Patent Publication Number: US-2022228580-A1

Title: Valve plate for fluid pump

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a National Stage application of International Patent Application No. PCT/EP2020/025303, filed on Jun. 26, 2020, which claims priority to Indian Application No. 201911025337 filed on Jun. 26, 2019, each of which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to fluid pumps having a rotating group and more particularly to a valve plate for use with such fluid pumps. 
     BACKGROUND 
     Valve plates are used in fluid pumps to provide fluid to expanding pumping chambers in the fluid pump and to provide a path for fluid to be discharged from contracting pumping chambers. While valve plates in fluid pumps have been improved over the years, issues have persisted with regard to noise and damage due to cavitation. 
     SUMMARY 
     An aspect of the present disclosure relates to a valve plate for a fluid pump. The valve plate includes a body having a first surface and an oppositely disposed second surface. The body defines a first kidney slot that extends through the first and second surfaces and a second kidney slot that extends through the first and second surfaces. A first notch is disposed in the first surface of the body and extends outwardly from the first kidney slot in a direction toward the second kidney slot. A second notch is disposed in the first surface and extends outwardly from the first kidney slot in a direction toward the second kidney slot. The second notch is separated from the first notch. 
     Another aspect of the present disclosure relates to a fluid pump. The fluid pump includes a barrel that defines a plurality of cylinder bores and a plurality of fluid passages in fluid communication with the plurality of cylinder bores. A plurality of pistons is disposed in the plurality of cylinder bores. The pistons are adapted to reciprocate in the cylinder bores. A valve plate is in fluid communication with the barrel. The valve plate includes a first kidney slot having a first end and a second end, a second kidney slot having a first end and a second end. The second kidney slot is disposed in the body so that the second end of the second kidney slot is adjacent to the first end of the first kidney slot. A first notch I extends outwardly from the first end of the first kidney slot. A second notch extends outwardly from the first end of the first kidney slot. The first notch is separated from the second notch. A length of the first notch is greater than a length of the second notch. 
     Another aspect of the present disclosure relates to a fluid pump. The fluid pump includes a barrel that defines a plurality of cylinder bores and a plurality of fluid passages in fluid communication with the plurality of cylinder bores. A plurality of pistons is disposed in the plurality of cylinder bores. The pistons are adapted to reciprocate in the cylinder bores. A valve plate is in fluid communication with the barrel. The valve plate includes a first kidney slot in intermittent fluid communication with the plurality of fluid passages and a second kidney slot in intermittent fluid communication with the plurality of fluid passages. A transition land is disposed between the first and second kidney slots. A first notch extends outwardly from the first kidney slot into the transition land. A second notch extends outwardly from the first kidney slot in the transition land. The second notch is separated from the first notch. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a fluid pump having exemplary features of aspects in accordance with the principles of the present disclosure. 
         FIG. 2  is an isometric view of a valve plate suitable for use with the fluid pump of  FIG. 1 . 
         FIG. 3  is a front view of the valve plate of  FIG. 2 . 
         FIG. 4  is a front view of the valve plate showing the interface between a single fluid passage of a barrel of the fluid pump and the valve plate. 
         FIG. 5  is a front view of the valve plate showing the interface between a single fluid passage of a barrel of the fluid pump and the valve plate with the barrel in an advanced rotational position. 
         FIG. 6  is a front view of the valve plate showing the interface between a single fluid passage of a barrel of the fluid pump and the valve plate with the barrel in an advanced rotational position. 
         FIG. 7  is a front view of the valve plate showing the interface between a single fluid passage of a barrel of the fluid pump and the valve plate with the barrel in an advanced rotational position. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the exemplary aspects of the present disclosure that are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like structure. 
     Referring now to  FIG. 1 , a fluid pump  10  is shown. In the depicted embodiment, the fluid pump  10  includes a pump housing  12 , a rotating group  14 , a valve plate  16 , a swashplate  18  and an endcap  20 . 
