US2793845A - Slow closing throttle device - Google Patents

Description

' y 1957 M. c. BROWN 2,793,845

SLOW CLOSING THROTTLE DEVICE Filed May 21, 1954 1 [I u I, H 34 24 III P: 30 "K 35 F|G2 FIG 3 INVENTOR. MORRIS C. BROWN ATTORNE United States PatentQ r signments, to ACE Industries, Incorporated, New York,

N. Y., a corporation of New Jersey Application May 21, 1954, Serial No. 431,312

9 Claims. (Cl.261--65) This inven'tionrelates to carburetors for internal combustionengines and, more speciflcally, to a novel mechanism to retard throttle closing and to enrich the mixture during subsequent throttle opening by increasing the level within the fuel bowl simultaneously by the closing action of the throttle.

The problem of supplying the proper mixture to several cylinders of an internal combustion engine from one or more carburetors is complex and requires many compromisesin carburetor design to compensate for limitations imposed by manifolding. One of these problems is caused-by condensation or precipitation of fuel on the manifold walls when the throttle is opened and manifold pressures suddenly increase. Unless during such time the carburetor supplies a very rich mixture to the manifold, the engine will receive a mixture too lean to fire and a noticeable hesitation in power output will result. The conventional engine-aspirated type of carburetor is accordingly usually equipped with some means to enrich the mixture during throttle opening. This means can be an accelerating pump or, in the case where the carburetor is equipped with a near horizontal fuel nozzle, a similar function can be obtained by employment of an accelerating well adjacent the nozzle. It is characteristic of the latter type of carburetor that the accelerating well is sensitive to fuel level, and will not operate satisfactorily on initial throttle opening unless the fuel level is maintained at or above normal level. The present invention is aimed at maintaining the proper fuel level in this type of carburetor. l

The use of means to enrich the mixture on throttle opening creates, in turn, another problem to be overcome, and that is engine stalling caused by an excessively rich mixture due to the manifold being excessively wet with fuel when the throttle is closed. To solve this problem, it is necessary to retard the closing rate of the throttle. Devices for this purpose are well known in the art, but these devices are usually separately constructed for attachment exterior of the carburetor, andhave no other I function besides that of retarding closing movement)";

According to this invention, the device for retarding throttle closing has a dual purpose to enrich the mixture, For this purpose, a separate cham on throttle opening. her is formed in the fuel bowl and suppliedwith-fuel from the constant level fuel chamber. This separate chamber encloses aseparate floati A resilient connection between the floatand the throttle is arranged to impose a resistance'to throttle closing so as to act as a throttle closing rate retarder; Incidental to this operation, the separate float displacement is increasedyand consequently the fuel level raised in the constant level fuel chamber and in the accelerating well to a level above the air bleed in the accelerating well. When the throttle is subsequently opened, the flow offuel from the main nozzle. is substantially instantaneous becauseof the combined lifting effect on. the nozzle and air bleedand the decrease.

in distance between the fuel level in the bowl andthe tip of the nozzle. Any noticeable transition point be-q tween the operation of the carburetor on the .idle ports" 7 Patented May 28, 1957 alone to operation" on1themain fuel nozzle is overcome,

and operation of the engine is smoothed by elimination of the flat spot which 'often occurs at this transition point, 'Thiscan be attributed in part to the presence of solid fuel in the nozzle, and in part to the increase in fuel level to decrease the amount of lift from the raised level to the tip of the nozzle during'the corresponding lower suction obtained in the venturi at low enginespeed.

' Other objects and advantages of this invention will become apparent as theidescription proceeds.

By way of example, the drawings illustrate:

Fig. 1 is a vertical section through a carburetor constructed according to the present invention showing the position of the parts with the throttle closed; and

Fig. 2 is a vertical section through the carburetor showing'the position of the parts with the throttle open.

Fig.3 is a vertical fragmentary section illustrating a modification of the invention.

For the purposes of illustration, the invention has been 7 shown in an engine-aspirated type of carburetor provided with a constantlevel fuel chamber communicating directly' through the usual metering device with the fuel nozzle by wayof a vertically arranged accelerating well having an air bleed. The constant level fuel chamber may be the usual fuel bowl with a float controlled needle valve in the fuel supply.

