Pulse-width-modulation control of parallel three-way valves to supply single-acting quick-response actuator
AssigneeHitachi, Ltd.
InventorsMotoo Uno, Ikuo Takeuchi, Kazuo Honma, Akihiko Sakai
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Abstract
Parallel, pulse-width-modulation controlled three-way valves each both supply and exhaust a pressure chamber of a fluid actuator. The phase difference of the oscillator carrier waves of the pulse width modulation input circuit effectively increases the frequency of a net actuator carrier wave so as to quicken the response of the actuator.
Claims29
A control apparatus for an actuator responsive to fluid pressure therein including a plurality of actuator drivers connected to said actuator and controlled in accordance with an error voltage signal indicating the difference between a pressure reference signal and a pressure feedback signal of said actuator and wherein operation of said actuator is controlled by fluid pressure supplied thereto by said plurality of actuator drivers, comprising:
- pressure reference signal generator means for providing a reference voltage signal corresponding to a pressure refrence;
- pressure sensor means for providing a pressure signal based on the pressure in said actuator;
- error voltage producing means, coupled to said pressure reference signal generator means and said pressure sensor means, for producing an error voltage signal as a function of the difference between the reference voltage signal from said pressure reference signal generator means and the pressure signal from said pressure sensor means;
- oscillator means for generating a plurality of phase-shifted carrier wave signals corresponding in number to the number of said actuator dirvers;
- and
- pulse width modulation means, coupled to receive said plurality of carrier wave signals from said oscillator means and said error voltage signal from said error voltage producing means, for producing a plurality of trains of pulse signals corresponding to the number of said drivers, being respectively out-of-phase with each other with a relative phase difference dependent upon the relative phase difference of said carrier wave signals and each having a duty ratio proportional to said error voltage signal for respectively controlling each of said plurality of actuator drivers, whereby as a result of said plurality of actuator drivers being controllably actuated by said plurality of phase-shifted trains of pulse signals, there results in enhanced control of said actuator by effectively increasing the frequency of the carrier wave for said actuator.
A control apparatus for a single action actuator having a fluid chamber, including a plurality of control valves for operating the actuator and width are controlled in accordance with an error voltage signal producing means between a pressure reference signal and a pressure feedback signal corresponding to the pressure in said fluid chamber of the actuator and wherein operation of the actuator is controlled by fluid pressure in response to said plurality of control valves, comprising:
- an oscillator for generating a plurality of phase-shifted carrier wave signals corresponding to the number of said control valves;
- and
- a plurality of pulse width modulation circuits, responsive to said carrier wave signals and said error voltage signal, for outputting a plurality of phase-shifted trains of pulse signals having a relative phase difference dependent upon the relative phase difference of said plurality of carrier wave signals and being equal in number to the number of said control valves and each having a duty ratio proportional to said error voltage signal for respectively controlling each of said plurality of control valves, whereby as a result of said plurality of control valves being controllably actuated by said plurality of phase-shifted trains of pulse signals, there results in enhanced control of said actuator by effectively increasing the frequency of the carrier wave for said actuator.
A control apparatus for an actuator responsive to fluid pressure therein including a plurality of three-way valves connected to said actuator and controlled in accordance with an error voltage signal indicating the difference between a pressure reference signal and a pressure feedback signal of said actuator and wherein operation of said actuator is controlled by fluid pressure supplied thereto by said plurality of three-way valves, comprising:
- pressure reference signal generator means for providing a reference voltage signal corresponding to a pressure reference;
- pressure sensor means for providing a pressure signal based on the pressure in said actuator;
- error voltage producing means, coupled to said pressure reference signal generator means and said pressure sensor means, for producing an error voltage signal as a function of the difference between the reference voltage signal from said pressure reference signal generator means and the pressure signal from said pressure sensor means;
- oscillator means for generating a plurality of phase-shifted carrier wave signals corresponding in number to the number of said three-way control valves;
- and
- pulse width modulation means, coupled to receive said plurality of carrier wave signals from said oscillator means and said error voltage signal from said error voltage producing means, for producing a plurality of trains of pulse signals corresponding to the number of said three-way control valves, being respectively out-of-phase with each other and each having a duty ratio proportional to said error voltage signal for respectively controlling each of said plurality of three-way control valves, whereby as a result of said plurality of three-way control valves being controllably actuated by said plurality of phase-shifted trains of pulse signals, there results in enhanced control of said actuator by effectively increasing the frequency of the carrier wave for said actuator.
A control apparatus for a single action actuator having a fluid chamber, including a plurality of three-way control valves for operating the actuator and which are controlled i n accordance with an error voltage signal producing means between a pressure reference signal and a pressure feedback signal corresponding to the pressure in said fluid chamber of the actuator and wherein operation of the actuator is controlled by fluid pressure in response to said plurality of three-way control valves, comprising:
- an oscillator for generating a plurality of phase-shifted carrier wave signals corresponding to the number of said control valves;
- and
- a plurality of pulse width modulation circuits, responsive to said carrier wave signals and said error voltage signal, for outputting a plurality of phase-shifted trains of pulse signals equal in number to the number of said three-way control valves and each having a duty ratio proportional to said error voltage signal for respectively controlling each of said plurality of three-way control valves, whereby as a result of said plurality of three-way valves being controllably actuated by said plurality of phase-shifted trains of pulse signals, there results in enhanced control of said actuator by effectively increasing the frequency of the carrier wave for said actuator.
Dependencies are inferred from the claim text.