US2957463A

US2957463A - Fuel cut-off for carburetor equipped engine

Info

Publication number: US2957463A
Application number: US616971A
Authority: US
Inventors: Julius W Schnabel
Original assignee: Thompson Ramo Wooldridge Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1956-10-19
Filing date: 1956-10-19
Publication date: 1960-10-25
Anticipated expiration: 1977-10-25

Description

Oct. 25, 1960 J, w, SCHNABEL 2,957,463

FUEL CUT-OFF Foa CARBURETOR EQUIPPED ENGINE Filed oct. 19, 1956 z snaps-sheet 1 anw Amm/ma Oct. 25, 1960 J, w, SCHNABEL 2,957,463

FUEL CUT-OFF FOR CARBURETOR EQUIPPED ENGINE 2 Sheets-Sheet 2 United States Patent FUEL CUT-OFF FOR CARBURETOR EQUIPPED ENGINE Julius W. Schnabel, Euclid, Ohio, assignor to Thompson Ramo Wooldridge Inc., a corporation of Ohio Filed oct. 19, 1956, ser. Nb. `616,911

6 claims. cci. 12s- 97) The present invention relates to improvements in fuel 'flow control systems for engines 'and more `particularly l to an improved system for preventing the undesirable effects of deceleration in an internal combustion engine, such as the overow of the carburetor float chamber and the supply of unnecessary fuel to the engine. j

In operation of an internal combustion engine, the l the fuel ow system to obtain improper combustion.

The vacuum in the manifold will greatly exceed the vacfuum at idle speed when thethrottle is released and the engine is still being turned over at high speeds through 'the' transmission. As a result, the sonic velocity of air passing through the throttle plate is attained. In the conventional carburetor this will result in an excessive 'amount of fuel being drawn through the idling system.

This will produce an over-rich mixture and an excess of fuel which is not completely burned by the engine. 'This fuel is unnecessary in that no power is required by the engine when it is to be decelerated. This condition also results in a waste of fuel and the production of un- Aburned hydrocarbons which exude from the exhaust tail pipe in the form of obnoxious exhaust fumes. These fumes indicate a waste of fuel as well as contributing to smog in areas which are heavily populated with automobiles.

The present invention contemplates minimizing the discharge of unburned hydrocarbons during deceleration and eliminating the waste of fuel by cutting oif the 'fuel supply during the deceleration period. The fuel cut-off is accomplished by bleeding air into the idle sys- `tem, which prevents the fuel from being drawn into the engine due to the vacuum in the intake manifold. The cut oif of fuel during deceleration is also'additionallfy and independently accomplished by a shut off of fuel before it enters the float chamber. During deceleration the engine vibration will frequently cause the float needle valve to unseat and fuel to enter the float chamber, and lthis may cause a ooding of the iioat chamber to a point vwhere the fuel is dumped into the intake manifold through the carburetor main jets. Fuel is prevented ,from being drawn in through the idling jets and the liow of fuel to the oat chamber is prevented during deceleration. Thus, the two systems mutually contribute to automatically prevent unnecessary use of fuel during defceleration and avoid the accompanying -undesirable effects.. t `It is, therefore, an object of the invention to lprovide vairatltomatic .system which will prevent -theundesirable 'linkage by an acceleration member 12,

Patented Oct. 25, 1960 y ice effects of the burning of unnecessary fuel during deceleration of an internal combustion engine.

Another object of the invention is to provide an automatic system which will shut off the ow of fuel from the fuel supply to the fuel consumption system of an engine during deceleration.

A further object of the invention is to provide an automatic system which will terminate the supply of fuel to the carburetor iioatY chamber during deceleration.

A still further object of the invention is to provide a method and apparatus for preventing the continued supply of unnecessary fuel to an engine during deceleration through the idling jets of a carburetor by bleeding fair through"'openings in the idling jets.

'A still further object of the invention is to provide "a'sys'tem which'will'terminate the supply of fuel to the fuel consumption system of an engine during deceleration in response to increased intake manifold vacuum.

Another object of the invention is to provide a system which Will terminate the supply of fuel to a fuel consumption system of an engine during deceleration during the time ythe engine is operating at high speeds -and will automatically initiate the flow of idling fuel to the engine when it decelerates to an idling speed.

Another object of the invention is to automatically prevent the supply of fuel to the fuel consumption sys- -tem of an engine during deceleration in response to increased vacuum in the intake manifold and sustained :engine speed, but will automatically supply fuel to the 'engine when the throttle operating accelerator member is'moved' away from the deceleration position.

