US2245093A - Automatic choke control - Google Patents

Description

June 10, 1941.

A. w. MESTON' 'AUZOMATIC CHOKE CONTROL Filed Jan. 16, 1932 2 Sheets-Sheet 1 rial- INVENTOR Y ALECK w. MESTON av HIS ATTORNEYS Patented June 19, 1941 AU'EGREATK'C CHQZXE GENE RG14 Aleck W. Meston, Toledo, Ohio, assignor to Mote Meter Gauge & Equipment Corporation, Toledo, Ohio, a corporation of Delaware Application January 16, 13-32, Serial No. 587,997

(Cl. res-4.1a)

1d Claims.

This invention relates to automatic choke controls, and more particularly to a control mechanism of this character for automatically controlling a choke valve such as is customarily provided for the air irlet pipe of an internal combustion engine.

Objects of the invention are to simplify and improve the construction and operation of control mechanisms of this character, to render the same compact and convenient to install, economical to manufacture, reliable in use, not likely to get out of order, and otherwise well adapted for the purpose intended.

Other objects and features of novelty will be apparent as the following description proceeds, reference being had to the accompanying drawings, in which Figure l is an elevation of an internal combustion engine provided with the automatic choke valve control;

Figure 2 is an enlarged detail section through the air inlet pipe of the engine, taken along the line ?.2 of Figure 4 and showing the details of th control mechanism;

Figure 3 is a detail elevation of a part of the engine shown in Figure 1, showing a modified mounting for the temperature responsive bulb;

Figure 4 is a horizontal section taken along the line 5- of Figure 2, showing th choke control mechanism in plan;

Figure 5 is a section similar to Figure 2, taken along the line 5-5 of Figure 6, and showing a modified mechanism; and

Figure 6 is a view similar to Figure 4, showing the modified mechanism in plan.

An internal combustion engin it is shown in re 1, and is provided with an inlet manifold H, a carburetor ii, an air inlet pipe l3, and a cooling system, which is represented by a water jacket l4 surrounding the cylinder block of the engine. As shown in Figure 2, the air inlet pipe I3 is provided with a choke valve l5 which is of the vane or butterfly type, being mounted on a shaft 13 which is pivoted in the walls of the pipe l3.

The choke control mechanism is adapted to open the valve 15 in response to the suction in the engine inlet manifold ll. Accordingly, a fluid pressure responsive device is mechanically connected to the choke valve 15, and pneuma J ically connected to the inlet manifold of the engine, by means of a tube is shown in Figures 1, 2 and 3.

In the form shown, the fluid pressure responsive device comprises a cylinder 19 provided with 5;

a piston 28. The piston is provided with a pair of ears 22, between which is pivoted one end of a link 23, the other end of which is pivoted in a socket 2 3 formed in the blade of the choke valve iii. A spring is mounted in the cylinder [9 under the piston 2b. This spring is seated in a cup the central portion of which is dished inwardly to receive the end of an adjusting screw El, by means of which the compression of the spring may be adjusted.

The automatic control of the choke valve I5 is also responsive to the temperature of the engine cooling system. The structure for this purpose is best shown in Figure 4. A Bourdon spring is mounted adjacent the inlet air pipe I3, and is connected by means of a capillary tube 32 with a bulb 33, which may be mounted in the water jacket M as shown in Figure 1, or may be mounted in a clip 34 secured under the head of one of the cylinder head bolts 35, as shown in Figure 3. The spring 3i), capillary tube 32, and bulb 3 3, as a unit, are filled with an expansible fluid, so that the Bourdon spring is responsive to the temperature of the cooling system. A free end of the spring Bil is connected to an arm 38, which is an extension of the link 23, and thus connects the Bourdo'n spring to the valve l5 for operating the same.

The Bourdon spring 38 is preferably fixed to the side of the air inlet pipe at its central portion, thus leaving two free ends 37 and 38, and the added motion of both ends is applied to open the chok valve. In Figure 4 the free ends are connected by a spring bronze wire 39 which has a catenary action. The central'portion of the wire as is received in a slot 4!] formed in the extension arm 35 of the link 23, forming a lost motion connection.

In Figure 6 a more positiv connection is provided between the Bourdon spring and the valve 5. One end of the link A! is pivoted to the free .nd 87, and one arm of a bell crank 62 is pivoted o the free end 33. The other end of the link i is pivoted to the intermediate pivot of the bell crank. The other arm of the bell crank 42 is slotted as at M to receive a lug 45 carried by the extension 3%; of the link 23. The slot 44 is elongated laterally merely to prevent binding of the linkage at this point.

