Abstract:
Particularly in an engine that has been inactive for a substantial period of time at a cold temperature, fluid forces acting on moving members, such as electronically-activated fluid control valves, may be significant until the engine warms up. A way to reduce the fluid forces and their detrimental effects is to reduce the volume of fluid which are creating the fluid forces, including venting all or some of this fluid to drain. Additionally, fluid that gathers can be drained away. In order to accomplish such venting, the present disclosure includes a fluid control valve having a body with at least one fluid passage connected to a bore, a movable member in the bore, an actuator connected to the movable member to move the movable member, and at least one vent passage opening into the bore between the fluid passage and the actuator. The disclosure may include additional drain passages to drain away gathered fluid from actuating components.

Description:
TECHNICAL FIELD  
       [0001]     The present disclosure relates to a fluid control valve and more particularly an apparatus and method for reducing fluid forces acting on a fluid control valve.  
       BACKGROUND  
       [0002]     Fluid control valves are well known in the art to provide on/off control of fluid flow, through the use of electrical control signals. Such fluid control valves may find use in internal combustion engines, in fuel systems, and/or in systems that control motion of the engine valves, such as a compression release braking system, or a system in which typical camshaft-produced valve events are modified by way of fluid action. In some cases such fluid control valves may be inactive for a substantial period of time at a cold temperature. These fluid control valves may be prone to slow opening and closing until such time that the fluid viscosity changes due to temperature change as the engine warms up, or the local fluid viscosity changes due to shearing effects of fluid as the fluid control valve is repeatedly operated, or a combination of these and/or other changes.  
         [0003]     Such problems are believed to be caused by fluid collecting in undesired regions where it can fully or partially restrict motion of the moving members of the fluid control valve, or by fluid that finds its way into the clearance spaces that exist between stationary and movable members of the fluid control valves.  
         [0004]     U.S. Pat. No. 5,478,045 discloses draining damping fluid with respect to one cavity of an actuator chamber of a fluid control valve, but is silent regarding fluid in other locations of the device.  
         [0005]     The present disclosure is directed to overcoming one or more of the deficiencies as set forth above.  
       SUMMARY OF THE INVENTION  
       [0006]     In one aspect of the present disclosure, a fluid control valve has a body with at least one fluid passage, an axial bore, a movable member disposed in the bore, an actuator operatively connected to the movable member and adapted to move the movable member in the axial bore, and the body has at least one vent passage opening into the axial bore at an axial location relative to the axial bore between the fluid passage and the actuator, and the vent passage is adapted to vent leakage fluid.  
         [0007]     In another aspect of the present disclosure, a method of reducing fluid forces acting on a movable member movable relative to a body, consisting of moving the movable member in the body with an actuator, and venting leakage fluid from a location between the actuator and a fluid passage. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]      FIG. 1 . is a schematic view of an engine utilizing fluid control valve modification of valve events,  
         [0009]      FIG. 2 . is a diagrammatic cross-sectional view through one embodiment of a fluid control valve,  
         [0010]      FIG. 3  and  FIG. 3   b . are a diagrammatic cross-sectional views through another embodiment of a fluid control valve, and  
         [0011]      FIG. 4 . is a diagrammatic cross-sectional view through yet another embodiment of a fluid control valve. 
     
    
     DETAILED DESCRIPTION  
       [0012]     Referring to the drawings,  FIG. 1  shows an internal combustion engine  10 , having an engine valve  50  movable between closed and open positions relative to a valve seat (all not shown) by a rocker arm  120 . The rocker arm  120  pivots about a center (not shown) in response to movement of a camshaft  40 . Additional components not shown may make up the engine, such as push rods, camshaft followers, lash adjustment mechanism, cylinder head, and the like.  
         [0013]     A valve position modification system  15  has a fluid control valve  20  and a fluidically driven actuator  30 . The valve position modification system may control the opening and closing times of the engine valve  50 .  
         [0014]     The valve position modification system  15  further has a sump  60  connected to a fluid supply  70 , which connects via a first conduit  80  to the fluid control valve  20  and via a second conduit  90  to a check valve  100 . Both the fluid control valve  20  and the check valve  100  connect via a third conduit  110  to the fluidically driven actuator  30 . The fluidically driven actuator  30  is movable to engage the rocker arm  120 . The camshaft  40  is also engages with the rocker arm  120 . The rocker arm  120  is engagable with the engine valve  50  or a valve bridge (not shown). A valve spring  130  may be positioned to bias the engine valve  50  into a closed position.  
