;ectrical signals 27 which are indicatiYe of the sensor measurements.
In particular load-~arying means 15 typically .
25- comprises a signal genera~ing means operating to proviae electrical signals 22'which depend on the data produced by sensor spparatus 12.~ The signal~means receives power;signals 21 from power~supply~means 14 and further interacts~with the powar supply means by~providing it with electrical signals 22 which operate-to switch~the power supply means on and off, . .:.:
~L~7~6 in accordance with information derived from the ~ensor signals 20. In this way then the load seen by the power supply means 14 varies in dependence upon sensor signals 20. It is this load variation which is reflected across the reactive coupling means 16 which also serves as a source of electrical energy to operate ~he power supply means 14 and the signal means 13 and if necessary the sensor apparatus 12. If necessary, the power supply means may also include a capacitive storage means which operates to provide electrical energy to the signal means 13 during thoss times in which electrical signals 22 have operated to remove the signal means as a load upon the power supply mean~.
Beaause the power supply load is itself switched, load ~ariation ~ignals are coupled back acros~ through the reacti~e coupling means to ~he stationary reference frame 10.
Accordingly~ only one reactiVe coupling means need be pro- ;
vided and the ahannel which suppLies~power signals to the rotating load varying means also acts to transmit sensor inormation to the detector. While load variation may assume a variety of dependencies, it is m~st convenient to have the load Yary in a binary, that is on and off-fashion. This resulting mode of operation produces digital transmission .
of information exhibitiny a nigh degree of noise immunity.
Figure 2 illustrates one embodIment of the present inYention in which the reactive coupling means comprises a :
pair of coiLs 33, one of which is fixed with respect to the stationary reference frame of t~e observer and the other of which is fixed~with respect to the rotating reference frame.
Radio freguency energy is transferred across coils 33 from RF power oscillator 18, This gF energy is received by switched ;
-6~
' .
~.~1.7~
powar supply 32 which preferably comprises a ~ull-wave rectifying bridge circuit, a filter capacitor connected across the output of the bridge circuit and a controlled.
electronic switch connected in series between the capacitor and the bridge so as to provide controlled dc power signals ~1 to voltage controlled oscillator 31 and amplifier 30.
Amplifier 30 receives infonmation signals rom sensors or transducers on the rotating reference frame and amplifies .them so as to drive the voltage-controlled oscillator 31.
This oscillator produces electrical signals ~ which operate the electronic switch to intermittently disconnect the dc current 21 demanded from the rectifiex. Thus~ there i~ a time-varying load dependency which is re~lected through coils 33 back to the ~ixed referenc~ frame. These "re~lected"
sig~als 25 may be conveniently detected by means of an envelope detector 36, The loaa vaxiations are then counted by counter 37 over a speci~ied period o~ time. This count is.a signal 27 which is dependent upon the sensor voltage applied to the voltage controlled oscillator 31. It is to be particularly noted, that in this embodiment of the present invention, the frequency of oscillator 31 is preferably chosen to be an order of magnitude or more below the frequency of oscillation of RF power oscillator 18.
The electrical circuits which are a~tached to fixed re~erence frame.10 are conveniently implemented using a single transistor circuit operating as an osci}l~tor whosr output drives a single transistor Class C amplifier. Class C.amplifier circuits are particularly suited for this purpose since their supply current varias directly with the load to which their output is connected.- The resulting swings in .
~7(;-~4~;
supply current to the Class C amplifier are then readily detected and counted. In this manner the inherent characteristics of the Class C ampliEier permit it to also function as an envelope detector.
