US2291654A

US2291654A - Fuel system and pressure switch therefor

Info

Publication number: US2291654A
Application number: US353539A
Authority: US
Inventors: Samiran David
Original assignee: Individual
Current assignee: Individual
Priority date: 1939-03-13
Filing date: 1940-08-21
Publication date: 1942-08-04
Anticipated expiration: 1959-08-04

Description

Aug. 4, 1942. D. SAMIRAN 2,291,654

FUEL SYSTEM AND PRESSURE SWITCH THEREFOR Filed Aug. 21, 1940 2 Sheets-Sheet l z- 4, 1942- D. SAMIRAN 2,291,654

FUEL SYSTEM AND PRESSURE SWITCH THEREFOR Filed Aug. 21, 1940 2 Sheets-Sheet 2 Patented Aug. 4, 1942 OFFICE FUEL SYSTEM AND PRESSURE SWITCH THEREFOR David Samiran, Fairfield, Ohio Original application March 13, 1939, Serial No. 261,542. Divided and this application August 21, 1940, Serial No. 353,539

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 21 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The present invention relates in general to fuel systems provided with a plurality of separate fuel sources and more particularly to a fuel system in which the contents of fuel containers representative of such fuel sources are automatically connected in predetermined order to a source of fuel consumption, the present application being a division of my co-pending application, Serial No. 261,542 filed March 13, 1939.

It is an object of this invention to make use of fuel pressure drop in a'fuel pressure switch of novel construction induced by successive fuel exhaustions to effect automatic connection of the source of fuel consumption with a succeeding full fuel container, the action of the fuel pressure switch being modified by changes in pressure of a supercharger when the present invention is applied to an airplane engine or the like employing a supercharger in connection with the fuel injector or carburetor of the engine.

A further object is to provide a fuel pressure switch of such construction and operation that it may be interconnected with the fuel source selector means to accomplish a resetting of the fuel pressure switch by the selector means when a, new fuel source has been connected with the source of fuel consumption by the selector means.

Still a further object is to provide a fuel pressure switch wherein the building-up of fuel pressure carries the switch (in an open circuit condition) from one position to another; the fuel selector means then cooperates with the switch to open the circuit thereof when the new source of fuel has been completely connected with the source of fuel consumption and subsequently when the new source of fuel become exhausted and the fuel pressure accordingly recedes, the fuel pressure switch thereupon returns to position to effect closure of the circuit, the circuit controlled by the switch being in turn connected with the fuel source selector means to shift it to a new position for receiving fuel from another full container.

The foregoing mentioned objects and advantage of my invention will become apparent from the following description taken in connection with the accompanying drawings, it being clearly understood that the same are by way of illustration only and are not to be taken as in any way limiting the spirit or scope of my invention. On

the contrary the spirit or scope of my invention is to be limited only by the prior art and by the terms of the appended claims.

Referring now to the drawings wherein like reference characters designate similar parts throughout the several views:

Figure 1 is a diagrammatic representation of a fuel system embodyin my invention and including my novel fuel pressure switch.

Figure 2 is an enlarged sectional view through the pressure switch itself showing the parts in one position and cooperating with a cam of the source selector means; and

Figure 3 is a side elevation of the lower portion of Figure 2 showing the switch in further positions which it assumes during operation.

In the present invention I seek to accomplish two objectives.

First, I am concerned with providing means whereby a source of fuel consumption, such as an internal combustion engine fuel injector, or carburetor, may be readily interconnected with any one of a plurality of fuel containers through simple manual turning of the control handle of a selector valve.

Second, I seek to provide means for automatically turning the aforesaid selector valve from a container from which all fuel has just been exhausted to the next fuel container in selector valve order from which fuel has not yet been exhausted. To accomplish the second objective I provide a selector valve operating means including a fuel pressure switch which is primarily responsive in two different positions to presence and substantial reduction of the pressure of the fuel being supplied to the fuel injector or carburetor, the switch in turn electrically controlling the operation of the fuel selector means which itself is of an electrically operated type.

Merely by way of illustration-I provide three fuel containers I, 2 and 3. Obviously a greater or less number of containers may be provided without in any way departing from the spirit of my invention. The fuel containers I, 2 and 3 are separately connected to a like number of inlets provided in a selector valve I by means of copper tubes or the like 5, 6 and I respectively. A single outlet 8 from the selector valve 4 is connected by a conduit 9 to a fuel strainer ID. The outlet of the fuel strainer is connected by conduits I I, I2 and I3 to an engine driven fuel pump I4 and a manually operated wobble pump I5. The shaft of the pump I4 is indicated at I6 and of course is appropriately and operatively connected with the engine (not shown).

