Carburetor automatic choke construction

Claim 2

An automatic choke system for use with a carburetor having an air/fuel induction passage and an unbalance mounted, air movable, choke valve mounted for variable movement across the passage to control air flow through the passage, thermostatic spring means operably connected to the choke valve urging the choke valve towards a closed position with a force increasing as a function of decreases in the temperature of the spring means from a predetermined level, and a self-limiting output temperature heater device located adjacent the spring means operable to transfer its heat output thereto up to its limit to reduce the choke valve closing force of the spring means and permit opening of the choke valve by air flow through the passage against it, including means rendering the heater device operable above a predetermined ambient temperature level to begin transferring its heat output to the spring means, and a heat sink secured to the heater device for uniformly radiating the heat of the heater device to the spring means.

Claim 3

A choke system as in claim 1, the heat sink comprising a thin metallic disc secured to the spring means mounting means between the heater device and spring means.

Claim 4

An automatic choke system for use with a carburetor having an air/fuel induction passage and an unbalance mounted, air movable, choke valve mounted for variable movement across the passage to control air flow through the passage, thermostatic spring means operably connected to the choke valve urging the choke valve towards a closed position with a force increasing as a function of decreases in the temperature of the spring means from a predetermined level, a positive temperature coefficient (PTC) heater device located adjacent the bimetallic spring means and operable above a predetermined ambient temperature level to transfer its heat output to the spring means to reduce choke valve closing force of the spring means and permit opening of the choke valve by air flow through the passage against it, the internal impedance off the PTC device increasing with increases in internal temperature of the PTC device so as to above a predetermined PTC temperature level minimize current flow and heat output, and a heat sink secured to the PTC device for uniformly radiating the heat of the PTC device to the spring means.

Claim 5

An automatic choke system for use with a carburetor having an air/fuel induction passage and an unbalance mounted, air movable, choke valve mounted for variable movement across the passage to control air flow through the passage, thermostatic spring means operably connected to the choke valve urging the choke valve towards a closed position with a force increasing as a function of decreases in the temperature of the spring means from a predetermined level, a positive temperature coefficient (PTC) heater device located adjacent the bimetallic spring means and operable above a predetermined ambient temperature level to transfer its heat output to the spring means to reduce choke valve closing force of the spring means and permit opening of the choke valve by air flow through the passage against it, the internal impedance off the PTC device increasing with increases in internal temperature of the PTC device so as to above a predetermined PTC temperature level minimize current flow and heat output, and a heat sink secured to the PTC device for uniformly radiating the heat of the PTC device to the spring means.

Claim 6

A choke system as in claim 3, the heat sink comprising a thin metallic disc secured to the spring means mounting means between the PTC device and spring means.