Switchable Valve Lifter Having a Mis-Assembly Indicator

Abstract

An improved SHVL for an internal combustion engine comprises an improved arrangement for locking a spring tower into a pin housing. The spring tower is provided with an annular OD groove as in the prior art. The pin housing ID groove is modified to have a two-step groove comprising two adjacent regions having different depths (different diameters) and having a distinct transition lip therebetween. A spring clip of the correct size seats properly in the spring tower groove and in the lesser-diameter pin housing groove, resulting in a correct overall length of the SHVL. Any oversize clip is caught between the lower lip of the spring tower groove and the transition lip of the two-step pin housing groove, resulting in a SHVL distinctly shorter than nominal, which is easily detected by either direct length measurement or a gauge.

Description

TECHNICAL FIELD[0001]The present invention relates to hydraulic valve lifters for internal combustion engines; more particularly, to a switchable valve-deactivating hydraulic valve lifter having an external lost motion spring and spring tower; and most particularly, to an improved arrangement for securing the spring tower to the pin housing that indicates when mis-assembly has occurred.BACKGROUND OF THE INVENTION[0002]Hydraulic valve lifters that are specially equipped for selective lost motion in an engine valvetrain to switchably deactivate an intake or exhaust valve are well known in the engine arts. In one form, such a “switchable hydraulic valve lifter” (SHVL) is provided with a lost motion coil spring that is captured on an end of the SHVL body by a spring tower. The spring tower extends within the body to mate with a pin housing that is slidably disposed within the body. When transverse locking pins in the pin housing are extended into engagement with the body, the SHVL is ri...

AI Technical Summary

Benefits of technology

[0007]Briefly described, an improved SHVL in accordance with the present invention includes an improved arrangement for locking a spring tower into a pin housing. The spring tower is provided with an annular OD groove as in the prior art. However, the pin housing ID groove is modified to provide a two-step groove comprising two adjacent regions having different depths (different diameters) and having a distinct transition lip therebetween. An expansion clip of the correct size seats properly in the spring tower groove and in the lesser-diameter pin housing groove, resulting in a secure mating and a correct overall length of the SHVL. Any oversize expansion clip is caught between the lower lip of the spring tower groove and the transition lip of the two-step pin housing groove, resulting in a SHVL approximately 1.0 mm shorter than nominal, which is easily detected by either direct length measurement or a gauge.

Problems solved by technology

The prior art assembly just described is especially vulnerable to failure from spring clips which are oversize.

If the ID of the clip is too large by as little as 0.15 mm, the clip may not fully lock into the tower groove, allowing spontaneous dis-assembly under use conditions in an engine, which is highly undesirable.

Unfortunately, there is no simple means at present for determining that this unsatisfctory condition exists in any SHVL after assembly.

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