US2446335A - Control apparatus for internalcombustion engines - Google Patents

Description

L. LEE, 2D

.Aug. 3, 948.

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CONTROL APPARATUS FOR INTERNKL-COMBUSTION ENGINES 3 Sheets-Sheet 2 Filed June 29, 1945 mun C6 .uvmvron Lag/17m [55' H Asgm Aug. 3, 1948.

L. LEE, 2D

CONTROL APPARATUS FOR INTERNAL-COMBUSTION ENGINES 5 Sheets-Sheet 5 Filed June 29, 1945 w TOR. if y/W0 [55H r x. A

AGENT Patented Aug. 3, 1948 v CONTROL APPARATUS FDR INTERNAL- COMBUSTION ENGINES Leighton Lee, 11,

of New Jersey West Hartford, Conn., assignor, by mesne assignments, to Company, West Hartford, Conn,

Niles-Bement-Pond a corporation Application June 29, 1945, Serial No. 602,282

21 Claims. 1

The present invention relates to apparatus for controlling the supply of fuel to internal combustion engines, and particularly to control apparatus for a fuel supply system of the type including aset of pumps for injecting liquid fuel into the individual cylinders of an internal combustion engine, orinto the intake manifold near the individual ports of the cylinders.

An object of the present invention is to provide improved means for controlling the quantity of fuel pumped per stroke in such injection pump mechanism.

Another object is to provide improved apparatus for controlling such pumpmechanlsm during starting of the engine.

Another object is to provide improved means for controlling such injection pump mechanism under idling or light-load conditions.

A further object is to provide, in injection pump control apparatus having two types of control mechanism, one for normal running, and the other for special operating conditions as starting or idling, improved mechanism for transferring control from one to the other of the two con trolling devices.

A further object is to provide, in a fuel supply control system including a pump delivery control shaft and a shaft used during engine operating conditions as a mixture control shaft, a clutch between the two shafts, a spring biasing the clutch to engaged position and means responsive to the fuel pressure provided by an engine driven pump for releasing the clutch, so that-the pump delivery may be manually controlled by the mixture control shaft when the engine is not running and so that the pump delivery control mechanism is released from the mixture control shaft as soon as the engine starts to run.

Another object of the present invention is to provide improved valve means for controlling a fluid motor in response to the relative positions of two control elements, so that the motor may be made to position one of the elements in accordance with the position of the other. v Other objects and advantages of the present invention will become apparent from a consideration of the appended specification, claims and drawings, in which Figure 1 illustrates, somewhat diagrammatisally,- a fuel supply system for an internal combustion engine, including control apparatus embodying certain features of my invention,

Figure 2 is a somewhat diagrammatic illustration of a, modified form of fuel supply control mechanism, including certain additional features of my invention, as well as modified forms of certain of the features shown in Figure 1,

Figure 3 is a view taken along the line 3'3 of Figure 2, looking in the direction of thearrows,

Figure 4 is a'vlew taken along the same line as Figure 3, but looking in the opposite direction, as

indicated by the arrows 4-4 in Figure 2,

Figure 5 is a view of a selector valve shown in Figure 2, but with the parts in a different position,

Figure 6 illustrates a modified form of hydraulic motor which may be used in place of that shown in Figure 2, and

Figure 7 is a cross-sectional view taken along the line l'l of Figure 6.

Figure 1 There are shown in Figure 1 a portion of the air induction system of an internal combustion engine, a portion of the fuel supply system including injection pump mechanismand means for controlling the delivery of the injection pump mechanism. The delivery control means includes means responsive to the rate of air flow thru the air induction system, which controls the pump delivery under normal engine operating conditions. The pump delivery control mechanism also includes means for manually controlling the pump delivery when the engine is not running,.as under starting conditions, and means for controlling pump delivery in accordance with the throttle position under idling or low load conditions.

Referring to Figure 1, there is shown an air conduit Iii, thru which air flows from an entrance l2, past a venturi l4, and an air flow controlling throttle valve it to an outlet it. From the outlet I8, the air usually passes thru a supercharger into the engine intake manifold. Such a super- "charger is commonly used on aircraft engines,

and the present fuel supply control system is particularly designed for use on aircraft engines, although its utility is not so limited. In some cases, a supercharger may also be used upstream from the entrance l2. According to the wellknown laws of fluid flow thru a Venturi meter, a pressure differential is'established between the entrance I! and the throat of venturi l4, which pressure differential varies with the square of the velocity of the air flowing thru the venturi M. This pressure differential is used to create a flow of air thru a secondary air passage which may be traced from a plurality of impact tubes 20' whose ends are open to the impact of the enteringair, thru a conduit 22 interconnectingthe impact tubes 28, a boost venturi 24, a chamber 28, past a valve 28 and thru a throat of venturi I4.

The valve 28 is positioned by a flexible bellows 32, which forms one wall of an expansible sealed chamber 34. The chamber 34 is filled with a fluid having an appreciable coefficient of thermal expansion, so that the position of valve 28 varies in accordance with the pressure and temperature inside the bellows 32. If required, a suitable spring or springs may be added to cooperate with bellows 32 in positioning valve 28.

The valve 28 varies the fiow thru the secondary air passage in accordance with the density of the air, so that the pressure differential between the entrance and throat of the boost venturi 24 varies conduit 38 to the substantially in accordance with the mass of air flowing per unit time thru passage I8, rather than in accordance with the velocity of the air fiow. This density or altitude compensatingeflect is completely described and claimed in the copending application-of Milton E. Chandler Serial No. 890,281, filed June 10, 1943, now Patent No. 2,393,144, issued Jan. 15, 1946, and assigned to the assignee of the present application.

