Rotary Pump or Motor with Improved Intake, Exhaust, Vane and Bearingless Sleeve Features

This U.S. Continuation Patent application claims priority to U.S. Utility patent application Ser. No. 17/822,546, filed Aug. 26, 2022, which claims priority to U.S. Provisional Patent Application No. 63/237,545, filed Aug. 27, 2021, the entire contents of which are incorporated herein by reference.

This invention related generally to positive displacement rotary pumps and motors and more particularly to the management of the intake fluid, the exhaust fluid, the construction and operation of vanes and the construction and operation of the inner sleeve against which the vanes run.

Positive displacement rotary pumps are designed to transport fluid by drawing in the fluid on a low-pressure suction side of the pump and expelling the fluid on a discharge side under higher pressure through relative movement of pumping elements of the pump. Positive displacement rotary engines are designed to intake high pressure fluid on an intake side of the engine to drive the rotor and output shaft and the fluid is expelled under lower pressure on the exhaust side.

One type of positive displacement pump is a so-called vane pump, which typically includes a rotor housed within a pump housing and supporting a series of moveable vanes. The rotor rotates about an axis that is eccentric relative to an inner ring surface of the housing and is closed at the sides by a pair of housing end plates. The geometries of the offset rotor and inner ring surface create a crescent-shaped space that is narrowest at a close point where the surfaces nearly touch. The space progressively widens away from the close point along a suction side of the pump before transitioning onto the discharge side where the space then progressively narrows as it moves toward the close point. A fluid intake suction port is provided on the suction side and is in communication with a portion the widening space, whereas a fluid discharge port is provided on the discharge side in communication with a portion of the narrowing space. The moveable vanes are caused to move outwardly and inwardly relative to the rotor during operation of the pump so as to maintain engagement with the eccentric inner ring surface. As the vanes sweep along the suction port, a fluid such as air, is caused to be drawn into the space and when the vanes move past the suction port a fixed amount of the fluid becomes captured in a series of chambers defined between adjacent pairs of the vanes which transport the fluid toward the discharge side of the pump. When the fluid progresses to the discharge side, the narrowing of the space between the rotor and inner wall causes the fluid trapped in the chambers to progressively increase in pressure before being expelled out of the pump through the discharge port.

There are also sliding vane motors in which high pressure fluid enters the housing and interacts with the expanding chambers of the vanes to drive the rotor and an output shaft coupled to the rotor.

There is a certain amount of friction associated with positive displacement vane pumps and motors that can lead to a buildup of heat in the parts, including the rotor, which may act as a heat sink due to its mass. This can lead to undesirable expansion of the rotor and potential binding of the moveable parts, if not properly managed. High friction also decreases the efficiency of pumps and motors.

The liner for of the pump housing make take the form of a ring. It is known for vane pumps to provide the inner ring as a stationary component, which is fixed to the housing in the form of an immovable liner. It is also known to support the liner of a vane pump with rolling elements or bearings so that the liner can rotate relative to the stationary housing during operation of the pump. Liners supported by rolling elements help reduce friction compared to fixed liners, but add several parts to the assembly and can be noisy.

Traditional vanes for rotary vane pumps are rigid plate-like elements that fit into radial slots of the rotor and slide in and out with rotation of the rotor to maintain contact with the housing sleeve at the tips of the vanes. Other vane types include hinged vanes, which swing in and out to maintain engagement with the liner. Both types have their limitations, as in each case, the vanes can allow a certain amount of high pressure fluid past the sealing point of the vane as it sweeps past the close point. Such leakage leads to a loss in efficiency of the pump.

According to one aspect, a positive displacement rotary vane pump includes a pump housing with a suction port on a suction side of the pump and a discharge port on a discharge side of the pump. The pump includes a pump housing and pumping elements which create chambers of increasing volume on the suction side and decreasing volume on the discharge side. The chambers of increasing volume draw in and capture fluid from the suction port and as the pumping elements rotate the captured fluid is transported to the discharge side and progressively pressurized as the chambers decrease in volume as they approach a close point of the pump. The discharge port communicates with a leading chamber on the discharge side having relatively high fluid pressure and at least one trailing chamber of relatively lower fluid pressure. The fluid intake is advantageously routed through openings in the rotor and then directed to the chambers of increasing volume. The fluid intake is typically at a temperature different than that of the rotor and by directing the flow path through the rotor a beneficial heat exchange effect is recognized. If the intake fluid is relatively cool, for example, the rotor can give up some of its heat to the fluid before passing into the chambers. This has the beneficial effect of cooling the rotor which may improve its performance. It has the beneficial effect also of scavenging heat from the rotor to pre-heat the fluid before entry into the expanding chamber, in the case of applications where expulsion of heated fluid from the pump is desirable.

