US 3392723 A
Description (OCR text may contain errors)
c. E. CALVlN 3,392,723
ELECTRO-PNEUMATICALLY OPERATED BED OSCILLATOR July 16, 1968 Filed Aug. 9, 1965 5 Sheets-Sheet 1 Era].
POM/ 0M7 INVENTOR.
7 Wag July 16, 1968 c. E. CALVIN ,7
ELECTED-PNEUMATICALLY OPERATED BED OSCILLATOR Filed Aug. 9, 19,65
5 Sheets-Sheet 2 67742455 67 AzV/A/ g INVENTOR BY mwz c. E. CALVIN 3,392,723
ELECTRO-PNEUMATICALLY OPERATED BED OSCILLATOR July 16, 1968 5 Sheets-Sheet 5 Filed Aug. 9, 1965 July 16, 1968 c. E. CALVIN ELECTRO-PNEUMATICALLY OPERATED BED OSCILLATOR Filed Aug. 9, 1965 5 Sheets-Sheet 4 Q J I 70 M/V/V INVENTOR.
c. E. CALVIN 3,392,723
ELECTRO-PNEUMATICALLY OPERATED BED OSCILLATOR July 16, 1968 W N\ @m Filed Aug. 9, 1965 United States Patent 3,392,723 ELECTRO-PNEUMATICALLY OPERATED BED OSCILLATOR Charles E. Calvin, Thousand Oaks, Calif., assignor to Richfieltl Oil Corporation, Los Angeles, Calif., a corporation of Delaware Filed Aug. 9, 1965, Ser. No. 478,297 6 Claims. (Cl. 128-24) ABSTRACT OF THE DISCLOSURE An oscillatory bed and device for oscillating a bed which comprises a stationary support, a movable bed sup port, the movable bed support being oscillated by an inflatable air bag motor, a pump for inflating the bag motor, a valve system for permitting the inflation and the deflation of the bag motor, and an electronic circuit which includes a Wheatstone bridge circuit, timer switch means for selectively periodically electrically unbalancing the Wheatstone bridge, and circuit follower means for monitoring the position of the movable bed support and controlling the valves to move the bed support to rebalance the Wheatstone bridge are disclosed.
The present invention relates to therapeutic apparatus and, more particularly, to apparatus for tilting or oscillating a bed in order to therapeutically benefit the occupant thereof. Medical science has recognized the value of oscillatory therapy by which the body is slowly tilted back and forth for the purpose of aiding such conditions as arterial diseases of the lower extremities, shock, respiratory disturbances involving paralysis of resipration, phlebitis, stroke, etc. It is desirable to have the bed oscillator and bed support structure designed so that the feet are initially positioned lower than the heart and then moved upward by the oscillator to a position where the feet are above the heart. Since the drainage of blood into the feet and legs may be a slower process than the return of blood to the heart, the bed oscillator timing device may advantageously program a delay at the feets bottom-most position. Automatic operation is the only practical manner of bed oscillation. The automatic operating controls should be variable so that the bed travel, speed, and cycle can be varied. It is also desirable that the bed controls be adaptable for manual setting.
In the prior art several devices have been designed for bed oscillating purposes, however, they have been generally unsatisfactory because of the complexity of the apparatus, the vibratory and noise disturbances to the bed occupant, the space required to house the unit adjacent the bed, and the fact that suitable automatic timing apparatus had not been provided.
Accordingly, it is an object of my present invention to provide an improved automatically controlled bed oscillating apparatus.
It is also an object of my present invention to provide an automatically controlled pneumatic bed oscillating apparatus for cyclically raising and lowering at least one end of a bed.
It is also an object of the present invention to provide an automatic air bag motor control system for cyclically raising and lowering a bed.
It is also an object of the present invention to provide a safety lockout mechanism for a bed oscillator which returns the bed to its initial position in the event of a malfunction.
It is also an object of the present invention to provide a means for counterbalancing a load placed on one side of the bed to permit the bed to maintain a level position.
It is a further object of my present invention to provide a novel bed position indicating means for a bed oscillator.