     The pump housing  12  of the fluid pump  10  defines a pumping chamber  22 . In the depicted embodiment, the rotating group  14  is disposed in the pumping chamber  22 . 
     The rotating group  14  includes a barrel  24  having a first end  26  and an oppositely disposed second end  28 . The barrel  24  defines a plurality of cylinder bores  30  that extend through the first end  26  of the barrel  24 . The barrel  24  further defines a plurality of fluid passages  32  that extend through the second end  28  of the barrel  24  and are in fluid communication with the cylinder bores  30  so that each fluid passage  32  is in fluid communication with a corresponding cylinder bore  30 . 
     The rotating group  14  further includes a plurality of pistons  34 . Each piston  34  includes a first axial end portion  36  and an oppositely disposed second axial end portion  38 . The first axial end portions  36  of the pistons  34  are disposed in the cylinder bores  30 . The second axial end portions  38  of the pistons  34  are disposed in contact with slippers  40 . When an angle of the swashplate  18  is greater than zero, the pistons  34  are adapted to reciprocate in the cylinder bores  30  as the barrel  24  rotates. The slippers  40  slide across a surface of the swashplate  18  as the barrel  24  rotates. 
     In the depicted embodiment, a central bore  42  of the barrel  24  is engaged with an input shaft  44 . In the depicted embodiment, the central bore  42  of the barrel  24  is in splined engagement with the input shaft  44 . In a pumping mode, the rotating group  14  rotates about a central axis  46  in response to rotation of the input shaft  44 . 
     The fluid pump  10  defines a fluid inlet and a fluid outlet (not shown). In the one embodiment, the endcap  20  defines the fluid inlet and outlet. The fluid inlet and outlet are in fluid communication with the cylinder bores  30  of the rotating group  14  through the valve plate  16 , which is stationary in the depicted embodiment. When an angle of the swashplate  18  is greater than zero, fluid enters the expanding cylinder bores  30  from the fluid inlet, through the valve plate  16 , and into the fluid passages  32  corresponding to the expanding cylinder bores  30  in response to rotation of the input shaft  44 . Fluid is discharged from the contracting cylinder bores  30  through the corresponding fluid passages, the valve plate  16  and through the fluid outlet as the input shaft  44  rotates. 
     Referring now to  FIGS. 2 and 3 , the valve plate  16  is shown. The valve plate  16  includes a body  50 . The body  50  includes a first surface  52  and an oppositely disposed second surface  54 . The body  50  defines a central opening  56  that extends through the first and second surfaces  52 ,  54 . The central opening  56  defines a center axis  58 . When the valve plate  16  is disposed in the fluid pump  10 , the center axis  58  of the valve plate  16  is generally aligned with the central axis  46 . 
     The body  50  of the valve plate  16  further defines a first kidney slot  60  and a second kidney slot  62 . The first and second kidney slots  60 ,  62  extend through the first and second surfaces  52 ,  54  of the body  50 . In the depicted embodiment, the first and second kidney slots  60 ,  62  are generally arcuate in shape. 
     The first kidney slot  60  includes a first end  64  and an oppositely dispose second end  66 . The second kidney slot  62  includes a first end  68  and an oppositely disposed second end  70 . The body  50  includes a circumferential reference  71 . The circumferential reference  71  bisects the first and second ends  64 ,  66  of the first kidney slot  60  and the first and second ends  68 ,  70  of the second kidney slot  62  so that the circumferential reference  71  passes through the center of the first and second kidney slots  60 ,  62 . The first and second kidney slots  60 ,  62  are disposed on the circumferential reference  71  about the center axis  58  of the valve plate  16 . 
     The first and second kidney slots  60 ,  62  are generally adjacent to each other. In the depicted embodiment, the first end  64  of the first kidney slot  60  is disposed adjacent the second end  70  of the second kidney slot  62 . 
