US 3664774 A
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May 23, W' E. TUPPER ET AL 3,664,774
PRIMER PUMP Filed May 5, 1970 JOHN R. HANSON www ATTORNEYS United States Patent O 3,664,774 PRIMER PUMP Willis E. 'Iupper and John R. Hanson, Dexter, Mich., assignors to Dexter Automatic Products C0., Inc., Dexter, Mich.
Filed May 5, 1970, Ser. No. 34,691 Int. Cl. F04b 21 02, 39/10 U.S. Cl. 417-560 4 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF 'IHE INVENTION The present invention relates to an improved fuel primer pump adapted particulary, but not exclusively, for use with the fuel system of a snowmobile.
It is conventional practice to provide snowmobiles with small two-cycle gasoline engines for propulsion purposes, and it is normal practice to include in the fuel system a manually operable fuel primer pump to provide enriched fuel mixtures for starting purposes and the like. One of the problems that arises in connection with the prior art fuel systems is that when the engine is decelerated rapidly, it frequently is ilood, and therefore stalls. This results from from an undesired ow of fuel through the primer pump induced by the partial vacuum created at the carburetor when the engine is suddenly decelerated. It is known to provide check valves in the fuel system to overcome this problem, but such check 'valves are in general relatively complex, including compression spring and ball check elements, and they are not especially suitable in use, and are unnecessarily expensive.
SUMMARY OF THE INVENTION 'Ihe present invention has overcome the shortcomings of the prior art, and has provided an improved fuel primer pump which includes a relatively low cost unitary check valve element which cooperates with the plunger of the primer pump to prevent undesirable flooding of the engine.
According to one form of the present invention, a fuel primer pump is provided comprising a pump housing including an internal pump chamber extending to one end of the housing. The end of the housing has a peripheral inlet passageway and a central outlet passageway, both in communication with the pump chamber. An annular seat is provided at the inner end of the outlet passageway, and a resilient unitary valve element is positioned in engagement with the annular seat. The valve element has a tubular body portion fitted into the inner end of the outlet passageway, and a duckbill portion forms an extension thereof having a pair of resilient lips extending from the end of the tubular body portion further into the outlet passageway. The valve element also as a resilient umbrella portion extending annularly from the other end into seating engagement with the annular seat and overlying the inner end of the inlet passageway. Thus, the duckbill portion and the umbrella portion permit ow of fuel in one direction through the pump chamber, but
3,664,774 Patented May 23, 1972 prevent ow in the reverse direction. A pump plunger is mounted in the chamber in a normal position wherein its end is adjacent to the annular seat urging the umbrella portion against the annular seat so as to prevent communication between the inlet and outlet passageways. The pump plunger can be moved away from the valve element to create a suction pressure in the chamber to induce flow of fluid around the umbrella portion into the chamber, and on the reverse movement of the plunger the fluid in the chamber can be discharged out of the outlet passageway between the resilient lips of the duckbill portion. By virtue of this construction and arrangement, if the associated internal combustion engine is decelerated rapidly, the low pressure condition existing in the carburetor will be ineffective to induce ow of fuel to the carburetor via the primer pump, because the pump plunger seated against the umbrella portion will serve to prevent flow of fuel through the pump chamber.
Thus, it is an object of the present invention to provide an improved primer pump for use with internal combustion engines.
Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawing forming a part of this speciiication wherein like reference characters designate corresponding parts in the several views.
BRIEF DESCRIPTION OF THE DRAWING FIG. l illustrates partially in longitudinal section a primer pump embodying the present invention, and illustrates schematically a portion of the fuel system with which the primer pump is used;
FIG. 2 is a fragmentary view showing the action of the valve element of the pump when the pump plunger is moi/ed in one direction away from its normal position; an
FIG. 3 is a view similar to FIG. 2, but illustrating the action of the valve element when the pump plunger is moved in the opposite direction toward its normal position.
DESCRIPTION OF THE PREFERRED EMBODIMENT Before explaining the persent invention in detail, it is to be understood that the infvention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.
Referring now to the drawing, the invention will be described in greater detail. As there shown, the fuel primer pump 10 is mounted in a panel 12 and is connected as part of a fuel system 14. The latter includes a gasoline tank 116 a carburetor 18, a main fuel line 20 extending from the gasoline tank 16 to the carburetor 18, a supply line 22"in communication with the gasoline tank 16 via the line 20 and connected at the other end to the fuel inlet .tting 24 of the primer pump 10. A fuel outlet fitting 26 is connected to the fuel line 28 which communicates with the carburetor 18 in a conventional manner to permit the introduction of a desired enriched mixture of fuel to the associated internal combustion engine (not shown).