The outlet of the fuel pump I4 is connected with a switch pressure regulator H, the construction of which is shown in my co-pending application hereinbefore referred to. Fuel from the'pump l4 passes through the regulator I1 and then through pipes l3 and I! to an air-vapor eliminator 20 also shown in my co-pending application. The air vapor eliminator 20 and the switch pressure regulator l1 are described in detail in my additional co-pending application Serial No. 335,646 filed May 16, 1940, and Patent No. 2,275,472, dated March 10, 1942, respectively. When the wobble pump 15 is operated, fuel passes through a pipe 2| and the pipe I! to the airvapor eliminator 23. The air and vapor from the eliminator 20 may be returned through a pipe 22 to one of the fuel containers such as 3 and the fuel under pressure from the air-vapor eliminator is conducted through a pipe 23 to a fuel injector or carburetor (a fuel injector bein indicated at 24).

The switch pressure regulator l1 supplies fuel under pressure through a copper tube or the like 25 to the fuel pressure switch of my present invention indicated generally at S. The construction of the regulator I1 is such that the fuel pressure in the tube 25 never exceeds a predetermined amount somewhat lower than the normal pressure of fuel supplied by the pump l4 to the air-vapor eliminator 20 as determined by the setting of the pressure regulator. The injector 24 includes a bypass valve 26 set at a predetermined pressure so that fuel in excess of the requirements of the injector 24 are returned through a pipe 21 to the intake side of the pump I 4.

Returning now to the specific structure of the selector valve 4, a suitable housing is provided with the three 90 spaced inlets a, 6a and 1a receiving the discharge ends of the

pipes

5, 6 and 1 respectively. Within the casing of the selector valve, a truncated conical cavity is provided which receives a cork faced tapered valve plug 23. The cork facing is indicated at 29. The valve plug 28 is provided with a short driving shaft 30 protruding through a boss 3| of the valve casing. The valve plug is provided with an L-shaped passageway 32 having a short end projecting through the valve plug face of smaller diameter and coaxially located with respect to the shaft 30 and the outlet 8. The L-shaped passageway 32 has a long end disposed normal to the axis of the shaft 30, such that it may be successively registered with the intake bosses 5a, 5a and 1a. a

In order that the selector valve 4 may be remotely controlled from a control panel 33, I have provided an extension shaft 34 coupled to the valve operating shaft 30 as by a coupling sleeve 35 and suitable drive pins. A control handle 36 is fixed to the opposite end of the extension shaft 34 and is provided with a pointer 31 to cooperate with indicia as "No. 1, No. 2, No. 3 and ofi indicating that the selector valve connects the fuel pumping system with any tank I, 2 or 3 or with none of them.

For effecting automatic rotation of the extension shaft 34 and thereby changing the position of the selector valve 4 without attention by the operator, I provide the following described solenoid operated ratchet mechanism. A ratchet wheel 33 is secured to the shaft 34 and is adapted to be rotated in one direction by a pawl 39. The pawl 33 is pivoted to a core operated plunger 40 which in turn is connected with a core 4| within a solenoid coil 42'. Whenever the solenoid coil 42 is energized, the plunger 40 and the pawl 33 are propelled in a right-hand direction for engaging a tooth of the ratchet wheel for imparting clockwise rotation thereto through a distance of one tooth. The core 41 is spring returned as by a spring 43 so that when the coil is de-energized, the pawl 39 will be pulled backwardly and will drop behind the next tooth of the ratchet wheel.

From the construction of the parts just described, it will be obvious that energization of the solenoid will cause a single tooth advancement of the ratchet wheel. It is desirable, however, that the ratchet wheel rotate in order to shift the L-shape passageway 32 from one inlet of the selector valve'4 to the next one as for instance from the inlet 5a to the inlet 6a. To accomplish this result, I connect a toggle switch 44 in series with the solenoid coil 42 and operate the toggle switch by locating its operating lever 45 between a pair of projections 44 on the plunger 40. Accordingly, when the solenoid is energized, it will be advance the ratchet wheel one tooth and in doing so will swing the lever 45 of the toggle switch 44 to 011" position so that the spring 43 will return the pawl 33. The return of the pawl effects return of the toggle switch 44 to "on position so that there will be another energization of the solenoid coil and the cycle repeated so long as current is supplied through the switch 44 to the solenoid. The current, however, is automatically and usually shut off on the quarter turn as will hereinafter appear.

Also affixed to the extension shaft 34 is a control disc 41. The disc 41 has a plurality of cam lobes 41a, 41b and 41c corresponding respectively to the inlets 5d, 6a and 1a of the selector valve 4. The control disc 41 is adapted to cooperate with the switch S as will be described after the construction of the switch itself has been described.

The fuel pressure responsive switch 8 is composed of many parts variously disposed in and about a cylindrical housing 43. The housing 48 has a top wall 49 and a bottom plate 50. The plate 50 is mounted onthe plate 44 as by cap screws or the like 5| with a gasket 52 interposed between the housing and the plate 50. A washerlike element 53 is interposed between the gaskets and the plate 50 and has one end of the bellows 54 secured to its inner diameter. The other end of the bellows is secured to the outer diameter of a disc 55 to which an operating stem 56 is secured.

