# US 4,396,558 A · Automatic choke

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- Number: US 4,396,558 A
- Document ID: US4396558A
- Status: Granted
- Kind: A
- Application number: 06/335,138
- Filed: 1981-12-28
- Granted: 1983-08-02
- Earliest claimed: 1980-02-28
- Assignees: Ford Motor Company
- Inventors: John F. Brunning
- Web page: https://patentgrep.com/patent/US4396558A

## CPC

- F02M 1/043: {Auxiliary carburetting apparatus controlled by rotary sliding valves}
- F02M 9/106: {Pneumatic or hydraulic control}
- F02M: SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF

## Abstract

An automatic choke for a carburetor comprises a fuel enrichment valve (59, 60) for controlling the flow of fuel into a carburetor, a first operating lever (54) movable by a temperature sensitive element, e.g. a bimetallic coil spring, into engagement with an end stop (100); a second operating lever (57) for opening and closing the fuel enrichment valve (59, 60); a resilient connection, e.g. a coaxial coil spring (64), between the first and second levers (54, 57) by which the first lever moves the second lever to open the fuel enrichment valve at low temperatures; and an override lever (72) operable by a vacuum control device (73-80) to move the second lever against the bias of the resilient connection to close the fuel enrichment valve at low temperatures and low engine loads.

## Claims

### Claim 1

An automatic choke for a carburetor comprising a fuel enrichment valve for controlling the flow of fuel into a carburetor; a temperature-sensitive element; a first operating lever movable by the temperature-sensitive element into engagement with an end stop at low temperatures; a second operating lever for opening and closing the fuel enrichment valve and movable with the first operating lever so as to open the fuel enrichment valve as the first operating lever moves towards the end stop; and an override lever operable by a vacuum operated control device in response to vacuum in the manifold of the engine to which the carburetor is attached to effect closure of the fuel enrichment valve, characterised in that the first operating lever moves the second operating lever through a resilient connection to open the fuel enrichment valve at low temeratures, and in that the override lever moves the second operating lever against the bias of the resilient connection to close the fuel enrichment valve at low temperatures.

### Claim 2 (depends on 1)

An automatic choke according to claim 1 wherein the resilient connection comprises a spring.

### Claim 3 (depends on 2)

An automatic choke according to claim 2 wherein the first and second operating levers are mounted coaxially and the spring comprises a coaxial coil spring.