US2086023A - Automatic carburetor choke control - Google Patents

Description

July 6, 1937. J. w. r-'rrz GERALD 286,023

AUTOMATIC CRBURETOR CHOKE CONTROL l A Filed Dec. 8, 1934 f@ 4- L72757347 MIE/25575@ /Ww Patented July 6, 1937 p UNITED STATES PATENT OFFICE AUTOMATIC CARBURETOR CHOKE CONTROL Application December 8, 1934, Serial No. 756,629.

15 claims. (01.123-119) This invention relates to improvements in automatic controls for carburetor choke valves and and has an object to provide novel means for both `closing and eiecting the re-opening of a choke valve in response to differential in fluid pressure created by the engine.

More speciiically it is an object of this invention to provide a control for choke valves which is actuated to close the valve by engine suction or other fluid pressure prevalent during the cranking of the engine and operable in response to an increase in the same fluid pressure as the engine starts to operate under its own power for effecting the opening of the choke valve.

Another object of this invention is to provide a control for automatically closing and opening the choke valve of a carburetor wherein closure of the valve is effected by a low engine suction and wherein the valve is held in its open position during the normal running conditions of the engine to prevent closure ofthe choke valve whenever the suction drops momentarily as in accelerating the engine.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly dened by the appended claims, it being understood that such changes in the precise embodiment of the herein disclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiment of the invention constructed according to the best mode so far devised lfor the practical application of the principles thereof, and in which:

Figure 1 is a side view showing part of a conventional internal combustion engine and illustrating the application of this invention thereto;

Figure 2 is an enlarged longitudinal section view through the controlling device taken on the plane of the line 2 2 of Figure 1;

Figure 3 is a cross section view taken through Figure 1 on the plane of the line 3 3; and

Figure 4 is a view similar to Figure 2, but with parts thereof in elevation and showing the elements of the control in another position.

Referring now more particularly to the accompanying drawing in which like numerals indicate like parts throughout the several views, the numeral 4 designates the intake manifoldof an internal combustion engine 5. A riser 6 forming part of the intake manifold mounts a carburetor l.

The carburetor 1, as is customary, has a fuel line 8 leading to it and an air inlet 9 controlled by a choke valve IIJ. As is well known, by controlling the admission of air entering the inlet 9, the fuel-air ratio of the fuel mixture is determined, and in starting, it is customary to close the choke valve so that a rich mixture will be drawn into the intake manifold.

Heretofore, many diierent means have been provided for controlling the choke valve automatically so that the broad provision of an automatic control for choke valves is not new. The present invention, however, provides automatic control for the choke valve in a new and novel manner characterized by the fact that the same medium which effects closure of the valve in starting also eiects the opening of the valve after the engine has attained normal running conditions.

For this purpose, the control of this invention comprises a cylinder II open at one end and closed at its other end, except for a small air bleed I2 passing through the end wall I3 of the cylinder.

Operating in the bore I4 of the cylinder is a piston I5 from which an arm I6 projects outwardly-of the open end of the cylinder. The arm I6 is connected by a link I1 to a crank arm IB fixed to the shaft of the choke valve I0.

The cylinder II is so mounted with respect to the location of the choke valve and the length of the link Il that when the piston I5 is in its innermost position shown in Figure 2, the choke valve I0 is in its fully closed position shown in full lines in Figure 1, and when the piston is lin its outermost position, as illustrated in Figure 4, the choke valve is fully'open as indicated in dotted lines in Figure 1.

An expansion spring I9 confined between the end wall I3 of the cylinder and the piston which may be cup shaped so as to embrace the spring, yieldingly urges the piston to its outermost position to normally hold the choke valve open.

To draw the piston I5 to its innermost position and thereby effect closure of the choke valve, the closedend of the cylinder is communicated through a duct 20 With the intake manifold 4.

As shown in Figures 2 and 4, the duct 2l) is connected to the cylinder II in communication with a port 2| which opens to a. transverse bore 22 in the end Wall I3 of the cylinder intersecting the bleed opening I2.

