Abstract:
A pump has a pump assembly for pumping fluid. The pump assembly includes a fluid pressure changing mechanism in fluid communication with a valve plate which is in fluid communication with a port plate. A pair of flappers are interposed between and sealable with the valve plate and port plate. A head has a head port, and is in sealed engagement with the port plate, so that, in cooperation with the port plate and the valve plate, the flappers control fluid flowing through the head port and to and from the fluid pressure changing mechanism. Rotation of the port plate and valve plate relative to the head reverses flow of the fluid through the head port.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]    This application claims the priority benefit of U.S. Provisional Patent Application No. 60/223,812 filed on Aug. 8, 2000. 
     
    
     
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
         [0002]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates to piston pumps and compressors, and more particularly to a pump with a reversible port function.  
           [0004]    Small-scale fluid pumps are used for many consumer applications. A typical type of pump for these purposes use a wobble piston. Examples of such pumps are found in U.S. Pat. No. 3,961,868, issued Jun. 8, 1976 to Arthur J. Droege, Sr. et al, for “Air Compressor” and U.S. Pat. No. 4,842,498, issued Jun. 27, 1989 to Roy J. Rozek, for “Diaphragm Compressor”.  
           [0005]    In a typical pump, a pump assembly includes a piston which reciprocates in a cylinder to compress air. The piston is a plastic connecting rod having a piston end disposed in the cylinder, and a connecting end connected to an eccentric metal pin mounted to a shaft. As the shaft rotates, the connecting rod having a piston head disposed in a cylinder reciprocates to compress air. A head member in fluid communication with the cylinder feeds air into the cylinder through an intake port, and provides an escape for compressed air through an exhaust port, and ultimately to an outlet in the head member.  
           [0006]    Pumps are typically configured to pump fluid in one direction, that is to provide compressed air, or to provide suction and create a vacuum. Providing a pump which compresses air often requires a different arrangement of parts than a pump which provides a vacuum. As a result separate assembly lines, or at least careful coordination of parts in assembly, is required to produce the desired pump configuration. Therefore, a need exists for a pump having a pump assembly which can be easily reconfigured between a compressor configuration and a vacuum configuration without requiring different parts for each configuration.  
         SUMMARY OF THE INVENTION  
         [0007]    The present invention provides a pump having a pump assembly for pumping fluid. The pump assembly includes a fluid pressure changing mechanism in fluid communication with a valve plate which is in fluid communication with a port plate. A flapper is interposed between the valve plate and port plate and in sealing engagement with the valve plate and the port plate. A head having a head port is in sealed engagement with the port plate. In cooperation with the port plate and the valve plate, the flapper controls fluid flowing through the head port and to and from the fluid pressure changing mechanism. Rotation of the port plate and valve plate relative to the head reverses flow of the fluid through the head port.  
           [0008]    A general objective of the present invention is to provide a pump assembly which is easily reconfigured between a compressor configuration and a vacuum configuration. This objective is accomplished by providing a pump having a pump assembly having a cylinder and port plate which can be rotated relative to a head to reverse the flow of fluid through the pump assembly.  
           [0009]    The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 is a front perspective view of a pump incorporating the present invention with one cover half removed;  
         [0011]    [0011]FIG. 2 is rear perspective view of the pump of FIG. 1;  
         [0012]    [0012]FIG. 3 is a front perspective view of a pump frame for the pump of FIG. 1;  
         [0013]    [0013]FIG. 4 is a perspective view of the pump frame of FIG. 2;  
         [0014]    [0014]FIG. 5 is a partial perspective view of an interior surface of the pump housing of FIG. 1;  
         [0015]    [0015]FIG. 6 is a sectional view of the mounting arms of the pump frame engaging the pump housing;  
         [0016]    [0016]FIG. 7 is a perspective view of the cylinder, valve plate, flapper, port plate, gasket, and head of FIG. 1 assembled together;  
         [0017]    [0017]FIG. 8 is an exploded perspective view of the assembly of FIG. 7;  
         [0018]    [0018]FIG. 9 is a cross-sectional view along line  9 - 9  of FIG. 7;  
         [0019]    [0019]FIG. 10 is a plan view of the gasket of FIG. 8;  
         [0020]    [0020]FIG. 11 is a plan view of the head side of the port plate of FIG. 8;  
         [0021]    [0021]FIG. 12 is a plan view of the flapper of FIG. 8; and  
         [0022]    [0022]FIG. 13 is a top plan view of the valve plate of FIG. 8. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Referring to FIGS.  1 - 13 , a pump  10  having a pump assembly  12  includes an electric motor  14  having a rotatable shaft  16  which drives an eccentric assembly  18 . The eccentric assembly  18  includes an eccentric pin  20  journalled in a bore  22  formed in a connecting block  24  of a connecting rod  26  which forms a lower end of a wobble piston  30 . The piston  30  operates in a cylinder  32  to change the pressure of fluid disposed in the cylinder  32 . A valve plate  35  (shown in FIGS. 8 and 13) integrally molded on the end of the cylinder  32 , and in fluid communication with the interior of the cylinder  32 , sealingly engages a head assembly  34 . The head assembly  34  includes a port plate  36  which can be rotated with the valve plate  35  relative to the head  146  to reverse the flow of fluid pumped by the piston  30 . Two housing halves (one half  38  shown) are mounted to the motor  14  to enclose the pump assembly  12 .  
