Vane pump with undervane feed

Information

  • Patent Grant
  • 6634865
  • Patent Number
    6,634,865
  • Date Filed
    Friday, September 28, 2001
    23 years ago
  • Date Issued
    Tuesday, October 21, 2003
    21 years ago
Abstract
A vane pump is disclosed for use with gas turbine engines which has pressurized fluid supplied to the undervane portion of the vane elements to balance the forces imparted thereon. The vane pump includes a pump housing, a cam member, a cylindrical rotor member and a chamber. The chamber is defined within the housing and positioned for fluid communication with the undervane portion of each vane element to provide a desired pressure thereto. The chamber is in fluid communication with a first pressure source and a second pressure source, wherein the first pressure source is associated with the discharge arc segment of the pumping cavity, and the second pressure source is associated with the inlet arc segment of the pumping cavity.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The subject invention relates to fuel pumps for gas turbine engines, and more particularly, to vane pumps wherein pressurized fluid is supplied to the undervane portion of the vane elements to balance forces imparted thereon.




2. Background of the Related Art




Fixed displacement and variable displacement pumps are used as main fuel pumps in the aviation gas turbine industry. An example of a fixed displacement vane pump is disclosed in U.S. Pat. No. 4,354,809 to Sundberg and a variable displacement vane pump is disclosed in U.S. Pat. No. 5,545,014 to Sundberg et al. The disclosures provided in these patents are herein incorporated by reference to the extent they do not conflict with the present disclosure.




Vane pumps traditionally include a housing, a cam member, a rotor and journal bearings. The housing defines an interior chamber, a fluid inlet and a fluid outlet and the cam member is disposed within the interior chamber of the housing and has a central bore which defines the circumferential boundary of the internal pumping chamber. Mounted for rotational movement within the central bore of the cam member, is a rotor supported by axially opposed journal bearings. Typically, the rotor element has circumferentially spaced apart slots machined therein which support corresponding radially-movable vane elements. The vane elements have a radially outer tip portion which slidably contacts the circumferential portion of the internal pumping chamber and a radially inner undervane portion.




In a single rotation, the vanes of the rotor element of the pump traverse at least four distinct arcuate regions which make up the 360 degree revolution. The first region is the inlet arc segment in which fluid is received into the pumping chamber and over this region the bucket volume increases. The second region is the discharge arc segment in which pressurized fluid is discharged from the pumping chamber and throughout this region, the bucket volume decrease. Lastly, seal arc segments separate the inlet and discharge arc segments and represent the arc segment through which the bucket volume remains substantially constant.




In operation, fluid at a first pressure is fed into the pumping chamber through the housing inlet, and into the space defined between adjacent vane elements, known as the bucket. In positive displacement vane pumps, as the vane elements rotate within the pumping chamber from the inlet region to the outlet region, the configuration of the cam member causes the vanes to retract within the corresponding slots. This causes the volume defined by the bucket to decrease. Since the amount of fluid received into an inlet bucket is greater than that contained within the corresponding discharge bucket, a fluid volume equivalent in size to the volumetric difference is discharged or displaced through the outlet port at a pressure equal to the downstream pressure which must be overcome.




Typically, pumping pressures and velocities are so high within a pump housing that the use of heavy, high wear resistant materials such as tungsten carbide for the vanes and cam member becomes necessary to handle the wear which is caused by these high levels of pressure and velocity.




During this rotation, a radially outward centrifugal force is exerted on the vane elements. At the same time, pressurized fluid within adjacent buckets acts to force the vane elements radially inward. Often, the forces applied to the vanes are not balanced and therefore, the vane tip is either subjected to excessive wear or fluid leaks from within the bucket. This reduces pumping efficiency.




The ideal operating condition for a pump is when the pressure applied to each vane element is balanced and each vane element “floats” within a corresponding slot in the rotor. This condition results in minimum wear to the vane tips and minimum pressure losses due to the lack of contact between the vane tips and the cam member.




Prior attempts at correcting the unbalanced vane condition have included applying pressure to the undervane portion of the vane. In general, the typical vane pump does not incorporate an undervane pumping feature. Those that do, typically supply pressure from within the buckets in the inlet region to the undervane portion of vanes within the inlet arc. Similarly, the undervane portion of the vanes within the discharge arc are supplied with pressure from the buckets located in the discharge arc. This feature creates a balanced condition within the inlet and discharge arc regions, but does not correct the unbalanced condition in the seal arc regions.




When the vanes are in the first seal arc region, which is located after the inlet arc region and before the discharge arc region, the leading face of the vane is subjected to pressure from the discharge side of the pumping chamber and the trailing face is subjected to pressure from the inlet side of the pumping chamber. Therefore supplying pressure from either the inlet or discharge arc regions will not balance the forces. In fact, an interim pressure equal to half the discharge pressure plus half the inlet pressure is required to balance the forces imparted on the vanes traversing the seal arc regions.




Examples of vane pumps having pressure-balanced vanes adapted to provide undervane pumping are disclosed in U.S. Pat. Nos. 4,354,809 and 5,545,014. The '809 patent discloses a vane pump incorporating undervane pumping wherein the vanes are hydraulically balanced in not only the inlet and discharge areas but also in the seal arcs. More specifically, the '809 patent discloses a fixed displacement vane pump which utilizes a series of ports machined in the rotor to supply the pressure to the undervane region. Two ports are provided in the rotor on the leading side of the blade and two ports are provided in the rotor on the trailing side of the blade. All of the ports fluidly communicate with the undervane portion of their associated vane element. Although, this configuration provides a balanced condition, ports having a complex configuration must be machined in the rotor at great expense. Also, in pumps which have a seal arc region with an arc length greater than the arc length between the leading and trailing ports, the pressure supplied to the undervane portion is not a mixture of the pressure from the inlet and discharge arc regions, but rather a mixture of the pressure from the seal arc region and either the discharge or inlet arc regions.




