초록

A hydraulic control system of an eight-speed automatic transmission for a vehicle. Four clutches and two brakes can by independently controlled by six proportional control solenoid valves by employing pressure control valves and pressure switching valves.

대표청구항 ▼

What is claimed is: 1. A hydraulic control system of an eight-speed automatic transmission for a vehicle for controlling a first clutch operated at first, second, third, and fourth forward speeds and an L range, a second clutch operated at fourth, fifth, sixth, seventh, and eighth forward speeds, a

What is claimed is: 1. A hydraulic control system of an eight-speed automatic transmission for a vehicle for controlling a first clutch operated at first, second, third, and fourth forward speeds and an L range, a second clutch operated at fourth, fifth, sixth, seventh, and eighth forward speeds, a third clutch operated at the third and fifth forward speeds and a reverse speed, a fourth clutch operated at the sixth forward speed, a first brake operated at the second and seventh forward speeds, and a second brake operated at the eighth forward speed and the L range, the hydraulic control system comprising: a first clutch control portion that provides a first supply of a D range pressure to the first clutch, the first supply of the D range pressure being controlled by a first pressure control valve and a first pressure switching valve by a control of a first proportional control valve; a second clutch control portion that provides a second supply of the D range pressure to the second clutch via a first fail-safe valve, the second supply of the D range pressure being controlled by a second pressure control valve and a second pressure switching valve by a control of a second proportional control valve; a third clutch control portion that provides a first supply of a line pressure to the third clutch, the first supply of the line pressure being controlled by a third pressure control valve and a third pressure switching valve by a control of a third proportional control valve, a second supply of the line pressure to the third pressure control valve being controlled by a fourth pressure switching valve by a control of a fourth proportional control valve; a first brake control portion that provides a third supply of the D range pressure to the first brake, the third supply of the D range pressure being controlled by the fourth pressure control valve and a fourth pressure switching valve by a control of the fourth proportional control valve, a fourth supply of the D range pressure to the fourth pressure control valve being controlled by the third pressure switching valve by a control of the third proportional control valve; a second brake control portion that provides a third supply of the line pressure or a supply of an R range pressure to the second brake via a second fail-safe valve, the third supply of the line pressure being controlled by a fifth pressure control valve and a fifth pressure switching valve by a fifth proportional control valve, a fourth supply of the line pressure to the fifth pressure control valve being controlled by a sixth pressure switching valve by a control of a sixth proportional control valve, and the R range pressure being directly supplied from a manual valve to the second fail-safe valve; and a fourth clutch control portion that provides a fifth supply of the D range pressure to the fourth clutch via a third fail-safe valve, the fifth supply of the D range pressure being controlled by a sixth pressure control valve and the sixth pressure switching valve by a control of the sixth proportional control valve, and a sixth supply of the D range pressure to the sixth pressure control valve being controlled by the fifth pressure switching valve by a control of the fifth proportional control valve. 2. The hydraulic control system of claim 1, wherein: each of the first, second, third, fourth, fifth, and sixth proportional control valves independently supplies a reduced pressure of a first reducing valve to the first, second, third, fourth, fifth, and sixth pressure control valves and the first, second, third, fourth, fifth, and sixth pressure switching valves as control pressures; and the first, second, third, fourth, fifth, and sixth pressure switching valves commonly receive a control pressure from a second reducing valve. 3. The hydraulic control system of claim 1, wherein the line pressure, an operating pressure of the first clutch, an operating pressure of the third clutch or the first brake, and an operating pressure of the second brake or the fourth clutch are supplied as control pressures to the first fail-safe valve through four routes. 4. The hydraulic control system of claim 1, wherein an N/D range pressure and the operating pressure of the third clutch and the first brake are supplied as control pressures to the second fail-safe valve through three routes. 5. The hydraulic control system of claim 1, wherein the line pressure and the operating pressure of the third clutch and the first brake are supplied as control pressures to the third fail-safe valve. 6. The hydraulic control system of claim 3, further comprising a first shuttle valve between the third clutch and the first brake such that a selective one of the operating pressures of the third clutch and the first brake may be supplied to the first, second, and third fail-safe valves. 7. The hydraulic control system of claim 3, further comprising a second shuttle valve between the second brake and the fourth clutch such that a selective one of the operating pressures of the second brake and the fourth clutch may be supplied to the first fail-safe valve. 8. The hydraulic control system of claim 1, wherein the first pressure control valve is integrally formed with the first proportional control valve and comprises a valve body and a valve spool, wherein the valve body of the first pressure control valve comprises a first port that receives a control pressure from the first proportional control valve, a second port that receives the D range pressure a third port that supplies the hydraulic pressure of the second port to the first clutch, a fourth port that exhausts the hydraulic pressure supplied to the first clutch, and a fifth port that receives the partial pressure of the operating pressure supplied to the first clutch through the first pressure switching valve. 