Clutch with dual area piston and independent pressure control

Abstract

The present invention provides a clutch having two pistons, a first piston defining a first, smaller area and a second piston, defining a second, larger area. The separate pistons are independently provided with flows of pressurized hydraulic fluid from first and second independent modulatable control valves. Engagement of the clutch may be rapid by providing hydraulic fluid to the smaller area piston, provide greater engagement force by providing hydraulic fluid to the larger area piston or a combination of speed and force by utilizing modulated or unmodulated flows of hydraulic fluid to both pistons.

Description

technical field [0001] The present invention relates to a clutch having dual area pistons, and more particularly, to a clutch having two pistons of different areas and dual pressure valves for providing independent control of the pressure on each piston. The clutch has particular application in multi-speed automatic transmissions for motor vehicles. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. [0003] The current design class of multi-speed automatic transmissions includes multiple planetary gear assemblies having a sun gear, planet carrier and ring gear interconnected by a permanent connection and selectively connected by a clutch or by a brake Make a fixed connection or ground (ie, connect to a fixed object). Clutches and brakes are typically engaged or actuated by hydraulic fluid pressure. [0004] The speed and force at which a clutch or br...

AI Technical Summary

Problems solved by technology

If this happens during a gear change, it can lead to poor maximum torque control

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