Patent Publication Number: US-2023160484-A1

Title: Pressure Control Valve

Description:
BACKGROUND 
     The present application relates to a pressure control valve used in pneumatic braking systems for commercial vehicles. 
     A pressure control valve, also known as a modulator, is used to regulate the air pressure in brake cylinders during an anti-lock braking or similar event. The air pressure to a friction braking device at a wheel end is precisely controlled through solenoids that direct control pressure through passages built into the pressure control valve. The timing required to exhaust the control pressure in the pressure control valve after a vehicle braking event is regulated by law. Traditional pressure control valves have used bias pistons and large cross sectional diameter ports to direct the control pressure to exhaust at the end of the anti-lock braking event. These solutions require multiple components and complicated assemblies. Accordingly, those skilled in the art continue with research and development efforts in the field of pressure control valves to improve the exhaust timing. 
     SUMMARY 
     In accordance with one embodiment, a pressure control valve includes an upper body, a lower body affixed to the upper body, a supply passage in the upper body, a delivery passage in the upper body, an exhaust passage in the lower body and a pivotable member positioned between the supply passage and the delivery passage. The pivotable member has a generally curved body, a first leg, a second leg and a third leg extending from the body. The pivotable member pivots on the second leg and the third leg in response to air pressure in the supply passage being less than the air pressure in the delivery passage. The positioning of the pivotable member restricts air from flowing from the delivery passage to the supply passage, thereby opening a path for the air to pass to the exhaust passage. 
     In accordance with another embodiment, a method of controlling air flow in a brake valve includes passing air through a delivery passage of the brake valve and into contact with a pivotable member disposed on a diaphragm between the delivery passage and the supply passage. A pivotable member pivots in response to a higher air pressure in the delivery passage than the supply passage. Air is then passed through an exhaust passage of the brake valve in response to the pressure differential between the delivery passage and the supply passage. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a representational cross sectional view of a pressure control valve having a pivotable member according to one example of the present invention. 
         FIG.  1 B  is a representational cross sectional view of the valve of  FIG.  1 A  as rotated ninety degrees on the y-axis. 
         FIG.  1 C  is a representational cross sectional view of the valve of  FIG.  1 B  having a support plate. 
         FIG.  2 A  is a representation of the pivotable member prior to installation in the valve of  FIG.  1 A . 
         FIG.  2 B  is an isometric view of the pivotable member of  FIG.  2 A . 
         FIG.  3 A  is a representational cross sectional view of the valve of  FIG.  1 A  as rotated ninety degrees on the x-axis, where the pivotable member is in an exhaust position. 
         FIG.  3 B  is a view of the valve as shown in  FIG.  3 A , where the pivotable member is in an apply position. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG.  1 A , a cross sectional view of a pressure control valve  10  is illustrated. The valve  10  comprises an upper body  26  and a lower body  28 . The upper body  26  and lower body  28  are machined, molded, or cast. The upper body  26  and lower body  28  are held together by fasteners (such as screws), welding, or other means of attachment. The material of the valve  10  can be a metal or a polymer or both. Polymer materials include, but are not limited to, thermoset polymers and thermoplastic polymers. Metals include, but are not limited to, aluminum, steel, and zinc. In one embodiment, the upper body  26  and the lower body  28  are made of aluminum. 
     A supply port  13  and a supply passage  12  for receiving pressurized air are formed in the upper body  26 . A delivery port  15  and a delivery passage  14  for delivering pressurized air to an associated braking device are formed in the upper body  26 . An exhaust port  17  and an exhaust passage  16  for exhausting pressurized air to atmosphere is formed in the lower body  28 . Each of the passages  12 ,  14 ,  16  are in communication with each other at different operating states of the pressure control valve  10 . 
     A diaphragm  22  separates the supply passage  12  from the delivery passage  14  when no pressure is being applied to the supply port  13 . When air pressure is present in the supply passage  12 , the diaphragm  22  moves to allow communication between the delivery passage  14  and the supply passage  12 . 
     A solenoid assembly  18  is assembled into the lower body  28  for controlling the movement of the pressurized air among the supply passage  12 , the delivery passage  14  and the exhaust passage  16 . The solenoid assembly  18  receives an electrical control signal from a control unit (not shown). 
     A pivotable member  30  is disposed longitudinally in the supply passage  12 , when the valve  10  is in the position shown in  FIG.  1 A . One end of the pivotable member  30  rests on the diaphragm  22  that separates the supply passage  12  from the delivery passage  14 . The opposite end of the pivotable member  30  is secured in a cavity  20  formed in the upper body  26 . 
       FIG.  2 A  shows the pivotable member  30  by itself. The pivotable member  30  has a generally curved body  40  having a first leg  32  and a second leg  34 . A third leg  36  is located on an opposite side of the body  40  as the first leg  32  and second leg  34 . The first leg  32  has a length of about 2.7 mm, which is shorter than the length of about 3 mm of the second leg  34 . The overall length L 1  of the pivotable member  30  is about 24 mm. 
     The third leg  36  is wider than the first leg  32  and second leg  34 . As shown in  FIG.  2 A , the third leg  36  has a width of about half of the overall width of the body  40 . The third leg  36  includes a protrusion  37  that assists in the pivoting motion of the pivotable member  30  when inserted in the cavity  20 . The pivotable member  30  pivots on an axis A through the second leg  34  and third leg  36 . The wider shape of the third leg  36  is beneficial because it guides the pivoting motion. 
     An aperture  38  may be located in an approximate central portion of the body  40 . The diameter of the aperture  38  may be changed based on desired timing when the valve  10  is being exhausted. 
     The material of the pivotable member  30  includes, but is not limited to, metal, rubber or plastic or a combination of materials. 
