VARIABLE DISPLACEMENT PUMPS AND VANE PUMP CONTROL SYSTEMS

TECHNICAL FIELD AND SUMMARY

The following disclosure relates to vane pumps used to pump liquids including fuels such as gasoline, oils, refrigerants, solvents and the like.

Vane pumps are particularly useful for pumping liquid, such as gasoline, from a storage tank to a vehicle. A vane pump works by rotating a solid cylindrical body called a rotor having vanes sticking out of it. The vanes sweep fluid from an input pushing the fluid out of the pump. To accomplish this, the rotor is positioned offset from the pump's main chamber center line. This offset position creates a crescent-shape space inside the chamber on one side of the rotor. The vanes are movably fitted in slots in the rotor so that when the rotor rotates, the vanes are pushed into the slot as that part of the rotor moves close to the chamber wall and extends out when that part of the rotor moves away from the chamber wall. As a consequence, the vanes maintain a seal against the wall of the chamber pumping fluid. While the rotor is located in this fixed offset position, the vanes pump fluid.

A problem occurs when the pump nozzle or other control shuts off the flow of fluid. For example, a gasoline nozzle includes a lever that when engaged opens, releasing fluid from the pump. When the handle is released, the nozzle closes, cutting off fluid flow. In the past when this happened, the motor did not stop rotating. This means fluid is still pumping inside the pump, but with the nozzle closed it has no place to go. To solve this problem, a bypass circuit was created so fluid that is no longer being ejected from the pump can recirculate back into the inlet. This circuit requires many parts and causes wear on the system. This also means the motor is running at full load which can build up excessive heat, be relatively noisy, and reduce its duty cycle. In addition, prior art pumps employ a pressure compensator to control the fluid pressure.

An illustrative embodiment of the present disclosure includes a new vane pump that does not continue pumping fluid after nozzle shut off nor uses a pressure compensator. The stator ring is movable from an offset pumping position to a non-offset non-pumping position upon nozzle shut-off. The motor still rotates the rotor, but there is no longer any pumping load. As a result, the motor runs cooler and quieter and the duty cycle moves from 30 minutes to continuous duty, since duty cycle length is a function of heat buildup. This new vane pump also no longer employs the pressure compensator to control fluid to move pistons on each side of the stator ring to control pump flow. Instead, only one piston is acted on by fluid where the other piston is acted on by a spring. The spring can be used to establish the fluid pressure of the pump. In further illustrative embodiments different size springs can be used to create different fluid pressures.

An illustrative embodiment of the present disclosure includes opposing pistons that act on the stator ring to move it between pumping and non-pumping positions. For example, a bias piston located on one side is illustratively spring-loaded to push the stator ring to the pumping (offset) position. When the nozzle is opened, the spring force keeps the stator ring in the pumping position. Conversely, when the nozzle is closed, the fluid pressure from the still pumping rotor is diverted to a pilot piston that is illustratively located opposite the bias piston. Diverted fluid directed towards this pilot piston builds up. Substantial pressure pushes the stator ring back against the spring pressure of the bias piston. This moves the stator ring so it is no longer offset relative to the rotor. Where the rotor and stator ring substantially share coincident axes, the rotor no longer pumps fluid even though it is rotating.

When the nozzle opens again, fluid releases because of the built-up back pressure. As this happens, the pressure of fluid against the pilot piston is reduced which means the opposing spring again pushes the bias piston against the stator ring. Because the fluid is now flowing out of the nozzle, there is no back pressure acting on the pilot piston. The spring force of the bias piston overtakes the force from the pilot piston.

Another illustrative embodiment of this disclosure reduces clearance between the stator ring and port plate to prevent fluid leaks. In one illustrative embodiment, the port plate and seal are positioned about the periphery of the stator ring to eliminate clearance between the stator ring and the port plate. Illustratively, the seal is a ring positioned about the stator ring and against the port plate. Further, a bias or spring can be placed between the stator ring and seal to create a bias force on the seal against the port plate. The bias from the spring continually eliminates clearance even when the stator ring is moving. In other words, the biased seal effectively seals the chamber through light pressure while still allowing movement of the stator ring. In a further illustrative embodiment, since the inside of the stator ring forms the inner surface of a pumping chamber against which vanes move to push the fluid, it can be useful to maintain a circular outer configuration as well. For this reason, the control ring can be made flush with the outside diameter of the stator ring.

Another illustrative embodiment of the present disclosure includes a vane pump which comprises a rotor, a plurality of vanes, first and second pistons, at least one fluid passageway, a spring, and an activator. The plurality of vanes adjustably extend from the rotor. The moveable stator ring encircles the rotor and is configured to affect fluid flow when located in offset and non-offset positions relative to the rotor. At least one of the vanes is configured to selectively engage the rotor when the stator ring is located in the offset position to move fluid engaging the vane. The first and second pistons oppose each other and are configured to act on the stator ring to move the stator between offset and non-offset positions relative to the rotor. At least one fluid passageway is in fluid communication with the first piston. The spring is configured to move the second piston. The activator is configured to selectively initiate or cease fluid flow from the vane pump. The spring is configured to move the second piston to move the stator ring to the offset position to create fluid flow by the vanes. The vane pump is configured such that selectively ceasing fluid flow by the activator causes fluid from a still moving rotor to divert to the at least one fluid passageway. The fluid also diverts to the first piston. The force from that fluid causes the first piston to engage and move the stator ring. This force is also strong enough to move the stator ring against the second piston and bias from the spring. The stator ring now moves to the non-offset position which ceases fluid pumping. The vane pump is also configured such that upon selectively initiating fluid flow by the activator again, force from the fluid in the at least one fluid passageway is relieved. This allows the bias from the spring to move the second piston against the stator ring, thereby moving the stator ring to the offset position to pump fluid.