Figure 3 illustrates a typical environment in which the present invention may be employed. Moreover, Figure 3 illustrates further advantages associated with the present invention. In this figure RF power oscillator 17 drives ~ixed inductive coil 16a which frequently comprises only a single turn of wire. However, in general, the number of turns employed depends on the coil diameter, the frequency used and impedance matching requiremen~. Coil 16a is electromagnetically coupled to coil 16b which rotates with mokor sha~t 60. Coil 16b as shown comprises approximately ~our turns of wire which are disposed in channel 57 formed in the periphery of an annular disc formed from disc halves SOa and SOb.. Portions 50a and 50b are each semiannular disc halves which are joined by nuts and bolts 52 as hown~ ~owever, any convenient mechanical means of attachment of the two semiannular portions may be employed, The method of attachment shown though, conveniently disposes nuts and bolts 52 in recesses Sl. For purposes of containing the circuitry of the present invention, recess 53 is provided in semiannular portion 50a. Also, conveniently provided is passage 56 through portion 50a for the passage of electrically conductive leads-from the coil 16b to the load-væying means 15 of the present invention. Likewise, passage 55 is provided for electri~ally conducti~e leads connecting the sensors (not shown) with thç load-varying means 15 of the present invention. The motor shaft 60 may also be conveniently, provided with passage 61 extending in both axial and radial directions so as to align with passage 55. Alternatively, the conductor leads to the sensors may be a~fixed to the circumferential portions o~
S the sha~t 60 by means of an adhesive or other attachment means. Provided in portion 50b is a similar recess 54 which may be employed to hold counterbalance masses to balance the mass of the circuits provided in recess 53, particularly if high-speed shaft rotation is expected~
The particularly beneicial advantage of the present invention is its ability to be employed in retro~it applications. That is to say, the present inventLon ls easily added to devices such as motors whose operating parameters need to be accurately determLned. Addition b~
the present invention to an existing installation is readily accomplished by affixing the desired sensors and extending their leads in a suitable manner to TOtating disc portions 50a and 50b containing the circuits o~ the present invention.
Variations in load, as determined by the sensors, are re1ected through coils 16b and 16a to load detector 18.
The semiannular portion 5Oa and 5 Ob provide a convenient means for attaching the present invention to the device to ' ~e monitored. Because these semiannular portions are designed to ~e mounted, a~d removed if later desired, coil 16b is provided with pin connectors 58 at the joints where the portions are fastened. Coil 16a may be supported by ' an~ convenient mechanical means, after which the oscillator 17 and detector 18 are connected and installa~ion is complete.- Thus, the pres~nt invention may not only be ' 30 employed on newer machinery but is also employable on _9_ ' , . ' .
. 1~7~-~7~1~
motors and generators whieh have been in the field for a number of years with no interference to normal operation.
Furthermore, no mechanical connection be~ween flxed and rotating parts is required.
In protective systems applications, the sensor data may be employed in a feedback arrangement to shut down the rotating device if specified limits are exceeded. For example, i the temperature on a motor rotor winding exceeds a preset value, the signals generated by the pres~snt invention may be employed to turn the motor of to prevent component damage.
While the presank in~ention has been described ` in terms of rotary motion, the lnvention is also applicable to other relative motio~ between the respective frames of .
reference. However, compensation may be required for those , , situations in which the relative motion produces variable degrees of electromagnetic coupling between the stationary and moving portions. Alternatively, couplings, such as long Goi1s, may be employed in certain situations to preserve the degree of e~ectromagnetic coupling desired.
Furthermore, while Figure 2 ~llustrates the partàcular case in which the power supply 32 is switched on and off according to the frequency content of electrical signals 22~ other mo~es of switching are possible. In particular, the sensor output voltages may be converted to digital signals which are employed to turn the power supply 32 on and off. ~owever, if this is done pro~ision shoul~
` ~e pro~ided for the case-in which a long string of zeros in the digital data output switches-the power supply to an off .. . .
~ 30 state for an excessive t~me ~eyond which capacitive or other .~., .
~;7~'~916 means are insufficient to power the sensors and digital converter circuits. However, many coding schemes are e~tant or the purpose of avoiding this problem. In particular, the digital data may be interspersed with S binary "ones" which would not turn off-the power supply.
Other binary coding schemes which are not capable of producing long strings of zeros or ones include bi-phase coding which employs mid-bit le~el changes and delay modulation coding. Additionally~, half-level codes in which the load is only reduced'may be employed to ensure adequate power to the rotating circuit components.
, From the above r it may be appreciated t'hat the present invention provides an apparatus ~or the transmission of sensor measurement data from a body moving relative to a ~ 15 fixed observer. Furthermore, this data transmission system ; ~ employs only a single channel, is highly immune to noise, may be constructed at-low cost and can be easily retrofitted to existing machinery with minimum effort. Moreover, the single channel may be shared to provide information from a plurality of sensors.
While the invention has been described in detail herein in accord with certain preferred embodiments thereof, many modifications and changes therein may be effected b~
~hose skilled-in the art. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the : ..
