US3895615A

US3895615A - Carburetor throttle valve positioner

Info

Publication number: US3895615A
Application number: US422944A
Authority: US
Inventors: Phillip A Schubeck
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1973-12-07
Filing date: 1973-12-07
Publication date: 1975-07-22
Anticipated expiration: 1992-07-22

Abstract

A downdraft type carburetor has a conventional idle system with a transfer port cooperating with the edge of the throttle valve to permit normal idle speed fuel and airflow in one position and a less combustible mixture flow in a second position, as well as a third beyond normal fast idle engine start position; the three positions are controlled by a temperature sensitive vacuum operated servo cooperating with a solenoid operatively engaging the throttle valve; the servo initially positions the throttle valve during engine shutdown to its fast idle position for engine starting, and also permits the throttle valve to move to its most closed position after a running engine has been shut off, to prevent dieseling. The solenoid, when energized during engine operation, permits return of the throttle valve to the normal idle speed position upon release of the vehicle accelerator pedal.

Description

United States Patent [191 Schubeck [451 July 22,1975

1 1 CARBURETOR THROTTLE VALVE 21 Appl. No.: 422,944

[52] U.S. CL... 123/103 R; 123/DIG. 11; 123/179 G [51] Int. Cl. F02D ll/OS [58] Field of Search123/DIG. 11, 198 DC, 198 DB,

123/179 G, 179 R, 103 R, 119 1 ,124 A, 124

Primary ExaminerCharles J. Myhre Assistant ExaminerWilliam C. Anderson Attorney, Agent, or FirmRobert E. McCollum; Keith L. Zerschling [57] ABSTRACT A downdraft type carburetor has a conventional idle system with a transfer port cooperating with the edge of the throttle valve to permit normal idle speed fuel and airflow in one position and a less combustible mixture flow in a second position, as well as a third beyond normal fast idle engine start position; the three positions are controlled by a temperature sensitive vacuum operated servo cooperating with a solenoid operatively engaging the throttle valve; the servo ini- B; 261/165 tially positions the throttle valve during engine shutdown to its fast idle position for engine starting, and [56] References Cited also permits the throttle valve to move to its most UNITED STATES PATENTS closed position after a running engine has been shut off, to prevent diese'ling. The solenoid, when energized 3,730,153 5/1973 Harr son et at. iii/DIG. 11 during engine Operation permits return of the throttle 3760785 9/1973 Harmon at a l valve to the normal idle speed position upon release of the vehicle accelerator pedal.

11 Claims, 4 Drawing Figures '0 P 66 44 c040 START I E 64 la'z &2 l J4 PATENTED JUL 22 ms C040 STIQ QT SHEET FlC-5.2A

C ARBURETOR THROTTLE VALVE POSITION-ER Thisinvention relates, in general, to a device for con- 1 trolling the movement of the throttle valve of acarburetor. More particularly. it relates to a vacuum and it electrically controlled power means to control fuel and airflow through a carburetor to prevent engine dieselthrottle valve upon engine shutdown to reduce thefuel now to the engine to a level not sustaining engine operation; or (2) movement of the throttle valve to a curb idle position for,maintai ning the engine at a normal idling speed; or,( 3) movement of the throttle valve to a fast idle position for the leaner start of a hot engine or richer cold start.

"The invention provides a construction in which a conventional idle system is provided, and the edge of the throttle valve cooperates with a transfer port such 7 that when the throttle valve is moved to itsmost closed position, i'.e., more closed than the normal or curb idle f p ositionfthe idle channel signal is bled to reduce idle system fuel flow below a level that will sustain engine running. I

The invention provides suitable apparatus for moving the throttle valve to its variouspositions to prevent engine dieseling and the emission of unburned hydrocarbons into the exhaust system, while at the same time providing good starting.

It is one of the objects of the inven 'tion, therefore, to provide a carburetor with a throttle valve positioner that will prevent engine dieseling and minimize the passage of unburned hydrocarbonsjand carbon monoxide into the exhaust system or atmosphere, and will reposition the throttle valve for a fast idle restart upon engine shutdown. t M

It is also an object of the inven'tionto provide the throttle valve of a carburetor with a servo that is controlled by-manifold vacuum and a solenoid controlled stop to at times close the throttle valve beyond its normal idle'speed position to reduce the flow of fuel to'the engine cylinders, while at other times positioning the throttle valve to a nor'mal'idle speedposition or to a beyond idle speedposition for a better engine start, asthe case may be. 1

It is a still further object of the invention to provide a carburetor with a mu'lti-position throttle valve servo actuator. the servo being vacuum' a nd solenoid controlled, the solenoid being controlled by an electrical circuit including the engineignition key.

Other objects, features and advantages of the invention will become'moreapparent upon reference to the wherein,

FlG. lshows sfchematically-=a cross-sectional view of.

a portion of a carburetor 'em'bodying the invention; and,

or cold start throttle valve positions,respectively.