Between the bleed opening I2 and the port 2I, the transverse bore 22 is communicated with the interior of the cylinder through a port or passage 23. Slidably disposed within the transverse bore 22 is a plunger 24 yieldingly urged away from the port 2| by an expansion spring 25. 'Ihe action of the spring 25 is opposed by a thermostat in the form of a bimetallic strip 26 anchored to the body of the cylinder II as at 21 with its free end bearing against the outer end of the plunger 24.

Being thermally responsive, the bimetallic strip 26 determines the position of the plunger 24 in accordance with the ambient temperature of the strip, and inasmuch as the controlling unit is mounted in close proximity to the exhaust manifold 28 or a portion thereof, it follows that the controlling effect of the bimetallic strip 26 and consequently the position of the plunger 24 is dependent upon the thermal condition of the engine.

When the engine is cold, as in starting, the bimetallic strip 26 is flexed outwardly as shown in Figure 2 so that the plunger 24 is held by its spring 25 in a position allowing unrestricted communication between the interior of the cylinder and the intake manifold and at which a cross bore 30 in the plunger is out of line with the air bleed I2. Consequently, during the cranking of the engine, the suction within the intake manifold exerts an effect on the piston I5 which being of comparatively large diameter is acted upon by the relatively slight suction prevalent during cranking and is drawn to its innermost position to close the choke valve.

When the engine starts and begins to operate under its own power, the effect of suction within the intake manifold increases considerably. The effect of the increased engine suction now draws the plunger 24 inwardly against the action of its spring 25 to cover the passage I9 shutting off the cylinder from the intake manifold and disposing the cross bore 30 in the plunger in line with the air bleed I2 so that the piston I5 is free to be projected outwardly by its spring I9.

The inward motion of the plunger 24 in response to the increased engine suction is limited to properly align its cross bore 30 with the air bleed I2, by the engagement of a reduced inner end portion 3| with the bottom of the transverse bore 22 as shown in Figure 4.

Upon release of the piston I 5 from the effect of engine suction, it is projected outwardly as hereinbefore stated, by its spring I9. The outward projection of the piston I5 and consequently the position of the choke valve I0, however, is furiher controlled in accordance with the thermal conditions of the engine by means of a substantially hairpin shaped bimetallic strip 33 having one end anchored as at 34 and its other free end engaging one edge of the arm I6 which is provided with a series of steps 35.

The steps 35 are so disposed that the risers therebetween afford abrupt shoulders or abutments successively farther out from the axis of the cylinder so that as the free end of the bimetallic strip 33 moves outwardly the piston is permitted to move outwardly under the influence of its spring I9 to progressively close the choke.

The disposition of the metals of the bimetallic strip 33 is such that its free end moves outwardly as the ambient temperature rises. Hence, the opening of the choke is regulated in accordance with the thermal conditions of the engine, being permitted to open fully only when the engine has attained a normal operating temperature.

The device of this invention also provides for the sudden enrichment of the fuel mixture during acceleration as long as the engine is cold, as sudden acceleration is accompanied by a decrease in engine suction. -If this occurs while the engine is still cold and the thermostatic controlling strip 26 is still flexed outwardly as shown in Figure 2, it follows that the plunger 24 will be moved outwardly by its spring 25 allowing engine suction to again act on the piston I5 and draw the same inwardly to fully close the choke valve from whatever position it is held by the thermostat 33.

Obviously after the engine warms up and the controlling thermostat 26 straightens out as shown in Figure 4, the loss in engine suction as a result of acceleration has no effect upon the choke valve as the plunger 24 is then held in its innermost position.

From the foregoing description taken in connection with the accompanying drawing, it will be readily apparent to those skilled in the art to which this invention appertains, that this invention affords novel means for automatically controlling the position of the choke valve of an internal combustion engine carburetor, and that the same medium which is utilized to effect closure of the valve is also utilized to effect the opening thereof.