The stem 56 extends slidably through a bearing sleeve 51 in the plate 53. The pressure line 25 shown diagrammatically in Figure 1 communicates with a boss 54, which in turn is connected by a passageway 33 to a cavity 63 within the ,housing 48 surrounding the bellows 54. The interior of the bellows constitutes a cavity 6| which is vented at 62 to atmosphere to avoid restricting the response of the bellows 54 to fuel under pressure from the conduit 25.

Above the partition 43, a cylindrical member 63 is secured to the cylindrical housing 43 by cap screws 64 or the like with a diaphragm washer 65 interposed between the member 53 and a gasket 66. The gasket 63 seals the diaphragm washer 65 with respect to the partition 49 thereby providing a sealed cavity 41 within a bellows 63. The bellows 44 has one end secured to the inner diameter of the washer 55.

The fuel system shown in Figure 1 includes a 82 of an adjusting nut 83.

cooperate with the roller I 08 for holding the roller in either the position of Figure 2 or the full line position of Figure 3' after the switch arm I88 has been swung to either of said positions.

The contactor plates I89 and II are assembled in position on the carriage bar 95 as by screws II2 with blocks of insulation H3 and H4 the exhaust. gases from the engine,- some of.

which may be permitted to escape through a bypass I5if there are exhaust gases in excess ofdownwardly extending sleeve 80; .The sleeve 80 is provided witha pair of-diametrica'lly opposite slots SI which slidably receive apair of fingers A stop-ring 84 for the fingers 82 is provided in agroove around the sleeve 80 adjacent its lower end. The adjusting nut 83 is threaded on the lower end of an and the stem 85v together with the

parts

19 and 81 are all secured together by a lock nut 88. The stem 85 is provided with a flange 89 to engage against the plate I9 for the purpose of providing a. rigid assembly. The adjusting nut 83 is provided for changing the tension of a spring 90 interposed between the adjusting nut 83 and a seat 9I in the partition 49.

The carriage bar 81 is connected by tie-rods 92, lock washers 93 and lock nuts 94 to a second carriage bar 95. The tie-rods 92 are slida-ble in holes 98 drilled through the tubular housing 48 and through holes 91 drilled through the member 63 and arranged in alignment with the holes 98. To conserve space on the drawings, the central portions of the tie-rods 92 have been broken away in Figure 2 and the

bosses

58 and 11 shown, whereas, actually the bosses are not in the plane of the tie-rods, but are rotated a substantial number of degrees around the housing 48 to avoid interference with the tie-rods.

The stem 58 of the bellows 54 is provided with a shoulder 98 adapted to engage a hub 99 of the carriage bar 95 to propel it downwardly against the bias of the spring 90. The lower cover plate is tapped as indicated at I00 to receive a projecting stud IOI. A check nut I02 retains the studin any desired adjusted position. Prior to installation of the stud NH and the nut I02, a sheet of insulation I03 is fastened against the cover plate 50 and the vent 82 extends through both the cover plate and the sheet of insulation.

The lower carriage bar 95 is provided with a pair of perforated ears I04 carrying a pivot pin I05. A switch arm I08 is pivoted thereto and has a slidably mounted plunger I01 formed of suitable insulating material. The plunger I01 carries a metallic roller I08 adapted at times to bridge contact plates I09 and H0 as shown in Figure 2. The plunger I 01 and the roller I08 are urged toward the contact plates by a spring III, the plunger I01 being guided against rotation by slots and pin connection I08a--I06b. The contact plate I09 has a knife or V-edge to to properly insulate them from each other and from the other metallic parts of the structure shown in Figure 2. The switch arm I08 has a cam lobe us to cooperate with any one of the cam lobes 41a, 41b, or 41c of the control disc 41, as will hereinafter appear.

The tension of the spring 90 may be adjusted by first loosening the lock nut 88 and then turning the adjusting stem by means of a screwdriver in a slot II8 ofithe stem. Turning of the-stem causes the spring adjusting nut 83 to be lowered or raised to effect increase or decrease of the spring tension as-desired. Thereafter, the nut 88 may be retightened to retain the adjustment and to compress the gasket 86. This adjustment assures awide range of varying spring compressions tending to maintain the spring carriage 8192--95 in araised-position. The projecting stud IOI may be' adjusted to different positions as desired by inserting a pin through an opening Ill thereof and turning the stud after the check nut I02 has been loosened. It is preferred to adjust the stud IOI to aposition where the further'upward displacement of the carriage 8I'-92-95 by the spring 90, after the roller I08 is brought into bridging contact with contacts I09 and H0, will cause the arm I06 to again contact the stud I M to thereby maintain the roller I08 in engagement with the contact IIO with a substantial force.