     The first kidney slot  60  is in fluid communication with one of the fluid inlet and the fluid outlet while the second kidney slot  62  is in fluid communication with the other of the fluid inlet and the fluid outlet. In the preferred embodiment, the first kidney slot  60  is in fluid communication with the fluid outlet while the second kidney slot  62  is in fluid communication with the fluid inlet. 
     In the one embodiment, the first kidney slot  60  includes a plurality of kidney slots. In the depicted embodiment, the first kidney slot  60  includes four kidney slots. 
     As the rotating group  14  rotates in response to rotation of the input shaft  44  when the swashplate  18  is disposed at an angle greater than zero, the fluid passages  32  of the barrel  24  slide across the first surface  52  of the valve plate  16  so that fluid passages  32  are in fluid communication with the first kidney slot  60  as the pistons  34  retract in the cylinder bores  30  and in fluid communication with the second kidney slot  62  as the pistons  34  extend from the cylinder bores  30 . The first kidney slot  60  is separated from the second kidney slot  62  by a transition land  72 . The transition land  72  is disposed at a location on the first surface  52  of the valve plate  16  where the pistons  34  are transitioning between extending and retracting. 
     The body  50  of the valve plate  16  further defines a first notch  74  and a second notch  76 . The first and second notches  74 ,  76  are disposed on the first surface  52  of the valve plate  16  and are in fluid communication with the first kidney slot  60 . The first and second notches  74 ,  76  are configured to reduce noise in the fluid pump  10  and to reduce the likelihood of erosion due to cavitation in the first surface  52  of the valve plate  16 . 
     The first notch  74  extends outwardly from the first kidney slot  60  in a direction toward the second kidney slot  62 . It will be understood that the phrase “toward the second kidney slot  62 ” in reference to the first notch  74  as used herein and in the claims is in a direction such that the first notch  74  overlaps a portion of the fluid passages  32  of the barrel  24  as the barrel  24  rotates and as those fluid passages  32  pass through the transition land  64  thereby establishing intermittent fluid communication between the first notch  74  and the fluid passages  32 . 
     In the depicted embodiment, the first notch  74  extends linearly outwardly from the first kidney slot  60 . In other embodiments, the first notch  74  is arcuate in shape. In the depicted embodiment, the first notch  74  extends outwardly from the first kidney slot  60  by a length LI. In one embodiment, the first notch  74  is a U-shaped notch. In another embodiment, the first notch  74  is a V-shaped notch. The first notch  74  has a width WI. 
     The second notch  76  extends outwardly from the first kidney slot  60  in a direction toward the second kidney slot  62 . In the depicted embodiment, the second notch  76  extends linearly outward from the first kidney slot  60 . In other embodiments, the second notch  76  is arcuate in shape. It will be understood that the phrase “toward the second kidney slot  62 ” in reference to the second notch  76  as used herein and in the claims is in a direction such that the second notch  76  overlaps a portion of the fluid passages  32  of the barrel  24  as the barrel  24  rotates and as those fluid passages  32  pass through the transition land  72  thereby establishing intermittent fluid communication between the second notch  76  and the fluid passages  32 . 
     The second notch  76  extends outwardly from the first kidney slot  60  by a length L 2 . In one embodiment, the second notch  76  is a U-shaped notch. In another embodiment, the second notch  76  is a V-shaped notch. The second notch  76  has a width W 2 . 
     In the depicted embodiment, the length LI of the first notch  74  is greater than the length L 2  of the second notch  76 . In the depicted embodiment, the width WI of the first notch  74  is greater than the width W 2  of the second notch  76 . 
     The second notch  76  is separate and distinct from the first notch  74 . The second notch  76  is separated from the first notch  74  by a portion  78  of the first surface  52  of the valve plate  16  so that the portion  78  of the first surface  52  is disposed between the first and second notches  74 ,  76 . The first and second notches  74 ,  76  extend outwardly from the first kidney slot  60  into the transition land  72 . 