The preceding and other illustrative embodiments may also comprise: the vane pump being configured such that upon selectively initiating fluid flow by the activator, back pressure from the fluid in the at least one fluid passageway flows; the offset position of the stator ring relative to the rotor pumps fluid while the rotor rotates and wherein the non-offset position of the stator ring relative to the rotor inhibits pumping fluid; the activator being a nozzle assembly including an opening to dispense fluid and a trigger to selectively initiate or cease fluid flow from the pump; the vane pump being configured to not recycle fluid when the nozzle assembly ceases fluid flow; the vane pump being configured such that when the nozzle assembly ceases fluid flow the rotor continues to rotate, but there is no longer any substantial pumping load allowing a motor employed to rotate the rotor to be continuous duty instead of having a time-dependent duty cycle; a seal disposed about the periphery of the stator ring; a spring that biases the seal disposed about the periphery of the stator ring; a port plate located adjacent the stator ring, wherein the spring biases the seal disposed about the periphery of the stator ring against the port plate; the stator ring being movable relative to the port plate; the rotor including a reservoir in fluid communication with pockets in the rotor so that fluid can enter and exit the pockets via the reservoir based upon movement of the vanes in the pockets; each of the pockets including a chamfer between it and the reservoir; a fluid recovery path along an outer periphery of the stator ring; the fluid recovery path being in fluid communication with an inlet on the pump that receives fluid; the fluid recovery path being configured to direct any leaked fluid back toward the inlet; a fluid recovery configured to direct fluid from a shaft seal pocket to an inlet; and the stator ring being selectively adjustable between offset and non-offset positions to affect the flow rate of any fluid being pumped.

Additional features and advantages of the vane pump will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrated embodiment exemplifying the best mode of carrying out the vane pump as presently perceived.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure will be described hereafter with reference to the attached drawings which are given as non-limiting examples only, in which:

FIG. 1 is a perspective view of a prior art fluid pump;

FIG. 2 is a perspective view demonstrating the use of the prior art fluid pump;

FIG. 3 is a cross-sectional end view of the prior art fluid pump;

FIGS. 4
a and b are circuit views demonstrating the operation of the prior art fluid pump;

FIG. 5 is a diagrammatic view of an illustrative embodiment of a new vane pump as an alternative to the bypass valve circuit of FIGS. 4a and b;

FIG. 6 is another diagrammatic view of the pump of FIG. 5;

FIGS. 7
a and b are schematic views demonstrating the operation of the pump according to the present disclosure in contrast to prior art pumps of FIGS. 4a and b;

FIG. 8 is an exploded view of an illustrative embodiment of a fluid pump according to the present disclosure;

FIGS. 9
a and b are ghosted end views of an illustrative embodiment of the fluid vane pump of the present disclosure;

FIGS. 10
a and b are additional ghosted end views of the fluid vane pump of the present disclosure;

FIG. 11 is another illustrative embodiment of a fluid vane pump according to the present disclosure;

FIG. 12 is a side view of a portion of a pump assembly according to an illustrative embodiment of the present disclosure;

FIG. 13 is a side cross-sectional view of a portion of a pump assembly according to an illustrative embodiment of the present disclosure;

FIG. 14 is an exploded view of a portion of the pump assembly according to an illustrative embodiment of the present disclosure;

FIG. 15 is a detailed side sectional view of the assembly of FIGS. 13 and 14;

FIG. 16 is a perspective wireframe view of a portion of the pump assembly according to an illustrative embodiment of the present disclosure;

FIG. 17 is a forward view of the interior of a pump assembly with the rotor position offset from the stator ring according to a present embodiment of the disclosure;

FIG. 18 is another forward view of the interior of the pump assembly of FIG. 17;

FIG. 19 is a forward view showing isolated detail of a stator ring and rotor portion of the vane pump assembly according to a present embodiment of the disclosure;

FIG. 20 is a perspective view of the stator ring and rotor of FIG. 19;

FIG. 21 is another forward view of the stator ring and rotor according to a present embodiment of the disclosure;

FIG. 22 is an exploded view of the stator ring, rotor, and vanes according to a present embodiment of the disclosure;

FIG. 23 is a perspective view of an illustrative embodiment of variable displacement pump housing according to a present embodiment of the disclosure;

FIG. 24 is a perspective, partial cutaway view of another illustrative embodiment of a pump housing, rotor, and stator ring;

FIG. 25 is a perspective view of a manifold assembly for a vane pump assembly according to a present embodiment of the disclosure; and

