US2327903A - Automatic choke mechanism and choke valve - Google Patents

Description

Aug. 24, 1943. c. H. JORGENSEN AUTOMATIC CHOKE MECHANISM AND CHOKE VALVE Filed Oct. 17 1934 2 Sheets-Sheet 1 ATTORNEYS 1943- c. H. JORGENSEN AUTOMATIC CHOKE: MECHANTSM AND CHOKE VATJVF 2 Sheets-Sheet 2 3 Filed Oct. 17, 1934 INVENTOR ZE -W 44 Patented Aug. 24, 1943 AUTOMATIC CHOKE MECHANISM AND CHOKE VALVE Clarence H. Jorgensen, Anderson, Ind., asslgnor to General Motors Corporation, Detroit, Micla, a

corporation of Delaware Application October 17, 1934, Serial No. 748,805

13 Claims.

This invention relates to an automatic choke mechanism for automatically controlling the choke or air intake valve 01' a charge forming device for an internal combustion engine to facilitate starting of the engine and to a novel form of choke valve.

It is an object of the present invention to provide an automatic choke mechanism in which the choke valve is controlled by the ioint action of engine suction and thermally responsive means which is so designed that the valve is positioned by said thermally responsive means to increase the proportion of fuel in the cambustible mixture inversely in accordance with the temperature adiacent said thermally responsive means and is operable by engine suction to decrease the proportion of fuel in the combustible mixture upon increase of suction effective on said valve.

It is a further object of the invention to provide a choke valve having a part adapted to completely close the air intake passage when in closed position and may be moved to position to fully open the intake passage, and is provided with a second part which is movable independently of the first mentioned part, but is resiliently held in position to restrict the air intake passage when said first mentioned part is in partly opened position.

It is a further object of the invention to provide a choke valve constructed as set rorth in which the second mentioned part is movable by the blast of the entering air when the first mentioned part is in partly opened position and to provide means to positively move the said second mentioned part to a position where it does not restrict the intake passage at all when the first mentioned part of said valve is in iully open position.

It is a still further object of the invention to provide a choke valve of the type described and means'for positively positioning the first mentioned port of said valve by means of a thermally responsive device and by means of engine suction in the manner previously set forth.

Further objects and advantages oi the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a side elevation oi an intake manifold and carburetor unit in which a choke valve and operating mechanism therefor constructed in accordance with the present invention is embodied.

Fig. 2 is an end elevation of the manifold and carburetor.

Figs. 3, 4 and 5 are detail sections through the air intake of the carburetor showing the choke valve in different positions.

Fig. 6 is a section on the line 6-8 of Fig. 1.

Fig. 7 is a detail section on line 1-1 of Fig. 4.

Referring to the drawings, the intake manifold is indicated at in and is provided with a hot spot i2, to which is secured a downdraft carburetor unit it, that illustrated in the drawings being the well known Carter carburetor which need not be described in detail. The carburetor unit is provided with a main housing it in which the main intake passage is located and received in the upper end of this housing is an air intake coupling II in which the choke valve herelnaiter described is positioned. Shown in Fig. 2 is an operating arm 20 secured to the end of a spindle 22 on which is mounted a throttle valve (not shown) of ordinary construction which regulates the flow of combustible mixture to the engine in the usual manner.

Joumalled in the intake coupling i8 is a spindle 24 to the flat portions of which adjacent the ends is secured a choke valve 28 which is of such size as to completely close the intake passage as shown in Fig. 4. Associated with the valve 2| is a half valve :0 which is adapted when the choke valve 26 is in the position shown in Fig. 4 to be held against a shoulder Ill, formed on the inner wall of the air intake coupling. by a spring 8!. one end of which is attached to a pin l4 extending from the hall valve and at its other end to a similar pin 30 projecting from the main choke valve 18.

The main valve It is rigidly secured to the spindle 24 by screws while the hall valve 28 is rotatable with respect to said spindle. To this end the main valve 28 is provided with an opening 38 at the middle part thereof and through this opening an extending tongue 40 of the half valve is projected being bent into cylindrical form as shown in the drawings so that it is rotatably Journalled on a cylindrical portion of the spindle 24 formed at the middle part thereof and fits sufllciently loosely to rotate freely thereon.

