Patent ID: 8079210
Filing Date: 2011-12-20
Classification: F01L,F01N,F02D,Y02T

Abstract:
1. An engine comprising: a first exhaust valve and a second exhaust valve; a first exhaust passage and a second exhaust passages opened and closed by the first and second exhaust valves, respectively; a first catalyst disposed in the first exhaust passage; a second catalyst disposed in the second exhaust passage so as to be located upstream of the first catalyst; a variable valve operating mechanism configured to adjust lifting amounts of the first and the second exhaust valves between approximately zero and a maximum lifting amount; and a lifting amount control unit configured to control lifting amounts of the first and the second exhaust valves with the variable valve operating mechanism such that an exhaust gas amount passing through the second exhaust passage is larger than an exhaust gas amount passing through the first exhaust passage at least during start-up of the engine, and such that the exhaust gas amount passing through the first exhaust passage is larger than the exhaust gas amount passing through the second exhaust passage at least in a range of high-speed rotation and large-load operation of the engine after completion of a warm-up operation of the engine; wherein the second catalyst is provided in a cylinder head and is disposed within a second exhaust port which defines a portion of the second exhaust passage; and the first exhaust valve includes two first exhaust valves disposed side-by-side in a camshaft direction, and the second exhaust valve is disposed between the two first exhaust valves.