Another feature comprises provision of an inner ring that lines the housing and is supported for rotation relative to both the housing and rotor. The rotational support of the liner ring is achieved without roller elements in the case of a pump (i.e., there are no roller ballers or needle bearings, etc.). Rather, there is a small clearance between the inner ring and housing in which an oil film is maintained under pressure. According to a further advantageous feature, a pocket is provided in the housing in the vicinity of the close point and oil is fed into this pocket under pressure to support the liner ring for rotation relative to the housing and rotor. According to still a further advantageous feature, the oil in the pocket is maintained at the same fluid pressure as the pressure of the fluid in the pumping chamber adjacent the close point such that the liner ring is pressure balanced and floats at the location of highest load. According to still a further feature, the oil is fed to the pocket under pressure without use of a separate pump or other means external or internal to the rotary pump. According to still a further feature, the oil fed to the pocket is derived from the lubricant source used to lubricate other moving parts of the rotary pump. In particular, the pumping effect of the oil supply to the pocket is achieved by directing the exhaust stream of the rotary pump into an oil sump to create a pressurized environment equal to the pressure of the fluid expelled at the close point. The pressure in the sump forces a small amount of the oil in the sump into the pocket though a supply passage linking the pocket to the sump. In this manner, the outer surface of the liner ring is supported by a film of oil under the same pressure as the fluid pressing against the inner surface of the liner and the liner is able to rotate without physical bearings and with small clearance for a smooth and quiet operation. According to a further advantageous feature, the desired pressure balance on the inner and outer sides of the ring liner can be tuned by adjusting the shape and size of the pocket to achieve more or less pressure on the outside of the ring countering the pressure on the inside.

According to a further advantageous feature, the vanes are configured as leaf vanes and they are provided in large number to reduce the loading on the vanes by sharing the load among many vanes. The numerous vanes also decrease the chances of high pressure escaping past the vanes from the high pressure side to the low pressure side of the pump or motor. The leaf vanes are very thin and have a hooked mounting end that fits in an undercut slots of the rotor for low-friction swinging between a folded position against the rotor and an outward position against the inner wall of the pump or motor. The light weight leaf vanes provide low inertia and low friction. The leaf vanes are arranged on the rotor to be very close to one another. Preferably, the length of a main body of the leaf vane that extends from the mounting portion is about equal to or greater than the spacing between leaf vanes. Even more preferably, especially in the application of a motor, the leaf vanes are close enough together that the main body portion of each leaf vane overlaps onto the main body portion of the adjacent leaf vane when in the folded condition.

In the case of a pump, the leaf vanes may include a bi-directional sealing feature that engages the inner wall to seal both ahead of the vane and behind the vane to expel pressurized fluid through the outlet ahead of the vane while sealing the leading edge of the vane against leakage from high pressure training fluid. According to one embodiment, the bi-directional sealing of the vanes is achieved by having a leaf vane or swing vane with a leading edge that seals against the liner ring and pushes fluid ahead of the leading surface of the vane. A secondary seal trails behind the primary seal and projects in the opposite direction. The secondary seal functions as a flapper-type valve by resisting the passage of high pressure trailing fluid beyond the secondary seal so that the primary seal is guarded from exposure to such trailing fluid. The secondary seal is flexible and projects toward the trailing chamber opposite the primary seal and when encountering the high pressure trailing fluid the secondary seal is caused to be pressed against the sealing liner ring, preventing the fluid from reaching the primary seal and thus passing to the intake expansion side of the pump.

The flow control valve make take different forms and may comprise, for example, one or more reed-type valves that overlie a discharge port in an end plate of the housing. As fluid pressure builds in each of the discharge chambers toward movement to the close point, the positive pressure on one the chamber side of the reed pushes the reed out of sealed contact and permits the fluid to pass into the outlet port. The reed valve (or portion thereof) associated with the one or more trailing discharge chambers remains closed to the extent the pressure on the discharge port side exceeds that of the pressure in the trailing chambers, thus precluding high pressure fluid from backing up into the trailing chambers. When the pressure in the trailing chambers builds to the point where it exceeds the pressure seen on the opposite discharge side of the reed valve, the reed valve is caused to open and let the fluid pass out of the trailing chamber.

