US3323293A - Primer for internal combustion engines - Google Patents

Description

June 6, 1967 J. D. SANTI PRIMER FOR INTERNAL COMBUSTION ENGINES Filed Feb. 25, 1965 3 Sheets-Sheet l jmOnwfiLd J0 hn Eat-Liz J. D. SANTI PRIMER FOR INTERNAL COMBUSTION ENGINES Filed Feb. 23, 1965 June 6, 1967 3 Sheets-Sheet 2 A i .I

June 6, 1967 J. D. SANTI 3,323,293

PRIMER FOR INTERNAL COMBUSTION ENGINES 5 Sheets-Sheet 5.

Filed Feb. 23, 1965 III,

Ill/I United States Patent '0 Delaware Filed Feb. 23, 1965, Ser. No. 439,502 9 Claims. (Cl. 55-385) This is a continuation-in-part of my application Ser. No. 378,576, filed June 29, 1964, now abandoned.

This invention relates broadly to internal combustion engines and refers more particularly to the fuel supply systems of single-cylinder engines of the type now widely used on lawn mowers, snow blowers, garden cultivators, and other similar implements.

The purpose and object of this invention is tomake starting of such engines easier.

Conventionally, the carburetor in the fuel supply systems of small single-cylinder gasoline engines was equipped with a choke valve to control the admission of air and thereby regulate the richness of the fuel-air mixture drawn into the engine.

In starting the engine, the operator was expected to close the choke valve so that the fuel mixture drawn into the engine during cranking would be sufliciently rich to assure starting, and then as soon as the engine started the choke valve had to be reopened to prevent flooding the carburetor. The need for making these adjustments was a source of annoyance; and while the remote controls with which some engine-driven implements were equipped did facilitate actuation of the choke valve, an adjustment after the engine started still had to be made; and if it was not made promptly the engine would stall. This meant trouble, at least to the inexperienced operator.

The present invention obviates the need for making such quick adjustments, by the simple expedient of replacing the choke valve of the carburetor with a priming pump. It is realized that the use of priming pumps to inject fuel directly into the carburetor of an engine is not new, but the manner in which the present invention combines the priming pump and the control thereof with the carburetor and the fuel tank of the engine to afford an extremely simple and inexpensive arrangement is believed to be novel.

The invention is particularly adapted to engines wherein the fuel tank and the carburetor are combined into a unitary assembly, with the carburetor mounted on the top wall of the fuel tank, so. that fuel may be drawn directly from the tank into the mixing passage of the carburetor. In such carburetor-fuel tank assemblies, the air inlet opening of the carburetor faces upwardly and has an air filter removably mounted thereon, the filter being held in place by a screw which passes axially down through the air filter and is threaded into the bottom wall of the carburetor mixing passage.

With a view toward achieving utmost simplicity and economy in manufacturing costs, this invention has as a specific object to provide a carburetor-fuel tank assembly with a priming pump, which assembly is so arranged and constructed that the screw that holds the air filter in place is tubular, and the actuator for the pump is slideably received in said screw.

Another important objective attained in one embodiment of the present invention is to provide a primer pump for injecting a charge of fuel from a fuel tank into the air passage of a carburetor, which pump has a very simple cup-shaped plunger element and needs no valves.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiments of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of physical embodiments of the invention, constructed according to the best modes so far devised for the practical application of the principles thereof, and in which FIGURE 1 is a perspective view of a carburetor-fuel tank assembly embodying this invention, with parts broken away and in section;

FIGURE 2 is a view similar to FIGURE 1 but illustrating a modified embodiment of the invention;

FIGURE 3 is a vertical sectional view through the assembly shown in FIGURE 2, drawn to a larger scale and showing the plunger element of the primer pump in its normal or discharging position;

FIGURE 4 is a View similar to FIGURE 3 but showing the plunger element in its filling position; and

FIGURE 5 is a fragmentary sectional view taken on the same plane as FIGURES 3 and 4 and showing details of the passage which communicates the primer with the carburetor mixing passage.