~ invention., ~.~
, ~ ~
USING REFLECTED LOAD TR~NSMISS:tON
Background of the Invention This invention relates to an apparatus ~'or acquiring information from sensor measurements made on a body moving with respect to a stationary observer. More particularly, this invention relates to transmission means for acquiring tèmperature, pressure, torque, strain and the like sensor measurement data from a rotating object or device.
Since various rotating machines such asf turbines, :
~; ~ 10 motors and generators may oftten be operated under critically optimal or sfftressful condittfons, the need for accurately;
determining internal devicef conditions hfas increased. ~his greater need for sensor da~a generally occurs because o~
~- ~ two reasons. First, it is becoming increasingly desirable to operate var'ous machines at optimal or near optimal conditions and doing 90 requires greater in~ormation on various parameters associated with the rotating parts them-sel~es, In these situations~indirect or secondary data measurements~rom~peripheral sensors may not be sufficiently accurate, reliable or refIeffctive of~actual internal cond~tions,~Second,~ as~Yarious rotating devices are operated at lncreasingly higher load ratings, it becomes increasingly desirable tc~accurateIy determine system ~
conditions which~should~not be excaeded. Acff~urately sensing ~ theae conditions is~important~to~ensure that prctectLve~
control sy~stems~operate in a sufficie~tly adef~uate manner, such as~by~reducing or cutti~g o~f the power;to~the~syst~m prior to de~ice damage,~;F'urthermore,~the emergence~of digital and analcg control systems which are implemented 17MY-2819 .
on large-scale integrated circuit chips has greatly facilitated the ability to implement control systems having a large nun~er o input signal parameters.
. In the past, sensor information transmission between rotating and fixed parts has bean difficult and costly for several reasons. For example, a method of providing electrical power for the rotating sensors and transmission system must be proviaed. Battery power is inconvenient ~or such systems because of.the relatively short lives of chemical batteries~ Accordingly, other information and transmission systems have employed direct ~lip ring connections between the stationary and rotating parts, However, this is an inconvenient power transmission method which o~ten obscures the signal with noise. Further-more, slip ring connections are di~ficult to maintain, require regular attention and generally involve some degree of mechanical intarference. Because~of the problems associated with the brush connections for providing power to various rotating electronic data generating systems, : 20 others have employed reactive coupling to transfer the desired power. For example, transmission of desired power . may be a~fected by radio frequency electromagnetic coupling . ~ between a fixed coil and a coil rotating with the motor or -generator shaft. Howe~ex, because large motors and ganerators in particular often produce relatively high levels of radiated electromagnetic noise, conventional data acquisition systems may experience severe noise problems.
Additionally t it is not only necessary to provide power to - a rotating data acquisition system, it is also necessary, .:.:
; 30 in conventional systems, to provide a second independent : -2-.
!
~::L7~:'74t~
channel or the transmission of data signals from the rotating body to a relatively fixed observer. This is accomplished in conventional systems by the transmission of frequency or amplitude modulated carrier signals. More-over, these systems are also subject to noise problems andare unnecessarily complex and costly.
Summary of the Invention In accordance with a preferred embodiment of the present invention, an apparatus for obtaining data from sensor measurements made on a rotating body moving with respect to a stationary observer comprises reactiwe means ~or coupling a radio frequency energy source to load varying means on the moving body. The load i~ varied in accordance ~ with measurements provided by data sensors on the moving ; 15 body and the variation in load is reflected back through the reactive coupling means to fixed detector means which is responsive to load variations.
More particularly, in accordance with one preferred embod~ment of the present invention, voltage dependent sensors control a voltage controlled oscillator which switches the power supply for the oscillator between "on" and "off" states at frequencies dependent upon the measured parameters. The power supply is inductively coupled to a stationary coiL through which it receives radio frequency energy which it employs, after rectifi- -cation and filtering, if desired, to power the oscillator , .
and sensors. Thus, variations in load are reflected back through the inductive coupling coils to a detector which is responsive to these variations.
Accordinglyr i~ is an object of the present .
invention to provide data transmission means between a fixed observer and a body moving relative thereto. It is a further object of the present invention to provide such a data transmission apparatus which is easily retrofitted to existing machinery, is inexpensive, simple, and exhibits high noise immunity, particularly in environments employing relatively high power inductive machinery.
