Positive displacement pump, steering system and transmission

Abstract

The invention relates to a positive displacement pump, in particular a rotary vane pump for delivering a fluid for a consumer of a steering system, comprising a suction side and a pressure side. The positive displacement pump has at least one cam ring (2), a rotor (3), a drive shaft (4) with an axis of rotation (x), a plurality of vanes (5), a control plate (6a), an end plate (6b) and / or a cover (11). The lateral surface of the rotor (3) has slots which extend at least approximately radially over the width of the lateral surface and in which the vanes (5) are displaceably mounted, said vanes (5) being guided along the inner contour of the cam ring (2) when the rotor (3) is rotated. The control plate (6a), the end plate (6b), and / or the cover (11) contain a rear vane channel (9) which cooperates with rear vane compartments in order to press the vanes (5) against the cam ring (2), and the control plate (6a) and the end plate (6b) or the cover (11) enclose the cam ring (2) and the rotor (3) between one another in the axial direction. A respective sealing surface (10) is defined by the contact surface of one of the end faces of the rotor (3), said contact surface contacting the control plate (6a) and the end plate (6b) or the cover (11), and the sealing surface (10) extends in the radial direction over a sealing distance (10a), in particular between the drive shaft (4) and the rear vane channel (9). According to the invention, the sealing section (10a) of at least one of the sealing surfaces (10) increases in the direction from the suction side to the pressure side such that the sealing surface (10) is narrower at the transition from the pressure side to the suction side in the radial direction than at the transition from the suction side to the pressure side.

Description

[0001] Displacement pump, steering system and gearbox

[0002] The present application claims priority from German patent application No. 10 2024 1 13 712.6, the contents of which are incorporated herein in full by reference.

[0003] The invention relates to a positive displacement pump, in particular a vane pump for conveying a fluid for a consumer of a steering system, according to the preamble of claim 1.

[0004] The invention also relates to a steering system for a motor vehicle.

[0005] The invention further relates to a transmission for a motor vehicle.

[0006] Positive displacement pumps or vane pumps of the type mentioned above are known, for example, from DE 10 2005 050 216 A1 and DE 10 2009 000 155 A1.

[0007] In vane pumps, variable-sized pumping chambers are created by a plurality of movable vanes, which are arranged radially in a rotor. Assisted by hydraulic pressure, the vanes are pressed outwards against the inner contour of a cam ring as the rotor rotates. This hydraulic pressure is supplied to the vanes via an annular rear vane channel or arc-shaped partial rear vane channels, which are located in a control plate and / or an end plate or cover.

[0008] The control plate and the end plate or cover enclose the rotor axially between them. Arc-shaped surfaces or webs between the respective rear wing channel of the control plate and / or the end plate or cover and the drive shaft form a sealing surface or "contact surface" with the respective front face of the rotor. The contact between the respective front face of the rotor and the control plate and / or the end plate or cover via the respective sealing surface is not necessarily full-surface. Therefore, leakage can occur in the rear wing area across the width of the arc-shaped surfaces or webs.

[0009] DE 10 2008 042 728 A1 discloses an exemplary hydraulic system or steering system with a positive displacement pump designed as a vane pump.

[0010] Since the rear vane channels of positive displacement pumps or vane pumps are pressurized, the fluid or oil, especially in the case of high pressure or large pressure differentials, can unintentionally escape through the bridge between the rear vane channel and the drive shaft, leading to a reduction in the performance of the positive displacement pump and any steering system it may drive. This effect is exacerbated with increasing temperature, particularly due to the decreasing viscosity of the oil. The invention therefore aims to eliminate the aforementioned disadvantages and / or to improve known positive displacement pumps or vane pumps in the aforementioned sense. In particular, the invention aims to reduce internal leakage in order to improve power consumption and increase efficiency.

[0011] This problem is solved by a positive displacement pump with the features of claim 1.

[0012] The invention also aims to create a steering system for a motor vehicle with at least one consumer and a displacement pump, which is improved compared to the prior art.

[0013] This problem is solved by a steering system having the features of claim 9.

