US2033220A - Charge forming device - Google Patents

Description

Patented Mar. 10, 1936 UNITED STATES PATENT CHARGE FORNEING DEVICE Application September 21, 1933, Serial No. 690,336

6 Claims.

This invention relates to charge forming devices for internal combustion engines; In the drawing the invention is illustrated as embodied in that type of charge forming device which comprises a plurality of primary mixing chambers, each of which is adapted to deliver a primary mixture of fuel and air to one of a plurality of secondary mixing chambers located adjacent the engine intake ports and to which additional air may be supplied for mixture with the primary mixture. An example of this type of charge forming device is shown in the patent of Fred E. Aseltine, et. al., Patent No. 1,937,938 issued December 5, 1933. It will be understood, however, that the present invention is not limited in its use to this particular type of'charge forming device but is applicable to charge forming devices of conventional type as well;

The primary object of the present invention is to provide means for supplying additional fuel to the mixture passages when the engine is'cold to facilitate starting of the engine'to progressively decrease the amount of such fuel as' the'engine warms up and to render such fuelsupply means inoperative after the warm-up period when the engine reaches a predetermined temperature.

A further object is to provide-a fuel supply means functioning in the manner described and so constructed as to supply a small quantity of air only after the engine has heated'up andthe device has ceased to function as a fuel supply means.

These objects are accomplished by the provision of an additional fuelsupply passage which is adapted to deliver fuel to each of theprimary mixture passages at a point immediately in advance of the throttle which controls the flow therethrough and a valve is provided which controls the flow of fuel to these mixture passages, the valve being controlled by a thermostat. The valve is also adapted to control passages which admit air to the additional fuel supply passages and are so arranged that when the valve is positioned to fully open the fuel passages, the air passages are. closed. As the engine warms up, the thermostat causes the valve to progressively close the fuel passages and to simultaneously open the airfpassagesso that when the fuel passages are fully closed the air passages are fully open.

Further objectsand advantages of the present invention will be apparent fromthefollowing description,: reference being hadto. the accompanyingxdrzlwing wherein a preferred embodimentnfrthe'present inventionis clearly-show In the drawing:

Fig. 1 is a vertical, longitudinal section through a charge forming device embodying the present invention.

Fig. 2 is an enlarged fragmentary detailed 5 sectional view showing the construction of the fuel and air passages and the valve controlling them.

Fig. 3 is a sectional view on line 3-3 of Fig. 2.

Fig. 4 is a fragmentary elevation showing the 10 fuel valve and. the thermostat which operates the valve. Figs. 5, 6 and 7 are fragmentary sectional views showing the fuel control valve in different positions.

It is deemedunnecessary in this application to illustrate the manifold which forms a part of the charge forming device since the invention to which this application relates is confined entirely to the carburetor unit which is associated with said manifold.

The carburetor unit as shown in Fig. 1 comprises a main housing 20 having a flange 22 adapted to be connected by machine screws to a corresponding flange on the manifold. An air inlet coupling-24 is secured in position in registry with an opening in the wall of the housing 20 in any suitable way. A casting 26 having certain fuel passages and dash pot chambers formed therein is secured by screws to the lower wall of the housing 20 and a sheet metal fuel bowl 28 is held tight against, a shoulder 30 formed on the housing 20 by a screw 32 which is screwed into a depending portion of the casting 26. Fuel is conducted from a main source of supply to the fuel bowl through a conduit (not shown) and the flow of fuel to the bowl is controlled by a float (not shown) in the usual manner to maintain a substantially constant level of fuel therein.

Fuel flows from the bowl 28 to a plurality of primary fuel nozzles 34, one of which is located in each of these primary mixing chambers 36, the construction of which is the same as disclosed in the earlier application. The fuel conduit between the fuel bowl and the nozzles comprises a vertical fuel passage (not shown) which communicates at its upper end with a horizontal channel 38 which communicates with each of the nozzles 36.

Fuel is lifted from the fuel bowl through the 50 above described fuel passages and nozzles to the mixing chambers 36 by the suction maintained therein. To prevent a reverse flow of fuel upon a reduction of suction which occurs upon closing movements of the throttle or upon increase of load, a check valve (not shown) is provided to prevent a return flow from the horizontal channel 38 to the fuel bowl.

