US 3730495 A
An easily serviceable carburetor accelerator pump unit incorporates a shield rolled over the outer rim of a rolling diaphragm and having a plurality of inwardly extending members to limit upward travel of a plunger head carried by the diaphragm.
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Description (OCR text may contain errors)
United States Patent 1191 Elam 1451 May 1, 1973 CARBURETOR ACCELERATOR PUMP Charles F. Elam, Rochester, NY.
General Motors Detroit, Mich.
Filed: July 15,1971
Appl. No.: 162,928
US. Cl ..261/34 A, 92/98 D, 92/99, 417/471 Int. Cl ..F02m 7/08 Field of Search ..261/34 A; 92/98 D, 92/99; 417/471  References Cited UNITED STATES PATENTS 2,035,636 3/1936 Chandler ..26l/34 A Schweiss ..26l/34 A Carlson ...261/34 A Ferguson ..92/98 D Bowerman et a1 ..92/98 D Primary Examiner--Tim R-. Miles Attorney-J. L. Carpenter et a1.
ABSTRACT v An easily serviceable carburetor accelerator pump unit incorporates a shield rolled over the outer rim of a rolling diaphragm and having a plurality of inwardly extending members to limit upward travel of a plunger head carried by the diaphragm.
2 Claims, 1 Drawing Figure PATENTEDIAY Hm INXENTOR. Char/e5 1'' 6/021:
. ATTORNEY CARBURETOR ACCELERATOR PUMP A prior art carburetor accelerator pump proposal 7 uses a rolling diaphragm as a pumping member but does not provide an easily serviceable assembly because the rolling diaphragm is secured in the accelerator pump well only during final carburetor assembly. In addition, the prior art proposal does not provide means for limiting unrolling of the diaphragm to prevent rupture of the diaphragm material.
This invention obviates these disadvantages by providing a separate shield member which surrounds the diaphragm and is secured to its outer rim. The shield member is pressed into the accelerator pump well where it is retained during normal operation but from which it may be extracted for service replacement. The upper end of the shield has a plurality of inwardly extending members which overlie the plunger head to limit upward movement of the plunger head and prevent rupture of the diaphragm.
The details as well as other objects and advantages of this invention are set forth below and are shown in the drawing which is an elevational view of a carburetor, shown partially in section to depict the details of the accelerator pump structure.
Referring to the drawing, a carburetor 10 has a mixture conduit 12 in which a throttle 14 is disposed on a shaft 16. A throttle lever 18 secured on shaft 16 actuates a link 20 which, upon throttle opening movement, causes clockwise movement of an intermediate lever 22. A cam surface 24 on intermediate lever 22 drives a pump lever 26 counterclockwise to depress a pump rod 28.
The spherically contoured lower end 30 of rod 28 is received in a spherical depression 32 in an accelerator pump plunger head 34. The movable inner rim 36 of a rolling diaphragm 38 is secured about a land 40 of plunger head 34. The stationary outer rim 42 of rolling diaphragm 38 is retained by a rolled-over portion 44 of a cylindrical shield 46. The upper end of shield 46 has three inwardly extending members 48 which overlie plunger head 34 as shown in the drawing.
Shield 46, with diaphragm 38 and plunger head 34 assembled thereto, is pressed into and retained in an accelerator pump well 50 formed in the fuel bowl portion 52 of carburetor 10. The lower end 44 of shield 46 abuts an annular ledge 54 formed in accelerator pump well 50.
A cross passage 56 extends from the bottom of well 50, past a pump inlet passage 58, to pump outlet passage 60. As the throttle is closed, the link and lever mechanism connection to throttle l4 permits upward movement of plunger head 34 by a biasing spring 62, and fuel is drawn into well 50 from fuel bowl 52 through passage 58, past a check valve 64, and through cross passage 56. As the throttle is opened, the downward movement of plunger head 34 caused by the link and lever mechanism discharges fuel from well 50 into cross passage 56, a vent ball check valve 65 closes the vapor vent passage 66 extending through plunger head 34, inlet ball check valve 64 is seated, a discharge ball check valve 67 is lifted, and fuel is discharged through an outlet tube 68 and discharge orifices 70 and 72 into mixture conduit 12. (It will be appreciated that the end 74 of cross passage 60 is plugged after drilling of cross passage 56.)
The easy serviceability of the accelerator pump assembly is evident from the foregoing. Should the accelerator pump diaphragm malfunction, the air horn section 76 of the carburetor 10 may be removed from the fuel bowl section 78, the shield-diaphragm-plunger head assembly withdrawn from accelerator pump well 50, and a replacement shield-diaphragm-plunger head assembly inserted without necessitating substantial disassembly of the carburetor or the accelerator pump mechanisms.
1. A carburetor accelerator pump assembly comprismg:
a rolling diaphragm having a stationary outer rim and a movable inner rim,
a plunger head secured to the inner rim of said diaphragm,
and a cylindrical shield surrounding said diaphragm; said shield having one end rolled radially inwardly over and retaining the outer rim of said diaphragm, said shield further having a member at the other end extending radially inwardly to overlie and retain said plunger head.
2. An accelerator pump for a carburetor having a fuel bowl, means defining a cylindrical accelerating well having an annular radially inwardly extending ledge formed therein, means for conveying fuel from said bowl to said well, a mixture conduit, means for conveying fuel from said well to said mixture conduit, and an accelerator pump actuating member, said accelerator pump comprising:
a rolling diaphragm disposed in said well and having a stationary outer rim disposed adjacent said ledge and having a movable inner rim,
a cylindrical shield received in said well and surrounding said diaphragm, said shield having a lower end rolled radially inwardly over and retaining said stationary rim of said diaphragm, said lower end abutting said annular ledge formed in said well, I
a plunger head disposed within said well and secured to said inner rim of said diaphragm,
and spring means biasing said plunger head upwardly in said well, said plunger head being operable against the bias of said spring means by said actuating member,
the upper end of said shield further having a plurality of radially inwardly extending members overlying said plunger head to limit upward movement of said plunger head.