[0014] The invention also aims to create a transmission for a motor vehicle with at least one consumer and a displacement pump, which is improved compared to the prior art.

[0015] This problem is solved by a transmission having the features of claim 10.

[0016] The present invention provides a positive displacement pump, in particular a vane pump, for pumping a fluid for a consumer of a steering system, with a suction side and a pressure side, which has at least one cam ring, a rotor, a drive shaft with an axis of rotation, a plurality of vanes, a control plate, an end plate, and / or a cover. A cylindrical surface of the rotor has slots extending at least approximately radially across the width of the cylindrical surface, in which the vanes are slidably arranged, the vanes being guided along the inner contour of the cam ring during rotation of the rotor. The control plate, the end plate, and / or the cover contains a rear vane channel, which interacts with rear vane spaces to press the vanes against the cam ring. The control plate and the end plate or the cover enclose the cam ring and the rotor axially between them.A sealing surface is defined in each case by the contact surface of one of the end faces of the rotor with the control plate and with the end plate or the cover, wherein the sealing surface extends in the radial direction over a sealing section, in particular between the drive shaft and the rear wing channel.

[0017] According to the invention, the sealing area of ​​at least one of the sealing surfaces increases in the direction from the suction side to the pressure side, so that the sealing surface at the transition from the pressure side to the suction side is narrower in the radial direction than at the transition from the suction side to the pressure side.

[0018] The fluid being pumped is usually oil. The suction side and the pressure side are each defined by an inlet and an outlet of the positive displacement pump, respectively.

[0019] The cam ring or lift contour ring can in particular be an adjustable cam ring.

[0020] The end plate can be formed or connected to the cover in one piece, either by material bonding, positive locking, and / or frictional locking. The positive displacement pump therefore has at least the end plate or the cover, but can also have both. In addition, the positive displacement pump typically includes the cam ring, the rotor, the drive shaft, the majority of the vanes, and the control plate.

[0021] The rotor typically has an at least approximately cylindrical basic shape with a circumferential surface and two circular or round end faces or flat surfaces or base surfaces.

[0022] The axial direction points in the direction of the rotation axis of the drive shaft. The rotation axis lies at the center of the drive shaft.

[0023] The radial direction is defined in particular by the radius of the circular end faces of the rotor.

[0024] It should be noted that at the respective "contact surface" between one of the rotor's end faces and the control plate, and with the end plate or cover that defines the respective sealing surface, there is a certain amount of play and therefore not necessarily full-surface contact, in order to allow the rotor to rotate. For reasons of sealing, this play or gap is limited to an axial width of a few micrometers, whereby a lubricating film preferably does not tear in the gap.

[0025] The sealing surface can, in particular, have a basic shape that is at least approximately arc-shaped or crescent-shaped or asymmetrically hollow-circular.

[0026] The phrase "the transition from the suction side to the pressure side" should be interpreted in relation to the direction of rotation of the positive displacement pump or the drive shaft. This also applies analogously to the transition from the pressure side to the suction side.

[0027] Preferably, both sealing surfaces, which are defined by the two end faces of the rotor, are designed in accordance with the invention. This allows leakage to be reduced particularly effectively.

[0028] It should be noted that the increase in the sealing distance according to the invention, in the direction from the suction side to the pressure side, naturally also implies a reduction in the sealing distance from the pressure side to the suction side. The sealing distance is measured radially or orthogonally to the axis of rotation. The modification of the sealing surface or sealing distance between the suction and pressure sides, or between the suction and pressure areas, according to the invention advantageously reduces internal leakage. In particular, the invention increases the pressure and temperature range of the fluid or oil over which leakage is reduced compared to the prior art. The invention has proven to be particularly advantageous compared to the prior art at elevated temperatures.

[0029] Furthermore, the modification of the sealing surface or sealing path according to the invention also improves power consumption through reduced leakage. In particular, the volume flow rate and torque are optimized, so that a lower torque or a smaller stroke of the cam ring is now required for the same delivery rate. Similarly, a higher delivery rate can be achieved with the same torque or stroke.