Brief Descript_on of the_Drawings The features of the invention believed to be novel are set forth with particularity in the appended ;claims. The invention itself, however, both as to organiza-tion and method o op~ration, together with ~urther ob;ects and advantages thereof, may best be understood by reference to the following descriptio~ taken in conjunation with the accompanying drawings in which:
FIG~RE 1 is a functional block diagram illustrating ~ the relationship between ~he element~ of the present invention.
- FIGURE 2 is a functional schematic diagram illustrating one embodiment of the present invention.
FIGU~E 3 is a perspecti~e view illustrating a t~pical environment in which the present invention may be employed.
Detailed Description of the I~vention Figure l illustrates a reflected load data trans-mission system for coupling information signals ~et~een fixed reference frame lO and moving referen~e frame 11.
~ine 19 delineates the fixed parts from the moving parts of the system. The apparatus of the present invention functions as follows. Radio frequency (RF) energy source :'j ` 18 supplies RF energy 26 to the reactive coupling means 16 "'' ' , -4--:
, ~i7~7~i which may comprise either a capacitive or an inductive coupling. Part of the reactive coupling means is fixed and the other part moves with reference frame 11. For present purposes, the motion of reference frame 11 can be thought of as being rotational. The reactive coupling means 16 provides radio frequency energy signals 24 to the load varying means 15. Load varying means 15 also receives signals 20 from sensor or sensors 12 and operates to vary the load in response to electrical output signals 20 from the sensor apparatus 12~ The vaxiation in load is reflected ~;~ back through the reactive coupling means as a time-varying load signal 23. It i9 ,to be part~cularly noted that in Figure 1 the wider arxows ~21~ 2~ and 26) represent power signals and the other arrow~ represent infoxmation signals.
~owever, it is to be parti~ularly noted with rQspect to es 23 a~nd 24, that they are shown here separately merely for conveying a functional understanding but that in fact, in the preferred embodiment of~the present inve~tion, , ~ ~ separate transmission channels for signal and power are unnecessary.~ The load variation signals 25 as seen ~rom the stationary reference,frame 10 are then supplied to detector 17 which produces el;ectrical signals 27 which are indicatiYe of the sensor measurements.
In particular load-~arying means 15 typically .
25- comprises a signal genera~ing means operating to proviae electrical signals 22'which depend on the data produced by sensor spparatus 12.~ The signal~means receives power;signals 21 from power~supply~means 14 and further interacts~with the powar supply means by~providing it with electrical signals 22 which operate-to switch~the power supply means on and off, . .:.:
~L~7~6 in accordance with information derived from the ~ensor signals 20. In this way then the load seen by the power supply means 14 varies in dependence upon sensor signals 20. It is this load variation which is reflected across the reactive coupling means 16 which also serves as a source of electrical energy to operate ~he power supply means 14 and the signal means 13 and if necessary the sensor apparatus 12. If necessary, the power supply means may also include a capacitive storage means which operates to provide electrical energy to the signal means 13 during thoss times in which electrical signals 22 have operated to remove the signal means as a load upon the power supply mean~.
Beaause the power supply load is itself switched, load ~ariation ~ignals are coupled back acros~ through the reacti~e coupling means to ~he stationary reference frame 10.
Accordingly~ only one reactiVe coupling means need be pro- ;
vided and the ahannel which suppLies~power signals to the rotating load varying means also acts to transmit sensor inormation to the detector. While load variation may assume a variety of dependencies, it is m~st convenient to have the load Yary in a binary, that is on and off-fashion. This resulting mode of operation produces digital transmission .
of information exhibitiny a nigh degree of noise immunity.
Figure 2 illustrates one embodIment of the present inYention in which the reactive coupling means comprises a :
pair of coiLs 33, one of which is fixed with respect to the stationary reference frame of t~e observer and the other of which is fixed~with respect to the rotating reference frame.
Radio freguency energy is transferred across coils 33 from RF power oscillator 18, This gF energy is received by switched ;
-6~
' .
~.~1.7~
powar supply 32 which preferably comprises a ~ull-wave rectifying bridge circuit, a filter capacitor connected across the output of the bridge circuit and a controlled.
electronic switch connected in series between the capacitor and the bridge so as to provide controlled dc power signals ~1 to voltage controlled oscillator 31 and amplifier 30.
