Servo apparatus for an automatic speed control of vehicles

Claim 1

Servo apparatus for automatic control of an engine throttle in accordance with an error signal, comprising: an electric motor, adapted to have a direct linkage on its shaft which is connectable to a vehicle engine throttle to open the throttle against a biasing force by shaft rotation in one direction, and to release the throttle by rotation in the other direction; a sampling circuit for sampling stable motor back emf values; a pulsed waveform signal generator having its output connected to drive the motor, and an input for a control signal in accordance with which the pulsed waveform signal is variable to vary the motor torque in the direction of rotation of throttle opening; a control unit having its output connected to the generator control signal input, and having an error signal input, and a further input connected to receive values from the sampling circuit, the unit being adapted to vary the pulsed waveform signal to rotate the shaft in accordance with the error signal and open the throttle in a controlled manner, to use the sampling circuit input in addition to the error signal to vary the pulsed waveform signal to allow the shaft to rotate and release the throttle under the biasing force, and, to maintain the motor in a stalled condition.

Claim 10

A method of automatically controlling an engine throttle in accordance with an error signal, comprising: connecting an electric motor directly to the throttle to open the throttle against a biasing force by motor shaft rotation in a first direction, and to release the throttle under the biasing force by shaft rotation in the second direction; producing a pulsed waveform signal to drive the electric motor to open the throttle; varying the pulsed waveform signal to vary the torque of the motor in the first rotational direction; sampling the motor back emf when it is stable; and, controlling the variation of the pulsed waveform in accordance with the error signal to cause controlled opening of the throttle, and additionally in accordance with the sampled emf, to cause controlled release of the throttle, and to cause the throttle to be held in a set position with the motor stalled, in order to control the engine speed.

Claim 11

A method of automatically controlling an engine throttle in accordance with an error signal, comprising: connecting an electric motor directly to the throttle to open the throttle against a biasing force by motor shaft rotation in a first direction, and to release the throttle under the biasing force by shaft rotation in the second direction; producing a pulsed waveform signal to drive the electric motor to open the throttle; varying the pulsed waveform signal to vary the torque of the motor in the first rotational direction; sampling the motor back emf when it is stable; and, controlling the variation of the pulsed waveform in accordance with the error signal to cause controlled opening of the throttle, and additionally in accordance with the sampled emf, to cause controlled release of the throttle, and to cause the throttle to be held in a set position with the motor stalled, in order to control the engine speed.

Claim 15

A method as claimed in any one of claims 10, 11 or 12 in which sampled values are accumulated and used only when they are negative relative to the pulsed waveform signal.