The hub portion of the half valve has a raised portion at the center which may be formed by brazing a separate piece to the hub or in any other suitable way and is provided with a series of orifices I! which cooperate with gear teeth 44 formed on the end of an arm l8 pivotally mounted by a pin It on an arm Bil secured to the valve 28 by pins 52.

The operation of this valve mechanism is substantially as iollows. when the valve is in closed osition. the parts are in the position shown in Fig. 4, the spring 42 holding the half valve ll against the shoulder 40 as previously described. When the main valve 24 is moved to partly open position, by means to be presently described. the parts assume the position shown in Fig. 5. It will be noted that in this position or the main valve the half valve may lay behind the main valve to restrict the intake passage to a greater degree than the main valve as shown in said Fig. 5, or may move to a postion to restrict said passage to the same degree as does the main valve, the position of the hall valve being dependent on the air pressure effective thereon, its opening movement being opposed by the action of the spring 42.

When the valve 28 is moved to iull open position, as shown in Fig. 3, the arm 46 is moved into engagement with the inner surface of the air intake coupling with the result that such arm is rotated on its pivot in a counter-clockwise direction and through engagement of teeth 44 with orifices 42, rotates the half valve Ill to the position shown in Fig. 3, regardless of what degree of suction may be eflective on such valve.

It should be noted that the spindle 24 is mounted somewhat to one side of the intake passage so that the valve 28 is somewhat oil center. Therefore, the air pressure eflective on the valve itself tends to move it toward open position as well as the suction operated means which has been previously referred to and will be described in detail later.

The position of the main valve is primarily determined by the automatic choke mechanism previously referred to, and to this. end an operating arm 54 is secured to one end oi the spindle 24, said arm being pivotally connector! to a link 58 which at its opposite end is pivotally connected to an operating arm 54 secured in\ any desirable way to one end of a shaft 80 suitably journalled in a housing 82. The housing i2 is provided with a detachable bottom 83 secured in position by tanks 63a and secured to a. plate 64 adapted to be secured to the previously mentioned hot spot by machine screws 64 or in any other desirable manner. A gasket 05 is provided between the plate and the manifold, above the housing 62 and secured thereto in any desirable way is a cylindrical housing 48 in which is received a Sylphon bellows 14, the function of which will be more fully described later.

A thermostat 12 is provided which is connected at one end to the shaft 60 as shown in Fig. 6 and at its other end is connected to pin 14 projecting irom a connecting link 16 which is pivotally connected at its upper end to a. pin 18 carried by the two depending arms of a yoke 80 secured to the solid head 82 which forms the bottom of the Sylphon bellows 10, the yoke extendmg downwardly through an opening 84 in the top aaamoa wardly -and this motion is opposed by the coil spring D4 which is received within the bellows.

'Io communicate the engine suction to the interior of. the bellows there is provided b suction conduit I4 which. at.one end communicates with a central bore 48 formed within the nipple II and communicating at no end with the interior of the bellows. An adi table tapered metering valve 48 is received within the bore 04 and may be adlusted to determine the rate at which air is exhausted from the bellows and therefore. can determine the rate at which the head 82 of the bellow is pulled upwardly. The suction conduit at the opposite end extends through the plate 64 and registers with a suitable suction passage (not shown) in the wa'll of the manifold which communicates with the interior thereof.

Secured at the end of shaft 40 opposite to that on which the arm 58 is securedand within the housing 62 i an operating arm I" which is used merely for calibration purposes. A-suitable opening (not shown) is formed in the bottom I of housing 82 to communicate atmospheric pressure to the bottom head 82 of the Sylphon to force the head upwardly when a subatmospherlc pressure is created within the bellows.

There may be formed in the lower end of the link 18 an opening liil to which a manual operating connection for the choke may be connected and an opening it! may be provided in the bottom plate I for such operating connection to extend through if 'desired.

Means are provided to adiustably determine the position of the throttle valve at idling in acoordance with the position of the choke. For this purpose a link HO has a bent over upper end which extends through a suitable hole in the operating arm. At its lower end this link proiectg through the horizontal portion of an angle bar H! which has a vertical portion slidable in any form of suitable guiding means. The guiding means may be a track formed in the carburetor housing or may be a separate bracket H4 secured by a screw or other suitable means to the carburetor housing. The vertical portion of the element H2 slides in such guide means. The link is provided with an adjustable collar H4 above the horizontal portion of the bar H2 and received between this bar and a washer I I! at the lower end of the link is a spring I" which normally retains the bar ill in contact with said shoulder as shown in Fig. 2. The lower end of the angle bar is tapered as indicated at 2 and this tapered end cooperates with a screw I24 carried by the throttle operating arm II.