.,- :FIG. 1: illustrates .a portion 10 EQf raj-downdraft type carburetor, although it will be .clea a sj thedescription proceeds that the invention is equally.v applicable to otherztypes of carburetors, such as updraft or sidedraft. for example. More partic-ularly the carburetor is pro-. vided with a throttle body portioni1'2 having a cylindrical bore 14 constituting an air/fuel induction passage 16. The passage would contain-ttheconventional venturi, not shown. ,lt is opensat its-upper end 18 to fresh air at essentially atmospheric pressure passing through an air cleaner, also not shown. At .its-lower end 20, passage 16 is adapted to be connected to an engine intake manifold by bolting the flanged portion 21 thereto. The air and fuel mixture then pass to the engine cylinders, not showngin a known manner.

The flow of air and-fuel through induction passage 16 is controlled in this instance by auconventional throttle valve 22.- The latter is fixedly mounted on'ashaft 24 mounted for rotation in the side walls of body 12, in'a known manner. A main fuel system isnot shown, since it can be any of many known types. The fuel would be inducted into passage .16 above thethrottlevalve in a known manner as a function of the rotation of the valve from its closed full line position-shown to a wide open nearly vertical position, by the change inflva'cuum signal. "'z.'. The carburetor also containsa conventional idle system for supplying the necessaryfuel'and air tofthe engine cylinders around the throttle valve during engine idling speed operation. This air and fuelflow is provided throughia bypass passage 26 containing the usual transfer port-27 and an orificed discharge port. 28 controlledby an adjustable needle valve 30. H I

The transfer port 27 is located so that its lower edge is aligned with the edge of the throttlevalve plate in its closed full line position 34. Alternatively, ifdesired, the transfer port can be located verticallyin other positions relative to thethrottle plate edge when/the. latter is in the closed position. The dotted line positions 36- and 37, on the other hand, indicate, respectively, the curb or normal idle speed and fast idle speed, positions ofthe throttle .valve. It will be clear that in the closed position 34, since only the idle passage area of the discharge port 28 is exposed to the vacuum existing below the throttlevalve, the area is less thanwhen the throttle valve is in position 36, for example. A-lower quantity of fuel will flow at this time becauseall of the area of the transfer port 27 above the throttle valve edge subjects passage 26 to an ambient or atmosphericpressure bleed. The idle fuel/air mixture flowable-past the needle valve atthis time, therefore, is selected to be too lean to support combustion.

ltwill also be seen that when the throttle valve is positioned in the curb or normal idle speed dotted line position36, the transfer port area subjected to the vacuum signal below the throttle valve is increased, which will increase the amount of fuel passing through the idle system to an amount neededtolmaintain the engine at-idlingspeedl 'z .r v H Returning nowto therconstructioinfto move the .throt tle.val.ve 22 'betweength ,threefipositions, to ac- .complishthe above, a lever or ink,38 isjfixed on or 3 formed integral with throttle valve shaft'24 for rotation with it. A tension spring 40lbiases lever 38 in a counterclockwise direction at all'tinies to bias the throttle valve to the closed position 34 j Lever 38 is adapted to be moved clockwise to the right to rotate throttle valve 22'clockwise to the normal idle speed position 36, or to the fast engine idle speed position 37, by a servo device As best seen in FIGS. 2a, 2b and 2c, the latter includes a sleeve type housing 44 open at both ends, The sleeve is spot welded to a mounting bracket 46 which is .bolted or otherwise secured to the carburetor throttle flange 21.

Sleeve 44 has a larger diameter bore portion 50 that slidably accommodates the housing 52 of a'solenoid 54. The solenoid housing is stopped in one direction of movement by the shoulder 56 separating the bores. The solenoid is of a known construction. It has a plunger 58 extendingthrough the housing, with a button element 7 60 at one end and a magnetic disc 62 at the opposite end. The end 60 is adapted to be engaged with the throttle valve lever 38 at all times. The throttle valve return spring 40 normally biases the lever 38 and plunger to the closed full line position shown in FIG. 1.

The left end of sleeve 44 is cut away for approximately one-half of its circumference, as indicated at 64 in FIG. 1, for assembly purposes, and is formed with an open end yoke 66. Received within the yoke is a temperature sensitive vacuum actuated servo 68. It has an outer shell 70 divided into three

chambers

72, 74 and 76 by two annular

flexible diaphragms

78 and 80. The outer chamber 72 is a vacuum chamber. It is connected by a tube 82 containing an orifice 83 to an engine intake manifold port. While not shown, it would be located below the closed position of the throttle valve 22. 'A spring 85 normally biases diaphragm 78 to the right.

