US2775435A - Carburetor accelerating pump with gas vent - Google Patents

Description

F. A. KOMMER CARBURETOR ACCELERATING PUMP WITH GAS VENT Filed Jan. 24, 1952 INVENTR.

FRED A. KOMMER F 10,4. W Z,

ATTORNEY CARBURETOR ACCELERATING PUMP WITH GAS VENT Fred A. Kommer, St. Louis, Mo., assignor, by mesne assignments, to ACE Industries, Incorporated, New York, N. Y., a corporation of New Jersey Application January 24, 1952, Serial No. 267,942

7 Claims. (Cl. 261-34) This invention relates to carburetors for internal combustion engines and, more particularly, to improvements in a novel type of accelerating pump such as'is shown in aco-pending application of John S. Carrey, Serial No. 117,772, filed September 26, 1949, entitled Carburetor, now Patent No. 2,619,533 of November 25,

Inthe prior device, the accelerating pump was pro- ,lvided with a constantly open inlet to the pump chamher. This Was for the purpose of permitting the fuel from thefuel bowl to fill the pumping chamber, and,

incidentally, to vent from the chamber any accumulation "of vapors or gases which might tend to produce a vapor'1ock in the accelerating pump. This arrangement was found not completely satisfactory for the 'latter lpurpose, since the static head of liquid pressure prevented the gases from escaping. The present disclosure "relates to a modification of the pump which provides adequatetand suitable venting and prevents vapor lock.

The invention has been illustrated as applied to a diaphragm type of pump, but it is obvious that the type of pump, whether piston or diaphragm, is immaterial to v the functioning of the present invention.

In the above-mentioned application, a diaphragm .pump has been disclosed-which is actuated by throttle movement, as well as by manifold suction. While this particular type of pump is'presently regarded as more satisfactory in operation than one actuated exclusively by either of these means separately, the actuation is not f regarded as a part of the present invention, except insofar as the elimination of gases and vapors improves pump operation and fuel metering.

. One of the objects of the invention is to provide an improved arrangement of accelerating pump for a carburetor, which incorporates a vent from the highest point in the pumping chamber.

Another object of the invention is to provide a pump chamber with a vent connected to atmosphere and a port exposed at the point of gas accumulation in the pump chamber.

Another object of the invention is to provide a pump chamber vent and valve to effectively regulate delivery of fuel from the pump. Another object of the invention is to provide a pump delivery throttling means for controlling the rate of rein section.

'Fig. 2 is an enlarged sectional view of the pump shown in'Fig. 1, in mid-stroke. I I

United States Patent'O shoe washer 36.

-Fig. 3 is an enlarged sectional view of a modified form of pump. r

Fig. 4 is an enlarged sectional view of the pump shown in Fig. 3, in mid-stroke. I

Referring, first, to Fig. 1, the drawings show a car'- buretor, generally indicated as provided with a mixing tube or conduit 11, containing the usual venturi tubes and nozzles (not shown) centrally supported in the conduit 11. A throttle shaft 12 supports a throttle valve 13 at the lower end of the mixing conduit 11, and a flange 15 is provided for attachment of the carburetor to the intake manifold of the engine. As shown in section, the source of fuel supply is a fuel line (not shown) and constant level fuel chamber 16 which includes a float and a float controlled needle valve (not shown) for. maintaining fuel therein at a constant level.

Adjacent the bottom of the fuel bowl is a metering orifice element 17 controlled by a. stepped metering pin 18 shown in its lower position in Fig. 1. Passages 19 t and 2t) connect the metering orifice element with a main nozzle passage 21. t

Within the constant level fuel chamber is a depression or cavity 22 forming a chamber which is closed at its upper side by a diaphragm 23 secured in place by an inverted cup 24. Both cup and diaphragm cooperate to form a pumping chamber 25, which communicates with the constant level fuel chamber 16 by means of anopening or conduit 26 in the upper portion of the cup 24.