Each primary fuel nozzle is provided with a main fuel outlet at the top of the nozzle and a secondary fuel outlet comprising two orifices 40 and 42 in the vertical wall of the nozzle near the bottom of the mixing chamber. At relatively high speeds the mixing chamber suction causes a flow from the top of the nozzle and also from the orifices 40 and 42, but at idling and low speed operation under load, the suction is suflicient to lift fuel only to some point between the top of the nozzle and orifices 40 and 42, fuel then flowing through these orifices by the action of gravity. Each nozzle is provided with a restricted fuel metering orifice 44.

The primary mixing chambers comprise the enlarged anterior ends of the primary mixture passages 60, which are parallel to each other and close together, as indicated in Fig. 3. When the carburetor is attached to the manifold these passages register with conduits which convey the primary mixture to secondary mixing chambers formed in the manifold. The mixing chambers 36 are separated from the mixture passages 60 by restrictions 62 and the primary throttle valve 64 is positioned immediately posterior to these restrictions, said valve extending across all of the mixture passages 60 and regulating the fiow therethrough.

Substantially all the air entering the carburetor fiows through the coupling 24 controlled by a main air valve 66 normally held against a seat 68 by a spring 70 received between the valve and a flange I2 projecting from a sleeve I4 slidably mounted on a stationary guide sleeve I6 fixed in the housing 20 and serving as a guide for the stem I8 to which the air valve is secured. When it is desired to choke the carburetor to facilitate starting, the flange I2 is adapted to be lifted by means not shown herein but fully described in the earlier application referred to, until the upper end of the sleeve I4 engages the air valve 66 to hold it closed. During the choking operation sufiicient air to carry fuel from the nozzles to the engine is admitted through a slot 80 formed in the plate 82 secured to the housing as shown in Fig. 1.

The valve 66 admits air to a main air chamber 84 from which air flows to the primary mixture passages through an opening 86 in the floor of said chamber and to the manifold through a passage 88 which connects with the manifold inlet. A manually operable valve 90 secured to a shaft 92 journalled in the housing 20 controls the flow of air through the passage 88, said valve 90 being operated from the primary throttle 64 by means of connections which are not illustrated herein, but which connections are shown in said Patent No. 1,937,938. In order to better understand the operation of the device in general it may be said that the valve 90 is operable by the throttle 64 through the medium of a lost motion connection so that the valve 90 cannot begin to open until the throttle 64 has opened to some extent, generally to a position to cause the engine to operate at a speed corresponding to a vehicular speed of approximately 20 miles per hour on the level. As the valve 98 beings to move, the valve and throttle 64 move together until both reach fully open position.

Upon any increase of suction in the chamber 84 which follows an opening of the throttle to increase the speed or a change in the degree of load, the valve 66 is opened to admit additional air and to increase the quantity of mixture supplied to the engine. The opening of the valve is retarded to some extent, however, to prevent admission of sufiicient air during the acceleration period to lean the mixture. For this purpose and also to prevent fluttering of the valve, a dash pot is provided which comprises a cylinder I formed in the casting 26 and a piston I02 secured to the lower end of the valve stem I8, is slidably received in the cylinder. Liquid fuel is admitted to the cylinder and on downward movement of the piston I02 such fuel is forced from the cylinder by leakage around the piston whereby the movement of the piston is considerably retarded.

In addition to the choke mechanism previously referred to which is provided to aid in starting the engine, it has been found desirable to provide means for supplying additional fuel when the engine is to be started when cold and to provide means for preventing'this supply of additional fuel from taking place when the engine is to be started when hot. It has also been found to be desirable to supply such fuel on the high suction side of the throttle 64. To this end a fuel passage H0 is formed at a depending portion of the casting 26 and such passage communicates at its upper end with a cross-channel II2 which extends aeross all of the several mixture passages 60, as shown in Fig. 3. Fuel passages I I4 extend upwardly from the cross-channel H2 and connect with a cylindrical bore I I6 in the wall of the housing 20 immediately posterior to the throttle valve 64. Received in the bore is a plug valve II8. which has certain passages extending through the valve and on the surface thereof which communicate with the passages H4 and with passages I 20 which extend from the bore I I6 to mixture passages 60.

