Carburetor Emission Control Device

Abstract

The throttle valve of a carburetor is limited in its closing movement by a mechanically and electrically controlled stop, a solenoid connected to the engine ignition circuit is energized upon engine start up to limit closing movement of the throttle valve to a normal idle speed position, engine shutdown permitting closing of the throttle valve by deenergization of the solenoid, subsequent depression of the vehicle accelerator pedal opening the throttle valve and positioning an additional stop means to prevent closing of the throttle valve beyond a fast idle position, for starting purposes.

Description

This invention relates, in general, to means for controlling the movement of the throttle valve of a carburetor. More particularly, it relates to a mechanically and electrically controlled power means to control fuel and air flow through a carburetor to prevent engine dieseling and minimize the passage of unburned hydrocarbons into the atmosphere.

The problem of engine dieseling after the engine has been shut off is recognized. So long as the engine crankshaft continues to rotate, a vacuum signal will be present in the carburetor throttle bore below the throttle valve to pull idle system fuel and air into the hot combustion chamber so that combustion is maintained for a few seconds or longer after the engine ignition is shut off. This naturally is undesirable.

This invention provides a carburetor throttle valve construction that (1) permits closing of the throttle valve upon engine shutdown to reduce fuel and air flow; or (2) is positioned to a curb idle position for normally maintaining the engine at a normal idling speed; or (3) is positioned to a faster idle position for the leaner start of a hot engine.

In the prior art devices, the minimum flow and engine idle speed positions of the throttle valve usually are the same. Therefore, when the engine is shut off, the above conditions exist; that is, the vacuum signal still present for a few seconds draws a sufficient charge of fuel/air mixture into the combustion chamber to maintain the engine running.

The invention provides a construction in which the throttle valve is moved to a closed position upon engine shutdown, to reduce flow to the cylinders and prevent dieseling; is moved to a fast idle position for restarting; and to an engine idle speed position during normal engine operation so that idle system fuel and air flow can be obtained in the conventional manner.

It is one of the objects of the invention, therefore, to provide a carburetor with a throttle valve positioner that will prevent engine dieseling and minimize the passage of unburned hydrocarbons into the exhaust system or atmosphere, and will reposition the throttle valve for a fast idle restart subsequent to engine shutdown.

It is also an object of the invention to provide the throttle valve of a carburetor with a movement that is controlled mechanically and by a solenoid controlled stop to at times permit closing of the throttle valve to reduce flow of fuel and air to the engine cylinders, while at other times positioning the throttle valve to a beyond idle position for a better engine start.

It is a still further object of the invention to provide a carburetor with a multi-position throttle valve actuator mechanically and solenoid controlled, the solenoid being controlled by an electrical circuit including the engine ignition key.

Other objects, features and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawing illustrating a preferred embodiment thereof; wherein;

the FIGURE illustrates schematically a cross-sectional view of a portion of a carburetor embodying the invention.

The FIGURE illustrates a portion 10 of a downdraft type carburetor, although it will be clear as the description proceeds that the invention is equally applicable to other types of carburetors, such as updraft or sidedraft, for example. More particularly, the carburetor is provided with a main body portion 12 having a cylindrical bore 14 containing a conventional venturi (not shown) in an air/fuel induction passage 16. The latter is open at its upper end to air at essentially atmospheric pressure passing through the conventional air cleaner, not shown. At its lower end 20, passage 16 is adapted to be connected to an engine intake manifold, from which the air and fuel mixture passes to the engine cylinders, not shown, in a known manner.

The flow of air and fuel through induction passage 16 is controlled in this instance by a conventional throttle valve 22. The latter is fixedly mounted on a shaft 24 rotatably mounted in the side walls of body 12, in a known manner. A main fuel system is not shown, since it can be any of many known types. The fuel would be inducted into passage 16 above the throttle valve in a known manner as a function of the rotation of the throttle valve from its fully closed position 34 to its wide open nearly vertical position, by the change in vacuum signal.

The carburetor also contains an idle system for supplying the necessary fuel and air to the engine cylinders during engine idling speed operation. A bypass passage 26 contains the usual transfer port 28 and a discharge port 30 controlled by an adjustable needle valve 32.

The transfer port 28 is located in this case so that its lower edge is aligned with the edge of the throttle valve plate in its closed position 34. Alternatively, if desired, the transfer port can be located vertically in other positions relative to the throttle plate edge when in the closed position.

The dotted line position 36 indicates the idle speed position of the throttle valve, while position 37 indicates a fast idle speed or engine hot start position, to be described more fully later.

