US 3238886 A
Description (OCR text may contain errors)
March 8, 1966 JOHNSON 3,238,886
FUEL PUMP Filed Jan. 11, 1965 INVENTOR ELDON A.JOHNSON, DECEASED,
ATTORNEY BY DOLORES JOHNSON, ADMINISTRATRIX,
United States Patent O 3,238,886 FUEL PUMP Eldon A. Johnson, deceased, late of St. Louis County,
Mo., by Dolores Johnson, administratrix, St. Louis County, Mo., assignor to ACF Industries, Incorporated,
New York, N.Y., a corporation of New Jersey Filed Jan. 11, 1965, Ser. No. 424,860 6 Claims. (Cl. 103-150) The present application is a continuation-in-part of application Serial Number 239,898 filed November 26, 196 2 which matured into Patent No. 3,182,601.
This invention is directed to fuel pumps and more particularly to a fuel pump adapted for use especially with small carburetors and small internal combustion engines, such as employed in power saws or power mowers.
Small inexpensive fuel pumps have been devised with may be added to the fuel system somewhere in the fuel line between the carburetor and the source of fuel. An example of such a diaphragm fuel pump is disclosed in the above cope-n-ding application Serial Number 239,898 of Eldon A. Johnson. Such fuel pumps consist of a small diaphragm forming a pair of chambers within a housing, one on either side of the diaphragm. One chamber is connected directly to the crankcase of the internal combustion engine, if it is a two-cycle engine, or to the intake manifold in a four-cycle engine installation. The other chamber in the housing is the pumping chamber for the fuel and is connected through check value passages to the source of fuel and to the carburetor. Pulsations provided by the engine during operation reciprocate the pump diaphragm to pump fuel from the source into the carburetor.
The pump structure is formed of a pair of intercfitting body members which are merely snapped together to clamp or grip a diaphragm positioned between the two body members. The body members are formed with matching or mating portions and one body member may be rotated relative to the other about a common axis allowing the pump to be adapted to any carburetor without requiring a specific fixed arrangement of the inlet and outlet nipples for each particular installation. To prevent leakage and assure efiicient operation, the diaphragm must be tightly sealed and gripped about its marginal portion when the two interfitting body members of the pump are snapped together.
The diaphragm is directed toward the pumping chamber at the end of its pumping stroke and it is desirable that the gripped marginal portion of the diaphragm slope toward the pumping chamber to eliminate stressing of the diaphragm adjacent the gripped marginal portion. On the suction stroke of the pump, bending of the diaphragm adjacent the inner wall surface of the fuel pump is in one direction which permits a rolling action of the diaphragm without reversal of any loop formed adjacent the marginal portion. Reversing of a loop in the diaphragm is defined as a change in the curvature of a loop from convex to concave upon movement of the diaphragm between strokes.
It is an object of the present invention to provide a fuel pump having a diaphragm which is easily gripped and sealed between two interfitting body members of the pump with a minimum of stressing of the diaphragm upon movement during strokes.
An additional object is the provision of such a fuel pump in which any tendency of a loop in the diaphragm to reverse is eliminated.
A further object is to provide such a fuel pump having a diaphragm between two interfitting clamping body members with the body members arranged for relative rotative movement and the diaphragm easily gripped and held in sealed position without the necessity of any separate securing means.
Briefly described, the invention comprises a fuel pump having a pair of interfitting body members with one of the body members being cup-shaped and having an outer annular rim and an annular shoulder adjacent the rim forming a seat, the other of the body members having an annular extension telescoping within the cup-shaped member and adapted to be positioned adjacent the annular shoulder, and a circular diaphragm positioned across and sealed along its marginal portion between the annular extension and the annular shoulder, the annular seat and the annular extension having complementary oppositely facing generally smooth and parallel surfaces each sloping inwardly in a direction toward the fuel or pumpi-ng chamber so that the surfaces of the diaphragm form smooth continuations of the surfaces of the annular seat and annular extensions at the end of the pumping stroke whereby stressing of the diaphragm at the end of the pumping stroke is at a minimum and any tendency of the loop in the diaphragm to reverse is eliminated. Other objects and features will be in part apparent and in part pointed out hereinafter.
