Abstract:
A rotary vane pump or motor comprising a housing ( 16 ) with cylindrical inner peripheral wall defining a cavity, and a rotor ( 20 ) with cylindrical peripheral surface and a socket ( 41 ) internal to said peripheral surface, eccentrically disposed in the cavity. The rotor ( 20 ) is adapted to scroll the inner peripheral wall in close proximity thereto. The inner peripheral wall and the rotor surface define a working chamber between them. The housing ( 16 ) has a vane ( 22 ) with an end received within the socket ( 41 ) so as to enable the vane to slide in the socket maintaining predetermined degree of fluid tightness therebetween, and to enable the rotor ( 20 ) to orbit the cavity. The housing ( 16 ) has an inlet port ( 24 ) adjacent one side of the vane and an outlet port ( 26 ) adjacent the other side of the vane, both ports being open to the inner peripheral wall.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to vane pumps and motors and more particularly, to single-vane rotary pumps used for pumping of fluids in the chemical, medical and food industries, where the required process cleanliness necessitates frequent pump cleaning or replacement.  
       BACKGROUND OF THE INVENTION  
       [0002]     The single vane rotary pump/motor is known historically from attempts to build a steam engine with a rotary piston. Later the scheme was applied to compressors/pumps. (It is known in the art that, generally, a rotary piston engine (motor) is convertible into a pump if an external drive is provided, and vice-versa.) Thus, GB 926,495 discloses a rotary pump where the general layout includes a housing with a cylindrical cavity and a cylindrical piston (rotor) of lesser diameter eccentrically disposed therein. The pump drive, by means of an eccentric crank, causes the piston to orbit the cavity scrolling its inner peripheral wall. A pump chamber with crescent shape is thus defined between the piston and the housing. The piston has a radial projection (vane) accommodated in a recess of the housing, which divides the chamber into an expanding chamber and a contracting chamber. The pump further has an inlet port at one side of the vane, connected to the expanding chamber, and an outlet port at the other side of the vane, connected to the contracting chamber. In one embodiment, the vane has a cylindrical tip, while the recess is a radial channel with parallel walls contacting the cylindrical tip and allowing the vane to slide and swivel. In another embodiment, the vane and the recess have triangular shape.  
         [0003]     A few examples of single-vane pumps are provided in Japanese publication JP 06-200887. The pump has a single vane connected to the rotor and to the housing across the pump chamber. In one embodiment, the vane is slidably engaged to the housing while hinged to the rotor. In a second embodiment, the vane is, also slidably engaged to the housing—however, the vane is not joined to the rotor but is radially urged to the rotor by a spring in the sliding joint so that the vane is in sliding contact with the rotor. In a third embodiment, the vane is integral with the rotor, while sliding through a socket which in its turn is rotatably joined to the housing.  
         [0004]     In most embodiments, the outlet port is closed by a one-way check valve to prevent backflow of fluid, or pressure loss, when the scrolling zone of the rotor passes over the vane joint, since neither the vane, nor the rotor in that position isolate the inlet port from the outlet port of the pump.  
       SUMMARY OF THE INVENTION  
       [0005]     In accordance with the present invention, there is provided a rotary vane pump or motor comprising a housing with cylindrical inner peripheral wall defining a cavity, and a rotor with cylindrical peripheral surface and a socket internal to said peripheral surface, eccentrically disposed in the cavity. The rotor is adapted to scroll the inner peripheral wall in close proximity thereto. The inner peripheral wall and the rotor surface define a working chamber between them. The housing has a vane with an end received within the socket so as to enable the vane to slide in the socket maintaining predetermined degree of fluid tightness therebetween, and to enable the rotor to orbit the cavity. The housing has an inlet port adjacent one side of the vane and an outlet port adjacent the other side of the vane, both ports being open to the inner peripheral wall. The scroll zone of close proximity between the rotor surface and the inner peripheral wall of the housing, and the vane divide the working chamber into a first expanding inlet chamber in fluid communication with the inlet port and a second contracting outlet chamber in fluid communication with the outlet port.  
