US2864597A - Fuel carbureting system - Google Patents

Description

FUEL CARBURETING SYSTEM Michael A. Arpaia, Glendale, Calif. Application February 28, 1956, Serial No. 568,237

25 Claims. (Cl. 26l47) This invention relates to fuel and air control devices for internal combustion engines as used on motor-driven vehicles and more particularly to an automatic device responsive to manifold pressure conditions to perform various functions chief among which is to prevent all fuel flow to the engine during deceleration and coasting downgrade. Ot-her important functions include the supply of auxiliary air under certain other operating conditions to assure a leaner fuel mixture and substantially complete combustion of the fuel and to break the manifold vacuum during deceleration.

It is well known that carburetion systems of vehicle engines pass excessive quantities of fuel to the cylinders during certain operating conditions and particularly during deceleration and while the engine is being driven by the car during descent of grades. This condition exists notwithstanding the fact that the accelerator pedal is released by the driver to close the carburetor throttle valve to a point intended to admit only suflicient fuel for engine idling requirements. However, the engine is then rotating faster than idling speed and, in consequence, the manifold pressure is reduced below normal idling pressure and this causes excessive quantities of fuel to flow past the throttle valve to the engine. The excess fuel is only partially burned and discharges, in part, past the piston walls to dilute and contaminate the crank case oil and, in part, through the exhaust system to the surrounding air in the form of noxious fumes. Numerous attempts have been made heretofore to prevent the delivery of excess fuel to the engine as well as to provide a properly proportioned combustible fuel and air mixture under normally encountered operating conditions. However, none appear to have been sufficiently reliable and effective to warrant incorporation as a part of the original equipment for a modern automobile.

In view of the foregoing factors and conditions characteristic of fuel-and-air control devices for vehicle engines of the internal combustion type, it is a primary object of the present invention to provide a new and improved device suitable either for incorporation as an integral part of a carbureting device or as an accessory to carburetors presently in service, and operable to prevent all fuel flow to the engine during deceleration or coasting.

Another object of the present invention is to provide a carburetor accessory responsive to manifold pressure to actuate fuel and air control mechanisms in a manner supplementing and overriding, under certain operating conditions, the fuel-and-air control provided by the usual engine carburetor.

Still another object of the invention is to provide pressure-responsive means subject to engine manifold conditions for actuating a plurality of valves to effect control of fuel and air flow to an internal combustion engine in accordance with actual power requirements, and which additionally provide positive fuel cut-off during deceleration and descent of grades, together with automatic means for regulating the manifold pressure during deceleration.

Yet another object of the invention is to provide an nitecl Sttes atent G 'ice automatic fuel shut-off device for discontinuing all fuel flow to the engine during deceleration in combination with means for restoring fuel flow for engine idling requirements while the vehicle is still under way.

Still another object is the provision of auxiliary means for automatically regulating the combustion air supply to the engine cylinders during substantially all power supply operating phases and particularly during acceleration and cruising.

A further object of the invention is the provision of automatic means for breaking the manifold vacuum and maintaining the same at a desired optimum value somewhat below the manifold idling pressure while the vehicle is coasting as well as substantially throughout deceleration of the engine.

Yet another object of the invention is to provide a simply constructed, compact accessory device adapted for insertion between the usual carburetor and manifold without the need for auxiliary or supplemental connections and operating in response to manifold pressure conditions to cut off all fuel flow to the engine as the manifold pressure falls in response to the throttling of the fuel and air flow while decelerating or coasting.

These and other more specific objects will appear upon reading the following specification and claims, and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

Figure l is an elevational view of a fuel and air carbureting device incorporating the present invention with portions of the casing broken away in different planes to show constructional details, the parts being positioned in their full open engine acceleration position;

Figure 2 is a fragmentary elevational view of the device shown in Figure 1 showing the position of the auxiliary air inlet valve and of the actuating mechanism therefor during motor idling operation;

Figure 3 is a view similar to Figure 2 but showing the position of the auxiliary air inlet valve and associated parts during deceleration of the engine;

Figure 4 is a view similar to Figure 3 showing the position of the auxiliary air inlet valve and associated parts during normal cruising operations;

Figure 5 is a cross-sectional view along line 55 on Figure 1 showing the air filter screen and retaining cover in place;

Figure 6 is a longitudinal sectional view through one of the pair of fuel cut-off valves showing the valve in mid-position as it is being opened suddenly by the operator by depression of the accelerator pedal; and

Figure 7 is a showing of the pivoting actuator lever interposed between the cutofr valves and the manifold pressure-responsive actuating means therefor as seen from the line 77 of Figure 1.

Referring again to the drawing, a conventional fuel and air carbureting device is generally designated 10 and has its air inlet 11 connected to a suitable air cleaning device 12. The usual butterfly valve 13 is mounted on a shaft 14 pivotally supported crosswise of the carburetor fuel and air discharge passage 15. Rigidly secured to the outer end of shaft 14 is a bell crank 16 having one arm connected to a suitable linkage 17 extending to a foot accelerator pedal, not shown. It will be understood that the conventional throttle valve 13 is rotatable through approximately degrees between its fully open position shown in Figure 1 and a nearly horizontal closed position in which it passes only sufficient fuel and air for engine idling requirements.