Other objects and advantages will become more apparent throughout the teaching of the principles of the `invention with the disclosure of the preferred embodiments thereof in the specification, claims and drawings in which:

Figure 1 is a diagrammatic illustration of the fuel ow control system of the preferred embodiment;

`advantage of the various aspects of the invention.

In the preferred embodiment, as illustrated in Figure `l, a carburetor is shown diagramrnaticalll at 4. The

carburetor has the air flow passageway 6 through which a down draft of air ilows as controlled by the butterfly throttle Valve 8. This throttle valve is mounted on a pivotal support 10 and is suitably controlled through If the arrangement is used in an automobile, for example, the accelera- .tion member 12 will be the foot pedal available to the `driver and` operation of the foot pedal will control the speed of the engine through the manipulation of the throttle valve in the manner which is well known to the art.

As illustrated, the acceleration member 12 connects vby a link 14 to a bell crank member 16, which is pivoted at `18 on a fixed support 20. One arm'of the bell crank member is connected to the link 14 to the acceleration member 12, and the other arm is connected to a link 22, which leads to the throttle valve 8. The acceleration link 22 also operates a control switch in a manner which later will be described. v A

The idling jet of the carburetor is shown generally at 24. The -jet opening-is illustrated Vat 26 with an adjustable needle valve 28 in the opening. This needle valve regulates the flow of fuel from a passageway 30 through the opening 26 to be fed into the air stream moving downwardly through the passageway 6 in the carburetor. As is well known in the art, when the throttle valve 8 is moved to the closed position where it is across the passageway 6, as shown in Figure 1, the increased vacuum in the carburetor, which connects to the intake manifold, draws idling vfuel through the orifice 26 of the idling jet 24.

The idling needle is provided with a longitudinal bored passageway 32, which meets a transverse passageway 34 in communication with the orifice `26A of the jet. When the passageway 32 and the lateral passageway 34 are vented to atmospheric air, the carburetor will not draw fuel in through the orifice 26, but will draw air from the outside atmosphere. To vent the idling jet 24, a control valve 36 is provided controlling the flow of air through an atmospheric passageway 38. The valve 36 may be of the normal poppet type having an orifice 40 with a movable poppet 48, which is electrically operated by a solenoid 50. This solenoid is operated through an electrical circuit 52, which will be operated in a manner later described.

It has been found that the placement of a small vent opening 4, leading into the atmospheric passageway 38, will improve the operation of the idling valve 24 during normal operation when the poppet valve 36 is closed. Also it has been found that the placement of a small vent opening 54, leading into the atmospheric passageway 38, will prevent fuel from being trapped lin passageway 38 by keeping said passageway at an atmospheric pressure level at all times. If this vent is not provided, passageway 38 could attain subatmospheric conditions which will cause fuel to flow in said passageway.

During deceleration of the engine, when it is driven by the wheels of a car, if employed in an automobile, vibration occurs, vibrating the float-controlled needle valve that is usually employed to control fuel level in a carbu retor float chamber. This will frequently cause the oat chamber to overflow, and this condition will be aggravated by the fact that no gasoline is being withdrawn from the carburetor due to the deactuating of the idling jet '24. Ovenflow of the carburetor float chamber is undesirable and flooding of the chamber may dump fuel into the intake manifold through the carburetor main jets, thereby defeating the purpose of the fuel cut-off at the idling jets. To avoid these undesirable effects, a float chamber control valve 56 is provided. This valve controls the flow through the passageway 58, which leads to the carburetor oat chamber and which receives fuel from the passageway 60 leading from the fuel pump. The drawings illustrate the use of a lter 62 between the fuel pump and the carburetor flat chamber, although this is not essential to the operation of the mechanism.

The control valve 56 is of a conventional type, and as illustrated, utilizes an orifice 64 with a poppet 66 movable therein between open and closed position. The poppet is carried on a plunger 68 movable within the coil of the solenoid 70. This solenoid is operated through an electrical circuit 72 which is supplied electricity in a manner which will later be described, from the same source that supplies the valve 36 for the idling jet.

While the control systems of Figures 1, 2 and 3 vary, they operate the fuel consumption system of theV engine in the same manner as the embodiment of Figure l utilizing a valve 36 for controlling bleed air to the idling jet, and utilizing a fuel valve 58 for shutting off the flow of fuel to the carburetor float chamber. Therefore, like numbers are used for like parts in Figures 1, 2 and 3 and cross-reference may be made between the similar elements of these figures. It will be understood, however, that elements of the control system could be arranged in various. combinations with fuel tlow control valves, and

the automatic control system could be used with individua1 valves such as 36, the air bleed valve for the idle jet, or float control valve 56 for the fuel fed to the carburetor oat chamber.