     In the depicted embodiment, the first notch  74  extends outwardly from an outer portion  84  of the first end  64  of the first kidney slot  60 . The second notch  76  extends outwardly from an inner portion  86  of the first end  64  of the first kidney slot  60 . The outer portion  84  of the first end  64  of the first kidney slot  60  is disposed outside of the circumferential radius  71  while the inner portion  86  of the first end  64  of the first kidney slot  60  is disposed inside the circumferential reference  71  so that a distance from the center axis  58  to the outer portion  84  of the first end  64  of the first kidney slot  60  is greater than a distance from the center axis  58  to the inner portion  86  of the first end  64 . 
     Referring now to  FIGS. 1 and 4-6 , the operation of the fluid pump  10  will be described. As previously provided, the input shaft  44  rotates causing the rotating group  14  to rotate. As the rotating group  14  rotates, fluid enters the cylinder bores  30  through the interface between the fluid passages  32  of the barrel  24  and the second kidney slot  62 . Fluid is discharged from the cylinder bores  30  through the interface between the fluid passages  32  of the barrel  24  and the first kidney slot  60 .  FIGS. 4-6  show the interface between one of the plurality of fluid passages  32  and the first and second kidney slots  60 ,  62  as the fluid passage  32  passes through the transition land  72 . 
     Referring now to  FIG. 4 , the fluid passage  32  is shown in fluid communication with the second kidney slot  62 . In  FIG. 5 , the barrel  24  is shown in a position in which the fluid passage  32  is in the transition land  72 . In the transition land  72 , the fluid passage  32  ceases fluid communication with the second kidney slot  62 . As the barrel  24  rotates, a low-pressure area  90  forms in an inner diameter portion of the fluid passage  32 . This low-pressure area  90  is formed in part due to centrifugal forces, which are caused by the rotation of the barrel  24 , acting on the fluid in the fluid passage  32 . High-velocity fluid entering the fluid passage  32  at the interface between the first notch  74  and the fluid passage  32  also contributes to the low-pressure area  90 . The centrifugal forces redistribute the fluid toward the outer diameter portion of the fluid passage  32  causing the pressure of the fluid at the inner diameter portion of the fluid passage  32  to drop. When the pressure of the fluid in the low-pressure area  90  drops below the vapor pressure of the fluid, vapor bubbles are formed in the fluid. 
     In the position shown in  FIG. 6 , the outer diameter portion of the fluid passage  32  is in fluid communication with the first notch  74 . This fluid communication between the first notch  74  and the fluid passage  32  is adapted to provide a controlled rise rate in the pressure of the fluid in the fluid passage  32 . This controlled rise rate in pressure in the fluid passage  32  reduces noise in the fluid pump I 0 . 
     Referring now to  FIG. 7 , as the fluid passage  32  continues passing through the transition land  72 , the inner diameter portion of the fluid passage  32  comes into fluid communication with the second notch  76  while the outer diameter portion of the fluid passage  32  maintains fluid communication with the first notch  74 . In one embodiment, the length L 2  of the second notch  76  is less than the length LI of the first notch  74 . In one embodiment, the fluid passage  32  doesn&#39;t begin fluid communication with the second notch  76  until the piston  34  starts to retract in the bore  30 . The retraction of the piston  34  in the bore  30  and the controlled introduction of fluid into the fluid passage  32  through the second notch  76  gradually increases the fluid pressure in the low-pressure area  90  of the fluid passage  32 . This gradual increase in fluid collapses the vapor bubbles at a reduced collapse rate, which reduces the likelihood of erosion on the first surface  52  of the valve plate  16 . 
     Various modifications and alterations of this disclosure will become apparent to those skilled in the art without departing from the scope and spirit of this disclosure, and it should be understood that the scope of this disclosure is not to be unduly limited to the illustrative embodiments set forth herein.