Hydraulic control system for automatic transmission having torque converter with lock-up mechanism
This patent describes a hydraulic control system for an automatic transmission for a vehicle having a torque converter with a lock-up clutch, the automatic transmission having forward speed ratios including a m th speed ratio and a m + 1 th speed ratio, where: m is an integer, the hydraulic control system having a first portion wherein a first fluid pressure is present during operation in each of the m th speed ratio and the m + 1 th speed ratio, and a second portion wherein a second fluid pressure is present during operation in one of the m th speed ratio and m + 1 th speed ratio and absent during operation in the other 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 clutch is released, and a spring biasing the spool toward the clutch release position, the spool of the lock-up valve having a pressure acting area which is exposed to the first fluid pressure and being urged against the spring toward the clutch engagement position; means responsive to the second fluid pressure for applying the second fluid pressure to the pressure acting area instead of the first fluid pressure.
- Assignee:
- Nissan Motor Co., Ltd., Yokohama
- Patent Number(s):
- US 4585102
- OSTI ID:
- 5757200
- Country of Publication:
- United States
- Language:
- English
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