The operation of this idle control mechanism is as follows. The link H0 moves with the main portion of the choke valve and its position at idling is determined by the thermostat. If the engine is cold it is held in its lower position and the collar H6 moves the angle bar H2 downwardly so that some part'of its tapered lower end is opposite the screw I24 which will determine the closed or idling position of the throttle. If it is cold, a thicker portion of the tapered end of angle bar H2 is opposite screw I24 than if the temperature i higher because link H0 is in lower position. This will result in a wider open throttle and faster idling than when the temperature is higher.

In the construction shown, the link H0 can move upwardly without movement of the angle bar. This construction is provided so as to permit opening of the choke during the warm up period if the throttle remains in idling position.

The operation of the automatic operating mechanism for the valve 26 is as follows. If it be assumed that the engine and surrounding atmosphere are relatively cold, the thermostat is effective to hold the valve 28 in closed position, such position being determined by the thermotat. As the engine is turned over by the Itarting motor, suction is communicated to the bellows II and if the engine fails to start for any appreciable time, the auction in the bellows will build up sumciently to open the valve 2. to admit enough air to prevent flooding.

When the engine starts to run, the suction efl'ective both on the bellows and on the valve ll increases and pulls the valve 28 open to a greater degree. At such time the spring held half valve II tends to lag behind the main valve owing to the spring tension which has to be overcome and prevents sumcient air entering to lean the mixture to a degree which will stall the engine or cause it to miss.

If the throttle is opened to accelerate during the warm up period, the suction eflective on the bellows falls while the suction directly eii'ective on the valve itself increases with the result that the valve is moved toward open position notwithstanding the drop in suction in the bellows. Under these conditions the half valve 28 also tends to restrict the passage to a greater degree than the valve and so is efl'ective to prevent too much leaning of the mixture during acceleration.

After the engine has warmed up suiliciently, the thermostat operates to move the parts to the position shown in Fig. 3 in which position the half valve has no restricting eflect on the intake pasaage whatever.

With a spring 32 of proper tension the auxiliary or half valve steps up the fuel proportion in the mixture just enough to give smooth idling and part throttle operation, as well as proper acceleration performance during the warm up period. In plain tube carburetors there is a noticeable "fiat spot" fer of fuel flow from just at the point of transthe idle to main iuel lot, but this form of choke valve is eflective to eliminate this "flat spot substantially entirely.

While the embodiment oi the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other form might be adopted, all coming within the scope oi the claims which follow.

What is claimed is as follows:

1. A choke valve for carburetors having an air intake passage, comprising a larger main part and a smaller secondary part, said main part being constructed to constitute the greatest restriction to flow of air to the intake passage when the valve is in closed position and means for causing said secondary part to restrict the flow of air into the said passage to a greater degree than the main part of said valve when the valve is partly open.

2. An unbalanced choke valve for internal combustion engines adapted to be operated by the air pressure thereon and comprising a main part and a secondary part movable independently of and relatively to the said main part, both parts of said valve being movable by the effect of air pressure, and resilient means controlling the movement of said secondary part relative to the main part so that the secondary part tends to lag behind the main part as the valve is opened 3 for the purpose of restricting the flow of air into the intake passage to a greater degree than the main part of such valve.

3. Achokevalvesuchasdeiinedin claimiin combination with thermally responsive means directly with said main part of the valve for operating said valve.

4. A choke valve such combination with limit the closing movement oi the throttle valve so as to determine the idling position of the throttle in accordance with the position of said main part of the choke valve.

6. In a carburetor having an air intake passage, a choke valve in said passage and operable to control the flow of air therethrough, thermally responsive means controlling the opening of said choke, a throttle valve, a movable throttle stop device, mechanism operable by the choke valve for positioning said step device, said mechanism being so constructed that said device is moved to a fast idle position when said choke is closed, to prevent full closing movement of said throttle valve and to permit faster than normal idling of the engine, and is movable to an inoperative position during opening movement of said choke valve and substantially before said choke valve is fully opened, said mechanism being constructed to permit at least partial opening of said choke valve without moving said stop device from said fast idle position.

