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Early exhaust valve opening control system and method

  • US 5,937,807 A
  • Filed: 03/30/1998
  • Issued: 08/17/1999
  • Est. Priority Date: 03/30/1998
  • Status: Expired due to Term
First Claim
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1. An exhaust valve system for an internal combustion engine having a crankshaft mounted for rotation, at least one engine piston operatively connected to the crankshaft for reciprocal movement within a cylinder through cyclical successive compression and expansion strokes, an exhaust system and a turbocharger positioned in the exhaust system, comprising:

  • at least one exhaust valve reciprocally mounted in the engine for movement between open and closed positions;

    an exhaust valve actuating means for moving said at least one exhaust valve between said open position and said closed position, said exhaust valve actuating means including an exhaust valve opening control means for varying the timing of the opening of said at least one exhaust valve during engine operation, said exhaust valve opening control means operable in a normal timing mode for permitting normal opening of said at least one exhaust valve at a normal opening crank angle prior to an end of the expansion stroke and subsequently permitting normal closing of said at least one exhaust valve at a normal closing crank angle, and in an advanced timing mode during at least one of idle engine conditions and low load engine conditions for advancing the timing of the opening of said at least one exhaust valve to an advanced opening crank angle substantially prior to said normal opening crank angle while maintaining the timing of normal closing of said at least one exhaust valve at said normal closing crank angle so as to increase the speed of the turbocharger during operation in said advanced timing mode.

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