Another form of a flow control valve may comprise individual valves fitted on the rotor and associated with each chamber. In the area between adjacent vanes (i.e., in each of the chambers), the rotor can include an outlet that communicates with the discharge port when the associated chamber is rotated to suction side of the pump. When the pressure builds in the chambers sufficiently high to overcome the closing force of the valve, the valve in such chamber opens and releases the pressurized fluid from that chamber. The valves in the other trailing chambers remained closed, so that no fluid from the leading chamber can back up into the trailing chambers, and only open when the pressure in the trailing chambers exceeds the outlet port chamber on the opposite side of the associated valve.

The flow control valve system thus retains all of the benefits of positive displacement rotary pumps while reducing or eliminating the inefficiencies associated with the backflow of high pressure fluid from the higher pressure leading chambers flowing into the trailing chambers. The valve system acts to seal each of the discharge chambers from any inflow of pressurized fluids from the discharge port. The valve(s) open only when the pressure in any given discharge port exceeds the closing force of the valve(s), attributed principally to the higher pressure fluid in the discharge chamber acting on the back of the valve(s) in the trailing chambers. In other words, the valve(s) are unidirectional or one-way in design and operation and prevent high pressure fluid that has been pumped out of a leading chamber from contacting the trailing chambers. The one-way valve(s) could be a reed valve, a flap valve, a ball valve or other types of valves that would achieve the intended purpose.

illustrates a positive displacement rotary pumpconstructed according to a first exemplary embodiment. The pumpof this embodiment is a sliding vane pump and includes a rotorhaving a plurality of radial slotsin which a corresponding plurality of vanesare supported. The pumpincludes a housinghaving an inner wallthat has an associated inner wall axis. The housingis closed at its opposite axial ends. As illustrated, the housingmay be closed at back end by a first end plate. The opposite front end of the housingmay be closed by a second end plateand an intervening valve plate.

The rotoris mounted on a shaftthat extends through an openingin the valve plateand which is supported for driven rotation about a rotor axis by external means, such as a motor or engine. The shaftis suitably supported by at least one and preferably both end plates with bearing(s). The rotormay extend through one of the end platesfor engagement by the driving mechanism. The rotorand vanesare disposed within the space defined by the inner walland end plates,and intervening valve plate. The axis of the rotor is offset eccentrically relative to the inner wall axis. Both the outer surface of the rotorand the inner wallof the housingare preferably cylindrical and with that of the rotorbeing smaller in diameter and axially offset but with their respective surfaces arranged very close together at a close pointof the pump. The geometries and offset placement define a crescent-shaped spacebetween the rotorand inner wallthat is near zero in clearance at the close pointand widest opposite the close point, as illustrated also in.

The pumpincludes a fluid inletthat communicates with a part-crescent-shaped inlet portof the valve plate. The pump further includes a fluid outletthat communicates with a fluid outlet portof the valve plate. The direction of rotation of the shaftin the illustrated pumpofis counterclockwise. With rotation of the rotor, the vanesare caused to slide outward in their slotsand engage and keep contact with the inner wallduring operation of the pump. As the vanes sweep by the elongated inlet port, a suction is created which draws fluid (such as air) into the pumpAs the vanes move past the inlet port, a fixed amount of air is trapped between the adjacent pair of vanesthat have just swept by, the plates,,, the rotorand inner wall. As the rotorcontinues to rotate, the entrapped fluid is transported by the moving chamber from the inlet or suction side of the pumpto the outlet or discharge side of the pump. One the discharge side, the crescent-shaped portion of the spaceis progressively diminishing in size as rotation moves toward the close point. The trapped fluid is pressurized as the chamberprogressively decreases in volume as it moves toward the close point. Successive one of the vanes passing by the inlet portentrap subsequent volumes of air in trailing chambers. It will be appreciated that the leading-most chamberat or near the close pointis smallest in volume and its fluid is under the highest pressure, whereas the one or more trailing chambershave trapped fluid that is under progressively less fluid pressure.

