Vane pump having a shaftless balanced rotor

#The present invention relates to a vane pump for liquids, comprising a slotted rotor mounted in a stator, in which radially displaceable vanes are slidingly supported which can be pressed,while slidingly supported and while acted upon by centrifugal forces, spring forces or otherwise by compressive forces, against a stator inside wall, in the course of this delivery cells are formed which expand or narrow in a crescent-shaped fashion and the entry of the liquid takes place through a hollow concentric stator and the filling of the vane cells is effected from the inside to the outside.

#Vane pumps are constructed in the form of fixed displacement pumps or fixed displacement motors or in the form of variable displacement pumps or adjusting motors. However, vane pumps are likewise employed in the form of volumetric meters. The advantages of the vane pumps reside in their uniform delivery flow and in their quiet running. Problems do arise though due to the respective hydraulic radial and axial bearing loads.

#The hydraulic radial bearing loads in vane pumps possessing rotor lengths equal to the operating area of the vanes result from the product from the projection surface formed of rotor and projecting vane and the hydraulic pressure, i.e. the pressure differential acting upon the rotor. Lesser radial loads result from the friction of the vanes on the stator and in the rotor slots as well as from the dead weight of the rotor. In order to intercept the totally resulting radial forces and the powerful forces occurring already at small pressure differentials, the rotor shafts and supports are either dimensioned so as to be robust or it is attempted to provide an equalization by means of costly and--from a point of view of fluidics--disadvantageous multi-stroke pump or motor constructions.

#Embodiment examples of the invention are explained below with the aid of the drawings. Thus

#FIG. 1A shows a vertical section through a vane pump;

#FIG. 1B shows a vertical section through another embodiment of a vane pump;

#By preference the vane pump is constructed in the form of a single-stroke vane pump which, in the embodiment depicted in the FIGS. 1A, 1B, 2A, and 2B in the form of a pump, possesses a shaftless rotor 1 which, in the axial direction may either possess an external diameter 2 with a uniform circumference as in the vane operating area 15, or a circumference 3 reduced in contrast thereto. Outside the vane operating area, the rotor 1 is fitted into a stator 4 so as to be sealingly supported. Within this fitting-in area the stator possesses recesses 5 which, according to their position and size, are constructed in such a way that the operating pressure of the liquid acting herein results in a partial or complete hydraulic force balance also when taking the frictional and weight-related forces into consideration. In the embodiment illustrated in FIG. 2A, the recesses 5, when viewed in the axial direction, are disposed in front of or behind the vane operating area 15 and symmetrically thereto.

#The vertical front end areas or spacing differences 6 in diameter difference existing in the top half of FIG. 2A of the rotor 1 serve at the same time for the centering of the rotor whereby, in operation, on the front end, equal gaps 7 result between the rotor front end and the, in each case, oppositely located stator front end. In the rotors extended with reduced diameters that otherwise are axially freely movable, these diameter differences 6 serve to center the rotor relative to the operating space, in which connection the previously described disadvantage of the unilaterally greater effectiveness of the hydraulic pressure by bearing against the opposite side is acceptable since the front end area 6 in the form of an effective area is kept small by means of a slight difference in diameter. By means of this centering of the rotor relative to the operating space, between the front end areas of the rotor 1 and the stator 4 on both sides, the gaps 7 for a haydrostatic force compensation at the same pressure are ensured.

#The rotor 1 possesses slots 8, each of which proceeds radially, in which the vanes 9 are slidingly guided. The space in the guide slots 8 underneath the vanes 9 communicates in each case with the vane cell located behind the vanes in the direction of rotation, in the present case by means of radial recesses 10 on the vane and/or recesses 11 in the rotor. Since, in the inoperative state of the vane pump, as depicted in FIG. 3, the vanes 9 which, in operation, are moved outwardly by centrifugal force, can be immersed in the rotor and the freely movable rotor 1, whose diameter has not been reduced, may be displaced axially on one side against the front end of the stator 4, whereby, when the vane pump is started up, the vanes 9 are prevented from emerging, which may lead to as much as a wedging of the vanes on the stator inner wall in question, within the area of the vanes 9 that are not acted upon by differential pressure, the stator inner frame components 12 laterally delimiting the operating space are constructed in the direction towards the axis of rotation so as to be conical or slightly chamfered, thus expanding the working space. These conical or chamfered stator inner frame components 12A do extend on both sides insignificantly further than conforms with the axial mobility of the rotor 1 in the stator so that, with the start of rotation of the vane pump, the vanes emerging due to centrifugal force immediately bring about a centering of the rotor 1 relative to the operating space 15 and the same is retained in the case of lacking axial forces also without any additional friction on the vanes 9.