[0030] In a preferred embodiment of the invention, the rear wing channel has an eccentricity relative to the drive shaft, wherein an imaginary center of the rear wing channel is arranged offset to the axis of rotation in the direction of stroke or in the direction of the maximum stroke.

[0031] The stroke direction is, in particular, the direction of the stroke movement of the cam ring. In other words, the eccentricity points in the direction of, or is located on the side of, the cam ring where the maximum stroke of the cam ring occurs, or where, during rotor rotation, the blades can be pushed furthest outwards by the limit or inner contour of the cam ring. The stroke direction can depend, in particular, on the inner contour of the cam ring and the direction of rotation of the drive shaft.

[0032] The eccentrically arranged rear wing contour or rear wing geometry allows the inventive extension of the sealing path or widening of the sealing surface from the suction side to the pressure side or towards the shaft connected to the suction to be achieved advantageously.

[0033] The eccentricity corresponds to the amount by which the sealing area is wider at the widest point of the sealing surface than at the narrowest point of the sealing surface.

[0034] Preferably, the eccentricity is maximized to minimize leakage, while simultaneously ensuring that the pump's functionality is not otherwise impaired, particularly while maintaining the full displacement of the vanes.

[0035] Furthermore, when the rear wing channel is arranged offset in the direction of travel or maximum travel, it is preferably necessary to ensure that a sufficient cross-section is available to expel the fluid or oil volume of the rear wing cavities or the rear wing itself into the rear wing channel or the rear wing groove, so that a connection between the rear wing and the rear wing groove is maintained throughout the entire travel of the cam ring. In the embodiment described above, the width and / or depth or the cross-sectional area of ​​the rear wing channel can be uniform throughout. This can be advantageous for a comparatively simple manufacturing process for the rear wing channel.

[0036] The imaginary center of the hindwing channel can preferably correspond to the center point of the hindwing channel, especially if it is circular or round, or if semicircular or arc-shaped sections of the hindwing channel are arranged on an imaginary circle.

[0037] In an alternative or possibly supplementary embodiment of the invention, the rear wing channel has an inner contour on the side facing the sealing surface with a radius that increases in the direction from the suction side to the pressure side.

[0038] In this configuration, the hindwing channel can have, in particular, an elliptical, ovoid, or parabolic inner contour, whereby the width and thus the cross-section of the hindwing channel can vary around its circumference. An outer contour of the hindwing channel can, in particular, be circular or have a constant radius. This can result in an overall sickle shape.

[0039] The imaginary center of the rear wing channel can coincide with the axis of rotation or the center of the drive shaft.

[0040] It is also possible to combine the eccentric arrangement according to claim 2 and the asymmetrical inner contour of the rear wing channel according to claim 3. In this case, the imaginary center of the rear wing channel is different from the center of the drive shaft and the width of the rear wing channel varies over its circumference.

[0041] Notwithstanding the aforementioned embodiments of the invention, the following further embodiments of the invention are explained in more detail below. The following embodiments can be implemented independently or in combination with at least one of the two embodiments mentioned above.

[0042] Such a design of the sealing section has proven to be particularly suitable, which is narrower at the narrowest point of the sealing surface between 0.1 mm and 10 mm, preferably between 1 mm and 5 mm, further preferably between 1.5 mm and 3 mm, and more preferably between 1.8 mm and 2.3 mm, particularly preferably 2 mm, than at the widest point of the sealing surface.

[0043] For example, if the sealing distance at the narrowest point of the sealing surface, or the shortest sealing distance, is 2 mm to 3.5 mm, preferably 3 mm, then the sealing distance at the widest point of the sealing surface, or the longest sealing distance, is 5 mm. Alternatively or additionally, it can be particularly advantageous if the sealing distance at the narrowest point of the sealing surface is between 20% and 60%, preferably between 30% and 50%, more preferably between 35% and 45%, and particularly preferably 40%, narrower than at the widest point of the sealing surface.