       FIG.  1 B  shows a cross section view of the valve  10 , as rotated ninety degrees on the y-axis from the view in  FIG.  1 A . The pivotable member  30  as shown in  FIG.  2 A  is installed in the supply passage  12  in the upper body  26 . The pivotable member  30  overlays the entire diameter of the supply passage  12 . The aperture  38  is in line with the supply passage  12 . 
     The second leg  34  of the pivotable member  30  rests on the diaphragm  22 . The second leg  34  rests on a location offset by two millimeters or more from a top surface of the diaphragm  22 . This positioning allows for the diaphragm  22  to move axially during operation of the valve  10 . The first leg  32  does not touch the diaphragm  22 . 
     The cavity  20  in the upper body  26  receives the third leg  36 . The cavity  20  is shaped to hold the third leg  36  while still allowing the pivotable member  30  to pivot on the axis A. The axis A is generally parallel to an axis B that runs centrally through the diaphragm  22 . However, the pivotable member  30  may tilt from axis A because it is not secured in place at the second leg  34 . 
     The first leg  32  guides the pivotable member  30  and limits any tilt or inclination during movement to less than about 20° from a plane made by the first leg  32 , the second leg  34  and the third leg  36  in response to the air pressure. Tilt or inclination of up to about 20° does not affect the ability of the pivotable member  30  to seal the supply passage  12 . 
     In another embodiment, as shown in  FIG.  1 C , a support plate  24  also separates the supply passage  12  from the delivery passage  14 . The support plate  24  rests on the diaphragm  22 . The second leg  34  of the pivotable member  30  rests on the support plate  24 , which in turn rests on the diaphragm  22 . The benefit of the support plate  24  is to protect the diaphragm  22  from over-extension throughout the operation of the valve  10 . 
       FIG.  2 B  shows an isometric view of the pivotable member  30  of  FIG.  2 A . The curve of the body  40  is formed to complement the cylindrical shape of the interior wall at the supply passage  12  of the valve  10  to improve the sealing of the supply passage  12  when in the exhaust position. 
     Therefore, a pressure control valve includes an upper body, a lower body affixed to the upper body, a supply passage in the upper body, a delivery passage in the upper body, an exhaust passage in the lower body and a pivotable member positioned between the supply passage and the delivery passage. The pivotable member has a generally curved body, a first leg, a second leg and a third leg extending from the body. The pivotable member pivots on the second leg and the third leg in response to air pressure in the supply passage being less than the air pressure in the delivery passage. The positioning of the pivotable member restricts air from flowing from the delivery passage to the supply passage, thereby opening a path for the air to pass to the exhaust passage. 
       FIG.  3 A  shows a cross sectional view of the valve  10  as in  FIG.  1 A  but rotated ninety degrees on the x-axis. The locations of the supply port  13  and delivery port  15  are shown for orientation purposes. The pivotable member  30  is in an exhaust position, where air is being diverted from the delivery passage  14  to the exhaust passage  16  because the pressure in the delivery passage  14  is greater than the pressure in the supply passage  12 . This state occurs at the end of a braking event. While a majority of air exits through the exhaust passage  16  through the exhaust port  17  to atmosphere, a portion flows back to the supply passage  12 . The pivotable member  30  closes the supply passage  12 , except for a portion of the air that passes through the aperture  38 . Having a portion of air pass through the aperture  38  between the supply passage  12  and the delivery passage  14  is beneficial to exhaust air more quickly from the associated braking device. 
     The aperture  38  is sized to assist in driver feel as the service brakes are released. If a perfect seal existed between the delivery passage  14  and the supply passage  12 , the release of the service brakes would feel more sudden rather than the gradual release as expected by a driver. In addition, if the exhaust passage  16  is blocked, such as by debris or frozen water, the aperture  38  provides another means for pressurized air to exit the valve  10 . 
     In the exhaust position, the time to exhaust air from the delivery passage  14  to the exhaust passage  16  at the end of a braking event is reduced by between about 2% to about 20% from a valve that does not have the inventive pivotable member  30 . 
       FIG.  3 B  shows a view of the valve  10  as in  FIG.  3 A , but now the pivotable member  30  is shown in an apply position. The pivotable member  30  is moved about two to three millimeters laterally from the exhaust position. The air from the supply passage  12  is greater than in the delivery passage  14 , causing the pivotable member  30  to pivot to open a pathway for the pressurized air between the supply passage  12  and the delivery passage  14 . The travel of the pivotable member  30  from the apply position to the exhaust position in one example is from about ten degrees to about twenty five degrees. 
     The first leg  32  is shaped so as to prevent the pivotable member  30  from tilting when moving from the exhaust position to the apply position. No biasing spring or other element is necessary for the pivotable member  30  to move from the apply position to the exhaust position. No machined or welded stop feature inside the valve  10  is required to prevent excess movement of the pivotable member  30 . Therefore, both the location proximate to the supply passage  12  and the novel shape of the pivotable member  30  improves the ability to move from the apply position to the exhaust position and the speed at which air is exhausted the air from the delivery passage  14 . 
     Therefore, a method of controlling air flow in a brake valve includes passing air through a delivery passage of the brake valve and into contact with a pivotable member disposed on a diaphragm between the delivery passage and the supply passage. A pivotable member pivots in response to a higher air pressure in the delivery passage than the supply passage. Air is then passed through an exhaust passage of the brake valve in response to the pressure differential between the delivery passage and the supply passage. 
     While the present invention has been illustrated by the description of example processes and system components, and while the various processes and components have been described in detail, applicant does not intend to restrict or in any way limit the scope of the appended claims to such detail. Additional modifications will also readily appear to those skilled in the art. The invention in its broadest aspects is therefore not limited to the specific details, implementations, or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.