An annular screen maybe provided in the upper surface of the cup, if desired, for the purpose of filtering impurities from the fuel before entry of the fuel into the pumping chamber through the opening 26. A conduit .27 is provided opening into the inverted cup 24,'which is connected with a nozzle 27a in the fuel mixture conduit 11. A continuous passageis formed by conduit26, chamber 25, and conduit 27, with chamber intermediate the'passage,

Extending upwardly from the top of the inverted cup 24 is a tubular guide 29 slidably receiving therein'a holzlow actuating stem 30 of a pumping element, which stem is connected directlywith the pump diaphragm 23 t by washers 31 and 32 secured in place at the lower end of the stem by rivet or pin 33. Stem 30 is provided with a groove orneck portion 35, which receives a horse- A coil compression spring 37 is confined between the washer 36 and the top of the cup 24, surrounding the tubular guide 29 in such a manner as to tend to -urge'stem 30 and its connected diaphragm 23 upwardly. 1

Below the diaphragm is a chamber'or cavity 22 having a port38 inthe wall thereof connected by a passage 38a to the mixture conduit 11 posterior of the throttle, so that, when the engine is operating, depress1on posterior to the throttle communicated to the cavity 22 forces the stem 30 downwardlyto its extreme lower limit. against 'the compressive force imposed by.the

' spring37.

i Also located within the constant level fuel chamber 16 is a vertical guide of rectangular cross-section (not shown) fortreceiving a gooseneck' link 41 provided with an oifset portion 42 formed with a horizontal ledge 43. Ledge 43 has'an aperture in its outer end portion slidably receiving the stem 30.' The upper, end portion of the stem 30 is of less diameter than the lower portion, forming a shoulder 44, the function of which will be later described. An angular bracket 45 has an. aperture at one end for slidably receiving the narrow portion of the stem 30, and has a pin 46-at its other end attached to the stepped metering pin 18. This bracket 45 seats on the upper side of the ledge 43, or on stem shoulder 44, whichever-happens to be .up-

--:pe1n 1ost, and itself providesa seatlfor asecond coil-.com-

pression spring 49 retained on the stem 30 by a keyed or otherwise secured washer 50. Link '41, 42- is provided at its lower end with a connection 51 in the form of a small link to an arm 52 rigid with the throttle shaft 12, so. that,

upon movement of the throttle valve '13 in an opening direction, link 41, 42 moves upwardly, carrying with it bracket 45, and thereby resiliently urging the stem 30 in an upwardly direction through the compression spring 49. Upward movement of 'the stem 30 can produce a corresponding movement of :the diaphragm 23, which, in turn, will force the fuel trapped in the pumping chamber 25 through the outlet passage 27 to the mixing conduit 11.

Likewise, when a decrease in suction occurs at'a greater rate than the rate of opening of the throttle valve 13, compression spring 37 expands and shoulder 44 on stem 30 engages bracket 45 to lift it from ledge 43 to elevate the metering pin 18 independently of throttle movement. When suction remains high, even though the throttle is being opened, diaphragm '23 may prevent any appreciable movement of the stem 30. Under high suction conditions posterior to the throttle, upward movement of the link 41, 42, due to opening movement of the throttle, raises ledge 43 and annular bracket 45 against the compression in spring 49, while stem 30 remains nearly stationary. This upward movement of bracket 45 by the throttle is relied on for raising the stepped metering pin 18, and thereby providing an increase in the rate of fuel supply to the nozzles.

During closing movement of the throttle, spring 49 again urges bracket 45 downwardly against shoulder 44 or ledge 43, whichever is uppermost, so that the lowering of the metering pin is limited by one of these elements.

From the detailed description as set forth above, the operation of the accelerator pump may be described as follows: In the first place, the movement of the stem 30 in an upward direction, and actuation of the pump 23, is under the control of mechanical means hooked to the throttle acting against spring 49 to raise stem 30. This action is aided by a spring 37 and opposed in whole or in part by pressures posterior to the throttle which are normally sub-atmospheric, acting beneath the diaphragm 23.

In the second place, actuation of the pump 23 is also under control of suction in cavity 22, since a drop in suction will cause actuation of the pump by spring 37 independent of throttle movement.