         [0006]     In one embodiment, the socket has parallel walls and the vane has a cylindrical tip received in the socket and providing fluid tightness together with the walls. The vane is rigidly attached to the housing but is thinner than its cylindrical tip, thus allowing for rocking motion within the socket.  
         [0007]     In another embodiment, the socket has an opening with two rounded lips receiving the vane therebetween and providing therewith the fluid tightness. The socket has a wider cavity behind the lips such that the vane is able to rock in the socket. The vane may have parallel walls providing, at variable angles of rocking, variable fluid tightness. Alternatively, the protrusions may be elastic, or vane thickness may vary along vane length, thereby providing, at variable angles of rocking, approximately uniform fluid tightness.  
         [0008]     In a further embodiment, the socket has an opening formed as a swivel cylindrical joint allowing sliding of the vane, of uniform thickness, through the joint and rocking of the vane together with the joint.  
         [0009]     In still further embodiments, the socket has parallel walls and the end of vane received in the socket matches the clearance between the parallel walls, but the vane is not rigidly attached to the housing. The vane may be attached to said housing by a hinge, or may be made flexible, so as to bend when the rotor orbits within the housing. Preferably, in the latter case, the parallel walls conjoin the peripheral surface along a smooth curve allowing the vane to bend smoothly.  
         [0010]     The inventive design affords two major advantages. The first is the ability to position the pump/motor inlet and outlet in closer proximity to each other, and thus reduce the rotational angle at which the rotor and cylinder are not in scrolling contact. The second advantage is that the rotor is balanced when exposed to fluid pressure, as the sealing between the vane and the rotor occurs at the rotor periphery.  
         [0011]     Thus the fluid pressure applies a force directed through the rotor center, resulting in negligible force between the vane and the rotor socket, as opposed to prior art rotors, where the protruding vane is exposed to pressure, which urges the vane against its socket, creating friction. (Note: This benefit does not apply to structure shown in  FIG. 6 ). An additional advantage of the vane extending inwards from the housing is the structural compactness obtained with pumps that employ long vanes.  
         [0012]     In accordance with an additional embodiment of the present invention, the rotary vane pump or motor comprises a sealing barrier disposed between the rotor periphery and the inner peripheral wall, preferably adjacent to the inlet port or to the outlet port. The barrier is adapted to prevent fluid communication between the inlet port and the outlet port when the scroll zone is over the inlet port or the outlet port or between them. Preferably, a second sealing barrier is disposed adjacent to the other port. The sealing barrier may be made of compliant material and attached to the inner peripheral wall or to the rotor periphery. Alternatively, it may be formed as cooperating teeth on the inner peripheral wall and on the rotor peripheral surface. The sealing barrier may be formed as an integral detail with the lips at the socket opening. Thereby, a single-vane pump or motor is provided, which does not require check-valves to function, but rather employs a barrier, to maintain separation between the pump or motor inlet and outlet.  
         [0013]     In accordance with another aspect of the present invention, the rotary vane pump is used in a pumping apparatus, coupled to a drive unit with an eccentric drive member adapted to drive the rotor. The pump is attachable to and detachable from the drive unit, the two units being constructed so that attaching the pump to the drive unit results in engagement of the rotor to the eccentric drive member. Preferably, the pumping apparatus includes attachment means allowing simple manipulation without tools.  
         [0014]     Preferably, the rotor has a concentric socket, the eccentric drive member comprises an eccentric crank adapted to fit rotatably, by a bearing, into the concentric socket when the pump is attached to the drive unit, and the housing has a sealed opening allowing the crank to enter the concentric socket. Preferably, the crank has a tapered head with such diameter and eccentricity that it can enter the concentric socket irrespective of the alignment between the socket and the crank before the attaching.  
         [0015]     The rotary vane pump is preferably made of materials suitable for its usage as a disposable unit, such as plastic.  
         [0016]     Thus, a pumping apparatus constructed of two main components is provided: a permanent drive unit, which contains all the costly components, and a low-cost disposable pump unit, which comes in contact with the pumped media, and is easily and quickly replaceable. The disposable pump unit contains all the pump parts which are subjected to high rate of wear or contamination, such that its replacement results in a complete pumping apparatus which is as good as new with respect to wear and cleanliness.  
