Abstract:
Besides the conventional pump timing in rotary hydraulic devices, a series of constant and variable restrictions have been applied to condition the pressurized flow used to internally precompress the volume or volumes to be displaced. This multiple staged orifices feature reduces the outgassing associated with the pressurized flow passing through a single restriction, such as a metering groove. The pressurization of the outgassed fluid will cause noise and erosive wear of the pump internal containment surfaces.

Description:
The present invention is directed to rotary hydraulic devices capable of functioning as pumps, motors, flow dividers, pressure intensifier and the like, and more particularly to vane and gear pumps. 
   BACKGROUND AND OBJECTS OF INVENTION 
   Most of the conventional positive displacement rotary pumps apply single stage pressurized flow to hydrostatically precompress the internal fluid volume to be displaced. The throttled pressure of a single staged flow contributes to the release of dissolved air into the internal pump volume to be displaced. The entrained air bubbles are imploded during the pump precompression and discharge cycles. Noisy operation and erosive wear are encountered. 
   To reduce the outgassing in the pressurized flow encountered in the precompression cycle, a series of constant and variable restrictions are located in the flow passage to alter the throttled pressure. 
   The application of the progressive staged flow for precompressing the internal pump volume to be displaced is described in typical vane, gerotor, and spur gear pumps. The invented precompressive staged flow feature is also applicable in other positive displacement rotary pump designs. 
   SUMMARY OF THE INVENTION 
   The present invention can be applied to most positive displacement rotary pumps, which feature transition zones between the inlet and discharge periods. During the inlet to outlet transition zone the pump volume to be displaced needs to become pressurized to that of the discharge pressure. The conventional method for compressing this volume is to provide pressurized flow through designed metering grooves on the valve face. When the pump intake volume is not completely filled the metering groove provide the single restrictive orifice for the displaced fluid to suddenly return and complete the pump filling; this rapid reversed flow is associated with increased outgassing and turbulence that produce cavitation wear and noisy operation. 
   The present invention consists of providing pressurized flow through multistaged restrictive openings to precompress the volume to be displaced. With multistaged orificing the precompressive flow contains considerably less outgassing, which results in quieter operation and reduced erosion wear. 
   A rotary vane hydraulic device generally includes a housing, a rotor mounted for rotation within a housing and a plurality of vanes individually slideable disposed in corresponding radially extending peripheral slots in the rotor. A cam ring radially surrounds the rotor and has an inward directed surface forming a vane track and one or more fluid pressure cavities between the cam surface and rotor; also there are one or more corresponding fluid inlet cavities. In such devices the vanes as followers are adapted to follow the cam track and provide proper sealing between the inlet and outlet porting correlated with the fluid inlet and fluid outlet zones. During operation of such device, the vanes are urged outwardly and into engagement with the cam track by centrifugal force and also by providing a controlled pressure unbalanced condition between the vane tip engaging the cam surface and the inner surface of the vane within the rotor slot. 
   Inlet and outlet passages in the housing feed and receive hydraulic fluid to and from the cavity or cavities within the rotating displacement pump. 
   In most conventional vane pumps the intervane volumes in transition zone of inlet to discharge oil are precompressed to the discharged pressure by throttled discharge flow via a metering groove located at the beginning of the outlet port. The resulting single pressure staged throttled flow contains a considerable amount of outgassing, which causes audible noise and erosive wear attributed to the implosion of the formed gas bubbles during pressurization. 
   One of the principle objectives of the present invention is to provide a rotary flow restrictive feature in vane pumps that reduces the outgassing during precompression. The multistaged restrictions in the interfaced porting reduces the amount of outgassing in the fluid volume to be displaced during precompression. 
   The present invention consists of a rotor with porting that registers with strategically located access ports in the pump valve faces of the axial containment surfaces and directs pressurized fluid flow through a series of variable and constant restrictions to precompress each intervane volume prior to displacement. 
   Each rotor vane slot segment has a radial port located on the periphery and directed inward to intersect with an axially directed passage which exits at both sides of the rotor to provide two axial ports. 
   On each pump valve face two access ports are radially and angularly located to correspond to the axial ports of two consecutive rotor vane slot segments. One access port strategically located in the inlet to discharge transition zone; the other access port is strategically located in the displacement zone. Both of the access ports are connected by a passage located beneath or on the surface of the valve face. 
   When the intervane volume is sealed from the inlet port, the axial ports in the rotor begin to register with the corresponding access ports on the valve faces. Pressurized flow enters the radial port in the rotor and is directed through the axial ports into the access ports in the valve face. This pressurized flow continues through the connecting passage and out the access ports located in the inlet to pressure transition zone and into the registered opening of the axial ports and out the radial port in the rotor. The throttled pressurized flow enters and precompresses the intervane volume of fluid in the inlet to discharge transition zone. 