The pressures at the entrance and throat of the boost venturi 24 are communicated thru conduits 38"and 38'respectively, to chambers 48 and 42, respectively, in a control valve unit generally indicated at 44.

The chambers 48 and 42 are separated by a flexible diaphragm 48. The control valve unit 44 also includes an expansible chamber 48 separated from the chamber 48 by a flexible diaphragm 58, and an expansible chamber 52 separated from chamber 42 by a flexible diaphragm 54. The diaphragms 58, 46 and 54 are connected at their centers to the stem 58 of a valve 58.

Fuel for the engine comes from a tank (not shown) and flows thru a conduit 88, a boost pump 82, usually driven by an electric motor, a transfer pump 84, usually engine driven, thru a conduit 68, past an idle valve 88, thru a jet system and mixture control unit generally indi cated at '18, a conduit 12, a recirculating venturi I4, a. conduit I8, a vapor trap I8, a conduit 88, to a fuel injection pump generally indicated at 82. Fuel from the pump 82 flows thru a plurality of conduits, one of which is shown at 84, to the cylinders of the engine.

The pump 82 is of more or less conventional design, and includes a plurality of plungers, one for each engine cylinder. One of the plungers is shown at 88 and is reciprocated by a cam 88 driven by the engine. The plunger 88 may be rotated by means of a rack 38 which engages va pinion 82 on the plunger. The plunger 88 is provided with a. contoured recess in its lateral surface which cooperates with an inlet port 84 and a spill-over port 98. The angular position of the plunger 88 in its associated cylinder determines the point in the travel of the plunger at which the closure of inlet port 84 takes place. The spill-over port 98 is always opened at the same point in the plunger travel. When either of these ports is opened, the pressure ahead of the plunger is relieved, and no pumping action thru the check valve 85 to conduit 84 takes place. When both ports are closed and the plunger is moving toward the right, the pumping action takes place. Therefore, rotation of the plunger 88 by the rack 98 determines the quantity of fuel pumped per stroke of the plunger. Fuel discharged thru the spi1l-over port 96 passes thru a conduit 38, a vapor trap I88 and a conduit I82 to the throat of the recirculating venturi 14. The purpose of the recirculating venturi and the vapor trap I88 is to make sure that all vapor bubbles are removed from the fuel after its turbulent passage thru the spill-over port before it is again supplied to the pump inlet.

The jet system and mixture control I8 includesa fixed restriction I84, a fixed restriction- I88, ,a restriction I88 controlled by a valve II8 biased to closed position by a spring H2, and a restriction II4 controlled by a valve I I6, which is biased open by a spring H8 and closed by a cam I28 on a mixture control shaft I22. The end of shaft I 22 also carries a ported sleeve I24 which cooperates with a ported seat I28, and which may be used to cut oil the flow of fuel to the conduit I2. The shaft I22 may be positioned by a suitable manual lever I23.

When the mixture control shaft I 22 is in the position illustrated. fuel may flow only thru restriction I84. If the fuel pressure differential across the jet system I8 is high enough, valve I I8 will open, allowing an additional flow or fuel. The valve H8 is therefore termed an enrichment valve.

The shaft I22 may be rotated to a position the influence of spring II8. This is known as the rich position of the mixture control, since fuel can then flow thru both restrictions I84 and H4. In both the positions of the mixture control so far described, the ports of the sleeve I24 and the seat I 28 are aligned so that the cut-01f valve does not restrict the flow of fuel to the engine.

For a given area of the metering restriction open to the flow of fuel, the pressure differential across the jet system I8 is a measure of the rate of flow of fuel to the engine. The pressure in the fuel line at the upstream side of the jet system is communicated thru conduit I32, a chamber I34, a conduit I38, a restriction I38, and a conduit I48 to the chamber 52 of the control valve unit 44. Fuel pressure at the downstream side of the jet system is communicated thru a conduit I42 and a restriction I44 to the chamber 48 of the valve control unit 44.

From the foregoing, it may be seen that an air pressure differential acts downwardly on diaphragm 48 with a force which is a measure of the mass of air flowing to the engine per unit time. At the same time, the fuel pressure differential across the jet system acts on diaphragms 54 and 58. Since the fuel pressure under diaphragm 54 is higher than the pressure above diaphragm 58, the fuel pressure differential provides a net upward force. Under steady conditions, these two forces are balanced, indicating that the fuel flow is proportioned to the air flow, and valve 58 remains in the central position indicated in the drawing.

The position of rack 98 which controls the delivery of the injection pump 82 is determined by a gear I48 engaging rack 98 and fixed on shaft I48. The shaft I48 is rotated by a. fluid servomotor generally indicated at I58. Motor I58 includes a piston I52 reciprocating in a cylnider I 54 and separating two opposed expansible chambers I 58 and I58 formed between the piston and theopposite ends of the cylinder. The piston I52 is connected by a rod I88 to a crank arm I 82 attached to shaft I48.

Shaft I48 carries a clutch member I84, which is notched as in I68 to receive a tooth or projection I88 on a shiftable clutch member I18.

I10, so that it is always engaged with notch I88.