The chambers,on the discharge side of the pumpare in communication with the discharge port,. The discharge portis fitted with a control valvethat allows pressured fluid to escape from the chambers,into the outlet, but not to return. The discharge portis preferably segmented such that a plurality discrete openingsare a provided that are open to the discharge side of the space, but which are walled off from one another by intervening wall segments. The valveincludes a reedthat is secured to an outer surface of the valve plateand which overlies the plurality of openings. The reed may comprise a thin piece of metal. The reed is anchored at one end, preferably adjacent the leading end of the series of openingsof the discharge port. The inlet portis not fitted with a valve.

In operation, high pressure fluid from the leading chamberis expelled into the outletthrough corresponding ones of the openingsthat align with the rotational position of leading chamber. The reed valve operates as a one-way or unidirectional valve and allows the high pressure fluid to push the distal portion of the reedaway from sealing contact with the valve platein the region covering the corresponding openingsassociated with the leading chamber. Once expelled, the high pressure fluid from the leading chambercannot enter the one or more trailing chambers due to the presence of the one-way valve. Specifically, the pressure on the back side of the reed valve caused by the high pressure fluid expelled from the leading chamber keeps the reed tight and sealed against the valve platein the region of the openingsassociated with the position of the trailing chambers. Only when the fluid pressure in a trailing chamber(s)exceeds the pressure exerted on the backside of the reedin that area does the reeddeflect and allow the fluid to pass, and even then it is one-way so there is no opportunity for higher pressure fluid from the outlet side to enter the chambers during operation. In this way, the trailing chambersare not subject to counterforces exerted by backflow of higher pressurized fluid expelled from the leading chamberthat would otherwise occur if the control valvewere not present. Recognized benefits include reduced torque in driving the rotorand improved efficiency and performance of the pump.

The reed is preferably one-piece and extends across all of the openings. The openings are not all of the same size or volume and narrow in accordance with the dimension of the diminishing crescent-shaped spaceon the discharge side of the pump. The reedis preferable curved and is widest it is base and progressively narrows toward its free distal end.

The inner wallmay take the form of a rotatable element. In particular, the inner wallmay be provided as an inner surface of an inner raceof a bearingthat is mounted in the housing. Rolling elementssupport the inner race for rotation relative to both the housingand the rotor. While the vanesstill slide along the surface of the inner wall, the inner wallcan also rotate to reduce friction and increase the efficiency of the pump.

illustrates another embodiment of a positive displacement pumpin the form of a Gerotor pump. The same reference numerals are used to represent like parts, but are offset by 100. The pumpincludes inner and outer Gerotor gears,having n and n+1 teeth, respectively. The inner gear is fixed to a rotatable shaftand the axes of the inner and outer gears are offset to define a variable increasing and decreasing volume of space on a suction side and discharge side of the pump, respectively. The pumpincludes a housingwith an inner wallthat receives the outer surface of the outer gear. The inner wallmay comprise a bearingthat supports the outer gearfor rotation relative to the housing. The housinghas closed ends and includes at least one end plateand an intervening valve platethat may be the same as described above with respect to the pumpof the first embodiment, including the inlet and outlet ports,and a control valveat the outlet port. The outlet port may similarly be segmented as a plurality of successive and discrete openingswalled off from one another. The end platehas a fluid inletcommunicating with the inlet porton the suction side of the pumpand a fluid outletcommunicating with the outlet porton the discharge side of the pump.

In operation, the rotation of the inner Gerotor gearin the counterclockwise direction about the axis of the shaftdrives the outer gearand as the teeth of the gears roll and slide past one another fluid such as air on the suction side of the pumpis drawn in to the pumpand becomes trapped in chambers that progressively decrease in volume as the chambers progress toward the close point between the gears on the discharge side of the pump. As with the vane pump of the first embodiment, the fluid trapped in the leading chambernear the close pointis under the highest pressure and the fluid trapped in trailing chambersis under relatively lower pressure. The high pressure fluid is expelled on the discharge side through the outlet port. As with the vane pump above, the openingsassociated with the position of the leading chamberdirect the high pressure fluid out of the chamber, past the reed valveand onto the outlet. Once expelled, the fluid is not able to return and specifically is not able to backflow to the trailing chambers. The same principles, features and benefits associate with the vane pumpare realized by the Gerotor pumpwhen outfitted with the control valve.

illustrates an alternative vane pump embodiment. The same numbers are used to represent like features but are offset by 200. The pumpincludes a rotor, a housing, inner wall, closed ends including end plateand valve plate. The vanesin this case are wing vanes supported at their base ends by the rotorfor individual rotation relative to the rotor. Rather the sliding outward and inward to maintain engagement with the inner wall, the wings pivot outwardly and fold inwardly as necessary during movement through the suction and discharge sides of the pump.