The lower flanged end 18 of the carburetor would in the usual engine be connected directly to the similarly flanged intake end 19 of the engine manifold generally indicated at 20 and understood to be of any suitable type for distributing the fuel and air mixture to the intake valves of the engine cylinders. As herein shown, however, the carburetor has been disconnectedfrom manifold flange 19 and elevated sufficiently to receive the housing of the automatic fuel cut-off and auxiliary air control device, generally designated 21, of the present invention. p

The automatic fuel cut-off and air control device 21 will be seen to comprise a generally L-shaped, tubular housing having a vertical extension 22 and a horizontal extension 23 closed at its left end, as viewed in Figure l, and opening downwardly through a short vertical duct 24. The lower end of duct 24 has a flange 25 adapted to be clamped to the similarly flanged intake end 19 of manifold 20. A second short duct 26 projecting upwardly from leg 23 has a flanged end 27 adapted to be clamped to flange 18 of the carburetor discharged duct as by fastening means 28, it being understood that similar fastening means not shown may be used to secure flanged end of lower duct 24 to the manifold.

The short upper duct 26 is of elliptical shape in cross section, the minor axis being shown in Figure 1 and the major axis being at right angles thereto and normal to the plane of the drawing. Duct 26 provides a housing for a pair of poppet-type cut-off valves 31 identical to the single valve shown in Figure l. Valves 31 are arranged in spaced relation along the major transverse axis of the duct and have stems 32 extending slidably through openings in L-shaped bracket means 33 integral with a partition 29 extending across the lower end of the duct 26. This partition is provided with a large opening for each cut-off valve, the upper edge of each opening being chamfered to form a seat for the associated cut-off valve. Encircling each valve stem 32 is a coil spring 34 sized to contact the under surface of valve 31 after the valve has been closed to the dotted line poistion shown in Figure l, and which is of a strength to support the valve in that position in which it is spaced fromits seat 30 sufficiently as topermit the flow of a volume of the fuel mixture sufficient to meet the fuel requirements of the engine during idling. During engine deceleration valves 31 seat upon their seats 30 and compress springs 34, as will be explained more fully presently.

Referring now to the auxiliary air admission valve mechanism and the pressure-responsive means for controlling both this mechanism and cut-off valves 31, it will be observed that the vertical leg 22 of tubular housing 21 has an upper bore 35 of slightly greater diameter than the lower end of the leg to provide a shoulder 36 seating a disc 37 formed with a central guide opening 38. A piston is secured to the threaded lower end of stem 39 bye. nut 41, the stem above the piston seating slidably 1n its guide seat 38 in disc 37. The upturned peripheral edges of piston 40 provide a smooth sliding fit with the interior wall of the piston chamber 42 formed below disc 37 in tubular housing 22. The piston is urged at all times to the upper end of the chamber 42 by an expansion coil spring 43 surrounding piston stem 39 and having its lower end seated on disc 37 and its upper end bearing against a washer 44 adjustably retained on threaded upper end of the stem by a nut 45. Access to nut 45 may be had by the removal of a cap 46 threaded to the end of housing extension 22. The upper end of the piston chamber 42 is preferably vented to the atmosphere through openings 47 immediately below disc 37.

The auxiliary air inlet facility will be best understood by reference to Figures 1 and 5 wherein it will be observed that the lower forward face of housing extension 22 is provided exteriorly with a chamber formed by an integral circular wall 48 having a threaded end to receive a ring forming a part of an air filtering screen 49. The inner side of chamber 50 is formed by a flat wall 51, part of housing extension 22, which has a circular air inlet passage 52 near its left peripheral edge, as viewed in Figures 1 to 5, and a larger, generally-rectangular port or passage 53 diametrically spaced therefrom. Controlling the air fiow through ports or passages 52 and 53 is a ported circular valve disc 54 fixed to the outer end of a shaft 54 rotatably supported crosswise of housing extension 22. Valve disc 54 is provided with three air inlet ports angularly disposed about its axis and arranged to be brought into registry with the stationary passages 52 and 53 upon the rotation of the disc. These three ports include a circular cruising air inlet 55, a relatively large, generally sector-shaped deceleration air inlet 56, and a relatively small radially-elongated acceleration air inlet 57.

Pivotally supported by pin 59 for movement around the outer face of valve disc 54 is a sector-shaped toggle plate valve member 58 having ears 60, 61 projecting from its outer corners, which are adapted, under certain circumstances, to abut a stationary stop pin 62 carried rigidly by the bottom wall 51 of housing 50 adjacent the rim of disc valve 54. A pair of stop pins 63 and 64 project outwardly from valve disc 54 upon opposite sides of toggle member 58 to limit the latters pivotal movement about pivot pin 59 under the action of a tension spring 65 connected between a pin 66 on valve disc 54 and a pin 67 on toggle member 58, as shown in Figure 5, as the member 58 pivots sufficiently to move the spring on center with respect to its own pivot 59.