The oppositeend ofsmember I carries a pro-..

iection I12 which is movable into engagement with a notch I14 formed in a helical gear I16 which is freely rotatable on the shaft I48. I'he gear I16 mates with a gear I18 fixed on the mixture control shaft I22. The shiftable clutch member I10 is movable by means of a shifting lever I18 pivoted at I80 and having its opposite end pivotally connected to a rod I82. The rod I82 is provided with a crater in its opposite end. In this crater rides a conical tip formed on the end-of a valve stem I81. The stem I81 is attached to the center of a diaphragm I84. A spring I86 holds the rod I82 against stem I81. The right side. of diaphragm I86 is exposed to the. pressure in chamber I34, which is the same as the fuel pressure on the upstream side of the Jet system. The spring I86 biases the diaphragm I84 for movement to the right against the pressure in chamber I34. The chamber at the left of diaphragm I84 is vented to atmosphere thru the aperture around stem I82. If a time delay in the, motion of diaphragm I84 is desired. it may be provided and controlled by properly designing the vent aperture.

Operation of Figure 1 When the parts are in the positions shown in the drawing, the engine is running, and the fuel pressure in chamber I34has moved the diaphragm I84 to the left, compressing the spring I86 and'tilting the lever I18 so as to move projection I12 out of the notch I14. Therefore, rotation of mixture control shaft I22 turns the gear I16. freely on shaft I48 and does not aifect the position of the pump delivery control rack 90.

When the engine stops, the pump 64 stops and the fuel pressure in chamber I34 consequently drops until it can no longer overcome the spring I86, which thereupon moves diaphragm I84 to the right and moves the shiftable clutch member I10 t the left engaging the projection I12 with notch I14. If the tooth I12 and notch I14 are 'not aligned, they can be aligned by manual movement of the mixture control lever I23 until the tooth snaps into the notch. Rotation of mixture control shaft I22 then causes gear I16 to rotate the clutch member I10 and the clutch member I64, and the latter being fixed on the shaft 148, the shaft rotatesalso, changing the position of the pump capacity control rack 80. At the same time, a valve I88, attached to the center of diaphragm I84, is moved to the right, opening a by-pass connection between chambers I56 and I50. This by-pass connection maybe traced from chamber I56 thru conduits I90, I82 and I94, past valve I88 and thru conduit I96 to chamber I58. This by-pass connection prevents a hydraulic locking of the piston I52, making the piston easily movable with the shaft I48 as the latter is manually moved by the rotation of mixture control shaft I22.

The pressure at the discharge side of boost pump 62 is regulated by a relief valve generally indicated at 59, biased to closed position by a spring 6| whose strength determines the boost pumpdischarge pressure. The discharge pressure of the transfer pump 64 is controlled by a relief valve generally indicated at 65, biased to closed position by a spring 61. The spring. 61

of the reliefvalve 64 is made stronger than the springtl of relief valve 59, so that when the ensine driven. pump 64 is running, the pressure at its-discharge outlet is greater than when only the boost pump 62 is running. The two springs 6| rid 61 are so coordinated with spring I86 of the clutch controlling mechanism that the clutch will not be operated to release the pump delivery control shaft I48 from the mixture control shaft I22 when the only fuel pressure is that supplied by the boost pump. When the engine driven pump 84 starts to run, the pressure increases to the higher. value determined by spring 61, which provides a sufficient force acting on diaphragm I84 to compress spring I86 and operate the clutch mechanism. As previously pointed out, a time delay may be provided to prevent diaphragm I84 from operating the clutch on a sudden pressure surge, thus ensuring that the engine. is running steadily before the clutch is operated.

The pumps 62 and 64 are provided with bypass valves 63 and 68, respectively, which allow fuel to be pumped past either one of the pumps by the other-pump, .if the one pump is not running.

With the engine running, if the air flow increases, the increased pressure differential acting on'diaphragm 46 move the valve 58 downwardly, thereby allowing fuel to flow from the downstream side of the jet system thru conduit I42, restriction I44, conduits I98 and 200, past the valve 58 and thru a conduit 202 to chamber I56. At the same time. chamber I58-is connected thru a conduit 204, past valve 58 to a drain conduit 206 which leads to the fuel intake conduit 60. Therefore a pressure diifer'ential is estab lished on piston I52, causing the latter. to be moved to the left, rotating shaft I48 clockwise. moving the rack downwardly. This rotates the pinion 92 and plunger 86 so as to increase the delivery of the pump 82, thereby increasing the fuel flow. Motion of the piston I56 to the left continues until the fuel flow has increased sufiiciently so that the fuel pressure differential acting upwardly on valve 58 balances the downwardly acting air pressure differential.

I The lower end of valve 58 is subject to the same pressure as the upper end of stem 56, this pressure being supplied thru the lower end of valve 58 thru conduits I88 and 208. This makes the net diaphragm area subject to the down! ward pressure in chamber 48 equal to the net diaphragm area subject to the upward pressure in chamber 52.

If for any reason the fuel pressure differential exceeds the air pressure differential, the valve 58 is moved upwardly. Fuel then flows from the upstream side of the jet system thru the conduit I32, chamber I38, conduit I36, restriction I38, conduit 2I0, past valve 58 and thru conduit 204 into chamber I58. At the same time, chamber I56 is connected thru conduits I90 and 202, past valve 58 to drain conduit 206. A pressure differential is thereby applied to piston I52 which moves it to the right, thereby rotating shaft I48 counter-clockwise and moving the pump delivery control rack 90 in a delivery decreasing direction. This movement continues until the fuel flow has decreased by an amount sufficient so that the fuel pressure differential again balances the air pressure differential and valve 58 is restored to its neutral position.

