Abstract:
A low-drag seal arrangement for a thermal management valve including a housing having a chamber and at least one bore for flowing a fluid medium through the at least one bore between a location exterior of the housing and the chamber of the housing. A rotor is configured to rotate within the chamber of the housing relative to the bore. The rotor moves between a closed position where the flow of fluid medium through the at least one bore is blocked, an open position where the fluid medium flows through the at least one bore and an intermediate position where the flow of fluid medium through the at least one bore is partially restricted by the rotor&#39;s position relative to the bore. The low-drag seal arrangement also includes a face seal piston positioned within the at least one bore and configured to move axially within the bore.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to thermal management valves and low-drag sealing arrangements for use in thermal management valves. 
       BACKGROUND OF THE INVENTION 
       [0002]    Rotor valves are known for use in applications where a source of fluid is directed through a housing to one of several destinations. Such valves can be found in thermal management systems for automotive applications including engine cooling, vehicle cabin HVAC systems, emissions system valves, engine intake valves, engine exhaust management valves. A typical rotor valve has a rotor that can be rotated about a longitudinal axis in a chamber of a valve body or housing. When the rotor is rotated to a closed position, the rotor blocks fluid flow through a bore or passage in the housing. One problem with this type of valve is how to establish an effective fluid seal between the surface of the rotor and the valve body, while at the same time avoiding excessive operating torque or the need to have actuators of significant size. A rotor valve arrangement must both prevent fluid from exiting the valve housing when a particular inlet is in the closed position, but must also prevent pressurized fluid from entering the valve housing through a closed opening. Thus the operating conditions at the various interfaces between the rotor and inlets can vary since some of the bores may be pressurized or in a vacuum or at ambient pressures. 
         [0003]    It is therefore desirable to have a new arrangement where the amount of friction between a resilient member of a piston and valve bore is reduced so that the force of the resilient member and actuator is used more efficiently and in some cases can be changed or reduced in size. It is also desirable to provide an improved arrangement where there is a better sealing connection between the seal arrangement and bore so that when the valve is in the closed position, there is no leakage. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention relates to a low-drag seal arrangement for a thermal management valve. The low-drag seal arrangement includes a housing having a chamber and at least one bore for flowing a fluid medium through the bore between a location exterior of the housing and the chamber of the housing. A rotor is configured to rotate within the chamber of the housing relative to the bore. The rotor moves between a closed position where the flow of fluid medium through the bore is blocked and an open position where the fluid medium flows through the bore. There is also an intermediate position where the flow of fluid medium through the bore is partially restricted by the rotor&#39;s position relative to the bore. The low-drag seal arrangement further includes a face seal piston positioned within the bore configured to move axially within the bore. The face seal piston has a portion coated with low friction material that is in selective engagement with the rotor, when the rotor moves to the closed position or the intermediate position. 
         [0005]    Each bore of the low-drag seal arrangement has a circumferential groove formed in a wall of the bore, where the circumferential groove circumscribes a portion of the face seal piston when the face seal piston is positioned within the bore. A quad-seal is located within the circumferential groove for creating a seal between the bore and the face seal piston. The face seal piston slides bi-directionally through the quad-seal and moves within the bore. During movement of the face seal piston, the quad-seal maintains a sealed connection between the bore and the face seal piston. 
         [0006]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0008]      FIG. 1A  is a cross-sectional schematic view of a low drag seal for a thermal management valve in accordance with the present invention, interacting with a rotor; 
           [0009]      FIG. 1B  is an exploded cross-sectional schematic view of a low drag seal for a thermal management valve in accordance with the present invention 
           [0010]      FIG. 1C  is an exploded cross-sectional schematic view of a low drag seal for a thermal management valve; 
           [0011]      FIG. 1D  is an alternate embodiment of the exploded cross-sectional schematic view of a low drag seal for a thermal management valve; 
           [0012]      FIG. 2A  is a cross-sectional plan view of a thermal management valve having two low drag seals positioned in their respective bores; 
           [0013]      FIG. 2B  is an exploded cross-sectional plan view of one of the low drag seals of  FIG. 2A ; 
           [0014]      FIG. 2C  is an exploded cross-sectional plan view of one of the thermal management valves of  FIG. 2A ; 
           [0015]      FIG. 3  is a cross-sectional schematic diagram of an alternate embodiment of the thermal management valve in accordance with the present invention; and 
           [0016]      FIG. 4  is an alternate embodiment of the invention where the quad-seal is connected to the face seal piston. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0017]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
         [0018]    Referring now to  FIG. 2A , a cross-sectional schematic view of a thermal management valve  10  is shown. In the present embodiment of the invention, the thermal management valve  10  is a rotary valve having a housing  12  with at least one bore, in particular, an outlet bore  14 , a first inlet bore  16  and a second inlet bore  18 . The housing  12  defines a chamber  20  wherein a rotor  22  is configured to rotate within the chamber  20  and interact with the outlet bore  14 , first inlet bore  16  and second inlet bore  18 , in order to open and close the first inlet bore  16  and second inlet bore  18  to control the flow of fluid through the thermal management valve  10 . The thermal management valve according to the present invention operates by having fluid flow through the first inlet bore  16  and second inlet bore  18 , through an aperture  23  in the rotor  22  and into the chamber  20 , when the rotor  22  is rotated to the open position. From the chamber  20  the fluid flows through the valve outlet bore  14 . When the rotor  22  is in the closed position fluid is blocked from leaving the first inlet bore  16  and second inlet bore  18  past the rotor  22  into the chamber  20 . It is within the scope of this invention for the valve to operate in the reverse manner, where fluid flows into the thermal management valve  10  through the outlet bore  14  and exits through the first inlet bore  16  and second inlet bore  18 . 