U.S. Pat. No. 5,545,014 to Sundberg et al. teaches a durable, single action, variable displacement vane pump capable of undervane pumping, components thereof and a pressure balancing method which is herein incorporated by reference. The '014 patent discloses the use of a servo-piston to supply half discharge pressure to the undervane portion of the vane elements when the vanes are positioned in the seal arc region.




In view of the foregoing, a need exists for an improved vane pump which cost effectively balances that forces exerted on each vane element in the inlet arc region, the discharge arc region and the seal arc regions.




SUMMARY OF THE INVENTION




The subject application is directed to vane pumps for use with gas turbine engines wherein pressurized fluid is supplied to the undervane portion of the vane elements so as to balance the forces imparted thereon. In a preferred embodiment, the vane pump includes a pump housing, a cam member, a cylindrical rotor member and a chamber. The pump housing has a cylindrical interior chamber formed therein and defines a central axis through which a vertical centerline and a horizontal centerline extend. The cam member is disposed within the interior chamber of the pump housing and has a bore extending therethrough. The bore defines a circumferential surface of a pumping cavity which includes a discharge arc segment, an inlet arc segment and seal arc segments separating the inlet arc segment and the discharge arc segment from one another.




A cylindrical rotor member is mounted for rotational movement within the bore of the cam member, about an axis aligned with the central axis of the interior chamber. The rotor member includes a central body portion which has a plurality of circumferentially spaced apart radially extending vane slots formed therein. Each vane slot supports a corresponding vane element mounted for radial movement therein. Each vane element has a radially outer tip surface adapted for slideably engaging the circumferential surface of the pumping cavity and a radially inner undervane portion within each vane slot.




A chamber is defined within the housing and is positioned for fluid communication with the undervane portion of each vane element and provides a desired pressure thereto. The chamber is in fluid communication with a first pressure source and a second pressure source. The first pressure source is associated with the discharge arc segment of the pumping cavity, and the second pressure source is associated with the inlet arc segment of the pumping cavity.




In a preferred embodiment of the subject invention, the vane pump is a variable displacement vane pump and the cam member is mounted for pivotal movement within the interior chamber of the pump housing about a fulcrum aligned with the vertical centerline of the interior chamber. Alternatively, the vane pump is a fixed displacement vane pump and the cam member is mounted within the pump housing and has a fixed relation with respect to the central axis.




It is envisioned that the circumferential surface of the pump cavity includes an inlet and a discharge arc segment having an arc length of about 150 degrees, and first and second seal arc segments having arc lengths of about 30 degrees However, as would be recognized by those skilled in the art, the arc length of the various segments can vary depending on factors such as the number of inlet and discharge ports and the shape of the circumferential portion of the pumping cavity.




It is further envisioned that in a preferred embodiment of the present invention, the first and second pressure sources are in fluid communication with the chamber each by way of a restrictor. Each restrictor is dimensioned and configured to limit an amount of fluid communicated to the chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the chamber. Also, the chamber is in fluid communication with the undervane portion of each vane element when each vane element passes through the seal arc segments as the rotor member rotates about the central axis.




It is presently preferred that each restrictor is dimensioned and configured to provide a pressure equal to one half of a pressure communicated thereto by the first or second pressure source. In one embodiment, each restrictor includes valve means for selectively controlling the volume of fluid communicated to the chamber by the first and second pressure sources respectively, resulting in the desired pressure within the chamber.




In a preferred embodiment, the vane pump of the present disclosure further includes first and second axially spaced apart end plates which are disposed within the interior chamber of the pump housing. Each end plate has a first surface which is adjacent to the rotor member and forms an axial end portion of the pumping cavity. Each end plate is spaced from the rotor member so as to allow frictionless rotation of the rotor member within the pumping cavity. In this embodiment, the first surface of the first end plate has the chamber and each restrictor is formed therein. Alternatively, and preferably, a chamber and corresponding restrictors can be formed in the first surface of both the first and second end plates. It is also envisioned that first and second channels are formed in the first surface of each end plate. The first channel is configured to provide a path for fluid to communicate from the first pressure source to the restrictor, and the second channel is configured to provide a path for fluid to communicate from the second pressure source to the restrictor.




It is further envisioned that the rotor member can include a plurality of substantially axial fluid passages machined in the central body portion thereof. Each passage is positioned between the plurality of circumferentially spaced apart radial vane slots and provides a path for fluid to communicate axially from the pumping cavity to the first and second end plate.




The present disclosure is also directed to a vane pump which includes a pump housing, a cam member, a cylindrical rotor member and means for providing a pressure to the undervane portions of the vane elements when each vane element rotates through the seal arc segments. Similar to the previously described embodiments, the pump housing has a cylindrical interior chamber which defines a central axis through which a vertical centerline and a horizontal centerline extend. The cam member is disposed within the interior chamber of the pump housing and has a bore extending therethrough. The bore defines a circumferential surface of a pumping cavity which includes a discharge arc segment, an inlet arc segment and seal arc segments separating the inlet arc segment and the discharge arc segment from one another. A cylindrical rotor member is mounted for rotational movement within the bore of the cam member, about an axis aligned with the central axis of the interior chamber. The rotor member includes a central body portion which has a plurality of circumferentially spaced apart radially extending vane slots formed therein, each vane slot supporting a corresponding vane element mounted for radial movement therein.