Amplifier 30 receives infonmation signals rom sensors or transducers on the rotating reference frame and amplifies .them so as to drive the voltage-controlled oscillator 31.
This oscillator produces electrical signals ~ which operate the electronic switch to intermittently disconnect the dc current 21 demanded from the rectifiex. Thus~ there i~ a time-varying load dependency which is re~lected through coils 33 back to the ~ixed referenc~ frame. These "re~lected"
sig~als 25 may be conveniently detected by means of an envelope detector 36, The loaa vaxiations are then counted by counter 37 over a speci~ied period o~ time. This count is.a signal 27 which is dependent upon the sensor voltage applied to the voltage controlled oscillator 31. It is to be particularly noted, that in this embodiment of the present invention, the frequency of oscillator 31 is preferably chosen to be an order of magnitude or more below the frequency of oscillation of RF power oscillator 18.
The electrical circuits which are a~tached to fixed re~erence frame.10 are conveniently implemented using a single transistor circuit operating as an osci}l~tor whosr output drives a single transistor Class C amplifier. Class C.amplifier circuits are particularly suited for this purpose since their supply current varias directly with the load to which their output is connected.- The resulting swings in .
~7(;-~4~;
supply current to the Class C amplifier are then readily detected and counted. In this manner the inherent characteristics of the Class C ampliEier permit it to also function as an envelope detector.
Figure 3 illustrates a typical environment in which the present invention may be employed. Moreover, Figure 3 illustrates further advantages associated with the present invention. In this figure RF power oscillator 17 drives ~ixed inductive coil 16a which frequently comprises only a single turn of wire. However, in general, the number of turns employed depends on the coil diameter, the frequency used and impedance matching requiremen~. Coil 16a is electromagnetically coupled to coil 16b which rotates with mokor sha~t 60. Coil 16b as shown comprises approximately ~our turns of wire which are disposed in channel 57 formed in the periphery of an annular disc formed from disc halves SOa and SOb.. Portions 50a and 50b are each semiannular disc halves which are joined by nuts and bolts 52 as hown~ ~owever, any convenient mechanical means of attachment of the two semiannular portions may be employed, The method of attachment shown though, conveniently disposes nuts and bolts 52 in recesses Sl. For purposes of containing the circuitry of the present invention, recess 53 is provided in semiannular portion 50a. Also, conveniently provided is passage 56 through portion 50a for the passage of electrically conductive leads-from the coil 16b to the load-væying means 15 of the present invention. Likewise, passage 55 is provided for electri~ally conducti~e leads connecting the sensors (not shown) with thç load-varying means 15 of the present invention. The motor shaft 60 may also be conveniently, provided with passage 61 extending in both axial and radial directions so as to align with passage 55. Alternatively, the conductor leads to the sensors may be a~fixed to the circumferential portions o~
S the sha~t 60 by means of an adhesive or other attachment means. Provided in portion 50b is a similar recess 54 which may be employed to hold counterbalance masses to balance the mass of the circuits provided in recess 53, particularly if high-speed shaft rotation is expected~
The particularly beneicial advantage of the present invention is its ability to be employed in retro~it applications. That is to say, the present inventLon ls easily added to devices such as motors whose operating parameters need to be accurately determLned. Addition b~
the present invention to an existing installation is readily accomplished by affixing the desired sensors and extending their leads in a suitable manner to TOtating disc portions 50a and 50b containing the circuits o~ the present invention.
Variations in load, as determined by the sensors, are re1ected through coils 16b and 16a to load detector 18.
The semiannular portion 5Oa and 5 Ob provide a convenient means for attaching the present invention to the device to ' ~e monitored. Because these semiannular portions are designed to ~e mounted, a~d removed if later desired, coil 16b is provided with pin connectors 58 at the joints where the portions are fastened. Coil 16a may be supported by ' an~ convenient mechanical means, after which the oscillator 17 and detector 18 are connected and installa~ion is complete.- Thus, the pres~nt invention may not only be ' 30 employed on newer machinery but is also employable on _9_ ' , . ' .
. 1~7~-~7~1~
motors and generators whieh have been in the field for a number of years with no interference to normal operation.
Furthermore, no mechanical connection be~ween flxed and rotating parts is required.
