VANE PUMP
A vane pump having a pump containing a rotor driven via a drive shaft with the rotor having a number of generally radially extending grooves distributed over its circumference each of which grooves support a vane shaped delivery element in sliding fashion. The rotor is encompassed by an eccentric circumferential wall, against which the radially outer ends of the vanes rest. Housing end walls are situated adjacent to the rotor in the direction of its rotation axis. When the rotor turns, the vanes deliver medium from a suction region to a pressure region offset in the rotation direction. An annular groove is provided in at least one of the housing end walls which annular groove encompasses the rotation axis of the rotor, is situated opposite the inner regions delimited in the grooves of the rotor by the vanes, and is connected to the pressure region via a connecting groove in the housing end wall. The annular groove extends in eccentric fashion in relation to the rotation axis of the rotor.
The invention relates to a vane pump as generically defined by the preamble to claim 1.
A vane pump of this kind is known from DE 199 52 167 A1. This vane pump has a pump housing that contains a rotor, which is driven to rotate via a drive shaft. The rotor has a number of grooves distributed over its circumference that extend in an at least essentially radial direction in relation to the rotation axis of the rotor, each of which has a respective vane-shaped delivery element guided in it in sliding fashion. The pump housing has a circumference wall encompassing the rotor and extending eccentrically in relation to its rotation axis, against which the radially outer ends of the vanes rest. The pump housing has housing end walls situated adjacent to the rotor in the direction of the rotation axis of the rotor. Because of the eccentric arrangement of the circumference wall, the vanes form chambers, which expand and contract during rotation of the rotor and between which the medium to be supplied is conveyed with an increase in pressure from a suction region to a pressure region that is offset from it in the circumference direction. Centrifugal forces when the rotor is turning hold the vanes in contact with the circumference wall, but at low speeds, particularly when vane pump rotation is just starting, only slight centrifugal forces are exerted so that the vane pump only delivers a small amount. In the known vane pump, another delivery pump that forms a combined pump unit with the vane pump supplies the inner regions, which are delimited in the grooves by the vanes, with compressed medium, which presses the vanes outward toward the circumference wall in addition to the centrifugal force. In this case, at least one housing end wall is provided with an annular groove extending over part of the circumference of the rotor, which is supplied with compressed medium by the additional delivery pump. The annular groove is separated from the drive shaft by a sealing region in which the rotor and the adjoining housing end wall are situated spaced slightly apart from each other in the axial direction. The annular groove is situated concentric to the rotation axis of the rotor so that the sealing region has a constant radial span. The disadvantage in this known vane pump is that the annular groove extending over only part of the circumference of the rotor only exerts pressure on the inner regions of the grooves of the rotor over a corresponding part of a rotation of the rotor, as a result of which under some circumstances, there is only a slight pressing force of the vane against the circumference wall. Moreover, the sealing region can permit leakage of pressurized medium from the annular groove toward the drive shaft.
ADVANTAGES OF THE INVENTIONThe vane pump according to the invention, with the characteristics according to claim 1, has the advantage of the prior art that the exertion of pressure on the inner regions of the grooves of the rotor is intensified by means of the annular groove extending over the entire circumference of the rotor. In addition, by means of the eccentricity of the annular groove in relation to the rotation axis of the rotor the sealing region between the annular groove and the drive shaft, it is possible to intentionally enlarge the radial span of the sealing region in a circumference region of the rotor, which can be used to reduce the leakage from the annular groove.
Advantageous embodiments and modifications of the vane pump according to the invention are disclosed in the dependent claims.
An exemplary embodiment of the invention is shown in the drawings and will be explained in detail in the subsequent description.
As shown in
The inside of the circumference wall 18 of the pump housing 10 is situated eccentrically to the rotation axis 13 of the rotor 20, for example in the form of a circle or some other shape. In at least one housing end wall 14, 16, as shown in
In at least one housing end wall 14, 16, as shown in
The connecting groove 40 can, for example, extend inward from the pressure groove 34 in a radial direction or at an angle to a radius with regard to the rotation axis 13. The connecting groove 40 can, in particular, extend in such a way that it approaches the annular groove 38 in the rotation direction 21 of the rotor 20. In addition, the connecting groove 40 can extend in a spiral curve. The connecting groove 40 is preferably connected at one end at least approximately tangentially to the pressure groove 34 and/or at the other end, at least approximately tangentially to the annular groove 38. Preferably, the connecting groove 40 connects to the end region of the pressure groove 34 oriented opposite from the rotation direction 21 of the rotor 20. As a result of the connection of the annular groove 38 to the pressure groove 34, an increased pressure prevails in the annular groove 38 and therefore in the inner end regions of the grooves 24 of the rotor 20 with which it communicates, which increases the contact force with which the vanes 26 rest against the inside of the circumference wall 18, thus improving the delivery capacity of the vane pump. The curved course of the connecting groove 40 also generates a drag flow in it as the rotor 20 turns, resulting in a further pressure increase in the annular groove 38 and therefore in the grooves 24, thus further increasing the contact force of the vanes 26 against the circumference wall 18. In particular, this drag flow achieves a pressure increase in the annular groove 38 even when the vane pump rotation is just starting so that the vane pump delivers a sufficient quantity of fuel even as it is starting to turn. The curved course of the connecting groove 40 also assures that when the rotor 20 is turning, the vanes 26 move across the connecting groove 40 in an approximately tangential fashion, which minimizes the wear on the vanes 26 and the housing end wall 14, 16.
