Speed control actuator

In speed control apparatus including means for generating a speed correction signal related at least to the sign of the value of the difference between an actual speed and a predetermined desired speed, an actuator comprising:

• a reversible electric motor connectable to receive said speed correction signal;
• first means in permanent driving connection with said motor and including a first clutch surface;
• second means selectively drivingly engageable and disengageable relative to said first means and including a second clutch surface, a pulley in permanent driving connection with said second clutch surface and having a circumferentially extending peripheral groove, a cable having an end fixed with respect to said pulley, a cable portion adjacent said end extending around said pulley and engaged in said groove, and means connecting the opposite end of the cable to a displaceable power control member of a prime mover to be controlled, said cable forming a double-acting connection between and normally permanently interconnecting said pulley and power control member whereby, at any instant, the rotated position of said second clutch surface and pulley will correspond to the position of said power control member;
• and
• means operative on engagement of the speed control to connect the speed control signal to drive the electric motor and to change said first and second clutch surfaces from a mutually declutched condition in which said second means is free to move with and is driven by said power control member, to a mutually clutched condition at the rotated position of said second clutch surface and pulley corresponding to the instantaneous position of said power control member in which said second means, and therefore said power control member, are driven by said electric motor via the clutched first and second clutch surfaces to the position corresponding to said predetermined desired speed.

In a land vehicle including:

• an engine operable to drive the vehicle, the engine having an adjustable throttle for controlling the speed of the engine and therefore the speed of the vehicle;
• an accelerator pedal permanently connected to said throttle, a speed control system including speed control circuitry operable to generate a speed correction signal which varies in dependence upon the difference between a predetermined required forward speed of the vehicle and the actual forward speed of the vehicle, means for selectively engaging and disengaging said speed control system to control the vehicle speed, an actuator controlled by said speed correction signal and connected to said throttle;
• and means operative on engaging the speed control system to connect the speed correction signal to control said actuator, whereby the throttle is selectively displaceable by the accelerator pedal and by said speed control system when the latter is engaged;
• the improvement wherein the actuator includes:
• (a) a reversible electric motor, at least the direction of rotation of which is controlled by said speed correction signal;
• (b) a clutch including first and second rotatable members and clutch actuating means operable to cause said first and second clutch members to become drivingly engaged when said speed control system is engaged, and to become drivingly disengaged when said speed control system is disengaged;
• (c) reduction gearing permanently drivingly interconnecting said electric motor and said first clutch member, whereby rotation of the electric motor produces, via the reduction gearing, relatively fine angular adjustment of said first clutch member;
• and
• (d) a bidirectionally-acting connection normally permanently interconnecting said throttle and second clutch member, whereby, when said speed control system is disengaged, displacement of the throttle in a throttle-opening direction correspondingly rotates said second clutch member in one direction independently of said first clutch member, and displacement of the throttle in a throttle-closing direction correspondingly rotates said second clutch member in the reverse direction independently of said first clutch member;
• whereby, at any instant, the rotated position of said second clutch member will correspond to the position of said throttle, and immediately upon said speed control system being engaged said first and second clutch members are drivingly interengaged at the rotated position of said second clutch member corresponding to the instantaneous position of said throttle, and the electric motor will be controlled by the speed correction signal to rotate the two clutch members together to displace the throttle to the position for driving the vehicle at the predetermined required forward speed.