Unlike the previously described embodiments, this embodiment preferably includes a means for providing a pressure to the undervane portions of the vane elements when each vane element rotates through the seal arc segments. The pressure supplied to the undervane portion of the vane elements is a combination of a first pressure supplied from the discharge arc segment of the pumping cavity and a second pressure supplied from the inlet arc segment of the pumping cavity.




It is presently preferable that the means for providing a pressure to the undervane portions of each vane elements includes a chamber in fluid communication with the first and second pressure sources. Additionally, the first and second pressure sources are each in fluid communication with the chamber each by way of a restrictor. Each restrictor is dimensioned and configured to limit an amount of fluid communicated to the chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the chamber.




The subject application is also directed to a vane pump which includes a pump housing, a cam member, a cylindrical rotor member, first and second axially spaced apart end plates, and first and second pressure chambers.




In a preferred embodiment, the first pressure chamber is formed in the first surface of the first end plate and the second pressure chamber is formed in the first surface of the second end plate. Each chamber is positioned for fluid communication with the undervane portion of each vane element and provides a desired pressure thereto. Each chamber is in fluid communication with a first pressure source and a second pressure source, wherein the first pressure source is associated with the discharge arc segment of the pumping cavity, and the second pressure source is associated with the inlet arc segment of the pumping cavity.




According to the present invention, the pressures acting upon the vanes are balanced so that the vanes are lightly loaded or “floated” throughout the operation of the present pumps. This reduces wear on the vanes, permits the use of thicker, more durable vanes and, most importantly, provides elasto-hydrodynamic lubrication of the interface of the vane tips and the continuous cam surface. Such balancing is made possible by venting the undervane slot areas to an intermediate fluid pressure in the seal arc segments whereby, as each vane is rotated from the low pressure inlet segment to the high pressure discharge segment, and vice versa, the pressure in the undervane slot areas is automatically regulated to an intermediate pressure at the seal arc segments, whereby the undervane and overvane forces are balanced, which prevents the vane elements from being either urged against the cam surface with excessive force or from losing contact with the cam surface.




The regulation of the undervane pressure permits the use of thicker, more durable vanes by eliminating the unbalanced pressures which are found in the prior art. In the prior art, vanes were made thin to limit the loading of the vane against the cam, because relatively high discharge pressure produces the force that urges the vane tip against the cam, while relatively low inlet pressure acts to relieve the interface pressure between the tip and the cam. The small area of the thin vane allows tolerable loads at the vane tip but often requires dense brittle alloys and results in fragile vanes. Within the inlet arcs of the present invention the undervane areas are subjected to inlet pressure as are the overvane areas. Within the outlet arcs of the pump, the undervane areas are subjected to outlet pressure as are the overvane areas. Within the seal arcs of the pump, the undervane areas are subjected to a pressure that is midway between inlet and discharge pressure, to compensate for the overvane areas which are also subjected half to inlet and half to discharge. More importantly, the regulation of the undervane pressure and “floating” of the vanes causes the outer surfaces of the vanes to float over the continuous cam surface which is lubricated by the fluid being pumped, whereby metal-to-metal contact and wear are virtually eliminated. This overcomes the need for hard, brittle, wear-resistant, heavy metals, such as tungsten carbide, for the vanes and/or for the cam surface and permits the use of softer, more ductile, lightweight metals.




Those skilled in the art will readily appreciate that the disclosure of the subject application provides an improved vane pump configuration. The features discussed above and other unique features of the vane pump disclosed herein will become more readily apparent from the following description, the accompanying drawings and the appended claims.











BRIEF DESCRIPTION OF THE DRAWINGS




So that those having ordinary skill in the art to which the present application appertains will more readily understand how to make and use the same, reference may be had to the drawings wherein:





FIG. 1

is a cross-sectional view of a prior art variable displacement vane pump which includes a pump housing, a pivotal cam member, and a rotor member with associated vane elements;





FIG. 2

is a side elevational view in cross-section of the vane pump of

FIG. 1

illustrating the manner in which fluid is received into and discharged from the pumping chamber;





FIG. 3

is plan view of the face of an end plate of the vane pump of

FIGS. 1 and 2

, the face having a series of recesses formed therein for communicating fluid from either the high pressure and low pressure regions of the pumping cavity to the undervane portion of each vane element;





FIG. 4

is a cross-sectional view of a variable displacement vane pump constructed in accordance with a preferred embodiment of the present application, the vane pump including a pump housing, a pivotal cam member, and a rotor member with associated vane elements;





FIG. 5

is a side elevational view in cross-section of the vane pump of

FIG. 4

illustrating the drive mechanism for the pump and the axial opposed end plates disposed within the interior chamber of the pump housing and forming the ends of the pumping cavity;





FIG. 6

is a side view of the face of the end plate of

FIG. 5

illustrating a series of channels and recesses and two chambers formed in the face;





FIG. 7

is a partially exploded perspective view of the vane pump of

FIGS. 4 and 5

with parts separated for ease of illustration; and





FIG. 8

is a cross-sectional view of a rotor member constructed in accordance with a preferred embodiment of the present application.











These and other features of the vane pump of the present application will become more readily apparent to those having ordinary skill in the art form the following detailed description of the preferred embodiments.




DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS




Referring now to the drawings wherein like reference numerals identify similar structural aspects of the subject invention, there is illustrated in

FIG. 1

a prior art vane pump designated generally by reference numeral


10


. Vane pump


10


, which is similar to the pump disclosed in U.S. Pat. No. 5,545,014, includes a pump housing


12


defining an interior chamber which supports a cam member


14


and a rotor member


16


. Rotor member


16


includes a plurality of radially extending slots


17


. Each slot is configured to support a corresponding vane element


18


. Cam member


14


is mounted for pivotal movement about pivot pin


20


and defines a bore


22


forming a cam chamber. The cam chamber defines a cam surface


24


making continuous contact with the outer tip surfaces of the vane elements


18


.




Referring to

FIG. 2

, vane pump


10


further includes an inlet region


50


for admitting low pressure fluid into the pumping chamber and a discharge region


52


for discharging high pressure fluid from the pumping chamber. A main drive shaft


32


extends through the interior chamber of pump housing


12


along the longitudinal axis thereof for driving a central shaft member


34


. Shaft member


34


is supported for rotation by opposed journal bearings


36




a


and


36




b,


and is keyed to rotor member


16


for imparting rotational motion thereto.




As illustrated in

FIG. 1

, vane elements


18


fit snugly within slots


17


and function like pistons as they are depressed radially inwardly during movement of the rotor member through the discharge arc


62


(

FIG. 3

) of the pumping chamber. Each slot


17


has an radially inner undervane cavity defining an area that is open to inlet pressure when the vane element


18


is in the inlet arc region


60


(

FIG. 3

) of the pumping chamber, and to discharge pressure when the vane element


18


is in the discharge arc region


62


of the pumping chamber and the seal arc regions


64




a


and


64




b


(

FIG. 3

) of the pumping chamber. The manner in which pressurized fluid is communicated to the undervane cavity will be described in more detail herein below with respect to FIG.


3


.




With continuing reference to

FIG. 2

, opposed sideplates


40


and


42


, which are disposed within the interior chamber, form a sealed cavity between cam member


14


and rotor member


16


, and provide inlet and discharge ports for the cavity. Axial spacer


30


is supported within the housing


12


, between sideplates


40


and


42


, and has a thickness that is slightly greater than the thickness of cam member


14


. This allows the sideplates


40


and


42


to be tightly clamped against the spacer


30


by a plurality of threaded fasteners (not shown) while allowing small gaps to remain between the cam member


14


and the sideplates to reduce or eliminate friction therebetween.




Referring now to

FIG. 3

, surface


44


of side plate


40


is disposed adjacent rotor member


16


(not shown). The 360 degree pumping chamber includes an inlet arc region


60


, a discharge arc region


62


and sealing arc regions


64




a


and


64




b


positioned between the inlet and discharge arc regions


60


and


62


. The inlet arc region


60


represents the portion of the pumping chamber in which the volume contained between adjacent vane elements (i.e., within the buckets) increases and fluid is received into the pumping chamber. The discharge arc region


62


is the portion of the pumping chamber in which the volume contained between adjacent vane elements decreases. In the seal arc regions


64




a


and


64




b,


the volume remains substantially constant.




When the rotor


16


rotates within the pumping chamber, the centrifugal force created thereby imparts a radially outward force on each vane elements


18


. In addition, the pressurized fluid contained within adjacent buckets imparts a radially inward force on the adjacent vane elements. Often, the opposed forces which are applied to the vane elements


18


are not balanced. As a result, the vane tip of each vane


18


is either subjected to excessive wear due to a net radially outward force or fluid leaks from within the bucket due to a net radially inward force. This reduces pumping efficiency. An ideal situation occurs when the pressure applied to the vane elements is balanced and the vane elements “float” within the slots defined in the rotor. This condition results in minimum wear to the vane tips and minimizes the pressure losses caused by the lack of contact between the vane tips and the cam member.




With continuing reference to

FIG. 3

, pump


10


is adapted and configured to correct the unbalanced vane condition by applying pressure to the undervane portion of the vane. More specifically, pressure from within each bucket traversing the inlet region


60


is supplied to the undervane portion of vanes within the inlet arc region


60


. Similarly, the undervane portion of the vanes traversing the discharge arc region


62


is supplied with pressure from the buckets located in the discharge arc region


62


. The pressure, in the form of pressurized fluid, is supplied from the inlet arc region


60


and discharge arc region


62


by arcuate channels


66




i


and


66




d,


respectively. Channels


66




i


and


66




d


are formed in face


44


of endplate


40


and are in fluid communication with the inlet and discharge arc regions,


60


and


62


, respectively. Fluid from the inlet arc region


60


is received into chamber


66




i


and then flows radially inward through passages


68




a-e


to inner channel


69




i.


The passages


68




a-e


and the inner channel


69




i


are machined into face


44


of side plate


40


.




Inner channel


69




i


communicates with the undervane portion of each vane element


18


positioned within the inlet arc region


60


. In a similar manner, on the discharge side of the pumping chamber, fluid from within the discharge arc region


62


is received by arcuate channel


66




d.


The fluid then flows radially inward through passages


67




a-d


to inner channel


69




d.


As before, the passages


67




a-d


and the inner channel


69




d


are each machined into face


44


of side plate


40


. Arcuate channel


69


communicates with the undervane portion of each vane element


18


positioned within the discharge arc region


62


and the sealing arc regions


64




a


and


64




b.






