Patent Publication Number: US-2012036993-A1

Title: Compressor valve arrangement

Description:
BACKGROUND OF THE INVENTION 
     The subject matter disclosed herein relates to a compressor and in particular to a piston compressor having a skewed or offset valve arrangement. 
     Compressors, such as a reciprocating or piston compressor  200  for example, typically have a crankcase  202  with a cylinder  204  housing a piston as shown in  FIG. 1 . The piston is coupled to a motor that moves the piston within the cylinder to draw in and compress a gas. A valve plate  206  with a suction port  208  and a discharge port  210  is arranged over one end of the cylinder  204 . Each port  208 ,  210  includes a valve, such as suction valve  212  for example, that is arranged to be normally closed and only opens when the differential pressure across the valve, in the direction of opening, exceeds a level sufficient to overcome valve stiffness and other forces. During operation, the suction valve  212  opens into the cylinder  204  as the piston moves away from the valve plate  206 . This draws a gas, such as air for example, from a suction plenum into the cylinder  204 . When the piston reverses its motion, moving toward the valve plate  206 , the gas in the cylinder  204  is compressed and the suction valve  212  closes. Once the cylinder pressure has surpassed the discharge pressure by a sufficient differential, a discharge valve opens, transferring the compressed gas to a discharge plenum. 
     It is desirable to size the suction valve  212  and discharge valve to maximize the performance of the compressor  200 . However, the size of the valve needs to be offset against other constraints. For example, a wall or bulkhead  214  separates the suction plenum from the discharge plenum. The bulkhead needs to be of sufficient size to withstand the differential pressure between the plenums and also provide support for the valve plate  206 . This reduces the available area for the valves and valve ports  208 ,  210  without interfering with one or more other components. For example, it is desirable to have the suction valve  212  placed on the diametral axis  216  of the cylinder to provide symmetric support for the ends of the valve  212 . To avoid covering the discharge port  210  with the suction valve  212 , the discharge port  210  is moved off the diametral axis  216  as shown in  FIG. 2 . This decreases the space available for the discharge port  210  resulting in a port size that is less than desirable for efficient operation of the compressor  200 . 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to one aspect of the invention, a compressor is provided. The compressor includes a cylinder having a diametral axis. A valve plate covers the cylinder, the valve plate having a suction port positioned on the diametral axis and a discharge port. A valve is arranged having a first end coupled to valve plate and a second end movable between a first position in contact with the suction port and a second position, wherein the valve is arranged on an angle relative to the diametral axis. 
     According to another aspect of the invention, another compressor is provided. The compressor includes a cylinder having a diametral axis. A valve plate is arranged having a suction port positioned on the diametral axis and a discharge port. A valve is arranged having a body with a first end coupled to the valve plate and a second end arranged adjacent the suction port, wherein the valve is arranged on an angle to the diametral axis. 
     According to yet another aspect of the invention, a piston compressor is provided having a suction plenum and a discharge plenum. The compressor includes a cylinder having a diametral axis. A valve plate is arranged having a suction port in fluid communication with the suction plenum. The valve plate further includes a discharge port in fluid communication with the discharge plenum, wherein the suction port is positioned on the diametral axis. A valve having a body is arranged on an angle to the diametral axis, the valve body having a first portion coupled between the crankcase and the valve plate. 
     These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a bottom plan view illustration of a prior art valve plate and cylinder bore in a compressor; 
         FIG. 2  is a bottom plan view illustration of another prior art valve plate having an offset discharge port; 
         FIG. 3  is a bottom plan view illustration of a valve plate and cylinder bore in a compressor in accordance with an exemplary embodiment of the invention; 
         FIG. 4  is a side plan view illustration, partially in section, of the compressor of  FIG. 1 ; 
         FIG. 5  is a side plan view illustration of a portion of the compressor of  FIG. 1 ; 
         FIG. 6  is another side plan view illustration, partially in section, of the compressor of  FIG. 1 ; 
         FIG. 7  is a bottom plan view illustration in accordance with another embodiment of the present invention; and, 
         FIG. 8  is a bottom plan view illustration in accordance with another embodiment of the present invention. 
     
    
    
     The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     A compressor is a device used in a wide variety of applications to provide a pressurized gas. An exemplary embodiment compressor  20  is shown in  FIGS. 3-6 . The compressor includes a crankcase  22  having a cylinder  24 . A piston  26  is arranged within the cylinder  24  and is coupled to a drive (not shown), such as a motor for example. Typically, the compressor  20  may also include other components (not shown), such as a connecting rod and a crankshaft for example, to connect the piston  26  to the motor. The compressor may further include fluid or gas control devices (not shown), such as regulators and valves for example. As will be discussed in more detail herein, the movement of the piston  26  within the cylinder  24  causes the compression and flow of the desired gas. The piston  26  will have one or more components (not shown), such as rings or seals for example, that minimizes or prevents the leakage of compressed gas around the piston  26 . 