   The radial porting in the rotor segments, the varied opening of the axial ports in the rotor registering with the access port in the valve faces, and the connecting passage provide the multistaged restrictions for reducing the outgassing associated with throttled pressurized flow. 
   The afore-described precompression flow sequence occurs for each intervane volume of single and multi-displacement cycles per revolution vane units. 
   A simplified and preferred version of the afore-described design would replace the axial passage and its axial ports with radial grooves open to the outside diameter on both sides of the rotor. The arcuately shaped corresponding access grooves on the side plate would register with the radial grooves on the rotor and provide the multistage restrictions to meter the pressurized flow into the intervane volumes to be displaced. 
   The gerotor is positive displacement gear type unit consisting of two elements, an inner rotor and an outer rotor. The outer rotor has one or more teeth than the inner rotor and has its centerline positioned at fixed eccentricity from the drive axis of the inner rotor and shaft. 
   Although gerotor units come in a variety of geometric configurations, materials, and sizes all gerotor sets possess the basic principle of having conjugately-generated tooth profiles which provide continuous fluid-tight sealing during the pumping operation. 
   As the rotors rotate about their respective axes, fluid is drawn from the inlet port into the enlarging intertooth space to its optimum volume. When the intertooth space is sealed from the inlet port, it becomes subjected to precompression by multistaged metering flow from the discharge chamber. This metered flow is directed through multistaged restrictions to minimize the outgassing associated with pressurized flow passing through a single stage metering groove. The multistaged restrictions consist of a radial port centrally located on the minor diameter of the inner rotor and between each pair of teeth. Each radial port is inwardly extended to intersect an axial passage which created an axial port on both sides of the inner rotor. 
   Two access port are located on each axial retaining walls of the rotating group which consists of the inner and outer rotors. The access ports are located to radially and angularly correspond with at least two (2) consecutive axial ports of the inner rotor. On each axial retaining wall, an access port is located in the inlet to discharge transition zone and at a position to begin registering with axial port in the inner rotor when the intertooth space is sealed from the inlet chambers. On each axial retaining wall the other access port is located in the discharge zone to identically sequence its opening with the corresponding axial port. The access ports are connected with an arcuately shaped passage, which is located beneath or on the surface of the retaining wall. 
   When the two (2) consecutive axial ports begin registering with the two (2) access ports on the axial retaining walls, pressurized flow enters the radial port of the inner rotor and is axially directed to exit into the access ports in the axial retaining wall. The pressurized flow continues in the connecting passage to exit into the axial ports and through the radial port into the intertooth space that completed the inlet cycle and precompress the entrapped volume of fluid. 
   The continuously varied opening of the registered axial ports in the inner rotor with the access ports in the retaining walls and the selected sized connected passage provide the multistage restrictions for the pressurized flow to precompress each intertooth volume to be displaced. 
   A simplified embodiment of the present invention would replace the axial passage in the inner rotor with radial grooves on both sides of the inner rotor. The radial grooves would be open at the minor diameter and inwardly extended to register with the access ports on the retaining valve surfaces. 
   Another gear pump design consists of two spur gears accurately centered and closely fitted in a housing. The pumping chambers formed between the gear teeth are enclosed by a housing center section and side plates which possess the pump timing. 
   A partial vacuum is created in the pump inlet as the rotating gears unmesh. Fluid is drawn into the intertooth spaces and carried by the rotating gears to the region where the gears mesh and the entrapped fluid volumes are displaced. The pump timing on the side plates include grooves that originate at the discharge and surround the periphery above the minor diameter of both gears. This groove is terminated short of the inlet zone to allow for a minimum one tooth seal. This design strategy provides a radial hydrostatic pressure force to prevent the engaged gear teeth from mechanically separating because of the pressure angle of the meshed tooth engagement. Also, the wrap-around pressure distribution reduces the net radial hydrostatic pressure force supported by the journal bearings. 
   The present invention includes the following modification to the typical spur gear pump. At the minor diameter and between each pair of gear teeth a selected size radial groove is inwardly located on one side or both sides of the spur gear. An arcuately shaped access groove is located on the valve face of each side plate in the pressurized regions to correspond with the radial grooves in the gears. The beginning location of the access grooves in the side plate registers with the radial groove when the intertooth space completes its inlet cycle and the trailing tooth seals the discharge pressure from the inlet. The radial groove preceding the registering radial groove is engaged with the access groove in the side plate and discharged pressure flow will enter and meter out by the trailing radial groove into the intertooth space that completed the inlet cycle. The interfacing of the gear radial grooves and the access grooves on the side plate provide varied and constant openings (orifices) for throttling the pressurized flow to precompress the intertooth volumes to be displaced. 