Referring now to the drawings,

Fig. 1 shows a carburetor provided with an air horn 12, a nozzle body 10, and a throttle body 13. Formed integral with the nozzle body is a float chamber 11 closed by afloat chamber cover 1.4 having a dust cap 15. A mixture conduit 16 forms a passage extending from the air horn 12 to and through the throttle body 13. Within the air horn 12 is a choke valve ls moun'ted on a choke valve shaft 19, which may be controlled manually or automatically in a well known manner.

Throttle body-'13 mounts a shaft 20 for throttle valve.

21. Nozzle body 10 contains a pair of venturis 23 and 24 inounted in superposed relationand cast-integral there-f with. A fuel nozzle 26 is arranged within the throat of the upper venturi 24 and communicates with an'accele'ratinglwell 28 which is, in turn, connected 'by passage 29 j and fuelmeteringorifice 30 with fuel bowl 11. A vent tube 31 having a plurality of vent openings therein along itsf'length projects downwardly within the accelerating well 28 and is provided with an orifice open to the pressuresiflwithin mixture conduit 16 above the main fuel nozzle'but beneath the choke valve 18.

Also connected with fuel passage 29 is an idle tube 34 within a well 35 which connects byway of passage 37 with idle vent port 38 and" idle fuel nozzle 39. Fuel nozzle 39 is-provided with an adjustable mixture control in the form of a threaded needle valve 40.

As shown in this figure, throttle shaft 20 is connected byalever 42 and-me'chanism43'with a'countershaftj44 within the chamber above the fuel bowl 11 and under the dust cap 15. Fix-edly mounted on the counters-heft 44 is a finger 46 which protrudes'beneath a bar 47 mounting a metering rod 48. This metering rod may be controlled by either suction posterior the throttle or by rotation of the shaft 44 duringkopening movement of the. throttle 2 1,

"all in a well known manner;

Within-the .fuel bowl 11 are a pair of independently structure is regarded as more or less conventional in the art, and is not, therefore, illustrated in detail.

The mechanism for retarding the closing of the throttle and thereby varying the fuel level within the float bowl with throttle position is operated from the countershaft 44 which moves with the throttle 21 because of its direct interconnection above described. Adjustably secured on the countershaft 44 by a set screw 60 is a cam ha ving a nose portion 61 engaging a head 66 on a pin 62. This pin is slidably mounted in a suitable aperture in float bowl cover 14, and is surrounded by a spring 65 received within a well concentric with the aperture for mounting the pin. The spring 65 engages under a head 66 on pin 62, constantly urging pin 62 upwardly. Within the float bowl 11 the pin is formed with a stepped shoulder 68 engaging a washer 69. A spring 70 surrounds the pin 62 and is interposed between the washer 69 and an apertured ear 72 formed integrally with the float-supporting arm 51. In this particular structure the spring 65 is stronger than the spring 70, but both springs will urge head 66 of the pin 62 upwardly to resist clockwise rotation of the cam 61 and countershaft 44, and thereby retard the rate of throttle closing movement. In the structure shown, spring 65 bears directly upon the float bowl cover 14, whereas the spring 70 is compressed by downward movement of the pin 62 between the washer 69 and the car 72, thereby exerting pressure tending to submerge the float 50.

In operation, with the throttle valve closed, as shown in Fig. l, a cam 61 forces the pin 62 downwardly to compress the spring 70. The elfect produced by the spring 70 will be similar to increasing the weight of the float-supporting arms 51, which, in turn, will tend to submerge the float 50. Consequently, it will require a greater fluid displacement by the float 50 in order to overcome the weight imposed on the float-supporting arm 51 by the resistance of spring 70. The result will be that the fluid level within the float bowl 11 will rise to a position shown by the dotted line L-l shown in Fig. 1.

Since, with the throttle 21 closed, no fuel will be flowing from the main nozzle 26, the level within the accelerating well 28 will correspond with that in the float bowl 11. At the level shown by the line L-1, the ports within the vent tube 31 will be submerged. Consequently, any drop in pressure adjacent the nozzle 26 will immediately act to raise the fuel from the level L-1 to the tip of the nozzle 26, and the siphoning action produced by this drop in pressure will act exclusively on the fuel and without interference from the bleed port 31, which has a tendency to decrease that suction elfect. When the throttle is opened as shown in Fig. 2, solid fuel will be immediately available at the main nozzle 26 to properly enrich the fuel mixture as the throttle opens to cover the transition point which always occurs between the operation of the carburetor on the idle ports and operation of the carburetor by function of the main fuel nozzle.