In protective systems applications, the sensor data may be employed in a feedback arrangement to shut down the rotating device if specified limits are exceeded. For example, i the temperature on a motor rotor winding exceeds a preset value, the signals generated by the pres~snt invention may be employed to turn the motor of to prevent component damage.
While the presank in~ention has been described ` in terms of rotary motion, the lnvention is also applicable to other relative motio~ between the respective frames of .
reference. However, compensation may be required for those , , situations in which the relative motion produces variable degrees of electromagnetic coupling between the stationary and moving portions. Alternatively, couplings, such as long Goi1s, may be employed in certain situations to preserve the degree of e~ectromagnetic coupling desired.
Furthermore, while Figure 2 ~llustrates the partàcular case in which the power supply 32 is switched on and off according to the frequency content of electrical signals 22~ other mo~es of switching are possible. In particular, the sensor output voltages may be converted to digital signals which are employed to turn the power supply 32 on and off. ~owever, if this is done pro~ision shoul~
` ~e pro~ided for the case-in which a long string of zeros in the digital data output switches-the power supply to an off .. . .
~ 30 state for an excessive t~me ~eyond which capacitive or other .~., .
~;7~'~916 means are insufficient to power the sensors and digital converter circuits. However, many coding schemes are e~tant or the purpose of avoiding this problem. In particular, the digital data may be interspersed with S binary "ones" which would not turn off-the power supply.
Other binary coding schemes which are not capable of producing long strings of zeros or ones include bi-phase coding which employs mid-bit le~el changes and delay modulation coding. Additionally~, half-level codes in which the load is only reduced'may be employed to ensure adequate power to the rotating circuit components.
, From the above r it may be appreciated t'hat the present invention provides an apparatus ~or the transmission of sensor measurement data from a body moving relative to a ~ 15 fixed observer. Furthermore, this data transmission system ; ~ employs only a single channel, is highly immune to noise, may be constructed at-low cost and can be easily retrofitted to existing machinery with minimum effort. Moreover, the single channel may be shared to provide information from a plurality of sensors.
While the invention has been described in detail herein in accord with certain preferred embodiments thereof, many modifications and changes therein may be effected b~
~hose skilled-in the art. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the : ..
~ invention., ~.~
, ~ ~
Claims (12)
1. Apparatus for obtaining physical measurement data from a body moving with respect to a stationary observer, comprising:
at least one sensor means disposed on said moving body for providing an output signal indicative of at least one such physical measurement;
an electrical energy source fixed with respect to said observer for supplying a radio frequency power signal;
means reactively coupling said radio frequency signal to said moving body for supplying operating power to an electrical load thereon;
means disposed on said moving body and responsive to said sensor output signal to effect corresponding changes in said electrical load causing amplitude variations in said radio frequency power signal;
detector means fixed with respect to said observer and responsive to said radio frequency power signal for detecting said amplitude variations due to said load changes to provide an-output signal characterizing said physical measurement, said load changes being reflected through said reactive coupling means.
at least one sensor means disposed on said moving body for providing an output signal indicative of at least one such physical measurement;
an electrical energy source fixed with respect to said observer for supplying a radio frequency power signal;
means reactively coupling said radio frequency signal to said moving body for supplying operating power to an electrical load thereon;
means disposed on said moving body and responsive to said sensor output signal to effect corresponding changes in said electrical load causing amplitude variations in said radio frequency power signal;
detector means fixed with respect to said observer and responsive to said radio frequency power signal for detecting said amplitude variations due to said load changes to provide an-output signal characterizing said physical measurement, said load changes being reflected through said reactive coupling means.
2. The apparatus of claim 1 wherein said reactive coupling means comprises an inductive coupler having a first inductive portion fixed with respect to said observer and a second inductive portion affixed to said moving body.
3. The apparatus of claim 1 wherein said means responsive to said sensor output signal includes:
a voltage controlled oscillator producing a signal whose frequency is proportional to said sensor signal, and a power supply forming part of said electrical load and responsive to be switched between an on condition and an off condition at a rate corresponding to the frequency of said oscillator signal.
a voltage controlled oscillator producing a signal whose frequency is proportional to said sensor signal, and a power supply forming part of said electrical load and responsive to be switched between an on condition and an off condition at a rate corresponding to the frequency of said oscillator signal.
