Switchable valve train device having a single locking pin

Abstract

A switchable valve train device including a pin housing slidably disposed in a body and having a transverse bore. A stepped plug in the transverse bore extends beyond the pin housing to engage a slot in the body to prevent rotation of the pin housing. The upper end of the slot limits travel of the pin housing. The plug is a seat for a compression spring. A locking pin is disposed in the transverse bore against the spring to selectively engage a locking port in the body, the locking pin and the locking port have mating flats to distribute the load. Mechanical lash is set by use of a gage tool during assembly, allowing selection of a locking pin of appropriate thickness. The device may be, for example, a switchable hydraulic lash adjuster or a switchable valve lifter.

1 . A switchable valve train device for selective switching of a valve train in an internal combustion engine, the device comprising:
 a) a body having a locking port formed in a first body wall and a longitudinal slot formed in a second and opposite body wall, wherein said locking port includes a locking ledge;   b) a pin housing slidingly disposed in said body and having a transverse bore;   c) a plug slidably disposed in said transverse bore and having a plug portion extending into said longitudinal slot for preventing rotation of said pin housing within said sub-assembly body; and   d) a locking pin slidably disposed in said transverse bore and having a locking flat for selectively engaging said locking ledge.   
   
   
       2 . A switchable valve train device in accordance with  claim 1  further comprising a return spring disposed in said transverse bore between said plug and said locking pin for urging said locking pin into said locking port. 
   
   
       3 . A switchable valve train device in accordance with  claim 1   wherein said pin housing assumes a first axial position when said locking pin flat is engaged with said locking ledge, and   wherein said pin housing assumes a second axial position when said portion of said plug extending into said slot is engaged with an end of said slot, and   wherein the difference between said first and second axial positions defines the internal mechanical lash within said device.   
   
   
       4 . A switchable valve train device in accordance with  claim 3  wherein said locking pin has a thickness at said locking flat such that said internal mechanical lash is set at a predetermined value. 
   
   
       5 . A switchable valve train device in accordance with  claim 1  wherein said device is a switchable hydraulic lash adjuster. 
   
   
       6 . A switchable valve train device in accordance with  claim 1  wherein said device is a switchable hydraulic valve lifter. 
   
   
       7 . A switchable hydraulic lash adjuster for selective deactivation of a valve train in an internal combustion engine, comprising:
 a) a body having a locking port formed in a first body wall and a longitudinal slot formed in a second and opposite body wall, wherein said locking port includes a locking ledge;   b) a pin housing slidingly disposed in said body and having a transverse bore;   c) a plug slidably disposed in said transverse bore and having a plug portion extending into said longitudinal slot for preventing rotation of said pin housing within said body; and   d) a locking pin slidably disposed in said transverse bore and having a locking flat for selectively engaging said locking ledge.   
   
   
       8 . A switchable hydraulic lash adjuster in accordance with  claim 7  comprising a return spring disposed in said transverse bore between said plug and said locking pin for urging said locking pin into said locking port. 
   
   
       9 . An internal combustion engine, comprising a switchable hydraulic lash adjuster for selective deactivation of a valve train in an internal combustion engine, wherein said deactivating hydraulic lash adjuster includes:
 a sub-assembly body disposable in a bore in said engine for receiving said deactivating hydraulic lash adjuster and having a locking port formed in a first body wall and a longitudinal slot formed in a second and opposite body wall, wherein said locking port includes a locking ledge,   a pin housing slidingly disposed in said body and having a transverse bore and having an axial bore containing a hydraulic lash adjustment mechanism,   a plug slidably disposed in said transverse bore and having a plug portion extending into said longitudinal slot for preventing rotation of said pin housing within said sub-assembly body,   a locking pin slidably disposed in said transverse bore and having a flat for selectively engaging said locking ledge, and   a return spring disposed in said transverse bore between said plug and said locking pin for urging said locking pin into said locking port.   
   
   
       10 . A method for setting internal mechanical lash of a switchable valve train device to a desired value wherein the device includes a body having a locking port and a longitudinal slot, wherein said locking port includes a locking ledge; a pin housing slidingly disposed in said body and having a transverse bore; a plug disposed in said transverse bore and having a plug portion extending into said longitudinal slot; and a locking pin slidably disposed in said transverse bore and having a locking flat for engaging said locking ledge, the method comprising the steps of:
 a) inserting said plug into said transverse bore in said pin housing;   b) inserting said pin housing and said plug into said body until said transverse bore is adjacent said locking port;   c) inserting a gage tool through said locking port into said transverse bore to seat a portion of said plug into said longitudinal slot;   d) moving said pin housing axially within said body until a flat on said gage tool engages said locking ledge in said locking port, defining a first axial position of said pin housing;   e) moving said pin housing axially in said body until said plug portion in said longitudinal slot engages an end of said slot, defining a second axial position of said pin housing;   f) observing the axial distance between said first position and said second position;   g) removing said gage tool from said transverse bore and said locking port;   h) providing a selected locking pin having a thickness at said locking pin flat such that the difference between said thickness and said observed axial distance is equal to said desired value of internal mechanical lash; and   i) inserting said selected locking pin into said transverse bore through said locking port.   
   
   
       11 . The method in accordance with  claim 10  further including the steps of:
 a) inserting a return spring into said transverse bore through said locking port before step i) and;   b) displacing said locking pin in said transverse bore to reseat said plug portion in said longitudinal slot.   
   
   
       12 . The method in accordance with  claim 10  further including the step, prior to the removing step, of moving the gage tool away from the locking ledge by raising the pin housing, without disassembling the pin housing from the body, to permit the gage tool to be removed from the transverse bore.