The upper portion of the fuel pressure switch S is provided with a dust cover Illa, which is vented as at II8 to atmosphere to prevent compression ofair within the dust cover surrounding the bellows .68 and interfering with its action. In the event that the switch S is used with an unsupercharged engine, the pipe connection I6 with the boss 11 is dispensed with and the .boss vented to atmosphere, thereby venting the interior of the bellows 88 to atmosphere.

1 Referring again to the diagrammatic'showing in Figure 1, the electrical control circuit for the selector -valve operating ratchet wheel 38 controlled by the switch S includes a source of electric current such as a battery II9. An ignition switch for the engine is indicated at I20. The switch I20 is connected by a wire I2I to the negative side of the battery H9 and a wire I22 extends to the ignition system of the engine in the usual manner. A terminal panel I23 is provided on which is mounted a negative terminal I24. a positive terminal I25, and a control terminal I26. The negative terminal I 24 is connected with the ignition switch I20 by a wire I21 to that current is supplied to the terminal panel I23 only when the ignition system is in operation. By a wiring arrangement of this character, the automatic operating mechanism for the selector valve is rendered inoperative any time the engine is not in operation.

The positive terminal of the battery I I9 is connected by a wire I28 with the positive terminal I25 of the terminal panel I23. Current is supplied from the terminal I25 through wires I29 and I30 to the switch S and to an indicator light I3i respectively. The wire I29 is connected with the contact plate I09 of the switch S while the contact plate IIO thereof is connected by a wire I 32 with the control terminal I26. It is accordingly obvious that whenever the roller I09 bridges the contacts I09 and I I current will be supplied from the positive side of the battery II9 through I28, I25, I29, I09, I08, H0 and I32 to the terminal I26. From the terminal I26 the current divides so that part goes through a wire I33 to a test switch I34 of the indicator light I3I and to the electric bulb I35 of the indicator light. The current to the bulb then returns through a wire I36 and through I24, I21, I20 and III to the negative side of the battery. Thus closure of the switch S automatically energizes the indicator I35.

Any time the operator desires to test the indicator light, a push rod I31 may be pushed inwardly for closing the test switch I34, which is connected directly across the positive and negative terminals I25 and I24 of the panel I23 with the bulb I35 in series therewith.

Closure of the switch S also causes the rest of the current from the terminal I26 to flow through a wire I38 to a relay coil I39, returning by way of a wire I40 to the negative terminal I34. Energization of the relay coil I39 causes it to attract an armature I of the relay (indicated generally at R) thus closing the contacts I42 of the relay. Current from the positive terminal I24 is supplied through a wire I43 to the contacts 2 from which it flows through a wire I44 to a selector switch I45 mounted on the panel 33. The current then flows through a wire I46 to the toggle switch 44 and a wire I41 to the solenoid coil 42, returning by way of a wire I48 to the negative terminal I24 on the terminal panel I23.

From the explanation of the parts just referred to, it is obvious that closure of the switch S, in addition to operating the indicator light I3I operates the solenoid 42 through the medium of the relay R whereupon the solenoid in conjunction with the toggle switch 44 produces step by step rotation of the ratchet wheel 38 as already described. Rotation of the ratchet wheel also rotates the control disc 41 with its cams 41a, 41b and 410, which so cooperate with the switch S that they open the switch at the completion of a quarter turn of the selector valve 4.

In order to understand just how the control disc cooperates with the switch S I will now refer to Figure 2. Due to a drop in pressure in the conduit 25 and a consequent drop in pressure in the cavity 60 surrounding the bellows 54, the bellows in Figure 2 has been expanded by the spring 90. The drop in pressure in the conduit 25 is a result of the fuel tank I becoming emptied and thereby the pump I 4 running out of fuel. The

tanks

2 and 3, however, are full as indicated by the liquid level lines 2a and 3a respectively.

In Figure 2 the switch carriage, consisting of the carriage bars 81 and 95 and the tie-rods 92, is in raised position which causes the projecting stud IN to be engaged by the switch arm I06 and the switch arm therefore to be swung downwardly with relation to the carriage bar 95, Accordingly, the roller I08 has passed across the knife edge of the contact I09 and bridged the contacts I09 and H0. The circuit is now closed through the switch S thereby effecting energization ofJ-the indicator bulb I35 and the relay R. The solenoid 42', under control of the relay, is accordingly energized and the rotation of the ratchet wheel 38 is just commencing.

While the cam lobe 41a is rotating a quarter turn clockwise, the cam 41b is coming up to position of alignment with the switch arm cam lobe II as shown by dotted lines in Figure 3. When the L-shaped passageway 01' the selector valve 4 begins to register with the inlet 6a of the selector valve, the pump I4 will start to pump fuel to the fuel injector 24, Accordingly, the pressure will be built up in the switch pressure regulator I1 and in the conduit 25 leading to the cavity 60 of the switch S.