The auxiliary valve disc 54 and its supporting shaft 54' are adapted to be reversibly rotated to different operating positions by a lever 68 having its mid-portion fixed to shaft 54 and its upper end pivotally connected to the lower end of the piston stem 39 by a link 69. The opposite end of lever 68 is connected pivotally to a link 70 extending downwardly through housing extension 22 and pivotally connected to a hole 71 in the right-hand end of a lever 72 extending lengthwise through housing extension 23 and pivotally supported therein on a transverse pivot shaft 73. Projecting from the lower forward corner of lever 72 is a shelf 78 which underlies the forked right end 75 of a T-shaped actuator lever 76, the latter being pivotally connected to lever 72 by a transverse pin 77. The described arrangement provides a knee-action joint which limits the counterclockwise movement of actuator 76 with respect to lever 72 while allowing the actuator 76 to move clockwise relative thereto for a purpose to be explained presently. Referring to Figure 7, it will be seen that the opposite lateral ends of T-shaped actuator lever 76 underlie the ends of valve stems 32 of the cutoff valves 31, the valve members proper being indicated by dot and dash circles.

Under certain operating conditions it is desirable to open cut-off valves 31 manually, as for example when the operator wishes to accelerate during a period of deceleration. Provision for such manual opening is illustrated in Figures 1 and 6, and comprises a shaft 79 suitably supported for rotation in a boss 80 protruding from the left-hand end of housing extension 23. A radial lever arm 81 secured to the outer end of shaft 79 is connected through link 82 to arm 83 of hell crank 16, which, as previously described, is fixed to the projecting end of the throttle valve shaft 14. Projecting radially from the inner end of shaft 79 is a cam 84 centered below the head of the T-shaped actuator lever 76. It is to be understood that the release of a conventional accelerator pedal, not shown, allows the spring thereof to pull link 17 upwardly to close throttle valve 13 crosswise of passage 15. This same movement is effective to move link 82 downward to rotate shaft 79 and swing cam 84 from its position shown in Figure 1 in which it has held the valve 31 in raised position.

Operation When the engine is not operating, atmospheric pressure conditions will prevail in the carburetor, in the manifold and in the pressure-responsive device 21, and spring 43 of the latter will be effective to hold piston 40 in its uppermost position close to the underside of disc 37. Air port 57 in disc valve 54 will be opposite passage 53 and cut-off valves 31 will be elevated to a maximum open position. The usual accelerator pedal spring will also be effective on linkage 17 and 82 to hold throttle valve 13 substantially closed across the carburetor discharge passage 15 and cam 84 will be rotated out of contact with the actuator lever 76, the latter being held elevated by levers 72 and 76.

In starting the engine, the operator depresses the accelerator thereby elevating link 17 and opening throttle valve 13 as the engine is turned over by the starter, the cut-off valves 31 then being held fully open by spring 43 in the manner described above. Assuming that the engine is allowed to idle after starting, throttle valve 13 will be in its so-called closed position across passage 15 wherein it permits passage of sufficient fuel and air for engine idling requirements. This substantial closure of the throttle valve results in low-speed engine rotation and a low pressure condition in the intake manifold 20 and in the housing of the pressure-responsive mechanism 21 connected thereto. Normally, the suction pressure in the manifold under engine idling conditions is roughly equivalentto a 20-inch column of mercury. For convenience, the manifold pressure reduction while the engine is operating may be termed manifold depression and reference hereinafter made to a manifold depression of 15, 20 or the like, will be understood to mean a manifold suction pressure of 15 and 20 inches of mercury, respectively. It will be understood that typical manifold suction pressures measured in inches of mercury for an engine employing the present invention are as follows for the respective operating conditions: idling operation, 20 inches suction; cruising, 15 to 17 inches suction; acceleration, 0 to 15 inches suction; deceleration, 17 to 23.

In view of these wide-range manifold pressure fluctuations, it will be apparent that piston 40 will reciprocate through a considerable range and will effect a corresponding angular range of movement of the auxiliary air control valve 54. This circumstance taken with the fact that it has been found advantageous to admit widely different quantities of auxiliary air to the manifold under different engine operating conditions and no auxiliary air under other conditions, makes it desirable to employ a multiple ported valve operable to control the flow of air through a pair of spaced air passages of different sizes for reasons which Will become apparent as the operation is described.

While the engine is idling, spring 43 should be adjusted by means of nut 45 until a manifold depression of 20 acting upon the exposed lower end of piston 40 is effective to maintain the auxiliary valve disc member 54 in the position illustrated in Figure 2. In this position the three movable air ports 55, 56 and 57 are out of alignment with fixed air passages 52 and 53 underlying valve disc 54 and no auxiliary air is being admitted to housing 22. Also, so long as the engine is idling, piston 40 will be effective through link 69, lever 68, link 70, lever 72 and actuator 76 to hold cut-off valves 31 in the dotted line position illustrated in Figure 1 with their lower surfaces resting against the upper end of springs 34 to admit only sufiicient fuel and air for engine idling requirements. It is characteristic of this relationship, as is apparent from a consideration of Figure 2, that all three ports of valve 54 are closed and no auxiliary air is admitted to housing 22 by valve disc 54 during engine idling operation, and also the adjustment of idling spring 43 is such that the lower radial edge of deceleration air port as is spaced slightly counterclockwise from the upper radial edge of air passage 53.