The operation of

valves

36 and 56 is dependent on the position of the accelerator member 12, the speed of the engine (as manifested by the output of the generator 74), and the intake manifold pressure (as sensed by the pressure switch operating member 76). Each of these three elements must furnish the proper signal to the system or the valves will not be operated.

The circuits represented by the electrical lines 52 and 72 are supplied by a line 78, which is supplied electricity through a valve control switch 80. Electricity is supplied for the circuits from a suitable source such as a battery 82, which is capable of furnishing a continuing supply of current.

The valve control switch 80 is operated by an electrically operated motive means such as a switch operating solenoid 84. The solenoid is supplied with electricity through two circuits. The solenoid is first energized by electricity flowing through the operating circuit 86 and is then maintained in an energized condition by electricity flowing through the holding circuit 88. The holding circuit is maintained in a closed condition by the holding switch 90, which is also mounted on the movable core 92 of the solenoid which operates the valve control switch 80.

The electricity is supplied to the solenoid 84 through both circuits from the generator 74, which, of course, produces electrical energy in proportion to its speed. This generator serves as a means responsive to the speed of the engine and will have an output of electrical energy that is sufficient to energize the solenoid 84 during operating speeds of the engine, but when the engine drops to idling speed, its output will be insufficient to maintain the solenoid 84 in energized condition. Thus, only when the engine is operating at other than idling speeds, will the solenoid be energized to operate the valve control switch to in turn operate the fuel control valves 36 and 5 6 to terminate the supply of fuel to the fuel consumption system of the engine.

The second condition which must be present to operate the solenoid 84 to thereby operate the fuel flow terminating valves, is that the acceleration member 12 must be in the deceleration position. As shown in the illustration, the acceleration member 12 may be the ordinary foot pedal of an automobile which, when the foot pressure is released, will be moved into deceleration position by a return spring 94. When in the decelerated position, the link 22 will position the movable switch arm 96 against the stationa-ry contact 98 to close the switch 100 thereby completing the circuit from the generator 74 to the solenoid 84 via the pressure responsive switch 102.

The pressure responsive switch has a movable arm y104 which moves against the fixed contact 106 when the operating rod 108 is moved downwardly. This rod is connected to a diaphragm 110 of the pressure responsive member 76. This has a conduit 112 which connects to the intake manifold of the engine. When the vacuum of the intake becomes sufficiently high, the diaphragm 110 is drawn downwardly against the spring 114 to close the switch 102. This completes the circuit 86 to the solenoid 84, causing it to be energized. Energization of the solenoid closes the contacts of the holding switch 90. Thus, once the solenoid has been energized, the decreasing vacuum of the intake manifold due to the engine slowing to idling speed will permit the pressure responsive switch 102 to open but this will not deenergize the solenoid, which remains energized through the holding switch 90.

As the engine begins to first slow down, due to the acceleration member 12 being moved to the decelerated position, the supply of idling fuel to the idling orifice 26 will be cut of since the poppet 48 will be moved away from the orifice 40 bleeding air through the idling jet needle 28. The flow of fuel through the carburetor iioat chamber will also be terminated by the closure of the poppet 66 against the orifice 64.

This condition of the

valves

36 and 56 will continue until the engine slows to a speed whereby the output of generator 74 is insufficient to maintain the solenoid 84 energized; until the acceleration member 12 is again moved to an accelerated position whereupon switch 100 is opened; or until the wiring breaks or the circuit fails to permit

values

56 and 36 to assume their normal position when the solenoids 50 and 7 0` are not energized.

In the iirst condition, the engine will normally slow down with the acceleration member 12 released, until the output from the generator is reduced. This will permit contacts of switch 80 to open breaking the circuit to the valve control solenoids 50 and 70, whereby valve 36 will close and idling fuel will be fed through the idling jet 24 in the normal manner. Valve 56 to the carburetor float chamber will open to resume the normal supply of fuel.

Also, if the acceleration member is pushed down, switch 100 will open thereby deenergizing the solenoid 84 and causing a deenergization of the two valve operating solenoids 50 and 70.

The other condition which may occur is the failure of the circuit due to breaking of the leads or electrical failure of the battery 82 or the like, and this operates as a fail-safe arrangement to cause the system to permit the engine to operate in the manner heretofore known to the art.