This will result in the pressure of the fuel forcing the bellows 54 to collapse against the action of the spring 90, thereby moving'the switch carriage from the position of Figure 2 to the position of Figure 3 with the switch arm I06 in dotted position. Such movement downwardly of the carriage will occur prior to registry of the cam lobe 41b with the cam lobe I I5. When the quarter turn is completed, the cam lobe 41b will engage the cam lobe H5 and swing the switch arm: I06 upwardly to the full line position thus breaking the circuit at the switch S and thereby deenergizing the solenoid 42 and stopping the ratchet wheel at the proper position with the L-shape passageway of the selector valve in exact registry with theinlet 6a.

If it so happens that the fuel tank 2 is empty, then, of course, the pressure will not be built up in the pipe 25 to move the switch carriage from the position in Figure 2 to the position of Figure 3 with the result that the switch S' will remain closed in the position of Figure 2 to permit the cam lobe 41b to pass without opening the switch. Subsequently the cam lobe 410 will open the switch when the L-shaped passageway is in registry with the intake 1a of the tank 3 providing there is fuel in the tank 3. Thus I am assured of automatic changing of the position of the selector valve from an empty tank to a tank having fuel in selector valve order.

Due to the ratchet and pawl mechanism 3839, the selector valve can be manually moved clockwise by the control lever 36 to connect with any desired tank. If at any time the operator wishes to render the automatic selector valve operating mechanism inoperative, he can do so by opening the selector switch I45. The spring 'of the switch S may be set at the desired value for proper closing of the switch S or downward shifting of the switch carriage as in Figure3 in accordance with the desired low and high fuel pressures effective in the cavity 60.

Where an aircraft in which my system is installed is equipped with an engine having a supercharger that controls the supply of air to the intake of the engine, the pressure required to deliver fuel to the injector remains substantially constant due to the action of the pressure relief valve 26 of the injector as the aircraft continues to gain altitude. Air pressure against the inside of the bellows 54 however steadily decreases. It naturally follows that the. aforesaid decrease in air pressure tends to collapse the bellows 54. Should only the spring 90 resist the aforesaid collapse of the bellows, premature downward movement of the switch carriage would result.

To prevent such premature movement, the cavity 61 within the upper bellows 68 is directly fiuid connected through the pipe 16 with the in duction system of the supercharged engine as by connection into the pressure supply pipe H of the supercharger 69. This effects complete compensation for the fuel pressure increase above mentioned. Such compensation is a result of the supercharger maintaining a substantially constant pressure on the air supplied to the engine. The purpose of a supercharger is to maintain such constant pressure (for instance, sea level pressure) regardless of the altitude to which the airplane ascends. Accordingly by making the connection at 16, the constant air pressure supplied by the supercharger will also maintain a substantially constant pressureinside the bellows 68. Outside of the bellows 68- ambient air pressure decreases as the altitude increases thereby tending to expand the bellows 68. This results in a tendency to produce upward movement of the switch carriage whereas the reduced ambient air pressure acting inside the bellows 54 as above pointed out tends to produce downward-movement thereof. Accordingly, constant fuel pressure within the chamber 60 surrounding the bellows 54 and constant supercharger pressure within the cavity 6'! inside the bellows 68 balance each other to prevent movement of the switch carriage as long as fuel is supplied to the fuel pump and the ambient air pressure tending to collapse the bellows 54 and expand the bellows 68 cause a further balance resulting in the desired compensation. The result is that the movement of the switch carriage is accurately in response to changes in the fuel pressure to give the desired operation to the switch which in order to operate the selector valve properly must respond to fuel failure as reflected in a drop of fuel pressure when the pump runs out of fuel.

Having described a fuel system in which my pressure responsive switch is used together with the operation thereof, it is believed obvious how the selector valve 4 is automatically changed from one position to another in response to the emptying of any of the fuel containers I, 2 or 3 under control of the switch S, the switch in turn being responsive to a predetermined drop in fuel pressure occasioned by emptying of a fuel container (and its response being modified by connection with a supercharger in the event that the engine is so equipped). The supercharger connection compensatesfor a gain in altitude of the aircraft in which the system is installed. ;Where there is no supercharger, then the interior cavity 61 of the bellows 68 is vented to atmosphere so that the bellows 68 is inefiective to modify the action of the bellows 54.

My invention has been described in the foregoing specification and illustrated in the drawings more or less precisely as to details. It is to be. understood, however, that changes may be made in the arrangement and proportions of parts and equivalents may be substituted without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A pressure responsive switch'for use in a fuel dispensing system including a selector valve, means for operating said switch in conjunction with said selector valve comprising a bellows with an externally projecting stem, 2. support piloting said projecting stem and substantially closing the open bellows end, and contactor means carried by said support and adapted to be closed by said projecting stem upon predetermined bellows expansion effecting movement of said support, said switch cooperating with said selector valve to be opened thereby only when said support is in a predetermined position.