The restrictions I36 and I44 provide a means for anticipating the response of the pump capacity control to the movements of the control valve 58 so as to restore thevalve 58 to its normal posi-.

tion more quickly, thereby preventing over-shooting and hunting of the control system. For example, when the valve 58 moves downwardly, fuel flows thru the restriction I44 to the chamber I56. This produces a drop in pressure on fore the actual pressure differential across the jet system I is increased by the action of the pump delivery control mechanism.

Similarly, when the valve 58 is moved upwardly, in a fuel flow decreasing direction, the fuel supplied to the servo-motor I50, flows thru restriction I36, thereby reducing the pressure in chamber 52 in proportion to the rate of flow thru restriction I38. This reduction in pressure in chamber 52 anticipates the final reduction in the fuel pressure differential which will result from the operation of the servo-motor I50, and therefore operates to dampen the response of the system and to prevent hunting and over-shooting.

It has been found that the valve 58 is more sensitive and provides a better control when the lands which cover the ports leading to conduits 202 and 204 are made just slightly smaller than those ports. However, under such conditions there will be a slight leakage thru the valve 58 to the drain passage 206 at all times. Since this leakage might come from either the upstream or downstream side of the jets, it might upset the fuel metering of the system. To avoid upsetting the fuel metering, while retaining the desired sensitivity of the valve, I have provided a small leakage restriction 2I2 in the conduit I92 which leads from chamber I34 to conduit I90. Thru the restriction 2I2, a small amount of fuel at high pressure is continuously supplied to chamber I56. This tends to move the servo-motor piston I52 in a fuel flow increasing direction, and as a result, the control valve 58 establishes its normal position at a point where the conduit 202 is provided with a slight leakage space to the drain conduit 206. This allows the high pressure fuel supplied thru restriction 2i 2 to pass out to the drain conduit 206 without disturbing the position of the piston I52. Under low air flow conditions, such as are encountered at idling and low engine loads, the air pressure differential applied to diaphragm 46 may not be an accurate measure of the air flow, because of the large area of the passage I0 as compared to the small quantity of air then flowing. Under such conditions, it is necessary that additional means be provided to regulate the fuel flow. The means provided are the idle valve 68, which is connected to the throttle to operate concurrently therewith and the spring 49, which acts on the valve 58 in a fuel flow increasing direction. The spring 49 is chosen so that its force is small as compared to the forces due to the air and fuel pressure differentials which act on the valve 58 under normal running conditions. The effect of spring 49 is then negligible. However, under low air flow conditions, the force acting downwardly on diaphragm 46 practically disappears, so that the force of spring 49 becomes the predominatlng force controlling the valve 56. It tends to move the valve in a fuel flow increasing direction. At the same time, the valve 60 is moved toward closed position as the throttle approaches its closed position. The contour of valve 68 and the strength of spring 40 may be selected to give any desired variation of fuel-to-air ratio with throttle position under idling conditions. As soon as the 8 throttle moves out of the range of positions near its closed position, the valve 66 is retracted so that it no longer obstructs the fuel flow.

Figure 2 There is shown in Figure 2 a modified form of fuel injector pump delivery control mechanism. In Figure 2, those elements which correspond fully to their counterparts in Figure 1 have been given the same reference numerals, while elements which have no counterparts in Figure 1 have been given new reference numerals in the 300 to 599 series.

The air induction and measuring system of Figure 2 corresponds generally to that of Figure 1.

There is shown an air induction passage I0, a

density compensatingvalve 26, and a fixed restriction 302 which replaces the boost venturi 24 of Figure 1. The control valve unit 44 corresponds generally to the control valve 44 of Figure 1.

The pump 64 of Figure 2 is provided with a relief valve 304 which cracks open slightly at low pump discharge pressure against a weak spring 306. However, in order to open sufficiently to pass any appreciable quantity of fuel, the pump dis charge pressure must overcome a stronger spring 308. The purpose of this dual spring arrangement will be described later.

Fuel flows from the pump 64 in Figure 2 thru a conduit 3I0 thru a mixture control 3I2, conduits 3 and 3I'6, a jet system M3 and thence thru a conduit 320 to a number of fuel injection pumps, one of which is shown at 62.

Th mixture control 3I2 includes a disc valve 322 fixed on a shaft 324. When the valve 322 is in the full line position shown in the drawing, fuel can flow only thru the conduit 3 I4 to the jet system 3I8. When the valve 322 is in the dotted line position, fuel can flow thru either of the conduits 3I4 and 3I6. The full line position is known as the lean position of the mixture control and the dotted line position is known as the rich position. The mixture control is operated by a lever 3I3 attached to shaft 324, and may also be moved to a cut-ofi position wherein fuel cannot flow thru the conduits 3l4 and 3I6.

Fuel passing thru the conduit 3 may flow either thru a fixed restriction 326 or a restriction 328 controlled by a valve 330, which is biased to closed position by a spring 332. Fuel passing thru conduit 3I6 flows thru a restriction 334. The fuel passing thru the restrictions 326 and 334 must also pass through a fixed restriction 336. Restriction 326 corresponds to restriction I02 of Figure 1. Restriction 336 corresponds to restriction I06 of Figure 1. Restriction 320 and valve 330 correspond to restriction I08 and valve IIO of Figure 1. Restriction 334 corresponds to restriction I I 4 of Figure 1. The valve 322 performs both the functions of valves I I6 and I24 of Figure 1, since it may selectively open and close the conduit thru restriction 334 just as valve II6 selectively opens and closes the path of fuel flowing thru restriction I I4 of Figure 1. It may also operate to completely cut off the fuel, similarly .to the cut-off action of valve I24 of Figure 1.

