Multiple heat automatic choke

Claim 2

An automatic choke system for use with a carburetor having an air/fuel induction passage, an unbalance mounted, air movable choke valve mounted for variable movement across the passage to control airflow 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 first and second self-limiting output temperature heater devices operably associated with the choke valve to effect opening of the choke valve by varying degrees in response to increases in temperature of the heater devices up to their individual output limits, the first heater device being operable at all times, and control means to render the second heater device operable above a predetermined ambient temperature level.

Claim 3

A choke system as in claim 1, the control means comprising a thermostatically responsive on-off switch means.

Claim 4

A choke system as in claim 1, the heater devices comprising positive temperature coefficient (PTC)elements characterized by increasing internal impedance with increasing temperatures up to their limits limiting further current flow and heat buildup.

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 airflow 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 first normally operable and second intermittently operable self-limiting output temperature, positive temperature coefficient (PTC) heater devices located adjacent the spring means operable to transfer their heat output thereto when operable up to their limit to reduce the choke valve closing force of the spring means and permit opening of the choke valve by airflow through the passage against it, and other means to render the second heater device operable.

Claim 6

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 airflow 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 first normally operable and second intermittently operable self-limiting output temperature, positive temperature coefficient (PTC) heater devices located adjacent the spring means operable to transfer their heat output thereto when operable up to their limit to reduce the choke valve closing force of the spring means and permit opening of the choke valve by airflow through the passage against it, and other means to render the second heater device operable.

Claim 7

A choke system as in claim 4, the other means comprising temperature sensitive means rendering the second heater device operable above a predetermined ambient temperature level to begin transferring its heat output to the spring means.

Claim 8

A choke system as in claim 5 including a heat sink secured to the second heater device for uniformly radiating the heat of the second heater device to the spring means.

Claim 9

A choke system as in claim 5, the heater devices comprising positive temperature coefficient heater elements characterized by increasing internal impedance with increases in internal temperature up to their limits limiting further current flow and heat buildup.

Claim 10

A two phase automatic choke system for use with a carburetor having an air/fuel induction passage open at one end and adapted to be connected to an engine intake manifold at the other end for subjecting the passage to varying manifold vacuum, the passage having a throttle valve mounted for a variable movement between positions opening and closing the passage to control air/fuel flow through it, the choke system including an unbalance mounted, air movable choke valve mounted anterior of the throttle valve for variable movement across the passage to control airflow towards the throttle valve, 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, first power means sensitive to engine manifold vacuum for moving the choke valve towards an open position in opposition to the spring means, and means supplemental to the first power means for effecting subsequent movement of the choke valve towards a position more open than the position effected by the first power means, the supplemental means including first and second electrically energized positive temperature coefficient (PTC) heater devices located adjacent the bimetallic spring means and operable to transfer their heat output to the spring means to reduce its choke valve closing force and permit opening of the choke valve by airflow through the passage against it, the first heater device being operable at all times, and temperature responsive means operable above a predetermined ambient air temperature to energize the second heater device, the internal resistance of the PTC heaters above a second predetermined temperature level restricting current flow and heat output to thereby eliminate the need for temperature responsive cut out switch means to deenergize the heater elements above the second predetermined temperature level.

Claim 11

A two phase automatic choke system for use with a carburetor having an air/fuel induction passage open at one end and adapted to be connected to an engine intake manifold at the other end for subjecting the passage to varying manifold vacuum, the passage having a throttle valve mounted for a variable movement between positions opening and closing the passage to control air/fuel flow through it, the choke system including an unbalance mounted, air movable choke valve mounted anterior of the throttle valve for variable movement across the passage to control airflow towards the throttle valve, 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, first power means sensitive to engine manifold vacuum for moving the choke valve towards an open position in opposition to the spring means, and means supplemental to the first power means for effecting subsequent movement of the choke valve towards a position more open than the position effected by the first power means, the supplemental means including first and second electrically energized positive temperature coefficient (PTC) heater devices located adjacent the bimetallic spring means and operable to transfer their heat output to the spring means to reduce its choke valve closing force and permit opening of the choke valve by airflow through the passage against it, the first heater device being operable at all times, and temperature responsive means operable above a predetermined ambient air temperature to energize the second heater device, the internal resistance of the PTC heaters above a second predetermined temperature level restricting current flow and heat output to thereby eliminate the need for temperature responsive cut out switch means to deenergize the heater elements above the second predetermined temperature level.