2. A pressure responsive switch for use in a fuel dispensing system including a selector valve, means for operating said switch in conjunction with said selector valve comprising a bellows with an externally projecting stem, 3. support piloting said projecting stem and closing the bellows end,

a single fluid inlet-outlet connected with said bellows, and contactor means carried by said support, adapted to be closed by said projecting stein upon predetermined bellows expansion, and adapted to be opened by said selector valve assuming a selector position at a time when said support is in the position it assumes as a result of bellowscontraction.

3. A pressure responsive switch for use in a fuel dispensing system including a selector valve, means for operating said switch in conjunction with said selector valve comprising a bellows with an externally projecting stem, 9. support substantially closing the open end of said bellows, a spring positioned to resist collapse of said bellows, and contactor means carried by said support and so tensioned against said projecting stem as to close upon predetermined bellows expansion efifectmg movement of said support, said switch cooperating with said selector valve to be opened thereby only when said supportis in a predetermined position.

4. A pressure responsive switch for use in .a fuel dispensing system having a selector valve, said switch including a bellows with an externally projecting stem, a support providing the open bellows end with a single fluid inlet-outlet, a spring positioned to resist collapse of said bellows, and contactor means carried by said sup port and so tensioned against said projecting stem as to close upon predetermined bellows movement due to pressure drop and to be opened by said selector valve due to pressure rise and assumption of a selector position by said selector valve.

5. A pressure responsive switch for use in a fuel dispensing system having'a selector valve and an electrically operated means for changing the position thereof, said pressure responsive switch comprising a switch carriage, pressure responsive means connected with the fuel dispensing system so as to be responsive to pressure or absence of pressure therein and operabl to move said switch carriage in one direction upon decrease of pressure and in an opposite direction upon increase of pressure, a switch carried by said switch carriage and operable to closed position by engagement with a stationary stud when said switch carriage moves in said first mentioned direction as a result of fuel pressure decrease, said switch being operable to remain closed and to be moved bodily by said switch carriage when said carriage moves in said opposite direction as a result of fuel pressure increase, said switch being opened by said means for changing the position of said selector valve when said means assumes a new selector valve position and said switch being connected in circuit with said means to energize and deenergize the same in response to closing and opening of said switch.

6. A pressure responsive switch for use in a fuel dispensing system having a'selector valve and solenoid operated ratchet means for changing the position of said selector valve, said solenoid operated ratchet means including a toggle switch in circuit with the solenoid to cause repeated energizations and deenergizations of the solenoid during the time current is supplied thereto, said pressureresponsive switch comprising a switch carriage, pressure responsive means connected with the fuel dispensing system so as to be responsive to absence of pressure or presence of pressure therein and operable to move said switch carriage respectively in one direction or in the opposite direction as a result thereof, a

-switch carried by said switch carriage and opermoves in said first mentioned direction as a result of absence of fuel pressure; said switch being operable to remain closed and to be moved bodily by said switch carriage when it moves in said second mentioned direction as a result of presence of fuel pressure, said switch being opened by said solenoid ratchet operated means ofsaid selector valve when it assumes a new selector valve position and being connected in circuit with said solenoid and toggle switch.

7. A pressure responsive switch for use in a fuel supply system for an engine having a supercharger, said system having a selector valve and electrically operated means for changing the position of the selector valve, said switch comprising a switch carriage, pressure responsive means connected with the fuel supply system so asto be responsive to increase and decrease of pressure therein, said pressure responsive means being in communication with said supercharger for modification of the pressure responsive means in. response to variations in pressure produced by the supercharger, said pressure responsive means being operable to move said switch carriage in one direction upon decrease of fuel pressure and in an opposite direction upon increase of fuel pressure, a control-switch for said electrically operated means, carried by said switch carriage and operable to closed position when said switch carriage moves in said first mentioned direction, said control switch being operable to remain closed and to be moved bodily by said switch carriage when said carriage moves in said second mentioned direction, said control switch being opened by said electrically operated means when said means assumes a new selector valve position and said control switch effecting control of the circuit of said'electrically operated means.

8. A pressure responsive switch for use in a fuel dispensing system having a selector valve, a shaft for rotating the selector valve and electrically operated means for rotating said shaft, said pressure responsive switch comprising a switch carriage, pressure responsive means connected with the fuel dispensing system for response to absence or presence of pressure therein, said pressure responsive means being operable to move said switch carriage in one direction upon decrease of pressure and in the opposite direction upon increase of pressure, a switch carried by said switch carriage and operable to closed position when said switch carriage moves in said first mentioned direction, operable to remain closed and to be moved bodily by said switch carriage when it moves in said second mentioned direction, and a cam on said shaft for opening said switch when the cam assumes a position corresponding to a new selector valve position, said switch being connected in circuit with saidv electrically operated means to energize it by decrease of pressure in said pressure responsive means to a predetermined valve and deenergize it in response to said cam providing said pressure responsive means has in the meantime responded to an increase in pressure suflicient to move said switch carriage to a position where the closed switch thereof may be engaged by said cam.