What I claim as my invention is:

1. In combination with an internal combustion engine having a carburetor and a normally open choke valve for controlling the admission of air into the carburetor, an automatic control for the choke valve comprising fluid pressure responsive means operable upon a differential in fluid pressure created by the engine during cranking f the engine for closing the choke valve, and another fluid pressure responsive means operable by a greater differential in said fluid pressure created by the engine during operation thereof under its own power operable to disconnect said flrst mentioned fluid pressure responsive means from the source of pressure differential whereby the choke valve is completely freed from the holding effect of said first mentioned fluid pressure responsive means.

2. In combination with an internal combustion engine having a carburetor provided with a choke valve for controlling the admission of air into the carburetor, means for yieldingly urging the choke valve toward open position, and an automatic control for closing the choke valve during starting of the engine comprising a member connected with the valve and movable to close the same, fluid pressure responsive means for moving said member upon a predetermined differential in fluid pressure created by the engine during cranking, and another fluid pressure responsive means operable upon an increased differential in said fluid pressure resulting from operation of the engine under its own power operable to disconnect said first named fluid pressure responsive means from the source of pressure differential whereby the choke valve is completel freed from the holding effect of said first mentioned fluid pressure responsive means so that the choke valve is moved toward open position by the yieldable means as the engine begins to operate under its own power.

3. In combination With an internal combustion engine having a carburetor and a normally open choke valve for controlling the admission of air lli into the carburetor, means responsive to fluid pressure created by the engine during cranking thereof for closing the choke valve, and means responsive to fluid pressure created by the engine when the same is running under its own power for disconnecting said first mentioned fluid pressure responsive means from the effect of the fluid pressure.

4. In combination with an internal combustion engine having an intake manifold and a carburetor having a normally open choke valve for controlling the admission of air into the carburetor, means operable by suction created within the intake manifold by the engine during cranking for closing the choke valve, and means operable by the greater suction within the intake manifold created by the engine during operation thereof under its own power for disconnecting said first mentioned suction operated means from the source of suction.

5. In combination with an internal combustion engine having a closed system within which a partial vacuum is created by the engine and a carburetor provided with a choke valve for controlling the admission of air into the carburetor, yielding means for holding the choke valve open, means responsive to the effect of suction within said closed system during cranking of the engine for closing the choke valve, and means responsive to the effect of greater suction within said closed system during the running condition of the engine for disconnecting said first named suction responsive means from the source of suction.

6. In combination with an internal combustion engine having a closed system within which a partial vacuum is created by the engine and a carburetor provided with a choke valve for controlling the admission of air into the carburetor, yielding means for holding the choke valve open, means responsive to the effect of suction within said closed system during cranking of the engine for closing the choke valve, means responsive to the effect of greater suction within said closed system during the running condition of the engine for rendering said first named suction responsive means ineffective to hold the choke valve open, and thermally responsive means for holding said last named suction operated means in its operative position regardless of decrease in engine suction as long as a predetermined temperature condition obtains at said thermally responsive means, whereby closure of the choke valve after the engine is operating normally and has reached normal operating temperature is prevented.

'7. In combination with an internal combustion engine having means within which the engine creates a partial vacuum and having a carburetor provided with a choke valve for controlling the admission of air into the carburetor, yielding means for holding the choke valve open, a cylinder, a piston operating in the cylinder, means connecting the piston with the choke valve, means for communicating the cylinder with the means in which the engine creates a partial vacuum so that upon the establishment of a partial vacuum within said means during cranking of the engine the piston is moved to a position closing the choke valve, and means responsive to a higher vacuum created within said means by the engine operating under its own power for closing off communication between the cylinder and said means within which a vacuum is created to render said piston ineffective to hold the choke valve closed.