The other outer chamber 76 is an air chamber vented through the clearance space 86 in the end of the shell The center chamber 74 is further subdivided into two

parts

87 and 88 by a partition 89. The partition hasa pair of

flow openings

90 and 92. 90 is a fixed area flow passage or orifice, with a one-way flap type check valve 94 covering one end. 92 is a smaller variable area orithrough the orifice 92 at a controlled rate causing the shaft or plunger 98 to retract or move to the left. The rate of retraction will depend upon the viscosity of the fluid 100, which will vary as a function of the temperature, i.e., low temperature, high viscosity. Thus, the servo will constitute a vacuum controlled dashpot. When vacuum is removed, such as when the engine is shut down, the spring 85 will force the fluid to open check valve 94 and more quickly extend the plunger 98 to the right.

In operation, the parts are shown in FIG. 2c in the engine cold start-position. No vacuum is applied to servo 68, so plunger 98 is extended by spring 85 a maximum to the right. This pushes disc 62 attached to the solenoid armature 58 to the right, as well as the solenoid housing 52 away from shoulder 56. The solenoid is deenergized, and so disc 62 can move freely. The lever 38 then is positioned such as to position the throttle valve. for a fast idle speed start position 37. More fuel vapor exists with a hot engine. Therefore, a greater throttle valve opening provides more airflow to produce the desired starting air/fuel ratio. This also provides the richer start of a cold engine.

The operation of the solenoid 54 per se is adapted to be tied in with the engine ignition system, not shown, so that when the ignition key is turned on, for example. an electrical connection is made to solenoid 54 through wiring harness 102 to energize the same and maintain disc 62 in the position shown in FIGS. 2b and 20. When the ignition system is shut off, for engine shutdown. deenergization of solenoid 54 permits plunger 58 and disc 62 to be moved by the lever 38 to the position shown in FIG. 2a, which will be described.

The above described ignition connected circuit could be similar to that shown and fully described in U.S. Pat. No. 3,682,148, Carburetor Throttle Valve Positioner, Robert S. Harrison and Max W. Lunsford. It could include, for example, a known type of ignition key operated switch bridging or breaking the circuit from a battery to the coil of solenoid 54.

When the engine is started, solenoid 54 is energized and disc 62 is attracted to housing 52. Vacuum applied through tube 82 slowly pulls or retracts plunger 98 to the left as a function of the rate of bleed of fluid from.

the right side 88 of partition 89 to the left side 87 through the orifice 92. This continues until the plunger 98 reaches the position shown in FIG. 2. Simultaneously, the throttle valve return spring 40 shown in FIG. 1 causes the throttle valve to follow the servo plunger movement, moving the armature 58 and solenoid housing 52 as a unit to the left until the housing is stopped by shoulder 56. The throttle valve is then located at the dotted line position 36, or the curb idle speed position. The throttle valve will then always return to the position shown in FIG. 2b, so long as the engine is running.

Assume now that the engine is shut off. The solenoid now is de-energized, which permits'the throttle return spring 40 through lever 38 to push plunger 58 to the left and move the disc 62 up against the end of plunger 98 This positions the throttle valve in the anti-dieselin g closed position 34 shown in FIG. 2a. The vacuum is also removed from chamber 72. However, since the vacuum is applied through the orifice 83, vacuum will remain in chamber 72 for a few seconds after engine shut-off. This, coupled with the necessity of the fluid in servo 68 having to pass through the two orifices and 92 to extend the plunger 98, is sufficient time to decay the idle channel signal in passage 26 to a value below the air/fuel mixture level that is necessary to sustain engine operation. After the time delay, the plunger 98 will then slowly move to the right to reposition the solenoid housing 52 and plunger 58 again to the restart position 37 shown in FIG. 20.

Therefore, it will be seen that the invention provides a throttle valve positioner which during normal engine operation permits a normal engine idle speed position; 1

reduces the idle system fuel flow and prevents engine dieseling after the engine is shut off, for a period of time sufficient to permit the engine to come to rest; and

subsequently repositions the throttle valve to an attitude providing engine starting.

While the invention has been shown and described in its preferred embodiment, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.

1 claim:

1. A carburetor throttle valve positioner 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 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, and control means to move the throttle valve to and between the positions,

the control means including a first engine vacuum responsive device having first means operatively acta ,ing on and biasing the throttle valve to a first open beyond normal engine idle throttle position, engine vacuum acting on the first means moving the first means to a position permitting return movement of the throttle valve to a closed position during operation of said engine, second movable stop means movable from an initial engine off position positioning the throttle valve in the first position to a second position during operation of the engine to prevent return movement of the throttle valve to a position less open than the normal idle speed position, and means effecting movement of the second means to a third position immediately upon engine shutdown to permit movement of the throttle valve to a closed anti-dieseling position reducing the flow of fuel to the engine.

2. A positioner as in claim 1, the vacuum responsive device being rendered operable and inoperable in response to temperature changes from a predetermined level.