A cam 338 on the throttle shaft 340 cooperates with a follower 342 on a crank arm 344 attached to shaft 346. A helical gear 348 is fixed on the shaft 346 and cooperates with another helical gear 350 fixed on a sleeve 352 surrounding an extension of the mixture control shaft 324. The sleeve 352 and shaft 324 are confined between upper and lower castings 354 and 356.

At its end opposite the gear 350 the sleeve 352 332 to a port which opens into an annular'recess.

366 formed in the castings 364 and 356. The port 392 is connected thru a passage 368 drilled in sleeve 362 to a similar annular recess 318jformed in the castings 364 and 366. The recesses 366 and.318 are connected to conduits 312 and 314,

respectively. Beyond the valve member 388', another sleeve 316 surrounds the shaft 324. At its left end, the sleeve 316 carries a valve member 318 having a face which slidingly engages the face of the valve member 368. The face of valve 313 is provided with a pair of spaced arcuate grooves 388 and 382. The groove 388 communicates with a passage 384 drilled thru the sleeve 316 and leading to an annular recess 366 formed in the castings 364 and 366. The groove 362 communicates with a passage 388 drilled thru the sleeve 318, which leads to the upper end of a cylinder 388 formed in the castings 368 and 364. A passage 392 connects the annular recess 388 with the lower end of the cylinder 398. A piston 394 95 reciprocates within the cylinder 388 and separates it into upper and lower chambers 338 and 398. The piston 394 and the cylinder 398 together form a fluid servo-motor generally indicated by the reference character 483. The piston 394 is attached to a rod 482 connected thru a link 484 to a crank arm 488 attached to the sleeve 318.

A. chamber 463 is formed in the castings 354 and 363. Inside the chamber 486, the sleeve 316 carries a helical gear cm, which mates with another helical'gear M2 fixed on a shaft 4. The shaft 4 also carries a gear 4i8 which engages with and positions the delivery control rack 98 of the injector ump 62.

The servo-motor 488 is operated by fuel under pressure, which is taken from the main fuel conduit 3l8 thru a branch conduit M8. The servomotor 486 may be controlled either by the control valve unit 44 or by the valve members 383 and 318, depending upon the position of a selector valve mechanism generally indicated at 428. The selector valve mechanism 428 includes a diaphragm 422 separating a pair of expansible chambers 424-and 426 andattached at its center toa spool valve 423. The diaphragm 422 is also connected to the center of a spring disc 438. A compression spring 432 is retained between the spring disc 438 and the left hand end of the casing 434 in which the diaphragm 422 is mounted. The spring disc 438 is provided to give a snap action of the diaphragm and valve 428 between the position shown in the drawing hereinafter referred to as the "air flow controlled position and another position wherein the valve 426 blocks the passage of fuel between conduits 464 and 466, and between conduits 468 and 416, which other posiengage the slot 444. thereby coupling the shaft 324 and the sleeve 316 to rotate together. The disc 448 is connected thru a coupling shown diagrammatically at-468 to a diaphragm 462. The coupling 468 may be of any suitable type which will permit rotation of the disc 448 relative to the diaphragm 462. The diaphragm 462 separates a pair of expansible chambers 464 and 433. A spring 468 in the chamber 466 biases the diaphragm in a direction to cause plate 448 to enge both slots 442 and 444. The chamber 468 is vented to atmosphere, as shown at 468. The size of the vent 468 may be controlled as desired to give the clutch mechanism a timedelay characteristic. The chamber 484 is connected thru a conduit 482 to conduit 6 containing fuel at high pressure. When the engine is running, the pressure in chamber 464 is sumcient to overcome spring 458 and move the diaphragm 462 and plate 446 to the position shown in the drawing, so as to disengage plate 446 from slot 444, whereby the shaft 324 and the sleeve 618 may then rotate relative to each other.

Qperation ofFioure 2 When the parts are in the positions shown in the drawing,v the engine is running, and the fuel pressure in chamber 454 has compressed the spring 456 to release the plate 446 from engagement with slots 444 on the sleeve 316. The fuel pressure differential across the jet system acting on the diaphragm 422 is sufficient to hold valve 426 in the position shown, wherein the control valve unit 44 is in control of the servo-motor 488. If the air flow now increases, the force acting on diaphragm 46 of the control valve unit 44 ins creases moving valve 69 to the right. This allows fuel at highpressure to flow from conduit 4w thru valve 59, conduit 464, past valve 428, thru conduit 4166 and passage 392 to the chamber 398 below piston 394. At the same time, the chamher 396 above piston 3941s connected thru a conduit 468, past valve 428, thru a conduit 418, past valve 59 and thru a conduit 412 to drain'conduit 414; Therefore a fluid pressure difierential is applied to the piston 394m a direction to move it upwardlythereby rotating the sleeve 316 to operate the pump delivery control mechanism thru the gears 418, M2 and H6 in a delivery increasing direction. This movement continues until the fuel pressure-differential across the jet system has increased sufliciently to restore the valve 69 to its neutral position as shown in the drawing.