Action of the metering pin within its orifice is under the control of mechanical means to be positively raised by opening of the throttle and to be positioned independent of the throttle by upward movement of the stem 30 independent of throttle action. metering pin is efiected by drop in the degree of suction posterior to the throttle acting on the diaphragm 23 and expansion of spring 37. It follows that the metering pin may increase the flow of fuel to the mixing tube in response to (1) opening movement of the throttle, and (2) upward movement of the stem 30 under action of the spring 37 in response to decreases in suction posterior to the throttle.

The operation of the diaphragm type of accelerator pump, as a pump and as a means to position the metering pin, is entirely satisfactory so long as bubbles of air or gas do not become trapped in the inverted cup 24 above the diaphragm 23. This cannot be avoided under certain conditions, such as during idling of the engine or after the engine has ben standing inactive. It will be readily recognized that, when this happens, the bubbles may collect to form quite a large gas area extending outwardly from the top of the dome-shaped cup to the orifice 26, which vents to the fuel bowl of the carburetor. The effect of such an accumulation produces an undesirable, nonuniform response in the delivery of fuel from the outlet conduit 27 during the pumping action of the diaphragm 23, and irregular response of the pump in positioning the -metering pin, since there isno uniform damping of pump action .due to fuel in the pumping chamber. To avoid the This later movement of the tion, a means is provided to bleed otf gases from this pocket to the surface of the fuel in the fuel bowl. When gas is eliminated, pump response is regular in its action for uniform damping of metering pin movement.

Turning now to Fig. 1, a structure to carry out this purpose will be described. The stem 30 of the diaphragm pump is made tubular, as shown in 60, and is closed at both ends. Immediately adjacent the upper wall of the inverted cup 24, a port is provided, indicated as 61, open to the interior of the pumping chamber when the stem 30 is in its lowermost range of positions and closed in its upper range. This port may be of any desired size or shape. Generally, such a port is constructed by a drilling operation, and for that reason is shown to be round. However, the port 61 may be of irregular shape, if desired, so that upward stem movement will result in a pronounced effect on pump delivery due to progressive closing of the port as it enters the guide 29. Thus the vent can be designed to perform ametering function for varying pump discharge during portions of its stroke, since it will be understood that part of the pump discharge can be bypassed back to the fuel bowl through the vent passages. The opposite end of the stem beneath the necked portion 35 is provided with similar ports 62 connecting the hollow interior of the stem with the fuel bowl.

In such a structure as that above described, any gases which may become trapped within the upper portion of the inverted cup 24 will escape from the pumping chamber by way of the port 61, tubular stem 60, and port 62, above the upper surface of the fuel in the fuel bowl, from which space they may be vented, in turn, to atmosphere or mixing tube 11 by any suitable well known structure for this purpose. This modification of the pump stem provides a vent when the pump diaphragm is in its lower range of positions, which vent is automatically throttled on upward movement of the stem 30 as the port 61 enters the tubular guide 29. Thus the port and guide act together like a valve. Obviously, the liquid displacement of the pump is not affected adversely if the port 61 is small, because any fluid flowing through this vent passage is metered, by the port 61, which closes during the initial portion of the effective pumping stroke.

Turning now to the modification shown in Figs. 3 and 4, Fig. 3 shows the pump stem in its lowermost position, and Fig. 4 shows the pump stem raised to approximately intermediate position. The structure is similar to that above described, and like parts are accordingly indicated by corresponding reference characters. This pump is provided with an inverted cup 24 having a downwardlyfacing fuel intake port indicated as 63, in which is mounted a valve seat element 64 containing a vertically arranged passage 65. Valve seat element 64 is mounted in the cup by cooperating screw threads 66 on the element and on the cup. This element is also provided with a valve seat 67, upon which is mounted a valve disk 68 retained adjacent the seat by a spring ring device 69 seated in a groove in a vertically arranged valve chamber 71. Passage 72 connects with the valve chamber, and leads downwardly to a port open to the pump chamber.