FIG. 26 is a side sectional view of a pump housing portion of a vane pump assembly according to a present embodiment of the disclosure.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the variable displacement pump and systems and such exemplification is not to be construed as limiting the scope of the variable displacement pump and systems in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

A perspective view of an illustrative prior art fluid vane pump is shown in FIG. 1. Pump 1 includes a motor body 2 and nozzle 4 connected together via hose 6. It is appreciated that pump I attaches to a fuel tank (not shown) via connector 8. Nozzle 4 is illustratively of the type conventionally used at gas stations. Other types of nozzles can be used and are within the scope of this disclosure. This type is described to assist orienting the reader to the present disclosure. Motor 2 turns pump 1 which draws fluid up from the tank and into hose 6 so when handle 10 is engaged, nozzle 4 is opened releasing fluid. Conversely, when the handle 10 is disengaged, the nozzle is shut off preventing any further fluid release. This process is common practice for anyone filling up their gas tank at a gas station.

The view in FIG. 2 shows a gas tank 14 being filled by nozzle 4 from pump 1 attached to a pickup truck 12. This view illustrates the utility of such pumps. Often vehicles, like tractors and combines, need to be refueled, but cannot be driven to a gas station. Rather, the gas station needs to come to the vehicle. Pickup truck 12 with fluid pump 1 installed thereon becomes a mobile fuel station for vehicle 16.

A cross-sectional view of prior art fluid pump 1 is shown in FIG. 3. Fluid 18 enters pump 1 in direction 20. A rotor 22 with radially-extending vanes 24 rotate within chamber 26. Vanes 24 are movably fitted within slots 28 so they can extend and retract from rotor 22, as shown. This is employed because of rotor 22's offset positioning. Vanes 24 are configured to follow surface 34 of chamber 32. Rotor 22's offset positioning creates a crescent-shape spacing 36 which assists in building pressure in fluid 18.

A portion of pump 1 illustratively includes bypass valve assembly 40 that allows fluid still being pumped by rotor 22 to circulate even when nozzle 6 is closed. The two views shown in FIGS. 4a and b are schematics of pump 1 which include bypass valve assembly 40. During the pumping operation, fluid from container 42 is drawn up through illustrative line 44 and into pump 1 via rotor 22 rotating in direction 46 in an offset position. Fluid pressure builds in crescent spacing 36 and exits through hose 6 and out nozzle 4. Bypass circuit 40 includes a valve assembly 48 that keeps the circuit closed while nozzle 4 is open.

Conversely, as shown in FIG. 4b, when nozzle 4 is closed, fluid in hose 6 can no longer escape. The problem here is pump 1 is still operating. In other words, regardless of the condition of nozzle 4, rotor 22 continues rotating in direction 46 pushing fluid into hose 6. This causes back pressure in the circuit. That back pressure is what acts on valve assembly 48 pushing it open and allowing fluid to flow through bypass circuit 40. This recirculates fluid pumping from crescent spacing 36. Recycling the fluid allows it to keep moving, since the rotor keeps spinning. Of course, the net affect of this is the motor is pumping the same volume of fluid while the nozzle is closed. This causes heat and substantial wear on the parts, as previously discussed.

An embodiment of a variable displacement fluid vane pump 100, such as that shown in the diagrammatic view of FIG. 5, offers an alternative to this bypass valve circuit discussed in FIGS. 4a and b. Pump 100 includes a rotor 102 with variably-extending vanes 104 fitted within slots 106, similar to rotor 22 and vanes 24 of pump 1. Rotor 102 is rotated via rod 108, similar to shaft 30 of pump 1. In contrast, however, rotor 102 and vanes 104 are fitted within a movable stator ring 110, rather than a static chamber such as chamber 32 of pump 1.

In this illustrative embodiment, stator ring 110 is movable between displacement and nondisplacement positions. In other words, stator ring 110 is movable with respect to rotor 102 so that fluid entering chamber 112 can be either pumped out or not. As shown in FIG. 5, for example, chamber 112 includes a crescent-shape space 114. An axis of rotation 116 of rotor 102 is offset from the axis 118 of stator ring 110. This familiar offset positioning allows fluid to be pumped out, as previously discussed with respect to the prior art. Also shown in FIG. 5 are bias piston 120 and pilot piston 122 that can act upon stator ring 110 to move it. Bias piston 120 includes an illustrative bias spring 124 that acts on it to move it in direction 126. It is this movement that displaces stator ring 110 inside pump 100 to create the crescent-shape space 114 necessary for pumping. In this position, fluid flows in from inlet 128 through passage 130 and is pumped from chamber 112 out through passage 132 and ultimately out of nozzle 134. As bias piston 120 maintains stator ring 110′s position with respect to rotor 102 as shown, fluid will continue pumping out through nozzle 134.