         [0015]     Referring now to  FIG. 2 , the fluid control valve  20  has a body  140  with a first fluid passage  150  that intersects an axial bore  160 . A first annular portion  170  may be present in the body  140  or on a movable member  180 , in fluid communication with first fluid passage  150 . In the axial bore  160  is a movable member  180 , which has a valve element portion  190  capable of permitting and blocking fluid flow. The movable member has an axis (not shown) along which linear or axial movement is permitted. A clearance  200  of predetermined magnitude exists between the axial bore  160  and the movable member  180 . The valve element portion  190  may be configured to be either a 2-way or 3-way valve, as are well known in the art. Furthermore, valve element portion  190  may be a poppet-type valve or a spool-type valve, or a combination of these types, as are well known in the art. The embodiment of valve element portion  190  shown in  FIG. 2  permits flow in a first position, and blocks flow in a second position. In the first position, a groove  210  disposed on the movable member  180  is operatively positioned to provide fluid communication between the first fluid passage  150  and a second fluid passage  220 . In the second position, the groove  210  disposed on movable member  180  is operatively positioned to block fluid communication between the first fluid passage  150  and the second fluid passage  220 .  
         [0016]     The second fluid passage  220  intersects the axial bore  160 . A second annular portion  230  may be present in the body  140  or on the movable member  180 , in fluid communication with the second fluid passage  220 .  
         [0017]     The fluid control valve includes a means  238  for reducing fluid forces in a fluid control valve. The means may include a vent passage  240 , which passes through the body  140  and opens into the axial bore  160  at an axial location relative to the axial bore  160  between the first fluid passage  150  and an actuator  250 . The vent passage  240  is adapted to vent leakage fluid and reduce fluid forces acting on the movable member  180 . The vent passage  240  may communicate with the axial bore  160  at a third annular portion  260 , which may be contained in the body  140 , or a fourth annular portion  270  contained in the movable member  180 , or both. The vent passage  240  may be a singular vent passage, or may be a plurality of vent passages.  
         [0018]     An actuator cavity  280  of the fluid control valve  20  adjoins a body end face  290 . The actuator cavity  280  is partially formed by a spacer  300  which adjoins a portion of the body end face  290 , and the actuator  250  which adjoins the spacer  300 . Inside the actuator cavity  280  may be an armature  310 , which is connected to movable member  180 , or which may be formed as an integral portion of movable member  180 . The actuator  250  is operatively connected to the movable member  180  and is adapted to move the movable member  180  in the axial bore  160  to the second position. The actuator  250  may be of either an electromagnetic device or piezo-electric device, as both types are well known in the art. A cap  320  may adjoin the actuator  250 . The cap  320  may be integrally formed with the actuator. A fastener  330  may secure the armature  310  to the movable member  180 . A spring  340  may engage the cap  320  and the fastener  330 , to bias the fastener  330 , the armature  310 , and the movable member  180  to the first position. Other arrangements are possible in which the spring  340  engages the armature  310  or the movable member  180 , rather than engages the fastener  330 .  
         [0019]     The actuator cavity  280  may be drained of fluid through a slot  350  or a passage  360 . The spacer  300  surrounds the armature  310 , and may have one or more slots  350 , in either a first face  370  of the spacer  300  nearer to the body end face  290  or a second face  380  nearer to the actuator  250 , or may have one or more passages  360  passing through the spacer  300 . The passage  360  may be formed by a variety of known methods such as drilling, forming, stamping, electrical discharge machining, laser drilling, or other methods and may optionally include an orifice  390  of smaller diameter or area than the passage  360 .  
         [0020]     Now referring to  FIG. 3   a , the means  238  for reducing fluid forces may also include an inclined drain passage  400  formed in the body  140  at the body end face  290  adjoining the actuator  250 . The inclined drain passage  400  may be arranged substantially radially relative to a centerline of axial bore  160 . As seen in  FIG. 4  in another embodiment, the means  238  for reducing fluid forces may also include the parallel drain passage  410  arranged substantially parallel with respect to the body end face  290 . Each fluid control valve  20  may include a plurality of inclined drain passages  400 , a plurality of parallel drain passages  410 , or a combination of single or plural inclined drain passages  400  and single or plural parallel drain passages  410 .  
         [0021]     Now referring to  FIG. 3   b , the inclined drain passage  400 , and/or parallel drain passage  410  may be arranged to have passage walls  420  that are substantial parallel, or substantial divergent, or may be a combination of passages  400 ,  410  having at least one drain passage  400 ,  410  with passage walls  420  that are substantially parallel and at least one drain passage  400 ,  410  having passage walls  420  substantially divergent. Substantially parallel walls  420  may be advantageous for high volume manufacturing, however, in some cases substantially divergent walls  420  may better drain the actuator cavity  280  than parallel walls  420 .  