Referring now particularly to the accompanying drawings, the numeral 5 designates generally the entire carburetor-fuel tank assembly of this invention, and which comprises a fuel tank 6 having a top wall 7 and a carburetor 8 mounted on the top wall of the tank. The top wall 7 of the fuel tank and the carburetor body are preferably formed as die castings.

The carburetor has a mixing passage 9 with an upwardly facing air inlet 10 at one end thereof and an outlet 11 at its other end that is connected by a tube 12 to the intake port of the engine, not shown. A mounting flange 13 on the body of the carburetor seats fiat upon a mounting pad on the top wall 7 of the fuel tank, and is remova-bly secured thereto by screws 14. A thin, re.- silient membrane-like gasket 35, of neoprene or the like, is confined between the flange and the mounting pad to provide a seal where fuel passages continue across the junction between the fuel tank and the carburetor body.

Depending from the top wall 7 of the fuel tank is a fuel reservoir 15 into which fuel is pumped from the tank by means of an engine-suction-responsive pump (not shown) and from which fuel is drawn into the mixing passage 9 through an eduction tube 16 which leads to a needle valve controlled orifice that opens into the mixing passage. Since the manner in which fuel is pumped from the tank into the reservoir 15 and withdrawn from it into the mixing passage forms no part of the present invention, these features have not been detailed in the drawing. Moreover, reference may be had to the copending Catterson application, Ser. No. 270,949, now abandoned, which illustrates these particular features.

As in the past, an air filter 17 is removably held in position on the inlet end of the carburetor mixing passage by means of a long retaining screw 18, which passes axially down through the air filter and is threaded, as at 19, into the bottom wall of the mixing passage. A knurled head 18' on the screw provides means by which the screw can be turned and a shoulder to bear down on the cover of the air filter.

The recently issued Lechten berg Patent No. 3,118,433, illustrates the general organization thus far described; but whereas, in the prior structures, the air inlet opening 10 was equipped with a choke valve to be closed during cranking of the engine-at least when the engine was coldthere is no such choke valve in the present invention. The air inlet opening 10 leading to the mixing passage is always fully open.

To obtain the necessary enrichment of the fuel mixture l or starting purposes, a priming pump, indicated generlly by the numeral 20, is provided. This pump supplants he conventionally used choke valve, and upon actuation hereof, squirts a jet of fuel directly into the mixing pasage.

Simplicity and a remarkably practical construction .haracterize the manner in which the priming pump s incorporated into the carburetor-fuel tank assembly. Thus as illustrated in FIGURE 1 the priming pump has t tubular element 21 which is cast integrally with the op wall 7 of the fuel tank, and more particularly, with he bottom of the reservoir 15, from which the tubular :lement rises inside the reservoir and projects downwardvy beneath the reservoir. The tubular element 21 has a nulti-diameter bore that decreases stepwise in width toward the bottom thereof to provide a pair of vertically spaced upwardly facing circumferential shoulders and 36 and to provide a plunger chamber or cylinder 21 of the pump in the widest portion of the bore, above the upper circumferential shoulder 25. The height of the plunger chamber 21 is such that its open upper end bears against the underside of the carburetor in line with a priming hole or port 22, which opens to the mixing pas sage. Accordingly, upon upward movement of a plunger element or piston 23 in the chamber 21, fuel contained in the plunger chamber is projected through the hole or port 22 directly into the mixing passage.

The plunger element or piston 23 is biased upwardly by a compression spring 24 confined between the plunger and the shoulder 25 at the junction of the plunger chamber with a smaller diameter portion 26 of the bore of the tubular element, in its bottom portion. The tubular element projects downwardly to a point near the bottom of the fuel tank, where it has an inlet port 27 defined by the smallest diameter portion of the bore therein. Fuel flow through the inlet port 27 is controlled by a ball check valve 27' that is gravity biased into engagement with the lower circumferential shoulder 36, which serves as a seat for the ball.