Let it next be assumed that the operator desires to increase the engine speed and depresses the accelerator pedal. This elevates connecting link 17 and rotates shaft 14- of throttle valve 13 to open the fuel-and-air discharge passage 15 of carburetor 10, and simultaneously pulls link 82 upwardly to rotate shaft 79, pivoting cam 84 upwardly against actuator lever 76 and opening cut-off valves 31 to a position corresponding to that of the throttle valve. Due to the knee-action joint between levers 72 and 76, the resulting upward movement of the actuator lever has no effect on lever 72, the auxiliary air valve 54 or piston 40. Immediately following the opening of the throttle and the cut-off valves 31, however, the manifold suction drops allowing spring 43 to elevate piston 40 and rotate valve disc 54 counterclockwise to an extent dependent upon the degree to which the throttle valve is opened to admit air to the manifold. For example, if the accelerator pedal is depressed to open the throttle valve widely for fast acceleration, the manifold depression rises (that is, the suction drops) to a value approaching atmospheric pressure thereby allowing spring 43 to elevate the piston and rotate valve disc 54 to the position shown in Figure 1 wherein acceleration port 57 overlies air passage 53. This allows auxiliary air to flow into housing 22 and manifold 20 to provide a leaner gas mixture and to assure adequate air for complete combustion of the large quantities of fuel being admitted to the engine during rapid acceleration. While the valve disc is in this position, link 70 will act through lever 72 and actuator 76 to hold cutoff valves 31 in their fully open positions wherein they offer little or no obstruction to the free flow of the air and fuel mixture into the manifold.

As the engine picks up speed, the manifold depression will increase in value (that is, the suction increases) allowing the atmospheric pressure acting on the upper side of piston 40 through openings 47 to move the piston downwardly compressing spring 43. As this occurs, the piston acts through link 69 and lever arm 63 to rotate shaft 54' and the valve disc 54 secured thereto clockwise to move acceleration air port 57 out of registry with air passage 53, the toggle valve member 58 moving along with the disc, it being understood that during full acceleration operation the upper edge of the toggle valve member 58 is held against the stop 63 by tension spring 65. While valve member 58 lies against stop 63, car 60 of the toggle member can by-pass the right-hand face of stationary stop 62. Continued clockwise movement of disc 54 will bring lower ear 61 into contact with stop 62 and pivot toggle member 53 counterclockwise about its pivot 5? until ear 60 contacts the upper edge of stop 62 where it is held by spring 65. Normally, the engine will have reached a cruising speed as the parts reach the positions just described and the manifold suction pressure will continue to range between 15 and 17. Under these conditions, valve 54 and toggle member 58 will be in the position illustrated in Figure 4 in which cruising air inlet port 55 registers with passage 52 and toggle member 58 overlies the lower portion of port 55. inas much as the manifold pressure varies in accordance with the cruising speed it will be apparent that the position of piston 4-0 and of valve members 54 and 53 will oscillate to vary the amount of auxiliary air admitted through port 55 to the fuel mixture flowing to the engine. This auxiliary air serves to provide a slightly leaner fuel mixture and greater assurance of complete combustion of the fuel. It will be understood that if the manifold suction is 12 or less, toggle member 58 pivots clockwise to close port 55 and prevent stalling of the engine. If the manifold suction pressure increases to 15, disk 54 rotates clockwise to a position wherein ear 61 engages stop 62 to pivot member 58 counterclockwise until ear (in rests against stop 62, as illustrated in Figure 4 to admit auxiliary air through port 55 and passage 52 and again provide a leaner fuel mixture.

If the operator withdraws his foot from the accelerator pedal while the engine is operating at cruising, throttle valve 13 closes to admit only the idling fuel requirements. This substantial closing of the air inlet to the manifold caused a marked manifold depression to a value appreciably below 20 due to high rotating speed of the engine, and it is not uncommon for the manifold depression to fall to a value of 25. This low suction pressure in the manifold moves piston 40 to its lowest position in chamber 42, as illustrated in Figure 3. In moving to this extreme lower position, the piston 40 acts through the linkage mechanism connected therewith to pivot actu ator 76 downwardly and out of contact with the stems 32 of the cut-off valves, this being permitted by cam 84 held fully retracted by the closing of throttle valve 13. The extremely low manifold depression prevailing during engine deceleration is effective to lower cut-off valves 31 tightly against their seats 30 in opposition to spring 34 with the result that no fuel can flow to the engine during deceleration. Referring to Figure 3, it will be noted that the deceleration port 56 overlies air passage 53 to admit a relatively large volume of auxiliary air for the purpose of preventing excessive depression of the manifold suction pressure.