The undervane pumping feature disclosed in

FIGS. 1 through 4

creates a balanced condition with the inlet and discharge arc regions


60


and


62


, but does not correct the unbalanced condition in the seal arc regions


64




a


and


64




b.


In the seal arc regions


64




a


and


64




b,


the net force on the vane


18


is radially outward. For example, when the vanes


18


are in the seal arc region


64




a,


the leading face of the vane is subjected to pressure from the discharge arc side


62


of the pumping chamber and the trailing face is subjected to pressure from the inlet arc side


60


of the pumping chamber. Therefore, supplying pressure from the discharge arc region


62


to the undervane portion of vane elements


18


which are traversing through the seal arc region


64




a


will not balance the forces imparted thereon. In fact, an interim pressure equal to half discharge pressure plus half inlet pressure is required to balance the forces.




Referring now to

FIGS. 4 through 8

which illustrate a vane pump constructed in accordance with a preferred embodiment of the present disclosure and designated generally by reference numeral


100


. It should be noted that similar structural elements to those previously described are identified by similar reference numerals. Vane pump


100


is a variable displacement vane pump having a cam member


114


mounted for pivotal movement within the interior chamber


113


of pump housing


112


about a fulcrum aligned with the vertical centerline


102


of the interior chamber


113


. As would be appreciated by those skilled in the art, the inventive aspects disclosed herein and applied to vane pump


100


can be applied to a fixed displacement vane pump in which the cam member is mounted within the pump housing and is fixed with respect to the central axis. Also, the inventive aspects disclosed herein can also be applied to variable or fixed displacement vane pumps which have multiple inlet or discharge regions and a plurality of seal arc regions.




Vane pump


100


includes a pump housing


112


, a cam member


114


, a cylindrical rotor member


116


and first and second chambers


180




a


and


180




b.


The pump housing


112


has a cylindrical interior chamber


113


formed therein and defines a central axis


106


through which a vertical centerline


102


and a horizontal centerline extend


104


. The cam member


114


is disposed within the interior chamber


113


of the pump housing


112


and has a bore extending therethrough. The bore defines a circumferential surface


124


of a pumping cavity which includes a discharge arc segment


162


, an inlet arc segment


160


and seal arc segments


164




a


and


164




b


separating the inlet arc segment


160


and the discharge arc segment


162


from one another.




A cylindrical rotor member


116


is mounted for rotational movement within the bore of the cam member


114


, about an axis aligned with the central axis


106


of the interior chamber


113


. As illustrated in

FIG. 8

, the rotor member


116


includes a central body portion


119


which has a plurality of circumferentially spaced apart radially extending vane slots


117


formed therein. Each vane slot


117


supports a corresponding vane element


118


mounted for radial movement therein. Each vane element has a radially outer tip surface


121


adapted for slideably engaging the circumferential surface


124


of the pumping cavity and a radially inner undervane portion


123


within each vane slot


117


.




Referring to

FIG. 5

, opposed end plates


140


and


142


, which are disposed within the interior chamber


113


, form a sealed cavity between cam member


114


and rotor member


116


, and provide inlet and discharge ports for the cavity. An axial spacer


130


, having a thickness that is slightly greater than the thickness of cam member


114


and is disposed between end plates


140


and


142


. This allows the end plates


140


and


142


to be tightly clamped against the spacer


130


by a plurality of threaded fasteners (not shown) while allowing small gaps to remain between the cam member


114


and the end plates to reduce or eliminate friction therebetween.




With reference to

FIG. 6

, the surface


144


of side plate


140


is disposed adjacent to rotor member


116


. As noted, the 360 degree pumping chamber includes an inlet arc region


160


, a discharge arc region


162


and sealing arc regions


164




a


and


164




b


positioned between the inlet and discharge arc regions


160


and


162


. The inlet arc region


160


represents the portion of the pumping chamber in which the volume contained between adjacent vane elements


118


or within the “buckets” increases and fluid is received into the pumping chamber. The discharge arc region


162


is the portion of the pumping chamber in which the volume contained in the buckets decreases. In the seal arc regions


164




a


and


164




b,


the volume remains substantially constant.




As discussed above with respect to

FIG. 3

, an ideal situation occurs when the pressure applied to the vane elements is balanced and the vane elements “float” within the slots defined in the rotor. This condition results in minimum wear to the vane tips and minimum pressure losses due to the lack of contact between the vane tips and the cam member. Vane pump


10


balanced the vanes in the inlet and discharge arc region


160


and


162


, but not in the seal arc regions


164




a


and


164




b.






Vane pump


100


as shown in

FIGS. 4 through 8

is configured in such a manner so that the forces imparted on each vane element


118


in all of the regions of the pump are balanced. When the vane elements


118


are in the inlet arc region


160


, the undervane portion


123


of each vane element


118


is supplied with pressurized fluid from the inlet arc region


160


. Similarly, the undervane portion


123


of each vane elements positioned in the discharge arc region


162


is supplied with pressurized fluid from the discharged arc region


162


.




The pressure is supplied from the inlet arc region


160


and discharge arc region


162


by arcuate channels


166




i


and


166




d


respectively. Channels


166




i


and


66




d


are formed in face


144


of endplate


140


and are in fluid communication with the inlet and dischrage arc regions,


160


and


162


respectively. Fluid from the inlet arc region


160


is received into chamber


166




i


and then proceeds to flow radially inward through passages


168




a-e


to inner channel


169




i,


the passages


168




a-e


and the inner channel


169




i


being machined into face


144


of endplate


140


. Inner channel


169




i


communicates with the undervane portion of each vane element


118


which is positioned within the inlet arc region


160


. In a similar manner, on the discharge side of the pumping chamber, fluid from within the discharge arc region


162


is received into arcuate chamber


166




d.


