Abstract:
A vane machine comprises an inner rotor ( 28 ) and an outer rotor ( 51 ). A plurality of radially extending vane elements ( 32 ) separates first vane chambers ( 89 ) from one another. The van elements ( 32 ), with a radially inner end region ( 34 ), are accommodated in the inner rotor ( 28 ) in a radially displaceable manner and, with a radially outer end region ( 36 ), are accommodated in the outer rotor ( 51 ) in a pivotable manner. It is proposed that the radially inner end regions ( 34 ) of the vane elements ( 32 ) be accommodated in the inner rotor ( 28 ) at a fixed angle and that the outer rotor ( 51 ) comprise individual shoes ( 38 ) which are separate for each vane element ( 32 ) and in which the vane elements ( 32 ) are accommodated in a pivotable manner.

Description:
This application is the national stage of PCT/EP2006/009765 filed on Oct. 10, 2006. 
   BACKGROUND OF THE INVENTION 
   The invention relates to a vane machine, in particular a vane pump. 
   A vane pump with a ring-shaped inner rotor is known from DE 100 40 711 A1 and holds a number of vane elements extending radially to the outside, which are radially movable. The radially internal end areas of the vane elements rest upon a rotationally secure central part and the radially external end areas upon a rotationally secure outer ring. The rotor can be turned around a rotary axis which is displaced with respect to the center axis of the central part and the outer ring. Delivery cells, initially becoming larger and then smaller, are thereby formed between the vane elements when the rotor rotates. Due to the volume change of the delivery cells, fluid is initially suctioned into the delivery cells and then discharged. The end areas of the vane elements slide on the central part or on the outer ring. Such a vane pump can be manufactured easily and at low cost. 
   For increasing the efficiency, a vane machine in the form of a pendulum slide pump is known from DE 195 32 703 C1. The vane elements are thereby slidably held in an inner rotor and are held rotatably in a ring-shaped outer rotor. The rotary axis of the inner rotor is displaced with respect to the rotary axis of the outer rotor as a result of which delivery cells initially becoming larger and then smaller again, also form during operation. However, the pendulum slide pump known from DE 195 32 703 C1 is complex and its production is therefore expensive. 
   The task of this invention is to create a vane machine which has a high degree of efficiency and can at the same time be produced simply and at little cost. 
   SUMMARY OF THE INVENTION 
   This task is solved with a vane machine having the characteristics of the independent claim. 
   By basically holding the radially internal end areas of the vane elements in the inner rotor at fixed angles, very good sealing between the vane elements and the inner rotor is achieved, which improves the efficiency of the vane machine. Moreover, due to the omission of the pivoting option required for a pendulum slide machine, the manufacture of the vane machine according to the invention is simplified in this area which, in turn, lowers the production costs. 
   Due to the fact that the outer rotor comprises individual shoes for each vane element with which the vane elements are rotatably connected, good sealing between the outer rotor and the vane elements is also achieved in this area, further improving the degree of efficiency of the vane machine according to the invention. Moreover, an additional variable volume results between adjacent shoes during operation of the vane machine design according to the invention which also leads to improved efficiency. 
   In accordance with an advantageous design of the vane machine, the radially outer area of a vane element is fixed rotatably at its shoe and the shoe is positively driven in the circumferential direction. This avoids the need for a radially internal central element which again simplifies the design of the vane machine according to the invention. 
   The vane pump design is also simplified when it comprises a rotationally secure housing section arranged radially outside the shoes, against which the shoes glidingly rest during operation. Such a gliding cooperation between the shoes and the rotationally secure housing section allows for good sealing and can nevertheless be implemented at low cost. 
   A precise compulsory guiding with a simultaneous low frictional resistance, simple production and most of all simple installation can be realized when at least one edge area of a shoe is guided slidingly in a guideway. This can be, for example, a lateral notch or formed between an outer ring and a ring-shaped step of a lateral cover element. 
   Since the shoes provide a comparatively large sealing surface, sufficient sealing and thus good efficiency of the vane machine according to the invention is achieved even if a sliding bearing of the shoes—as mentioned above, for example—works dryly, i.e. without the use of additional lubricants or sealing compounds. This is especially advantageous when using the vane machine according to the invention as a vacuum pump or compressor, since this prevents contamination of the gas flow by such substances. 
   In order to minimize the dead volume within a delivery cell and thus optimize the efficiency of the vane machine according to the invention, it is suggested that the shoes extend so far in circumferential direction that the gap between adjacent shoes is nearly zero in every area of the vane machine in which the volume of the first delivery cells is minimal. 
   It is also advantageous when the vane machine comprises at least one second delivery cell which is formed between the radially internal end area of a vane element and the inner rotor. This delivery cell is of the type used for common piston pumps. This further improves the efficiency, since a larger overall delivery volume is available. 
