Carburetor with combined choke pulldown and fast idle cam kickdown apparatus

Claim 2

A carburetor having an air/fuel induction passage open at one end to air at essentially atmospheric pressure and connected at its opposite end to an engine intake manifold to be subject to the changing vacuum levels therein, the one end having a choke valve rotatably mounted for movement across the passage between a closed air choking position and an open inoperative position, and a throttle valve rotatably mounted posterior of the choke valve for movement across the passage between a normal essentially closed engine idle speed position and beyond towards a wide open throttle position to control the quantity of air/fuel mixture flow through the passage, an abutment means rotatable with the throttle valve, a rotatable fast idle cam having a high cam step projecting radially from the cam axes for engagement at times by the abutment means during movement of the throttle valve in a closing direction to stop the throttle valve in a more open position than the idle speed position to increase mixture flow to the manifold, the cam also having a second cam step of lesser radial extent engagable with the abutment means at other times as a function of the rotative position of the cam to stop the throttle valve in a less open position than the high cam step position, the cam being rotatable by gravity towards an inoperative position upon disengagement of the abutment means with the cam step permitting closure of the throttle valve towards the normal idle speed position, rotatable lever means secured to the choke valve, interconnecting means operably connecting the lever means and fast idle cam and having a portion extending into the path of rotative movement of the fast idle cam towards the inoperative position to stop the cam rotation, means to rotate the lever means, and a single vacuum actuated member engagable with the interconnecting means and cam and operable immediately upon the engine attaining sustained operation after the initial cold engine cranking operation while the abutment means is engaged with the fast idle cam high step to automatically and sequentially first effect movement of the lever means to crack open the choke valve from a closed engine cranking position and subsequently rotate the fast idle cam to a position disengaging the abutment means from the high cam step and engaging the abutment means with the second cam step to lean and reduce the mixture flow to the engine to improve emissions while minimizing engine stalling.

Claim 3

A carburetor as in claim 1, including a shaft mounting the lever means, means rotatably mounting the fast idle cam and the interconnecting means on the shaft, and a cam member connected to the vacuum actuated member and progressively engagable with the interconnecting means and cam to first operably rotate the lever means to open the choke valve and then rotate the cam off the high cam step engagement with the abutment means.

Claim 4

A carburetor as in claim 2, the interconnecting means comprising a bellcrank-like member havine a one-way interconnection with the lever means permitting free movement of the lever means in a choke valve opening direction.

Claim 5

A carburetor as in claim 2, the vacuum actuated member comprising a vacuum servo having linkage means connecting the servo and cam member, and a vacuum line connecting the servo to the engine intake manifold vacuum.

Claim 6

A carburetor as in claim 2, the cam member comprising an elongated slide member movable laterally of the axis of the shaft and having a pair of first and second spaced laterally projecting cam portions, the first portion being engagable with the interconnecting means to rotate the same, the second portion being engagable with the cam to rotate the cam.

Claim 7

A carburetor as in claim 5, the cam portions projecting from opposite sides of the slide member into separate alignment with cam follower portions on the interconnecting means and cam.

Claim 8

A carburetor as in claim 3, including means securing the shaft to a thermostatically responsive spring means urging the shaft and lever means in a choke valve closing direction upon decreases in temperature below the engine normal operating temperature level to effect movement of the fast idle cam by the lever means to permit repositioning of the fast idle cam to its high cam step engagement position with the abutment means for engine starting purposes.

