Hydraulic control system for automatic transmission having torque converter with lock-up mechanism
This patent describes a hydraulic control system for an automatic transmission having a torque converter with a lock-up clutch, the automatic transmission having a plurality of forward speed ratios including a mth speed ratio and a m + 1th speed ratio, where: m is an integer, the hydraulic control system having a portion wherein a fluid pressure is present during operation in each of the mth speed ratio and m + 1th speed ratio, a lock-up valve including a spool movable between a clutch engagement position wherein the lock-up clutch is engaged and a clutch release position wherein the engagement of the lock-up clutch is released, and a spring biasing the spool toward the clutch release position; the spool of the lock-up valve having a first pressure acting area which is exposed to the fluid pressure in the portion of the hydraulic control system and being urged against the spring toward the clutch engagement position, the spool having a second pressure acting area; means for applying another fluid pressure to the second pressure acting area during shifting between the mth speed ratio and the m + 1th speed ratio to urge the spool toward the clutch release position.
- Assignee:
- Nissan Motor Co., Ltd., Yokohama
- Patent Number(s):
- US 4585100
- OSTI ID:
- 5543211
- Country of Publication:
- United States
- Language:
- English
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Hydraulic control system for automatic transmission having torque converter with lock-up mechanism