In the embodiment of Figure 2, the circuits 52 and 72 are supplied by a line 116, which is controlled by switch 118 leading to the battery 120. This valve operating switch 118 is connected to the plunger 122 of a solenoid 124. The solenoid is energized through a switch 126. The switch 126 is controlled in position by the acceleration member 128. The acceleration member connects to a bell crank 130 by a link 123 with the bell crank operating switch 126 through a linkage 134. When the accelerating member is released, the switch 126 closes, completing the circuit from the generator 136 to energize the solenoid |124. This, of course, causes operation of the valve operating solenoids 50 and 70 and the flow of fuel to the fuel consumption system in the engine will be terminated. This condition will continue until the speed of the engine is reduced to a point where the output of the generator 136 is insutiicient to maintain the solenoid 124 in energized condition, or until the accelerating member 128 is again pushed down to an accelerated position.

In the embodiment of Figure 3, the circuits 52 and 72 for supplying the valve operating solenoids 50 and 70 are connected to a line 138. This line is supplied electricity from the battery 140 and through a switch 142. The switchv 142 is controlled by pressure responsive member 144, which is suitably connected as by conduit 146 to the intake manifold in the engine. When the engine is slowed own by positioning the throttle in the decelerating position, the intake manifold vacuum will increase and the diaphragm 148 of member |144 will draw downwardly on the plunger 150 against the spring 152 to close the switch 142. This will complete the circuit through the valveoperating solenoids 50 and 70 to open the air bleed valve 36 and to close the fuel control valve 56. These valves will again automatically be released when the manifold pressure increases to a predetermined value to open the control switch 142.

Although the operation of the overall mechanism will be apparent from the foregoing description of the various elements and their relationship to the mechanism as a whole, a summary of operation will be helpful in understanding the achievements and objectives of the invention.

In the operation of the engine, the throttle valve 8 is turned to the closed position when the accelerator member 12 is released. Releasing the accelerator member 12 closes the switch 100 to complete the circuit to energize the solenoid 84 through switch 102. Switch 102 is closed duetothe vacuum in the intake chamber which operates the pressure sensing member 76. Electricity is generated by the generator 74 to energize solenoid 84. Energization of solenoid 84 draws down the plunger 92 to close the holding switch and to also close the valve control switch 80.

Closure of the valve control switch energizes the valve operating solenoids 50 and 70. Solenoid 50 opens valve 36 to bleed air through the passageways 32 and 34 of the adjustable needle 28 of the idling jet. This feeds air through the orifice 26 rather than fuel and terminates the flow of idling fuel into the carburetor. Solenoid 70 closes the valve 56, thus terminaling the ow of fuel to the carburetor float chamber preventing it from overflowing due to vibration of its float controlled needle valve. This prevents overow of the carburetor and possible feeding of fuel through the main carburetor jets.

Thus, it will be seen that I have provided an improved fuel flow control system which meets the objectives and advantages hereinbcfore set forth. The system reliably terminates the iiow of unwanted fuel to the engine fuel consumption system during deceleration of the engine. Simultaneously, the system also terminates the flow of fuel to the carburetor float chamber and prevents the feeding of any fuel through the main jets and prevents the overiiow of the iioat chamber. Normal operation is again assumed when the speed of the engine drops to a point where the output of the generator is insufficient to maintain the operation of the valves. Upon the occurrence of these events or the movement of the'throttle control from the decelerated position, the engine will again operate in its normal condition. The system is reliable and may be utilized on existing engines or provided in new designs.

I have, in the drawings and specification, presented a detailed disclosure of the preferred embodiments of my invention, but it is to be understood that I do not intend to limit the invention to the specific forms disclosed, but intend to cover all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by my invention.

I claim as my invention:

l. vA fuel system for regulating the flow of fuel from a supply to a fuel consumption system for an engine including a carburetor having a throttle valve, the system comprising an electrically operated idling valve for the carburetor, an electrically operated valve to control the ow of fuel to the carburetor float chamber, a control switch in the circuit to said electrically operated valves, a solenoid for operating said control switch, a holding switch controlling an electrical holding circuit to operate the solenoid, a solenoid operating circuit separate from the holding 'switch circuit, a generator adapted for connection to the engine and generating power for both the hold ing switch circuit for the solenoid and the operating circuit therefor, anA acceleration memberv adapted for connection tothe carburetor to move the carburetor throttle valve between an acceleration and a deceleration position, a switch connected to the acceleration member and controlling the holding switch circuit and the operating circuit and moved to closed position when the acceleration member is moved to deceleration position, and a vacuum operated switch adapted for connection to the intake manifold of the engine and closing the operating circuit to the solenoid whereby the operating circuit is completed when there is sufficient vacuum in the intake manifold, the solenoid remaining operative through the holding switch to close the valve control switch and operate the valves to terminate the supply of fuel to the engine until the electrical supply is terminated by the generator losing speed or the acceleration member moved to accelerated position.