The pump primer 10 has a pump housing 30 which includes the cylinder portion 32 and the header or cap portion 34. The header or cap portion 34 closes the one end of the cylinder portion 32 and includes a peripheral inlet passageway 36 and a central outlet passageway 3-8, both of which are in communication with the internal chamber 40 defined within the housing 30. A pump plunger 42 including the piston portion 44, the rod portion 46 and the handle portion 48 is mounted so that the rod portion extends from the other end of the housing 30 and the piston portion is in sealing engagement with the internal bore of the housing 30, by means of the sealing or Oi-ring 50. A compression spring 52 is operatively positloned between the piston portion 44 and the other end of the housing 30 so as to urge the plunger to the one end of the housing 30, as is shown in lFIG. l.
The inner end of the outlet passageway 38 formed in the header member 34 defines an inwardly facing annular seat 54, and a resilient unitary valve element 5-6 is seated on the inner face of the annular seat. The valve element 56 includes a central portion 58 which extends into the outlet passageway 38 and is interlocked with the annular shoulder 60 of the passageway so as to prevent axial displacement of the valve element in the passageway 38. The valve element 38 includes the duckbill portion 62 which has a pair of resilient lips 64 forming extensions of the cylinder portion 58, and they are adapted to permit flow of fuel out of the passageway 58 as shown in FIG. 3, and to check ow of fuel in the reverse direction. The valve element 38 also has an umbrella portion 66 which is seated on the inner face of the annular seat 54 and which overlies the inlet passageway 36 and the annular passageway 68 in communication with inlet passageway 36.
By virtue of this arrangement, when the plunger 42 is manually moved toward the other end of the housing 30, the umbrella portion 66 will be free to deflect to the position shown in FIG. 2 to permit fuel to enter through the inlet fitting 24 and to ow through the inlet passageway 36 to the interior of the chamber l40. Thereafter, when the plunger is moved toward the other end, as indicated in FIG. 3, the umbrella portion will be returned to a position shown in PIG. 3, preventing return flow of fuel through passageway 38, but the lips 64 of the duckbill portion 62 will then separate to permit discharge of the fuel through the outlet passageway 38 and the litting 26. When the pump plunger 42 is in its normal position shown in FIG. 1 wherein it is adjacent to the annular seat 54 and is urged against the umbrella portion 66, it will prevent communication between the inlet and outlet passageways 36 and 38, thereby preventing flow of fuel from the pump during such time when a pressure drop or partial vacuum is created in the carburetor. Thus, undesired ooding of the engine which will cause stalling is prevented. This is accomplished by a relatively simple primer pump which includes a simple, trouble free and relatively low cost check valve element.
It is claimed:
1. A primer pump comprising a pump housing providing an internal chamber extending to one end of the housing, said one end deiining a peripheral inlet passageway and a central outlet passageway in communication with said chamber and an annular seat at the inner end of the outlet passageway, a resilient unitary valve element positioned in engagement with said annular seat, said valve element having a tubular body portion extending into the inner end of said outlet passageway, a duckbill portion having a pair of resilient lips extending from one end of said tubular body portion further into said outlet passageway and a resilient umbrella portion extending annularly from the other end of said tubular body portion with its inner periphery in seating engagement with said annular seat and its outer periphery extending over the inner end of said inlet passageway, and a pump plunger in said chamber in a normal position wherein its end is adjacent to said annular seat pressing said umbrella portion against said annular seat so as to prevent communication between said inlet and outlet passageways, said pump plunger being responsive to an applied force in one direction to move away from said valve element to create a pressure drop in said chamber at said inlet passageway to induce flow of fluid around said umbrella portion into said chamber and being responsive of an applied force in the other direction to return to said normal position to discharge the fluid in said chamber between said resilient lips and through said outlet passageway.
2. The primer pump that is delined in claim f1, wherein said tubular body portion and said outlet passageway have cooperating means retaining said tubular body portion against axial displacement in said outlet passageway.
3. The primer pump that is defined in claim f1, wherein said pump plunger includes a rod projecting from the other end of said housing for manually applying said force to move the pump plunger away from said valve element.
4. The primer pump that is defined in claim 3, wherein a compression spring is mounted between said other end and said plunger for applying said force in the other direction to return said plunger to its normal position.
References Cited UNITED STATES PATENTS 3,527,551 9/1970 Kutik et al 417-571 X 2,424,595 7/1947 Warren 417-571 X 3,159,176 l2/1964 Russell et al. 137-493.l
FOREIGN PATENTS 560,076 3/ 1957 Italy 417-560 875,142 4/ 1953 Germany 417--479 `CARLTON R. CROYLE, Primary Examiner R. E. GLUCK, Assistant Examiner U.S. Cl. X.R.