| 摘要 |
A two mode valve lifter for Diesel engines which varies the compression ratio between higher for cold starting and other selected operating conditions, and lower for warmed-up running. This is accomplished during engine starting and selected other conditions by causing the intake valve to close early (near bottom center), providing for example, up to three ratios additional compression. The invention incorporates a conventional valve lifter packaged within a sleeve, the sleeve being moved by the engine cam. In its conventional operating mode, the sleeve is rigidly attached to the lifter and the cam moves the assembly to lift the valve in the ordinary manner. When the sleeve is not attached, partial lost motion occurs, causing the valve to open later and close earlier. In the modified mode and as needed, optional damping can be introduced to allow the valve to open and close gradually and quietly. Similarly, a two mode valve lifter which retains additional exhaust gas in the cylinder to assist cold starting and warm-up by closing the exhaust valve earlier can be incorporated either alone or in combination with the intake two mode lifter.
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