Switchable Valve Lifter Having a Mis-Assembly Indicator
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.
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 INVENTIONHydraulic 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 rigid and acts to faithfully translate the rotary motion of a cam lobe into reciprocal motion of an associated valve stem. When the locking pins are withdrawn into the pin housing, the cam lobe causes the pin housing to reciprocate within the body without such translation (in “lost motion” of the cam lobe). That is, the body moves in a first direction responsive to the cam lobe, against the force of the lost motion spring while the pin housing remains stationary. Thus, the associated valve becomes “deactivated”.
During assembly of a SHVL, the spring tower enters the end of the pin housing, the lost motion spring being in compression, and is retained therein by an expandable spring clip that is engaged in both an external annular groove in the spring tower and an internal annular groove in the pin housing, the clip being captured between the two components. Assembling these components requires that the clip be expanded around the spring tower (into the pin housing groove), allowing the spring tower to pass through the spring clip. The clip then must snap into the annular groove of the spring tower and also lock into the groove of the pin housing when the compression of the spring is reduced. The annular groove in the pin housing has a sloping side to accommodate slight variations in clip diameter.
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.
What is needed in the art is a means for recognizing, in a population of manufactured SHVLs, any SHVLs have been mis-assembled with an unacceptably large clip, to permit the faulty SHVLs to be segregated and reworked before being installed into engines.
It is a principal object of the present invention to permit simple recognition of a mis-assembled SHVL.
SUMMARY OF THE INVENTIONBriefly 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.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.
DESCRIPTION OF THE PREFERRED EMBODIMENTSReferring to
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While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.
Claims
1. A switchable hydraulic valve lifter for an internal combustion engine, comprising:
- a) a spring tower having an annular groove formed in an outer surface thereof;
- b) a pin housing having a bore for receiving said spring tower and having a two-step annular groove formed in an inner surface thereof; and
- c) an expansion clip disposed in said spring tower annular groove and said pin housing two-step annular groove for locking said spring tower into said pin housing bore,
- wherein said two-step annular groove is defined by a first groove having a first diameter, a second groove adjacent said first groove and having a second and larger diameter,
- wherein a correctly-sized expansion clip is accepted into said spring tower annular groove and into said pin housing first groove, resulting in said switchable hydraulic valve lifter having a first overall length, and
- wherein an oversized expansion clip is prevented from entering said pin housing first groove, resulting in said switchable hydraulic valve lifter having a second overall length.
2. A switchable hydraulic valve lifter, in accordance with claim 1, wherein said two-step annular groove includes a transition lip formed between said first and second grooves.
3. A switchable hydraulic valve lifter, in accordance with claim 1, wherein said first overall length is greater than said second overall length.
4. An internal combustion engine, comprising a switchable hydraulic valve lifter including
- a spring tower having an annular groove formed in an outer surface thereof,
- a pin housing having a bore for receiving said spring tower and having a two-step annular groove formed in an inner surface thereof, and
- an expansion clip disposed in said spring tower annular groove and said pin housing two-step annular groove for locking said spring tower into said pin housing bore,
- wherein said two-step annular groove is defined by a first groove having a first diameter, a second groove adjacent said first groove and having a second and larger diameter,
- wherein a correctly-sized expansion clip is accepted into said spring tower annular groove and into said pin housing first groove, resulting in said switchable hydraulic valve lifter having a first overall length, and
- wherein an oversized expansion clip is prevented from entering said pin housing first groove, resulting in said switchable hydraulic valve lifter having a second overall length.
5. A method for sorting mis-assembled switchable hydraulic valve lifters from a population of switchable deactivating hydraulic valve lifters, comprising the steps of:
- a) establishing a predetermined correct overall length for a correctly-assembled switchable hydraulic valve lifter;
- b) measuring the overall length of each of said switchable hydraulic valve lifters; and
- c) segregating any switchable hydraulic valve lifters having an overall length other than said predetermined correct overall length.
Type: Application
Filed: Apr 29, 2009
Publication Date: Nov 4, 2010
Inventors: Carl R. Kangas (Sand Lake, MI), William D. Bauman (Dorr, MI)
Application Number: 12/432,300