Abstract:
A solenoid operated three port pressure control valve assembly of the exhaust pressure bleed type. The valve for the inlet pressure supply port includes a pressure responsive diaphragm with the supply port obturator attached. A bleed orifice in the diaphragm provides viscous dampening of the movement of the obturator and minimizes inlet valve flutter. The valve assembly is disclosed in both normally open and normally closed configurations.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to solenoid operated valves of the type having a supply or inlet port and a pressure control outlet port and an exhaust port through which fluid is discharged to a sump or pressure source return. Such valves are employed to provide electrical control of a fluid pressure signal by controlling the flow of fluid from the inlet port to a valving chamber communicating with the pressure control port and also controlling the amount of fluid bleed to the exhaust for maintaining the desired pressure at the pressure signal outlet port. 
     Solenoid valves of the aforesaid type have found widespread usage in controlling the flow of hydraulic fluid in automatic transmissions for motor vehicles. In such transmissions the shifting of the transmission speed ratios is controlled by an electronic controller providing an electrical signal to the solenoid operated valve which provides a fluid pressure signal to a pressure responsive actuator for effecting the transmission speed ratio change. 
     Known valves employed in automatic transmission shift control have utilized a ball valve member disposed in the valving chamber with the ball moved with respect to a valve seat by an operating rod connected to the solenoid armature for controlling flow from the supply port to the valving chamber. However, valves of this type have encountered instability and flutter of the ball valve member upon exposure to hydraulic transients in the system and vibration encountered by the transmission. Efforts to counteract such instability and valve flutter in solenoid operation transmission shift control valves have utilized stiffer bias springs acting against the ball valve. This results in greater force and increased power requirements for the solenoid. For applications requiring a plurality of shift control valves a prohibitively high power consumption for the valves is the result. 
     The aforesaid solenoid valves employing a ball valve member have been found particularly susceptible to flutter when the ball valve member is in a position to substantially restrict the flow or near the closed position where the flow velocity is increased over the valve seat. It therefore has long been desired to provide a simple and relatively low cost way or means of reducing or eliminating the flutter in a solenoid operated pressure control valve and particularly valves of the type employing solenoid operating off of low voltage power supply widely employed in motor vehicle applications. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a solenoid operated pressure control valve having a supply inlet port valved by a raised surface on a pressure responsive member such as a diaphragm, which raised surface forms an obturator moveable with respect to a valve seat. The obturator is contacted by an operating member extending through an exhaust port valve seat in the valving chamber and the operating member is operatively moved by the solenoid armature. The pressure responsive member preferably in the form of an elastomeric diaphragm has the obturator preferably formed by a rigid insert in the central region of the diaphragm. A bleed orifice provides limited flow across the pressure responsive member to provide viscous dampening of the movement of the obturator. Viscous dampening of the movement of the pressure responsive member and obturator render the valve substantially insensitive to instability and flutter when the valve supply port is subject to transients the valve body is subjected to vibration or the valve is in the nearly closed condition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-section of the valve assembly of the present invention; 
     FIG. 2 is an enlarged view of the lower portion of the body of the assembly of FIG. 1; 
     FIG. 3 is an axonometric view of the pressure responsive member of the assembly of FIG. 1; 
     FIG. 4 is a view similar to FIG. 3 with a portion broken away showing the bleed orifice; 
     FIG. 5 is a view similar to FIG. 1 of an alternate embodiment of the invention with the inlet valve normally open in the de-energized condition; and, 
     FIG. 6 is a view of the valve of FIG. 5 in the energized closed condition. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 and 2, the valve assembly of the present invention is indicated generally at  10  and includes a valve body  12  having a supply or inlet preferably comprising a plurality of circumferentially spaced ports  14  which communicate with a valving chamber  16  formed in the lower end of the body and which is closed by a closure member  18  attached to the body by any suitable expedient, as for example, press fit staking or weldment. 
     The valving chamber  16  communicates with a valving passage  20 , the lower end of which defines a valve seat  22  and the upper end of passage  20  communicates with an enlarged diameter bore  24  which has pressure control outlet ports  26  communicating therewith. 
     The upper end of enlarged bore  24  communicates with an exhaust chamber  28  which has exhaust ports  30  formed therein for discharge to a sump or the source or supply return. The pressure control outlet ports  26  are isolated from the exhaust ports  30  and the inlet supply ports  14  by a pair of resilient seal rings  32 ,  34  disposed in spaced relationship on opposite sides of the pressure control ports  26  in annular grooves  36 ,  38  formed in the outer surface of the body  12 . 
     A pressure responsive member preferably in the form of an elastomeric diaphragm  40  is disposed in the valving chamber  16  and sealed and retained therein by closure member  18  contacting the undersurface of the periphery of the diaphragm  40 . 
     Referring to FIGS. 2 through 4, the diaphragm  40  has a raised surface  42  on the upper side thereof and preferably centrally located, which surface  42  forms a moveable obturator for contacting inlet valve seat  22 . In the presently preferred practice of the invention, as shown in FIGS. 3 and 4, the obturator  42  is formed on a rigid insert  44  disposed in the central region of the diaphragm  40  and which has a small aperture or bleed orifice  46  formed therein. In the presently preferred practice of the invention, the insert  44  may be formed of plastic or metal as required for withstanding the pressure forces to be encountered in its intended application. 
     A bias spring  48  is disposed in valving chamber  16  with the lower end thereof registered against the inside surface of closure  18  and the upper end thereof registered against the undersurface of the insert  44  for biasing the obturator  42  in a direction so as to contact and close against inlet valve seat  22  thereby forming a normally closed valve assembly. 