Claim 12

A two phase automatic choke system for use with an internal combustion engine carburetor having an air/fuel induction passage open at one end and adapted to be connected to an engine intake manifold at the other end for subjecting the passage to varying manifold vacuum, the passage having a throttle valve rotatably mounted across the passage adjacent the lower end for a variable movement between positions opening and closing the passage to control air/fuel flow through it, the choke system including an unbalance mounted, air movable choke valve rotatably mounted across the passage adjacent the upper end for variable opening and closing movements to control airflow towards the throttle valve, a thermostatically responsive spring coil operably connected to the choke valve and normally urging the choke valve towards a closed position with a force increasing with decreases in the temperature of the coil from a predetermined level, first power means operably connected to the choke valve and sensitive to engine manifold vacuum for moving the choke valve from an initially closed position towards an open position in opposition to the coil and in response to operation of the engine from a start to a running conditon, the first power means including a vacuum operated movable piston means, and a first heat source transferring engine heat to the coil and comprising a hot air containing duct operably connected from the engine exhaust system to the coil for warming the coil to reduce its choke valve closing force, and supplemental second and third electrically controlled, temperature responsive heat means in a parallel and series flow arrangement, respectively, with the first power means heat source and effecting subsequent movement of the choke valve towards a position more open than the position effected by the first power means alone, the supplemental means including a source of electrical energy, first and second positive temperature coefficient (PTC) heater device located adjacent the bimetallic spring means and operable to transfer their heat output to the coil to reduce its choke closing force and permit opening of the choke valve by airflow through the passage against it, means connecting the first heater device to the source at all times for concurrent operation with the first power means, and temperature responsive switch means operable above a predetermined ambient air temperature to connect the source to the second heater device to energize the second heater device, the internal resistance of the first and second heater devices above a predetermined heater temperature level increasing to a level restricting further heAt buildup beyond a predetermined level.

Claim 13

A two phase automatic choke system for use with an internal combustion engine carburetor having an air/fuel induction passage open at one end and adapted to be connected to an engine intake manifold at the other end for subjecting the passage to varying manifold vacuum, the passage having a throttle valve rotatably mounted across the passage adjacent the lower end for a variable movement between positions opening and closing the passage to control air/fuel flow through it, the choke system including an unbalance mounted, air movable choke valve rotatably mounted across the passage adjacent the upper end for variable opening and closing movements to control airflow towards the throttle valve, a thermostatically responsive spring coil operably connected to the choke valve and normally urging the choke valve towards a closed position with a force increasing with decreases in the temperature of the coil from a predetermined level, first power means operably connected to the choke valve and sensitive to engine manifold vacuum for moving the choke valve from an initially closed position towards an open position in opposition to the coil and in response to operation of the engine from a start to a running conditon, the first power means including a vacuum operated movable piston means, and a first heat source transferring engine heat to the coil and comprising a hot air containing duct operably connected from the engine exhaust system to the coil for warming the coil to reduce its choke valve closing force, and supplemental second and third electrically controlled, temperature responsive heat means in a parallel and series flow arrangement, respectively, with the first power means heat source and effecting subsequent movement of the choke valve towards a position more open than the position effected by the first power means alone, the supplemental means including a source of electrical energy, first and second positive temperature coefficient (PTC) heater device located adjacent the bimetallic spring means and operable to transfer their heat output to the coil to reduce its choke closing force and permit opening of the choke valve by airflow through the passage against it, means connecting the first heater device to the source at all times for concurrent operation with the first power means, and temperature responsive switch means operable above a predetermined ambient air temperature to connect the source to the second heater device to energize the second heater device, the internal resistance of the first and second heater devices above a predetermined heater temperature level increasing to a level restricting further heAt buildup beyond a predetermined level.

Claim 14

A choke system as in claim 9 including a heat sink secured to the second PTC device for uniformly radiating the heat of the second PTC device to the coil, the second PTC device being larger than the first device and providing a greater heat output.

Claim 15

A choke system as in claim 10, the heat sink comprising a thin metallic disc secured to the coil mounting means between the second PTC device and coil.

Claim 16

A choke system as in claim 9, including a housing enclosing the PTC heater devices and coil, an insulating gasket dividing the housing into a first chamber and a second chamber, the first chamber having an inlet and outlet for the hot air duct, the second chamber containing the heater devices and coil and containing an aperture for flow of hot air through the gasket in a path to indirectly heat the coil, the PTC heater devices being located in the housing on the side of the coil opposite to the gasket to receive heat from a direction opposite to that from the gasket.