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Method and apparatus to control logic valves for hydraulic flow control in an electro-mechanical transmission

  • US 8,406,945 B2
  • Filed: 10/10/2008
  • Issued: 03/26/2013
  • Est. Priority Date: 10/26/2007
  • Status: Expired due to Fees
First Claim
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1. A method for controlling an electro-mechanical transmission comprising first and second electric machines and a hydraulic circuit having a plurality of flow management valves and pressure control solenoids operative to actuate a plurality of clutches and a plurality of pressure monitoring devices adapted to monitor said hydraulic circuit, said transmission operative in fixed gear and continuously variable operating range states through selective actuation of said clutches, the method comprising:

  • operating said hydraulic circuit as a multi-layered control system, wherein a first layer comprises said flow management valves selectively permitting a hydraulic flow to a hydraulic cooling circuit for said electric machines and to said clutches and a second layer comprises said pressure control solenoids varying pressure of said hydraulic flow;

    monitoring a current hydraulic circuit oil temperature;

    monitoring a current state of said flow management valves;

    monitoring a command for cooling of said electric machines;

    monitoring a selected transition from a current transmission operating range state to a desired transmission operating range state;

    utilizing a state machine defining possible transitions for said flow management valves to determine a sequence for controlling positions of said flow management valves to achieve said desired transmission operating range state based upon said current hydraulic circuit oil temperature, said current state of said flow management valves, said command for cooling of said electric machines, and said desired transmission operating range state, wherein the utilizing said state machine to determine said sequence comprises, determining a desired state of said flow management valves based upon said desired transmission operating range state; and

    applying valve logic-based rules to determine said sequence for controlling positions of said flow management valves based upon said desired state of said flow management valves; and

    controlling said flow management valves based upon said sequence.

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