US 5,707,561 AGranted

Tamper resistant carburetor needle valve adjustment limiter

AssigneeWalbro Corporation

InventorMark S. Swanson

Life of this patent

Estimating the term…

Loading patent…

Abstract

A limiter of the extent of adjustment of a fuel metering needle valve of a carburetor for an internal combustion engine. The limiter has a housing with a passage in which the head end of the needle valve is received and a cap received in the passage on the head end of the valve for rotation in unison with the valve. An arm carried by the body of the cap is engagable with a stop in the passage to limit to less than one complete revolution the extent to which the cap and needle valve can be rotated by an end user to adjust the needle valve. To provide a tamper-resistant limiter, the head of the cap is received in a bore of the housing passage with either only a slight clearance between them or an interference fit which also inhibits rotation of the valve by vibration of the operating engine on which the carburetor and limiter are utilized. Preferably, a non-circular recess in the head of the cap is constructed to receive the blade of a tool, such as a screw driver, to facilitate manually rotating the cap and the needle valve in unison within the limits provided by the arm and stop to permit only limited adjustment of the needle valve by an end user.

Claims14

Dependent claims

A limiter of the adjustment of a fuel flow valve having a shank with a head end projecting from the body of a carburetor comprising:

a housing carried by the carburetor body and having a pocket with a bore bounded by a circular and circumferentially continuous sidewall portion and opening to the exterior of the housing and receiving the head end of the valve in the pocket and generally coaxially with the circular sidewall portion of the bore, at least one stop in the pocket, and a cap having a body which is engagable with the head of the valve for rotation in unison with the valve, a head received in the bore of the housing and having a circular and circumferentially continuous sidewall peripheral portion having at least a close radial fit with the circular sidewall portion of the bore of the housing, and an arm having circumferentially spaced apart abutment surfaces engagable with the stop to limit to less than one complete revolution the extent of rotation of the cap and the valve on which it is received, and the circular sidewall of the head of the cap being generally coaxial with the axis of rotation of the shank of the valve and disposed axially outward of and overlapping the arm and the stop and axially within the circular sidewall portion of the bore.

Dependencies are inferred from the claim text.