4. The apparatus of claim 2 wherein said means responsive to said sensor output signal includes:
a voltage controlled oscillator producing a signal whose frequency is proportional to said sensor signal, and a power supply forming part of said electrical load and responsive to be switched between an on condition and an off condition at a rate corresponding to the frequency of said oscillator signal.
a voltage controlled oscillator producing a signal whose frequency is proportional to said sensor signal, and a power supply forming part of said electrical load and responsive to be switched between an on condition and an off condition at a rate corresponding to the frequency of said oscillator signal.
5. The apparatus of claim 3 wherein said detector means comprises:
an envelope detector providing a signal whose frequency is indicative of the switching rate of said power supply; and means providing a count of the frequency of said envelope detector signal, said count being indicative of said physical measurement.
an envelope detector providing a signal whose frequency is indicative of the switching rate of said power supply; and means providing a count of the frequency of said envelope detector signal, said count being indicative of said physical measurement.
6. The apparatus of claim 4 wherein said detector means comprises:
an envelope detector providing a signal whose frequency is indicative of the switching rate of said power supply; and means providing a count of the frequency of said envelope detector signal, said count being indicative of said physical measurement.
an envelope detector providing a signal whose frequency is indicative of the switching rate of said power supply; and means providing a count of the frequency of said envelope detector signal, said count being indicative of said physical measurement.
7. The apparatus of claim 5 wherein said power supply further includes storage means providing power to said electrical load at such time as said power supply is in said off condition.
8. The apparatus of claim 6 wherein said power supply further includes storage means providing power to said electrical load at such time as said power supply is in said off condition.
9. The apparatus of claim 7 wherein said electrical load includes said voltage controlled oscillator and said sensor means.
10. The apparatus of claim 8 wherein said electrical load includes said voltage controlled oscillator and said sensor means.
11. The apparatus of claim 9 further including an amplifier for amplifying said sensor output signal.
12. The apparatus of claim 10 further including an amplifier for amplifying said sensor output signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US06/137,422 US4354190A (en) | 1980-04-04 | 1980-04-04 | Rotor measurement system using reflected load transmission |
| US137,422 | 1980-04-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170746A true CA1170746A (en) | 1984-07-10 |
Family
ID=22477361
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000374604A Expired CA1170746A (en) | 1980-04-04 | 1981-04-03 | Rotor measurement system using reflected load transmission |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4354190A (en) |
| JP (1) | JPS56166597A (en) |
| KR (1) | KR850000268B1 (en) |
| BR (1) | BR8102069A (en) |
| CA (1) | CA1170746A (en) |
| ES (1) | ES8202144A1 (en) |
| IT (1) | IT8120798A0 (en) |
| MX (1) | MX150880A (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3029563C2 (en) * | 1980-08-05 | 1990-11-15 | Bayerische Motoren Werke AG, 8000 München | Transmission method for a variable measured value for the tire pressure of vehicle wheels |
| US4608550A (en) * | 1981-08-25 | 1986-08-26 | Aisin Seiki Kabushikikaisha | Electric signal transmission system on a road vehicle |
| US4446461A (en) * | 1981-11-02 | 1984-05-01 | United Technologies Corporation | Instrumentation for a rotary machine |
| US4758836A (en) * | 1983-06-20 | 1988-07-19 | Rockwell International Corporation | Inductive coupling system for the bi-directional transmission of digital data |
| US4652877A (en) * | 1983-07-01 | 1987-03-24 | Rockwell International Corporation | Meter data gathering and transmission system |
| US4782341A (en) * | 1983-07-01 | 1988-11-01 | Rockwell International Corporation | Meter data gathering and transmission system |