8. In combination with an internal combustion engine having means to create a fluid pressure differential and having a carburetor provided with a choke valve to control the admission of air into the carburetor, means for controlling the choke valve from variations in pressure differential, comprising a cylinder having a port through which the effect of fluid pressure differentials created by the engine are manifested within the interior of the cylinder, a piston operating in the cylinder in response to such fluid pressure differential, a connection between the piston and the choke valve whereby actuation of the piston in one direction closes the choke valve,

yielding means for opposing the motion of the? piston in response to fluid pressure differential and for normally holding the choke valve openjr a second cylinder in which the effect of the same fluid pressure differential is manifested, a second piston operating in said second cylinder, said second piston being adapted for closing the port of the first mentioned cylinder and being responsive only to a greater pressure differential than that at which the rst mentioned piston responds whereby the first piston acts to close the choke valve in response to low fiuid pressure differentials prevalent during cranking of the engine and the second piston acts to render the first mentioned piston ineffective to hold the choke valve closed upon the attainment of a hight' er fluid pressure differential as a result of the engine operating under its own power.

9. In combination with an internal combustion engine having means for creating a fluid pressure differential and a carburetor provided with a choke valve for controlling the admission of air into the carburetor, an automatic control for the choke valve comprising a cylinder provided with a port through which the effect of the fluid pressure differential created by the engine is introduced to the, interior of the cylinder, a piston operating in the cylinder and responsive to a fluid pressure differential prevalent during cranking of the engine, a connection between said piston and the choke valve whereby response of the piston closes the choke Valve during cranking of the engine, and means responsive to a higher fluid pressure differential obtained during normal running of the engine for closing said port to release the piston from the effect of the fiuid 1 pressure differential, and means for yieldingly urging the choke valve toward open position at all times so that upon release of the piston from the effect of the fluid pressure differential the choke valve is moved toward open position.

10. In combination with an internal combustion engine having means for creating a fluid pressure differential and a carburetor provided with a choke valve for controlling the admission of air into the carburetor, an automatic control for the choke valve comprising a cylinder, a connection leading to the cylinder through which the effect of a fluid pressure differential created by the engine ismanifested within the cylinder, a piston operating in the cylinder and responsive to a low fluid pressure differential established within the cylinder, means connecting the piston with the choke valve whereby response of the .piston closes the choke valve, a second cylinder, means connected with the second cylinder through which the effect of the fluid pressure differential created by the engine is manifested within said second cylinder, a piston operating in the second cylinder and responsive to a high fluid pressure differential for movement to a position shutting off the first mentioned cylinder from the effect of the fluid pressure differential to thereby release the first mentioned piston for movement to a position allowing opening of the choke valve, and spring means to yieldingly urge the choke valve toward open position.

11. In a device of the character described, a cylinder, a piston in said cylinder, the cylinder having a port through which a fluid preessure differential at opposite sides of the piston may be established for moving the piston in one direction, a spring yieldingly urging the piston in a direction opposite the direction of motion of the piston in response to the liuid pressure differential at opposite sides of the piston, another cylinder of smaller cross sectional area than the first mentioned cylinder, and another piston operating in said other cylinder, said other cylinder having means through which a fluid pressure differential may be established at opposite sides of said other piston so that said other piston is movable in response to a higher fluid pressure differential than that at which the first piston operates to a position closing said port whereby the first mentioned cylinder is shut off from the effect of fluid pressure so that the first mentioned piston is free to be operated by its spring.

l2. In a device of the character described, a cylinder open at one end and having an end wall closing its opposite end, said end wall having an air bleed for communicating the closed end portion of the cylinder with the atmosphere and having a port through which uid pressure may be introduced into the interior of the cylinder, a piston operating in the cylinder and movable in one direction by fluid pressure introduced into the cylinder through said port, a spring to oppose such motion of the piston, a second cylinder provided by a bore in the end wall intersecting the air bleed and communicating with said port so that said second cylinder is subjected to the same fluid pressure as the first cylinder, and a piston operating in said second cylinder and movable in response to a predetermined fluid pressure in said second cylinder to a position closing the port leading to the first mentioned cylinder and opening the air bleed, whereby the first mentioned piston is released for actuation by its spring means.

