US1948999A - Carburetor - Google Patents

Description

Feb. 27 1934. B, w. WESTCOTT 'CARBURETOR FiLedSept. 22' 1931 INVENTOR www w mm,

Patented Feb. '27, 1934 CABBURETOR m ma w. Westcott, Detroit,= we... aim to Zenith-Detroit corporation, Detroit, men,

Michigan a corporation of Application September 22, 1931 Serial No. 564,288

6 0mm. (or. 2611-34;

The present invention relates broadly to the art of charge forming devices of the type usually characterized as carburetors, and more particularly to carburetors such as utilized forsupplying a combustible mixture to an internal com bustion engine. I

For purposes of the present invention, carburetors may be divided broadly into two classes,v these being the so-called up draft carburetors and down draft carburetors. With both types of carburetors-it has heretofore been proposed to provide means, in the form of a pressure controlled pump, for changing the mixture characteristics under different operating conditions of the motor.

It is customary to provide carburetorsof both types with a throttle adapted to be either manually or automatically controlled and effective for'regulating the quantity of the mixture which passes from the carburetor to the engine. It is well known that for best results, the mixture ratio of fuel and air for purposes of maximum power and maximum economy, is notconstant with varying load conditions. As the load, which in turn represents the work being done, varies,

the quantity of the mixture must be varied as well as the quality or richness thereof. Thus, a carburetor initially adjusted to insure maximum fuel economy throughout the normal range of operation, has imposed upon it a limitation precluding the development of maximum power by the engine connected thereto. On the contrary, if the carburetor is initially so set as to give a mixture insuring the development of maximum power, there is an appreciable loss of efficiency in fuel consumption throughout the major period of engine operation. v

These contrary conditions have been hereto fore reconciledby the provision of a pump adapt-= ed to supply an increased amount of fuel under such conditions ,of engine operation as to require an increase in the richness of the mixture. One well known type of pump is controlled entirely by the pressure conditions existing on the engine side of the throttle, the pump being so connected with the intake manifold that with high vacuum,

i. e., low absolute pressure conditions in the manifold on the engine side of the throttle, the

pump will be held in inoperative position, while with a decrease in vacuum, i. e., an increase in the absolute pressure, the pump will become operative for insuring an added fuel quantity.

with both of the foregoing types of carburetors, such a pump, usually referred to as an I, accelerating pump, has been characterized by the factthat stopping of the motor; which represents the greatest possible decrease in the vacuum, or increase in the absolute pressure within the manifold, necessarily results in operation of the pump and the supply of an additional quantity of fuel at a time when no fuel is required by the engine With an up draft carburetor, this is not particularly objectionable for the reason that the excess fuel discharged through the nozzle system into the venturi flows backwardly and drains from the-carburetor. tion therefore is with respect to loss of fuel. With a down draft carburetor, however, the fuel supplied uponstopping of the motor flows into the as Its principal objecmanifold. This fuel, depending upon the manifold construction, is either permitted to collect within the manifold or run into the motor. In either case, there is not only a loss of fuel, but

an objectionable loading of themanlfoldor mo- 7 tor with raw gasoline.

The present invention has for one of its ob jects the provision of a carburetor including an accelerating pump of such construction that operation .of the pump upon stopping of the motor is prevented. While especially adaptable to down draft carburetors, it is applicable as well to up draft carburetors where fuel saving is a factor. a I

In the accompanying drawing I have shown, more orless diagrammatically, apreferred embodiment of my-invention. In the drawing- Figure 1 is a view partly in section and partly in side elevation illustrating a portion of a down draft carburetor with the throttle in closed positi'on and the accelerating pump held against operation; and 1 Figure? is a view similar to Figure 1, illustrating the normal position of the parts with the throttle in open position and the pump free to perform its intended function. I In my co-pending application Serial No. 514,-

163, filed February 7, 1931,. which matured to" Patent 1,912,468 granted Jan. 6, 1933, there is illustrated indetail a complete carburetor structure including an accelerating pump of the general character herein disclosed, but without any means for rendering such pp inoperative upon stopping of the motor. 1

In accordance with the present invention, there may be provided a carburetor of suitable construction including an air intake section 2 including a ventm'i 3 and terminat in a flange 4 adapted to be secured to the intake manifold (not shown). The fuel quantity delivered to the engine supplied by the carburetor, is controlled by a throttle 5 of any desired construction adapted to be operated in known manner and to the shaft 6 of which is secured a lever 7.

Disposed laterally of the air intake is a fuel reservoir 8, preferably of the constant level type having in its lower portion a check valve 9 within a valve casing 10 having a lower seat 11 and an upper seat 12. With the valve 9 in position against the lower seat 11, as illustrated in the drawing, fuel may flow freely through the opening 14 in the valve casing and thence through the port 15 around the periphery of the valve into a passageway 16 leading to an accelerating cylinder 1'7.

Mounted within the accelerating cylinder 1'7 is a plunger 18 connected through the medium of a ball and socket connection 19 to a rod 20. This rod'in turn has a similar connection 21 at its upper end to an economizer and accelerating piston 22. The upper surface of the piston may be exposed, by means of a suitable series of passages and ports 23 to the manifold at a position intermediate the throttle and the motor, whereby the piston is at all times subjected to such pressure conditions. In such cases, with the throttle partly opened, and the motor to which the carburetor is connected functioning, there will be a relatively high vacuum intermediate the throttle and the engine. This vacuum will be transmitted by way of passages 23 to the piston 22, and will be effective for holding the piston in the-position illustrated in Figure .1 against the action of a spring as.

