192 clutches and power-stop control – Vortex-flow drive and clutch – Including drive-lockup clutch
Patent
1994-11-29
1997-01-07
Pitts, Andrea L.
192 clutches and power-stop control
Vortex-flow drive and clutch
Including drive-lockup clutch
192 331, 477169, F16D 3300, B60K 4110
Patent
active
055907512
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, and more particularly to the control system which can ensure a control of a damper clutch and minimize a loss of drive of an oil pump.
2. Description of Related Art
Generally, an oil pump driven by a driving force generates a hydraulic pressure for engaging a friction element which changes a speed ratio by selecting a gear stage of gear stages of a multi-stage transmission gear mechanism.
A hydraulic control system pressurized by an oil pump changes ports of shift valves in accordance with an operation of a solenoid valve or proportional control valves which are controlled to be turned ON/OFF or duty by a transmission control unit.
At this point, the line pressure is supplied to the selected friction member through the changed port to engage or release the friction member.
The oil pump generates the hydraulic pressure in proportion to the number of rotation of the engine. To establish a stable speed ratio change, the hydraulic control system should receive a regular hydraulic pressure. Thus, the hydraulic pressure generated from the oil pump is always controlled in a regular line pressure by a regulator valve.
The regulator valve is designed to control the hydraulic pressure in two modes, including a driving mode and a reverse mode.
However, since the hydraulic pressure becomes a fixed hydraulic pressure at the drive and reverse modes, respectively, when the shift lever is changed from the neutral "N" range to the drive "D" range, a shift impact occurs.
Accordingly, to decrease the shift impact caused by shifting the shift lever from the neutral "N" range to the drive "D" range, an N-D control valve is employed. However, the hydraulic control system employing the N-D control valve has a problem that the drive efficiency is deteriorated since the hydraulic control system always uses the fixed hydraulic pressure.
Additionally, since a reducing valve which reduces the hydraulic pressure to be lower than the line pressure to operate a pressure control valve and a damper clutch control valve is controlled by an elastic force of an elastic member and the line pressure, the operation of the reducing valve is unreliable.
Further, a damper clutch employed for increasing a mechanical efficiency of power transmission in a torque converter is engaged or released by a damper clutch control valve. Since a position of a valve spool of the damper clutch control valve is determined in accordance with the elastic force of the elastic member and a disparity in an area of lands of the valve spool, there is a problem that the valve spool may become stuck.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a hydraulic control system for an automatic transmission, which can minimize a loss of drive of an oil pump.
It is another object of the present invention to provide a hydraulic control system for an automatic transmission, which can ensure a control of a damper clutch and minimize a shift impact thereby increasing hydraulic pressure stability.
To achieve the above objects, the present invention provides a hydraulic control system for an automatic transmission, the system comprising: means with the hydraulic pressure in accordance with a vehicle's drive and reverse speed and transmitting a torque of a torque converter to a gear of a multi-stage transmission gear mechanism; from the oil pump to each shift valve by changing ports thereof in accordance with a position of a shift lever; oil pump to be lower than a line pressure; communicating with the manual valve, and changing the line pressure by opening or closing an exhaust port thereof, the opening or closing of the exhaust port is accomplished when the valve spool of the pressure regulating valve is moved by the hydraulic pressure which is reduced at the reducing valve; supplied from the manual valve to a rear clutch in a first forward speed ratio of a drive "D" range; or "ON" by a transmission control
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Jang Jaeduk
Lim Kibeen
Park Dong-hoon
Hyundai Motor Company
Pitts Andrea L.
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