The pipe it in. Figure 2 may be a sheet metal extension of the carburetor air inlet pipe, and a convenient mounting for the Bourdon spring 3%! may be provided by forming a tongue 46 extending from the rim of the pipe, and bending this tongue down over the Bourdon spring. The sheet metal construction is also of advantage in mounting the cylinder l9. A tongue 41 is struckoutward from the side of the pipe [3, and is turned up as at 48 and apertured to receive the screw 21, the cylinder being mounted on the tongue and extending laterally from the pipe. The forming of the tongue 2| leaves an aperture through which pass the connections from the piston 20 to the valve [5.

The automatic control mechanism may be mounted within an air cleaner casing which is best shown in Figure 2. This casing comprises a cup member 50 having a central aperture which is fitted over the pipe l3, and a perforated disk 5|, which is also apertured and fitted over the pipe, and crimped to the rim of the cup as at 51a. The annular space so formed is filled with material which will serve to trap dust and dirt for cleaning the air supplied to the carburetor, and also to act as a flame arrestor. Bronze wool is a satisfactory material for this purpose. The bottom of the cup 50 is also perforated to permit the air to pass therethrough after having been cleaned by the material in the casing.

A cover member 52 is provided over the open end of the pipe l3 which is surrounded by the cup member 50, and the rim of the cover 52 fits over the edge of the member 56 and is secured thereto by screws 53. The space within the cover 52 above the cup member 50 and outside of the inlet air pipe l3, contains both the cylinder l9 and the Bourdon spring 3!). Thus the mechanism is protected from dust, dirt and other conditions, and at the same time the mechanism is readily accessible for inspection or adjustment.

In operation, assuming that the engine is cold and that the choke valve I5 is closed, when the a suction in the manifold l I, which suction, trans-.

mitted to the cylinder l9, slightly retract the piston and tends to open the valve 15. This condition, of course. supplies a greater proportion of air to the cylinders of the engine and thus prevents flooding of the carburetor.

If the engine is very cold, and this opening of the valve supplies too much air, so that the engine tends to stall, this condition will decrease the suction in the manifold II and the cylinder I9, thus permitting the spring to partially close the valve and thus enrich the mixture. When the engine has started and is operating under its own power, the valve !5 is maintained open or partly open by the suction as described.

As long as the engine runs smoothly under light load and at relatively slow speed there is a high vacuum in the intake manifold and the valve stays open or partly open. If, however, the engine fails to run smoothly or is put under load or accelerated, the vacuum will drop and the valve will close in a corresponding degree. This operation provides the enrichment of mixture required by a cold motor for pulling or for acceleration. The provision for choking the air supply instead of adding more fuel to the air fuel mixture as delivered by the carburetor aids vaporization of the liquid fuel and gives a smoother performance during the warm-up period.

The operation of the choke control mechanism is also subject to the action of the temperature responsive device. When the engine is cold, even after it has been started and is operating under its own power, the cooling system is still cold, and hence the Bourdon spring 3!! may not tend to open the valve [5. As the engine warms up, however, the expansible fluid in the bulb 33 expands and causes expansion of the Bourdon spring. The catenary action of the wire 39 after it reaches the end of the slot 40 tends to further open the valve. In the form shown in Figures 2 and 4, the lost motion afforded by the slot 40 permits opening of the valve by the suction device, without interference from the Bourdon spring.

With the form shown in Figs. 5 and 6, the spring 25 is designed to have less strength, part of the function of the spring being performed by the inherent spring action of the Bourdon spring 30. Thus when the engine has started, the suction developed in the manifold l I applied to the cylinder It? tends to open the choke valve, but this action is opposed by the Bourdon spring 3!! and the spring 25. However, the spring 25 offers so little resistance that the suction is suflicient to overcome the Bourdon spring and open the valve [5 to the desired extent.

In both forms of the invention, the Bourdon spring is not compensated for atmospheric temperature. Hence the operation of the temperature responsive device is modified by atmospheric temperature. In other words, the Bourdon spring is responsive to a differential temperature between the cylinder head and the surrounding air.

It should be noted that the pivot i5 is off center with respect to the pipe !3. This arrangement causes the engine suction of the air passing through the pipe I3 to assist the automatic control in opening the valve.

While several embodiments of the invention have been disclosed, the invention is not limited to the details thereof, but instead embraces such embodiments as fall within the scope of the appended claims.

I claim.

1. In combination with a choke valve associated with the air inlet pipe of an internal combustion engine having a cooling system and an inlet manifold, means responsive to the temperature of said cooling system for opening said valve, a cylinder mounted on said pipe, a piston in said cylinder, and a bell-crank pivoted on the piston,

one arm being connected to said valve and the other arm to the means responsive to temperature, said cylinder being connected to said inlet manifold, whereby said piston is responsive to suction of said manifold for opening said valve.

