Interrelated power delivery controls – including engine control – Transmission control – Transmission controlled by engine
Reexamination Certificate
2000-12-29
2003-03-25
Graham, Matthew C. (Department: 3613)
Interrelated power delivery controls, including engine control
Transmission control
Transmission controlled by engine
C477S158000
Reexamination Certificate
active
06537180
ABSTRACT:
BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a hydraulic control system for automotive automatic transmissions.
(b) Description of the Related Art
Conventional automatic transmissions used in vehicles include a torque converter, a multi-stage gear shift mechanism connected to the torque converter, and a plurality of friction members actuated by hydraulic pressure for selecting one of the gear stages of the gear shift mechanism, the gear shift mechanism being realized through a planetary gearset. The friction elements are controlled to engaged and disengaged states by a hydraulic control system, which controls pressure generated in an oil pump, to change shift ratios of the planetary gearset.
When designing such an automatic transmission, a design target is first selected, then a design concept that is good in the aspects of performance, endurance, reliability, and productivity is chosen.
When the design concept is selected, an automatic transmission is developed in three sections, a mechanical section, a hydraulic control section, and an electronic control section.
The mechanical section (powertrain) is usually formed of a compound planetary gear set having at least two simple planetary gear sets. The hydraulic control section controlling the mechanical section includes a pressure regulating part for regulating hydraulic pressure generated from a fluid pump, a manual/automatic shift control part for determining a shift mode, a hydraulic control part for controlling hydraulic pressure to improve shift quality and shift responsiveness, a hydraulic pressure distributing part for properly distributing hydraulic pressure to each friction element, and a damper clutch control part for controlling the operation of a damper clutch of a torque converter.
The hydraulic pressure distribution is varied by solenoid valves that are on/off or duty controlled by a transmission control unit. According to the variation of the distribution, the operation of the friction elements are controlled, thereby realizing the shift control.
Such a powertrain and hydraulic control system has been developed in a variety of types by many different automakers.
However, in the conventional automatic transmission, one control mechanism is controlling at least two friction elements, and thus the friction elements cannot be independently controlled. In addition, since the friction elements are directly controlled by primary control pressure from solenoid valves, solenoid valves having a high capacity and a high degree of preciseness are required, increasing manufacturing costs and operation noise.
SUMMARY OF THE INVENTION
Therefore, the present invention has been made in an effort to solve the above problems.
It is a first objective of the present invention to provide a hydraulic control system that can make it possible to use small solenoid valves by independently controlling friction elements and employing an indirect control method whereby secondary control pressure is supplied to the friction elements, thereby reducing manufacturing costs as well as operation noise and vibration.
It is a second objective of the present invention to provide a hydraulic control system that can maintain optimal hydraulic pressure by employing a line pressure regulating solenoid valve, thereby improving the fuel consumption ratio.
It is a third objective of the present invention to provided a hydraulic control system that can minimize shift shock during a manual shifting operation while reducing vibration and fuel consumption ratio by realizing a neutral control in a stop state during driving.
To achieve the above objectives, the present invention provides a hydraulic control system for an automotive automatic transmissions comprising:
a pressure regulator for regulating hydraulic pressure generated by a fluid pump;
a pressure reducer having a reducing valve for reducing hydraulic pressure regulated by the pressure regulator;
a shift controller having a manual valve cooperating with a shift selector lever and connected to a plurality of range pressure lines;
a pressure controller comprising first, second and third solenoid valves for controlling control pressure reduced by the reducing valve, and first, second and third pressure control valves for controlling hydraulic pressure supplied from the manual valve, the first, second and third pressure control valves being independently controlled by control pressure supplied from the first, second and third solenoid valves, respectively;
a switching controller comprising a first switch valve for supplying hydraulic pressure from the first pressure control valve to one of first and second switching lines and a second switch valve for supplying hydraulic pressure from the third pressure control valve and the manual valve to first and second friction elements;
a fail-safer comprising a first fail-safe valve for supplying hydraulic pressure from the first switch valve and the manual valve to a friction element operated in low L and reverse R ranges, and a second fail-safe valve for supplying hydraulic pressure from the second pressure control valve to a friction element operated in second and fourth speeds; and
an N-R controller comprising an N-R control valve for supplying reverse pressure to a friction element operated in only a reverse R range.
The hydraulic control system may further comprise a fourth solenoid valve disposed between the reducing valve and the regulator valve.
The manual valve communicates with a line pressure line for receiving line pressure from the regulator valve, an N-D range pressure line connected to the first pressure control valve and a second fail-safe valve in neutral N and drive D ranges, a D range pressure line connected to the second pressure control valve, the first switch valve, the third pressure control valve, and the second switch valve in the drive D range, an L range pressure line connected to the first switch valve in the low L range, and an R range pressure line connected to the regulator valve, the second fail-safe valve, and the N-R control valve.
The first pressure control valve is provided with a first port for receiving reduced pressure from the reducing valve, a second port for receiving hydraulic pressure from the manual valve, a third port for supplying the hydraulic pressure fed through the second port to the first switch valve, and a fourth port for receiving control pressure from the first solenoid valve, the ports of the first pressure control valve being controlled by a valve spool installed in a valve body, the valve spool comprising a first land on which the hydraulic pressure fed through the first port acts, a second land on which the hydraulic pressure fed through the first port acts to open and close the second port, and a third land for selectively communicating the second port with the third port together with the second land, an elastic member being disposed between the valve body and the third land to bias the valve spool.
The second pressure control valve is provided with a first port for receiving the reduced pressure from the reducing valve, a second port for receiving hydraulic pressure from the manual valve, a third port for supplying the hydraulic pressure fed through the second port to the second fail-safe valve, and a fourth port for receiving control pressure from the second solenoid valve, the ports of the second pressure control valve being controlled by a valve spool installed in a valve body, the valve spool comprising a first land on which hydraulic pressure fed through the first port acts, a second land on which hydraulic pressure fed through the first port acts to selectively open and close the second port, and a third land for selectively communicating the second port with the third port together with the second land, an elastic member being disposed between the third land and the valve body to bias the valve spool.
The third pressure control valve is provided with a first port for receiving reduced pressure from the reducing valve, a second port for receiving hydrau
Jang Jae-Duk
Kim Tae-Kyun
Lee Chang-Wook
Lee Jin-Hee
Park Jong-Sool
Birch & Stewart Kolasch & Birch, LLP
Hyundai Motor Company
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