| 摘要 |
A two-step variable valve lift system for an internal combustion engine is provided to increase engine output and reduce pumping loss by increasing valve lifting in a high speed operating section of the engine. A two-step variable valve lift system for an internal combustion engine includes a rocker arm(10), a pair of guides, a pair of rocker shaft units(22), a spring, and a hydraulic pressure supply unit. The rocker arm has a front end attached with a roller(42) contacting a cam(40), a rear end connected to a valve(44), and a center with a first mounting hole(12) for a pivot. The guides are arranged in the vicinity of both sides of the rocker arm and mounted to a cylinder head by bolts, and have inner surfaces with second mounting holes. The rocker shaft unit includes a connector, a high valve lift pivot shaft(16) formed integrally with a front end of the connector and inserted into the first mounting hole of the rocker arm, and a low valve lift pivot shaft(18) formed integrally with a rear end of the connector and inserted into the second mounting hole of the guide. The spring is fitted into the first mounting hole, and interposed between the high valve lift pivot shafts of the rocker shaft units. The hydraulic pressure supply unit is connected to the guides so as to push the low valve lift pivot shaft inserted in the second mounting hole by oil pressure. |