It will be clear that in the closed position 34, the idle passage area exposed to the vacuum existing below the throttle valve is reduced from that when the throttle valve is in position 36. Therefore, a lower quantity of fuel and air will flow at this time as the area of the transfer port 28 above the throttle valve edge subjects passage 26 to an ambient or atmospheric pressure bleed. The quantity flowable past the needle valve at this time, therefore, is determined to be insufficient to provide the torque necessary to overcome the engine friction.

It will also be seen that when the throttle valve is positioned in its idle speed dotted line position 36, the transfer port area subjected to the vacuum signal below the throttle valve is increased so as to increase the amount of fuel and air to pass through the idle system to the amount needed to maintain the engine at the desired idling speed. It will also be clear that when the throttle valve is moved to position 37, a leaner start of a hot engine will occur. More fuel vapor exists with a hot engine. Therefore, a greater throttle valve opening provides more air flow to produce the desired starting air/fuel ratio.

To accomplish the above, a lever or link 38 is fixed on or formed integral with throttle valve shaft 24 for rotation with it, a tension spring 40 biasing lever 38 in a counterclockwise direction at all times to bias the throttle valve towards its closed position 34.

Lever 38 is adapted to be positioned clockwise to the right, as seen in the FIGURE, to locate the throttle valve clockwise to its normal idle speed position 36, or to the fast engine idle speed position 37, by a solenoid controlled stop 42. The latter includes a solenoid 43 that is adjustably mounted in a bracket 44 secured to the carburetor housing 46, and has an armature 48 movable between the full line position 50 shown and the dotted line position 52, as a function of the operativeness or inoperativeness of the engine.

That is, the operation of the solenoid 43 is adapted to be tied in with the engine ignition system shown schematically as including a line 54 connecting the solenoid through the engine on-off ignition switch 56 to the battery 58 having a ground connection as indicated. Thus, when the ignition key is turned on, for example, an electrical circuit is completed to solenoid 43 to energize the same and move armature 48 to the dotted line position 52. When the ignition system is shut off, for engine shutdown, deenergization of solenoid 43 causes armature 48 to be retracted by a conventional spring, not shown, to the full line position 50 shown.

In this case, the dotted line position 52 of solenoid armature 48 stops the leftward movement of lever 38 at a point corresponding to the desired normal idle speed position 36 of throttle valve 22. The full line position 50 permits the lever 38 to move leftwardly to the fully closed position 34 of the throttle valve.

An additional linkage 60 is provided cooperating with the solenoid armature to control the position of the lever 38 for fast idle start position 37, as well as the normal idle speed position 36. More specifically, linkage 60 includes a finger-like lever 62 hinged to the solenoid case for a pivotal arcuate movement. The lever is bent near its central portion to form a bead-like abutment or cam surface 64 restable by gravity on the armature 50. A conical cam 51 fixed on armature 48 is adapted to engage and cam the lever 62 upwardly to the dotted line position 66 as the armature 48 moves from the full line to the dotted line position upon energization of the solenoid.

The end 68 of lever 62 is adapted, when the armature 48 is retracted as shown, to constitute a stop by engaging lever 38 and preventing further counterclockwise movement than shown. This prevents the throttle valve 22 from closing more than to the fast idle position 37. Vertical swinging movement of lever 62, when armature 48 moves rightwardly, lifts the finger end 68 out of contact with lever 38 and permits the lever to return the throttle valve 22 either to the normal idle speed position 36, or to the closed throttle speed position 34, when armature 48 is retracted.

To summarize briefly before proceeding to the operation, the purpose of the throttle positioner is to provide three positions for emission control; namely, a starting position, in which the throttle valve is opened beyond idle position to provide a leaner start of a hot engine and yet a good start of a colder engine; secondly, a curb idle position against a solenoid armature to which the throttle valve is returned after start and during deceleration operation; and, thirdly, an engine anti-dieseling position in which the solenoid armature is retracted upon engine shutoff to permit full closure of the throttle valve, with a subsequent return to the engine start, fast idle position after a repositioning of the throttle valve by the vehicle operator.

In operation, the parts are shown in the engine-off condition positioned for a fast idle start operation. Prior to the start of the engine, the vehicle operator would depress the accelerator pedal. This will rotate the throttle valve 22 open to or beyond the position 37. With the engine off, solenoid 43 will be deenergized by the open ignition switch 56 breaking the circuit to battery 58. Accordingly, armature 48 will be retracted to the full line position 50 shown, retracting cam 51 leftwardly and permitting lever 62 to drop down onto the armature 48. This positions the finger stop 68 in the path of return movement of lever 38 towards a closed throttle position. Release of the accelerator pedal by the operator, therefore, will permit spring 40 to position lever 38 against stop 68 and position throttle valve 22 in the fast idle speed position 37.