         [0017]     The rotary vane pump of the present invention may further comprise a bypass channel, preferably integral with the housing, with an inlet in communication with the inlet port, an outlet in communication with the outlet port, and a one-way valve disposed between the inlet and the outlet so as to allow fluid flow bypassing said pump chamber, thereby improving flow uniformity, while the rotary vane pump is pulsating when pumping. The pump may further comprise a pulsation damper with an air chamber, connected to the outlet, adapted for damping the pressure ripple present at the rotary vane pump outlet.  
         [0018]     Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]     In order to understand the invention and its application, preferred embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:  
         [0020]      FIG. 1  is a schematic cross sectional view of a single vane pump in accordance with a preferred embodiment of the present invention, coupled with a pulsation damper and a by-pass valve;  
         [0021]      FIG. 2  is a schematic cross sectional view of the single vane pump of  FIG. 1 , with the rotor in registration with the vicinity of the fluid inlet and outlet ports.  
         [0022]      FIG. 3  is a cross sectional view of the single vane pump of  FIG. 1 , showing the attachment and coupling of the pump to the drive unit and the eccentric drive member;  
         [0023]      FIG. 4  is a cross sectional view of the single vane pump of  FIG. 3 , showing the disassembly and decoupling of the pump from the drive unit and the eccentric drive member;  
         [0024]      FIGS. 5 and 6  are cross sectional views of the single-vane pump in accordance with alternative embodiments of the present invention;  
         [0025]      FIG. 7  is a close-up of an embodiment where lips of the socket and a sealing barrier are integrated in one detail;  
         [0026]      FIG. 8  is an embodiment of the present invention with a hinged vane; and  
         [0027]      FIG. 9  is an embodiment of the present invention with a flexible vane. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0028]     With reference to  FIGS. 1 through 4 , there is shown a pumping apparatus  10  in accordance with a preferred embodiment of the present invention. The pumping apparatus  10  comprises a single vane pump  12  and a drive unit  14  detachably attached to each other.  
         [0029]     The pump  12  includes a housing  16  with a cylindrical cavity, and a cylindrical rotor  20  disposed eccentrically in the cavity of the housing so as to define a working chamber  18 . The housing  16  has an inlet port  24  and an outlet port  26  communicating with the working chamber  18 , and a radial vane  22  disposed between the ports  24  and  26 . Ports  24  and  26  are opened at the inner peripheral wall  28  of the working chamber. The housing  16  includes a bypass channel  29  with an inlet  30  in communication with the inlet port  24 , an outlet  32  in communication with the outlet port  26 , and a one-way valve  34  between the inlet and the outlet. Two sealing barriers  35  are disposed at the peripheral wall  28 , adjacent the inlet port  24 , and the outlet port  26 , respectively. The housing  16  has a central opening  36  at its wall  37  and a cover  38  closing the working chamber  18 .  
         [0030]     The rotor  20  is disposed in the housing cavity in sliding contact with the cover  38  and the wall  37 , sealing the opening  36  by means of a ring seal  40 . The rotor  20  has a radial socket  41  with two rounded lips  42  at its opening engaging the vane  22  so that it can slide within radial socket  41 . Lips  42  are at all times in contact with both sides of vane  22 , in a sealing fit. Vane  22  has varying thickness, for maintaining contact with both lips  42 , yet allowing for free movement of rotor  20 . Vane  22  and the socket  41  thus constitute a joint providing both sliding and rocking. Rotor  20  further has a central socket  44  facing the opening  36 .  
         [0031]     Drive unit  14  has a rotary shaft  50  with an eccentric crank  52  equipped with a bearing  54 . When pump  12  is attached to drive unit  14 , crank  52  is received by central socket  44  and shaft  50  is coaxial with the cylindrical cavity of the housing  16 .  
