Patent ID: 6021751
Filing Date: 2000-02-08
Classification: F01L

Abstract:
A hydraulic valve lifter capable of forming at least a portion of an engine valve train between a cam and a valve, said lifter comprising:a follower having a cup-like shell with a peripheral outer wall generally parallel with an axis of reciprocation and having closed and open ends, an inner cylinder fixed within said shell parallel with the axis and spaced within the outer wall to define a first space therebetween, a baffle received in said follower shell and extending outward from the inner cylinder toward said outer wall to form, at least in part, a floor for said first space,said first space adapted to receive pressurized hydraulic fluid through inlet opening means in said peripheral outer wall;hydraulic means in the follower including a hollow piston guided in the cylinder and having a closed end facing away from the closed end of the shell, the closed ends of the shell and piston being adapted respectively for operative association in such valve train with the cam and valve, a plunger guided in the piston and having an open end operatively engagable with the closed end of the shell, the plunger defining a low pressure chamber;passage means continuously communicating the low pressure chamber with said first space for receiving hydraulic fluid from said first space, the plunger and piston defining a high pressure chamber within the closed end of the piston and connected through a non-return check valve with the low pressure chamber for delivering pressurized fluid to the high pressure chamber, a plunger spring urging the plunger toward engagement with the shell; anda lash spring stronger than the plunger spring but weaker than a valve spring of an associated valve, and disposed between the plunger and the closed end of the shell, the lash spring biasing the plunger against the force of the plunger spring a small distance away from the closed end of the shell when the associated valve is closed to provide lash in the valve train to prevent holding open of the associated valve during cold engine operation.