A further and important function of port 56 is to cooperate with piston 40 and spring 43 to maintain the manifold at a minimum suction pressure slightly below the manifold depression during engine idling. As will be apparent from a consideration of Figure 3, a lowering of the manifold depression will lower piston 40 and rotate port 56 clockwise to increase the volume of air admitted to the manifold through port 56, thereby breaking the suction slightly and allowing port 56 to close slightly. It will, therefore, be appreciated that a substantially equilibrium condition can be maintained in this manner while the engine is decelerating. In addition, the manifold pressure is held somewhat below the normal value of 20 for engine idling for the purpose of maintaining the cutoff valves fully closed and in opposition to springs 34. As the engine rotating speed approaches engine idling speed, the manifold suction decreases and the springs 34 will be effective to open the cut-off valves to the dottedline engine idling position shown in Figure 1, and allow idling fuel-and-air to flow to the manifold.

An operation similar to that described immediately above occurs at times during which the accelerator pedal is released and the motor vehicle is coasting downgrade. Under these conditions the engine will decelerate very slowly since the momentum of the vehicle is effective through the wheels, drive shaft and transmission to rotate the engine faster than during normal deceleration and causing an abnormal depression of the manifold pressure below 20 and the closing of the cut-off valves in opposition to springs 34 until such time as the engine rotational speed approaches a normal idling speed. As the manifold depression rises from a value of 22 or 23 toward an engine idling value of 20, springs 34 are effective to open the cut-off valves and allow fuel flow for engine idling requirements.

Let it now be assumed that the operator wishes to accelerate rapidly from a starting point at which the engine is decelerating and the manifold depression is near a maximum (that is, the suction is great). The operator merely depresses the accelerator to elevate link 17 and rotate throttle valve 13 toward its fully open position. The same movement of the accelerator acts through link 82 to rotate shaft 79 in a direction to rotate cam 84 into contact with the underside of actuator lever 76 thereby forcibly elevating the cut-off valves against the suction effect of the manifold depression. This upward movement of the actuator lever 76 does not affect the position of lever 72 nor of the piston nor of the valve disc 54 due to the presence of the knee-action connection provided between actuator 76 and the lever 72. The wide opening of the throttle and cut-off valves 13 and 31, respectively, allows fuel and air to flow at a maximum rate into the manifold to supply the requirements for full acceleration. As the manifold depression rises abruptly toward atmospheric pressure allowing spring 43 to move piston 40upwardly to bring the auxiliary air ports to 'the fullacceleration position illustrated in Figure 1.

Under these conditions, acceleration air port 57 overlies air passage 53'to admit additional air to the manifold, thereby providing a leaner fuel mixture and assuring complete combustion of the fuel.

During the transition from deceleration to full acceleration, toggle valve member 58 will pivot from a position against lower stop 64 to'its upper position against stop 63 in the following manner. As the manifold depression rises from a minimum value during deceleration to a maximum value during full acceleration, piston 40 moves upwardly in chamber 42 and rotates valve disc 54 counterclockwise. At the beginning of this counterclockwise movement, toggle spring 65 is effective to hold toggle member 58 against lower stop 64. Ear 60 of the toggle member then extends radially into the path of the underlying stop 62, as shown in Figure 3. As the disc rotates counterclockwise, stop 62 contacts car 60 and pivots the toggle member clockwise about its pivot 59 to overlie cruising air port in the valve disc. Further counterclockwise movement of the valve disc moves the center line of toggle spring 65 across the center of pivot pin 59 so that the spring is then effective to pivot the toggle member clockwise against upper stop pin 63. When so positioned, ear 60 lies radially inside the inner face of stop 62 so that valve disc 54 may be rotated counterclockwise to the Figure 1 position without interference from pin 62.

While the particular fuel-and-air control device herein shown and described in detail for use on internal combustion engines is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the present- -ly preferred embodiment of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. In a fuel carbureting system for an internal combustion engine of the type having a carburetor provided with a manually actuated throttle valve controlling the fiow of fuel and air from the carburetor to an engine intake manifold, that improvement which comprises a fuel cut-off valve in series with said throttle valve on the downstream side of the latter movable to a position positively cutting off all fuel flow to the engine, spring actuated linkage means for urging said cut-off valve to a fully open position, pressure-responsive means operatively connected to said linkage means having one side in communication with the atmosphere and the other in communication with said engine intake manifold and operable to close said cut-off valve in opposition to said spring to discontinue all fuel flow in response to a predetermined sub-atmospheric pressure in the manifold indicative of engine deceleration, and spring means operable to open said cut-off valve sufficiently to admit idling fuel requirements as the manifold pressure rises slightly above said predetermined pressure to indicate the approaching termination of a period of engine deceleration.

2. In combination with an engine intake manifold and a carburetor having a fuel-and-air passage discharging thereinto, a manually controlled throttle valve for said passage, automatic cut-off valve means for closing said passage in response to the depression of the manifold suction pressure below a predetermined value indicative of the initiation of a deceleration period of operation and to hold the cut-off valve tightly closed against fuel flow until near the close of the deceleration period, a cylindrical suction chamber in communication with said manifold and said automatic cut-off valve means, a piston freely movable along the inner wall of said chamber, spring means urging said piston to move in one direction but permitting the piston to move in opposition thereto in response to the lowering of the manifold suction in certain positions only of said piston and no auxiliary air in other positions of said piston.

3. The combination defined in claim 2 wherein said valve member for said auxiliary air passages comprises a rotary member having a plurality of ports therethrough arranged to register with certain of said air passages when said member is rotated to different positions by said piston and the linkage means actuated thereby.