The plunger element or piston 23 is somewhat smaller in diameter than the bore of the plunger chamber 21, but has an integral, relatively flexible upwardly facing circumferential lip 28 at its top which snugly engages the bore of the plunger chamber when in its normal unflexed condition. Hence, during upward movement of the plunger or piston, the ball check valve is lifted off its seat and fuel is drawn from the tank into the bottom portion of the tubular element 21; and upon depression of the plunger or piston, the fuel trapped in the lower portion of the tubular element by closure of the ball check valve, deflects the lip 28, which thus may be considered a unidirectional valve means, and passes to the top side of the plunger element or piston, to be lifted thereby and expelled from the chamber through the outlet port 22 when the spring 24 forces the plunger element or piston upward.

It is important to observe that the plunger chamber is coaxial with the upwardly opening inlet 10 of the mixing passage, and that the screw 18 by which the air filter is held in place is tubular. By virtue of this coaxiality and the tubular nature of the screw 18, utmost simplicity in the actuation of the pump is possible. Thus, as shown, an actuator stem or push rod 30 with a head or button 31 on its outer end, passes slidably down through the tubular retaining screw 18 to project into an elongated socket 32 in the plunger element 23. There is no need for the stem 30 to be fixed to the plunger, since the upward bias of the spring on the plunger element holds it against the end of the stem and a shoulder 33 formed on the stem-'by pinching the same to form oppositely projecting earsengages the lower end of the tubular screw 18 to hold the same against upward displacement beyond its normal potentially operative position.

In operating the priming pump, it is only necessary to momentarily depress the actuating button 31. This forces down the plunger element or piston 23 and causes fuel which had been trapped in the lower end portion of the plunger chamber by a preceding actuation of the piston, to pass between the flexible lip 28 of the piston and the wall of the chamber bore. Upon release of the button 31, the spring 24 forces the piston up and, in so doing, expels the fuel from the plunger chamber and sprays or squirts it into the mixing passage 9 through the priming port or hole 22.

In the embodiment of the invention illustrated in FIG- URES 25, the air cleaner 17 is again secured in place on the upwardly opening inlet 10 of the carburetor mixing passage 9 by means of a tubular screw 18 which is threaded, as at 19, into the bottom wall of the mixing passage; and an elongated stem or push rod 30' extends through the tubular screw, to be accessible at the top thereof for actuation of a plunger element 23'. In this instance, too, the plunger element cooperates with a stationary tubular element 121 which is secured to and projects downwardly from the top wall 7 of the fuel tank, in axial alignment with the tubular screw, and which has its lower end spaced above the bottom wall 47 of the fuel tank.

However there is no check valve in the FIGURES 2-5 version of the invention, and the plunger element 23 is cup-shaped and is disposed beneath the tubular element to be moved to and from telescoping relation therewith, so that the plunger element comprises a movable cylinder and the tubular element comprises a cooperating stationary piston.

As shown, the tubular element 121 is made of material which is sufficiently resilient to be deformable under substantial pressure and has a larger diameter upper end portion 48 which is press fitted into a hole in the top wall 7 of the fuel tank, directly beneath and coaxial with the threaded connection 19 of the tubular screw 18 to the carburetor body. At least the lower portion of the tubular element has a uniform outside diameter along its length so as to have a close sliding fit in the cupshaped plunger element 23'. To insure a good seal between the sliding surfaces of the tubular element and the plunger element, the latter preferably has a small radially inwardly projecting circumferential flange or lip 49 around its rim portion.

The plunger element also has a radially outwardly projecting circumferential flange 50 on its rim portion that provides a downwardly facing seat for a coiled compression spring 24 that surrounds the cylindrical wall of the plunger element and has its lowermost convolution received in a well 51 in the bottom wall 47 of the fuel tank.

The axial height of the cup-shaped plunger element is substantially less than the distance between the lower end of the tubular element 121 and the bottom wall of the fuel tank therebeneath, so that when the plunger element is fully depressed aganist the bias of spring 24', as shown in FIGURE 4, fuel from the tank can flow over its rim and fill the plunger element.