Claim 9

A carburetor having an air/fuel induction passage open at one end to air at essentially atmospheric pressure and connected at its opposite end to an engine intake manifold to be subject to the changing vacuum levels therein, the one end having a choke valve rotatably mounted for movement across the passage between a closed air choking position and an open inoperative position, and a throttle valve rotatably mounted posterior of the choke valve for movement across the passage between a normal essentially closed engine idle speed position and beyond towards a wide open throttle position to control the quantity of air/fuel mixture flow through the passage, an abutment means rotatable with the throttle valve, a rotatable fast idle cam having a high cam step projecting radially from the cam axes for engagement at times by the abutment means during movement of the throttle valve in a closing direction to stop the throttle valve in a more open position than the normal idle speed position to increase mixture flow to the manifold, the cam also having a second cam step of lesser radial extent engagable with the abutment means at other times as a function of the rotative position of the cam to stop the throttle valve in a less open position than the high cam step position, the cam being rotatable by gravity towards an inoperative position upon disengagement of the abutment means with the cam step permitting closure of the throttle valve towards the normal idle speed position, a shaft, rotatable lever means secured on the shaft for rotation therewith and connected to the choke valve, the shaft rotatably mounting the fast idle cam and a bellcrank cam member, the cam member having axially spaced projecting portions providing separate one-way interconnections with the lever means and fast idle cam permitting free rotation of the lever means in a choke valve opening direction and the fast idle cam in a direction moving the high cam step towards engagement with the abutment means, both the cam member and cam having separate cam follower surfaces, the cam member one-way interconnection with the fast idle cam comprising a portion extending into the path of rotative movement of the fast idle cam towards the inoperative position permitting stopping of rotation of the cam in this direction, thermostatic spring means to rotate the shaft and lever means, and vacuum mechanical control means operable in response to the engine attaining sustained operation after a cold engine cranking operation while the abutment means is engaged with the fast idle cam high step to automatically and progressively first move the lever means to crack open the choke valve from an initial closed position and subsequently rotate the fast idle cam to a position disengaging the abutment means from the high cam step and engaging the abutment means with the second cam step to lean and reduce the mixture flow to the engine to improve emissions while minimizing engine stalling, the control means comprising a vacuum servo, a vacuum line connecting the engine manifold vacuum to the servo, linkage means connected to and actuated by the servo, and a longitudinally extending cam slide rail secured to and movable with the linkage means and positioned adjacent to the cam member follower surface and fast idle cam follower surface, the rail having first and second cam portions projecting laterally from the rail in opposite directions for separate engagement with the cam member cam follower surface and fast idle cam cam follower surface, respectively the first and econd cam portions also being spaced from each other along the lontitudinal extent of the rail to effect the progressive engagement of the slide rail cam portions with the cam member and fast idle cam follower surfaces to effect the above said progressive opening of the choke valve and rotation of the fast idle cam upon supply of vacuum to the servo.

Claim 10

A carburetor having an air/fuel induction passage open at one end to air at essentially atmospheric pressure and connected at its opposite end to an engine intake manifold to be subject to the changing vacuum levels therein, the one end having a choke valve rotatably mounted for movement across the passage between a closed air choking position and an open inoperative position, and a throttle valve rotatably mounted posterior of the choke valve for movement across the passage between a normal essentially closed engine idle speed position and beyond towards a wide open throttle position to control the quantity of air/fuel mixture flow through the passage, an abutment means rotatable with the throttle valve, a rotatable fast idle cam having a high cam step projecting radially from the cam axes for engagement at times by the abutment means during movement of the throttle valve in a closing direction to stop the throttle valve in a more open position than the normal idle speed position to increase mixture flow to the manifold, the cam also having a second cam step of lesser radial extent engagable with the abutment means at other times as a function of the rotative position of the cam to stop the throttle valve in a less open position than the high cam step position, the cam being rotatable by gravity towards an inoperative position upon disengagement of the abutment means with the cam step permitting closure of the throttle valve towards the normal idle speed position, a shaft, rotatable lever means secured on the shaft for rotation therewith and connected to the choke valve, the shaft rotatably mounting the fast idle cam and a bellcrank cam member, the cam member having axially spaced projecting portions providing separate one-way interconnections with the lever means and fast idle cam permitting free rotation of the lever means in a choke valve opening direction and the fast idle cam in a direction moving the high cam step towards engagement with the abutment means, both the cam member and cam having separate cam follower surfaces, the cam member one-way interconnection with the fast idle cam comprising a portion extending into the path of rotative movement of the fast idle cam towards the inoperative position permitting stopping of rotation of the cam in this direction, thermostatic spring means to rotate the shaft and lever means, and vacuum mechanical control means operable in response to the engine attaining sustained operation after a cold engine cranking operation while the abutment means is engaged with the fast idle cam high step to automatically and progressively first move the lever means to crack open the choke valve from an initial closed position and subsequently rotate the fast idle cam to a position disengaging the abutment means from the high cam step and engaging the abutment means with the second cam step to lean and reduce the mixture flow to the engine to improve emissions while minimizing engine stalling, the control means comprising a vacuum servo, a vacuum line connecting the engine manifold vacuum to the servo, linkage means connected to and actuated by the servo, and a longitudinally extending cam slide rail secured to and movable with the linkage means and positioned adjacent to the cam member follower surface and fast idle cam follower surface, the rail having first and second cam portions projecting laterally from the rail in opposite directions for separate engagement with the cam member cam follower surface and fast idle cam cam follower surface, respectively the first and econd cam portions also being spaced from each other along the lontitudinal extent of the rail to effect the progressive engagement of the slide rail cam portions with the cam member and fast idle cam follower surfaces to effect the above said progressive opening of the choke valve and rotation of the fast idle cam upon supply of vacuum to the servo.

Claim 11

A carburetor as in claim 8, including means securing the shaft to a thermostatically responsive spring means urging the shaft and lever means in a choke valve closing direction upon decreases in temperature below the engine normal operating temperature level to abut the cam member portions with the lever means and fast idle cam and permit repositioning of the fast idle cam to a high cam step engagement with the abutment means for engine starting purposes.