The invention accordingly comprises the construction hereinafter described, the scope of the invention being indicated in the following claims.
In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated:
FIGURE 1 is a plan view of a fuel system comprising a carburetor attached to the manifold of an engine with the novel pump of this invention installed on the carburetor and connected to a source of fuel;
FIGURE 2 is a sectional view of the pump of FIG- URE 1 showing the pump mounted on the carburetor;
FIGURE 3 is a sectional view taken general-1y along line 33 of FIGURE 2;
FIGURE 4 is a top plan of the lower body member of the pump shown in FIGURES 2 and 3, the upper body member being removed; and
FIGURE 5 is an enlarged fragment of FIGURE 2 showing means for gripping and scaling the marginal portion of the diaphragm.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawing.
FIGURE 1 discloses a diaphragm fuel pump embodying a fuel system for a four-cycle operation. A carburetor indicated at 10 is mounted upon the intake manifold M of an internal combustion engine -E, which, for example, is a four-cycle engine. A fuel pump 12, in accordance with the invention, is mounted on the carburetor and is connected by a flexible tubing 14 from a nipple structure 16 to a fitting 18 to provide an air conduit between the engine intake manifold and pump 12. Another laterally extending nipple structure 20 is connected by fuel line 22 to a source of fuel, such as a fuel tank 24 schematically shown. The carburetor may be of a well-known type and consists primarily of a tubular air and fuel mixture conduit 26 attached by a flanged end 25 to the engine manifold, such as by stud 28 extending from the engine block. At the other end, an air filter housing 30 provides an opening to the mixture conduit 26. Within the filter housing 30 is a porous filter for removing dust and other particles from the air entering the carburetor. Rotatably mounted within the carburetor are a throttle valve structure 32 and a choke valve structure 34 to control the flow of air through the carburetor. Other details of the carburetor are well-known and are not illustrated.
Carburetor 10 is operated in a conventional manner to permit air flow into the engine manifold and to mix with the air a controlled amount of fuel to provide the proper combustible air and fuel mixture. Details of the fuel pump 12 are shown more specifically in FIGURES 2 and 3. Pump 12 consists essentially of a pair of interfitting oppositely facing cup-shaped body members generally designated 36 and 38. Diaphragm 40 is gripped along a peripheral marginal portion 41 between body members 36 and 38 and may be of any appropriate material, such as a fabric coated with a fuel resistant synthetic rubber material to provide suflicient flexibility and strength. A fuel pumping chamber 42 is formed between diaphragm 40 and lower cup-shaped member 38 while a substantially closed air chamber 44 is formed within upper cup-shaped member 36. Positive pressures in intake manifold M are relatively small and variable when the pump is utilized with a four-cycle engine. Thus, a coil spring 46 is positioned within an annular groove 48 of body member 36 to form a seat for one end of spring 46. Spring 46 drives the pump while providing a uniform pumping stroke and is loaded by the negative pressures in the intake engine manifold which are sufficient to fully load the spring.
Nipple 16 extends laterally from the top of cup-shaped member 36 while nipple 20 extends laterally from the bottom portion of cup-shaped member 38. Nipple 16 is formed with a passage 50 therethrough which connects air chamber 44 with flexible tubing 14 to manifold M of the engine. In a similar manner, a fuel inlet passage 52 extends through nipple 20 to connect pumping chamber 42 with fuel line 22 leading from fuel tank 24.
An inlet valve structure 54 is inserted in a short portion of fuel inlet passage 52 leading into chamber 42 and in a similar manner an outlet valve structure 56 is fitted within a short outlet passage through the bottom of cupshaped member 38 connecting chamber 42 with an outlet chamber 58.
Valve structures 54 and 56 are identical and each comprises a small triangular-shaped disk made of a synthetic fuel resistant material, such as an acetal resin. Disk 60 is seated on an annular rib 62 and retained in position by a C-shaped metal snap ring 64.