4. The combination defined in claim 3 wherein said valve member for said auxiliary air passages includes a closure movably supported thereon for controlling the flow of auxiliary air through one of said valve member ports, and snap-action means operable to hold said closure in a position to admit air to said one valve member port while the manifold suction pressure is at a normal cruising rate value and for discontinuing the flow of auxiliary air therethrough at other manifold suction pressures.

5. In combination with an engine intake manifold and a fuel-and-air carburetor discharging thereinto under control of a manually operated throttle valve, a positive cut-off valve downstream from said throttle valve, spring means operable to bias said cut-off valve to a slightly open position to admit idling fuel at the end of a deceleration period of engine operation, said valve being movable to a fully closed position cutting olf fuel-and-air flow from the carburetor to the manifold in response to a determined pressure drop in the manifold following closure of said throttle valve to initiate a deceleration period, said predetermined manifold pressure being efiective to hold said cut-off valve closed until the manifold pressure rises slightly to indicate the approaching end of an engine deceleration period, said spring means being efiective at said slightly higher manifold pressure to open said cut-oil? valve to the extent required to admit idling fuel-and-air requirements, and spring-biased means responsive to higher manifold pressures for opening said cut-off valve fully to admit fuel-and-air from said carburetor under the sole control of said manually operated throttle valve.

6. In combination with an engine intake manifold and a carburetor having a fuel-and-air outlet discharging downwardly into the manifold, a manually operated throttle valve for regulating the flow through said outlet, a positive cut-off valve movable to closed position by gravity and located in said air outlet below said throttle valve, a cylindrical chamber opening to said manifold downstream from said cut-olf valve having a springbiased piston therein responsive to manifold pressure conditions, means extending between said spring-biased piston and said cut-off valve operable by said spring to hold the cut-oif valve open under pressure conditions normally prevailing in the manifold with said throttle valve open, said piston being movable in opposition to said spring in response to a predetermined low-pressure condition in the manifold to retract said means for holdingthe cut-off valve open and to permit the same to close by gravity and be firmly held there by the pressure differential acting on its opposite sides during the deceleration of the engine toward idling operation.

7. The combination defined in claim 6 including manually operable means movable to open said cut-off valve and break said predetermined low-pressure condition in the manifold independently of said spring-biased 1o piston and the valve holding means extending therefrom.

8. The combination defined in claim 7 wherein said manually operable means for opening said cut-off valve is connected to said manually operated throttle valve and is operable to break the low sub-atmospheric pressure in the manifold substantially simultaneously with the opening of the throttle valve.

9. The combination defined in claim 6 including means for admitting auxiliary air to said manifold selectively as determined by specific manifold pressure conditions measured by said spring-biased piston, said air-admitting means including a pair of spaced passages through the wall of said cylindrical chamber, a rotary plate member actuated by said piston overlying the ends of said passages having three ports of different sizes positioned to register with a particular one of said passages as said plate member is rotated by said piston and spring, the largest port and passage being in registry to admit a maximum of auxiliary air to said manifold following the closing of said throttle valve and during the deceleration of the engine, and said spring-biased piston being operable to move said ports out of registry with said passages and prevent the admission of auxiliary air to the manifold during engine idling operation.

10. The combination defined in claim 6 including means for admitting auxiliary air to said manifold under the cooperative control of said spring-biased piston and the prevailing manifold pressure conditions, said air-admitting means comprising a pair of passages through said chamber wall, a rotary plate operatively connected to said piston having a plurality of different sized ports positioned for registry with a particular one of said passages as said plate is rotated, the smallest one of said ports being adapted to be positioned over one of said passages by said spring-biased piston in response to a minimum manifold pressure depression and indicative of maximum acceleration operating conditions whereby additional air is supplied to provide a leaner fuel mixture and assurance of substantially complete combustion under high acceleration.

ll. An auxiliary air-admission device for use with a carburetor and intake manifold of an internal-combustion vehicle-propelling engine, said device comprising a chamber opening into the manifold and subject to the pressure fluctuations therein during different engine operating conditions, a plurality of passages through said chamber wall, a movable valve plate for opening and closing said passages selectively, a spring-biased piston in said chamber connected to said valve plate and responsive to a fall of the manifold pressure below a desired minimum value to move a larger one of said passages into and out of registry with one of said ports to maintain a predetermined low manifold pressure while the vehicle is decelerating, and said piston being responsive to a low manifold pressure indicative of acceleration conditions to move said valve plate to open a smaller one of said passages.

12. An automatic auxiliary air-admission and vacuumcontrol device for use between a carburetor and engine intake manifold, said device comprising a chamber opening into the manifold and subject to pressure fluctuations therein during different engine operating conditions, a pair of passages opening through said chamber wall, movable valve means having a cruising port, a deceleration port and an acceleration port movable selectively into and out of registry with at least one of said pair of passages, spring-biased piston means movably supported in said chamber operatively connected to said valve means, said piston and movable valve being responsive to manifold pressures and operable: to admit no auxiliary air under engine-idling manifold pressure conditions, to admit auxiliary air in definite but unequal amounts during full acceleration and during normally cruising conditions, respectively, and being operable to regulate the minimum 11 manifold pressure during declerating engine operating conditions.

