Machine element or mechanism – Gearing – Interchangeably locked
Patent
1995-02-13
1996-07-23
Marmor, Charles A.
Machine element or mechanism
Gearing
Interchangeably locked
477126, 477131, 477155, B60K 4106, F16H 6116
Patent
active
055378870
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a hydraulic control system for an automatic transmission, particularly to a hydraulic control system for 4-speed automatic transmission which can increase power train efficiency by controlling line pressure and can improve the responsiveness of shifting time during gear shifting.
2. Description of Prior Art
A conventional vehicle automatic transmission has a torque converter, a multiple stage transmission gear mechanism connected with the torque converter, and frictional elements actuated by hydraulic pressure for selecting one of the gear ratios of the transmission gear mechanism in accordance with vehicle operating conditions.
The hydraulic control system provides actuating hydraulic pressure pressurized by a fluid pump and required to operate the frictional elements and control valves.
A commonly used automatic transmission of a vehicle has a fluid torque converter which generally includes a pump impeller connected to an engine output shaft to be driven thereby, a turbine runner connected to an input shaft of the transmission, and a stator disposed between the pump impeller and the turbine runner, so that hydraulic fluid is circulated by the engine driven pump impeller through the turbine runner with the aid of the stator which functions to deflect the hydraulic fluid from the turbine runner to a direction where the fluid flow does not disturb the rotation of the pump impeller when the fluid flows from the turbine runner into the pump impeller.
The automatic shift is achieved by the operation of frictional elements such as clutches or kick-down brakes at each gear ratios. Also, a manual valve, the ports of which are converted by selecting a position of a selector lever, is designed to receive fluid from a fluid pump and to supply the fluid to a shift control valve. In case of a 4-speed automatic transmission, the shift control valve has a plurality of ports controlled by an electronic control system.
One example of a hydraulic pressure control system of an automatic transmission for a vehicle is described in FIG. 10, which shows a circuit diagram of a conventional hydraulic control system comprising a torque converter 1 attached to an engine through the engine flexible plate and rotating at engine speed for transmitting power of the engine to an input shaft of the transmission gear mechanism, a damper clutch control valve 2 for controlling the application and release of a damper clutch to increase the power train efficiency inside the torque converter 1, a regulator valve 5 for regulating the output hydraulic pressure of the fluid pump 4 according to the automatic transmission requirements, and a reducing valve 6 for regulating the stable supply of hydraulic pressure to a solenoid valve and the damper clutch control valve 2.
A manual valve 7, which is connected to an outlet of the fluid pump 4 and is provided with the hydraulic pressure, is designed to deliver line pressure to the regulator valve 5 and a shift control valve. The manual valve 7 is changed in position (P,R,N,D,2,L) by a shift lever as shown in FIG. 10.
A shift control valve 8, which is operated in response to two shift control solenoid valves A and B controlled by a transmission control unit (not shown) is designed to transmit the hydraulic pressure selectively through a first-second speed shift valve 9, an end clutch valve 10, a second-third and third-fourth speed shift valve 11, and a rear clutch exhaust valve 12 to a front clutch 13, a rear clutch 14, a low-reverse brake 15, a kickdown servo brake 16, an end clutch 17, and the like. An N-D control valve 18 to reduce the impact caused by shifting the selector lever from N range to D range is connected to the rear clutch 14. An N-R control valve 19 to reduce the impact caused by shifting the selector lever from N range to R range is connected to the low-reverse brake 15 via the first-second speed shift valve.
Also, a pressure control solenoid valve 20 is connected to a pressure control valve 21 to red
REFERENCES:
patent: 3048055 (1962-08-01), Borman et al.
patent: 4729266 (1988-03-01), Mishima et al.
patent: 4901603 (1990-02-01), Ishikawa
patent: 4942782 (1990-06-01), Kuwayama et al.
patent: 5074168 (1991-12-01), Ishikawa et al.
patent: 5086668 (1992-02-01), Fujiwara et al.
patent: 5159856 (1992-11-01), Yoshimura et al.
Jang Jaeduk
Lim Doki
Lim Kibeen
Hyundai Motor Company
Jensen Nathan
Marmor Charles A.
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