The diagrammatic view of pump 100 shown in FIG. 6 demonstrates the effect of nozzle 134 shutting off fluid flow from passage 132. Rather than the pump's motor recirculating fluid, as done in the prior art, rotor 102 pushes fluid through passage 132 and back pressure passage 140. As passage 140 is filling, fluid is acting on pilot piston 122 pushing it in direction 142. This force acts on stator ring 110 pushing it in direction 142 as well. This force overcomes the opposing bias force of spring 124, causing bias piston 120 to move in direction 142. The affect of this is the central axis 118 of stator ring 110 becomes coincident with the axis of rotation 116 of rod 108 and rotor 102. This alignment eliminates the offset positioning that creates crescent-shape space 114 necessary to build the pressure that moves the fluid. The result is rotor 102 spins but no fluid is pumped. A benefit of this is less resistance is applied to vanes 104 translating into less resistance on rotor 102 and ultimately on the motor. Consequently, the motor runs cooler and quieter, since fewer forces are acting upon it.

As shown in FIG. 6, fluid in passages 132 and 140 are maintained which continues to apply back pressure against pilot piston 122. This maintains the stator ring in the coincident nonfluid displacement position. When the nozzle 134 is reopened, back pressure holding pilot piston 122 is eased allowing spring 124 to again move piston 120 in direction 126. This pushes stator ring 110 back to its offset position with respect to axis 116, as shown in FIG. 5. Rotor 102 and vanes 104 continue the process of pumping fluid through passage 132. Any remaining fluid in passage 140 is not enough to overcome the bias force of spring 124.

In contrast to FIGS. 4a and b, the views of FIGS. 7a and b show how fluid from container 42 is drawn through passage 130 and into pump 100. As shown in FIG. 7a, for example, bias piston 120 is holding stator ring 110 offset to create the crescent-shape space 114 so fluid pressure can build and pump fluid into passage 132. With nozzle 4 in the open position, the fluid will simply be ejected. As shown in FIG. 7b, however, nozzle 4 is closed, which builds back pressure in passages 132 and 140. This building fluid acts on pilot piston 122 pushing stator ring 110 back against pilot piston 120, overcoming the spring force produced by spring 124 causing stator 110 to move co-axial with respect to rotor 102. Fluid is now simply being spun inside chamber 112 and not being pumped out to passage 132. As previously discussed, when in this no-flow condition, the motor and wear parts are operating more efficiently.

An exploded view of pump 100 is shown in FIG. 8. A manifold 150 is the fluid connection between passages 130 coming in illustratively from side 152 to passage 132 (see, also FIG. 7) coupling at bore 154 of side 156. In this illustrative embodiment, fasteners 158 are used to attach manifold 150 to pump housing 160. Bores 162, as illustratively shown therein, each receive a bolt 158 to secure the attachment. Housing 160 also includes cavity 164. A motor (not shown) couples to housing 160 for driving rotor 102.

Stator ring 110 fits in cavity 164 along with rotor 102 and vanes 104. In this illustrative embodiment, a shaft seal is configured to surround rod 108 (see FIGS. 5 and 6) for preventing fluid from escaping from housing 160. Bore 168 is disposed in flange 170 and configured to receive bias piston 120 and spring 124 and is capped with plug 172. Flange 174 with bore 176 is configured to receive pilot piston 122 and plug 178. Port plate 180 with slots 182 and 184 disposed therethrough is positioned between rotor 102 and manifold 150. Fluid drawn from passage 130 passes through slot 184 entering chamber 112 and stator ring 110 where it is subjected to vanes 104 generating pressure and ejected through passage 182 and out bore 154 of manifold 150.

Schematic ghost-end views of pumps 100 and 200 are shown in FIGS. 9a and b and 10a and b respectively. These views depict alternate embodiments of a vane pump. Pump 100, for example, shown in FIGS. 9a and b, has the ability to move stator ring 110 between a zero displacement condition (see FIG. 9a) and a full displacement condition (see in FIG. 9b). Zero displacement means fluid will not pump out through passage 132 because the stator ring and rotor have coincident axes of rotation. Full displacement, on the other hand, means the fluid is pumped through passage 132 at the maximum amount because stator ring 110 has been shifted to produce the maximum crescent-shape cavity 114 possible.

In contrast, pump 200, as shown in FIGS. 10a and b, has the ability to offer a calibrated displacement using an illustrative stator ring positioner 202 that engages pilot piston 122. Stator ring positioner 202 limits the movement of stator ring 110. In other words, stator ring positioner 202 prevents stator ring 110 from moving to a full displacement position, rather allowing incremental movement. This stator ring positioner 202 is illustratively adjustable allowing variable fluid flow control out of passage 132. In the illustrative embodiment shown, stator ring positioner 202 is a fastener attached to plug 178 via nut 208. The fastener either screws into or out of bore 176 to control or limit the amount pilot piston 122 and ultimately stator ring 110 can move. By drawing the fastener out of bore 176, stator ring 110 can be positioned to allow greater offset, resulting in greater fluid flow. Conversely, if the fastener is disposed further into bore 176, stator ring 110 creates less offset, resulting in lower pumping volume. It is appreciated that other mechanisms can be used to serve as a stator ring positioner, such as a pneumatic or hydraulically actuated positioner or an electrical servo-driven positioner.