Such downward displacement of the plunger element can be effected by means of the stem or push rod 30, which in this case is made in two sections and 230 so as to permit the air cleaner to be removed from the carburetor body without the need for disassembly of the priming pump. The lower section 130 of the push rod is coaxially secured at its bottom to the bottom wall of the cup shaped plunger element, and may be threaded thereinto, as shown, or formed integrally therewith. The lower push rod section 130 extends with a small clearance through the bore 51 in the lower portion of the tubular element and projects upwardly a short distance into a counterbore 52 in the upper end portion of the tubular element, where it endwise abuts the upper section 230 of the push rod. The upper section 230, which extends through and projects above the tubular screw 18', can

have the same diameter as the lower section and has outwardly projecting cars 33 near its lower end which prevent its inadvertent withdrawal from the tubular screw.

In this instance the head 118 on the tubular screw is shown as generally cup-shaped, and its side wall has a large enough inside diameter to receive the pushbutton 31 on the upper end of the push rod, and has sufficient depth so that it projects up nearly to the normal level of the pushbutton. The cup-shaped head 118 thus serves as a guard which prevents inadvertent depression of the pushbutton.

It will be observed that the upper and lower push rod sections 230 and 130 are normally maintained in endwise abutting relationship by gravity acting on the upper section 230, and that the plunger element is normally fully telescoped over the lower end of the tubular element under the biasing force of spring 24, as illustrated in FIGURE 3.

To effect priming of an engine with the apparatus of FIGURES 2-5, the pushbutton 31 is fully depressed, to move the plunger element down to its filling position illustrated in FIGURE 4. Fuel very quickly fills the cupshaped plunger element and at the same time rises in the bore of the tubular element to substantially the level that obtains in the tank. When the pushbutton is released, spring 24' propels the plunger element upwardly into telescoping relationship with the tubular element, to the normal position shown in FIGURE 3. Because of the close sliding fit between the plunger and tubular elements, the tubular element displaces fuel out of the plunger element as the latter rises, and such displaced fuel is constrained to move upwardly along the bore of the tubular element and through a small transfer passage 22 that communicates the upper end of the counterbore with the mixing passage in the carburetor.

As illustrated in FIGURE 5, the transfer passage 22' is valved to prevent air from being sucked into the bore of the tubular element when the plunger element is depressed, such valving being provided by a portion of the membrane-like gasket 35 that is confined between the carburetor body and the top wall of the fuel tank. Specifically, the top wall of the fuel tank is formed with a small depression 55 in its upper surface which is overlain by the gasket 35 and which is located directly beneath an upwardly opening passage section 56 in the carburetor body that leads to the mixing passage. The depression 55 is also directly beneath the inner end of a laterally extending groove 57 in the underside of the carburetor body that defines a passage section leading fro-m the upper end of the counterbore 52. The transfer passage 22' consists of passage sections 56 and 57 and a connecting section defined by depression 55. Under fluid pressure produced by the priming pump the gasket portion above the depression 55 is displaced down into the depression to allow fuel to flow from passage section 57 to passage section 56; :but when suction is manifested in passage section 57 the membrane is drawn up thereby to seal the inner end of that passage section against the entry of air. In this manner assurance is had that under ordinary circumstances adequate priming can be effected by a single depression of the pushbutton.

It will be observed that the lower end of the tubular element is beveled, and the rim of the cup-shaped plunger element is correspondingly beveled at its inner surface, so that the plunger element is guided into telescoping engagement with the tubular element in spite of any lateral displacement of the plunger element that might result from the loose fit of the lower push rod section 130 in the bore of the tubular element.

From the foregoing description taken in connection with the accompanying drawings it will be apparent to those skilled in this art that this invention simplifies the starting of internal combustion engines by supplanting the heretofore customary choke valve and its indecisive action and annoying need for adjustment both before and after cranking, substituting for the choke valve a conveniently and easily actuated priming pump; and that this invention achieves its purpose in a very practical and exceedingly simple manner.

What is claimed as my invention is:

1. In combination:

(A) a fuel tank for an internal combustion engine,

said tank having a top wall;

(B) a carburetor mounted on the top wall of the fuel tank and having a mixing passage with an upwardly facing air inlet;

- (C) an air filter seated on the inlet of the mixing passage;

(D) a tubular screw passing down through the air filter and threaded into the bottom wall of the mixing passage to hold the air filter in position;

(E) a priming pump carried by the top wall of the fuel tank and located inside the tank in line with said tubular screw, said priming pump having an inlet opening to the interior of the fuel tank and an outlet which passes through the bottom wall of the mixing passage;

(F) a plunger for the priming pump; and

(G) an actuator for the plunger reciprocably received in the tubular screw and having a handle portion at the upper end thereof.

