Electromechanical valve actuator beginning of stroke damper

Abstract

An electromechanical valve actuator having a beginning of stroke damper to damp the impact between the armature stem and the valve stem as the valve is opened. The beginning of stroke damper includes an armature stem defining a stem passage and a valve stem including a lash compensator defining a cavity communicating with the stem passage. An oil pocket may be provided within the cavity to absorb the impact of the armature stem before the armature stem contacts the valve stem as the valve is opened. The lash compensator is configured so that the cavity has a discharge rate sufficient to ensure that the cavity completely drains at approximately the time the engine valve reaches the full open position.

1 . A beginning of stroke damper for an electromechanical valve actuator comprising: 
 an armature stem;    a valve stem;    a stem passage defined by one of said armature stem and said valve stem; and    a lash compensator defining a cavity, said cavity being in constant fluid communication with said stem passage.    
     
     
         2 . The beginning of stroke damper of  claim 1  wherein said lash compensator is coupled to one of said valve stem and said armature stem, said lash compensator further including an annular sleeve and wherein said annular sleeve and the other of said valve stem and said armature stem define said cavity.  
     
     
         3 . The beginning of stroke damper of  claim 2  wherein at least one of said annular sleeve and said armature stem includes grooves for facilitating fluid flow between said armature stem and said annular sleeve.  
     
     
         4 . The beginning of stroke damper of  claim 1  further including a stem plug coupled to one of said armature stem and valve stem, said stem plug defining a fluid passage aligned with said stem passage and wherein said stem plug further includes a one way fluid valve.  
     
     
         5 . The beginning of stroke damper of  claim 1  wherein said stem passage is defined by said valve stem and said valve stem further includes a valve stem opening and a valve stem exit in communication with said stem passage.  
     
     
         6 . The beginning of stroke damper of  claim 1  wherein fluid within said cavity is capable of flowing from said cavity into said stem passage.  
     
     
         7 . An electromechanical valve actuator comprising: 
 a stem defining a stem passage; and    an annular sleeve cooperating with said stem to define a cavity capable of holding a fluid and wherein fluid within said cavity is capable of flowing from said cavity into said stem passage.    
     
     
         8 . The electromechanical valve actuator of  claim 7  wherein said armature stem includes a lower end and an upper end, said lower end of said armature stem and said valve stem defining a lash gap therebetween.  
     
     
         9 . The electromechanical valve actuator of  claim 7  further including an armature stem and a valve stem aligned with said armature stem wherein one of said armature stem and said valve stem is coupled to said annular sleeve and the other of said armature stem and said valve stem fits within said annular sleeve and defines an annular gap between said other stem and said annular sleeve.  
     
     
         10 . The electromechanical valve actuator of  claim 9  wherein said fluid passage has a first cross-sectional area and said annular gap has a second cross-sectional area, said second cross-sectional area being approximately equal to or greater than said first cross-sectional area.  
     
     
         11 . The electromechanical valve actuator of  claim 9  further including: 
 an armature electromagnet opposing a valve electromagnet with an armature plate disposed therebetween for movement between said armature electromagnet and said valve electromagnet; and    a cavity defined by said armature stem, said valve stem and said annular sleeve, said cavity configured to hold a fluid pocket for dampening impact forces between said armature stem and said valve stem as said armature plate moves from said armature electromagnet to said valve electromagnet.    
     
     
         12 . The electromechanical valve actuator of  claim 9  further including: 
 an armature electromagnet opposing a valve electromagnet with an armature plate disposed therebetween for movement between said armature electromagnet and said valve electromagnet;    a cavity defined by said armature stem, said valve stem and said annular sleeve, said cavity configured to hold a fluid pocket for dampening impact forces between said armature stem and said valve stem as said armature plate moves from said armature electromagnet to said valve electromagnet; and    wherein said valve has an open and a closed position and wherein said annular gap has a cross-sectional area sized for discharging fluid from said cavity so that said armature stem contacts said valve stem approximately before said valve reaches said open position as said armature plate moves from said armature electromagnet to said valve electromagnet.    
     
     
         13 . The electromechanical valve actuator of  claim 12  wherein said annular gap has a cross-sectional area sized to prevent said valve from moving from said closed position while said armature plate is secured against said armature electromagnet.  
     
     
         14 . A beginning of stroke damper for a lever electromechanical actuator comprising: 
 a valve stem having a valve stem opening, a valve exit and a stem passage therebetween;    a spring assembly having an armature spring retainer and a valve spring retainer coupled to said valve stem;    a lash compensator coupled to one of said armature spring retainer and said valve spring retainer, said lash compensator and the other of said armature spring retainer and said valve spring retainer defining a cavity therebetween, said cavity in fluid communication with said valve stem passage.    
     
     
         15 . The beginning of stroke damper of  claim 14  further including a connecting rod coupled to said armature spring retainer and wherein said lash compensator and one of said valve stem and said connecting rod define an annular groove therebetween, said annular groove having a cross-sectional area greater than or equal to said valve stem passage.  
     
     
         16 . The beginning of stroke damper of  claim 15  further including a connecting rod coupled to said armature spring retainer and wherein said lash compensator and one of said valve stem retainer and said armature stem retainer define an annular groove therebetween, said annular groove having a cross-sectional area greater than or equal to said valve stem passage.  
     
     
         17 . A beginning of stroke damper for an electromechanical valve actuator capable of moving a valve between an open and closed position, said electromechanical valve actuator comprising: 
 an armature stem;    a valve stem;    a passage defined by one of said armature stem and said valve stem, said passage including a check ball seat;    an annular sleeve coupled to one of said armature stem and said valve stem; and    a check ball being free to move within said passage when one of said armature stem and said valve stem defining said passage is stationary.    
     
     
         18 . The beginning of stroke damper of  claim 17  wherein one of said armature stem and said valve stem defining said passage further includes a stem plug including said check ball seat.  
     
     
         19 . The beginning of stroke damper of  claim 17  wherein said check ball engages said check ball seat when the valve is moved from a closed to an open position.  
     
     
         20 . The beginning of stroke damper of  claim 17  wherein one of said armature stem and said valve stem defining said passage further includes a stem plug including said check ball seat, said stem plug defining a check ball cavity for retaining said check ball and wherein when the valve is in either the open or closed position said check ball is free to move within the check ball cavity.  
     
     
         21 . The beginning of stroke damper of  claim 17  wherein said check ball engages said check ball seat only when the valve is moved from the closed to the open position.