     Arranged along one end of the crankcase  22  covering the cylinder  24  is a valve plate  28 . The valve plate  28  is typically coupled to the crankcase  22  by a plurality of bolts (not shown). The valve plate  28  includes a first surface  29  and a second surface  31  that are substantially parallel. A suction port  32  and a discharge port  34  extend through the surfaces  29 ,  31  to provide fluid communication to and from the cylinder  24 . In the exemplary embodiment, the suction port  32  is a substantially cylindrical opening having a center axis  39 . Similarly, the discharge port  34  is a substantially cylindrical opening having a center axis  43 . It should be appreciated that while the cylindrical configuration of ports  32 ,  34  is advantageous for manufacturing and cost reasons, the ports  32 ,  34  may also be configured as other shapes based on the needs of an application or space availability. 
     In the exemplary embodiment, the center axis  39 ,  43  are arranged on a diametral axis  33 . The diametral axis  33  is the mid-plate or symmetry plane of the axis  37  of cylinder  24 . The valve plate  28  further includes a trepan  35  arranged circumferentially around the suction port  32  and discharge port  34 . The trepan  35  is an annular cutout that assists in the sealing of the valve to the valve seat, and in the opening of the valve by reducing the effect of the oil stiction (surface tension) force. 
     Arranged between the valve plate  28  and the crank case is a seal  30  to prevent the leakage of gas from the cylinder  24 . The compressor  20  also includes a valve, such as a suction reed valve  36 . The valve  36  includes a body  38  having a longitudinal axis  40 . A first end  44  of the body  38  is coupled between the crankcase  22  and the valve plate  28 , such as by a pin  42  for example. The body  38  also includes a second end  46  opposite the first end  44 . The second end  46  is positioned in a recess  48  in the crankcase  22 . The body  38  further includes a seal portion  50  that is sized and shaped to cover the suction port  32  and valve seat in the valve plate  28 . The seal portion  50  is generally coaxial with the center axis  39  of suction port  32 . The valve  36  is made from a suitable material to allow flexure of the body  38  at desired pressures during operation. 
     The valve  36  is rotated about the center axis  39  of the suction port  32  such that the longitudinal axis  40  of valve  36  is on an angle  41  relative to the diametral axis  33 . It should be appreciated that the rotating or skewing of the valve  36  so that the valve  36  is no longer on the diametral axis provides advantages in increasing the amount of space available for the discharge port  34 . In one embodiment, the discharge port is located on the diametral axis, thereby providing for the most space between the suction port and the discharge port. In other embodiments, the valve is skewed and the discharge port is not located directly on the diametral axis. These embodiments still provide for additional space between the suction port and the discharge port. 
     The crankcase  22  includes a first relief, such as chamfer  52 , formed on the edge of the cylinder  24  adjacent the valve  36  first end  44 . A second relief, such as chamfer  54 , is formed inside the recess  48  at the edge of cylinder  24 . In the exemplary embodiment, each relief is in the form of a chamfer  52 ,  54 , however, other relief shapes that provide support for the valve  36  may also be used, such as a radius for example. In one embodiment, the chamfers  52 ,  54  are substantially perpendicular to the longitudinal axis  40 . As will be discussed in more detail below, the chamfers  52 ,  54  provide advantages in supporting and reducing the stresses on the valve  36  when the valve  36  is in an open position. 
     A second valve, such as discharge reed valve  56  is mounted to the valve plate  28  on first surface  29 , such as by a bolt  58  for example. The discharge valve  56  is similar to the valve  36  in that it is sized and shaped to cover and seal the discharge port  34 . The discharge valve  56  is made from a suitable material to allow flexure of the discharge valve  56  at desired pressures during operation. 
     The valve plate  28  is supported by a bulkhead or wall  60  that is coupled between the valve plate  28  and an end housing  62 . The wall  60  provides support to the valve plate  28  against the high-pressure gas in the cylinder  24  during operation. The wall  60  further separates a suction plenum  64  from a discharge plenum  66  and is sized to withstand the pressure differential between the plenums  64 ,  66 . In the exemplary embodiment, the wall  60  is substantially parallel to a second diametral axis  68  of cylinder  24 . The diametral axis  68  is substantially perpendicular to the first diametral axis  33 . 