| US4725839A (en) * | 1984-12-21 | 1988-02-16 | Ferranti Subsea Systems, Ltd. | Remote, inductively coupled, transducer interface |
| DE69127075T2 (en) * | 1990-02-21 | 1998-02-26 | Rosemount Inc | MULTIFUNCTIONAL INSULATION TRANSFORMER |
| US5450076A (en) * | 1991-01-25 | 1995-09-12 | Siemens Aktiengesellschaft | Method for reducing power loss in devices for contactless data and energy transmission, and apparatus for performing the method |
| EP0712105A3 (en) * | 1994-11-14 | 1997-02-05 | Clyde L Ruthroff | Electrical power and signal transmission system |
| DE19537223C1 (en) * | 1995-10-06 | 1997-02-13 | Grieshaber Vega Kg | Potential-free measuring arrangement |
| DE19640829A1 (en) * | 1996-10-02 | 1998-03-12 | Siemens Ag | Circuit arrangement with isolating amplifier and measurement sensor |
| DE10330193B3 (en) * | 2003-07-03 | 2005-04-21 | Krauss-Maffei Kunststofftechnik Gmbh | Injection molding machine with force sensor |
| FI20031875A0 (en) * | 2003-12-19 | 2003-12-19 | Valtion Teknillinen | Coil arrangement and method for vehicle tires |
| US20090115629A1 (en) * | 2007-11-06 | 2009-05-07 | Honeywell International Inc. | moving and stationary body system interfacing with a communications medium |
| US8410954B2 (en) * | 2007-11-06 | 2013-04-02 | Honeywell International Inc. | Moving and stationary body system using telemetry |
| US9086266B2 (en) * | 2008-10-21 | 2015-07-21 | General Electric Company | Wireless sensors, detection methods, and systems |
| US7975554B2 (en) * | 2008-10-21 | 2011-07-12 | General Electric Company | Wireless strain sensors, detection methods, and systems |
| GB2464698B (en) * | 2008-10-22 | 2011-12-28 | Brush Sem S R O | Electrical component fault detection |
Family Cites Families (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA878140A (en) * | 1969-05-12 | 1971-08-10 | S. Mackelvie John | Signal transmitting system for rotating apparatus |
| CH501898A (en) * | 1969-06-06 | 1971-01-15 | Patelhold Patentverwertung | Device for precision measurement of the slide movement in face plates rotating relative to a stationary part, in particular for machine tool controls |
| GB1318206A (en) * | 1970-03-23 | 1973-05-23 | Ass Eng Ltd | Inductive coupling |
| US3742473A (en) * | 1970-08-12 | 1973-06-26 | D Hadden | Pulse discriminator and telemetering systems using same |
| JPS5115459A (en) * | 1974-07-29 | 1976-02-06 | Kawasaki Heavy Ind Ltd | Kaitentaio kanshisuru hoho |
| DE2445337C2 (en) * | 1974-09-23 | 1986-05-15 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Circuit arrangement for the transmission of electrical measured value signals |
| SE396249B (en) * | 1976-01-13 | 1977-09-12 | Asea Ab | TOUCH-FREE SIGNAL TRANSMISSION |
| US4198621A (en) * | 1977-11-14 | 1980-04-15 | Crowcon (Instruments) Limited | Electrical remote sensing system |
| US4242665A (en) * | 1978-09-15 | 1980-12-30 | Action Instruments Company, Inc. | Two-wire transmitter |
| US4225851A (en) * | 1979-03-22 | 1980-09-30 | General Electric Company | Self-calibrated subcarrier telemetry system |
| US4242666A (en) * | 1979-05-23 | 1980-12-30 | General Electric Company | Range selectable contactless data acquisition system for rotating machinery |
| US4232922A (en) * | 1979-07-03 | 1980-11-11 | Teass Jr Horace A | Signal power coupling to rotary shaft |
-
1980
- 1980-04-04 US US06/137,422 patent/US4354190A/en not_active Expired - Lifetime
-
1981
- 1981-03-30 IT IT8120798A patent/IT8120798A0/en unknown
- 1981-04-01 KR KR1019810001098A patent/KR850000268B1/en active
- 1981-04-02 JP JP4849681A patent/JPS56166597A/en active Granted
- 1981-04-03 BR BR8102069A patent/BR8102069A/en unknown
- 1981-04-03 MX MX186716A patent/MX150880A/en unknown
- 1981-04-03 CA CA000374604A patent/CA1170746A/en not_active Expired
- 1981-04-03 ES ES501078A patent/ES8202144A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ES501078A0 (en) | 1982-01-16 |
| IT8120798A0 (en) | 1981-03-30 |
| BR8102069A (en) | 1981-10-06 |
| KR850000268B1 (en) | 1985-03-14 |
| JPS56166597A (en) | 1981-12-21 |
| KR830005613A (en) | 1983-08-20 |
| JPH023238B2 (en) | 1990-01-22 |
| ES8202144A1 (en) | 1982-01-16 |
| US4354190A (en) | 1982-10-12 |
| MX150880A (en) | 1984-08-08 |
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