# US 4,399,775 A · System for controlling cooling water temperature for a water-cooled engine

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- Number: US 4,399,775 A
- Document ID: US4399775A
- Status: Granted
- Kind: A
- Application number: 06/371,759
- Filed: 1982-04-26
- Granted: 1983-08-23
- Earliest claimed: 1981-04-30
- Assignees: Fuji Jukogyo Kabushiki Kaisha
- Inventors: Takayuki Tanaka; Noriaki Kadoi; Akio Yoshimoto
- Web page: https://patentgrep.com/patent/US4399775A

## CPC

- F01P 7/167: {by adjusting the pre-set temperature according to engine parameters, e.g. engine load, engine speed}
- F01P 7/14: the coolant being liquid
- F01P 2025/08: Temperature
- F01P 2025/50: using two or more temperature sensors
- F01P 2025/62: Load
- F01P 2025/64: Number of revolutions
- F01P 2070/06: Using intake pressure as actuating fluid
- F01P: COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES (arrangements in connection with cooling of propulsion units in vehicles B60K11/00; heat-transfer, heat-exchange or heat-storage materials C09K5/00; {cooling of gas-turbine engines F02C7/12}; heat exchange in general, radiators F28)

## Abstract

A system for controlling cooling water temperature for a water-cooled engine has a radiator, a cooling water passage communicating a water jacket in the engine with the radiator, and a thermostat provided in the cooling water passage. The system is provided with a bypass for bypassing the thermostat, a bypass valve provided in the bypass for closing the bypass, and a solenoid operated valve for actuating the bypass valve. Switch circuits are connected parallel to a solenoid of the solenoid operated valve means. The switch circuits comprise a thermo-switch responsive to low cooling water temperature to effect the operation of the solenoid operated valve for closing the bypass valve of the bypass, a vacuum switch responsive to a vacuum in the intake passage at heavy load operation of the engine to effect the operation of said solenoid operated valve for opening the bypass valve, whereby the cooling water temperature is controlled according to the engine operation.

## Claims

### Claim 1

A system for controlling cooling water temperature for a water-cooled engine having an intake passage, a radiator, a cooling water passage communicating a water jacket in said engine with said radiator, and a thermostat provided in said cooling water passage, said thermostat being so arranged as to open said passage when the cooling water temperature exceeds a predetermined value, said system comprising
a bypass for bypassing said thermostat;
a bypass valve provided in said bypass for closing the bypass;
solenoid operated valve means for actuating said bypass valve; and
a thermo switch and a vacuum switch connected parallel to a solenoid of said solenoid operated valve means;
said thermo switch being responsive to a low cooling water temperature to effect the operation of said solenoid operated valve for closing said bypass valve of said bypass,
said vacuum switch having a vacuum chamber which is communicated with said intake passage via a restriction,
said vacuum switch being responsive to a vacuum at heavy load operation to effect the operation of said solenoid operated valve for opening said bypass valve.

### Claim 2 (depends on 1)

The system for controlling cooling water temperature for a water-cooled engine according to claim 1 wherein said bypass valve provided in said bypass is a vacuum operated valve.