GB1241634A - Valve tappet for engines having an overhead camshaft - Google Patents

Abstract

1,241,634. Hydraulic tappets. MOTOMAK MOTORENBAU MASCHINEN -UND WERKZEUGFABRIK, KONSTRUKTIONEN G.m.b.H. 18 April, 1969 [19 April, 1968; 22 March, 1969], No. 20033/69. Heading F2K. Hydraulic tappet for direct interposition between a cam 7 and a valve stem 8 of an overhead cam-shaft I.C. engine comprises a tappet body 1 slidable in a guide 4 and housing an annular fluid reservoir 14 which surrounds an automatic slack take-up device formed by a plunger 2 in a cylinder 30 the pressure chamber 3 of which is connected via a non-return valve 19 to the reservoir 14, which in turn is supplied with oil from the engine lubrication system. The cam bears on a wear resistant plate 6 at the top of the tappet. The valve stem 8 abuts the plunger 2. While the tappet engages the base circle 20 of the cam, oil from a line 10 can enter the reservoir 14 via a gallery 12 and a port 13 in the tappet body 1. A port 15 in the cylinder 30 opens to an annular groove 16 round the plunger 2 to feed the non-return valve 19, and faces away from the port 13 to prevent air from entering the pressure chamber 3. When the tappet is deflected by the cam rise, the port 13 is opened to the atmosphere, via a chamfer 23, to prevent "pumping" of the tappet, and a port 26 is uncovered to direct oil on to the cam and the plate 6. The tappet body and cylinder are formed integrally by deep drawing. An alternative tappet body (Fig. 2, not shown) engages the cam with its upper end, the outer wall and the cylinder depending from said upper end. A closure plate (29) seals the lower end of the reservoir.