Low overshoot engine speed governor

• US 4,217,867 A
• Filed: 05/29/1979
• Issued: 08/19/1980
• Est. Priority Date: 05/29/1979
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Madsen, Wayne A., Ely, Jeffrey A., Kibler, Roland G.
• Primary Examiner(s): Cox, Ronald B.
• Application Number:
  US06/043,314
• Time in Patent Office: 448 Days
• Field of Search: 123/102, 180/105 C, 317/5
• US Class Current: 123/352
• CPC Class Codes: F02D 11/10 of the electric type
• CPC Class Codes: F02D 2200/1012 Engine speed gradient
• CPC Class Codes: F02D 31/001 Electric control of rotation speed
• CPC Class Codes: F02D 31/006 for maximum speed control

Abstract

A governor circuit for limiting the maximum speed of an internal combustion engine is effective to minimize overshoot at all ranges of engine acceleration. The system includes a circuit responsive to the engine speed which provides control signals to a solenoid valve which, in turn, controls a vacuum actuator which can override a manual throttle control to move the throttle toward closed position when a governed engine speed is approached. A control circuit provides a signal having a lead component and an integrated signal which comprises a stabilizing component and an integrated speed component. The integrated signal is provided by an integrator having a low sensitivity and high gain at low engine accelerations and a high sensitivity and low gain at engine accelerations above a predetermined switch point. The resulting control signal controls a duty cycle oscillator which actuates the solenoid valve.

Claims

1. In a system for limiting engine speed to near a governed value having means for limiting engine speed, a control circuit for actuating the limiting means comprising,

speed means for producing an electrical speed signal proportional to engine speed,

a modifying circuit responsive to the speed signal for producing a control signal for energizing the limiting means as a function of engine speed, the modifying circuit including a lead circuit providing a lead term in accordance with engine acceleration, and a variable sensitivity integrator in parallel with the lead circuit, each providing components of the control signal,

the variable sensitivity integrator connected to the speed means and selectively placed in a low sensitivity mode effective during low engine acceleration and in a high sensitivity mode effective during intermediate and high engine acceleration, the integrator including sensitivity adjustment means, and rate means connected to the speed means and responsive to the engine acceleration and connected to the sensitivity adjustment means of the integrator for effecting the respective high and low sensitivity integrator modes, the integrator input impedance including a differentiator responsive to the speed signal for producing a stabilizing component in the output signal,

whereby the control circuit is conditioned to actuate the limiting means for limiting engine speed to a governed value for all values of engine acceleration.

2. In a system for limiting engine speed to near a governed value having means for limiting engine speed, a control circuit for actuating the limiting means comprising,

speed means for producing an electrical speed signal proportional to engine speed,

a modifying circuit responsive to the speed signal for producing a control signal for energizing the limiting means as a function of engine speed, the modifying circuit including a lead circuit providing a lead term in accordance with engine acceleration, and a variable sensitivity and gain integrator in parallel with the lead circuit, each providing components of the control signal,

the variable sensitivity and gain integrator connected to the speed means and selectively placed in a low sensitivity/high gain mode effective during low engine acceleration and in a high sensitivity/low gain mode effective during intermediate and high engine acceleration, and a rate switch connected to the speed means and responsive to the engine acceleration for assuming a first switch state above a set acceleration switch point and a second switch state below the set switch point, and means connected to the rate switch and responsive to the state thereof for adjusting the integrator feedback impedance and input bias current so that when the rate switch is in its first state the integrator has a low gain and high sensitivity to small input signals and when in its second state the integrator has a high gain and a lower sensitivity to small input signals, the integrator input impedance including a differentiator responsive to the speed signal for producing a stabilizing component in the output signal when the integrator is in high gain mode and a further lead term when in low gain mode;

whereby the control circuit is conditioned to actuate the limiting means for limiting engine speed to a governed value for all values of engine acceleration.

3. In a system for limiting engine speed to near a governed value having means for limiting engine speed, a control circuit for actuating the limiting means comprising,

speed means for producing an electrical speed signal proportional to engine speed,

a modifying circuit responsive to the speed signal for producing a control signal for energizing the limiting means as a function of engine speed, the modifying circuit including a lead circuit providing a lead term in accordance with engine acceleration, and a variable sensitivity integrator in parallel with the lead circuit, each providing components of the control signal,

the variable sensitivity integrator connected to the speed means and selectively placed in a low sensitivity mode effective during low engine acceleration and in a high sensitivity mode effective during intermediate and high engine acceleration, the integrator comprising an operational amplifier having a first input terminal, an integrator input impedance connected to the first input terminal including a differentiator responsive to the speed signal for producing a stabilizing component in the output signal, a feedback path connected between the amplifier output and a second input terminal to establish integrator action, input bias current means connected to the second input terminal to determine a nominal sensitivity level, and sensitivity control means for selectively supplying additional bias current to the input to decrease the sensitivity including a rate switch connected to the speed means and responsive to the engine acceleration and coupled to the said second input terminal to selectively apply the additional bias current thereto,

whereby the control circuit is conditioned to actuate the limiting means for limiting engine speed to a governed value for all values of engine acceleration.

4. In a system for limiting engine speed to near a governed value having means for limiting engine speed, a control circuit for actuating the limiting means comprising,

speed means for producing an electrical speed signal proportional to engine speed,

a modifying circuit responsive to the speed signal for producing a control signal for energizing the limiting means as a function of engine speed, the modifying circuit including a lead circuit providing a lead term in accordance with engine acceleration, and a variable sensitivity and gain integrator in parallel with the lead circuit, each providing components of the control signal,

the variable sensitivity and gain integrator connected to the speed means and selectively placed in a low sensitivity/high gain mode effective during low engine acceleration and in a high sensitivity/low gain mode effective during intermediate and high engine acceleration, the integrator comprising an operational amplifier having a capacitive feedback path, a first resistive feedback path and a second feedback path including a pair of resistors in series connected at a junction point, the feedback paths connected in parallel between the amplifier output and input whereby the feedback path establishes the gain of the integrator, a sensitivity circuit including input bias current means connected to the amplifier input, control means for increasing the gain and decreasing the sensitivity by applying a high voltage at the said junction point to augment the input bias current and to disable the second resistive path, the control means including a rate switch connected to the speed means and responsive to the engine acceleration and connected to the said junction point to selectively apply the voltage thereto for effecting the respective sensitivity and gain changes, the integrator input impedance including a differentiator responsive to the speed signal for producing a stabilizing component in the output signal when the integrator is in high gain mode and a further lead term when in low gain mode;

whereby the control circuit is conditioned to actuate the limiting means for limiting engine speed to a governed value for all values of engine acceleration.