' 9. 'A pressure responsive switch for use in a fuel dispensing system having a selector valve, a shaft for rotating the selector valve and electrically operated means for rotating said shaft, said switch comprising a switch carriage, pressure responsive means connected with the fuel dispensing system for response to changes of pressure therein, a control switch carried by said switch carriage andoperable to closed position' when said switch carriage moves in one direction, operable to remain closed and 'to be moved bodily by said switch carriage when it moves in the opposite directionand means on said shaft for opening said switch'when saidlast means assumes a position corresponding to a new selector valve position, said switch being connected in circuit with said electrically operated means in energize it by decrease of pressure in said pressure ,responsive means as a result of fuel failure and to deenergize it in response to said means on said shaft providing said pressure responsive means has in the meantime responded'to an increase in pressure sufilcient tomove said switch carriage to a position where the closed switch thereof may be engaged by said means on said shaft;

10. A pressure responsive controller for use in a fuel dispensing system having a selector valve, a shaft for rotating the selector valve and means for rotating said shaft, said controller comprising a movable member,- pressure responsive means operatively connected therewith and fluid connected with the fuel dispensing system for response to changes of pressure therein, a control device carried by said movable member and operable to operative position when said'movable member moves in one direction, operable to remain in operative position and to-be moved bodily by said movable member when it moves in an opposite direction, and means on said shaft for rendering said control device inoperative when the last means assumes a position corresponding to a new selector valve position, said control device being operatively connected with said means for rotating said shaft-to render it operative by decrease of pressure in said pressure responsive means to a' predetermined value, said means for rotating said shaft being rendered inoperative in response to said means on said shaft, providing said pressure responsive means has-in the meantime responded to an increase in fuel pressure sufficient to'move said movable member to a position where the operative control device tlfiereof may be engaged by said means on said s aft.

11. A pressure responsive control device for use in a fuel dispensing system having a'selector valve and means for changing the position thereof, said pressure responsive device comprising a carriage, pressure responsive means connected with the fuel-dispensing system so as to be responsive to pressure or absence of pressure therein and operable to move said carriage in one direction uporidecrease of pressure and man opposite direction'upon increase of pressure in said fuel system/a controller for'said means carried by said carriage and operable to operative position when said carriage is moved'in said first mentioned direction as a result of fuel pressure decrease; saidcontroller remaining operative and being moved bodily by said carriage when said carriage moves in said oppositedirection as a result of fuel pressure increase, said controller being rendered inoperative by said means when it causes said selector valve to assume a new selector valve position. v

12. A pressure responsive switch for use in a fuel supply system for an engine having a super-.

pressure responsive means connected with the fuel supply system so as to be responsive to pressure therein, said pressure responsive means beingin communication with said 1 supercharger fonmodificationof the position of the pressure responsivemeans .in response to'variation's in pressure produced by thesupercharger, said pressure responsive meansbeing operatively'connected with said switchrcarriage, a switch carried by saidswitch carriage andoperable' to closed'position by engagement with an abutment sure responsive switch comprising a switch carfirst mentioned direction, said switch being openable to remain in said one position and to be movedbodily by said switch carriage when the when said switchcarriage moves in one direction as are'sult of fuel pressure decrease and superv charger pressure increase, said switch being operable to remain closed and to be moved bodily by-said switch carriage when said carriageamoves in'the'opposite direction as a result of fuel pressure increase and supercharger pressure idesv crease, said switch being. opened'by: said-means for changing-the position of said selector valve when'said means assumes-a newselector valve position and said switch being operatively con- 1 'nected to 'the circuit of said means to energize the samein response to closing of said switch.

'13.-.A pressureresponsive switch for use in a fuel'dispensing system having a selector valve and solenoidroperated ratchet means .for changin'gthe position of said selector-valve, acontrol switch for the circuit of saidsolenoid, a switch carriage, pressure responsive means connected with thepfuel dispensing system so as to be responsive to the pressure of fuel therein and operable to move said switch carriage in one direction or an opposite direction as a result of fuel pressure changes, said control switch being carried by said switch carriage, a stationary abutment, said control switch being operable to closed position by engagement with said stationary abutment when said switch carriage moves in said first mentioned direction, said control switch being operable to remain closed and to be moved bodily by said switch carriage when it moves in said second mentioned direction, said switch being opened bysaidsolenoid ratchet operated means when it assumes a new selector valve position.