         [0032]     The radial geometrical relationship between drive unit  14 , eccentric crank  52 , rotor  20  and diameter of the cylinder pump chamber  18  is such that rotation of rotary shaft  50 , via the crank  52 , causes rotor  20  to scroll the inner peripheral wall  28 , maintaining contact or near-contact with the wall at scroll zone  56 . Due to the vane-and-socket joint of rotor  20  to the housing  16 , where rotor  20  is confined to vane  22  by means of vane socket  41 , the rotor performs simultaneously a reciprocating motion parallel to the vane socket, and a transverse rocking motion (an orbital motion).  
         [0033]     During this orbital motion, rotor  20  and housing  16  define two separate and variable volumes: an expanding inlet chamber  58  and a contracting outlet chamber  60 . Expanding chamber  58  is defined between the inlet side of the vane  22 , a portion of the peripheral wall  28  between the inlet port  24  and the scroll zone  56 , and an adjacent portion of the rotor&#39;s periphery. Contracting chamber  60  is defined between outlet side of the vane  22 , the remaining portion of the peripheral wall  28  between the outlet port  26  and the scroll zone  56 , and the remaining portion of the rotor&#39;s periphery.  
         [0034]     When the eccentric crank  52  rotates counterclockwise (see  FIG. 1 ), scroll zone  56  also travels counterclockwise, and expanding chamber  58  expands, thereby drawing or suctioning fluid from inlet  30 , through inlet port  24 . At the same time, contracting chamber  60  contracts, discharging the fluid through outlet port  26  to outlet  32 . In the position shown in  FIG. 2 , scroll zone  56  is in registration with vane  22  so that contracting chamber  60  has vanished while expanding chamber  58  has attained its maximal volume, after which it starts contracting and becomes the contracting chamber, while at the same time a “new” expanding chamber is born.  
         [0035]     In the position of  FIG. 2 , rotor  20  is in contact with the sealing barriers  35 , thereby sealing off possible communication between inlet port  24  and outlet port  26  around rotor  20 . Barriers  35  are made of elastic material, such as rubber, such that they are deflected by rotor  20  as it scrolls by them. In the absence of barriers  35 , when the rotor  20  is in the illustrated position, or rather in any position where scroll zone  56  is in registration with either inlet port  24  or outlet port  26 , or between them, pressurized fluid from outlet port  26  could flow around rotor  20  back to inlet port  24 . This undesirable reverse flow is traditionally prevented by use of a one-way valve at the outlet port. Sealing barriers  35  perform an equivalent function, preventing fluid back flow from the outlet port  26  to the inlet port  24 , without the negative effects, which valves introduce.  
         [0036]     Notably, fluid backflow may be prevented also by a single sealing barrier  35 . In such case, the single barrier should provide the sealing of a slightly wider gap. For example, if the left barrier in  FIG. 2  is removed, the remaining right barrier  35  must keep the gap between the rotor  20  and the inner wall  28  sealed until the scroll zone  56  reaches a point to the left of the inlet port  24 .  
         [0037]     It would be obvious to those skilled in the art that any barrier, suitably disposed between the rotor  20  and the inner peripheral wall  28 , may perform the function of blocking off the backflow path from outlet port  26  to inlet port  24 . For example, the barriers may be disposed on the rotor periphery opposite ports  24  and  26 , as shown in  FIG. 5 . Alternatively, a labyrinth barrier  43 , shown in the close-up of  FIG. 2 , may be formed as cooperating teeth on the inner peripheral wall and on the rotor peripheral surface.  
         [0038]     The bypass one-way valve  34  is optional. It is made of resilient material, such as rubber, which may deflect under pressure differential applied thereto, permitting fluid to flow from inlet  30  to outlet  32 . Thus, continuous flow of fluid may be maintained also at the time when expanding chamber  58  and contracting chamber  60  are not displacing fluid.  
         [0039]     In the illustrated preferred embodiment of  FIG. 1 , the single vane pump  10  is shown assembled with an additional pulsation damper  64  which in this embodiment is a trapped air reservoir with fluid outlet  66 . Damper  64  absorbs and dampens pressure ripple or fluctuations resultant from the cyclic nature of the fluid displacement in the single vane pump  10 . Trapped air  68  expands and contracts in response to pressure fluctuations of the fluid at outlet  32 , enhancing, together with by-pass valve  34 , stable and uniform flow and pressure of the pumped fluid at outlet  66 .  