13. An automatic auxiliary air-admission and vacuumcontrol device as defined in claim 12 wherein said movable valve means includes a spring-actuated snap-acting closure movable into and out of closing relation with respect to said cruising port, said closure member being operable in response to movement of said valve means to one position thereof to open said cruising portend admit auxiliary air to the manifold and being operable to prevent air flow through said cruising port at manifold pressures prevailing during other cruise operating conditions. 1

14. The combination with an internal combustion engine fuel supply of the type having a carburetor discharging a combustible fuel-and-air mixture to the engine manifold under the control of a manually operable throttle valve movable between a fully open position and a substantially closed position in the latter of which fuel for engine idling operation is admissibletherepast; of automatic means responsive to different manifold pressure conditions to admit controlled amounts of auxiliary air and to cut off all fuel flow to the engine during periods of engine deceleration, said automatic means comprising a housing between and communicating with both said manifold and the fuel-and-air discharge side of said carburetor, a cut-off valve controlling flow of fuel and air to said manifold, spring means operable to open said valve sufficiently to admit engine idling fuel requirements as said manifold pressure increases above a predetermined low value indicative of the approaching end of a period of engine deceleration but incapable of opening said cut-off valve so long as the manifold pressure is at or below said predetermined low value, auxiliary air-admission means for said manifold, and pressureresponsive means in communication with said manifold and connected to said auxiliary air-admission means, said pressure-responsive means being operable to adjust said air-admission means to maintain a predetermined low-pressure condition in the manifold during periods of engine deceleration and to break the vacuum and allow the pressure to rise above said low pressure as the engine deceleration approaches an engine-idling condition thereby allowing said springto open said cut-off valve and admit idling fuel to the manifold.

15. In combination with a carburetor having a fueland-air discharge passage adapted to be connected to an engine manifold, a manually controlled throttle valve for said carburetor, cut-off valve means downstream from said throttle valve comprising at least one reciprocally supported poppet'valve operable to hold the valve open to admit engine idling fuel in opposition to a manifold pressure indicative of engine idling conditions and permitting closing of the poppet valve so long as the manifold pressure is lower than under engine idling conditions and indicative of engine deceleration operation, springbiased piston means having one side subject to atmospheric pressure and its other side subject to the manifold pressure, the spring of said spring-biased piston being effective to hold said poppet valve open while said throttle valve is open and while the manifold pressure is only partially depressed as during engine rotating speeds above idling rotating speeds, and said piston being responsive to the manifold pressure depression resulting from closing of said throttle valve to effect closing of said poppet valve in opposition to said spring means urging the same open.

16. In combination with a carburetor having a fueland-air discharge passage adapted to be connected to an engine manifold subject to a minimum pressure during engine deceleration, a second but slightly higher pressure during engine idling and to a wide range of higher pressures during cruising and acceleration operating conditions; a manually controlled throttle valve for regulating fuel-and-air flow to the manifold; reciprocal cut-off valve means downstreamtfrom said throttle valve; a spring operable to open said cut-off valve to admit idling fuel therepast while said second pressure condition exists in the manifold but ineffective to hold the cut-off valve open when said minimum pressure conditions exist; and means operable bythe opening of said throttle valve to open said cut-ofi to permit the supply of fuel-and-air to the manifold.

17. The combination defined in claim 16 including automatically actuated means for admitting auxiliary air to the manifold during engine deceleration in quantities to prevent excessive pressure reduction in the manifold during deceleration but insufficient air to permit the manifold pressure to rise to said second minimum pressure indicative of engine idling conditions, said automatic means including a valved air inlet to the manifold controlled by spring-biased means responsive to manifold pressure conditions and operable to admit air in increasing amounts as the pressure falls below said engine-idling manifold-pressure conditions and operable to cut off auxiliary air flow as the engine approaches idling speed.

18. The combination defined in claim 16 including automatically actuated means for admitting auxiliary air to the manifold during rapid engine acceleration to provide a leaner fuel-and-air mixture, said automatic means including a valved air inlet to the manifold controlled by spring-biased means responsive to manifold pressure conditions and'operable to admit auxiliary air to the manifold only while the manifold pressure is near the higher pressure portion of said wide range of pressures prevailing during engine acceleration.

19. A fuel-and-air control accessory for connection between an engine manifold inlet and the discharge end of a fuel carburetor, said accessory comprising a tubular chamber having a piston reciprocably supported therein with one side adapted to communicate with a manifold inlet and the other side subject to atmospheric pressure, spring means for opposing the movement of the piston by manifold pressure, said chamber having an inlet adapted to be connected to the fuel-and-air discharge passage of a carburetor, poppet-type valve means for controlling flow through said chamber inlet, second spring means for urging said valve means open from the fully closed position thereof, linkage means connected to said piston and biased by said first-mentioned spring means to hold said poppet vlave fully open normally, auxiliary air inlet passage means in said tubular chamber, and movable portedvalve means operatively connected to said linkage means for controlling the admission of air through said passage means in accordance with the position of said springbiased piston.

