Carburetor air-fuel mixture adjustment assembly and tools

Patent metadata

Field	Value
Publication number	US-10072615-B2
Application number	US-201615337349-A
Country	US
Kind code	B2
Filing date	Oct 28, 2016
Priority date	Nov 6, 2015
Publication date	Sep 11, 2018
Grant date	Sep 11, 2018

Abstract

A carburetor with a fuel adjustment tamperproof valve assembly and specialized tools for adjusting the valve assembly. A needle valve is received in a recess in a carburetor body with a passage open to the exterior of the body and a cylindrical surface of the passage. A valve head with a cylindrical exterior surface is received in the passage with a slight clearance between them. The specialized tools are engageable with the head to adjust the valve by rotating it.

First claim

The invention claimed is:

1. A carburetor for an engine comprising:
a body having a mixture passage for supplying an air-fuel mixture to an operating engine;
a valve receptacle in the body having a passage with a cylindrical surface and the passage open to the exterior of the body;
a valve rotatably received in the receptacle in the body for adjusting the air-to-fuel ratio of the air-fuel mixture and having a head with an exterior cylindrical surface and an outer end face received in the passage with the outer end face disposed axially wholly within the passage and with a slight clearance between the head cylindrical exterior surface and the passage cylindrical surface of not more than 2.5 mm and the outer end face of the head being disposed axially inboard of or flush with the outboard end of the passage, wherein the valve further comprises a cylindrical pocket in the valve head which is at least substantially concentric with the exterior cylindrical surface of the valve head.

2. The carburetor of claim 1 wherein the maximum diameter of the cylindrical passage is 6.70 mm and the minimum diameter of the exterior cylindrical surface of the valve head is 4.95 mm.

3. The carburetor of claim 1 wherein the cylindrical pocket in the valve head has a diameter in the range of 3.00 to 3.70 mm.

4. The carburetor of claim 1 wherein the cylindrical pocket in the valve head has a circumferentially continuous and uninterrupted surface which is concentric with the exterior cylindrical surface of the head.

5. The carburetor of claim 1 wherein the valve head is solid, the exterior cylindrical surface of the valve head is at least substantially uninterrupted throughout, and the outer end face of the valve head is disposed axially inboard at least 1 mm from the outboard end of the cylindrical surface of the passage.

6. The carburetor of claim 1 wherein the valve further comprises a tapered tip at an end of the valve distal from the cylindrical head and between them a cylindrical threaded portion coaxial with the tip and engageable with a complementary threaded portion of the receptacle.

7. A tool for rotatably adjusting a valve with a head having an exterior cylindrical surface and a pocket in the head with an inner cylindrical surface with the valve received in a receptacle of a carburetor with a passage of the receptacle open to the exterior of the carburetor and the passage having a cylindrical surface with the head received in the passage, the tool comprising:
a tubular shank;
at least two collet fingers carried by the shank and each extending generally axially to a free end having a generally circumferentially extending portion and collectively the circumferentially extending portions have an outside diameter smaller than the diameter of the inside cylindrical surface of the pocket of the head of the valve;
a follower surface on at least a portion of the free end of each finger and tapering generally radially and axially inward relative to the outer circumferential surface portion of its associated finger;
a cam having a cam surface complementary to and engageable with the follower surfaces of the finger;
a rod received in the tubular shank and adjacent one end attached to the cam and adjacent another end having a threaded portion extending generally axially outwardly of the tubular shank;
a knob carrying complementary threads engaged with at least some of the threads of the threaded portion of the rod; and
the knob is rotatable in one direction relative to the rod to move the cam surface into engagement with the followers to move the end portions of the fingers generally radially outward into firm engagement with at least a portion of the inner cylindrical surface of the pocket of the head when the end portion of each finger is received in the pocket of the head so that rotation of the fingers in unison with the cam rotates the valve to adjust an air-to-fuel ratio of an air-fuel mixture supplied by the carburetor to an operating engine, and rotation of the knob relative to the shank in a direction opposite to one direction of rotation of the knob permits the fingers to move generally radially inward to release the fingers from firm engagement with the inner cylindrical surface of the pocket of the valve head so that the fingers can be generally axially removed from the valve head without rotating the valve.

8. The tool of claim 7 further comprising a slot between adjacent fingers and a tab or pin carried by and projecting generally radially outward of the rod and into the slot to limit rotation of the rod relative to the tubular shank.

9. The tool of claim 7 which also comprises a handle attached to the shank for manually gripping the handle while manually rotating the knob.

10. The tool of claim 7 wherein the knob bears on one end of the shank or the handle when being rotated to move the cam to engage the fingers and move the fingers generally radially outward into firm engagement with the inner cylindrical surface of the pocket of the head of the valve.

11. The tool of claim 7 wherein the cam has a frusto-conical cam surface engageable with the follower surfaces of the fingers and the maximum diameter of the cam is smaller than the diameter of the inner cylindrical surface of the pocket of the head of the valve.

12. A tool for rotatably adjusting a valve with a head having an exterior cylindrical surface and received in a receptacle of a carburetor with a passage of the receptacle open to the exterior of the carburetor and having a cylindrical surface and the head is received in passage, the tool comprising:
a shank having a cylindrical threaded portion;
at least two collet fingers carried by the shank adjacent the threaded portion and each extending generally axially to a free end distal from the threaded portion and at least adjacent the free end having a generally circumferentially extending portion and collectively the circumferentially extending portions have an outside diameter smaller than an inside diameter of the passage of the receptacle;
an annular collar having internal threads complementary with and engaging the threads of the cylindrical portion of a shank and adjacent one end of the collar, a cam surface inclined to a longitudinal axis of the collar and engageable with a complementary follower surface on an exterior portion of each of the fingers and axially spaced from the ends of the fingers; and
the cam and follower surfaces are configured so that rotation in one direction of the collar relative to the shank moves the cam surface into engagement with the follower surfaces to move portions of an internal surface of each finger adjacent its associated free end into firm engagement with the exterior cylindrical surface of the head of the valve when the end portion of each finger is received between the cylindrical head and the cylindrical surface of the passage of the receptacle so that rotation of the collar and fingers in unison rotates the valve to adjust an air-to-fuel ratio of an air-fuel mixture supplied by the carburetor to an operating engine, and rotation of the collar relative to the shank in a direction opposite to the one direction of rotation retracts the cam surface of the collar relative to the follower surfaces of the fingers to release the fingers from firm engagement with the exterior surface of the valve head so that they can be generally axially removed from the valve head and the passage without rotating the valve.

13. The tool of claim 12 wherein the circumferentially extending portions have an inside diameter larger than the diameter of the exterior cylindrical portion of the head of the valve.

14. The

Assignees

• Walbro Llc

Inventors

• Pattullo George M

Classifications

• B25B13/48

  for special purposes · CPC title

• B25B23/105

  the gripping device being an integral part of the driving bit · CPC title

• B01F2215/0088

  Operations & Transport · mapped topic

• B25B23/103

  for gripping threaded studs · CPC title

• B25B27/0035

  for motor-vehicles (wrenches for mounting or dismounting wheels B60B29/003) · CPC title