As explained in the previous embodiment shown in Fig. 1, the pump stem in Figs. 3 and 4 also has a gas vent. In this modification, stem 30 is provided with a similar tubular central passage 75 closed at opposite ends except for a plurality of vertically spaced ports 76 opening into the pump chamber, and a plurality of radially spaced combined gas outlet and/or liquid metering ports 77 opening to the fuel fowl. The function of ports 77 is not only to vent the pump, but also to meter the amount of fuel to escape by way of the tubular stem 75 during the actual pumping stroke. In this respect, Fig. 3 differs from Fig. 1, wherein the metering is performed by ports .61.

It will :be understood that the operation of the pump shown in Figs. 3 and 4 is controlled in the same manne as illustrated in Fig. '1 andexplaiiied aha; f the vent'and pump intake,however,diifer slightlyin operation. It will .be noted that the intakelfor the pump is a downwardlyfacmg passage whereby induction into the pump of vapors .cation,'pump inlet 26 is intended to act merely as an auxiliarypassalge to allow the fuelto leak in and fill the pump chamber when the engine is not operating, and thereby replace fuel evaporated from the chamber and escapingin the form of vapors through the vent.

The structure for venting the pump, and thereby eliminating any accumulation of gases and vapors collecting in. the inverted cup adjacent thestem, is accomplished in a slightlyditferent manner. In this instance, a plurality of vertically spaced ports 76, all of which are open in the lower range of positions of the stem 30, and which are progressively throttled during the upward stroke of the pump, perform the venting action. From an inspection of Fig. 3 it will be obvious that any accumulation of gases adjacent the stem, as shown by dotted line in this fig., may'escape by way of the topmost one of the ports 76, tubular stem 75, and radially spaced ports 77. When the pump is in its lowermost range of positions, the upper one of ports 76 is positioned to accommodate this function. As the stern rises during its operative pumping stroke, ports 76 are successively sealed off or throttled, as shown in Fig. 4, and each of the ports is successively raised to a position wherein it becomes effective as a vent, so that, as the pump approaches or reaches intermediate range, only one of the ports 76, the lowest, remains open, but it is in turn positioned so as to be elf-ective as a vent. Above this range a vent is not necessary, and all the ports are throttled. In this respect the ports 76 act as valves.

Since it is possible for liquids, as well as gases, to escape through these ports, the size of the ports must necessarily be restricted, or the pump will have very little displacement, even though ports 77 are above the outlet from fuel nozzle 27a and during pump action fuel would normally reach nozzle 27a before leaking out by way of ports 77. This restriction to the liquid escape is performed generally by metered ports 77. However, this function of ports 77 may be materially affected by successive closing of ports 76, if desired. In the initial portion of the pump stroke, the diaphragm movement tends to be rapid and, for this reason, the venting area provided by the ports 76 may be considerably larger without affecting the capacity of the pump materially. Before the stem reaches its intermediate range of positions, however, the pumping action is slowed to some extent because the pumping pressure exerted by the spring 37 has decreased. For this reason, the venting area should be cut down, and the possible route of escape of fuel through the vent should be materially decreased. The structure shown in Figs. 3

and 4 quite clearly illustrates all of these desirable features and, at the same time, maintains a gas vent open until throttle-opening position or manifold pressure has positioned the pump in the intermediate range or portion of its stroke.

It has been found that the venting means described materially benefits the action of the carburetor and combines with the specific actuating means for the pump to effect a substantial improvement in the performance 'of the carburetor as a whole.

Only two embodiments of the present invention have been illustrated, but it will be obvious to those skilled in the art that numerous other mechanical devices of well known form and type might be combined to. be operated by the pump-actuating mechanism herein disclosed to perform exactly the same function and achieve the same results. It is believed, therefore, that the claims appended as stand teata 'mttr t; the light of the atest disclosure, but not restricted thereby.

1. In a carburetor, the combination'ofa throttle-controlled fuel and air mixing tubeg alconstant level fuel chamber and passage to said tube, a pump including a pumpingchamber intermediate said passage, a guide in one of said chambers and a pump element having a stem in said guide extending above the fuel level in said other chamber, means responsive to throttle action for operating said pump and means forventing one of said chambers comprising a passage in said stem with openings above the fuel level in the other chamber, a metering means for said passage, and a pump-controlled means for progressively throttling said vent means.

