Patent Number: 6,305,758

Title: Electro-hydraulic actuator for motor vehicle brake

Abstract: An electro-hydraulic actuator for a motor vehicle brake-by-wire brake system including a housing, a piston bore in the housing, a T-shaped piston in the piston bore, and an electric motor connected to the piston through a speed reducer. The T-shaped piston includes a disc-shaped head in the piston bore and a tubular stem perpendicular slidable in and out of the piston bore through a sealed guide in the bottom of the piston bore. The top side of the piston head opposite the stem constitutes a large effective area of the piston for rapidly expelling a relatively large volume of fluid from the piston bore in a low pressure interval of operation the actuator. When the fluid pressure in the piston bore exceeds a transition pressure, a transition valve opens a bypass passage to the piston bore behind the piston head so that the same fluid pressure reacts against the bottom side of the piston head around the stem. A high pressure interval of operation of the electro-hydraulic actuator then ensues in which the effective area of the piston is reduced to the area of the cross-sectional profile of the stem.

Inventors: Hageman; John Benjamin (Vandalia, OH), Schenk; Donald Edward (Vandalia, OH), Shaw; Schuyler Scott (Dayton, OH)

Assignee: Delphi Technologies, Inc.

International Classification: B60T 8/40 (20060101); B60T 13/74 (20060101); B60T 13/00 (20060101); B60T 8/32 (20060101); B60T 008/42 ()

Expiration Date: 10/23/2018