2. An internal combustion engine fuel system of the type comprising a fuel tank having a top wall, a carburetor mounted on said top wall and having a horizontally extending mixing passage with an upwardly facing air inlet, and an air filter removably seated on the inlet of the-mixing passage, said fuel system being characterized by the following:

(A) a tubular screw passing down through the air filter and threaded into the bottom wall of the mixing passage to hold the air filter in position;

(B) a reciprocatory primer pump in the fuel tank, beneath said tubular screw and coaxial therewith, said pump comprising (1) a stationary upright tubular element having a bore that communicates at its upper end with a passage that opens to the mixing passage and is communicable at its bottom with the interior of the fuel tank, and

(2) a plunger element which is movable up and down and which cooperates with said tubular element for pumping fuel from the fuel tank to the mixing passage; and

(C) an elongated actuator for said plunger element extending coaxially through the tubular screw and having (1) a handle portion at its upper end, above the tubular screw, by which the actuator can be reciprocated, and

(2) a driving connection with the plunger at its lower end.

3. The internal combustion engine fuel system of claim 2 wherein said primer pump is further characterized :by the following:

(A) said upright tubular element is secured to the top wall of the fuel tank and projects downwardly therefrom, and has its lower end spaced above the bottom of the tank;

(B) said tubular element has a multi-diameter bore, decreasing in width toward the bottom thereof, to define (1) a lowermost upwardly facing circumferential shoulder which provides a valve seat and (2) a higher upwardly facing circumferential shoulder which provides a spring seat;

(C) a gravity biased valve element cooperates with said valve seat to permit upward fiow of fuel through the bore in the tubular element and to block downward flow of fuel therethrough;

(D) the plunger element is reciprocable in the bore in the tubular element above said spring seat and has a resiliently flexible radially projecting lip that is normally in sealing circumferential engagement with the inner Wall surface of the tubular element but is adapted to be flexed upwardly by the reaction of fuel to downward movement of the plunger element; and

(E) a coiled compression spring in said bore reacts between said spring seat and the plunger element to bias the latter upwardly.

4. The internal combustion engine fuel system of claim 1 wherein said primer pump is further characterized by he following:

(A) said upright tubular element is secured to the top wall of the fuel tank and projects downwardly therefrom, and has its lower end spaced above the bottom of the fuel tank;

(B) the plunger element (1) is cup shaped,

(2) has a close telescoping fit with the lower end portion of the tubular element, and

(3) has an axial height which is substantially less than the space between the lower end of the tubular element and the bottom of the tank so that the plunger element can occupy a position spaced below the bottom of the tubular element and in which fuel from the tank can flow into the plunger element over its rim; and

(C) a coiled compression spring reacts between the bottom of the tank and the plunger element to bias the latter upwardly toward telescoped relationship with the tubular element.

5. The internal combustion engine fuel system of claim 2, further characterized by the fact that said tubular screw has a cup-shaped head, the bottom wall of which overlies the air filter to hold the same in place and the side walls of which project upwardly and substantially surround the handle portion of the actuator to prevent inadvertent movement of the same.

6. In an internal combustion engine fuel system having a fuel tank with opposite spaced apart top and bottom walls and a carburetor having a mixing passage, a primer pump by which a charge of fuel can be injected into the mixing passage, said primer pump comprising:

(A) a stationary tubular element secured to the top wall of the fuel tank and projecting downwardly therefrom with its lower end spaced a distance above the bottom wall of the fuel tank;

(B) means defining a passage which communicates the upper end portion of the bore in the tubular element with the mixing passage;

(C) a substantially cup-shaped plunger element having an inside diameter at its rim which provides a substantially close sliding fit with the lower portion of the tubular element and having a height less than the distance between the bottom wall of the fuel tank and the bottom of the tubular element so that the plunger element is axially movable between a lowermost filling position in which fuel from the tank can flow into the plunger element over the rim thereof and a discharging position in which the plunger element is telescoped over the lower portion of the tubular element; I

(D) a compression spring reacting between the bottom wallof the fuel tank and the plunger element to bias the latter towards its discharging position; and

(B) an upright push rod coaxially connected at its lower end with the plunger element, extending upwardly through the bore in the tubular element, and having its upper end portion projecting above the t3 tubular element to be accessible for depression of the plunger element to its filling position against the bias of said spring.