The valve H8 has three passages I 22 which extend through the valve and adjacent one end of each of the passages I22 are two cut-away channels cut in the exterior surface of the valve and numbered I24 and I26 respectively. Also at the other end of passages I 22 are external passages I28. Communicating with the bore in which the valve is received are also three horizontal passages I 30, which are in the wall of the housing 20 and connecting with the three passagesI30 are three passages I32 which communicate at their lower ends with the atmosphere. The structure of the valve is such that when it occupies the position shown in Fig. 5, the channels I22 communicate with the passages I I4 and with the three fuel passages I20 which connect with the mixture passages so that fuel will flow from the channel II2 through the passages II4, I22 and I20 into the mixture passages 60. With the valve in this position, the passages I30 are completely closed. The valve is adapted to be moved in counterclockwise direction in Fig. by means hereinafter described and as the valve is so moved, the passages I22 are gradually moved out of registry with the passages I I4 and during this movement the passages I26 which are formed in the exterior surface of the valve are gradually brought into registry with the passages I30 so that air which is admitted through the passages I30 can flow into the mixture passages through the passages I I4 to dilute the fuel which is drawn through the passages I22, the passages I24 being in registry with passages I22, and passages I28 connecting passages I22 and I at this position of the valve as shown in Fig. 6. Fuel and air are both admitted with the valve in this position. As

the valve continues its counterclockwise motion to the Fig. 7 position, the passages I20 are completely closed. Air entering passages I30 can leak around to break the suction on the fuel in the passage llfl so that a small quantity of air only is admitted with the parts in this position.

In order to move the valve as described, the valve is provided with an arm M0 secured to one end of said valve outside the housing and a link I42 which is pivotally connected to the end of said arm connects at its opposite end with a bimetallic thermostat l 44, one end of which is suitably secured at any desirable point on the carburetor housing. When the engine is cold the thermostat is contracted and the valve occupies the position shown in Fig. 2, but as the engine heats up when it starts to run under its own power, the expansion of the thermostat through the medium of the connections described, rocks the valve in a clockwise direction in Fig. 4 to accomplish the results previously described.

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

What is claimed is as follows:

1. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air to said mixture passage, a fuel passage for supplying additional fuel to the mixture passage, a valve for controlling the flow of fuel therethrough, said valve having a passage therthrough normally registering with the fuel passage, external passages of smaller size communicating with the passage through the valve and adapted to be brought into registry with the fuel passage as the passage through the valve moves out of registry with said fuel passage during movement of the valve, and means for moving said valve.

2. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air to said mixture passage, a fuel passage for supplying additional fuel to the mixture passage, a valve for controlling the fiow of fuel therethrough, said valve having a passage therethrough normally registering with the fuel passage, external passages of smaller size communicating with the passage through the valve and adapted to be brought into registry with the fuel passage as the passage through the valve moves out of registry with said fuel passages during movement of the valve, and thermally responsive means for moving said valve.

3. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air to said mixture passage, a fuel passage for supplying additional fuel to the mixture passage, a valve for controlling the flow of fuel therethrough, said valve having a passage therethrough normally registering with the fuel passage, external passages controlling the flow of fuel therethrough, said valve having a passage therethrough normally registering with the fuel passage, external passages of smaller size communicating with the passage through the valve and adapted to be brought into registry with the fuel passage as the passage through the valve moves out of registry with said fuel passage during movement of the valve, an air passage also controlled by said valve, another external passage communicating with the passages through the valve and adapted to be brought into communication with the air passage as the valve is moved and means for moving said valve 5. A charge forming device for internal combustion engines comprising a mixture passage, means for supplying fuel and air to said mixture passage, a fuel passage for supplying additional fuel to the mixture passage, a valve for controlling the flow of fuel therethrough, said valve having a passage therethrough normally registering with the fuel passage, external passages of smaller size communicating with the passage through the valve and adapted to be brought into registry with the fuel passage as the passage through the valve moves out of registry with said fuel passage during movement of the valve, an air passage also controlled by said valve, another external passage communicating with the passage through the valve and adapted to be brought into communication with the air passage as the valve is moved and thermally responsive means for moving said valve.

6. A charge forming device for internal combustion engines comprising a plurality of primary mixture passages adapted to deliver a primary mixture of fuel and air to a plurality of secondary mixing chambers, means for supplying fuel and air to said primary mixture passages, means for supplying additional air to the secondary mixing chambers, means for supplying additional fuel to all of the primary mixture passages to facilitate starting of the engine, said means comprising a fuel passage, a horizontal channel connecting therewith, a plurality of passages each of which connects the horizontal channel with one of the primary mixture passages, a valve for controlling the flow of fuel through all of the last named passages and thermally responsive means for operating said valve.

FRED E. ASELTINE.

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