The fluid then flows radially inward through passages


167




a-d


to inner channel


169




d.


The passages


167




a-d


and the inner channel


169




d


are each machined into face


144


of endplate


140


. Arcuate channel


169




d


communicates with the undervane portion of each vane element


118


positioned within the discharge arc region


162


. One skilled in the art would readily appreciate that the quantity of channels and passages can be varied depending on the configuration of the pump and the associated operating pressures.




As illustrated most clearly in

FIG. 6

, chambers


180




a


and


180




b


are also defined in end plate


140


and are positioned for fluid communication with the undervane portion


123


of each vane element


118


when each vane element


118


is positioned within the seal arc regions


164




a


and


164




b.


Each chamber


180




a


and


180




b


is in fluid communication with a first pressure source and a second pressure source. The first pressure source is associated with the discharge arc region


162


of the pumping cavity, and the second pressure source is associated with the inlet arc region


160


of the pumping cavity.




As shown in

FIG. 6

, the arc length of the inlet and discharge arc segments


160


and


162


is about 150 degrees. The seal arc segments


164




a


and


164




b


have an arc length of about 30 degrees. The arc length of the various segments can vary depending on factors such as the number of inlet and discharge port and the shape of the surface pumping cavity.




With continuing reference to

FIG. 6

, the first and second pressure sources are in fluid communication with each chamber


180




a


and


180




b


by way of respective restrictors,


182




a-d.


Restrictors


182




a


and


182




c


are dimensioned and configured to limit an amount of fluid communicated to chamber


180




a


from the first and second pressure sources, respectively, thereby creating a desired pressure within chamber


180




a.


In a similar manner, restrictors


182




b


and


182




d


are dimensioned and configured to control the amount of fluid that is received into chamber


180




b


from the first and second pressure sources. As a result, the fluid pressure in chambers


180




a


and


180




b


is a selected combination of the fluid which is located in the inlet arc region


160


and the discharge arc region


162


. Therefore, the chambers


180




a


and


180




b


supply fluid having an interim or desired pressure to the undervane portion


123


of each vane element


118


when each vane element passes through the seal arc segments


164




a


and


164




b


as the rotor member


116


rotates about the central axis


106


.




In the embodiment illustrated in

FIG. 6

, each restrictor


182




a-d


is dimensioned and configured to provide a pressure equal to about one half of a pressure communicated thereto by the first or second pressure source. More specifically, the size of the passage which defines each restrictor is selected to allow the pressure in the corresponding chamber to be equal to the average of the sum of the pressures from the inlet and discharge arc regions


160


and


162


. This interim pressure applied to the undervane portion


123


of the vane elements


118


creates a balanced condition in the seal arc regions


164




a


and


164




b.






Referring to

FIG. 8

, rotor


116


includes a plurality of substantially axial fluid passages


184


machined in the central body portion


119


thereof Each passage


184


is positioned between the plurality of circumferentially spaced apart radial vane slots


117


and provides a path for fluid to flow from the pumping cavity to the channels


166




i


and


166




d


(see

FIG. 6

) formed in end plate


140


, or in both end plate


140


and


142


.




This feature is advantageous because fluid must travel radially inward from the bucket into each passage


184


, against the centrifugal force created by the rotation, so that the fluid is effectively filtered prior to entering each passage


184


. Moreover, particulate contained within the fluid in the pumping chamber is forced radially outward by the centrifugal motion, leaving particulate free fluid on the radially inner portion of the bucket.




While the invention has been described with respect to preferred embodiments, those skilled in the art will readily appreciate that various changes and/or modifications can be made to the invention without departing from the spirit or scope of the invention as defined by the appended claims.