The control valveincludes at least one openingprovided in the rotorbetween each pair of vanes(in other words, each chamber includes an opening) and a valveis provided with each openingto enable pressurized air to escape from the chamber into the outlet ports and outlet. The openingsmay comprise slots and the valvemay comprise floating cylinders which seat against edge surfaces of the slots to keep the chambers closed until the fluid pressure in the chambers exceeds the holding force provided by the cylinders. The cylinders may span the full width of the rotor or may extend part way. In operation, high pressure fluid in the leading chamber forces the cylinderof that chamber inward allowing the high pressure fluid to escape through the section of discrete openingsassociated with the position of the leading chamberand out of the pump. The valvesin the trailing chambersremain closed so long as the backside pressure on the cylindersexceeds the pressure in the trailing chambers. The slotsare larger than the cylinderssuch that there is room below the cylinder for the cylindersto move. The slotsare in communication with the discrete openingsand communicate fluid only so long as the associated cylinderis open. The same feature, principles and advantages apply to this embodiment as they do the others.

illustrate an alternative embodiment of a vane-type fluid pump, indicated generally at, and,A-C andA-D illustrate details of component parts of the pump, to be described in further detail below.

The pumpincludes a pump housing, including a pump body, a first end plateand a second opposite end plate. The pump housinghas an inner cavity formed by the pump body, and end plates,, in which a liner ringis supported for rotation relative to the housing about first axis A. A rotoris mounted on a shaftand supported within the liner ringfor rotation about a second axis Bthat is offset relative to the first axis A. The inner surfaceof the liner ringhas a diameter larger than that of the rotorand they are positioned at a close pointwith the outer surface of the rotorspaced from but nearly touching the inner surfaceof the liner ring. From the close point, a circumferentially extending crescent-shaped spaceis provided between the liner ringand the rotor. A fluid intake portis provided in at least one and preferably both end plates,in communication with the crescent-shaped spaceon an intake side of the pumpto introduce fluid into the space, while a fluid exhaust portcommunicates with the spaceon the exhaust side of the pumpto enable fluid under increased pressure to escape the space, enter a sump wellto pressurize the sump welland from there leave the pumpthrough an outlet.

The rotorcarries a plurality of vanes. The vanesare each supported at their baseend in a respective notchof the rotor. There are 18 vanesandnotchesin the illustrated embodiment. The vanesextend the width of the rotorand each is leaf-like in design, having a main portionprojecting from the baseto a primary sealing edge. The baseis bent in a v-shaped form so that the lead end can be received within the notchand hook beneath an undercut ledgeof the notch. The complimentary shapes of the v-shaped baseand notch enable the main portionto swing toward and away from the outer surface of the rotor. The main portionis slightly bent but is a little greater than the curvature of the rotor surface. The vanesare stiff, but flexible or resilient, such that the main portioncan be forced into conformance with the shape of the outer rotor surface when the vanesare swung inward and the free edge of the v-shaped baseengages the undercut ledgesuch that further inward movement requires bending of the main portion. The vanesmay also include a secondary portionthat commences at the primary seal edge and is angled back toward the baseso as to diverge outwardly from but overly the outer surface of the main portion. The secondary portionis preferably thinner than the main portion. The secondary portionmay have a thickness of 0.005-0.007 inches while the main portion may have a thickness of less than 0.1 inches and more preferably less than 0.05 inches, and still more preferably about 0.025 inches. The vanesmay be made of any of a number of materials, such as hardened bronze or other suitable metal, non-metal or composite. The thin, light veinsoffer low inertial and friction and serve to increase the efficiency of the assembly. The secondary portionacts as a secondary seal in the form of a flapper valve. Looking at, as the rotorrotates counterclockwise in a pumping direction and the primary seal edgeapproaches and then passes by the close point, pressure in the trailing chamber can act on the primary seal edgecausing it to lift away from the liner ringand allow high pressure fluid to pass beneath the primary seal edgeinto the low pressure side of the pump, resulting in a loss of efficiency. The secondary portionprevents this by laying down against the liner ring and extending toward the trailing chamber. Such trailing pressure now acts on the secondary portioninstead of the primary seal edgeand forces the secondary portion into sealed engagement with the liner ring surface. As such, the high pressure fluid is blocked by the secondary portionfrom leaking past the primary sealing edge.