9. The hydraulic control system of claim 1, wherein the first pressure switching valve comprises a valve body and a valve spool, wherein the valve body of the first pressure switching valve comprises a first port that receives the reduced pressure of the second reducing valve, a second port that receives the control pressure from the first proportional control valve at an opposite side of the first port a third port that receives the partial pressure of the operating pressure supplied to the first clutch through the first pressure control valve, a fourth port that is connected with the fifth port of the first pressure control valve, and a fifth port that selectively communicates with the fourth port. 10. The hydraulic control system of claim 1, wherein the second pressure control valve is integrally formed with the second proportional control valve and comprises a valve body and a valve spool, wherein the valve body of the second pressure control valve comprises a first port that receives a control pressure from the second proportional control valve, a second port that receives the D range pressure, a third port that supplies the hydraulic pressure of the second port to the second pressure switching valve and the first fail-safe valve, a fourth port that exhausts the hydraulic pressure supplied to the third port, and a fifth port that receives a partial pressure of the hydraulic pressure supplied to the second pressure switching valve. 11. The hydraulic control system of claim 2, wherein the second pressure switching valve comprises a valve body and a valve spool, wherein the valve body comprises a first port that receives the reduced pressure of the second reducing valve, a second port that receives the control pressure from the second proportional control valve at an opposite side of the first port, a third port that receives a partial pressure of the hydraulic pressure supplied to the first fail-safe valve, a fourth port that connects the third port with the fifth port of the second pressure control valve, a fifth port that is connected with the third proportional control valve, a sixth port that is connected with the fourth proportional control valve, a seventh port that supplies the hydraulic pressure of the fifth port to the third pressure control valve as a control pressure, a eighth port that exhausts the hydraulic pressure supplied to the seventh port, a ninth port that supplies the hydraulic pressure of the sixth port to the fourth pressure control valve, and a tenth port that exhausts the hydraulic pressure supplied to the ninth port. 12. The hydraulic control system of claim 1, wherein the first fail-safe valve comprises a valve body and a valve spool, wherein the valve body of the first fail-safe valve comprises a first port that receives a partial pressure of the operating pressure of the first clutch as a control pressure, a second port that selectively receives the operating pressure of the fourth clutch or the second brake as a control pressure, a third port that selectively receives the operating pressure of the third clutch or the first brake as a control pressure, a fourth port that receives the hydraulic pressure from the second pressure control valve, a fifth port that supplies the hydraulic pressure supplied through the fourth port to the second clutch, a sixth port that receives the line pressure as a control pressure, and a seventh port that exhausts the hydraulic pressure supplied to the fifth port. 13. The hydraulic control system of claim 1, wherein the third pressure control valve is integrally formed with the third proportional control valve and comprises a valve body and a valve spool, wherein the valve body of the third pressure control valve comprises a first port that receives a control pressure from the third proportional control valve, a second port that is connected with the second pressure switch valve so as to form an exhaust line, a third port that receives the hydraulic pressure from the fourth pressure switching valve, a fourth port that supplies the hydraulic pressure of the third port to the third clutch, a fifth port that exhausts the hydraulic pressure supplied to the fourth port, and a sixth port that receives a control pressure from the third pressure switching valve. 14. The hydraulic control system of claim 2, wherein the third pressure switching valve comprises a valve body and a valve spool, wherein the valve body of the third pressure switching valve comprises a first port that receives the reduced pressure of the second reducing valve, a second port that receives the control pressure from the third proportional control valve at an opposite side of the first port, a third port that receives the partial pressure of the hydraulic pressure supplied to the third clutch through the third pressure control valve, a fourth port that connects the third port with the sixth port of the third pressure control valve, a fifth port that selectively communicates with the fourth port so as to exhaust the hydraulic pressure of the fourth port, a sixth port that receives the D range pressure, a seventh port that selectively supplies the hydraulic pressure of the sixth port to the fourth pressure control valve, and an eighth port that selectively exhausts the hydraulic pressure of the seventh port. 15. The hydraulic control system of claim 1, wherein the fourth pressure control valve is integrally formed with the fourth proportional control valve and comprises a valve body and a valve spool, wherein the valve body of the fourth pressure control valve comprises a first port that receives a control pressure from the fourth proportional control valve, a second port that is connected with the second pressure switch valve so as to form an exhaust line, a third port that receives the hydraulic pressure from the third pressure switching valve, a fourth port that supplies the hydraulic pressure of the third port to the first brake, a fifth port that exhausts the hydraulic pressure supplied to the fourth port, and a sixth port that receives a control pressure from the fourth pressure switching valve. 