As soon as the engine is cranked, the solenoid armature 48 is moved to the right to the curb idle position indicated at 52. This cams the finger lever 60 upwardly to the dotted line position 66, and permits the throttle return spring 40 now to move lever 38 and the throttle valve to the normal idle speed setting 36. Subsequent depression of the accelerator pedal and release will again return the throttle valve lever against the end of armature 48 to the curb idle speed position 36.

Assuming now the engine is shut off, the solenoid armature 48 immediately will retract to the anti-dieseling position 50. Since the lever 38 is already to the left and under the end 68 of finger lever 62, the lever 38 now can move leftwardly with the solenoid armature to position the throttle valve 22 in the closed throttle setting 34. This reduces the fuel and air flow through the idle system below the level necessary to sustain, running of the engine, and, therefore prevents dieseling.

Claims

We claim:

1. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and beyond normal idle speed mixture flow, and control means to move the throttle valve to and between the positions, the control means comprising a lever fixed to the throttle valve, adjustable stop means operably positionable in the path of movement of the throttle valve in a closing direction to determine the degree of closing of the throttle valve as a function of the operation and inoperation of the engine, the stop means comprising a first member movable to a first stop position in response to engine startup to limit closing movement of the throttle valve to an idle speed position, the first member being movable to a second position in response to engine shutdown permitting movement of the throttle valve to a closed throttle position to prevent engine dieseling, and second means movable at times in response to movement of the first member and movable between first and second positions into and out of, respectively, the path of closing movement of the throttle valve lever, movement of the second means to its first position limiting closing movement of the throttle valve to a fast idle speed position more open than the first aforementioned idle speed position, for engine starting purposes.

2. An engine control as in claim 1, the first member comprising electrically actuated means connected to the engine ignition circuit so as to be responsive to engine operation and inoperation for moving the first member between its second and first positions respectively.

3. An engine control as in claim 1, the first member comprising a solenoid connected to the engine ignition circuit and having an armature movable from the first to second positions as a function of the operativeness or inoperativeness respectively of the engine to either locate the throttle valve at an idle speed position or at a closed throttle position.

4. An engine control as in claim 1, the second means comprising latch means engagable by the first member in response to the movement of the first member from its second to its first position to move the latch means to its second position out of the path of closing movement of the throttle valve lever to thereby permit movement of the throttle valve lever to the idle speed position.

5. An engine control as in claim 4, the movement of the throttle valve lever to the idle speed position rendering the latch means inoperative and permitting further movement of the throttle valve to a closed position in response to engine shutdown moving the first member to its second position.

6. An engine control as in claim 4, the latch means comprising a pivotally mounted finger-like member located in its first position adjacent the first member, and cam means on the first member engagable with the finger-like member to cam it away from the path of closing movement of the throttle valve lever.

7. An engine control as in claim 4, the first member comprising a solenoid moved member connected to the engine ignition circuit so as to be responsive to engine operativeness and inoperativeness to energize or deenergize the solenoid to move the member between its positions, the solenoid moved member having cam means thereon engagable with the latch means.

8. An engine control as in claim 5, the movement of the throttle valve lever to the idle speed position rendering the latch means inoperative and permitting further movement of the throttle valve to a closed position in response to engine shutdown moving the first member to its second position.

9. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and beyond normal idle speed mixture flow, the control means comprising a lever fixed for rotation with the throttle valve, a solenoid connected to the engine ignition circuit so as to be responsive to engine operativeness and inoperativeness to be energized or deenergized respectively, the solenoid having an armature projecting into the path of movement of the throttle valve lever in a throttle valve closing direction to stop the latter movement, the armature having a first deenergized position permitting the throttle valve to close to prevent engine dieseling upon engine shutdown, and a second energized position stopping the movement of the throttle valve at an engine idle speed position, other stop means movable into and out of the path of the throttle valve lever, the other stop means when engaged by the lever preventing closing movement of the throttle valve beyond a fast idle speed position more open than the first mentioned idle speed position, for engine starts, the armature having a cam thereon engagable with the other stop means upon movement of the armature to its energized position to cam the other stop means out of engagability with the throttle valve lever to permit closing movement of the lever to the idle speed and closed throttle position.

10. An engine control as in claim 9, the other stop means being hingedly mounted on the solenoid, and movable by its own weight to abut the armature and in the path of movement of the throttle valve lever.

11. An engine control as in claim 10, the throttle valve lever when moved to the idle speed position blocking return movement of the other stop means to a position in the path of movement of the throttle valve lever, thereby permitting movement of the throttle valve lever to a closed throttle position in response to deenergization of the solenoid.

12. An engine control as in claim 11, the other stop means moving into the path of movement of the throttle valve lever subsequent to engine shutdown in response to movement of the throttle valve lever to the fast idle speed position or beyond to a more open throttle valve position, to condition the throttle valve for an engine start setting upon subsequent release of the throttle valve in the closed throttle valve direction.