Valve structures 54 and 56 are easily mounted within the pump structure by first inserting each triangularshaped disk 60 and then snapping the associated C-ring 64 in position adjacent disk 60. The tendency of C-ring 64 to expand outwardly urges ring 64 to engage with the adjacent Wall surface thereby to hold the ring in position. Cup-shaped members 36 and 38 are coaxially mounted with matching cylindrical portions fitted together. This permits one member to be rotated relative to the other member about the common longitudinal axis of pump 12 to provide any desired angular relationship between inlet nipple 20 and air nipple 16 thereby allowing adaptation of the pump to any carburetor or any engine installation.
It is to be understood that the body portions forming pump 12 may be formed with the upper cup-shaped body portion receiving a lower cup-shaped body portion in telescoping interfitting relation such as disclosed in patent application Serial Number 220,638 which matured into Patent No. 3,179,055. Further, while the fuel pump has been illustrated as utilized with a four-cycle internal combustion engine, it is to be understood that the present invention may be utilized with a two-cycle internal combustion engine and may be attached directly to the crankcase. When utilized in two-cycle operation, the spring for driving the diaphragm (spring 46 of FIGURES 2 and 3) is normally not employed as air pressure pulsations created in the crankcase by movement of the piston backward and forward provides suflicient positive pressure for driving the pump.
Referring to FIGURE 5, upper cup-shaped portion 36 has an annular extension 66 forming an inner rim. Extension 66 has an annular head or ball 68. Lower cupshaped portion 38 has an annular rim 70 with an annular lip 72 formed on its inner circumference. Beneath lip 72 is a lower annular channel or groove 74 formed in the inner wall of rim 70 and defining an inclined seat surface or shoulder 76. Body members 36 and 38 are designed so that the lower cylindrical end of body member 36 will coaxially telescope into the opened rim 70 of cup-shaped member 38 and bead 68 Will snap under annular lip 72 and be held in position by contact with the inclined seat surface 90. The interfitting of body portions 36 and 38 requires a resilience when the portions are snapped together. One material which furnishes the necessary resilience is plastic, such as, for example, an acetal resin. Annular lip 72 and bead 68 are designed such that the rim of member 38 must expand by a flowing of the plastic material to permit bead 68 to enter and snap into groove 74 against seat surface 90. Bead 68 is of a diameter slightly larger than the diameter of lip 72 so that there is a tight fit between the two because of the mismatch. It is to be understood that other types of plastics or resilient material may be employed for forming body members 36 and 38.
Constituting an important feature of this invention, cup-shaped portions 36 and 38 are formed to grip tightly marginal portion 41 of diaphragm 40 and to minimize stretching of the diaphragm upon its movement between pumping and suction strokes, particularly at the end of the pumping stroke. Lower annular rim 70 has a lower inclined seat surface or shoulder 76 forming a relatively smooth and even inclined surface at the bottom of annular rim 70. Extension 66 has a lower inclined surface 78 which extends in a direction generally parallel to shoulder 76. Surfaces 76 and 78 are flared or inclined at an angle of around 30 with respect to the horizontal axis of pump 12. Lower cup-shaped portion 38 has a ledge 80 forming the bottom of pumping chamber 42 normal to the longitudinal axis of pump 12 as shown in FIGURES 3 and 4. Again referring to FIGURES 3 and 4, depression below ledge 80 is formed by respective inlet and outlet portions 81 and 83 of pumping chamber 72. Connecting surface 78 with ledge 80 is an inclined seat surface 82 which forms a continuation of surface 76, to provide a frusto-conical inner surface. At the end of a discharge or pumping stroke, diaphragm 40 is generally flattened out against ledge 80 and merging surface 82 as shown in FIGURES 3 and 4 which minimizes stressing of the diaphragm. Surfaces 76 and 78 by being flared with respect to the horizontal axis of pump 12 result in the formation of a looped diaphragm on the suction stroke which flexes sufficiently to follow the adjacent surfaces defining pumping chamber 42 and air chamber 44 without any substantial stretching of the diaphragm. This does not tend undesirably to stress or distort the diaphragm. Thus, there is no bending of diaphraghm 40 adjacent the corner formed by surface 76 and the adjacent inner wall of lower cupshaped portion 38 at the end of a discharge stroke. On the suction stroke, the diaphragm flexes entirely in one direction to form a loop only in one direction and fits closely adjacent the adjacent inner surface of body portion 36. The lower inner edge of extension 66 is beveled at 86 so that diaphragm 40 has a smooth surface to fit against its intake or suction stroke.