       INDUSTRIAL APPLICABILITY  
       [0022]     In operation and with reference to  FIGS. 1 . and  2 ., fluid from the sump  60  is delivered by the fluid supply  70  thorough the conduit  80  and the fluid control valve  20  and through the conduit  90  and the check valve  100  to the conduit  110 , where fluid is delivered to the fluidically driven actuator  30 . The camshaft  40  rotates to move the rocker arm  120  and open the engine valve  50  in a well-known manner. The fluidically driven actuator  30  moves to follow the motion of the rocker arm  120 , and may or may not remain engaged with the rocker arm  120 . A first signal is delivered to the fluid control valve  20 , which moves the movable member  180  to the second position, thereby blocking fluid flow through the fluid control valve  20 . As the camshaft  40  continues to rotate, the rocker arm  120  and the valve  50  begins to return to the closed position, until the rocker arm  120  engages the fluidically driven actuator  20 , which then holds the engine valve  50  in a partially-open position, as fluid flow from the fluidically driven actuator  30  is blocked. A second signal is delivered to the fluid control valve  20 , which moves the movable member  180  to the first position, thereby permitting fluid flow through the fluid control valve  20 , and fluid flow from the fluidically driven actuator  30 . The fluidically driven actuator  30  moves to permit the rocker arm  120  to move so that engine valve  50  can close. The first signal and the second signal could be analog or digital signals and could be the presence of a signal or the absence of a signal.  
         [0023]     In particular, when the second signal is delivered, the actuator  250  is de-energized, and spring  340  holds the movable member  180  in the first position to permit fluid to flow between the first fluid passage  150  and the second fluid passage  220 . At the first position, fluid flows from the fluidically driven actuator  30  and no modification of the valve events occurs. The valve spring  130  pushes fluid out of the fluidically driven actuator  30 , through the fluid control valve  20 , into the fluid supply  70 .  
         [0024]     When the first signal is delivered, the actuator  250  is energized, and the force of spring  340  is overcome, and the movable member  180  responsively moves linearly or axially along its axis to the second position to block fluid flow between the first fluid passage  150  and the second fluid passage  220 . At the second position, the valve element portion  190  blocks flow of fluid from the fluidically driven actuator  30  and a modification of the valve closing timing occurs.  
         [0025]     To improve the operation of the flow control valve  20  when fluid travels along the clearance  200  between the axial bore  160  and the movable member  180 , venting of fluid to the outside of the fluid control valve  20  occurs, through the vent passage  240 , before fluid reaches the actuator cavity  280 . Such venting reduces the amount of fluid present in the clearance  200  that can slow the opening or closing of the movable member  180 . Communication of fluid from the clearance  200  to the vent passage  240  may be enhanced by the presence of a first annular portion  170  on body  140  or a second annular portion  230  on movable member  180 , which collects fluid from the entire clearance  200  around the movable member  180 , rather than only at the intersection of the vent passage  240  and the axial bore  160 .  
         [0026]     In the event that fluid does reach the actuator cavity  280 , the slot  350  or the passage  360  and the one or more drain passages  400 ,  410  reduce the amount of fluid collected in the actuator cavity  280  that may slow the opening or closing of the movable member  180 . Operation of the fluid control valve  20  under hot conditions for a period of time is more likely to cause low viscosity fluid to reach the actuator cavity  280 , that drains out through the aforementioned slots  350  and/or passages  360 , rather than collecting, as collected fluid has a tendency to slow the opening or closing of the movable member  180 . Should collected fluid in actuator cavity  280  or fluid in the clearance  200  cool to a lower temperature during shutdown of the engine  10  for a period of time, the fluid becomes more viscous, requiring larger forces to move the movable member  180  when the operation of the engine  10  is resumed for a later period of time.  
         [0027]     In operation, this disclosure provides a method of reducing the effect of fluid forces acting on a movable member  180  movable relative to a body  140 . The movable member  180  in the body  140  is periodically moved linearly or axially by an actuator  250 , and a continuous venting of leakage fluid occurs from a location in the body  140  between the actuator  250  and a fluid passage  150 . This venting reduces the effect of fluid forces that may be present. Operation is also enhanced when a change in operating temperature occurs, such as when the engine  10  and valve position modification system  15  has been operated repeatedly to move a movable member  180  when fluid is at a first temperature, then stopping operation of the engine  10  and valve position modification system  15 , which discontinues moving of movable member  180 , until a later time when fluid is at a second temperature is less than first temperature. By venting some fluid during warm operation, a lesser amount of fluid remains which can restrict motion of the movable member during cooler operation, when the detrimental effect of the fluid is increased due to an increase in fluid viscosity at lower temperatures. Furthermore, the efficiency of collection of fluid increases when venting leakage fluid includes an annular portion  260 , 270  as the fluid is collected from the entire circumference of the movable member  180 . Fluid reaching the actuator cavity  280  is drained near an end face through one or more drain passages  400 ,  410 .  
         [0028]     It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Those skilled in the art will appreciate that other aspects, and features of the present disclosure can be obtained from a study of the drawings, the disclosure, and the appended claims.