         [0024]    The motor  14  includes a coil winding  40  supported between upper and lower motor end brackets  42 ,  44 . The coil winding  40  surrounds a laminated core (not shown) fixed to the motor shaft  16 . The motor shaft  16  mounts a fan  46  at one end and the eccentric assembly  18  at the other end. Rotation of the shaft  16  drives the eccentric assembly  18  which reciprocatively drives the piston  30 .  
         [0025]    Referring to FIGS.  1 - 4 , each molded bracket  42 ,  44  also functions as a pump frame, and includes an annular plate  48  having a center opening  50 . The center opening  50  is surrounded by a integral circumferential skirt  52 . A bearing  54  is disposed in the center opening  50  to support the shaft  16  extending therethrough. The skirt  52  engages the coil winding  40  to secure it between the brackets  42 ,  44 . The annular plate  48  can include additional openings  56  to allow air blown by the fan  46  to pass over the coil winding  40  and laminated core, and cool the motor  14 .  
         [0026]    Multi-purpose mounting arms  58  extending from the skirt  52  at each bracket  42 ,  44  to provide alternatives for mounting the housing halves  38  to the pump assembly  12 . A slot  68  opening into side  60  can receive a nut (not shown) in the widened part of the slot for threadably engaging a screw (not shown) extending through a hole  70  formed in the end of arm  58 . Alternatively, as shown in FIGS. 5 and 6, the arm  58  can be received in receptacles  72  formed on an inner surface  74  of the housing half  38  to support the housing half  38  enclosing the pump assembly  12 , without fasteners connecting the arms  58  to the housing halves  38 .  
         [0027]    As shown in FIGS. 1, 2,  5 , and  6 , the housing halves  38  are mounted around the pump assembly by slipping each arm  58  formed on the brackets  42 ,  44  into an inwardly open receptacle  80  formed on each housing half inner surface  82 . The arms  58  support the housing halves  38  which are clamped together using screws (not shown). The screws are inserted into apertures (not shown) formed in one housing half  38 , and threadably engage screw bosses  34  in the other housing half  38 .  
         [0028]    Cup-shaped elastomeric boots  84  fitted over the arms  58  are interposed between the arms  58  and housing receptacles  80  (shown in FIG. 6) to dampen vibrations generated by the pump assembly  12 , and prevent the vibrations from propagating to the housing halves  38 .  
         [0029]    Referring back to FIGS. 3 and 4, the pump frame  42  includes a support base  86  for mounting the cylinder  32  and head assembly  34  thereto. The square base  86  is formed as an integral part of the frame  42 , and is offset from an axis  43  defined by the plate center opening  50 . The base  86  includes a support plate  90  perpendicular to a radial  45  extending from the axis  43 . Outwardly extending sides  92  extend at a right angle from each edge  94  of the plate  48 . An opening  96  is formed in the base plate  90  through which the piston  30  extends from the eccentric assembly  18  into the cylinder  32 . Adjacent base sides  92  are joined at corners  98 , and legs  100  extend from each corner  98 . Threaded bores  102  formed in a distal end  104  of each leg  100  threadably engage screws  106  (shown in FIG. 1) which secure the head assembly  34  thereto.  