' Ifthe air flow decreases, the control valve unit 44 operates to connect chamber 396 to the high pressure conduit 4 I 8 and chamber 398 to the drain conduit 414. This causes a downward movement of a piston 394 to operate the pump delivery control in a decreasing direction. 5

If it is assumed that the throttle i6 is moved toward closed position and that the fuel pressure tion is hereinafter referred'to as the throttle controlled"'position. Chamber 426 is connected thru a conduit 436 and conduit M8 to the fuel line on the upstream side of the jet system. The chamber 424 is connected thru conduits 438 and v 448 to the fuel line on the downstream side of the I the slot 442, and may be moved to the left from the position shown in the drawing so as to also differential decreases correspondingly until the force acting on diaphragm 422 is not suflicient to maintain the spring disc 438 in the position illustrated, then the disc 438 snaps to a new position, shown'in- Figure 5, moving the valve 428 to a position where it blocks the flow between conduits 464 and 466 and also betweenconduits 468 and 418. but opens paths of flow between conduits 436 and 312 and between conduits 314 and 414;

The servo-motor 488. is then controlled by the valve members 358 and 318. The valve member 363 is positioned by the throttle, and the operavalve member 318 is driven by the servo-motor until it reaches an angular position corresponding to that of valve 358, which depends upon th position of throttle l8 and the contour of cam 338. When the parts of valve 28 are in the positions shown in Figure 5, fuel at high pressure will flow from conduit 8 thru conduit 438, chamber 428, conduit 312, recess 388, passage 384, groove 388, passage 384, recess 388, and conduit 382 to chamber 388 below piston 384. At the same time, chamber 388 above piston 384 is connected thru passage 388, groove 382, passage 388, recess 318, conduit 314, past valve 428, to drain conduit 414. Therefore the pump delivery control mechanism is operated in a delivery increasing direction, and the sleeve 318 is, rotated in a counterclockwise direction as viewed from its right end. This motion of piston 384 and sleeve 318 continues until the lands between the ends of grooves 388 and 382 and valve member 318 are aligned with the ports 388 and 382 in the valve member 358. When this occurs, the fuel passages to both chambers 388 and 388 of the servo-motor are blocked and it stops.

It may be seen that when the engine is running in the normal range of power output conditions that the fuel pressure differential is determined by the air pressure differential. Therefore, the point at which the selector valve mechanism 428 operates to shift control of the servo-motor 488 from the control valve unit 44 to the valve members 358 and 318 is determined by the rate of flow of air to the engine. On the other hand, the point at which the selector valve mechanism moves in the opposite direction is determined by the throttle position and by the cam 338 rather than by the rate of air flow. By properly contouring the cam 338, it is possible to insure that the selector valve mechanism 428 will not shift from its throttle controlled position to its air flow controlled position until the air flow has increased to a point where the fuel pressure differential thereafter established by the air flow control valve unit 44 will be sufficient to maintain the selector valve in its air flow controlled position. Likewise, it can be assured that the selector valve will not shift from its airflow controlled position to its, throttle controlled position until the throttle has moved far enough toward closed position that the selector valve mechanism will thereafter stay in its throttle controlled position until the throttle is again opened. It has been found that by proper contouring of the cam 338, the change-over may be made to take place at substantially the same value of air flow in both directions. This mode of operation is aided by the well-known characteristics of a snap action a mechanism such as the spring disc 438 by which such devices require a smaller force to maintain them in their snapped position than they require to move themto that position.

When the engine is not running, the spring 458 moves the plate 448 to the left. Thereafter, the fuel pump delivery may be controlled by positioning the mixture control shaft 324, provided that the shaft 324 is first rotated back and forth as required to line up the slot 444 with the plate 448. The selector valve mechanism at such times will be in the position where the valve members 358 and 318 control the servo-motor 488. At such times, movement of the sleeve 318 by the mixture control shaft 324 will operate the piston 384 as a pump. It may be seen that the valve members 358 and 318 will give a detent action when the ports 368 and 382 are lined up with the grooves 388 and 382, since they will then block the flow of fuel pumped by the servo motor 384. By this means the pilot may know where the injector pump delivery control is set with respect to the throttle l8 and the cam 338. If the cam 338 is contoured to give the most efficient engine operation for a given throttle position, the pilot can tell by the detent action whether the injector pump delivery is being set leaner or richer than the most efficient position. If the detent action is found to be too severe, so as to prevent manual adjustment of the pump delivery control, it can be avoided by moving the throttles one way or the other when the detent action is encountered. This throttle movement will change the alignment between the ports 388 and 382 and the grooves 388 and 382 to eliminate the detent action.

The pump 84 is provided with a relief valve 384 which opens a short distance against a light spring 388 so that when the pump delivery control is being manually positioned the pressure established by the pumping action of the servomotor piston 384 is relieved thru that valve, thereby preventing a hydraulic locking of the movement of the pump delivery control.

Figures 6 and 7 I have shown in Figures 6 and! a modified form of hydraulic servo-motor which may be used in place of that shown in Figure 2. This servomotor is a gear type motor comprising a pair of mating gears 588 and 582. Fluid is supplied to and withdrawn from this motor thru passages 388 and 382, which correspond fully to the passages bearing the same reference characters in Figure 2. The flow of fluid thru these passages is controlled by the valve members 358 and 318. The valve member 318 is driven by the gear motor 588, 582. Both the valve members and the gear motor are capable of continuous rotation in either direction. Therefore, it may be seen that this type of valve mechanism and motor may be readily applied to any type of hydraulic control system where continuous rotation of the controlling or controlled devices, or both, is required.

While I have shown and described certain preferred embodiments of my invention, other modifications thereof will readily occur to those skilled in the art, and I therefore intend my invention to be limited only by the appended claims.