Other objects and a more complete understanding of my present invention will become apparent from the following specification and the appended claims when taken in conjunction with the drawings, wherein:
FIG. 1 shows an isometric view of the bed oscillating apparatus showing the control box and the air pump unit;
FIG. 2 is a side elevation of the bed oscillating mechanism showing the relative position of the air bag motor;
FIG. 3 is a side elevation, partially in section, showing the apparatus of FIG. 2 with the air bag inflated and the top bed panel in its up position;
FIG. 4 is an end view taken on line 4-4 of FIG. 3 showing the scissor-type torsion bar arrangement;
FIG. 5 is a view, partially in section, taken on line 55 of FIG. 2 showing the connection between the lower bed panel, the torsion bar, and the scissor support arm;
FIG. 6 is a view, partially in section, taken on line 6-6 of FIG. 2 showing the control apparatus positioned between the bed panels of the bed oscillating apparatus;
FIG. 7 is a sectional view taken on line 7-7 of FIG. 6 showing the return spring which keeps the actuating cable taut;
FIG. 8 is a view, partially in section, taken on line 88 of FIG. 6 showing the actuating cable;
FIG. 9 is a schematic view of the air bag motor showing air flow during upward movement of the bed;
FIG. 10 is a schematic view of the air bag motor showing the air flow while the bed is static;
FIG. 11 is a schematic view of the air bag motor showing the air flow while the bed is being lowered;
FIG. 12 is a circuit diagram of the automatic control mechanism for the bed oscillator.
Referring now to the drawings generally, the embodiment of my bed oscillator invention shown in FIG. 1 in cludes a pair of panels 20 and 22 which are pivoted at one end with an inflatable air bag 26 positioned between the panels to alternately lift and lower the top panel 20 on which the bed may be positioned as air is injected into and exhausted from the air bag with a motor driven pump. The flow of air through the pump is controlled by solenoid valves contained in the pump unit 28. The solenoid valves are controlled through control relays by a polarity sensing relay which is actuated by the current flowing across a Wheatstone bridge circuit when an unbalance condition exists in the bridge circuit. The bridge circuit is arranged as a rebalancing follow-up between a cycle timing potentiometer and a bed position indicating potentiometer. The bridge circuit includes a motor driven clock potentiometer 45 on one side and a bed potentiometer 48 (which follows the bed position by virtue of a cable and return spring arrangement) on the other side. Driving the clock potentiometer creates an unbalanced condition in the Wheatstone bridge causing the polarity sensing relay 46 to operate the air solenoid valves 47 and 49 to move the bed and hence the bed potentiometer into a position which will balance the Wheatstone bridge. The clock potentiometer therefore paces the bed operation by continuously and cyclically varying from 0 to the highest preset position of the bed.
Referring more particularly to the drawings, FIG. 1 shows a bed lifting mechanism 30 on which a bed can be laid. In the apparatus shown, the two bed panels 20 and 22 are pivoted at the head end of the bed oscillator about pivots 24. The panels are arranged so that in the initial position with the bag deflated, the head end of the bed, as best shown in FIG. 2, is slightly higher than the foot end of the bed. This arrangement may be accomplished by inserting tapered support blocks 32 under the lower panel. When the top panel is raised about the pivot 24 by the air bag motor, that is, by inflating the air bag 26, the foot end of the bed oscillator is higher than the head end, as shown in FIG. 3. The upward travel of the foot end of the bed is limited by scissor connectors 34 which are connected to channels 36 under the top bed panel 20 and at its lower end to opposite ends of torsion bar 38 which is affixed to the lower panel. The torsion bar-scissor connector arrangement provides lateral stability since a force exerted on one side of the bed, such as would be exerted by a person sitting on one side of the bed, is counterbalanced through the torsion bar. The connection between the torsion bar and the scissor connector is best shown in FIG. 5.
A limit block 40 is provided to limit the downward movement of the top panel 20 and a static line 42 limits the upward movement of the foot end of this panel.
While my bed oscillator has been illustrated with respect to one embodiment in which a device is shown for lifting the mattress or box springs with a pair of pivoted panels, it is within the scope of my present invention to provide an oscillator mechanism utilizing an air bag motor which lifts the bedposts or other members of the bed, as shown, for example, in U.S. Patent No. 2,566,239 to Mininberg or U.S. Patent No. 2,700,382 to Brand, or as shown in the copending application of Wittke, Ser. No. 428,468 filed Jan. 27, 1965.