2. In combination with a choke valve associated with the air inlet pipe of an internal combustion engine having a cooling system and an inlet manifold, a Bourdon spring mounted on said air inlet pipe and responsive to temperature of said cooling system, a cylinder mounted on said pipe and containing a piston responsive to suction of said manifold, and a member connected to said valve and to said piston and having a portion connected to said'Bourdon spring.

3. In combination with a choke valve associated with the air inlet pipe of an internal combustion engine, having an inlet manifold and a cooling system, means responsive to temperature of said cooling system modified by atmospheric temperature for opening said choke valve, and a fluid pressure responsive device actuated by said suction in said manifold and connected to said valve for opening the same.

4. In combination with a choke valve associated with the air inlet pipe of an internal combustion engine having a cooling system and an inlet manifold, an air cleaner casing associated with said air inlet pipe, means responsive to the temperature of said cooling system and a fluid pressure device actuated by suction in said inlet manifold both mounted in said air cleaner casing and both connected to said choke valve for operating the same.

5. In combination with a choke valve associated with the air inlet pipe of an internal oombustion engine having an inlet manifold, and an air cleaner casing associated with said air inlet pipe, a fluid pressure device mounted inside of said air cleaner casing and outside of said air inlet pipe, a tube connecting said fluid pressure device to said inlet manifold, and means connecting said fluid pressure device to said choke valve for operating the same.

6-. In combination with a choke valve associated with the air inlet pipe of an internal combustion engine having a cooling system, and an air cleaner casing associated with said air inlet pipe, a temperature responsive device mounted inside of said air cleaner casing and outside of said air inlet pipe, a tube connecting said temperature responsive device to said cooling systern, and means connecting said temperature responsive device to said choke valve for operating the same.

7. In combination with a butterfly choke valve pivoted in the air inlet pipe of an internal combustion engine having an inlet manifold, means for supporting an annular air cleaner element in position surrounding said air inlet pipe, a cover over said air cleaner element and the open end of said pipe, whereby incoming air passes in one direction in an annular path through said air cleaner element and enters said inlet pipe in the opposite direction, a fluid pressure device mounted in said cover, a tube passing through said cover from said fluid pressure device to said manifold whereby said device is responsive to suction in said manifold, and means actuated by said device and passing through said air inlet pipe for turning said choke valve on its pivot.

8. In combination with a butterfly choke valve pivoted in the air inlet pipe of an internal combustion engine having a cooling system, means for supporting an annular air cleaner element in position surrounding said air inlet pipe, a cover over said air cleaner element and the open end of said pipe, whereby incoming air passes in one direction in an annular path through said air cleaner element and enters said air inlet pipe in the opposite direction, a temperature responsive device mounted in said cover, a tube passing through said cover from said device to said cooling system for operating said device therefrom, and means actuated by said device for turning said choke valve on its pivot.

9. In combination with a butterfly choke valve pivoted in the air inlet pipe of an internal combustion engine having an inlet manifold and a cooling system, a Bourdon tube responsive to temperature of the cooling system having one portion rigidly secured to the outside of the air inlet pipe adjacent the end thereof, said Bourdon tube extending transversely of the pipe and partially embracing the pipe, fluid pressure means responsive to suction in the manifold of the engine mounted transversely on the pipe to act in a line parallel to the line of action of the Bourdon tube, and a member connected to the valve and the fluid pressure means, and having a portion connected to an end of the Bourdon tube whereby the valve is positioned in response to the action of the Bourdon tube and the fluid pressure means.

10. In a device of the class described, an air inlet pipe of an internal combustion engine, a choke valve unsymmetrically pivoted in the inlet pipe, a Bourdon tube attached adjacent the end of the pipe having two arms extending symmetrically about the pipe transversely thereof, fluid pressure means mounted transversely of the pipe in a plane between the plane of the Bourdon tube and a transverse plane of the tube running through the pivotal point of the valve, a bell-crank pivoted in the plane of the fluid pressure means and extending on one end into the plane of the Bourdon tube and attached at the other end to the valve at a point displaced from the pivotal point of the valve, means cooperating with the bell-crank and the ends of the Bourdon tube in the plane of the Bourdon tube, and means establishing a relation between the pivotal point of the bell-crank and the fluid pressure means, whereby the choke valve is positioned'at a point bearing a relation to the position of the Bourdon tube and the position of the fluid pressure means.

{ ALECK W. MESTON.

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