   Adding to simplification of the vane machine design, the first and second delivering delivery cells and/or the first and second suctioning delivery cells can each be connected to each other via at least one channel. Moreover, this channel is advantageously available as a notch in a lateral cover element and runs at an angle with respect to a radius line which is larger than 0°, in particular larger than 45°. This prevents any interactions between a vane element and the channel. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     A preferential design example of this invention is explained in detail below with reference to the attached drawings. The drawings show the following: 
       FIG. 1  shows a plan view on a vane pump; 
       FIG. 2  shows a side view of the vane pump of  FIG. 1 ; 
       FIG. 3  shows a cut along the line III-III of  FIG. 2 ; 
       FIG. 4  shows a perspective representation of a pump module of the vane pump of  FIG. 1 ; 
       FIG. 5  shows a cut along the line V-V of  FIG. 2 ; 
       FIG. 6  shows a perspective view similar to  FIG. 3  into the interior of the pump module; 
       FIG. 7  shows a cut along the line VII-VII of  FIG. 2 ; 
       FIG. 8  shows a cut along the line VIII-VIII of  FIG. 1 ; and; 
       FIG. 9  shows a representation similar to  FIG. 7  of the vane pump in a different operating state. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In  FIGS. 1 to 9 , a vane pump has the reference numeral  10 . Note that, for reasons of clarity, not all reference numerals are entered in all subsequent figures. As shown especially in  FIG. 2 , the pump comprises a cylindrical housing  12  which consists of a pot-like part  12   a  and a frontal cover  12   b . A pump module  14  is arranged in the housing  12 . 
     FIG. 3  shows a cut III-III of  FIG. 2  through an area of a base  16  of the pot-like section  12   a  of the housing  12 . The base  16  has an inlet  18  and an outlet  20 , communicating with the kidney-shaped opening  22  or  24  on the interior of the base  16 . A drive shaft  26  is also mounted to the base  16  and penetrates the cover  12   b  of the housing  12  at its opposite end for connection to a corresponding drive equipment via a coupling (not shown). 
     FIGS. 6 and 7 , for example, also show that the drive shaft  26  is connected with a cylindrical inner rotor  28  which has several slots  30  extending radially, distributed about the circumference, which are, however, not all provided with a reference numeral for reasons of clarity. Each slot  30  holds a portion of a rectangular, plate-like vane element  32 , which can slide therein in a radial direction but at fixed angles relative to the inner rotor  28 . The radially internal end area  34  of a vane element  32 , which is held in the corresponding slot  30  of the vane element  32 , is straight whereas the radially external end area of a vane element  32  has an axle-like swelling  36  with a circular outer cross-sectional contour. The longitudinal axis of this swelling  36  runs parallel to the longitudinal axis of the drive shaft  26 . 
   The circularly thickened end area  36  of a vane element  32  is held in a shoe  38  in a complementary recess (without reference numeral). The vane element  32  and shoe  38  are thereby fixedly connected with each other in the radial direction (arrow R in  FIG. 7 ) and in the circumferential direction (arrow U in  FIG. 7 ), but the vane element  38  can pivot relative to the shoe  38  within a certain angular range due to the positive connection. In this respect, the end swelling  36  on the vane element  32  forms a swivel axis. 
   The shoes  38  as well as the vane elements  32  are designed identically to each other, as ring-segment-like shell parts with a common center axis. They rest against a radially internal limiting wall of an outer ring  40  which is connected to the housing  12  in a rotationally secure fashion as described further below. 
   As shown especially in  FIG. 8 , the shoes  38 —seen in the direction of the drive shaft  26 —are longer than the vane elements  32 . They therefore, overlap the lateral rims  44  of the vane elements  32  with lateral edge areas  42   a  and  42   b . This overlapping of the lateral edge areas  42   a  and  42   b  provides compulsory guiding of the shoes  38  in a guideway  46   a / 46   b . The latter is formed by the outer ring  40  which, seen in the direction of the drive shaft  26 , is as long as the shoes  38 , and a ring-shaped step  48   a / 48   b  provided by the lateral cover elements  50   a  and  50   b , fixedly connected to the outer ring  40 . The two cover elements  50   a  and  50   b  thus form the frontal limitations of the pump module  14  (see also  FIG. 4 ). The shoes  38  form an outer rotor  51 . 
   The left ( FIG. 8 ) and front ( FIG. 4 ) cover element  50   a  has a suction kidney  52  and a pressure kidney  54  and a suction opening  56  located radially outside on a level with the shoes  38  as well as a corresponding pressure opening  58 . As shown in  FIG. 5 , additional notch-like and kidney-shaped openings  60  and  62  which are arranged on the inside of the cover element  50   a  facing the vane elements  32 , radially inward from the suction kidney  52 /pressure kidney  54  and approximately on a level with the radially internal area of the slots  30 . Note that the kidney-shaped opening  60  arranged in the area of the suction kidney  52  extends over a smaller area in the circumferential direction U than the kidney-shaped opening  62  arranged in the area of the pressure kidney  54 . 