The function of this disclosure is to provide a variable volume capability to the pump control scheme. The ability of the pump to achieve a settable, fractional, flow is facilitated by the fixed placement of the stator ring at a chosen incremental position somewhere between zero flow and full flow. Thus when the pump cycles from zero flow to “full” flow, what is actually obtained is some specific fraction or increment of full flow determined by the placement of the stator ring. As an illustration, a pump having a flow rate of 25 gallons per minute is used for re-fueling large off-road equipment. The pump is attached to a diesel storage tank that may be mounted on the back of a pickup truck that goes around the construction site once per week refueling the equipment. If each off-road vehicle has a fuel tank capacity of at least 150 gallons, the pump is able to refuel each vehicle in just a few minutes at a flow rate of 25 gallons per minute. If the truck is al so used to fuel smaller vehicles having relatively smaller tanks, a 25 gallon per minute flow rate is too fast. By the method and structures described above, the flow rate can be reduced accordingly.

An exploded view of another illustrative embodiment of a vane pump 280 is shown in FIG. 11. This illustrative embodiment includes pump housing 301 receiving stator ring 302 and rotor 303 with vanes 304 adjustably extending therefrom. A port plate 305 is positioned over rotor 303 and stator ring 302. Pilot piston 306 is capped via side cover plate 309. Bias piston 307 is acted upon by spring 310 and is capped using another cover plate 309. Manifold 308 is configured to attach to housing 301 to seal the unit using shaft seal 311 and o-ring 312.

Another embodiment of this present disclosure is directed to preventing leakage between a pump's port plate and stator ring. In an illustrative embodiment, variable displacement vane pumps, such as those previously described, use the movable stator ring to control fluid flow. Illustratively, the stator ring is movable between full and zero displacement to generate or stop fluid flow. In an embodiment, the maximum movement of the stator ring is equal to the pump rotor offset. In other words, moving the stator ring contributes to pumping fluid.

As previously discussed in other embodiments, fluid travels through slots in the port plate and deposits in a fluid chamber in the stator ring. Because the stator ring moves with respect to its adjacent port plate, a small amount of clearance exists between components which results in “pump slip.” This occurs when fluid slips passed the pumping components and out of the pumping chamber. Pump slip hinders the pump's efficiency, since a quantity of fluid entering the pump chamber inlet is not the same quantity exiting through the outlet.

An illustrative embodiment of this disclosure includes a stator ring and port plate with a seal positioned about the periphery of the stator ring. This eliminates the clearance between the stator ring and the port plate. In an illustrative embodiment, the seal is a ring positioned about the stator ring and against the port plate. Illustratively a bias or spring can be placed between the stator ring and seal. This creates a bias force on the seal ring against the port plate. The bias eliminates any clearance even while the stator ring is moving. In a further illustrative embodiment, since the inside of the stator ring forms the inner surface of a pumping chamber against which vanes move to push the fluid, it can be useful to maintain a circular outer configuration. For this reason, the control ring can be made flush with the outside diameter of the stator ring. It is appreciated that the seal can be used for any such vane pump that uses a stator ring to control volume.

A side view of a portion of pump assembly 400 is shown in FIG. 12. This view shows stator ring 402 and port plate 404. Stator ring 402 is similar to stator rings 110 and 302 of FIGS. 8 and 11, respectively. Similarly, port plate 404 is not unlike plates 180 or 305, as previously discussed. Because stator ring 402 is rotatable relative to plate 404, a clearance 406 may develop that could allow fluid entering chamber 408 (see FIGS. 13 and 14) of stator ring 402 to leak out causing the pump slip.

A side, cross-sectional view of assembly 400 is shown in FIG. 13. Contrast with FIG. 12, FIG. 13 shows stator ring 410 positioned adjacent port plate 404. This view also includes a seal ring 412 positioned in a notch 414 formed around the periphery of stator ring 410. Ring 412 is positioned against surface 416 of port plate 404. Springs 418 can also be positioned about notch 414 biasing against ring 412 to maintain contact with surface 416 of plate 404. As this view shows, clearance 406 is effectively eliminated. In this illustrative embodiment, outer periphery 420 is flush with the outer surface 422 of stator ring 410. This means seal ring 412 does not inhibit movement of stator ring 410.

An exploded view of assembly 400 is shown in FIG. 14. This view depicts an illustrative embodiment of port plate 404 with slots 430 and 432 disposed therein and is configured to receive fluid from an external source. Control ring 12 is shown having opening 436 disposed therein. Springs 418 are illustratively disposed in bores 438 in notch 414. It is appreciated that other types of springs can be used in place of the spring 418 shown, such as gas springs, wavy washers, or one large standard compression spring. In addition, the configuration of seal ring 412 is illustrative. Other shapes and cross-sections can be employed, so long as they prevent slip and do not inhibit movement of the stator ring 410 with respect to port plate 404.

A detailed side sectional view of assembly 400 is shown in FIG. 15. This view details how seal 412 fits within notch 414 with spring bias 418 pressing seal 412 against plate 404. This view shows how the outer periphery 420 of seal 412 is flush with the exterior of stator ring 410. This view also shows how the spring 418 keeps seal 412 pressed against plate 404 while stator ring 410 has freedom to move. This view further shows the lack of clearance between seal 412 and plate 404 preventing fluid from escaping out of a clearance 406. (See also FIG. 13.)