Air is supplied to and exhausted from the air bag by a motor driven pump '68 (FIGS. 9-11) contained in the pump unit 28. The flow of air through the pump is controlled by air solenoid valves (FIGS. 9l1) which are also housed in the pump unit 28. The solenoid valves may be actuated by a polarity sensing micropositioner relay 46 which is energized by the flow of current across the bridge circuit caused by unbalance in the circuit when the clock motor drives the clock otentiometer 45 which is contained in the control unit 29. Power for the s cillator unit is supplied through power line 100 (FIG. 12) and the voltage may be reduced in transformer 102 for safety purposes. The alternating current from the power source is rectified by rectifier 104 and supplied to the operating unit as direct current.
Bed potentiometer 48 is positioned between the panels 20 and 22 and coupled to shaft 50 around which actuating cable 52 is wound on spool 54. The shaft is rotatably mounted on the bottom bed panel 22 and one end of the cable is afiixed to the top bed panel so that when the actuating cable is kept taut, the potentiometer 48 indicates the height of the bed lifting panel 20. When the clock motor drives the clock potentiometer according to a predetermined time schedule, air is supplied to or exhausted from the air bag to move the bed up or down, and, hence move the bed potentiometer through cable 52 and shaft 50 until the bed potentiometer gets on schedule at which time there will be a balance in the bridge circuit between the bed potentiometer and the clock potentiometer, At this point the bed will not move until the clock motor again moves the clock potentiometer into an unbalanced bridge condition. Thus, the bridge circuit provides means for selectively and controllably operating the solenoid valves and controlling the timing of operation of the valves.
The actuating cable 52 is kept taut by a return spring 56 which is anchored at one end 58 to a support block and at the inner helical end to shaft 50. The relative height of the bed is indicated continuously at the control panel 31 on a position indicator 60 by a position indicator transmitter 62 which is coupled to the shaft 50.
The air bag motor is operated to lift the bed in accordance with the air flow diagram shown in FIG. 9 with pressurized air received from the discharge side of pump 68 through conduit pipe 74. When the bed is being lifted, air is taken in through filter 64 through the solenoid valve 66 to the inlet side of the motor driven pump 68 where the air is pressurized and pumped through a regulator 70,
an up solenoid valve 72, pipe 74, preset restrictor 76, and into the air bag 26.
When the bed is held in a static position, the air flow is as shown in FIG. 10. Valves 66 and 72 are closed to the passage of air from the bag so that air is held in the bag 26. Air drawn in through the filter 64 is pumped out the discharge pipe of the solenoid valve 72. The solenoid valves 66 and 72 are three-way valves. The safety solenoid valve 84 is a shutoff type valve.
In order to lower the bed as shown schematically in FIG. 11, air is withdrawn from the bag through restrictor 76 and pumped to exhaust through the exhaust pipe 80 of the solenoid valve 72. The restrictor valve 76 in the air conduit from the air bag 26 reduces the sensitivity of movement of the top bed panel.
In the event of a malfunction such as bed overtravel, the safety switch 82 (FIG. 12) which is positioned on the head of the bed opens the safety solenoid valve 84 to allow discharge of air from the bag, as shown in phantom line in FIG. 11.
As can be seen from the circuit diagram in FIG. 12, when the lockout safety switch 82 is closed, the safety lockout relay 86 turns oil the clock motor 88 and all power to the solenoids and the pump motor 69 and opens solenoid valve 84 which lets the air out of the bag by static weight on the bed. In other words, the overtravel safety device shuts off all of the operating mechanism except the safety solenoid which allows the bed to return slowly to normal position. The bed oscillating mechanism stays in lockout position until the master switch 90 is turned off and back on again. When a lockout occurs, a warning light is lit on the panel to indicate a malfunction. The safety solenoid valve 84 which releases air from the bag is an entirely separate solenoid valve from those used in the normal bed oscillating operation and is actuated only when the bed travels above the normal operational travel height.
The height to which the bed is oscillated can be changed by setting the multi-position selector switch 92 on the control panel 31 to one of the settings numbered 4 through 10 which selectably inserts resistances 93 in series with the clock potentiometer to determine the height of bed travel. Upon reaching the selected height, the bed will then be operated automatically since the bed will travel up or down until the bed potentiometer 48 is balanced in the bridge circuit with the clock potentiometer 45.
