US2926892A

US2926892A - Fuel shut-off mechanism

Info

Publication number: US2926892A
Application number: US625720A
Authority: US
Inventors: Joseph T Wentworth
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1956-12-03
Filing date: 1956-12-03
Publication date: 1960-03-01
Anticipated expiration: 1977-03-01

Description

March 1, 1960 WENTWQRTH 2,926,892

FUEL SHUT-OFF MECHANISM Filed Dec. 3, 1956 IN VEN TOR.

A TTORNEY FUEL SHUT-OFF MECHANISM Joseph T. Wentworth, Royal Oak, Mich., assignor tov General Motors Corporation, Detroit, Mich, a corporation of Delaware The invention relates to a fuel shut-offmechanism and more particularly to a mechanism for interrupting the fuel supply to an internal combustion engine in order to side of the shaft 14 and connected through appropriate reduce the hydrocarbon emission by an automotive engine during decelerationt It is well known that automotive engines normally discharge appreciable quantities of unburned or partially unburned fuel during deceleration when the intake manifold vacuumis high. This high vacuum causes conditions to prevail in the engine combustion chamber that are not conducive to the complete combustion of the fuel and air mixture introduced. in

the chamber.

Various mechanisms have been proposed in the past which shut off the supply of fuel to the combustion chamber of an engine during deceleration periods. These previous proposals have been operable to positively interrupt the fuel supply by means of a shut off valve or equivalent sealing devices. They have not been satisfactory in many cases due to the delay required in recharging the engine when the deceleration period is over or thecomplexity of the machinery involved.

The invention presents a device which shuts off the fuel flow during deceleration by rotating the throttle plate orvalve past the idle jet. When the throttle plate is so rotated, the primary idle discharge passage is upstream of the throttle plate. No vacuum exists at this point and no fuel will therefore flow in the idle circuit. When the deceleration period is over, the throttle valve is returned to the idle position and the accelerator pump will be caused to discharge fuel into the manifold, thus quickly re'-establishing a normal supply of fuel. The idle jet will then be downstream of the throttle valve and the vacuum in that portion of the intake system will cause fuel to flow in the idle circuit. t 9

t In the drawing:

Figure 1 shows a. segment of an intake for an internal combustion engine having a deceleration fuel shut-off mechanism embodying the invention, portions beingbroken away and in section.

Figure 2 shows a cross-section view of the throttle valve controlled by the mechanism of Figure 1,the valve being in position relative to the idle jet.

The internal combustion engine on which the mech anis'm is installed is provided with an intake duct 10 in which a throttle valve 12 is mounted on a rotatable shaft 14. The intake duct preferably has a substantially cir-.

valv'e is in the idle position. A suitable device such as.

This difference indiameters elimi- 2,926,892 Patented Mar. 1, 1960 throttle valve, such as in the intake manifold of the engine. The shaft 14 preferably extends through the walls of duct 10 and beyond either side of the duct. A conventional throttle control arm 26 may be secured to one linkage 56 with accelerator pedal 58. The fuel shut-off mechanism, which is the subject of the invention, may be secured to the other end of the shaft 1 4 or at a point adjacent to the conventional throttle arm on the shaft. fuel shut-off control includes a-cam 24, a throttle control arm 26, an idle speed adjusting screw 28 and a cam control link 30. The throttle control arm 26 is non-rotatably secured to shaft 14 and may be provided with a hole 32 to which the accelerator pump linkage 50 may be attached. Cam control link 30 may be connected to any positioning mechanism which is sensitive to conditions of deceleration in the engine- The vacuum sensitive mechanism 34 is shown by .way of example. Mechanism 34 includes housing 36 forming a vacuum chamber 38 and.

closed at one end by a diaphragm '40. The other side of the diaphragm forms a chamber 42 which may be opened to the atmosphere. A compression spring 44 may be provided in vacuum chamber 38 to resist the vacuum in the chamber and to return cam 24 to its idle position at the end of adeceleration period. The vacuum in chamber 38 is transmitted through line 22 to that cham- An adjustment mechanism may be her from the engine. provided in housing 36 which includes a first screw 46 for adjusting the tension on spring 44 and a second screw engine, cam 24 is rotated to the deceleration position D,

permitting adjusting screw 28 to move toward the center of cam 24. This allowable movement of screw28 permits the rotation of arm 26 and the consequent rotation ofthrottle valve '12 to the deceleration position.

