# US 4,397,368 A · Driving circuits of solenoid actuated devices

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- Number: US 4,397,368 A
- Document ID: US4397368A
- Status: Granted
- Kind: A
- Application number: 06/013,718
- Filed: 1979-02-21
- Granted: 1983-08-09
- Earliest claimed: 1978-03-06
- Assignees: Jidosha Kiki Co., Ltd.
- Inventors: Sadao Takeshima
- Web page: https://patentgrep.com/patent/US4397368A

## CPC

- B62D 5/062: {Details, component parts}
- B62D 5/065: characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist
- B62D 6/02: responsive only to vehicle speed
- H01H 47/325: {by switching regulator}
- H03K 3/023: by the use of differential amplifiers or comparators, with internal or external positive feedback
- B62D: MOTOR VEHICLES; TRAILERS (steering, or guiding on a desired track, of agricultural machines or implements A01B69/00; wheels, castors, axles, increasing wheel adhesion B60B; vehicle tyres, tyre inflation or tyre changing B60C; connections between vehicles of a train or the like B60D; vehicles for use on rail and road, amphibious or convertible vehicles B60F; suspension arrangements B60G; heating, cooling, ventilating or other air treating devices B60H; windows, windscreens, non-fixed roofs, doors or similar devices, protective coverings for vehicles not in use B60J; propulsion plant arrangements, auxiliary drives, transmissions, controls, instrumentation or dashboards B60K; electric equipment or propulsion of electrically-propelled vehicles B60L; power supply for electrically-propelled vehicles B60M; passenger accommodation not otherwise provided for B60N; adaptations for load transportation or to carry special loads or objects B60P; arrangement of signalling or lighting devices, the mounting or supporting thereof or circuits therefor, for vehicles in general B60Q; vehicles, vehicle fittings or vehicle parts not otherwise provided for B60R; servicing, cleaning, repairing, supporting, lifting, or manoeuvring, not otherwise provided for, B60S; brake arrangements, brake control systems or parts thereof B60T; air-cushion vehicles B60V; motor-cycles, accessories therefor B62J, B62K; testing of vehicles G01M)
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

In a solenoid actuated device for controlling the oil supplied to a power steering unit of a motor car, a driving circuit is provided to pass current through the solenoid. The driving circuit comprises a comparator supplied with an analogue control signal proportional to the running speed of the motor car, a power amplifier including an output transistor which supplies exciting current to the solenoid coil in response to the output of the comparator. A positive feedback resistor is connected between the output of the comparator and the input thereof to which the analogue signal is applied, and a negative feedback resistor is connected between the output of the power amplifier another input of the comparator thereby ON-OFF controlling the output transistor to pass pulse current through the solenoid coil.

## Claims

### Claim 1

In a driving circuit of a solenoid actuated device of the type wherein a plunger is actuated by a solenoid coil, the driving circuit comprising a comparator having a first input supplied with an analog control signal representing an operating condition of a member to be controlled by the plunger, a second input, and an output; and a power amplifier circuit including an output amplifier in the form of an output transistor for supplying exciting current to the solenoid coil in response to the output of the comparator, the improvement comprising means coupled to said coil for detecting a voltage corresponding to said exciting current, positive feedback means, connected between said first input of said comparator and the output of one of said comparator and said output amplifier, and negative feedback means connected between said second comparator input and a junction between said detecting means and said coil, in order to provide ON-OFF control of said output transistor such that said exciting current comprises a current proportional to said analog control signal.

### Claim 2 (depends on 1)

The driving circuit according to claim 1 wherein said solenoid actuated device controls operating fluid supplied to a power steering unit of a motor car and said analog control signal is proportional to the running speed of said motor car.

### Claim 3 (depends on 1)

The driving circuit according to claim 1 wherein said positive feedback means is connected between the output terminal of said power amplifier circuit and said first input terminal of said comparator.

### Claim 4 (depends on 1)

The driving circuit according to claim 1 wherein said positive feedback means is connected to said output terminal of said comparator and said input terminal thereof.

### Claim 5 (depends on 1)

The driving circuit according to claim 1 wherein said positive feedback means comprises two serially connected resistors connected between the output of said amplifier circuit and said first input terminal of said comparator, and wherein a constant voltage element is connected between the junction between said serially connected resistors and a point of reference potential.