Claims
  • 1. A vane pump comprising:a) a pump housing having a cylindrical interior chamber defining a central axis through which a vertical centerline and a horizontal centerline extend; b) a cam member disposed within the interior chamber of the pump housing and having a bore extending therethrough and defining a circumferential surface of a pumping cavity, the circumferential surface of the pumping cavity including a discharge arc segment of about 150 degrees, an inlet arc segment of about 150 degrees and seal arc segments of about 30 degrees separating the inlet arc segment and the discharge arc segment from one another; c) a cylindrical rotor member mounted for rotational movement within the bore of the cam member about an axis aligned with the central axis of the interior chamber, the rotor member having a central body portion which includes a plurality of circumferentially spaced apart radially extending vans slots formed therein, each vane slot supporting a corresponding vane element mounted for radial movement therein, each vane element having a radially outer tip surface adapted for slideably engaging the circumferential surface of the pumping cavity and a radially inner undervane portion within each vane slot; and d) a chamber defined within the housing and positioned for fluid communication with the undervane portion of each vane element and providing a desired pressure thereto, the chamber being in fluid communication with a first pressure source and a second pressure source, wherein the first pressure source is associated with the discharge arc segment of the pumping cavity, and the second pressure source is associated with the inlet arc segment of the pumping cavity.
  • 2. A vane pump as recited in claim 1, wherein the pump is a variable displacement vane pump and the cam member is mounted for pivotal movement within the interior chamber of the pump housing about a fulcrum aligned with the vertical centerline of the interior chamber.
  • 3. A vane pump as recited in claim 1, wherein the pump is a fixed displacement vane pump and the cam member is mounted with the pump housing and having a fixed relation with respect to the central axis.
  • 4. A vane pump as recited in claim 1, wherein the first and second pressure sources are in fluid communication with the chamber each by way of a restrictor, each restrictor dimensioned and configured to limit an amount of fluid communicated to the chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the chamber.
  • 5. A vane pump as recited in claim 4, wherein the chamber is in fluid communication with the undervane portion of each vane element when each vane element passes through the seal arc segments as the rotor member rotates about the central axis.
  • 6. A vane pump as recited in claim 5, wherein each restrictor is dimensioned and configured to provide a pressure equal to about one half of a pressure communicated thereto by the first or second pressure sources.
  • 7. A vane pump as recited in claim 4, wherein each restrictor includes valve means for selectively controlling the volume of fluid communicated to the chamber by the first and second pressure sources respectively, resulting in the desired pressure within the chamber.
  • 8. A vane pump as recited in claim 7, wherein the desired pressure is communicated to the undervane portion of each vane element when each vane element passes through the seal arc segment as the rotor member rotates about the central axis.
  • 9. A vane pump as recited in claim 1, further comprising first and second axially spaced apart end plates disposed within the interior chamber of the pump housing, each end plate having a first surface which is adjacent to the rotor member, each first surface forming an axial end portion of the pumping cavity, each end plate spaced from the rotor member so as to allow frictionless rotation of the rotor member within the pumping cavity.
  • 10. A vane pump as recited in claim 9, wherein the first and second pressure sources are in fluid communication with the chamber each by way of a restrictor, each restrictor dimensioned and configured to limit an amount of fluid communicated to the chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the chamber.
  • 11. A vane pump as recited in claim 10, wherein the first surface of the first end plate has the chamber and each restrictor formed therein.
  • 12. A vane pump as recited in claim 10, further comprising first and second channels are formed in the first surface of each end plate, the first channel being configured to provide a path for fluid to communicate from the first pressure source to the restrictor, and the second channel being configured to provide a path for fluid to flow from the second pressure source to the restrictor.
  • 13. A vane pump as recited in claim 12, wherein the rotor member further comprises a plurality of substantially axial fluid passages machined in the central body portion of the rotor, each passage positioned between the plurality of circumferentially spaced apart radial vane slots and providing a path for fluid to flow axially from the pumping cavity to the first and second end plate.
  • 14. A vane pump comprising:a) a pump housing hating a cylindrical interior chamber defining a central axis through which a vertical centerline and a horizontal centerline extend; b) a cam member disposed within the interior chamber of the pump housing and having a bore extending therethrough and defining a circumferential surface of a pumping cavity, the circumferential surface of the pumping cavity including a discharge arc segment, an inlet arc segment and seal arc segments separating the inlet arc segment and the discharge arc segment from one another; c) a cylindrical rotor member mounted for rotational movement within the bore of the cam member about an axis aligned with the central axis of the interior chamber, the rotor member having a central body portion which includes a plurality of circumferentially spaced apart radially extending vane slots formed therein, each vane slot supporting a corresponding vane element mounted for radial movement therein, each vane element having a radially outer tip surface adapted for slideably engaging the circumferential surface of the pumping cavity and a radially inner undervane portion within each vane slot; and d) means for providing a pressure to the undervane portions of the vane elements when each vane element rotates through the seal arc segments, the pressure comprising a first pressure supplied from a source within the discharge arc segment of the pumping cavity and a second pressure supplied from a source within the inlet arc segment of the pumping cavity, wherein the means includes a plurality of substantially axial fluid passages machined in the central body portion of the rotor, each passage positioned between the plurality of spaced apart radial vanes.
  • 15. A vane pump as recited in claim 14, wherein the pump is a variable displacement vane pump and the cam member is mounted for pivotal movement within the interior chamber of the pump housing about a fulcrum aligned with the vertical centerline of the interior chamber.
  • 16. A vane pump as recited in claim 14, wherein the pump is a fixed displacement vane pump and the cam member is mounted with the pump housing and having a fixed relation with respect to the central axis.
  • 17. A vane pump as recited in claim 14, wherein the circumferential portion of the pump cavity includes a discharge arc segment of about 150 degrees, a first seal arc segment of about 30 degrees, an inlet arc segment of about 150 degrees and a second seal arc segment of about 30 degrees.
  • 18. A vane pump as recited in claim 14, wherein the means for providing a pressure to the undervane portions of the vane elements comprises a chamber in fluid communication with the first and second pressure sources.
  • 19. A vane pump as recited in claim 18, wherein the first and second pressure sources are in fluid communication with the chamber each by way of a restrictor, each restrictor dimensioned and configured to limit an amount of fluid communicated to the chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the chamber.