7. An internal combustion engine fuel system of the type comprising a fuel tank having a top wall, a carburetor mounted on said top wall and having a horizontally extending mixing passage with an upwardly facing air inlet, and an air filter, said fuel system being characterized by:

(A) means for readily detachably holding the air filter seated on the inlet of the mixing passage, comprising (1) a tubular element extending through the air filter and having a connection with the bottom wall of the mixing passage, and

(2) means having a connection with the upper end of the tubular element and having a downwardly facing shoulder which overlies the air filter, one of said connections being readily detachable;

(B) a reciprocatory primer pump in the fuel tank, beneath said tubular element and coaxial therewith, said pump comprising (1) a stationary upright tubular pump member having a bore that is communicated at its upper end with the mixing passage and is communicable at its bottom with the interior of the fuel tank, and

(2) a plunger member which is movable up and down and which cooperates with said tubular pump member for pumping fuel from the fuel tank to the mixing passage; and

(C) an elongated actuator for said plunger member extending coaxially through the tubular element and having (1) a handle portion at its upper end, above the tubular element, by which the actuator can be reciprocated, and

(2) a driving connection with the plunger member at its lower end.

8. The fuel system of claim 7, wherein there is a fuel reservoir in the upper portion of the fuel tank with the bottom thereof spaced down from the level of the top wall of the tank, further characterized in that:

(A) the tubular pump member is integral with the bottom of said reservoir and has its top contiguous to the bottom of the carburetor, and

(B) the carburetor mixing passage has a hole through its bottom wall through which the upper end of the bore in the tubular pump member is communicated with the mixing passage.

9. The internal combustion engine fuel system set forth in claim 7, further characterized by:

(A) means biasing the plunger member upwardly;

(B) valve means on the plunger member which opens during downward depression of the plunger member and closes upon upward movement thereof; and

(C) a check valve near the lower end of the bore in the tubular pump member arranged to open upon upward movement of the plunger member.

References Cited UNITED STATES PATENTS 2,101,536 12/1937 Ericson. 2,999,562 9/ 1961 Lechtenberg. 3,118,433 1/1964 Lechtenberg 12341.31 3,188,060 6/ 1965 Kalert.

HARRY B. THORNTON, Primary Examiner.

RONALD R. WEAVER, Examiner.

Claims (1)

1. IN COMBINATION: (A) A FUEL TANK FOR AN INTERNAL COMBUSTION ENGINE, SAID TANK HAVING A TOP WALL; (B) A CARBURETOR MOUNTED ON THE TOP WALL OF THE FUEL TANK AND HAVING A MIXING PASSAGE WITH AN UPWARDLY FACING AIR INLET; (C) AN AIR FILTER SEATED ON THE INLET OF THE MIXING PASSAGE; (D) A TUBULAR SCREW PASSING DOWN THROUGH THE AIR FILTER AND THREADED INTO THE BOTTOM WALL OF THE MIXING PASSAGE TO HOLD THE AIR FILTER IN POSITION; (E) A PRIMING PUMP CARRIED BY THE TOP WALL OF THE FUEL TANK AND LOCATED INSIDE THE TANK IN LINE WITH SAID TUBULAR SCREW, SAID PRIMING PUMP HAVING AN INLET OPENING TO THE INTERIOR OF THE FUEL TANK AND AN OUTLET WHICH PASSES THROUGH THE BOTTOM WALL OF THE MIXING PASSAGE; (F) A PLUNGER FOR THE PRINTING PUMP; AND

Images