         [0030]    Referring to FIG. 3, cylinder guides  108  are formed as an integral part of the plate  90 , and extend from one base  92  side to the adjacent base  92  side around each leg  100 . The plate  90  supports the cylinder  32 , and the guides  108  position the cylinder  32  with respect to the opening  96  for receiving the piston  30  therein.  
         [0031]    The piston  30  may be of the style and form, such as disclosed in U.S. Pat. No. 5,213,025 issued May 25, 1993 to Roy J. Rozek, for “Conical Rod Piston”. Preferably, the piston connecting rod  26  including the connecting block  24  formed as an integral part of the connecting rod  26 , and has the bore  22  formed in the block  24  for journaling the eccentrically mounted pin  20 . The piston  30  is formed by providing a piston end (not shown) on the rod section end  110  opposite the connecting block  24 , and the frustoconical connecting rod piston end reciprocates in the cylinder  32  to draw fluid into the cylinder  32  and force fluid out of the cylinder  32 . Although a piston reciprocating in a cylinder is disclosed, other mechanisms for changing the pressure of a fluid can be used, such as a diaphragm pump, without departing from the scope of the present invention.  
         [0032]    Looking at FIGS.  7 - 13 , the cylinder  32  has an open end  114  and a closed end  116  connected by the cylindrical wall  118 . Four pairs  120  of guide posts  122  extend outwardly from the cylindrical wall  118 , and engage the base cylinder guides  108  to align the cylinder  32  with the base opening  96 . Each guide post  122  of a pair  120  of guide posts  122  extends from the cylinder wall  118  proximal the cylinder open end  114 , and at a right angle to the other post  122  of the pair  120  to capture one of the guides  108  therebetween.  
         [0033]    The valve plate  35  is formed as an integral part of the cylinder  32  on the cylinder closed end  116 , and includes an inlet aperture  124  and an outlet aperture  126  formed therein. Inner curbs  128  surrounding each aperture  124 ,  126  positions a flapper construction  130  with an integral flapper gasket  132  on the valve plate  35 . The flapper gasket  132  is received in a groove  134  formed between the inner curbs  128  and an outer curb  129  surrounding the inner curbs  128  and apertures  124 ,  126 .  
         [0034]    Alignment posts  136  extending upwardly from the valve plate  35  engage alignment holes (not shown) formed in the port plate  36  of the head assembly  34  to properly align the head assembly  34  with the inlet and outlet apertures  124 ,  126 . The alignment posts  136  are offset from the valve plate center, such that the valve plate  35  can be assembled with the port plate  36  in only one orientation. Keying the valve plate  35  to the port plate  36 , such that the plates  35 ,  36  can be assembled in only one orientation, ensures that the ports  142 ,  148  in the port plate  36  are aligned with the proper apertures  124 ,  126  in the valve plate  35 .  
         [0035]    As shown in FIGS. 8 and 9, the flapper construction  130  is disposed between the valve plate  35  and the head assembly  34  to maintain fluid flow in the desired direction through the pump assembly  12 . The molded flapper construction  130  has a pair of flexible flappers  140  surrounded by the gasket  132 . When the pump assembly  12  is assembled, each flapper  140  is surrounded by one of the inner curbs  128 , and the groove  134  surrounding the apertures  124 ,  126  and curbs  128  receives the gasket  132 . Although a flapper construction  130  formed as a single molded piece is disclosed, other flapper construction, such as a construction having a pair of flappers which are not joined, can be used without departing from the scope of the present invention.  
         [0036]    The flapper construction  130  prevents fluid compressed in the cylinder  32  from exiting the cylinder  32  through the inlet aperture  124 , and prevents fluid from being drawn into the cylinder  32  through the cylinder outlet aperture  126 . When fluid is being drawn into the cylinder  32 , the flapper  140  disposed adjacent the outlet aperture  126  is drawn against the outlet aperture  126  preventing fluid from passing therethrough. When fluid is forced out of the cylinder  32 , the flapper  140  disposed adjacent the inlet aperture  124  is forced against an inlet port  142  in the port plate  36 , and blocks fluid from passing through the inlet port  142 .  