The vanes, in a pump application, function on the intake side to create ever expanding volume chambers to draw fluid into the chambers through the intake port. The inlet for fluid into the pumpis provided in this embodiment by a series of air inletson the intake end plate. These air inletscommunicate with air channelsprovided in the rotorand separated from one another by spokesof the rotor. The passage of inlet air through the rotorallows for heat exchange between the air and rotor, with the relatively cool air being heated and the rotor cooled. The may have beneficial effect for both the rotor, which is cooled, and the air, which is heated. The air in the channels is routed to the fluid intake portsprovide on the inner faces of each of the end plates through a series of drilled intake ports, best shown in.

As in the previous embodiment of, as the vanesrotate past the intake portand continue on to the compression side of the pump, the chambers captured between adjacent vanes and the rotor and liner ring are caused to become progressively smaller in volume. When the pressure in a given chamber reaches a predetermined level, the associated valveof the chamber is forced open and the pressurized fluid enters the exhaust port. This continues along the length of the exhaust portuntil the leading vaneof a chamber past the close point, at which point expansion begins again. Pressurized fluid entering the exhaust portis directed into a drilled passagewhich is open atto the interior or sumpof the pump housing. This openingcan be seen at about 11:00 in. From there, the pressurized air makes it way counterclockwise around the housing passage through a series of linked drill passagesin the internal webbingof the pump housing body. An air outletis provided at a distance away from the openingand walled off from a direct shorter path by intervening solid web. This routing allows any oil present in the exhaust air an opportunity to deposit itself onto the websand passage wallsof the housing so as to in effect scrub the air stream of oil. The oil then falls to the bottom of the sumpand rejoins the level of oilalready maintained in the sumpfor lubricating the moving parts of the pump.

The oil film that supports the liner ringfor rotation without assistance from roller elements or bearings comes from the oilin the sump. As shown best in, the inner wall of the bodyis formed with an oil pocketwhich is present at the close point. The pocketis shown as generally rectangular in shape and set in from the axial edges of the body. The pocketextends from the close point in both directions, but preferably further on the compression side of the pump. There is a small openinginto the oil pocketwhich communicates with an oil supply tubeextending from the openingdown into the oil bathin the sumpbeneath the surface of the oil. As already described, the sumpis under pressure from the exhaust air equal to that of the pressure of the pressurized air escaping from the chambers of the vanesinto the discharge port. Consequently, the pressure above the oil bathforces an amount of oil to flow through the supply tubeand into the oil pocketsuch that the pressure backing the rotatable liner ringis comparable to the pressure acting on the inside of the ring, including in the highest pressure zone near the close point. Some of the oil in the pocketis permitted to squeeze out and surround the entirety of the ringas the ringrotates relative to the housing. Additional oil pocketsmay be provided in other regions away from the close point to hold oil and reduce hydrostatic drag that might otherwise result if the pocketswere not present. It is expected that each particular application may require fine tuning of the pocket size and placement to achieve the optimal balance of pressure distribution on the outer side of the liner ringto counter the pressure on the inner side so the ringrotates freely and quietly during operation.

illustrates a cross-section of a rotary vane motor assemblyaccording to a further embodiment. The motorincludes a housinghaving an inner cavitywith an inner walldisposed about a first central axis A. A rotoris disposed in the inner cavityand is rotatable about a second axis Athat is offset from the first axis Ato create a variable width space S between the rotorand the inner wall. The housingis provided with a fluid intake portthat communicates with an intake portion of the space S and a fluid exhaust portthat communicates with an exhaust portion of the space S.

The motorfurther includes a plurality of leaf vanes(which may also be referred to as wing vanes) that are carried by the rotorand moveable between an inward folded condition in which the vanesare swung inwardly toward the rotorand an outward position in which the vanesare swung outwardly from the rotor as needed to maintain engagement of distal endsof the vanes with the inner wallof the cavity. The leaf vanes define a plurality of chambersbetween adjacent vanes, the inner walland the rotorof increasing and decreasing volume during operation of the assembly.