In view of the above, it will be seen that the several objects of the invention are achieved of the advantageous results obtained.
As various changes could be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.
What is claimed is:
1. A pulse pump for a fuel system comprising a pair of interfiting molded plastic body members, one of said body members being cup-shaped and having an outer annular rim and an annular seat adjacent said rim, the other of said body members having an annular extension received within the annular rim of the cup-shaped member, said annular seat and said annular extension having complementary oppositely facing generally smooth and parallel surfaces, a generally circular diaphragm positioned across and having its marginal portion etxending between the oppositely facing surfaces of said annular seat and said annular extension, a fuel chamber formed on one side of the diaphragm and an air chamber formed on the opposite side of the diaphragm, each of said generally parallel surfaces sloping inwardly toward the fuel chamber from the outer periphery of the diaphragm to form an inclined seat for the marginal portion of said diaphragm, and an interfitting annular bead and groove arrangement on said annular extension and annular rim whereby said body members may be snapped together to effect the interfitting of the bead and groove arrangement and gripping of the diaphragm between the sloping surfaces of the body members, said bead and groove arrangement permitting relative rotation movement between the body members while holding the body members together in pressed relation against the diaphragm.
2. A pulse pump as set forth in claim 1 wherein a nipple is positioned on said one cup-shaped body member and an inlet and outlet are positioned on said other body member.
3. A pulse pump as set forth in claim 1 wherein said bead and groove arrangement comprises an annular bead on the outer circumference of the annular extension and a groove on the inner circumference of the annular rim adapted to receive said bead in interfitting relation.
4. A pulse pump for a fuel system, said pump comprising a pair of interfitting cup-shaped body members, one of the body members having an annular rim and an annular shoulder adjacent the rim forming a seat, the other of said body members having an annular extension telescoping within the first mentioned cup-shaped member and adapted to be disposed adjacent said annular shoulder, said annular shoulder and said annular extension having complementary oppositely facing generally smooth and even surfaces, a generally circular diaphragm sealed along a marginal portion between said oppositely facing complementary surfaces to form an air chamber with one body member and a fuel chamber with the other body member, each of said generally parallel surfaces sloping inwardly toward the fuel chamber from the outer periphcry of the diaphragm to form an inclined seat for the marginal portion of said diaphragm, said fuel chamber being defined by an inner peripheral surface of said other body member forming a smooth continuation of the contiguous inclined diaphragm seat and a transverse surface merging with said inner peripheral surface extending in a direction transversely of the common axis of said body members whereby the diaphragm fits against said peripheral and transverse surfaces at the end of a pumping stroke, an annular bead on the outer surface of the annular extension, and a recess on the inner surface of the annular rim receiving the bead and holding the body members together in pressed relation against the diaphragm, the body member forming the air chamber having a first nipple for connection to a source of air pulsations and extending outwardly therefrom away from the common axis of the body members, the body member forming the fuel chamber having inlet and outlet passages and a second nipple extending outwardly away from said common axis of the body members.
5. A pulse pump as set forth in claim 4 wherein said generally parallel surfaces and said inner peripheral surface slope inwardly at an angle of around 30 with respect to the transverse axis of the pump to form an inner frustoconical surface.
6. A pulse pump for a fuel system as set forth in claim 4- wherein said second nipple includes a portion of the fuel inlet passage and said body members are rotatable relative to each other about said common axis while the body members are held together by said annular bead and re cess, the common axis of the body members being subtantially normal to the longitudinal axis of the nipples thereby to permit the nipples to be easily connected to fuel and air sources.
References Cited by the Examiner UNITED STATES PATENTS 885,835 4/1908 Brush 103-44 X 2,905,097 9/1959 Johnson 103150 2,984,188 5/1961 Tuckey et al 103-44 DONLEY J. STOCKING, Primary Examiner. WARREN E. COLEMAN, Examiner,