The bed can be run up or down or stopped by manually controlling the up or down position of switch 92. That is, when the operator desires to raise the bed, the switch is turned to the up position and the bed is raised until the switch is changed to the stop position or until the top oscillating height is reached at which time it stops. This switch also has positions or settings for down and stop. The switch shown at 92 is operated with a single control, although three switches are used to obtain the scope of operation desired. The three switches may be stacked wafer switches with the one control. In the event that the bed has been operated by manually changing the selector switch and then is set to a particular height setting, this setting causes the bed to operate automatically to a movement of this preselected height, and the bed will travel to the nearest in-balance relationship. For example, if the bed has been run up or down by selecting the up, down, or stop position on the selector switch control and is then put on automatic operation by setting the selector control for a 7 stroke, the bed would go to the nearest position in relationship to the clock schedule and then proceed on the automatic timing schedule, as previously mentioned.
The clock potentiometer rotates continually from 0 to 500 to 0 ohms and may be operated with a rest period at the bottom. The bed potentiometer is basically a reciprocal type potentiometer, for example, 500 ohms full travel to permit the use of a clock potentiometer of 1,000 ohms having a center tap at 500 ohms. The clock potentiometer 45 moves on a time schedule to vary the resistance of one leg of the Wheatstone bridge between, for example, 0 and 500 ohms and then back to 0 ohms. The oscillation height is controlled by the setting on the multi-position selector switch 92 which puts one of several resistances 93 in series with the clock potentiometer. It the bed potentiometer is at, for example, 25 ohms, and the clock potentiometer is at, for example, 200 ohms, there would be an unbalance in the Wheatstone bridge and a current would flow across the bridge to actuate the polarity sensing relays which in turn control the air solenoid valves to supply air to or release air from the air bag 26 until the bed potentiometer gets in time with the clock potentiometer and then the bridge is in balance and no air flows in either direction. If the bed potentiometer gets either ahead or behind, then an out-of-balance condition exists which, as previously mentioned, actuates the polarity sensing relay which operates the coil in the relay to open or close the appropriate air solenoid.
The controlling unit for operating the solenoid coils is a polarity sensing relay unit which may include either a mechanical switching device such as a micropositioner as shown in FIG. 12 or an electronic or solid state (transistor) switching device to actuate the control relays in the solenoid valves 47 and 49.
Although my present invention has been described herein with a certain degree of particularity, the scope of the invention is not limited to the details set forth, but is the full breadth of the appended claims.
1. An electrically controlled pneumatically powered apparatus for oscillating a bed, comprising:
a stationary bed support,
a movable bed support,
an air bag motor for moving said movable bed support to thereby oscillate said bed at least at one end of said bed about a horizontal plane,
a source of air under pressure connected through conduit means to said air bag motor,
electrically controlled air valves in said conduit means for controlling the application of air pressure to and exhaust from the air bag motor, and
an electrical circuit including timer controlled circuit unbalancing means and follower circuit means for 45 selectively and controllably operating said valves and controlling the timing of operation of said valves.
2. A bed oscillating apparatus as defined in claim 1 including a torsion bar and means connected thereto interconnecting both sides of the bed supports.
3. A bed oscillating apparatus as defined in claim 1 wherein the electrical circuit includes a safety lockout relay operated by a switch upon overtravel of the bed.
4. A bed oscillating apparatus as defined in claim 1 wherein the electrical circuit includes a re-balancing follow-up bridge circuit electrically connected to a polarity sensing relay, which in turn controls the electrically controlled air valves of the air bag motor, a clock motor driven potentiometer for cyclically unbalancing one side of the bridge circuit, and a bed position following potentiometer variable with the bed position connected in other side of the bridge circuit, the arrangement being such that cyclic movement of the clock potentiometer unbalances the bridge, operating the polarity sensing re lay, controlling the air valves, operating the air bag motor to move the bed support, thus moving the bed potentiometer in a direction to re-balance the bridge and follow the cyclically moving clock potentiometer.
5. A bed oscillating apparatus as defined in claim 4 wherein the bed position following potentiometer is connected to the bed by a cable, which in turn is kept taut by a return spring.
6. A bed oscillating apparatus as defined in claim 4 further including a plurality of selectable resistances insertable in series with the clock potentiometer to determine the height of bed oscillation.
References Cited UNITED STATES PATENTS 1,772,310 8/1930 Hart 12833 XR 2,437,006 3/1948 Simpson 128-33 2,678,452 5/1954 Beern et a1. 128-33 XR 2,819,712 1/1958 Morrison 12833 3,071,130 1/1963 Hoyer et a1. 3,247,528 4/1966 Swenson et al. 128-33 XR FOREIGN PATENTS 581,796 8/1933 Germany.
L. W. TRAPP, Primary Examiner.