In Fig. 2, after the throttle is partly open, and the pressure of spring 70 has been removed from the float arm 51, an elfect will be produced similar to increasing the buoyancy of the float 50. Its displacement is decreased by an increase in effective buoyancy to lower the fuel level within the float bowl from the line L-1 to the line L-2, thereby decreasing the mixture richness from the main nozzle 26 by producing a fuel level which is below the bleed openings within the vent tube 31, so that the fuel within-the accelerating well becomes emulsified by the mixing with air from the vent 31 to produce a much leaner mixture.

The primary object of the invention above described is to produce a mechanical device which will retard throttle closing movement. The action of this structure to fulfill this object will now be described.

-Referring to Fig. 2, it is apparent that, in the closing movement of the throttle, cam nose 61 slidably engages the head 66 of pin 62. The contour of the cam nose 61 is such that rotation of the cam from its position in Fig. 2 to its position in Fig. 1 produces a longitudinal displacement of the pin, compressing the springs 65 and 76. Thus, rotation of the cam nose 61 is mechanically resisted by compression of the springs 65 and 70, and frictionally resisted by the sliding action of the cam on the head of the pin 66. As the springs are compressed, the mechanical resistance of pin 62 increases, as does also the frictional resistance. Both of these resistances produce a damping action on the movement of the throttle 21 in the closing direction.

A secondary effect from the mechanical displacement of pin 62 is the compression of the spring 70, which, as above described, in elfect increases the displacement of the floats 50 to increase the fuel level from the line L-2 to the line L-l, so that downward movement of the pin 62 produces added resistance by increasing the reacting force exerted by the floats 50 in a manner similar to a servo-mechanism. This effect further compresses spring 70, increasing the resistance of the pin 62 to mechanical displacement by the cam nose 61, and increases the frictional resistance between the cam nose 61 and the head 66, so that, as the throttle valve closes, all of the forces tending to resist this movement increase, providing a variable rate of damping action on throttle closing movement.

Referring to Fig. 3, a modification has been shown having elements corresponding with those above described for performing the same function. In this view elements corresponding to those shown in the prior figures have been given like reference characters with the prefix l. The fuel bowl 111 has a dust cover 114 enclosing a cam 161 which is secured to a countershaft such as 44 shown in Fig. l. The nose portion 161 of the cam engages a head 166 on a pin 162. This pin is slidably mounted in a suitable aperture in the float bowl cover 114 and is surrounded by a spring 165 received within a well concentric with the aperture for mounting the pin. The spring 165 engages under a head 166 on the pin 162 and constantly urges the pin 162 upwardly into frictional engagement with the nose of the cam 161 during throttle closing movement. Within the float bowl 111, the pin is formed with a stepped shoulder168 in abutting relation with a washer 169. Spring 170 surrounds the pin 162 and is interposed between the washer 169 and an apertured ear 172 formed integral with a float 150. As shown in this figure, the float structure is annular, and the pin 162 projects through the center of buoyancy of the float and through the support 172 arranged slightly below the center of buoyancy, so that there will be no tendency of the float to cant with respect to the pin 162.

The spring is stronger than the spring 170, but both springs will urge the head 166 of the pin 162 up wardly to resist clockwise rotation of the cam 161 and its countershaft, thereby retarding the rate of throttle closing movement. The action of the pin 162 on throttle closing compresses the spring 170 between the washer 169 and the car 172, and thereby exerts pressure tending to submerge the float 150.

The operation of the structure in Fig. 3 is substantially identical with that above described. Closing throttle movement will submerge the float 150 to raise the fuel level in the auxiliary chamber, and the constant level fuel chamber communicating therewith, from L-2 to L4. This will produce the same effect on throttle closing and on mixture as described in the operation of Figs. 1 and 2. It will be understood that this modification is used in the fuel bowl of a carburetor having the usual independent float for controlling the fuel level.