A perspective wireframe view of assembly 400 is shown in FIG. 16. Springs 418 push seal ring 412 from stator ring 410 to plate 404. This view also shows how slots 430 and 432 of plate 404 line up with opening 436 of seal 412. Aligning the openings allows stator ring 410 to move unencumbered by seal ring 412 while seal ring 412 maintains contact with port plate 404.

Another illustrative embodiment of this disclosure is directed to preventing vane detachment while pumping fluid. Vane detachment is a condition inside the pump where the vanes fail to fully extend from the rotor and engage the inner wall of the fluid chamber or stator ring.

As previously discussed, vane pumps work by rotating vanes that sweep fluid from an input out of the pump. The offset position of the rotor creates the crescent-shape space on one side of the chamber. The vanes are, therefore, pushed into a slot in the rotor as it rotates close to the chamber wall. Conversely, the vanes extend from the slot as the rotor rotates away from the chamber wall. Optimally, the vanes will maintain a seal against the wall of the chamber despite the rotor being located offset from the center line. Unfortunately, this does not always happen.

Sometimes, a vane fails to extend and fully contact the inner wall of the chamber or stator ring. In other words, there is no contact made between the end of the vane and the chamber wall while the vane is trying to push fluid out of the pump. This, called vane detachment, results in lower flow and pressure and creates overall pump inefficiency. Vane detachment may be caused by one or a combination of factors including, but not limited to, inadequate vane mass, improper tip speed or design, excessive cavitation, or fluid viscosity or evacuation rate from the vane pocket.

This present disclosure addresses vane detachment. The vanes, according to an illustrative embodiment, act similar to individual pistons. As the rotor turns through one revolution, each vane will slide from a retracted position to an extended position and then retract again. The vane will then repeat this cycle. As one vane is forced into its rotor slot, the vane located opposite will extend from its rotor slot. With the help of a reservoir between the slots, fluid can exit the slot of the retracting vane and fill the slot of the extending vane. Without the chamber, this process does not occur quickly enough. This may cause cavitation in fluid at the bottom of the vane pocket. Chamfers adjacent the slot help facilitate fluid flow between the reservoir and the pockets.

Because the fluid is not compressible when pumped into the reservoir on one side, the vane pockets on the opposite side (where the vanes are moving outward from pocket) are able to fill rapidly. This maintains a positive pressure against the vanes extending toward the chamber wall to create the desired seal between the two. In other embodiments, fluid is filling as rapidly as it is evacuating. The pressure in the bottom of the vane pocket is equal to the system pressure, thereby preventing cavitation. Vane detachment is also eliminated because of the constant pressures on the bottom of the vanes that are extended.

A forward view of the interior of a pump assembly 468 with rotor 472 positioned offset from stator ring 474 is shown in FIG. 17. In this offset position, when rotor 472 rotates, vanes 476 push fluid deposited into cavity 478 out of the pump. As previously discussed, as long as the ends 480 of vanes 476 engage the inner wall 482 of stator ring 474, it is possible for the pump to reach its maximum efficiency.

The view of assembly 468 shown in FIG. 18 is similar to that previously shown in FIG. 17. In this view both rotor 472 and stator ring 474 are positioned the same as shown in FIG. 17. A difference is that several of the vanes 476 shown in FIG. 18 do not extend far enough from slots 484, so their ends 480 engage surface 482 of stator ring 474. This creates a gap 486 between end 480 and surface 482. As rotor 472 rotates, vanes 476 simply paddle past some of the fluid, as indicated by reference numeral 488, rather than pushing it out of the pump. By pushing past the fluid, output is reduced, requiring more work to push fluid out, thereby reducing efficiency. Vanes 476 are not extending far enough out of slots 484 to engage surface 482.

A front view of assembly 470, including stator ring 474 similar to the prior embodiments, is shown in FIG. 19. This view, however, shows a different rotor 490. A reservoir 492 is formed in rotor 490 that is in communication with pockets 494 that receive vanes 476. In this illustrative embodiment, reservoir 492 is a recess size to receive a quantity of fluid being pumped to deposit among the several pockets 494 to help keep vane 476 against surface 482 of stator ring 474. A chamfer 500 is illustratively disposed in each pocket 494 to allow fluid communication between reservoir 492 and pocket 494. Now fluid in the reservoir can move between pockets such that when the vane is disposed farther into the pocket, fluid will be pushed out of that pocket and enter another pocket to assist extending another vane. Because the rotor is positioned eccentric with respect to the inner surface 482 of stator ring 474, when vane 476 approaches proximate to stator ring 474, the vane is pushed back into the pocket 494. When the rotor is positioned distal from surface 482, vane 476 is free to extend into cavity 478 until it engages surface 482. Fluid will enter its pocket 494 from reservoir 492 to assist biasing vane 476 toward surface 482. Again, as one vane retracts pushing out fluid, another vane extends by the force of that exiting fluid.

A perspective view of assembly 470 is shown in FIG. 20. This view shows stator ring 474 with reservoir 492 disposed in rotor 490 and in communication with pockets 494 via chamfer 500. Also shown are vanes 476 moving either into or out of pocket 494. When a vane is moving towards the center of the rotor, it pushes fluid out of the pocket and across the reservoir. An opposed vane pocket receives that fluid to assist pushing another vane out of pocket.