   The aforementioned events are performed for each intertooth space completing its inlet cycle. 
   As an option, a pressure metering groove at the discharge pressure port of the side plates can be applied to supplement the multistaged precompression. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is an axial section view along the line  1 - 1  in  FIG. 2  of a pressure energy translating device, vane pump embodying the invention. 
       FIG. 1A  is a fragmental axial view of an alternative design for connecting flow path between access ports. 
       FIG. 1B  is an enlarged fragmental elevational view of the invention featuring an alternative means locating the precompressive flow porting design on the rotor sides and on the axial support surfaces. 
       FIG. 1C  is a section axial view along line  3 - 3  in  FIG. 1B . 
       FIG. 2  is a sectional elevational view taken along the line  2 - 2  in  FIG. 1 . 
       FIG. 2A  is an enlarged fragmental elevational view of porting supplying precompressive flow shown in  FIG. 2 . 
       FIG. 3  is a linear layout of the vane pump cycles and the embodying invention. 
       FIG. 4  is an axial section view line  4 - 4  in  FIG. 5  of a gerotor displacement unit embodying the invention. 
       FIG. 4A  is a fragmental axial view along line  4 A- 4 A in  FIG. 5  of an alternative design for connecting the access ports with a passage on the axial support surfaces. 
       FIG. 5  is a sectional elevation view of a gerotor displacement unit with the embodying invention. 
       FIG. 6  is an elevational view of gerotor displacement unit with the embodying invention showing an alternate design for connecting the precompression flow paths on the sides of the rotor and on the axial support surfaces. 
       FIG. 6A  is a fragmental axial section view along line  6 A- 6 A in  FIG. 6 . 
       FIG. 7  is an elevational view of a spur gear pump rotating group embodying the invention. 
       FIG. 7A  is a sectional axial view taken along line  7 A- 7 A in  FIG. 7 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Referring to  FIGS. 1 ,  2  and  3 , therein is shown a rotary sliding vane pump  20  comprising of a housing  21  and a cartridge subassembly  22 . The housing  21  comprises of a body  21   a  and cover  21   b . The cartridge  22  includes a cam ring  27  sandwiched between support plates side  23  and  24 . The body  21   a  provides an outlet connection port  19  which is directly connected to a discharge chamber  18  formed between the body  21   a  and the support plate  24 . The pair of discharge ports  34  in the support plate  24 . The pair of discharge ports  34  in the support plate  24  open into the discharge chamber  18 . The cover  21   b  provides a supply connection port  17  leading into a pair of fluid inlet openings  33  formed in support plates  23  and  24 . 
   A rotor  25  is rotatably mounted within cam ring  27  on the spline  16  of shaft  15  which is rotatably mounted within bearing  14  in support plate  23  and a ball bearing  14   a  mounted in body  21   a.    
   Cam ring  27  has an internal contour  28  which is substantially oval in shape and which together with the periphery of the rotor  25  and the adjoining axial support surfaces  46  and  47  define two radially opposing pumping chambers  42  and  43 ; each of which traverse the fluid inlet, fluid transition and fluid outlet zones which are displayed in  FIG. 3 . The fluid inlet zones comprise those portions of the pumping chambers  42  and  43  respectively registering with the fluid inlet ports  33  in the support plates  23  and  24 . The fluid discharge zones comprise those portions of the pumping chambers  42  and  43  registering respectively with the accurately shaped fluid discharge ports openings  34  in support side plates  23  and  24 . Fluid flows to inlet zones through inlet port  17  into the inlet chamber  44  through passages  33  formed in support plates  23  and  24  into the space between the internal contour  28  and the periphery of rotor  25 . 
   It has been the practice in devices of this type to provide the rotor  25  with a plurality of radial vane slots  45 , each of which has a vane  26  slideably mounted therein. The contour of cam ring  27  includes an inlet rise zone, an intermediate arcuate zone (precompression) an outlet fall zone, and another intermediate arcuate zone (decompression) which are shown in  FIG. 3 ; all of these portions constitute a pumping cycle. The cam contour is symmetrical about the minor axis; thus, each arcuate portions are duplicated in the other opposed portion of the contour. As the tips of the vanes  26  carried by the rotor  25  and the vane tips traverse the intervane spaces vary to correspond to the inlet rise, arcuate dells, and discharge fall zones dictated by the internal contour  28  of cam ring  27 . The spacing between each pair of vanes is adapted to span the distance between each port in both axial support surfaces  46  and  47  on support side plates  23  and  24  in a manner to provide proper sealing between the inlet and outlet chambers of the pumping device. 
