Self adjusting hydraulic tappet for heat engines

Claim 1

A self adjusting hydraulic tappet comprising a first open cup-shaped element (6) axially movable in a corresponding cylindrical seat formed in a cylinder head on an engine and having an upper end wall (7) cooperating with a cam and integral with a depending cylindrical side wall to define an cylindrical internal open area, a second-cup-shaped element housed inside said open area and axially slidable within the first element, said second element having an upper end wall (14) facing an inner surface of said upper end wall of said first element in order to define with this later a pressure chamber, the second element cooperating with a valve stem disposed within said cylindrical seat and immediately below the second element and at least one duct connecting to a fluid supply hole which passes through a side wall of the second element, a fluid supply opening in the first element aligned with said fluid supply hole, said fluid supply opening being connected to a pressurized fluid supply in the cylinder head, a one-way check valve at the other end of said duct and comprising a freely floating ball within a corresponding sealing seat cavity, the cavity being disposed in said upper end wall of said second element and open to and facing said inner surface of the end wall of the first element having a supply hole at its closed end to permit flow into said pressure chamber in response to higher pressure in the duct, the sealing cavity having a conical inner surface which defines the corresponding sealing seat of the ball the cavity being able to house substantially the whole ball, the supply hole having a substantially less diameter than that of the sealing seat, and said ball having a diameter which is both substantially greater than the diameter of the supply hole and substantially less than the upper width of the cavity so as to permit upward movement of the ball to allow fluid flow through the check valve and downward movement of the ball to engage the surface of the sealing cavity in sealing engagement when pressure is greater in the pressure chamber, the height of the pressure chamber being substantially less than the diameter of the ball in order to prevent the ball from escaping the sealing cavity.