Cooling system for working fluid used in automatic transmission of automotive vehicle

• US 20020128107A1
• Filed: 01/03/2002
• Published: 09/12/2002
• Est. Priority Date: 03/09/2001
• Status: Active Grant

• Current Assignee: Jatco Limited (Nissan Motor Co., Ltd.)
• Original Assignee: Jatco Transtechnology Limited
• Inventors: Wakayama, Hideshi
• Granted Patent: US 6,740,000 B2
• Time in Patent Office: Days
• US Class Current: 475/161
• CPC Class Codes: F16H 57/0412 Cooling or heating; Control of temperature
• CPC Class Codes: F16H 57/0413 Controlled cooling or heating of lubricant; Temperature control therefor
• CPC Class Codes: F16H 57/0434 relating to lubrication supply, e.g. pumps arrangement of pumps F16H57/0441; Pressure control grooves with pumping effect for supplying lubricant F16H57/0428; generation and variation of line pressure for transmission control F16H61/0021
• CPC Class Codes: F16H 59/72 dependent on oil characteristics, e.g. temperature, viscosity
• CPC Class Codes: Y10S 165/916 Oil cooler
• CPC Class Codes: Y10T 137/87362 Including cleaning, treating, or heat transfer feature
• CPC Class Codes: Y10T 74/19991 Lubrication
• CPC Class Codes: Y10T 74/2189 Cooling

Abstract

In a transmission-fluid cooling system of an automatic transmission of an automotive vehicle equipped with a water-cooled oil cooler and an air-cooled oil cooler connected in series to each other, a first bypass valve is provided to permit working fluid to circulate therevia through oil passages in the transmission, bypassing the water-cooled oil cooler and the air-cooled oil cooler, only when a working-fluid temperature is less than or equal to a predetermined temperature and the line pressure is greater than or equal to a predetermined pressure. Also provided is a second bypass valve that opens to permit the working fluid to circulate via the water-cooled oil cooler and the second bypass valve through the oil passages in the transmission, bypassing only the air-cooled oil cooler, only when the working-fluid temperature is less than or equal to a preset temperature value.

Claims

1. A cooling system for working fluid used in an automatic transmission of an automotive vehicle, comprising:

a water-cooled oil cooler and an air-cooled oil cooler connected in series to each other and both disposed in an oil cooler line for cooling the working fluid;

an oil pump located in the automatic transmission and disposed in the oil cooler line for pressurizing and sending the working fluid into the oil cooler line;

a hydraulic control circuit disposed downstream of the oil pump for regulating a line pressure produced by the oil pump;

a lubrication circuit located in the automatic transmission for lubrication of moving transmission parts;

a first bypass valve that opens to permit the working fluid to circulate via the first bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing the water-cooled oil cooler and the air-cooled oil cooler, only when a working-fluid temperature is less than or equal to a predetermined temperature and the line pressure is greater than or equal to a predetermined pressure; and

a second bypass valve that opens to permit the working fluid to circulate via the water-cooled oil cooler and the second bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing only the air-cooled oil cooler, only when the working-fluid temperature is less than or equal to a preset temperature value.

2. The cooling system as claimed in claim 1, wherein the first bypass valve is located within a control valve body included in the hydraulic control circuit.

3. A cooling system for working fluid used in an automatic transmission of an automotive vehicle, comprising:

a water-cooled oil cooler and an air-cooled oil cooler connected in series to each other and both disposed in an oil cooler line for cooling the working fluid;

an oil pump located in the automatic transmission and disposed in the oil cooler line for pressurizing and sending the working fluid into the oil cooler line;

a hydraulic control circuit disposed downstream of the oil pump for regulating a line pressure produced by the oil pump;

a lubrication circuit located in the automatic transmission for lubrication of moving transmission parts;

a first bypass valve that opens in response to a working-fluid temperature as well as the line pressure, to permit the working fluid to circulate via the first bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing the water-cooled oil cooler and the air-cooled oil cooler; and

the first bypass valve being located within a control valve body included in the hydraulic control circuit.

4. The cooling system as claimed in claim 3, wherein:

the first bypass valve opens only when the working-fluid temperature is less than or equal to a predetermined temperature and the line pressure is greater than or equal to a predetermined pressure.