2. A fuel system for regulating the flow of fuel from a supply to a fuel consumption system for an engine including a carburetor having a throttle valve, the system comprising a manually controlled acceleration means for operating the throttle valve of the carburetor, speed responsive means adapted for connection to the engine and responsive to the speed of the engine, pressure responsive means adapted for connection to the intake manifold of the engine andY responsive to intake pressure, a valve operatively connected to control the fuel ow from the supply to the engine fuel consumption system, and a valve operating element for said valve controlled by the acceleration means being moved to deceleration position, by the speed responsive means when the engine is operating above a predetermined speed, and by the pressure responsive means at a predetermined vacuum whereby the valve is operated to terminate the flow of fuel to the engine only when the valve operating element is controlled by all of said means.

3. A fuel system for regulating the How of fuel from a supply to a fuel consumption system for an engine including a carburetor having a throttle valve comprising a manually controlled acceleration means for operating the throttle valve of the carburetor, a generator means adapted for connection to the engine to develop electrical energy in accordance with the speed of the engine, pressure responsive means adapted lfor connection to `the intake manifold of the engine and responsive to intake pressure, a valve operatively connected to control the fuel flow from the supply to the engine fuel consumption system, and means connecting the acceleration means, the generator means, and the pressure responsive means to the valve whereby the valve is operated only when the acceleration means is moved to a decelerated position, when the engine is operating above a predetermined speed so that the output of the generator means is above the predetermined limit, and when a predetermined vacuum is present in the intake manifold whereby the ow of fuel to the engine is terminated only when all conditions are present.

4. A fuel system for regulating .the flow of fuel from the supply to a fuel consumption system @for an engine iincluding a carburetor having la throttle valve, the system comprising `a valve operatively connected to control the ow of fuel from the supply to the engine fuel consumption system, yan' electrical operating circuit 'for said valve, a valve control switch in said circuit, an electrical switch operator `adapted to operate vthe valve control switch, an operating circuit .for said electrical switch operator, a vacuum controlled switch in said operating circuit `adapted to be connected to .the intake manifold of the engine and close the circuit at a predetermined engine vacuum, a holding circuit for said electrical switch operator, a holding circuit switch operatively connected `to .the `electrical switch operator and adapted to be closed when the operator closes the valve control switch, an acceleration member connected to the throttle valve and movable between an lacceleration and :a deceleration position, and a switch connected to the accelerator and electrically connected to energize the holding circuit and the operating circuit when the acceleration member 'is moved to deceleration position, the holding circuit maintaining .the switch operator energized and maintaining the valve control switch closed regardless ofthe opening of the -vacuum switch.

5. A fuel ysystem for regulating the flow of fuel from a supply to a fuel consumption system for an engine including `an intake manifold :and a carburetor with a throttle valve, the system comprising a fuel flow control valve positioned .to control the flow of fuel to the fuel consumption system, means for operating said fuel flow control valve, pressure responsive means connected to send an operating signal to the valve operating means when the vacuum in the intake manifold is at a predetermined level, an acceleration member connected to the throttle valve of the carburetor and sending :an operating signal to the valve operating means when moved to a deceleration position, said valve operating means being operative only when a signal is received from both .the acceleration member and the pressure responsive means, and means for continuing operation .of the valve operating means when the pressure responsive means terminates its operating signal and continuing operation of fthe valve operating means until the acceleration member is again moved to an acceleration position.

6. A fuel system for regulating the ow of fuel from a supply to a fuel consumption system for an engine including a carburetor comprising a fuel flow valve positioned to control the W of lfuel from the supply to .the fuel consumption system, means for operating the valve, pressure responsive means adapted for connection to .the engine intake manifold and furnishing avsignal to the valve operating means at a predetermined minimum pressure, speed responsive means adapted for connection to the engine and supplying a signal to fthe valve operating means when operating above a predetermined speed, an acceleration member furnshing asignal to the valve operating means when moved to a deceleration position, said valve operating means operative only when receiving each of said signals, and means terminating the operation of .the valve operating means to open the valve when the speed of the engine drops below a predetermined level or when the .acceleration member is moved to an acceleration position but preventing ltermination of operation of the operating member when the pressure `in the manifold increases above said predetermined pressure.

References Cited in the le of this patent UNITED STATES PATENTS 1,461,662 Kawamura July l0, 1923 1,982,049 Fageol Nov. 27, 1934 2,674,443 Bracke Apr. 6, 1954 2,724,375 Schaffer Nov. 22, 1955 2,733,696 Schneider Feb. 7, 1956 2,749,894 Sariti et al. June l2, 1956 2,764,962 Warren et al. Oct. 2, 1956