When the deceleration sensing mechanism 34 indicates that the deceleration period is over, the idle return stop cam '24 will be returned to the position I, forcing the .throttle plate 12 back to its position I through movement of adjusting screw 28 and arm 26. Intake vacuum will again be impressed upon the idle discharge jet 16 and the movement of the throttle linkage to the idle position will cause the accelerator pump 52 to discharge fuel through passage 54 into the manifold and re-establish a normal supply of fuel to the engine. This fuel is injected when the manifold vacuum is at approximately the idling-value, thusminirnizing the jerk due to restarting the engine. The throttle valve 12 can be returned to idle position or any other operating position at any time by actuating the conventional throttle mechanism. The fuel shut-off mechanism therefore inno way hinders normal controlof the engine by the vehicle operator.

trol, etc. Since the vacuum in the intake manifold is on the order of 21 to 26 inches of mercury during decel-. 1 eration, while normal idle vacuum doesfnot exceed 21 The nch of memo, th s e e ly igh vacuum ob able only during acceleration provides an excellent control for actuating the deceleration fuel shut-off mechanism. This device will reduce the unburned hydrocarbon during deceleration by cutting off the fuel supply and will aid .in establishing a' smoother engine restartby using the accelerator pump-to aid in re-establishing fuel flow. The time for v reestablishing fuel flow may be shortened to some extent by properly locating the deceleration position of throttle valve 12 relative to idle jetlso that fuelsupply is maintained at a point immediately adjacent the idlejet. By controlling the position of the throttle valve relative to thevidle jet and utilizing the vacuum on the respective sides of the throttle valve, the throttle valve need not be so closelyvfitted to the intake duet thatit must completely seal that duct,

' as has been required by \some fuel supply interrupting systems previously proposed. The difference in duct and throttle valve diameters permits some intake air to flow through the manifold to the cylinders, drying the walls of the manifold quickly and preventing continued fuel combustion over a long period of time after the fuel supply is interrupted.

What is claimed is:

1. A fuel supply control mechanism for an internal combustion'engine, said .mechanism preventing the introduction of fuel into said engine only during zero throttle engine deceleration periods and re.-establishing the supply of said fuel at the end of each of said periods and including an air intake duct having a throttle valve and an idle fuel discharge jet mounted therein, an accelerator pump having means for discharging fuel into saidengine, means sensing said engine zero throttle deceleration periods and operatively connected with and rotating said throttle valve to a first position downstream of said idle jet only during said periods to interrupt fuel flow from said jet, said throttle valve rotating means including biasing means returning said throttle valve to a second position upstream of said jet at the end of each of said periods to re-establish fuel fiow from said jet, and means interconnecting said throttle valve rotating means and said accelerator pump for actuating said accelerator pump upon return of said throttle valve to said second position whereby fuel is discharged into said engine by (said pump.

2. The mechanism of claim 1, said throttle valve rotating means comprising throttle =valve accelerator linkage and'a motor and a cam actuated by said motor and engagingsaid linkage at said first position to permit said throttle valve rotation to said first position under influence of said accelerator linkage and engaging said linkage to return said throttle valve to said second position.

3. Means for preventing the emission of unburned hydrocarbons from an internal combustion engine during zero'tlrottle deceleration periods, said means including a throttle valve and an idle fuel discharge jet and throttle valve control mechanism including a throttle valve zero throttle position limiting cam and means sensing said engine zero throttle deceleration periods and connected with said cam to rotate said cam to first and second positions, an accelerator pedal and linkages connecting .said pedal to said throttle valve-and engageable with said cam, said valve being moved by said linkages relative to .said jet under'control'of said accelerator pedal to be positioned upstream of said jet and limited to the upstream positions by said cam in said cam first position under all operating conditions except zero throttle deceleration and to be positioned downstream of said jet during zero throttle deceleration conditions with said cam in said second position. a

a linkage po i on d lim ting said al e be n mo e able by said linkage to a first position at engine idle relative to said idle jet whereby said jet is downstream of said valve and said valve is limited against movement from said position toward the zero throttle direction by said cam engaging said linkage, and movable by said linkage to a second position and closed throttle deceleration whereby said jet is upstream of saidvalve, said cam having actuating means connecting therewith and including means sensing said engine close'd'throttle deceleration periods for moving said cam out of the first limiting position during said closed throttle deceleration periods.