13. In combination with an internal combustion engine having an intake manifold within which the engine creates a partial vacuum and a carburetor provided with a choke valve adapted for controlling the admission of air into the carburetor, an automatic control for the choke valve comprising a cylinder provided with an end wall, said end wall having an air bleed for communicating the interior of the cylinder with the atmosphere and having a port communicating with the interior of the cylinder, said end wall also having a bore intersecting said air bleed and communicating with said port, said bore providing a second cylinder, means for communicating said bore with the intake manifold whereby both cylinders are subjected to the effect of vacuum Within the intake manifold, a piston operating in the first cylinder in response to low vacuum, means connecting said piston with the choke valve so that response of Said piston to low vacuum closes the choke valve, means to yieldingly urge the choke valve toward open position. a second piston operating in the second cylinder and biased to a position closing the air bleed and allowing unrestricted communication between the port and said second cylinder, said second cylinder and the second piston operating therein being of smaller cross sectional area than the first cylinder and piston so as to respond only to a higher vacuum in the intake manifold, and saidsecond piston moving in response to a higher vacuum to a'position closing said port and opening the air bleed, whereby the first designated piston is free from the effect of vacuum for actuation by its yieldable urging means.

14. In combination with an internal combustion engine having an intake manifold within which the engine creates a partial vacuum and a carburetor provided with a choke valve adapted for controlling the admission of air into the carburetor, an automatic control for the choke valve comprising a cylinder provided with an end wall, said end wall having an air bleed for communieating the interior of the cylinder with the atmosphere and having a port communicating with the interior of the cylinder, said end wall .also having a bore intersecting said air bleed and communicating with said port, said bore providing a second cylinder, means for communicating said bore with the intake manifold whereby both cylinders are subjected to the effect of vacuum within the intake manifold, a piston operating in the first cylinder in response to low vacuum, means connecting said piston with the choke valve so that response of said piston to low vacuum closes the choke valve, means to yieldingly urge the choke valve toward open position, a second piston operating in the second cylinder and biased to a position closing the air bleed and allowing unrestricted communication between the port and said second cylinder, said second cylinder and the second piston operating therein being of smaller cross sectional area than the first cylinder and piston so as to respond only to a higher vacuum in the intake manifold, and said second piston moving in response to a higher vacuum to a position closing said port and opening the air bleed, whereby the first designated piston is free from the effect of vacuum for actuation by its yieldable urging means, and thermostatic means to control the opening of the choke valve upon release of the first designated piston from the effect of vacuum.

15. In combination with an internal combustion engine having an intake manifold within which the engine creates a partial vacuum and a r carburetor provided with a choke valve adapted for controlling the admission of air into the carburetor, an automatic control for the choke valve comprising a cylinder provided with an end wall, said end Wall having an air bleedfor communicating the interior of the cylinder with the atmosphere and having a port communicating with the interior of the cylinder, said end wall also having a bore intersecting said air bleed and communicating with said port, said bore providing a second cyclinder, means for communicating said bore with the intake manifold Whereby both cylinders are subjected to the effect of vacuum Within the intake manifold, a piston operating in the first cylinder in response to low vacuum, means connecting said piston with the choke valve so that response of said piston to low vacuum closes the choke valve, means to yieldingly urge the choke valve toward open position, a second piston operating in the second cylinder and biased to a position closing the air bleed and allowing unrestricted communication between the port and said second cylinder, said second cylinder and the second piston operating therein being of smaller cross sectional area than the rst cylinder and piston so as to respond only to a higher vacuum in the intake manifold, and said second piston moving in response to a. higher vacuum to a position closing said port and opening the air bleed, whereby the rst designated piston is free from the effect of vacuum for actuation by its yieldabie urging means, and thermostatic means operable upon the attainment of a predetermined ambient temperature for holding the second designated piston in its position to which it moves in response to vacuum.

JOHN W. Fl'rz GERALD,

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