It is possible for the annular groove 38 and the connecting groove 40 that connects it to the pressure groove 34 to be provided in only one housing end wall 14 or 16 or for an annular groove 38 and a connecting groove 40 to be provided in both housing end walls 14 and 16, which grooves are then preferably situated in mirror-image fashion in relation to each other in the housing end walls 14 and 16. It is also possible for a respective annular groove 38 to be provided in each of the two housing end walls 14 and 16, but for a connecting groove 40 to be provided in only one housing part 14 or 16. It is also possible for the suction groove 30 and/or the pressure groove 34 to be provided in only one housing end wall 14 or 16, in which case the other housing end wall 16 or 14 is embodied as smooth or for a respective suction groove 30 and/or pressure groove 34 to be provided in each of the two housing end walls 14 and 16, which grooves are then preferably situated in mirror-image fashion in relation to each other in the housing end walls 14 and 16. In this case, however, the suction opening 28 and the pressure opening 32 are each provided in only one respective housing end wall 14 or 16, with the suction opening 28 provided in one housing end wall 14 and the pressure opening 32 provided in the other housing wall 16. With the mirror-image arrangement of the suction grooves 30 and pressure grooves 34 and of the annular grooves 38 and connecting grooves 40 in the two housing walls 14 and 16, the rotor 20 and the vanes 26 are loaded in at least approximately equal fashion at both ends in the axial direction so that little or no resulting force is exerted on the rotor 20 and the vanes 26 in the direction of the rotation axis 13. For example, the depth of the annular groove 38 and connecting groove 40 in the housing end wall 14, 16 is between 0.1 and 2 mm and the width of the grooves 38, 40 is preferably greater than their depth.
Claims
1-5. (canceled)
6. In a vane pump having a pump housing that contains a rotor driven to rotate via a drive shaft and which has a number of grooves distributed over its circumference that extend at least essentially in a radial direction in relation to the rotation axis of the rotor, each of which grooves has a respective vane-shaped delivery element guided in it in sliding fashion; having a circumferential wall of the pump housing encompassing the rotor and extending eccentrically in relation to its rotation axis, against which circumferential wall the radially outer ends of the delivery elements rest; having housing end walls of the pump housing that are situated adjacent to the rotor in the direction of its rotation axis, in which, when the rotor turns, the delivery elements deliver medium from a suction region to a pressure region offset from the suction region in the rotation direction of the rotor and an annular groove in at least one of the housing end walls in the suction region which annular groove extends over at least part of the circumference of the rotor and is situated opposite the inner regions delimited in the grooves of the rotor by the delivery elements, and a sealing region formed between the annular groove and the drive shaft, the improvement wherein the annular groove extends over the entire circumference of the rotor, is connected to the pressure region via a connecting groove in the housing end wall, and is embodied as eccentric in relation to the rotation axis of the rotor.
7. The vane pump according to claim 6, wherein the annular groove extends in an at least approximately circular fashion and its center point (M) is offset in relation to the rotation axis of the rotor toward a region of the circumferential wall of the pump housing situated between the suction region and the pressure region in the rotation direction of the rotor.
8. The vane pump according to claim 6, wherein in a circumferential region situated between the suction region and the pressure region in the rotation direction of the rotor, the annular groove is spaced a greater radial distance apart from the rotation axis of the rotor than in the opposite circumference region.
9. The vane pump according to claim 6, wherein the annular groove extends in such a way that it at least approximately follows the stroke of the vanes in the grooves of the rotor as the latter turns.
10. The vane pump according to claim 6, wherein the eccentricity of the annular groove is at least approximately of the same magnitude and oriented in the same direction as the eccentricity of the circumferential wall of the pump housing.
11. The vane pump according to claim 7, wherein the eccentricity of the annular groove is at least approximately of the same magnitude and oriented in the same direction as the eccentricity of the circumferential wall of the pump housing.
12. The vane pump according to claim 8, wherein the eccentricity of the annular groove is at least approximately of the same magnitude and oriented in the same direction as the eccentricity of the circumferential wall of the pump housing.
13. The vane pump according to claim 9, wherein the eccentricity of the annular groove is at least approximately of the same magnitude and oriented in the same direction as the eccentricity of the circumferential wall of the pump housing.
Type: Application
Filed: Nov 21, 2005
Publication Date: Sep 24, 2009
Inventor: Christian Langenbach (Affalterbach)
Application Number: 11/721,349
International Classification: F04C 2/344 (20060101); F04C 15/00 (20060101);