The inner wallis preferably defined by the inner surface of a sleevethat is supported for rotation relative to the stationary body of the housingand the rotor. In other words, the sleeverotates relative to both the housingand the rotor. In the illustrated embodiment, the inner sleeveis supported for rotation relative to the housingby bearings.

The leaf vanesare preferably identically constructed. An embodiment of the leaf vaneis illustrated inwhere it is seen that it is sheet-like and spans the width of the rotor. The vaneseach have a mounting portion that connects them to the rotorand a sealing portion that engages the inner wall. The mounting portions preferably take the form of hook portionsat an inner end of the vanesand the sealing portions are provided by engaging portionsat the opposite outward free ends of the vanes. The hook portionsare preferably V-shaped and the free leg of the “V” engages the rotor. More specifically, the rotoris formed with a corresponding plurality of recesses or slotsthat are open to the outer perimeter of the rotorand also open to at least one and preferably both sides of the rotor. The recesses are also open to at least one and preferably both axial ends of the rotorand closed off when assembled by end plates of the housingto accommodate installation of the mounting portionsof the veinsif desired, rather than mounting the veins from the periphery of the rotor. The recessesare undercut to present a ledge, lip or latchwhich receive and engage the hook portionsof the vanesto support them for swinging movement toward and away from the rotor. The contact between the hook portionand latchis line contact, such that essentially no resistance is offered when the vanesare swung outwardly due to the minimal line contact engagement area. The recessis shaped to receive the V-shaped mounting portiondeeper into the recesswhen the vanesare swung progressively inward in use and offering little resistance to such inward swinging movement. Under positive fluid pressure, the mounting portionof the vanes seal against the engaging latch portionsof the rotor. The vaneshave a main body portionthat each extend from the mounting portionangled away from the direction of rotation. The main body portionsare very thin, ranging from 0.010 to 0.100 inches thick and may be made of metal such as stainless steel or brass or bronze, or may be of other materials depending on the pressures and temperatures seen in a given application. The main body portionshave a length that is greater than the spacing between adjacent vanes, lending to their being numerous vanesspaced such that they overlap one another when in the inwardly folded condition. In one embodiment, the vanesmay be spaced 10 degrees apart such that there are 36 vanes, but even more vanes may be present in an application having a larger rotor. The close spacing enables the load to be distributed among numerous vanesand in turn enables the vanesto be thin and offer low frictional resistance to rotation, and if leakage should occur in any one vane, there are subsequent vanes that can trap the leakage before it gets to the discharge port of the housing. When folded, the main body portionof a given vaneoverlaps the main body portionof the trailing vane, preferably by at least 30% and more preferably by about 50% or more.

The rotoris provided with a plurality of slotsthat are provided between adjacent pairs therecesses and vanes. The slotsare open at the peripheral surface of the rotorto the chambers defined between adjacent vanesand selectively communicate with the intakeand exhaustports of the housingdepending upon the rotational position of the slotduring operation. When aligned with the intake portthe slotsguide a fluid, such as pressurized steam, into the associated chambersbetween adjacent leaf vanes. The expansive force of the heated pressurized steam drives the leavesand rotorwhile the volume of the chambersincrease as they travel away from the intake portand reach the maximum volume at 180 degrees away (i.e., at 12 o'clock) from the close point, as illustrated in. The close pointis where the rotoris closest to the sleeveand the vanesin the close point region are folded and overlapping, as illustrated in. (i.e., at 6 o'clock) of the motor. The chambersand slotsopen to the exhaust portas they pass by the 1 o'clock position and remain open until just before entering the 6 o'clock close pointposition. The escaping fluid (e.g., pressurized steam) may still be under pressure and still contain heat energy and may be returned to a boiler or used for other purposes, such as subsequent in-line vane motors′,″ for example, that may be constructed the same or similar to motorbut may be smaller or larger in size and may contain fewer or more vanes, as illustrated schematically, for example, in. The overlapping of the vanespassing through the close pointposition helps assure that high pressure fluid at the intake portdoes not leak past the vanesand escape directly to the exhaust port. When at the close point. A fully folded veinoverlaps not only the mounting portionof the trailing vane, but also the recessand slotassociated with the trailing vane. As the overlapped veinspass the close point, they begin to unfold and are exposed again to the intake portto repeat the cycle.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically described while still being within the scope of the invention.