         [0037]    The head assembly  34  includes the port plate  36  and a head  146 . The port plate  36  sealingly engages the flapper gasket  132 , and cooperates with the flappers  140  to direct fluid flow to and from the cylinder  32 . The inlet port  142  and an outlet port  148  are formed in the port plate  36 , and extend between a port plate cylinder side  150  and a head side  152 . The screws  106  (shown in FIG. 1) threadably engaging the threaded bores  102  formed in each base leg  100  extend through holes  154  formed in each corner of the port plate  36 .  
         [0038]    The port plate cylinder side  150  includes the alignment holes and a circular guide wall  158  which extends from the port plate cylinder side  150  to circumferentially engage the cylinder wall  118 . The circular guide wall  158  has a diameter slightly larger than the outer diameter of the cylinder wall  118 . Preferably, a plurality of fingers (not shown) extend axially in the annular space defined by guide wall  158  guide the valve plate  35  formed on the cylinder closed end  116  within the guide wall  158  to align the apertures  124 ,  126  with the port plate ports  142 ,  148 .  
         [0039]    The port plate head side  152  includes a curb  162  surrounding each of the ports  142 ,  148 , and an outer groove  164  surrounding the curbs  162 . Two center grooves  168 ,  170  connect the outer groove  164  between the ports  142 ,  148  and respective curbs  162 . A center wall  156  is formed between the center grooves  168 ,  170  and curbs  162 , and defines a lengthwise edge of each center groove  168 ,  170 . A registration opening  172  formed in each curb  162  receives a finger  174  extending from a port plate gasket  176  received in the grooves  164 ,  166 .  
         [0040]    The port plate gasket  176  is received in the outer groove  164  surrounding the ports  142 ,  148 , and has a center member  180  which is received in one of the center groove halves  168 ,  170 . An inwardly extending finger  182  extending from one side of the gasket  176  is received in the registration opening  172  of one of the curbs  162  to seal around a chamber of the head  146  receiving fluid through the outlet port  148  of the port plate  36 .  
         [0041]    Preferably, as shown in FIG. 11, indicators  184  are provided to inform an operator which registration opening  172  should be filled for the desired configuration. In the embodiment shown in FIG. 11, a “V” is formed in the port plate head side  152  adjacent the registration opening  172  which receives the finger  182  when a vacuum configuration is desired, and a “P” is formed in the port plate head side  152  adjacent the registration opening  172  which receives the finger  182  when a pump configuration is desired.  
         [0042]    As best shown in FIG. 9, the head  146  sealingly engages the port plate  36  and is in fluid communication with the ports  142 ,  148 . The head  146  includes a first chamber  186  and a second chamber  188  divided by a wall  190 . The wall  190  divides the chambers  186 ,  188 , and when engaging the port plate  36 , slips into one of the center groove halves  168 ,  170  to sealingly engage the port plate gasket center element  180 . Preferably, the head  146  is formed from plastic, such as glass reinforced polyethylene teraphthalate.  
         [0043]    The first chamber  186  is in fluid communication with one of the port plate ports  142 ,  148 , a head port  192 , a pressure relief valve  194 , and a pressure switch port  196 . The head port  192  connects, such as through a hose (not shown), to a device (not shown) requiring pressurized fluid, such as an air brush, or a device requiring suction, such as an aspirator, to provide fluid communication between the first chamber  186  and the device. The pressure relief valve  194  releases pressurized fluid above a predetermined level to avoid damage to the assembly  12 . The pressure switch port  196  is for connecting to a pressure switch  200  (shown in FIGS. 1 and 2). Although a pressure switch port  196 , pressure switch  200 , and pressure relief valve  194  are shown, they are not required to practice the invention.  
         [0044]    The second chamber  188  is in fluid communication with outside air through an open port  202  which acts as an inlet port or an exhaust port depending upon the direction of fluid flow through the pump assembly  12 . For example, in the pump configuration when the pump assembly  12  provides pressurized air through the head port  192 , air is drawn into the second chamber  188  through the open port  202 , and pumped into the first chamber  186  by the piston  30 . In the vacuum configuration, when the head port  192  draws a suction, air is pumped from the first chamber  186  into the second chamber  188  by the piston  30 , and is exhausted to the atmosphere through the open port  202 . Of course the open port  202  can be in fluid communication with a container (not shown) containing a fluid which is pumped by the pumping assembly  12 , or for receiving a fluid which is suctioned by the pump assembly  12 .  
