Patent ID: 6039017
Filing Date: 2000-03-21
Classification: F01L

Abstract:
A hydraulic lash adjuster capable of forming a pivot for a member of an engine valve train connecting a cam and a valve, said adjuster comprising:a cup-shaped body with a peripheral outer wall defining an internal first cylinder formed around an axis and having closed and open ends;a hollow piston reciprocable in the cylinder and extending out through the open end of the body, the piston having a rounded outer end for acting as a pivot and an open inner end having an inward extension defining a second cylinder spaced from the closed end of the first cylinder;hydraulic means in the body including a plunger reciprocable within the second cylinder and having an open outer end operatively engagable with the open end of the piston for holding the piston outward during valve actuation, the plunger defining a low pressure chamber for receiving hydraulic fluid supplied from the engine, the plunger being spaced from the closed end of the first cylinder and defining therewith a high pressure chamber connected through a non-return check valve with the low pressure chamber for delivering fluid to the high pressure chamber,a take up spring acting between the closed end of the first cylinder and the piston and urging the piston outward from the first cylinder to take up lash in the associated valve train; anda lash spring disposed between the plunger and the piston, the lash spring biasing the plunger a small distance away from the open end of the piston when the associated valve is closed to provide selected lash in the lash adjuster to prevent compressed fluid in the high pressure chamber from holding the valve open during cold engine operation.