| 摘要 |
PURPOSE:To compensate a viscosity drop due to a rise in oil temperature, by producing a free ball with synthetic resin being larger in a coefficient of thermal expansion than that of a valve cage, in case of a free ball valve as a check valve regulating a flow of oil inside a hydraulic tappet. CONSTITUTION:A cam follower 10 to be driven by a cam 6 rocks with an upper end of a plunger 22 of a hydraulic tappet 9 as a fulcrum and opens or closes a valve 5. The inside of this hydraulic tappet 9 is divided into an oil sump chamber 23 and a hydraulic chamber 21, and a free ball 29 capable of freely moving in an interconnecting passage 24 lying between both these chambers is being housed in a valve cage 28 regulating a dropping position of the ball 29. This free ball 29 is made up of synthetic resin being larger in a coefficient of thermal expansion than that of this metallic valve cage 28. When the follower 10 is depressed by the cam 6, oil inside the hydraulic chamber 21 tries to go back to the oil sump chamber 23 but this attempt is checked by the free ball 29, and its clearance stroke S should be reduced with a difference in thermal expansion in proportion as temperature goes higher, whereby a return increment due to a viscosity drop in the oil is compensated. |