         [0019]    The rotor  22  is rotatably positioned on a shaft  24  that extends through the housing  12  and chamber  20 . The shaft  24  is configured to rotate about a longitudinal axis  26  and is rotatably supported on bearings  28  positioned on the walls of the housing  12 . The shaft  24  of the rotor  22  has an actuation end  30  extending outside of the housing  12  for interacting with an actuator  29  that controls the rotation of the shaft  24  and rotor  27  about an axis  26 . The features of the thermal management valve  10  allow for smaller actuators  29  to be used since the amount of torque needed to rotate the shaft  24  will be lowered. 
         [0020]    The first inlet bore  16  and the second inlet bore  18  have a low-drag seal  32  positioned within each of the first inlet bore  16  and second inlet  18 . The low-drag seal  32  selectively contacts the rotor  22  and creates a sealed connection between the low-drag seal  32  and the rotor  22  when the rotor  22  rotates between a closed position, an open position or an intermediate position allowing the flow of fluid through the respective first inlet bore  16  or second inlet bore  18 . 
         [0021]    Referring now to  FIGS. 2B and 2C , the details of the low-drag seal  32  are shown. In particular, the low-drag seal  32  shown in  FIGS. 2A and 2B  have a face seal piston  34  that is positioned within the respective first inlet bore  16  or second inlet bore  18 . While the embodiments of the invention shown in  FIGS. 3A-3B  depict a first inlet bore  16  and second inlet bore  18 , it is within the scope of this invention for there to be a greater or lesser number of inlet bores that can interact with the rotor  22  and control the flow of fluid through the thermal management valve  10 . It is also within the scope of the invention for the first inlet bore  16  and second inlet bore  18  to be inlet bores where fluid is flowing out of the thermal management valve  10  rather than fluid flowing into the thermal management valve  10  as configured in the embodiment of the invention shown in  FIG. 2A . 
         [0022]    Referring to  FIG. 1B , the face seal piston  34  has a portion  36  coated with a low-friction material in order to minimize the amount of friction generated between the contact area  38  between the face seal piston  34  and rotor  22  as well as a portion  45  coated with low-friction material at the seal contact area  40  between the outer surface of the face seal piston  34  and a quad-seal  37 . In operation the reduced friction in the portion causes an inside edge  39  of the face seal piston  34  to begin forming a tight seal against the rotor  22 , which when creates a tight seal across the portion  36 . 
         [0023]    While the face seal piston  34  is described as being coated, it is also within the scope of this invention for the low-friction material to be solid low friction material formed with or into a surface  37  of the face seal piston  34  as shown in  FIG. 2B . In the embodiments shown in  FIGS. 1, 2A and 2B , the portion  36  of the face seal piston  34  coated with low friction material is the surfaces where the contact area  38  and seal contact area surfaces  40  are located; however, it is within the scope of this invention for the entire surface of the face seal piston  34  to be coated with low friction material. The low friction material can be polytetrafluoroethylene (PTFE). Other examples of possible low-friction materials include, but are not limited to, ceramic, nylon, high density polyethylene (HDPE), graphite or other suitable friction materials having a static friction coefficient generally in the range of 0.2 to 0.6, preferably 0.2 to 0.5 and ideally equal to or less than 0.04. 
         [0024]    The face seal piston  34  had an inner surface  19  that is smooth and does not have any ridges or grooves. This allows fluid to flow through the bore  16 ,  18  without being inhibited or deflected by any features on the inside surface of the face seal piston  34 . 
         [0025]    The quad-seal  37  is positioned within a circumferential groove  42  formed in each of the first inlet bore  16  and second inlet bore  18 . The circumferential groove  42  circumscribes a portion of the face seal piston  34  such that the face seal piston  34  extends through and slides back and forth through the quad-seal  37 . The quad-seal  37  creates a seal between the respective first inlet bore  16  and second inlet bore  18  and the respective face seal piston  34 . The face seal piston slides bi-directionally through the quad-seal  37  in a manner that the quad-seal  37  maintains a sealed connection between the respective first inlet bore  16  and second inlet bore  18  and the face seal piston  34 . The present embodiment of the invention describes the use of a quad-seal  37 ; however, it is within the scope of this invention for the quad-seal  37  to be an o-ring  344  as shown in  FIG. 1D . It is also within the scope of this invention for the quad seal  37  to be a lip seal or other suitable seal member. 