16. The hydraulic control system of claim 1, wherein the fourth pressure switching valve comprises a valve body and a valve spool, wherein the valve body of the fourth pressure switching valve comprises a first port that receives the reduced pressure of the second reducing valve, a second port that receives the control pressure from the fourth proportional control valve at an opposite side of the first port, a third port that receives the partial pressure of the hydraulic pressure supplied to the first brake through the fourth pressure control valve, a fourth port that connects the third port with the sixth port of the fourth pressure control valve, a fifth port that receives the line pressure, a sixth port that supplies the hydraulic pressure received through the fifth port to the third pressure control valve, a seventh port that selectively exhausts the hydraulic pressure of the fourth port, and an eighth port that selectively exhausts the hydraulic pressure of the sixth port. 17. The hydraulic control system of claim 1, wherein the fifth pressure control valve is integrally formed with the fifth proportional control valve and comprises a valve body and a valve spool, wherein the valve body of the fifth pressure control valve comprises a first port that receives a control pressure from the fifth proportional control valve, a second port that receives the line pressure from the sixth pressure switching valve, a third port that supplies the hydraulic pressure of the second port to the second fail-safe valve, a fourth port that exhausts the hydraulic pressure supplied to the third port, and a fifth port that receives a partial pressure of the operating pressure supplied to the fifth pressure switching valve. 18. The hydraulic control system of claim 1, wherein the fifth pressure switching valve comprises a valve body and a valve spool, wherein the valve body of the fifth pressure switching valve comprises a first port that receives the reduced pressure of the second reducing valve, a second port that receives the control pressure from the fifth proportional control valve at an opposite side of the first port, a third port that receives the partial pressure of the hydraulic pressure supplied to the second fail-safe valve through the fifth pressure control valve, a fourth port that selectively communicates with the third port and is connected with the fifth port of the fifth pressure control valve, a fifth port that receives the D range pressure, a sixth port that supplies the D range pressure supplied to the fifth port to the sixth pressure control valve, and seventh and eighth ports that are exhaust ports. 19. The hydraulic control system of claim 1, wherein the second fail-safe valve comprises a valve body and a valve spool, wherein the valve body of the first pressure switching valve comprises first and second ports that are formed at ends of the valve body and receive the N/D range pressure as control pressures, a third port that receives the hydraulic pressure from the fifth pressure control valve, a fourth port that receives the reverse range pressure, a fifth port that selectively supplies the hydraulic pressure of the third and fourth ports to the second brake, and a sixth port that receives the operating pressure of the third clutch or the first brake as a control pressure. 20. The hydraulic control system of claim 1, wherein the sixth pressure control valve is integrally formed with the sixth proportional control valve and comprises a valve body and a valve spool, wherein the valve body of the sixth pressure control valve comprises a first port that receives a control pressure from the sixth proportional control valve, a second port that receives the D range pressure from the third pressure switching valve, a third port that supplies the hydraulic pressure of the second port to the third fail-safe valve, a fourth port that exhausts the hydraulic pressure supplied to the third port, and a fifth port that receives a control pressure from the sixth pressure switching valve. 21. The hydraulic control system of claim 2, wherein the sixth pressure switching valve comprises a valve body and a valve spool, wherein the valve body of the sixth pressure switching valve comprises a first port that receives the reduced pressure of the second reducing valve, a second port that receives the control pressure from the sixth proportional control valve at an opposite side of the first port, a third port that receives the partial pressure of the hydraulic pressure supplied to the third fail-safe valve through the sixth pressure control valve, a fourth port that connects the third port with the fifth port of the sixth pressure control valve, a fifth port that receives the line pressure, a sixth port that supplies the hydraulic pressure supplied through the fifth port to the fifth pressure control valve, a seventh port that selectively exhausts the hydraulic pressure of the fourth port, and an eighth port that selectively exhausts the hydraulic pressure of the sixth port. 22. The hydraulic control system of claim 1, wherein the third fail-safe valve comprises a valve body and a valve spool, wherein the valve body of the third fail-safe valve comprises first and second ports ends of the valve body that receive the line pressure as a control pressure, a third port that receives the D range pressure from the sixth pressure control valve, a fourth port that supplies the hydraulic pressure supplied through the third port to the fourth clutch, a fifth port that receives the operating pressure of the third clutch or the first brake, and a sixth port that exhausts the hydraulic pressure of the fourth port.