     Referring to FIG. 1, a solenoid operator indicated generally at  50  has a coil bobbin  52  with coil  54  wound thereon received over a flux ring or collector  56  attached to the upper end of body  12 , with the lower end of bobbin  52  received thereover and registered thereagainst. An upper flux collector or ring  58  is partially received within the upper end of bobbin  52 ; and, the flux rings  56 ,  58  and bobbin  52  are retained on body  12  as an assembly by an outer casing  60  having radially inwardly extending end flanges  61 ,  63 . 
     A moveable armature  62  is slidably disposed within the upper flux collector  58  and has the lower end thereof defining a working air gap with the upper end of the lower flux collector  56 . 
     An operating member or rod  64  is received through armature  62  and secured thereto for movement therewith, with the upper end of rod  64  slidably received in a bearing  66 ; and, the rod  64  extends downwardly through sliding bearing  68  disposed in lower flux collector  56 . Rod  64  extends downwardly into exhaust chamber  28  and into enlarged bore  24 . The lower end of rod  64  has a reduced diameter pin portion  70  formed thereon which extends downwardly through valving passage  20  with the end thereof disposed for contacting obturator  42 . 
     The portion of operating member or rod  64  extending into the exhaust chamber  28  has formed thereon an annular flange  72  which has the undersurface  73  thereof configured to act as a poppet for seating against an annular exhaust valving surface  74  formed at the upper end of the enlarged bore  24 . 
     In operation, the normally closed valve  10  has the obturator  44  seated against valve seat  22  with the solenoid operator  50  de-energized; and, the pin  70  is in contact with the obturator  42  such that surface  73  of poppet  72  is raised from valve seat  74  permitting the pressure control outlet ports  26  to be open to the exhaust ports  30  and thus no pressure signal provided at ports  26 . Upon energization of the solenoid operator  50 , the arrangement of flux ring  58  and  56  is such that lower flux ring  56  acts as a pole piece attracting the armature  62 ; and, armature  62  is moved downwardly by overcoming the bias force of spring  48  tending to close the air gap between the lower surface of armature  62  and the upper end of lower flux ring  56  such that pin  70  progressively moves obturator  42  away from seat  22  and moves poppet  72  closer to valve seat  74  reducing flow to the exhaust and thereby increasing the pressure to the pressure control outlet ports  26 . When the undersurface  73  of poppet  72  contacts valving seating surface  74  and closes the exhaust ports  30  from the pressure control ports  26 , obturator  42  is held away from seat  22  permitting full supply pressure to be applied to the signal control outlet port  26 . 
     The bleed orifice  46  permits a small amount of flow therethrough from opposite sides of the diaphragm  40  as the diaphragm is moved. This viscous flow enables the diaphragm to absorb transients thereagainst as may enter the supply ports  14  and provides dampening of the movement of the obturator  42 . 
     Referring to FIGS. 5 and 6, an alternate embodiment of the valve assembly of the present invention is indicated generally at  80  and is shown in FIG. 5 in the de-energized normally open condition; and, the assembly  80  is shown in FIG. 6 in the energized condition with the inlet closed. 
     The assembly  80  is similar to the assembly  10  of FIGS. 1 through 4 with the exception that the annular armature  82  with operating rod  84  received therethrough and secured for movement therewith has the upper end of a spring  86  registered against the upper bearing  88  with the lower end of the spring  86  registered against the upper end of armature  82  and biasing the armature and operating rod  84  in a downward direction. 
     As in the case of the embodiment  10  of FIGS. 1 through 4, the embodiment  80  of FIGS. 5 and 6 has the operating rod  84  provided with an annular valving surface  90  for closing against the exhaust valve seat  92  for controlling flow to the exhaust port  94 . The lower end of rod  84  has a pin  98  provided thereon for extending downwardly through passage  100  which has a valve seat  102  formed on the undersurface thereof against which is moved an obturator  104  for closing against valve seat  102 . The obturator is attached to a pressure responsive diaphragm  106  which is similar to the diaphragm  40  of FIGS. 3 and 4. The obturator  104  thus controls flow between the supply pressure inlet ports  108  and the passage  100  which communicates with the control pressure signal outlet ports  94 . 
     A relatively light or low rate spring  110  biases the obturator and diaphragm upwardly in a direction to maintain contact with the end of pin  98 . 
     As shown in FIG. 5, with the coil  112  de-energized spring  86  provides sufficient preload to overcome the force of spring  110  and causes the pin  98  to move obturator  104  away from the valve seat  102 . 
     Referring to FIG. 6, the valve is shown with coil  112  energized wherein upper flux ring  114  acts as a pole piece attracting armature  82 ; and, armature  82  is moved upward overcoming the preload force of spring  86  and raises the valving surface  90  from valve seat  92  and allows flow from the pressure control ports  94  to the exhaust ports  93  and moves obturator  104  toward valve seat  102  to restrict flow from the inlet ports  108  through passage  100 . When the coil  112  is fully energized pin  98  is lifted sufficiently to allow obturator  104  to be biased against the valve seat  102  by spring  110  thereby closing flow from inlet  108  through passage  100 . With the inlet valve seat  102  closed, pressure in pressure control ports  94  is bled through the exhaust ports  93  until there is no control signal outlet pressure. 
     It will be understood that a bleed orifice  107  is provided in diaphragm  106 , similar to orifice  46  in diaphragm  40  of FIGS. 3 and 4; and, orifice  107  functions to provide viscous dampening of the movement of the obturator thereby minimizing inlet valve flutter. 
     The present invention thus provides a simple and low cost valve construction employing a pressure responsive diaphragm with a bleed orifice therethrough having the inlet valve obturator moveable therewith and thus the bleed orifice is operative to dampen movement of the obturator. 
     Although the invention has hereinabove been described with respect to the illustrated embodiments, it will be understood that the invention is capable of modification and variation and is limited only by the following claims.