Should the throttle be suddenly opened, the absolute pressure intermediate the throttle and the engine will increase to such. an extent that it will not be effective for holding the piston 22 in its upper position against the action of the spring 24. At such time, the spring will depress the plunger 18 into the position illustrated in Figure 2. In this position it will come into engagement with the stem 25 of an economizer valve 26. This economizer valve is normally carried by a valve casing 27, being guided at its lower end by a spider 28. Intermediate the spider and-the valve is a spring 29 effective under normal conditions for maintaning the valve 26 against its seat. When the valve stem 25 is engaged by the plunger 18, the pressure of the spring 29 will be overcome, and the valve. 26 moved away from its seat. Such downward movement of the plunger will also be effective through the passage 16 for closing the check. valve 9=against its upper seat 12 in the valve casing 10, thus cutting off communication between the float chamber 8 and the cylinder 1'? and thereby preventing any fuel charges within the cylinder 1'7 from being forced backwardly into the float chamber. The fuelwithin the cylinder 17 will thus be forced past the economizer valve 26 into a suitable nozzle 30 discharging within the venturi 3 below an air deflector 30'. A sudden descent of the plunger18 is thus effective for delivering an accelerating or enrichening charge to the venturi at such times as a sudden demand for more fuel, represented by the quick opening of the throttle, is made by the motor. If the condition of increased fuel demand continues, the plunger 18 will remain in its lower position, and upon the release of accumulated.

fuel from the cylinder l'l, the check valve 9 will again drop downwardly by gravity .and establish a fuel flow directly from the float chamber 8 to the nozzle 30 by way of check valve 9, passage 16,

cylinder 17, and economizer valve 26.

It may be assumed that the condition just decable to carburetors of other types.

scribed exists atsuch times as the motor is running at high speed, or under heavy loads. Should the speed be decreased by partially closing the throttle, the absolute pressure in the manifold intermediate the throttle and the engine will decrease, and the plunger 18 will again be raised, thus permitting the economizer valve to close and thus re-establish normal fuel flow conditions.

Should, however, the throttle be completely closed, and the motor stopped, the absolute pressure within the manifold intermediate the throttle and the engine will increase to a maximum, and unless special provision is made, the plunger will descend and thus force into the venturi all of the accumulated fuel within the cylinder 17. As before stated, if the carburetor is of the up draft type, the fuel will drain downwardly and flow. out of the carburetor, but if it is of the down draft type, the fuel will be accumulated either in the manifold or in the motor itself. In order to preclude the possibility of such an operation, I provide a cam rod 31 adapted to be engaged at its lower end by the lever 7 when the throttle is moved to its closed position as illustrated in Figure 1. This engagement'will raise the cam rod against the action of a spring 32 and thus cause an inclined surface 33 thereon to move a stop pin 34 inwardly into locking engagement below the piston 22, thus precluding descent of the piston and plunger at such times. When the throttle is opened awayfrom the cam rod, as illustrated in Figure 2, the spring 32 will move the cam rod downwardly, thus releasing the lock pin 34 and permitting its spring 35 to move the lock pin outwardly into the position illustrated in Figure 2 and thus permit normal operation of the plunger assembly.

From the'foregoing description it will be apparent that I have provided means effective upon complete or substantially complete closing of the throttle for rendering the accelerating plunger or pump inoperative, the construction being such that upon opening the throttle as required for operation of the engine, the complete assembly becomes automatically operable. In this manner the supplying of an accelerating or excess charge of fuel upon stopping of the motor, is prevented.

The advantages of the present invention arise from the provision of a carburetor structure including accelerating means responsive to pressure conditions in combination with means effective at the will of the operator for rendering the same inoperative.

While I have herein illustrated the invention as applied to a carburetor of the down draft type, it will be apparent that it is equally appli- It will further be apparent that changes in the construction and operation of the parts may be made without departing either from the spirit of my invention or the scope of my broader claims.

I claim:

1. In a carburetor including a throttle, a fuel pump responsive to pressure conditions on one side of the throttle for effecting an increase in fuel flow to the carburetor, and throttle operated means for rendering said fuel pump inoperative, said means being so constructed and arranged as to be capable of rendering said fuel pump inoperative only when the pump is in predetermined position.

2. In combination, a motor, a carburetor therefor including a throttle, a fuel pump responsive to pressure conditions on one side of the throttle 1,948,699 foreflecting an increase in fuel flow to the carburetor, and means operable upon closing of the throttle and stopping of the motor for rendering said fuel pump inoperative.

3. In a carburetor including a throttle, a fuel pump responsive to pressure conditions on one side of the throttle for eifecting an increase in fuel flow to the carburetor, and-locking means for said fuel pump controlled by the position of the throttle, said locking means being constructed to assume operative and inoperative positions with respect to the fuel pump.

4. In a carburetor including a throttle; a fuel pump responsive to pressure conditions on one side of the throttle for increasing the fuel flow to the carburetor when the absolute pressure on such side of the throttle increases. and means for rendering said fuel pump inoperative, as the 3 throttle is moved into a predetermined position and the absolute pressure on such side of the throttle increases to a maximum.

5. In a carburetor including a throttle, a fuel pump responsive to pressure conditions on one side of the throttle for increasing the fuel flow to the carburetor when the absolute pressure on such side of the throttle increases; and means for rendering said fuel pump inoperative, said means being. rendered operative upon movement of the throttle to its closed position.

6. In a carburetor including a throttle, a fuel pump responsive to pressure conditions on one side of the throttle fuel flow to the carburetor, and throttle operated means adapted to engage the fuel pump for rendering the same inoperative.-

' BRAYTQNW. WESTCO'I'I.

for effecting an increase in

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