Another front view of assembly 470, as shown in FIG. 21, further illustrates how vane detachment is avoided. As rotor 490 rotates, in this case counterclockwise as indicated by directional arrow 510, fluid can enter reservoir 492, as indicated by directional arrow 512. And, as previously discussed, the fluid can enter pockets 494. As this view shows, however, active transfer of fluid from one pocket to another is what assists keeping the vanes against surface 482. Illustratively, vane 476.1 pushes towards the center of stator 490, as indicated by directional arrow 504. This reduces the available volume of chamber 494.1. Any fluid in that chamber in excess of the chamber's shrinking capacity will exit into reservoir 492 over chamfer 500.1. Because that volume of fluid is being displaced, it needs to move somewhere. As previously discussed, as one vane moves toward the center of the rotor, another vane is moving away creating space in that other pocket to receive fluid. For example, vane 476.2 can move out of pocket 494.2, as indicated by directional arrow 506. This increases the available volume in pocket 494.2 which can be filled with the fluid displaced from pocket 494.1. With fluid entering pocket 494.2 over chamfer 500.2, the fluid will tend to increase the volume in the pocket by applying a force against vane 476.2. In other words, the fluid is pushing vane 476.2 out of pocket 494.2 against surface 482 of stator ring 474. Vane 476.2 does not get literally pushed out of pocket 494.2. Rather, vane 476.2 exits pocket 494.2 up to the point it engages surface 482. The result is a firm seal between the vane and the stator ring surface. This process occurs with the other vanes as well. Vane 476.3 and its position with respect to stator ring 474 is shown pushing towards the center of rotor 490, as indicated by directional arrow 508. This pushes fluid into reservoir 492 and into pocket 494.4 (see reference numeral 514) and also pushes vane 476.4 against surface 482. Vane 476.5 similarly moves toward the center of stator 490 indicated by directional arrow 510, and similarly displaces fluid from pocket 494.5. As indicated in this view, the vanes located below line 512 push fluid out of the pockets and into the reservoir to make fluid available for the vanes being extended which are located above line 512. Furthermore, as illustratively seen in this view, there are more vanes contracting towards the center of rotor 490 than are being extended. This means that there are more vanes pumping fluid into the reservoir than there are vanes receiving fluid. This means that the force is directed towards the vanes receiving the fluid. It is appreciated that all of this is happening as rotor 490 is rotating in direction 510. The fluid exiting the pockets may fungibly mix before entering another pocket.

An exploded perspective view of assembly 470 is shown in FIG. 22. This view shows stator ring 474 with cavity 478 that receives rotor 490 with pockets 494 and reservoir 492. Chamfers 500 are also shown formed in pockets 494. Indeed, this view illustrates how the chamfers 500 facilitate fluid displacement between reservoir 492 and pockets 494. Vanes 476 are illustratively solid blocks sized to fit into pockets 494. Conventionally, for pumps that rely on centrifugal force or spring bias to move the vanes outward, slotted vanes are used. The slots allow fluid to evacuate the bottom of the pocket, when the vanes move into the pockets. Conversely, when the vane moves out, fluid enters the void left by the vane. According to the present illustrative embodiment, solid (i.e., non-slotted) vanes 476 are used. That way, fluid is forced into the bottom of the pocket and out into reservoir 492 when the vane moves further into the pocket 494. And, as previously discussed, that fluid is then available to enter into the void of another pocket.

Another illustrative embodiment of this present application addresses the issue of recovering fluid leaked from the stator ring because of the clearance between it and the port plate. (See, e.g. FIG. 12.) Recovering this leaked fluid assists in making the pump more efficient and generates less waste.

As previously discussed, a condition common to vane pumps, both fixed and variable displacement, is “pump slip.” In variable displacement pumps, fluid slips past the pumping components such as the rotor, vanes, and stator ring. In conventional pumps, fluid leaks by bypassing the control pistons, rotor, and vanes.

Pump slip can, nevertheless, be a double-edged sword. On one hand, it hinders overall pump efficiency, since it pumps less fluid out than what is going in. On the other hand, fluid that leaks from the stator ring or control pistons can be used to lubricate the components inside the pump. This reduces friction and heat buildup. In either case, leaked fluid from the pump must be accounted for. Vane pumps, both fixed and variable displacement for example, use a non-pressurized area, such as a case drain, to collect fluid. The drain is fluidly connected to a fluid reservoir via piping or hose. Pump slip in variable displacement pumps can also be problematic because too much fluid may accumulate around the stator ring. Because of this, a chamber is located around the stator ring connecting to the case drain to drain the fluid. Otherwise, too much fluid buildup around the stator ring may prevent the stator ring from moving causing the device to malfunction.

In the fluid recovery system of this present disclosure, the need for a case drain is eliminated by providing a series of fluid recovering paths located illustratively adjacent the stator ring chamber. Using the pump's negative suction pressure, the leaked fluid can be drawn out of the paths and then reenter the pump to be expelled.