14. A pressure responsive switch for use in a fuel supply system for an engine having a supercharger, said system having a selector valve and electrically operated means for changing the position of the selector valve, said switch comprising a switch carriage, pressure responsive means for operating said switch carriage and connected with the fuel supply system so as to be responsive to changes of pressure therein, said pressure responsive means being in communication withsaid supercharger for modification of the position of said switch carriage in response to variations in pressure produced by the supercharger, a control switch carried-by said switch carriage, a stationary abutment thereadjacent, said control switch being operable to closed position by engagement with said stationary abutment when said switch carriage moves in one direction, operable to remain closed and to be moved bodily by said switch carriage when said carriage moves in the opposite direction, and

opened by said means for changing the position of said selector valve when said means assumes a new selector valve position and said switch effecting control of the circuit of said means.

15. A pressure responsive switch for use in a fuel dispensing system having a selector valve and solenoid operated ratchet means for changcarriage moves in said second mentioned direction. said switch being moved to its other position by said solenoid ratchet operated means of said'selector valve when it assumes a new selec-, tor valve position and being operable to energize the circuit of said. solenoid when in saidone position: and to deenergize it when in said other position. I I .a Y

7 l6. A-pressure responsive switch 'for controlling electricallvoperated meansfor changing the, position of a selector valve of a fuel dispensing system, said pressureresponsive switch comprising a movable member, pressureresponsive means responsive to pressure of said fuel dispensing system andoperable to move said movable member in one direction upon decrease of fuel pressure ing the position of said selector valve, said presand in an opposite direction upon increaseof fuel pressure, a switch carried bysaid movable member and connected in circuit with said electricallyoperated means to energize the samein response to closing of said switch, said switch being operable to closed position by movement of said movable member in said first mentioned direction as a result of fuel pressure decrease, said switch being operable to remain closed upon bodily movement with said movable member when it moves in said opposite direction as a result of fuel pressure increase, said switch being opened by said electrically operated means when it assumes a new selector valve position.

17. A pressure responsive switch for use in a fuel dispensing system having a selector valve, said switch comprising a bellows chamber responsive to fuel pressure, a second bellows chamber, a movable switch carriage, the bellows of said chambers being operatively connected therewith for moving it in one direction by increase of pressure in the first bellows chamber and decrease of pressure in the second one and for moving it in the opposite direction by deoperable with said selector valve to be changed to said initial position thereby when said valve assumes a position of registry.

18. A pressure responsive switch for use with an engine having a supercharger and a fuel dis pensing system having a selector valve compris- I ing a bellows chamber responsive to fuel pressure, a second bellows chamber responsive to supercharger pressure, a movable switch carriage, the bellows of said chambers being operatively connected therewithfor moving it in opposite directions by increase and decrease of pressure in said bellows chambers, a switch adapted to be carried bodily by said switch carriage, an abutment to engage said switch and move it to direction, said carriage when moving in the pposite direction carrying said switch with it without moving the switch to open position and the switch being cooperable with a selector valve of the fuel dispensing system to be opened thereby in a predetermined position of said selector valve. 19. In a pressure responsive switch for use in a fuel dispensing system having a fuel tank selector means, a bellows chamber responsive to fuel pressure, a movable switch carriage, the bellows of said chamber being operatively connected therewith to move said carriage in one direction by increase of pressure in said bellows chamber and to move it in the opposite direction by decrease of pressure in said bellows chamber, a switch adapted to be carried bodily by said switch carriage, an I abutment to engage said switch and change the position thereof when the carriage moves in one direction, said car-- riage when moving in the opposite direction being ineffectual to change said switch to its initial position and the switch being cooperable with said fuel tank selector means to be changed to said initial position thereby.

- 20. In a pressure responsive switch for use in a fuel dispensing system of an engine having a supercharger, a bellows chamber responsive to fuel pressure, a movable switch carriage, the

closed position when the carriage moves in one bellows of said chamber being operatively connected therewith to move said carriage in, one, direction by increase of pressure in said bellows chamber and to move it in the opposite direction by decrease of pressure in said bellows chamber, a switch adapted to be carried bodily by said switch carriage, an abutment to engage said switch and change the position thereof when the carriage moves in one direction, said carriage when moving in the opposite direction being ineffectual to change said switch to its initial position and the switch being cooperable with a fuel tank selector means of the fuel dispensing systemto be changed to said initial position thereby, and means responsive to supercharger pressure for modifying the response of said switch carriage to said fuel pressure bellows.

21. A fuel pressure responsive switch for use in a fuel dispensing system having selector means said switch being provided with contactor element mounted upon a carriage movable with respect to its body portion such that each occurrence of predetermined fuel pressure drop automatically locks said contactor element in closed circuit position and that each subsequent pressure rise advances said locked contactor element into a prearranged position from which it may be disengaged by said selector means.

- DAVID SAMIRAN,