3. A positioner as in claim 1, the vacuum responsive device including a movable plunger operatively extendable into the path of movement of the throttle valve, and a temperature responsive dashpot connected to the plunger to control the rate of movement of the plunger.

4. A positioner as in claim 1, including a solenoid connected to the second stop means and energizable upon engine start-up to move the second stop means to the second position operatively preventing closing of the throttle valve beyond normal idle speed position, and movable in response to engine shutdown deenergizing the solenoid to the third position permitting closure of the throttle valve.

5. A positioner as in claim 4, the solenoid being movable to define a joint movement at times with the second stop means, and further means to stop the movement of the solenoid in one direction.

6. A positioner as in claim 1, the device including time delay means to delay the movement of the said second means.

7. A positioner as in claim 6, the time delay means being responsive to temperature changes to vary the delay rate.

8. A throttle valve positioner as in claim 1, the first device comprising a vacuum responsive servo having a first plunger, the first means comprising a spring biasing the first plunger in a throttle valve opening direction and at times against a second plunger constituting the second stop means, a solenoid connected to the second plunger for moving the same in a throttle valve closi'ri'g direction when energized and when deenergized permitting free movement in either direction of the plunger by an operative connection to the throttle'valve, and means mounting the solenoid for free movement in a throttle valve opening direction and for movement against a third stop in the throttle valve closing direction thereby permitting and effecting the movement of the second stop means to its one and secondpositions.

9. A positioner as in claim 8, the servo including temperature responsive time delay means controlling the rate of movement of the first plunger as a function of temperature changes from a predetermined level.

10. A positioner as in claim 1, including conduit means connecting manifold vacuum to the first device,

and flow restriction means in the conduit means whereby decay of vacuum level at engine shutdown is delayed so that the second stop means and throttle valvefinitially move to close the throttle valve upon shutdown of the engine, to reduce engine dieseling fuel flow; and subsequently are moved by the first means to an engine start open beyond normal idle throttle valve first position upon decay of the vacuum level.

11; A positioner as in claim 8, including conduit means connecting manifold vacuum to the first device, and flow restriction means in the conduit means whereby decay of vacuum level at engine shutdown is delayed so that the second stop means and throttle valveiinitially move to close the throttle valve upon shutdown of the engine, to reduce anti-dieseling fuel flow, and subsequently are moved by the first means to the engine start open beyond normal idle throttle valve first position upon decay of the vacuum level.

Claims

1. A carburetor throttle valve positioner 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 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, and control means to move the throttle valve to and between the positions, the control means including a first engine vacuum responsive device having first means operatively acting on and biasing the throttle valve to a first open beyond normal engine idle throttle position, engine vacuum acting on the first means moving the first means to a position permitting return movement of the throttle valve to a closed position during operation of said engine, second movable stop means movable from an initial engine off position positioning the throttle valve in the first position to a second position during operation of the engine to prevent return movement of the throttle valve to a position less open than the normal idle speed position, and means effecting movement of the second means to a third position immediately upon engine shutdown to permit movement of the throttle valve to a closed anti-dieseling position reducing the flow of fuel to the engine.

4. A positioner as in claim 1, including a solenoid connected to the second stop means and energizable upon engine start-up to move the second stop means to the second position operatively preventing closing of the throttle valve beyond normal idle speed position, and movable in response to engine shutdown de-energizing the solenoid to the third position permitting closure of the throttle valve.

8. A throttle valve positioner as in claim 1, the first device comprising a vacuum responsive servo having a first plunger, the first means comprising a spring biasing the first plunger in a throttle valve opening direction and at times against a second plunger constituting the second stop means, a solenoid connected to the second plunger for moving the same in a throttle valve closing direction when energized and when de-energized permitting free movement in either direction of the plunger by an operative connection to the throttle valve, and means mounting the solenoid for free movement in a throttle valve opening direction and for movement against a third stop in the throttle valve closing direction thereby permitting and effecting the movement of the second stop means to its one and second positions.

10. A positioner as in claim 1, including conduit means connecting manifold vacuum to the first device, and flow restriction means in the conduit means whereby decay of vacuum level at engine shutdown is delayed so that the second stop means and throttle valve initially move to close the throttle valve upon shutdown of the engine, to reduce engine dieseling fuel flow, and subsequently are moved by the first means to an engine start open beyond normal idle throttle valve first position upon decay of the vacuum level.

11. A positioner as in claim 8, including conduit means connectIng manifold vacuum to the first device, and flow restriction means in the conduit means whereby decay of vacuum level at engine shutdown is delayed so that the second stop means and throttle valve initially move to close the throttle valve upon shutdown of the engine, to reduce anti-dieseling fuel flow, and subsequently are moved by the first means to the engine start open beyond normal idle throttle valve first position upon decay of the vacuum level.