5. A cooling system for working fluid used in an automatic transmission of an automotive vehicle, comprising:

a water-cooled oil cooler and an air-cooled oil cooler connected in series to each other and both disposed in an oil cooler line for cooling the working fluid;

an oil pump located in the automatic transmission and disposed in the oil cooler line for pressurizing and sending the working fluid into the oil cooler line;

a hydraulic control circuit disposed downstream of the oil pump for regulating a line pressure produced by the oil pump;

a lubrication circuit located in the automatic transmission for lubrication of moving transmission parts;

a first bypass valve that opens to permit the working fluid to circulate via the first bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing the water-cooled oil cooler and the air-cooled oil cooler, only when a hydraulic pressure created on the working fluid in a portion of the oil cooler line leading from an outlet of the hydraulic control circuit to an upstream side of the water-cooled oil cooler and the air-cooled oil cooler exceeds a preset pressure level; and

a second bypass valve that opens to permit the working fluid to circulate via the water-cooled oil cooler and the second bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing only the air-cooled oil cooler, only when a working-fluid temperature is less than or equal to a preset temperature value.

6. The cooling system as claimed in claim 5, wherein:

the hydraulic pressure created on the working fluid in the portion of the oil cooler line leading from an outlet of the hydraulic control circuit to the upstream side of the water-cooled oil cooler and the air-cooled oil cooler varies depending on the working-fluid temperature as well as the line pressure.

7. The cooling system as claimed in claim 6, wherein:

the hydraulic pressure created on the working fluid in the portion of the oil cooler line leading from an outlet of the hydraulic control circuit to the upstream side of the water-cooled oil cooler and the air-cooled oil cooler exceeds the preset pressure level only when the working-fluid temperature is less than or equal to a predetermined temperature less than the preset temperature value and the line pressure is greater than or equal to a predetermined pressure greater than the preset pressure level.

8. The cooling system as claimed in claim 5, wherein:

the first bypass valve is located within a control valve body included in the hydraulic control circuit.

9. The cooling system as claimed in claim 5, wherein:

the first bypass valve comprises a pressure relief valve whose set pressure is the preset pressure level; and

the second bypass valve comprises a wax-pellet type bypass valve that is closed by a wax pellet expandable with increasing working-fluid temperature.

10. A cooling system for working fluid used in an automatic transmission of an automotive vehicle, comprising:

a water-cooled oil cooler and an air-cooled oil cooler connected in series to each other and both disposed in an oil cooler line for cooling the working fluid;

an oil pump located in the automatic transmission and disposed in the oil cooler line for pressurizing and sending the working fluid into the oil cooler line;

a hydraulic control circuit disposed downstream of the oil pump for regulating a line pressure produced by the oil pump;

a lubrication circuit located in the automatic transmission for lubrication of moving transmission parts;

a temperature sensor that detects a working-fluid temperature;

a first bypass valve that permits the working fluid to circulate via the first bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing the water-cooled oil cooler and the air-cooled oil cooler;

a second bypass valve that permits the working fluid to circulate via the water-cooled oil cooler and the second bypass valve through the oil pump, the hydraulic control circuit and the lubrication circuit, bypassing only the air-cooled oil cooler; and

a control unit configured to be connected electronically to the temperature sensor, and the first and second bypass valves, for automatically controlling opening and closing operations of each of the first and second bypass valves depending on the line pressure as well as the working-fluid temperature and for controlling the line pressure depending on a sensor signal from the temperature sensor;

the control unit comprising;

(a) a first bypass valve control section keeping the first bypass valve opened in a first control mode area that the working-fluid temperature is low and the line pressure is high; and

(b) a second bypass valve control section keeping the second bypass valve closed in a second control mode area that the working-fluid temperature is high.

11. The cooling system as claimed in claim 10, wherein:

the first and second bypass valve control sections keep the first bypass valve closed and keep the second bypass valve opened in a third control mode area defined between the first and second control mode areas.

12. The cooling system as claimed in claim 11, wherein the first bypass valve is located within a control valve body included in the hydraulic control circuit.