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Hydraulic control device for automatic transmission

  • US 8,123,642 B2
  • Filed: 12/02/2009
  • Issued: 02/28/2012
  • Est. Priority Date: 12/25/2008
  • Status: Active Grant
First Claim
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1. A hydraulic control device for an automatic transmission, comprising:

  • a hydraulic pressure source;

    a plurality of friction engagement elements;

    a line pressure regulating valve that regulates hydraulic pressure from the hydraulic pressure source to a predetermined line pressure;

    a plurality of operation pressure regulating valves that regulate the line pressure as operation pressure for a hydraulic servo of the friction engagement element;

    a maximum pressure conducting circuit that guides a maximum pressure among the operation pressures regulated by the plurality of operation pressure regulating valves to the line pressure regulating valve, whereinthe friction engagement elements are engaged and released to achieve a plurality of forward speeds and a reverse speed, andthe line pressure regulating valve regulates the line pressure during forward travel based on the maximum operation pressure guided by the maximum pressure conducting circuit, and regulates the line pressure during reverse travel based on the operation pressure input from a specific operation pressure regulating valve among the plurality of operation pressure regulating valves.

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