Hydraulic self adjusting valve tappet, e.g. for IC engine - mfd. by in situ injection blow moulding plastic reservoir for simple fixing and reliable fluid sealing

摘要

Valve plunger (1) with hydraulic adjustment (2) in which the cavity (3) for hydraulic fluid is formed by injection moulding a thermoplastic into the plunger (1) and inflating it by gas pressure to form a hollow plastics lining (4) (in situ injection blow moulding). Injection may be through an opening (5) in the plunger wall (1b), which after moulding is trimmed flush to form the inlet for hydraulic fluid. The space (2') for the adjustment unit (2) may be formed during moulding by a sliding core pin which may be spaced from the plunger head (1a) so that plastic flows between. The plastic is subsequently removed mechanically to form the space (2') and ports (6) on one or both sides, which connect the hydraulic fluid in cavity (3) to the adjustment unit (2). The cavity may be on one side (as shown) or both sides of the adjustment unit; in the latter case an inlet port (5) may be formed at each side. The gas for inflation may be introduced through the usual blowing pin in port(s) (6), e.g. in the core pin, or in the double-sided construction, through the second port (5). USE/ADVANTAGE - Self-adjusting tappet for internal combustion (IC) engine. Avoids expensive fixing of inserted plastic part and sealing of fluid space, with only necessary inlet and outlet connections.