   The internal kidney-shaped opening  60 , the suction kidney  52  and the suction opening  56  are connected fluidically with each other via notch-like channels  64  also disposed on the interior of the cover element  50   a  facing the vane elements  32 . Analogously, the kidney-shaped recess  62 , the pressure kidney  54  and the pressure opening  58  are connected with each other via corresponding notch-like channels  66 . The channels  64  and  66  run at an angle of approximately 45° with respect to the radius line R. 
   As shown especially in  FIGS. 4 and 7 , the unit formed by the outer ring  40  and the lateral cover elements  50   a  and  50   b —referenced with  68 —to which the shoes  38  and the vane elements  32  also belong due to the compulsory guiding in the guideway  46 , can be pivoted around an axis  70 . Towards this end, the outer ring  40  is connected with a bracket element  72  which is urged into the position shown in  FIG. 7  via a spring  74 . The center axis of the unit  68  is thereby not on the center axis of the drive shaft  26  but offset, parallel thereto. Due to the loading of a pressure region  76  with a fluid pressure, the bracket element  72  and thereby the unit  68  can be pivoted about the axis  70  in opposition to the tension of the spring  74  until the center axis of the unit  68  and the longitudinal axis of the drive shaft  26  are concentric. The bracket element  72  defines the sealing surfaces  78   a  and  78   b  which interact slidingly with the housing  12  for sealing the pressure region  76 . 
   The vane pump  10  works as follows, first of all regarding the position of the unit  68  shown in  FIG. 7 . When the drive shaft  26  rotates in the direction of the arrow  79 , the inner rotor  28  is also set into rotation. The vane elements  32  are thereby also carried along and with these also the shoes  38  which form the outer rotor  51 . Since, in the position of the unit  68  shown in  FIG. 7 , its center axis is offset compared to the rotary axis of the drive shaft  26 , first delivery cells  80  are formed between the outer ring  40 , shoes  38 , vane elements  32  and inner rotor  28 , the volume of which first increases on a suction side  81  and then decreases again on a pressure side  83 . 
   Due to the guiding of the vane elements  32  in the slots  30  and the positive holding of the swivel axis  36  of a vane element  32  in the recess in the shoe  38  complementary thereto, adjacent delivery cells  80  are well sealed with respect to each other. Due to the increasing volumes of the first delivery cells  80  on the suction side  81 , fluid is suctioned into the delivery cells  80  via the corresponding suction kidney  52 , the kidney-shaped opening  22  and the inlet  18 . As shown very clearly in  FIGS. 6 and 7 , the distances between adjacent shoes  38 —seen in the circumferential direction U—are also variable insofar as they also increase on the suction side  81  during rotation. An additional delivery volume  82  within the first delivery cells  80  is thereby achieved. 
   As shown in the same figures, a slot  30  between the radially internal end area  34  and the inner rotor  28  forms a second delivery cell  84  the volume of which also increases on the suction side  81  and decreases on the pressure side  83 . These delivery cells  84  are also filled with fluid on the suction side via the radially internal kidney-shaped opening  60 , the channels  64 , the suction kidney  52  and the kidney-shaped opening  22 . As the volume of the first delivery cells  80  and the second delivery cells  84  thereby decreases on the pressure side  83 , the fluid located therein is pressed via the pressure kidney  54  or the kidney-shaped opening  62  and the channels  66  to the kidney-shaped opening  24  and from there to the outlet  20 . The fluid volume  82  located between adjacent shoes  38  can also escape through the pressure opening  58  to the outlet  20 . As also shown very clearly in  FIGS. 6 and 7 , the extent of the shoes  38  in the circumferential direction U is selected in such a way that, in each area (reference numeral  86 ) of the vane pump  10  in which the volume of the first delivery cells  80  is minimal, the gap between adjacent shoes  38  is almost zero. 
   As already stated above, the shoes  38  with their radial outside interact slidingly with the inner wall of the outer ring  40 . Due to the comparatively large sealing surface, a good sealing between adjacent first delivery cells  80  is maintained without the need of additional sealants, in particular, without lubricants. A reduction of the sliding friction between the shoes  38  and the outer ring  40  can be achieved with a corresponding choice of material. 
     FIG. 9  shows the vane pump  10  in a state in which the bracket element  72  is displaced against the tension of the spring  74  in such a way that the center axis of the unit  68  and the swivel axis of the drive shaft  26  are concentric. It can clearly be seen that, in this case, the first delivery cells  80  and the second delivery cells  84  do not change volume even in response to rotation of the drive axis  26 , so that the vane pump  10  does not deliver any fluid in this operating position.