I claim as my invention:

1. A fuel supply system for an internal combustion engine, comprising injector pump mechanism, means for controlling the delivery of said pump mechanism, motor means for operating said delivery controlling means, a manually movable control device, clutch means selectively movable between a first position wherein said manual control device is connected to said delivery controlling means and a second position wherein said device and said controlling means are independently movable, spring means for biasing said clutch means toward said first position, and means responsive to operation of said engine for moving said clutch means to said second position.

2. A fuel supply system for an internal combustion engine, comprising means for controlling the rate of fuel supply to said engine, motor means for operating said control means, a manually movable control device, clutch means for connecting said manual control device to said fuel supply controlling means, and means responsive to operation of said engine for operating said 13 clutch means to disconnect said control device from said fuel supply controlling means.

3. A fuel supply system for an internal combustion engine, comprising a fuel pump driven by said engine for supplying fuel under pressure, means for controllingthe rate of fuel supply to said engine, motor means for operating said control means, a manually movable control device for operating said control means under starting conditions, clutch means for connecting said device and said fuel supply controlling means, and means responsive to the pressure of the fuel discharged by said pump to operate said clutch means to disconnect said device from said fuel supply controlling means.

4.A fuel supply system for an internal combustion engine, comprising injector pump mechanism, means for controlling the delivery of said pump mechanism, motor means for operating said delivery controlling means, a manually movable control device, clutch means selectively movable between a first position wherein said manual control device is connected to said delivery controlling means and a second position wherein said device and said controlling means are independently movable, said .delivery controlling means being operable thruout substantially its entire range of movement by said manual control device when said clutch means is in its first position, and means for operating said clutch means.

5. A fuel supply system for an internal combustion engine, comprising means for controlling the rate of fuel supply to said engine, motor means for operating said control means, a manually movable control device, clutch means for connecting said manual control device to said fuel supply controlling means, said fuel supply controlling means being operable thruout substantially its entire range of movement by said manual control device when connected thereto by said clutch means, and means for operating said clutch means.

6. A fuel supply system for an internal combustion engine, comprising a first fuel transfer pump for supplying fuel to said engine, electric motor means for driving said first pump to supply fuel when the engine is stationary, first relief valve means for regulating the discharge pressure of said first pump at a first predetermined value, a second fuel transfer pump driven by said engine for supplying fuel thereto, second relief valve means for regulating the discharge pressure of said second pump at a second predetermined value greater than said first value, injector pump mechanism for supplying fuel to the cylinders of said engine, conduit means for conveying fuel amass;

from said first and second pumps to said injector I pump mechanism, means for controlling the delivery of said injector pump mechanism, reversible motor means for operating said delivery controlling means, means responsive to the rate of flow of combustion air to said engine for controlling said reversible motor means, a manually movable control device, clutch means selectively movable between a first position wherein said manual control device is connected to said delivery controlling means and a second position wherein said device and said delivery controlling means are independently movable, means movable concurrently with said clutch means to .interrupt control of said reversible motor means'by said air ilow responsive means when said-clutch means is in said first position, spring means to bias said clutch means toward said first position, and means responsive to the pressure of the fuel supplied to said injector pump mechanism thru said conduit means and effective when said fuel pressure exceeds said second predetermined value to overcome said clutch biasing spring means and move said clutch means to said second position.

'7. A fuel supply system for an internal combustion engine, comprising a conduit for fuel flowing toward said engine, metering restriction means in said conduit, means for varying the pressure differential across said restriction means to vary the flow of fuel therethru, manual control means for varying the cross-sectional area of said restriction means, and clutch means for connecting and disconnecting said manual control means and said pressure differential varying means, said manual control means and said pressure differential varying means being independently movable over substantially their entire ranges of movement when said clutch means is disengaged,

and said pressure differential varying means being movable by said manual control means over substantially its full range of movement when said clutch means is engaged.

8. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for supplying fuel to the cylinders of said engine, a fuel conduit for conveying fuel to said injector pump mechanism, a metering restriction in said conduit, means for varying the delivery of said pump mechanism, a fluid motor for operating said pump delivery varying means including two expansible chambers separated by a movable wall. a valve responsive to the fuel pressure differential across said-metering restriction for controlling the flow of fluid to said chambers, said valve being effective upon an increase in said fuel pressure differential to connect one of said chambers to said fuel conduit on the upstream side of said restriction and to connect the other chamber to a drain, and upon a decrease in said fuel pressure differential to connect said other chamber to the fuel conduit on the downstream side of said restriction and to connect saidone chamber to the drain, and a passage including a fixed restriction extending from the fuel conduit on the upstream side of said meterin restriction to said other chamber so that under equilibrium conditions all fuel passing thru the valve to the drain is supplied from the upstream side of the metering restriction.

9. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for delivering fuel to the cylinders of said engine, means for controlling the delivery of said pump mechanism, motor means for operating said delivery controlling means, a conduit for combustion air flowing to said engine, means for measuring the flow of combustion air thru said conduit. throttle means for controlling the flow of air thru said conduit, first motor control means operated by said air flow measuring means, second motor control means operated concurrently with said throttle means, and selector means responsi e to the rate of flow of fuel to said engine for selectively placing said first and second motor control means in control of said motor means.

10. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for delivering fuel to the cylinders of said engine, means for controlling the deliver of said pump mechanism, motor means for operating said' deliver controlling means, a conduit for combustion air flowing to said engine, means for measuring the flow of combustion air thru said conduit, throttle means for controlling the flow of air thru said conduit, a conduit for fuel flowing to said pump mechanism. a metering restriction in said fuel conduit. first motor control means responsive to said air now measuring means and to the fuel pressure differential across said metering restriction and effective to control said motor means and thereby the delivery of said pump mechanism to maintain said fuel pressure differential substantially proportional to the rate of air flow, second motor control means, cam means movable with said throttle means for operating said second motor control means, selector means movable between first and second positions wherein said first and second motor control means, respectively, are in control of said motor means, snap action spring means associated with said selector means for biasing the same toward said second position, and a diaphragm subject to said fuel pressure differential for operating said selector means in opposition to said spring means, said spring means being effective when said fuel pressure differential falls below a predetermined value to move said selector means to said second position, and retain it there until said pressure differential increases to a substantially higher value, said cam means being contoured to cause an increase in the delivery of said pump mechanism and thereby an increase in said fuel pressure differential at a throttle position generally corresponding to an air flow just greater than that corresponding to the said predetermined value of fuel pressure differential.

11. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for delivering fuel to thecyllnders of said engine, means for controllin the delivery of said pump mechanism, motor means for operating said delivery controlling means, a conduit for combustion air flowing to said engine, means for measuring the flow of combustion airthru said conduit, throttle means for controlling the flow of air thru said conduit, first motor control means operated by said air flow measuring means, second motor control means operated concurrently with said throttle means, selector means for selectively placing said first and second motor control means in control of said motor means, a manually movable control device, clutch means selectively movable between a first position wherein said manual control device is connected to said delivery controlling means and a second position wherein said device and said controlling means are independently movable, spring means for biasing said clutch means toward said first position, and means responsive to operation of said engine for moving said clutch means to said second position.

12. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for delivering fuel to the cylinders of said engine, means for controlling the delivery of said pump mechanism, fluid mbtor means for operating said delivery controlling means, a conduit for combustion air flowing to said engine, means for measuring the flow of combustion air thru said conduit, throttle means for controlling the flow of air thru said conduit, first control valve means operated by said air flow measuring means, second control valve means operated concurrently with said throttle means, selector means for selectively placing said first and second control valve means in control of said motor means, a manually movable control device, clutch means selectively movable between a first position wherein said manual control device is connected to said bustion engine,

for moving said clutch means to said second position, said second control valve means comprising cooperating'valve members which block the passage of fluid thru said motor means at corresponding positions of said motor means and said throttle, said blocking of the fiuid providing a detent action when said controlling means is operated by said manually movable control device.

13. A fuel supply system for an internal combustion engine, comprising injector pump mechanism for delivering fuel to the cylinders of said engine, means for controlling the delivery of said pump mechanism, fluid motor means for operating said delivery controlling means, means including a first hollow shaft connecting said motor means and said delivery controlling means, a throttle for controlling the flow of combustion air to said engine, a second hollow shaft aligned with said first shaft, and connected to said throttle for concurrent movement therewith, cooperating valve members connected to said first and second shafts for controlling said motor means to cause said first shaft to follow the movements of said second shaft, a manually rotatable shaft extending thru both said hollow shafts,- and clutch means for connecting said manually rotatable shaft to said first hollow shaft so that the delivery of said pump mechanism may be manually controlled.

14. A'fuel supply system for an internal comcomprising injector pump mechanism for supplying fuel to said engine, means for controlling the delivery of said pump mechanism, a manually movable throttle for controlling the flow of combustion air to said engine, means responsive to the rate of flow of combustion air to said engine for operating said pump delivery control means, and manual means for operating said pump delivery control mechanism during engine starting conditions independently of said late of air flow and independently of the position of said throttle.

15. A fuel supply system for an internal combustion engine, comprising means for controlling a the rate of fuel supply to said engine, motor means for operating said control means, a manually movable control device, clutch means for connecting said manual control device to said fuel supply controlling means, means responsive to operation of said engine for operating said clutch means to disconnect said control device from said fuel supply controlling means, and time delay means for preventing such disconnection until the engine operation has continued for a predetermined time.

16. A fuel supply system for an internal combustion engine, comprising a fuel pump driven by said engine for supplying fuel under pressure, means for controlling the rate of fuel supply to said engine, motor means for operating said control means, a manually movable control device for operating said control means under starting conditions, clutch means for connecting said device and said fuel supply controlling means, means responsive to the pressure of the fuel discharged by said pump to operate' said clutch means to disconnect said device from said fuel supply controlling means, and time delay'mcans for preventing such disconnection until the pump has discharged fuel for a predeterminedtime.

when open to terminate control of said motor means by said control valve, and means responsive to a condition of engine operation for operating said by-pass valve. 1

18. A fuel supply system as in claim 17, in which said fuel flow controlling means comprises injector, pump mechanism, and means for varying the delivery of said injector pump mechanism.

19. A fuel supply system as 'in claim 17, in which said condition responsive means is responsive to the pressure of fuel flowing to said engine, and is effective when said fuel pressure falls below a predetermined value to open said by-pass valve.

20. A fuel supply system as in claim 17, including manual means for operating said fuel control means when said by-pass valve is open.

21. A fuel supply system for an internal combustion engine, comprising means for controlling the rate of flow of fuel to said engine, fluid motor means for operating said fuel control means ineluding a pair of expansible chambers separated by a movable wall, a source of fluid under pressure, manual means for operating said fuel flow control means, control valve means for selectively connecting said chambers to said source to cause operation of said fluid motor means, or for connecting said chambers to each other to prevent interference with said manual means by said motor means, and means responsive to a condition of engine operation for operating said control valve means.

LEIGHTON LEE, II.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS lished May 18, 1943.

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