  • 20. A vane pump as recited in claim 19, wherein the chamber is in fluid communication with the undervane portion of each vane element when each vane element passes through the seal arc segments as the rotor member rotates about the central axis.
  • 21. A vane pump as recited in claim 20, wherein each restrictor is dimensioned to provide a pressure equal to ½ of a pressure communicated thereto.
  • 22. A vane pump as recited in claim 19, wherein each restrictor includes valve means for selectively controlling the volume of fluid communicated to the chamber by the first and second pressure sources respectively, resulting in the desired pressure within the chamber.
  • 23. A vane pump as recited in claim 22, wherein the desired pressure is communicated to the undervane portion of each vane element when each vane element passes through the seal arc segment as the rotor member rotates about the central axis.
  • 24. A vane pump as recited in claim 14, further comprising first and second axially spaced apart end plates disposed within the interior chamber of the pump housing, each end plate having a first surface which is adjacent to the rotor member, each first surface forming an axial end portion of the pumping cavity, each end plate spaced from the rotor member so as to allow frictionless rotation of the rotor member within the pumping cavity.
  • 25. A vane pump as recited in claim 24, wherein the first and second pressure sources are in fluid communication with the chamber each by way of a restrictor, each restrictor dimensioned and configured to limit an amount of fluid communicated to the chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the chamber.
  • 26. A vane pump as recited in claim 25, wherein the first surface of the first end plate has the chamber and each restrictor formed therein.
  • 27. A vane pump as recited in claim 26, further comprising first and second channels are formed in the first surface of each end plate, the first channel being configured to provide a path for fluid to communicate from the first pressure source to the restrictor, and the second channel being configured to provide a path for fluid to communicate from the second pressure source to the restrictor.
  • 28. A vane pump comprisinga) a pump housing having a cylindrical interior chamber defining a central axis through which a vertical centerline and a horizontal centerline extend; b) a cam member disposed within the interior chamber of the pump housing and having a bore extending therethrough and defining a circumferential surface of a pumping cavity, the circumferential surface of the pumping cavity including a discharge arc segment, an inlet arc segment and seal arc segments separating the inlet arc segment and the discharge arc segment from one another; c) a cylindrical rotor member mounted for rotational movement within the bore of the cam member about an axis aligned with the central axis of the interior chamber, the rotor member having a central body portion which includes a plurality of circumferentially spaced apart radially extending vane slots formed therein, each vane slot supporting a corresponding vane element mounted for radial movement therein, each vane element having a radially outer tip surface adapted for slideably engaging the circumferential surface of the pumping cavity and a radially inner undervane portion within each vane slot; d) first and second axially spaced apart end plates disposed within the interior chamber of the pump housing, each end plate having a first surface which is adjacent to the rotor member, each first surface forming an axial end portion of the pumping cavity, each end plate spaced from the rotor member so as to allow frictionless rotation of the rotor member within the pumping cavity; and e) a first pressure chamber formed in the first surface of the first end plate and a second pressure chamber formed in the first surface of the second end plate, each pressure chamber positioned for fluid communication with the undervane portion of each vane element and providing a desired pressure thereto, each pressure chamber communicating with a first pressure source and a second pressure source through radially inner and radially outer arcuate channels formed in the first surface of each end plate, wherein the first pressure source is associated with the discharge arc segment of the pumping cavity, and the second pressure source is associated with the inlet arc segment of the pumping cavity.
  • 29. A vane pump as recited in claim 28, wherein the pump is a variable displacement vane pump and the cam member is mounted for pivotal movement within the interior chamber of the pump housing about a fulcrum aligned with the vertical centerline of the interior chamber.
  • 30. A vane pump as recited in claim 28, wherein the pump is a fixed displacement vane pump and the cam member is mounted with the pump housing and having a fixed relation with respect to the central axis.
  • 31. A vane pump as recited in claim 28, wherein the first and second pressure sources communicates with the first pressure chamber each by way of a restrictor, each restrictor dimensioned and configured to limit an amount of fluid communicated to the first pressure chamber from the first and second pressure sources respectively, thereby creating a desired pressure within the first pressure chamber.
  • 32. A vane pump as recited in claim 31, wherein the first and second pressure sources communicates with the second pressure chamber each by way of a restrictor, each restrictor dimensioned and configured to limit an amount of fluid communicated to the second pressure chamber from the first and second pressure sources respectively, thereby creating the desired pressure within the second pressure chamber.
  • 33. A vane pump as recited in claim 32, wherein each restrictor includes valve means for selectively controlling the volume of fluid communicated passing therethrough, resulting in the desired pressure within the first and second pressure chambers.
  • 34. A vane pump as recited in claim 28, wherein the first and second pressure chambers are in fluid communication with the undervane portion of each vane element when each vane element passes through the seal arc segments as the rotor member rotates about the central axis.
  • 35. A vane pump as recited in claim 32, wherein each restrictor is dimensioned to provide a pressure equal to ½ of a pressure communicated thereto.
  • 36. A vane pump as recited in claim 30, further comprising first and second channels are formed in the first surface of each end plate, the first channel being configured to provide a path for fluid to communicate from the first pressure source to the restrictor, and the second channel being configured to provide a path for fluid to communicate from the second pressure source to the restrictor.
  • 37. A vane pump as recited in claim 28, wherein the rotor member further comprises a plurality of substantially axial fluid passages machined in the central body portion of the rotor, each passage positioned between the plurality of circumferentially spaced apart radial vane slots and providing a path for fluid to communicate axially from the pumping cavity to the first and second end plates.
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 09/741,524, filed Dec. 20, 2000, now U.S. Pat. No. 6,375,435, and claims priority to U.S. Provisional Patent Application No. 60/236,294, filed Sep. 28, 2000, both of which are herein incorporated by reference in their entireties to the extent they are not inconsistent with this disclosure.

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Foreign Referenced Citations (1)
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445 487 Jun 1942 BE
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Entry
International Search Report dated Apr. 4, 2002.
U.S. Provisional patent application Ser. No. 60/236,294.
U.S. application Ser. No. 09/741,524.
Provisional Applications (1)
Number Date Country
60/236294 Sep 2000 US
Continuation in Parts (1)
Number Date Country
Parent 09/741524 Dec 2000 US
Child 09/966715 US