Discrete lost motion device

Abstract

A discrete lost motion device for use in a valve train of an internal combustion engine comprises a housing having a housing bore extending longitudinally into the housing and a second end having a housing contact surface configured to engage a corresponding contact surface of a first valve train component. A plunger slidably is disposed in the housing bore is controllable between a first state in which the plunger rigidly extends out of the housing bore and a second state in which the plunger is permitted to reciprocate within the housing bore, the plunger further comprising an end having a plunger contact surface configured to engage a corresponding contact surface of a second valve train component. The housing contact surface and the plunger contact surface are configured to support the discrete lost motion device between the first and second valve train components.

What is claimed is: 
     
         1 . A discrete lost motion device for use in a valve train of an internal combustion engine, the valve train having at least a first and a second valve train component, the lost motion device comprising:
 a housing having a housing bore extending longitudinally into the housing from a first end of the housing, the housing further comprising a second end having a housing contact surface configured to engage a corresponding contact surface of the first valve train component; and   a plunger slidably disposed in the housing bore through the first end of the housing and controllable between a first state in which the plunger rigidly extends out of the housing bore and a second state in which the plunger is permitted to reciprocate within the housing bore, the plunger further comprising an end having a plunger contact surface configured to engage a corresponding contact surface of the second valve train component,   wherein the housing contact surface and the plunger contact surface are configured to support the discrete lost motion device between the first and second valve train components.   
     
     
         2 . The discrete lost motion device of  claim 1 , wherein the housing contact surface and the plunger contact surface are configured to permit rotation of the discrete lost motion device relative to the first valve train component or the second valve train components or both. 
     
     
         3 . The discrete lost motion device of  claim 2 , wherein either of the housing contact surface and the plunger contact surface may comprise a convex contact surface or a concave contact surface. 
     
     
         4 . The discrete lost motion device of  claim 3 , wherein either of the housing contact surface and the plunger contact surface may comprise a spherical contact surface. 
     
     
         5 . The discrete lost motion device of  claim 1 , wherein either the second end of the housing or the end of the plunger comprises a hydraulic passage configured to receive hydraulic fluid for controlling the plunger between its first and second states. 
     
     
         6 . The discrete lost motion device of  claim 5 , further comprising:
 a hydraulically controlled locking mechanism configured to, in the first state, lock the plunger relative to the housing and, in the second state, to unlock the plunger relative to the housing,   wherein the hydraulic passage in is fluid communication with the hydraulically controlled locking mechanism.   
     
     
         7 . The discrete lost motion device of  claim 6 , wherein the hydraulically controlled locking mechanism defaults to a locked state and application of hydraulic fluid via the hydraulic passage causes an unlocked state of the hydraulically controlled locking mechanism. 
     
     
         8 . The discrete lost motion device of  claim 6 , wherein the hydraulically controlled locking mechanism defaults to an unlocked state and application of hydraulic fluid via the hydraulic passage causes a locked state of the hydraulically controlled locking mechanism. 
     
     
         9 . The discrete lost motion device of  claim 6 , wherein the hydraulically controlled locking mechanism comprises an inner plunger slidably disposed in a longitudinal bore formed in the plunger and radially extending locking elements disposed in radial openings formed in the plunger, and wherein the housing bore comprises an annular recess engaged by the locking elements when the locking elements extend out of the radial openings. 
     
     
         10 . The discrete lost motion device of  claim 9 , wherein a longitudinal extent of the annular recess is greater than a thickness of the locking elements. 
     
     
         11 . The discrete lost motion device of  claim 9 , wherein a longitudinal extent of the annular recess is at least large enough to accommodate a maximum separation between the first and second valve train components when the elements extend out of the radial openings and engage the annular recess. 
     
     
         12 . The discrete lost motion device of  claim 5 , further comprising:
 a check valve in fluid communication with the hydraulic passage and configured to establish a volume of locked hydraulic fluid between the housing and the plunger.   
     
     
         13 . The discrete lost motion device of  claim 12 , wherein the check valve is deployed in a control valve upstream of the discrete lost motion device. 
     
     
         14 . The discrete lost motion device of  claim 12 , wherein the check valve is deployed within the discrete lost motion device. 
     
     
         15 . The discrete lost motion device of  claim 14 , further comprising:
 a biased pin arranged to open the check valve when hydraulic fluid is not being supplied via the hydraulic passage and to permit closure of the check valve when hydraulic fluid is being supplied via the hydraulic passage.   
     
     
         16 . The discrete lost motion device of  claim 1 , further comprising:
 a plunger spring biasing the plunger out of the plunger bore.   
     
     
         17 . The discrete lost motion device of  claim 16 , wherein the plunger spring is disposed within the housing bore. 
     
     
         18 . The discrete lost motion device of  claim 16 , wherein the plunger spring is disposed outside of the housing. 
     
     
         19 . The discrete lost motion device of  claim 1 , wherein travel of the plunger out of the housing bore is limited. 
     
     
         20 . The discrete lost motion device of  claim 1 , wherein either the housing contact surface or the plunger contact surface is configured to be attached to a corresponding one of the first valve train component or the second valve train component.