7. In a carburetor having an air intake passage, a; choke valve in said passage and operable to control the flow of air therethrough, means for positioning s d choke valve in accordance with engine tempe ature and suction, a throttle valve, a movable throttle stop device, mechanism operable by the choke valve for positioning said stop device, said mechanism being so constructed that said device is moved to a fast idle position when said choke is closed, to prevent full closing movement of said throttle valve and to permit faster than normal idling of the engine, and is movable to an inoperative position during opening movement of said choke valve and substantially before said choke valve is fully opened, said mechanism being constructed to permit at least partial opening of said choke valve without moving said stop device from said fast idle position.

8. A choke valve construction for carburetors having an intake passage, said valve comprising main and secondary portions, said main portion providing the principal restriction to the flow 0! entering air when the valve is closed, means for moving the said main portion of said valve toward at position to provide a minimum restriction on the how of air entering the carburetor and means tending to maintain the secondary portion of said valve in position to materially restrict the flow of entering air as the main portion oi the valve is so moved.

9. A choke valve construction for carburetors having an intake passage, said valve comprising main and secondary portions, providing the principal restriction to the flow oi entering air when the valve is closed. meant for moving the said main portion said valve toward a position to provide a minimum restriction on the now of air entering the carburetor and a resilient member tending to maintain the secondary portion oi said valve in position to materially restrict the flow of entering air as the main portion of the valve is so moved.

10. A choke valve construction for carburetors having an intake passage, said valve comprising main and secondary portions, said main portion providing the principal restriction to the how oi entering air when the valve is closed, means for moving said valve toward a position to provide a minimum restriction to the flow of air entering the intake passage, said means having direct connection with the main portion oi! said valve and a lost motion connection with the secondary portion of said valve whereby said main portion 0! the valve can be moved toward open position without corresponding movement of the secondany portion, and resilient means tending to hold said secondary portion of said valve in position to provide maximum restriction to the air flow as the main portion oi. said valve is moved toward a position to provide minimum restriction to the flow of air.

11. A choke valve construction for carburetors having an intake passage, said valve comprising main and secondary portions, said main portion providing the principal restriction to the flow of entering air when the valve is closed, means for moving said valve toward a position to provide a minimum restriction to the flow of air entering the intake passage, said means having direct connection with the main portion of said valve and a lost motion connection with the secondary portion of said valve whereby said main portion of the valve can be moved toward open position without corresponding movement of the secondary portion, and resilient means tending to hold said secondary portion of said valve in position to provide maximum restriction to the air flow as the main portion of said valve is moved toward a position to provide minimum restriction to the said main portion aeamos flow or air, and means operable when the main portion oi said valve reaches its full open or minimum now restricting position to move said secondary portion 0! said valve to its tail open position.

12. A choke valve construction for carburetors having an intake passage. said valve comprising main and secondary portions, said main portion providing the principal restriction to the iiow of entering air when the valve is closed, means for moving said valve toward a position to provide a minimum restriction to the flow of air entering the intake passage, said means having direct connection with the main portion of said valve and a lost motion connection with the secondary portion of said valve whereby said main portion of the valve can be moved toward open position without corresponding movement of the secondary portion, and resilient means tending to hold said secondary portion of said valve in position to provide maximum restriction to the air flow as the main portion of said valve is moved toward a position to provide minimum restriction to the flow of air, and a member carried by the valve assembly and operable when the main portion of said valve reaches its full open or minimum flow restricting position to move said secondary portion of said valve to its full open position, said member being operated by engagement thereof with the wall of the intake passage when the main portion of the valve reaches full open position.

13. In a carburetor having an air intake passage, a choke valve comprising a main part and a secondary part, and so constructed that said main part constitutes the principal restriction in the air intake passage under certain operating conditions, while the secondary part of said valve constitutes the greater restriction to the admission 01! air into said intake passage under other operating conditions, thermally responsive means for positioning the choke valve to increase the iuel proportion in the mixture inversely as to the temperature and means operable by engine suction to move the valve to decrease the proportion or fuel in the mixture.

CLARENCE H. J ORGENSEN.

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