Solenoid operated hydraulic control valve

Abstract

A pressure control valve with a hydraulic system of an automatic transmission for a motor vehicle includes a valve body defining a control chamber, fluid ports communicating with the control chamber, and a valve spool having spaced pressure control lands located in the control chamber, the valve spool urged by a compression spring in an opposite direction from an electromagnetic force developed on the spool when a solenoid is energized. In one embodiment a control land is formed with a pressure feedback orifice that communicates a control port with a feedback chamber. The valve spool can be formed with different sized control lands. The feedback orifice is substantially insensitive to fluid temperature variation.

I claim:  
     
         1 . A solenoid-operated valve assembly for an automatic transmission of a motor vehicle, comprising: 
 a valve body having a control chamber, mutually spaced first, second and third ports communicating with the control chamber;    a valve spool supported for movement along the control chamber, including a shank, a first land adapted to open and close the first port, the first land having a feedback chamber and a feedback orifice connecting the feedback chamber and second port, and a second land located at an opposite end of the shank from the first land and adapted to open and close the third port; and    a spring urging the valve spool to move along the control chamber; and    a solenoid assembly having an armature axially displaceable in response to an electric signal supplied to a coil, the armature urging the valve spool to move along the control chamber.    
     
     
         2 . The valve assembly of  claim 1  further comprising: 
 a source of low pressure; 
 wherein the valve body further includes a scaling orifice connecting the feedback chamber and the source of low pressure.  
 
 
     
     
         3 . The valve assembly of  claim 1  wherein the length of the feedback orifice is relatively short.  
     
     
         4 . The valve assembly of  claim 1  wherein the first land and second land have substantially equal diameters.  
     
     
         5 . The valve assembly of  claim 1  wherein the first land has a larger diameter than the diameter of the second land.  
     
     
         6 . The valve assembly of  claim 1  wherein the first port is adapted for connection to a source of supply pressure, the third port is adapted for connection to a source of low pressure, and the second port is adapted to produce control pressure achieved by balancing supply flow from the first port, vent flow to the third port, and control flow to and from the load.  
     
     
         7 . A solenoid-operated valve assembly for an automatic transmission of a motor vehicle, comprising: 
 a valve body having a control chamber, first, second and third ports spaced mutually along, and communicating with the control chamber;    a valve spool located within the control chamber, including a shank, a first land adapted to open and close the first port &and having a first end and second end, a second land located at a opposite end of the shank and adapted to open and close the third port, the second land having a larger diameter than the diameter of the first land;    a damping orifice facing the first end, communicating the control chamber adjacent the first end and a source of low pressure fluid;    a spring urging the valve spool to move along the control chamber; and    a solenoid assembly having an armature axially displaceable in response to an electric signal supplied to a coil, the armature urging the valve spool to move along the control chamber.    
     
     
         8 . The valve assembly of  claim 7  wherein the first control land includes a control edge located at a radially outer surface of the first land at the second end, and a radial step defining an annular surface extending radially between the shank and control edge, and wherein the feedback passage is directed radially and axially from the bore to the annular surface.  
     
     
         9 . The valve assembly of  claim 7  wherein the first port is adapted for connection to a source of supply pressure, the third port is adapted for connection to a source of low pressure, and the second port is adapted to produce control pressure achieved by balancing supply flow from the first port, vent flow to the third port, and control flow to and from the load.  
     
     
         10 . The valve assembly of  claim 9 , wherein the source of fluid at low pressure is a volume of fluid contained apart from the valve assembly.  
     
     
         11 . The valve assembly of  claim 9 , wherein the source of fluid at low pressure is a volume of fluid contained apart from the valve assembly.  
     
     
         12 . A solenoid-operated valve assembly for an automatic transmission of a motor vehicle, comprising: 
 a valve body having a bore, mutually spaced first, second and third ports communicating with the bore;    a valve spool supported for movement along the bore, including a shank, a first land adapted to open and close the first port and having an axial bore extending partially along the first land from the first end thereof toward the second end, a feedback orifice in the first land communicating the second port and said axial bore in the first land, said feedback orifice being substantially shorter in length and smaller in diameter than said axial bore in the first land;    the first control land including a control edge located at a radially outer surface of the first land at the second end, and a radial step defining an annular surface extending radially between the shank and control edge, and wherein the second feedback orifice extends from the bore to the annular surface;    a spring urging the valve spool o move along the control chamber; and    a solenoid assembly having an armature axially displaceable in response to an electric signal supplied to a coil, the armature urging the valve spool to move along the control chamber.    
     
     
         13 . The valve assembly of  claim 12  further comprising: 
 a source of low pressure;  
 wherein the valve body further includes a scaling orifice connecting the feedback chamber and the source of low pressure.  
 
     
     
         14 . The valve assembly of  claim 12  wherein the first land and second land have substantially equal diameters.  
     
     
         15 . The valve assembly of  claim 12  wherein the first land has a larger diameter than the diameter of the second land.  
     
     
         16 . The valve assembly of  claim 12  wherein the first port is adapted for connection to a source of supply pressure, the third port is adapted for connection to a source of low pressure, and the second port is adapted to produce control pressure achieved by balancing supply flow from the first port, vent flow to the third port, and control flow to and from the load.