         [0026]    The face seal piston  38  has two points of contact  44  that contact the surface of the face seal piston  34 . The two points of contact  44  provide improved sealing between the quad-seal  37  and face seal piston  34 . In particular the quad seal  37  gets squeezed between the bore  16 ,  18  and the outer diameter surface of the face seal piston  34  when the face seal piston moves axially in the bore  16 ,  18  as shown in  FIG. 1C . The squeezing effect helps to center the face seal piston in the bore  16 ,  18 , particularly when the length to width ratio of the face seal piston  34  is low. Also having two points of contact  44  allows for less material of the quad seal  37  to get squeezed. 
         [0027]    Each first inlet bore  16  and second inlet bore  18  have a spring seat  46  extending into the bore above the face seal piston  34 . Between the spring seat  46  and a top surface  48  of the face seal piston  34  is a resilient member  50 . In the present invention, the resilient member  50  is a spring having a first end in contact with the top surface  48  of the face seal piston  34  and second end in contact with the spring seat  46  of the first inlet bore  16  or second inlet bore  18 . The resilient member is configured to apply force on the face seal  34  in the direction of the rotor  22 . As shown in  FIGS. 1, 2A and 2B , the resilient member  50  applies force in a downward direction as shown in the  FIGS. 1, 2A, 2B . 
         [0028]    The present invention utilizes the quad-seal  37  positioned within the circumferential groove  42  in order to provide a better seal and reduce the amount of friction between the quad-seal  37  and the moving face seal piston  34 . The face seal piston  34 , as described above, has a low friction material coating the seal contact area  40  in order to reduce the amount of friction between the quad-seal  37  and the outer surface of the face seal piston  34 . The combination of using low friction material and a quad-seal having two points of contact  44  reduces the amount of drag or friction between the face seal piston  34  and the quad-seal  37  as the face seal piston  34  moves along a longitudinal axis when contacting the rotor  22 . This reduces the amount of torque necessary to rotate the rotor  22 , thereby reducing the size of the actuator  29  and size of the spring  50  needed to rotate the shaft  24  of the rotor  22 . Additionally, the combination of elements described and the thermal management valve  10  reduces the amount of force that the resilient member  50  must supply in order to force the face seal piston  34  into contact with the rotor  22 , resulting in a more efficient use of the amount of force from the resilient member  50 , by allowing it to apply downward force more effectively without having to use some of the force of the resilient member  50 , to overcome the friction or drag between the face seal piston  34  and the quad-seal  37 . 
         [0029]    The present invention is also a distinct advantage over the traditional wiper seals, where a wiper seal having an acceptable radial sealing performance would have a much greater amount of drag between the seal member and the wall of the bore. In the prior art, the seal member is connected to the moving piston and contacts the bore, which is made of polyphenylene sulfide which results in a greater amount of friction between the seal and the wall of the bore. The increased amount of friction does not allow for efficient use of a resilient member, which must be larger in order to overcome the friction force between the seal and the wall of the bore as well as providing enough force to effectively contact and seal the face seal piston against the rotor. 
         [0030]    Referring now to  FIG. 3 , an alternate embodiment of the low-drag seal arrangement  132  is shown. Like reference numbers have been used to designate similar structures in the embodiment of  FIGS. 2A, 2B, 2C  with the reference numerals differing by  100 . As shown in  FIG. 3 , a face seal piston  134  is shown in contact with a rotor  122 . Face seal piston  134  has a reduced diameter portion  139  that reduces a contact area  141  between the face seal piston  134  and rotor  122 . By reducing the contact area  141  compared to the contact area  38  shown in  FIGS. 2B and 2C , the high pressure area Hp located above the rotor  122  flowing through the bore toward the rotor  122  will focus the high pressure onto the inner diameter of the face seal piston  134  in order to make a more absolute seal between the face seal piston  134  and the rotor  122 , when the face seal piston  134  is in the closed position. 
         [0031]    The embodiments described above all pertain to arrangements where the low-drag seal  32 ,  132  is connected to the housing  12 ; however, it is within the scope of this invention for the low-drag seal  32 ,  132  to be positioned on the rotor  22 ,  122  in order to close a bore formed within the housing  12 . 
         [0032]      FIG. 4  shows an alternate embodiment of the invention showing a low-drag seal arrangement  200  where a face seal piston  234  has a circumferential groove  242  formed on the surface of the face seal piston  234 . Within the circumferential groove  242  is a quad-seal  237  which has two points of contact  244  that contact an inside surface of a bore  218  formed through a housing  212  of the low-drag seal arrangement  200  in accordance the present embodiment of the invention. The inside surface of the bore  218  has a portion  236  adjacent the two points of contact  244  that is either a coating of low friction material or low friction material formed into the material of the bore  218 . An inner surface  219  of the face seal piston  234  is smooth and uniform without any ridges or ledges. 
         [0033]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.