It is contemplated that this invention may be practiced in many different ways obvious to those skilled in the art.

lam.

The invention is not limited by the specific illustration here, but only by the scope of the appended claims.

I claim:

1. In a carburetor, a mixture conduit having a throttle .and a main fuel nozzle, 21 fuel bowl for said carburetor to supply fuel to said main nozzle, an accelerating well between said fuel bowl and said main nozzle and supplied with fuel from said bowl, an air bleed for said accelerating well having a vent tube extending into said well with an opening normally above the fuel level in said well, a throttle operated means for submerging said vent opening by increasing the fuel level in said fuel bowl during throttle closing movement.

2. In a carburetor, the combination of a mixture conduit having a main fuel nozzle and a throttle valve, a fuel bowl for supplying fuel to said main nozzle, an accelerating well in said main fuel nozzle system having an air bleed and a vent tube extending into said well with an opening normally submerged in the well when said fuel nozzle is not in operation, and means operated by said throttle for lowering the fuel level in said bowl on throttle opening to expose said vent opening.

3. In a carburetor, a mixture conduit having a main fuel nozzle and a throttle valve, a fuel bowl for supplying fuel to said main nozzle, float mechanism in said fuel bowl, and a yielding connection between said throttle valve and said float mechanism including means for compressing said yieldable connection on throttle closing.

4. In a carburetor, the combination of a mixture conduit having a throttle, spring means for closing said throttle, a constant level fuel chamber for supplying fuel to said mixture conduit, a main fuel nozzle extending from said chamber and discharging into a portion of said conduit above the normal fuel level in said chamber, a float in said chamber, and mechanism interconnecting said throttle and said float constructed and arranged to depress said float upon closing of said throttle so as to retard said throttle closing and raise the fuel level in said chamber and said main fuel nozzle.

5. In a carburetor, the combination of a mixture con duit having a throttle, spring means for closing said throttle, a constant level fuel chamber for supplying fuel to said mixture conduit, a metering orifice in said chamber, main and idling fuel supply passages extending from said metering orifice into said conduit, respectively, anterior and posterior to the edge of said throttle valve when closed, said main fuel nozzle discharging into a portion of said conduit above the normal fuel level in said chamber, a float in said chamber, and mechanism interconnecting said throttle and said float constructed and arranged to depress said float as said throttle is closed for raising the fuel level in said chamber and said main fuel passage.

6. In a carburetor, a mixture conduit having a throttle and a main fuel nozzle, a fuel bowl for said carburetor to supply fuel to said main nozzle, an accelerating well between said fuel bowl and said main nozzle and supplied with fuel from said bowl, an air bleed for said accelerating well having a vent tube extending into said well with an opening normally above the fuel level in said well, and a throttle operated means including a float in said bowl for submerging said vent opening by increasing the fuel level in said fuel bowl during throttle closing movement.

7. In a carburetor, the combination of a mixture conduit having a throttle, spring means for closing said throttle, and a device actuated by said throttle for mechanically and frictionally opposing throttle closing movements comprising a cam frictionally engaging a push rod, and means including a float and a compression spring coacting therewith for variably resisting movement of said push rod.

8. In a carburetor, the combination of a mixture conduit having a throttle, spring means for closing said throttle, and a device actuated by said throttle for mechanically and frictionally opposing throttle closing movements comprising a cam frictionally engaging a push rod, and means for variably resisting movement of said push rod, said means comprising a float mechanism, and a spring interposed between said rod and float mechanism.

9. In a carburetor, a mixture conduit having a throttle and a main fuel nozzle, a fuel bowl for said carburetor to supply fuel to said main nozzle, an accelerating well between said fuel bowl and said main nozzle and supplied with fuel from said bowl, an air bleed for said accelerating well having a vent tube extending into said well with an opening normally above the fuel level in said well, a throttle operated means including a float in said bowl for submerging said vent opening by increasing the fuel level in said fuel bowl during throttle closing movement, and means coacting with said float to retard closing movement of said throttle.

References Cited in the file of this patent UNITED STATES PATENTS 1,536,910 Norton May 5, 1925 1,872,555 Ball et al Aug. 16, 1932 2,633,342 Baker Mar. 31, 1953 2,703,705 Boller Mar. 8, 1955

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