   The pump cartridge  22  is fastened together by two (2) screws  50 . Screws  50  extend through support side plate  23  and cam ring  27  into threaded holes in support plate  24 . Screws  50  also locate the cam ring  27  to correspond to the pump timing on the valve faces  46 ,  47 , support side plates  23  and  24 . The installed cartridge  22  in pump assembly  20  is internally located by two stator pins  51  located in the support plate  23  and housing cover  21   b.    
   Referring to  FIGS. 1 ,  2  and  3 , the undervane chamber  38  of each vane is provided with fluid pressure by passage  36  in support side plates  24  and  23 . During the fluid discharge the vanes  26  are inwardly displaced by the internal contour  28  and the displaced undervane fluid volume is forced into passage  37  and out through restricted opening  40  into the discharge chamber  18 . The resulting increased pressure in the undervane chambers  38  assist the vanes  26  to maintain tip contact with the internal contour  28  during the fluid displacement. 
   Referring to  FIGS. 1 ,  2 ,  2 A and  3 , an axial passage  30  is located in each angular segment of rotor  25 . The axial passage  30  is continued through the length of the rotor  25  to create an axial port  30   a  on both sides of the rotor. A radial port  29  is inwardly located on the rotor periphery to intersect each axial passage  30 . Two (2) access ports  31  per pump cycle are located at each axial support surfaces  46  and  47 ; one access port  31  is located in the inlet to discharge (precompression) zone and the second access port  31  is located in the discharge zone. The angular and radial location of the two access ports  31  are strategically timed with the two consecutive axial ports  30   a  in rotor  25 . A sized passage  32  connecting access ports  31  is located beneath the axial support surfaces  46  and  47 . 
   When the intervane volume is located in the inlet to transition (precompression) zone and sealed from the fluid inlet ports  33  the axial ports  30   a  in rotor  35  begin to register with the access ports  31  in the valve faces  46  and  47 . Pressurized flow enters the radial port  29  in rotor  25  and is directed by the axial ports  30   a  to enter the access ports  31  and continues in passage  32  to exit in intervane volumes traversing the precompression zone. The openings of the radial ports  30   a,  connecting passage  32  and the varied opening between the registering access ports  31  with the axial port  30   a  provide the multistaged flow restrictions to reduce the outgassing of throttled pressurized flow. 
   As a design supplemental flow option a precompression pressure metering groove  39  can be located on one or both axial support surface faces  46  and  47 . The metering groove  39  is extended from the discharge port  34  into the inlet to discharge transition (precompression zone). 
   Referring to  FIG. 3 , another means to enhance the precompression is to include a fall  35  in the precompression zone of the internal contour  28  of cam ring  27 . As the intervane volume traverses the precompression zone its volume is gradually reduced and the trapped fluid is mechanically compressed. 
   Referring to  FIG. 1A , an alternate design would have the connecting passage  32  of access ports  31  replaced with an on the surface access groove  32   a.    
   Referring to  FIG. 1B  and  FIG. 1C  therein axial passage  30  and radial port  30   a  are replaced by inward radial grooves  61  on both sides of the rotor. The terminated end of the radial grooves  61  register with an access groove  31   a  on the axial support surfaces of the support side plates  23  and  24 . The access grooves  31   a  would eliminate the axial passages  30  and the accompanying axial ports  31 . 
   Referring to  FIGS. 4 ,  5  and  6  there is a gerotor gear type positive displacement device or pump  101  comprising of a housing  102  which consists of body  102   a  and cover  102   b  and a gerotor set  103  consisting of an inner rotor  104  and outer rotor  105  located radially and axially within housing  102 . The outer rotor  105  has one or more teeth than the inner rotor  104  and has its centerline positioned at a fixed eccentricity  106  from the centerline of the inner rotor  104  and drive shaft  107 . 
   The housing body and cover  102   a  and  102   b  possess the pump timing of inlet, transition of inlet to discharge (precompression), discharge, and transition of discharge to inlet (decompression) zones. The inlet connection port  108  is connected to the inlet chamber  109  and the outlet connection port  110  is connected to the discharge chamber  111 . 