5. Throttle valve :control mechanism for an internal combustion engine having a throttle valve, said mechanism comprising a shaft supporting'said valve, an arm non-rotatably secured to said shaft for imparting rotary movement thereto and having an idle position adjusting member, a position controlling cam engageable by said member, and means responsive to throttle position and deceleration of the engine and connected with said cam for positioning said cam to limit rotation of said valve in one direction to a predetermined idle position in one cam position and to permit further rotation of said valve in said one direction beyond said predetermined idle position,

during zero throttle deceleration of the engine.

6. The mechanism of claim 5,, said cam positioning means including a motor operatively connected with'the engine air intake and responsive to engine intakevacuurn.

7. Hydrocarbon combustion control mechanism for controlling fuel delivered to aninternal combustion'enginc, said mechanism-including an air intake duct having a rotatable throttle valve mounted therein and an idle fuel discharge jet adjacent said valve, throttle valve control linlo age including an accelerator pedal for moving said throttle valve from engine idle to full throttle, adjustable stop means for said throttle valve operatively connected with said linkage to permit first and'second zero throttle valve positions, engine throttle position and deceleration re- -4. 'Means for'inteiruptingthe fuel supply to an internal combustion engine during closed throttle deceleration periods, said means includinga movable throttle valve and a fuel idle supply jet and linkage actuated by an acce'leratorpedal for controllingmovement of sai'dv-alve 'and sponsive means connected with and controlling said stop means, said valve being rotatable by said linkage to said first position upstream of said jet to idle said engine at zero throttle and to said second position downstream of said jet to interrupt fuel delivered through said jet when the engine is decelerating at zero throttle, said throttle valve having asmaller cross section area than said duet.

8. A fuel supply interruption mechanism for an internal combustion engine, said mechanism comprising a device including a motor connected to the engine intake manifold and responsive only to an intake vacuum greater than that vacuum obtained under normal engine idle conditions and an air intake duct having an idle fuel discharge. jet and a throttle valve therein, said device having a cam interconnected with an'dmovable by said motor and operativcly connected with said throttle valve and limiting movement of said throttle valve to a-predetermined idle position during normal engine idle conditions and moved by said motor and permitting movement'of said valve beyond said idle position when said greater intake vacuum is obtained whereby the fuel supply from said jet to the engine is interrupted.

9. In a fuel supply control mechanism for an internal combustion engine having a throttle valve and an engine air intake controlled by said valve and an engine idle fuel supply jet discharging fuel into said 'airintake and throttle valve control means, limiting cam means engageablerwith said throttle valve control means and adjustable to limit said throttle valve to idle position at zero throttle and to permit additional movement of said throttle, valve beyond idle position at zero throttle to cut off the fuel supply from said idle jet duringzero throttle deceleration of said engine, said limitingcam means including a movable cam engageable by said 'throttlevalve control means and a vacuum energized motor for moving said cam to permit said additional throttle valve movement, said motor including :a return sp i g and having means. interconn c ing turn spring preventing energization of said motor except during engine zero throttle deceleration.

10. Throttle cut-ofi and return mechanism for an internal combustion engine having a throttle valve and an engine air intake with engine vacuum imposed therein downstream of said valve and a fuel supply jet in said intake at said throttle valve and control means for said throttle valve including the valve rotating cam operatively connected with said valve and a cam actuating link and a vacuum motor connected therewith and energizable to rotate said cam through said link in one direction during zero throttle deceleration of said engine and a return spring acting on said cam to rotate said cam in the other direction upon cessation of the zero throttle deceleration condition and a vacuum line connected with said engine intake on said motor and imposing engine vacuum on said motor to oppose said return spring, said engine vacuum energizing said motor to overcome said spring only during 20 zero throttle deceleration of said engine and rotating said throttle valve downstream of said idle jet to cut ofi fuel being delivered therefrom to said engine, said valve remaining upstream of said idle jet during all other engine operating conditions.

11. The mechanism of claim 10 further comprising a fuel pump having means for discharging the fuel therefrom into said engine and linkage operatively connecting said motor and said pump and moved by said motor to actuate said pump upon cessation of said engine zero throttle deceleration condition, said pump then discharging fuel into said engine.

2,036,192 2,665,891 Smitley Jan. 12, 1954 2,762,235

Olson et al. Sept. 11, 1956