20. In combination with a carburetor having a fuel and air discharge passage adapted to be connected to an engine manifold, a manually controlled throttle valve for said carburetor, cut-off valve means for controlling the flow of fuel to the manifold and comprising at least one reciprocally supported poppet valve operable to admit engine idling fuel in one position thereof in opposition to a manifold pressure indicative of engine idling conditions and permitting closing of the poppet valve so long as the manifold pressure is lower than under engine idling conditions and indicative of engine deceleration operation, piston means having one side subject to atmospheric pressure and the other side subject to the manifold pressure, means for biasing said piston in a direction and with a force sufiicient to hold said poppet valve open while said throttle valve is open and while the manifold pressure is only partially depressed as during engine rotating speeds above idling rotating speeds, and said piston being responsive to the manifold pressure depression resulting from closing of said throttle valve to etfect closing of said poppet valve in opposition to said biasing means urging the same open.

21. In combination with an engine intake manifold and a carburetor having a fuel and air outlet discharging into the manifold, a manually operated throttle valve for regulating the flow through said outlet, a positive cut-01f valve movable to closed position by gravity and located in the air passage containing said throttle valve, a tubular chamber opening to said manifold downstream from said throttle valve and having a piston therein inveluding means for biasing the piston in one direction,

means responsive to manifold pressure conditions for moving said piston in opposition to said biasing means, means extending between said piston and said cut-off valve operable by said biasing means to hold the cut-off valve open under pressure conditions normally prevailing in the manifold with the throttle valve open, said piston being movable in opposition to said biasing means in response to a predetermined low pressure condition in the manifold to retract said means for holding the cut-off valve open and to permit the same to close by gravity to cut off all fuel flow and to be firmly held there by the pressure differential acting on its opposite sides during the deceleration of the engine toward idling operation.

22. In combination with an engine intake manifold and a carburetor having a fuel and air passage extending therethrough, a manually controlled throttle valve for said passage, automatic cut-off valve means for closing said passage in response to the depression of the manifold suction pressure below a predetermined value indicative of the initiation of a deceleration period of operation and to hold the cut-off valve tightly closed against fuel flow until substantially the end of the deceleration period, a tubular suction chamber in communication with said manifold and said automatic cut-off valve means, a piston movable along the interior wall of said chamber, means urging said piston to move in one direction but permitting the piston to move in opposition thereto in response to the lowering of the manifold suction pressure to a first predetermined value, linkage means actuated by said piston for completely closing said cut-ofi valve means upon the lowering of the manifold suction pressure below a second determined value, a plurality of auxiliary air passages extending through the wall of said suction chamber, a ported valve member movably supported across said passages, means connecting said ported valve member to said linkage means for movement thereby, said air ports being of different size and so positioned with respect to said auxiliary air passages as to admit auxiliary air to the manifold in different quantities in certain positions only of said pistons and no auxiliary air in other positions of said piston.

23. In combination with an engine intake manifold and a carburetor having a fuel and air passage extending therethrough, a manually controlled throttle valve for said passage, positive cut-oflf valve means for positively discontinuing the flow of fuel in said passage in response to the depression of the manifold suction pressure below a predetermined value indicative of the initiation of a deceleration period of operation and to hold the cut-off valve tightly closed against fuel flow in said passage until the approach of the end of the deceleration period, a suction chamber in communication with said manifold and with said automatic cut-01f valve means, piston means movable along the interior wall of said chamber, means biasing said piston to move in one direction but permitting the piston to move in opposition thereto in response to the lowering of the manifold suction pressure to a first predetermined value, linkage means actuated by said piston for closing said cut-01f valve upon the lowering of the manifold suction pressure below a predetermined value, said cut-off valve being movable to an open position admitting fuel and air flow in said fuel and air passage as the manifold pressure indicates the approaching end of a deceleration period to admit fuel in an amount to maintain at least idling engine operation.

24. In a fuel and air supply mechanism for an internal combustion engine of the type having a suction manifold adapted to open into the cylinders of an engine and its intake in communication with a carburetor having a throttle valve controlling the flow of a fuel and air mixture to the manifold, that improvement which comprises, a normally open fuel valve connected in series with said carburetor throttle valve, and means operatively connected with said fuel valve and responsive to suction pressure conditions in said manifold for actuating the same, said last named means being effective to close said valve shutting off all fuel flow to the manifold during suction pressure conditions therein indicative of decelerating engine operating conditions and for holding said valve closed until the approach of the end of such operation.

25. A fuel and air supply mechanism as defined in claim 24 further characterized in the provision of means for admitting a limited quantity of auxiliary air to said manifold independently of said throttle valve and while the same is substantially closed.

References Cited in the file of this patent UNITED STATES PATENTS 1,956,992 Mallory May 1, 1934 2,017,878 Vanderpoel Oct. 22, 1935 2,057,215 Smith Oct. 3, 1936 2,107,863 Heinzelmann Feb. 8, 1938 2,186,989 Ostling Jan. 16, 1940 2,214,964 Leibing Sept. 17, 1940 2,269,496 Vanderpoel et al Jan. 13, 1942 2,395,748 Mallory Feb. 26, 1946

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