' 2. ha carburetor, the combination of a throttle-controlled fuel and air mixing tube, a constant level fuel chamber and passage to said tube, a pumpincluding. a pumping chamber intermediate said passage, a guide in one of sald chambers and a pump element having a stern in said guide extending above the fuel level in the other said chamber, means responsive to throttle action for operating said pump and means for venting one of said chambers comprising a passage in said stem communicating with the other said chamber, a metered opening above the fuel level in said fuel chamber, and a pump-controlled means for progressively throttling said vent means.

3. In a carburetor, a throttle, a source of fuel, an accelerating pump including a pump chamber and a guide in said source, a pumping element in said chamber, a stem on said element slidable in said guide, resilient means under control of said throttle for operating said pump, and a vent for said pump comprising a passage within said guide communicating between said chamber and said source, open in one range of positions of said pumping element and closed within another range of positions thereof in response to change in throttle position.

4. In a carburetor having a throttle, the combination of a source of fuel, an adjustable fuel metering device, a resiliently operated means for adjusting said metering device under control of said throttle, including a damping mechanism having a chamber in communication with said source, a vent for gases and vapors in said mechanism leading from said damping chamber to atmosphere, and means for throttling said vent for producing uniform adjustment of said metering device in response to action of said resilient means.

5. In an accelerating pump structure for a carburetor having a fuel chamber, a pump chamber separated from said fuel chamber, a fuel inlet from said fuel chamber to said pump chamber, a fuel outlet from said pump chamber, a gas vent in a wall of said pump chamber, a pumping member movable in one direction in said pump chamber to draw fuel from said fuel chamber through said fuel inlet into said pump chamber and movable in another direction to discharge fuel from the pump chamber through said outlet, and an element movable with said pumping member for closing said gas vent upon initial movement of said pumping member in said other direction from its charged position.

6. In an accelerating pump structure for a carburetor having a constant level fuel chamber, a pump chamber separated from said constant level chamber by a wall hav ing a stem guide bearing aperture, a fuel inlet passage leading from said fuel chamber to said pump chamber, a movable pumping element in said pump chamber, a stem secured to said pumping element and extending upwardly through said bearing aperture, a gas vent passageway in said stem having an inlet port disposed within the pump chamber below and adjacent said wall when said pumping element is in a lower retracted position, said gas vent passageway having an outlet port disposed to vent gases to the atmosphere, a fuel outlet passage leading from said pump chamber, and means to move said pumping element upwardly from its retracted position toward 7 said wall to first close said inlet port within said wall and then to force fuel from said pump chamber outwardly through said fuel outlet.

7. In an accelerating pump structure for a carburetor having a constant level fuel chamber, a pump chamber disposed below said fuel'chamber and separated therefrom by a wall having a stem guide bearing aperture, a fuel inlet passage leading from said fuel chamber .to said pump chamber, a pump element in said pump chamber, a stem secured to said pump element and extending upwardly through said bearing aperture into said fuel chamber, a gas vent passageway in said stem having an unobstructed inlet port disposed within the pump chamber below and adjacent said wall when said pump element is in a lower retracted position, said gas vent passageway having an outlet port disposed to vent gases into said fuel chamber above the fuel level therein, a fuel outlet passage. leading from said pump chamber, resilient means to move said pump element upwardly from its retracted position toward said Wall to first confine and close said inlet port within said wall and then to force fuel from said pump chamber outwardly through said fuel outlet, and means for moving saidv pump element toward its retracted position to draw fuel from said'fuel chamber intosaid pump chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,003,420 Babitch et a1 June 4, 1935 2,022,660 Flint Dec. 3, 1935 2,080,391 Rockwell May 11, 1937 2,130,915 Whisler Sept. 20, 1938 2,212,946 Mock et al Aug. 27, 1940 2,235,797 Carlson Mar. 18, 1941 2,299,863 Trisler Oct. 27, 1942 2,619,333 Carrey Nov. 25, 1952 FOREIGN PATENTS 422,850 Great Britain Jan. 17, 1935

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