   Referring to  FIG. 4 , therein is the inner rotor  104  with porting to achieve multistaged restrictions in directing pressurized fluid flow for precompressing the intertooth volumes prior to displacement. On the root diameter, radial passages  112  are located between each set of teeth to intersect with axial passage  113  which creates axial ports  113   a  on both sides of the inner rotor  104 . 
   Referring to  FIGS. 4 and 5  therein is pump housing  102  with the porting to achieve multistage restrictions for pressurized flow into the intertooth volume  114  to be displaced. The access ports  115  can be located on one or both axial support surfaces  116 ,  117 . The access ports  115  are located radially and angularly to correspond with two (2) consecutive axial ports  113   a  of the inner rotor  104 . On the axial support surfaces  116 ,  117  and access ports  115  are located in the inlet to discharge transition zone and at a position to begin registering with axial port  113   a  in the inner rotor  104  when the enlarged intertooth volume  114  is sealed from the inlet chamber  109 . The second access port  115  is located in the discharge zone to identically sequence its opening with the trailing axial port  113   a  in inner rotor  104 . The two access ports  115  on each support walls  116 ,  117  are connected with a sized passage  118  which are located beneath the axial support surfaces  116 ,  117 . 
   Referring to  FIGS. 4A ,  6  and  6 A, passage  118  is replaced with an alternative design passage  118   a  which is located on the support surfaces  116 ,  117 . 
   Referring to  FIGS. 4 and 5 , as the inner and outer rotor  104 ,  105  revolve about their respective axis, fluid is drawn from the inlet chamber  109  into the enlarging intertooth space  114  between the engaged teeth of the inner and outer rotors  104 ,  105 . When the intertooth space  114  is at its optimum volume it is sealed from the inlet chamber  109 . The axial ports  113   a  in the inner rotor  104  begin registering with both access ports  115  on the axial support surfaces  116 ,  117 . Pressurized flow from the discharge chamber  111  enters into the radial port  112  and is directed by the connected axial port  113  into the access ports  115  and through passages  118  to the connected access ports  115 . The pressurized flow enters the trailing axial port  113   a  and continues through the trailing radial port  112  into the intertooth space  114 , which is about to be reduced by the engaging teeth of the inner and outer rotors  104 ,  105 . The fluid volume in each intertooth space  114  is precompressed by the admitted conditioned flow prior to its displacement. The pressurized flow for precompression was directed through a series of restrictions which constituted the multistaged restrictions to minimize the outgassing associated with single staged throttling pressurized flow. 
   An optional pressure meter groove  120  is extended from the discharge  111  into the precompression zone to supplement the pressurized flow for precompressing the intertooth volume  114  prior to its displacement. 
   Referring to  FIGS. 6 and 6A , a preferred embodiment of the present invention is to replace the axial port  113  and radial port  112  in the inner rotor  104  with a strategic inward radial groove  112   a  on one or both sides located between each pair of teeth and at the root diameter. This radial groove and its ending would be sized and located to register with access groove  118   a.    
   Referring to  FIGS. 7 and 7A , therein pump assembly  230 , a partial vacuum is created in the pump inlet  214  as the rotating gears  216  unmeshed. Fluid is drawn into the intertooth spaces  211  and carried by the rotating gears  216  to the region  225  where the gears  216  meshed and the entrapped fluid volumes are displaced. The multistaged precompression of the intertooth volumes to be displaced is accomplished by communicating the pressurized pump discharge in port  220  with recessed and open grooves  212  located one or both axial support surfaces  213  and strategically terminated near the inlet port  214 . Inward radial grooves  215  are located between the gear tooth and on the minor diameters of the spur gears  216 . Two (2) arcuately shaped access grooves  217  are located on axial support surfaces  213  and diametrically extended to at least communicate between two (2) consecutive radial grooves  215 . The timing locations of the access grooves  217  are to engage the radial grooves  215  when the gear teeth  216  radially seals the intertooth volume  211  from the inlet  214 . As the radial groove  215  engages access groove  217  the discharged pressurized flow supplied by groove  212  is directed through radial groove  215  and through access groove  217  and out through the trailing radial groove  215  to precompress the intertooth volume  211  which completed the filling cycle and is radially sealed from the inlet  214  by the trailing gear tooth  216 . The timing and engagement of the radial groove  215  with access groove  217  creates a series of flow restrictions which diminishes the amount of outgassing of the dissolved gasses in the fluid during the precompression of each intertooth volume to be displaced. 
   The described porting of the staged precompression of the volume  211  to be displaced can be applied on one or both sides of the rotating spur gear displacement group  210 . 
   As a design supplemental flows option a precompression pressure metering groove  235  is extended from circular groove  212  toward the inlet port.