         [0045]    Holes  204  formed in each corner  206  of the head  146  are aligned with the holes  194  formed in the port plate  36 . The screws  106  are inserted through the holes  154 ,  204 , and threadably engage the threaded bores  102  in the base legs  100  to sandwich the port plate  36  and the gasket  176  between the head  146  and base legs  100 . In addition, threadably engaging the screws  106  urges the port plate  36  against the valve plate  35  to sandwich the flapper construction  130  therebetween.  
         [0046]    In use, the pump assembly  12  can be configured to pump (compress) fluid or to draw fluid (create a vacuum) through the head port  142 . In the compressor configuration, the first chamber  186  is positioned over the port plate outlet port  148 , and the second chamber  188  is positioned over the inlet port  142 . Preferably, the registration opening  172  adjacent the “T” receives the finger  182  extending from the port plate gasket  176 . As a result, when the electric motor  14  drives the eccentric assembly  18  and causes the piston  30  to reciprocate, fluid is drawn into the cylinder  32  from the second chamber  188  through the inlet port  142 , and exhausted into the first chamber  186  from the cylinder  32  through the outlet port  148 . The pressurized fluid in the first chamber  186  passes through the head port  192  to the device requiring pressurized fluid.  
         [0047]    In a vacuum configuration, the first chamber  186  is positioned over the port plate inlet port  142 , and the second chamber  188  is positioned over the outlet port  148 . Preferably, the registration opening  172  adjacent the “V” receives the finger  182  extending from the port plate gasket  176 . As a result, when the electric motor  14  drives the eccentric assembly  18  and causes the piston  30  to reciprocate, fluid is drawn into the cylinder  32  from the first chamber  186  through the inlet port  142 , and exhausted into the second chamber  188  from the cylinder  32  through the outlet port  148 . The fluid is drawn into the first chamber  186  through the head port  192  from the device requiring suction.  
         [0048]    In order to change between pump assembly configurations, and reverse the direction of fluid flow, the port plate  36  and cylinder  32  are rotated 180° relative to the head  146 . More particularly, the screws  106  securing the head  146  to the base  86  are disengaged from the base leg threaded bores  102 , and the head  146  is pulled away from the port plate  36  and cylinder  36 . The cylinder  36  is pulled away from the cylinder guides  108  formed in the base  86 , such that the cylinder guide posts  122  disengage from the guides  108 , and the cylinder  32  can be rotated about the cylinder cylindrical axis.  
         [0049]    The cylinder  32 , and thus the valve plate  35 , and port plate  36  are rotated 180° relative to the head  146 , and then the cylinder  32  is slipped back between the cylinder guides  108 , such the posts  122  reengage the guides  108 . Rotating the port plate  36  180° relative to the head  146  aligns the port plate ports  142 ,  148  with a chamber  186 ,  188  in the head  146  which is different from the chamber  186 ,  188  aligned with the port  142 ,  148  prior to rotation. Realigning the ports  142 ,  148  with a different chamber  186 ,  188  changes the flow of fluid through the head  146 .  
         [0050]    Once the port plate  36  and cylinder  32  are repositioned, the gasket  176  received in the grooves  164 ,  166  formed on the head side  152  of the port plate  36 , and having the gasket finger  182  inserted into one of the registration openings  172 , is pulled out of the grooves  164 ,  166 . The gasket  176  is then reinserted into the grooves  164 ,  166 , such that the finger  182  is inserted into the other registration opening  172 .  
         [0051]    The head  146  is then repositioned adjacent the port plate  36 , and the screws  106  are inserted through the holes  154 ,  204  to threadably engage the threaded bores  102  in the base legs  100 . The screws  106  are tightened to sandwich the port plate  36  between the base  86  and the head  146 , and sealingly engage the head  146  with the gasket  176 . Advantageously, by rotating the valve plate  35  and port plate  36  relative to the head  146 , ports extending from the head do not move relative to other pump assembly components and the housing.  
         [0052]    While there has been shown and described what are at present considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims. For example, a gasket can be provided which is received in the entire grooved area of the port plate, such that repositioning the gasket is not required when changing the pump assembly configuration. In addition, the valve plate  35  can be provided as a separate piece from the cylinder  32 , such that rotating the valve plate  35  and port plate  36  relative to the head  146  changes the direction of fluid flow through head  146  without rotating the cylinder  32 .