Referring back to FIG. 12, an example of where fluid slip can occur is shown by clearance 406 between stator ring 402 and port plate 404. Because fluid passes from port plate 404 to stator ring 402, the fluid also leaks through clearance 406. This escaped fluid is not ejected out of the pump. Rather than allowing the fluid to collect in a drain, as shown further herein, the fluid will be drawn out of the stator ring chamber and recycled into the pump.

A perspective view of an illustrative embodiment of a variable displacement pump housing 600 is shown in FIG. 23. This view shows stator ring chamber 602 bound by chamber surface 604. This illustrative embodiment includes control piston ports 606. Facing 608 is configured to receive a manifold and port plate linking the fluid supply to the stator ring chamber.

Illustratively formed in the surface of stator ring chamber 602 are fluid recovery paths 610 and 612. In this embodiment, paths 610 and 612 are in fluid communication with a facing path 614. These paths are situated such that any fluid getting into the stator ring chamber 602 will be drawn into paths 610 and 612. As fluid collects in these pathways 610-614 it will then be drawn out of chamber 602 via negative suction pressure caused from the pump inlets through a fluid recovery groove in the port plate. (See also FIGS. 24 and 25.)

A perspective, partial cutaway view of another illustrative embodiment of a pump housing 620 is shown in FIG. 24. This view shows a stator ring 622 located in stator ring chamber 640 of housing 620. Rotor 624 includes vanes 626 movably located in pocket 628. This view shows the port plate removed but exposing a port plate chamber 629 positioned about the periphery of stator ring chamber 640. An o-ring groove 630 is also positioned about port plate chamber 629. Fluid recovery grooves 610, 612, and 614 are shown at the lower periphery of chamber 640. This view further shows the fluid behavior within the pump housing. As indicated by reference numerals 632, fluid is generally forced outward in a direction away from the center of rotor 624.

Because this fluid is directed outward, any clearance between components may result in fluid ending up between stator ring 622 and chamber surface 625. In this illustrative embodiment, a fluid recovery groove 636 is formed about the outer periphery of stator ring 622. Groove 636 offers space for fluid to accumulate and drain. The accumulated fluid is able to drain into slots 610, 612, and 614. Then, as previously discussed, negative suction pressure from the pump inlet draws the fluid out as indicated by directional arrows 638. The fluid exits stator ring chamber 640 and reenters the pump with other fluid between stator ring 622 and rotor 624.

A perspective view of a manifold assembly for a pump 650 is shown in FIG. 25. This view includes a manifold 652 with fluid inlet port 656 and outlet port 654 along with a manifold recovery slot 658. A port plate 660 has fluid inlet port 666 and outlet port 664 which line up with ports 654 and 656, respectively, to manifold 652. This allows fluid communication through the two structures. Port plate 660 also includes a fluid recovery slot 668 which is in communication with slot 658 of manifold 652. It is appreciated that face 662 of manifold 650 abuts face 672 of housing 620 (see, also, FIG. 24) with port plate 660 sandwiched inbetween. In this configuration, fluid collects in slots 610, 612, and 614 and exits through slots 658 and 668, as indicated by directional arrow 638. Once leaving the slots, this fluid joins the fluid being pumped through ports 654, 664, 656, and 666 entering stator ring cavity 678 (see, also, FIG. 24) to be pumped out.

Another illustrative embodiment of this disclosure provides a system integral to the pump and utilizing forces already present to recover any fluid that leaks past the shaft seal if it fails.

In the past when a shaft seal failed, fluid being pumped in the pumping chamber leaked past the seal and deposited in a weep hole adjacent the shaft seal pocket. The weep hole was open to the atmosphere so the fluid essentially leaked out of the pump in a controlled manner.

The present disclosure takes a different approach by recovering and reusing the leaked fluid. By utilizing the negative pressure created on the inlet of the pump, any fluid that leaks into the shaft seal pocket drains through an opening that leads back to the pump inlet. The leaked fluid then rejoins the other fluid being deposited into the pump.

A side sectional view of a pump housing 700 is shown in FIG. 26. Pumping chamber 702 shown therein is similar to chambers 602 and 629 of the prior embodiments. Shaft seal pocket 704 located adjacent pumping chamber 702 includes fluid recovery passages 706 and 708 leading to pump inlet 710. In an illustrative embodiment, an outlet plug 712 may selectively block an opening from passage 706. This allows fluid that might leak into pocket 704 to be selectively drained from the pump. Otherwise, negative pressure created at inlet 710 will draw any fluid leaked into pocket 704 into passages 706 and 708. The fluid is then reintroduced into chamber 702 to be pumped out.

Although the present disclosure has been described with reference to particular means, materials and embodiments, from the foregoing description one skilled in the art can easily ascertain the essential characteristics of the present disclosure and various changes and modifications may be made to adapt the various uses and characteristics without departing from the spirit and scope of the present invention as set forth in the following claims.

Number	Date	Country
61179888	May 2009	US
61287293	Dec 2009	US
61289066	Dec 2009	US
61292263	Jan 2010	US

VARIABLE DISPLACEMENT PUMPS AND VANE PUMP CONTROL SYSTEMS

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Provisional Applications (4)