         [0040]      FIG. 3  illustrates pump  12  of the pumping apparatus  10 , attached to the drive unit  14 , with the rotor  20  coupled to eccentric crank  52 , via bearing  54 . The pump is retained in place by wing nuts  70 , which are manually screwed and tightened on threaded studs  72  anchored in drive unit  14 . Drive unit  14  has a protrusion  74  mated to recess  76  in housing  16  such that pump  12  is keyed in proper relation to drive unit  14 .  
         [0041]      FIG. 4  illustrates pump  12  detached from drive unit  14 , with wing nuts  70  removed from threaded studs  72 . Cover  38  may be an integral part of pump  12  permanently attached to housing  16 , or it may be separate from housing  16 . In the illustrated embodiment, it functions both as a cover for the housing  16  as well as a retaining plate for retaining pump  12  engaged to drive unit  14 . It will be appreciated that there are other simple and fast means for manual attaching the pump to the drive unit, for example, a bayonet lock or a threaded collar.  
         [0042]     Eccentric crank  52  has a tapered head  78  facilitating the insertion of the crank  52  into the socket  44  of rotor  20 . The diameter of tapered head  78  and eccentricity of the crank  52  are selected so that tapered head  78  can enter into crank socket  44  while the pump is being attached to the drive unit, irrespective of the alignment of the socket  44  and crank  52 . For this purpose, the crank eccentricity is preferably less than one-fourth of the crank head diameter (the latter is presumed equal to the socket  44  diameter).  
         [0043]     The rotary vane pump of the present invention can be easily adapted for disposable use in the chemical, medical and food industries, where the required process cleanliness necessitates frequent pump cleaning or replacement. For this purpose, the pump is made of low-cost materials suitable for its usage as a disposable unit, such as plastic. The described structure of the vane-and-socket connection allows simple pump fabrication from molded components. Thus, the pump parts which come in contact with the pumped media are cheap and easily and quickly replaceable by a simple manipulation, without using any tools. The disposable pump unit advantageously contains all the pump parts that are subject to high rate of wear and contamination, while the permanent drive unit, including the eccentric crank with the bearing, contains all costly components. Thus, the replacement of the disposable pump unit results in a complete pumping apparatus which is as good as new with respect to wear and cleanliness.  
         [0044]     The vane-and-socket joint in the pump or motor of the present invention may be designed in a number of various ways, as shown in  FIGS. 5 and 6 . In an alternative embodiment of  FIG. 5 , the vane  22  is made flat, while socket  41  is equipped with swivel jaws  82  forming a swivel joint at the opening of the socket. Swivel jaws  82  form a channel of uniform width, mated to vane  22  so that the vane can slide across the swivel while rotor  20  orbits.  
         [0045]     As shown in  FIG. 6 , vane  22  may be made with an enlarged cylindrical tip  80 , while the vane socket  41  has parallel walls allowing sliding of tip  80  and rocking of rotor  20 .  
         [0046]     Although a description of specific embodiments has been presented, it is contemplated that various changes could be made without deviating from the scope of the present invention. For example, vane  22  in the embodiment shown in  FIG. 1  may be simplified to have parallel walls if a high degree of fluid tightness is not required. Alternatively, lips  42  may be made of elastic material. As shown in  FIG. 7 , the lips may be integrated in one detail  82  with the sealing barrier.  FIGS. 8 and 9  show other possible embodiments of the present invention—vane  84  with hinge  86 , and flexible vane  88  with rounded socket entrance  90 . Such vanes may be made only to slide in a narrow socket  91 , without rocking therein, for better fluid tightness. Accordingly, it is intended that the invention be limited only in terms of the appended claims.  
         [0047]     While the performance of the pump embodiment was described, the same embodiment will perform the motor function, when fluid pressure is applied at the inlet port, with lower pressure at the outlet port, applying torque to the rotor, which will result in the rotor&#39;s rotation.