     During operation, the piston  26  moves linearly within the cylinder  24 . As the piston  26  moves away from the valve plate  28  causing a decrease in pressure in the cylinder  24 , the valve  36  bends in reaction to this decrease in pressure causing the seal portion  50  to move away from the suction port  32 . The valve  36  continues to bend from the first or initial position  70  until the second end  46  contacts the second chamfer  54  at a second or open position  72  ( FIG. 4 ). The chamfers  52 ,  54  provide advantages in reducing the stress on the valve  36  when in the open position  72 . The chamfers  52 ,  54  provide a surface to support the valve  36  rather than a sharp edge. Further, since the chamfers  52 ,  54  are substantially perpendicular to the longitudinal axis  40 , twisting of the valve  36  is minimized or eliminated. The chamfers  52 ,  54  improve the support of the valve  36  in the skewed position from the diametral axis  33 , thus allowing more space for the discharge port  34  while also providing the level of support for the valve  36  that is comparable or improved over valves that are aligned on the diametral axis. 
     As the seal portion  50  disengages from the suction port  32  and valve seat, gas from the suction plenum may flow into the cylinder  24 . The piston  26  will eventually reverse motion and move towards the valve plate  28  causing the valve  36  to return to the initial position  70 . As volume of the cylinder  24  decreases, the pressure of the gas in the cylinder  24  increases until the discharge reed valve bends, opening the discharge port  34  to allow pressurized gas to flow into the discharge plenum  66 . 
     Another embodiment compressor  80  is illustrated in  FIG. 7 . Similar to the embodiment described above, a crankcase  90  includes a cylinder  91  with a valve plate  92  arranged on one end. In this embodiment, the suction port  82  is positioned on a diametral axis  84 . A valve  86  is arranged with a first end  88  mounted between the crankcase  90  and the valve plate  92  above a chamfer  89  in the crankcase  90 . The valve  86  also includes a second end  94  arranged above a relief or chamfer  96  in the crankcase  90 . A seal portion  98  covers the suction port  82  when the valve  86  is in the closed position. A longitudinal axis  100  extends the length of the valve  86 . The valve  86  is rotated about the center  87  of suction port  82  such that the longitudinal axis  100  is on an angle  110  relative to the diametral axis  84 . 
     The discharge port  102  is arranged in the valve plate  92  on the opposite side of a bulkhead wall  104  from the suction port  82 . The wall  104  is substantially perpendicular to the diametral axis  84 . In this embodiment, the discharge port  102  is offset from the diametral axis by a distance  106 . In one embodiment, the offset distance  106  is arranged to maximize the diameter of the discharge port  102  without the trepan  108  interfering with the wall  104 . This embodiment also provides the advantage in that the angle  110  between the diametral axis  84  and the longitudinal axis  100  is reduced while allowing the discharge port  102  to be appropriately sized. 
     Yet another embodiment compressor  120  is illustrated in  FIG. 8 . Similar to the embodiments described above, a crankcase  122  includes a cylinder  124 . A valve plate  126  having a suction port  128  and a discharge port  130  is mounted to one end of the crankcase  122 . The suction port  128  is positioned on the diametral axis  132  on one side of a bulkhead wall  134 . A valve  136  having a first end  138  is mounted between the crankcase  122  and the valve plate  126  above a relief or chamfer  140  in the crankcase  122 . A valve  136  second end  142  is arranged above a second relief or chamfer  144 . A seal portion  146  covers the suction port  128  when the valve  136  is in the closed position. Similar to the embodiments above, the valve  136  is rotated about the center  148  of the suction port  128  such that a longitudinal axis  150  is on an angle  152  relative to the diametral axis  132 . 
     The discharge port  130  is arranged on a side of the wall  134  opposite the suction port  128 . The discharge port  130  is offset a distance  154  from the diametral axis  132 . An axis  156  is defined between the center  158  of the discharge port  130  and the center  148  of the suction port  128 . In this embodiment, the wall  134  is arranged substantially perpendicular to the axis  156 . This provides an advantage by allowing the offset distance  154  for discharge port  130  to be increased without the discharge trepan  160  interfering with the wall  134 . As a result, the angle  152  of the valve  136  may be further reduced. In some embodiments, the rotation of the wall  134  may also have additional advantages by creating additional space to increase the thickness of the wall  134 . As a result, higher differential pressures may be achieved between the suction plenum and the discharge plenum. 
     As disclosed, some embodiments of the invention may include some of the following advantages: an ability to utilize a larger discharge port; improved support for a valve; more efficient operation of the compressor; and an increased bulkhead wall thickness allowing for higher differential pressures during operation. 
     While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.