[0044] Such a percentage-based restriction of the shortest sealing distance relative to the longest sealing distance is particularly important when the length of the shortest sealing distance deviates significantly from 3 mm. This can be the case, for example, with comparatively large pumps, where it may be advantageous to scale the absolute difference between the shortest and longest sealing distances accordingly, as previously specified in millimeters.

[0045] The deviations between the shortest and longest sealing distances, expressed in millimeters or percent, have proven particularly suitable for solving the problem of reduced leakage according to the invention while simultaneously maintaining the functionality of the movable vanes in order to avoid or prevent blockage of the pump.

[0046] According to the invention, the narrowest point of the sealing surface is preferably located at the transition from the pressure area to the suction area, and the widest point is preferably located at the transition from the suction area to the pressure area.

[0047] Preferably, the cross-section of the rear wing area is always selected such that the cross-section is sufficient to express the volume or oil volume behind the wing into the rear wing groove in order to avoid inhibiting the delivery rate.

[0048] It can be advantageous if the end plate is designed as a second control plate and / or if the end plate is part of the cover. In particular, the end plate can have control elements analogous to the first-mentioned control plate.

[0049] It can be advantageous if the hindwing channel is divided into a first semi-circular partial hindwing channel, which is located on the suction side, and into a second semi-circular partial hindwing channel, which is located on the pressure side.

[0050] The hindwing channel can consist of several sections, the sections preferably being semicircular or arc-shaped and arranged on an imaginary circle.

[0051] Furthermore, it has proven particularly suitable if the opposing partial rear wing channels on the suction side and the pressure side are connected to each other by intermediate throttles. The oil can flow out in a controlled manner through the throttles between the first and second partial rear wing channels, thus building up additional pressure in the partial rear wing channels. With such hydraulic assistance, the wings are advantageously guided radially outwards towards the camber ring.

[0052] In particular, the throttle points may be located in the control plate and / or in the front plate or the cover.

[0053] The positive displacement pump can be designed as a single-stroke and / or adjustable positive displacement pump. The positive displacement pump can also be designed as a double-stroke positive displacement pump.

[0054] Variable displacement pumps feature, in particular, an adjustable cam ring for an adjustable stroke. The adjustability of the cam ring allows the volume change of the pumping chambers or working spaces defined by the rotor, the vanes, and the inner contour of the cam ring to be adjusted during one revolution of the rotor or drive shaft. This also allows the delivery rate of the positive displacement pump to be adjusted, preferably even during operation.

[0055] Preferably, the delivery rate is adjustable to the instantaneous rotational speed of the rotor or drive shaft, so that a constant supply demand of a consumer can be met accordingly. In other words, the positive displacement pump is preferably adjustable such that it delivers a volume flow rate that is as independent of the rotational speed as possible, or the same quantity of fluid or pumped medium per unit of time, regardless of the rotational speed. Such an adjustable positive displacement pump can be used particularly advantageously as a steering pump for a motor vehicle, where the rotational speed of the rotor is coupled to the rotational speed of the vehicle engine, which can fluctuate considerably.

[0056] The described embodiments and further developments of the invention can be combined with each other as desired.

[0057] The invention also relates to a steering system for a motor vehicle with at least one consumer and a displacement pump according to the invention for supplying a fluid to the at least one consumer of the steering system.

[0058] The invention further relates to a transmission for a motor vehicle with at least one consumer and a displacement pump according to the invention for conveying a fluid for the at least one consumer of the transmission.

[0059] The displacement pump of the steering system and the transmission according to the invention is each, in particular, a displacement pump with one or more features as described above. The respective advantages result analogously from the advantages already described. The consumer can, in particular, be a power steering system or an active suspension system.

[0060] Features described in connection with one of the objects of the invention, i.e., the displacement pump, the steering system, and / or the transmission, can also be advantageously implemented for the other objects of the invention. Likewise, advantages mentioned in connection with one of the objects of the invention can also be understood to relate to the other objects of the invention.

[0061] It should also be noted that terms such as "comprehensive," "exhibiting," or "with" do not exclude other characteristics or steps. Furthermore, terms such as "a" or "the," which indicate a singular number of steps or characteristics, do not exclude a plurality of characteristics or steps—and vice versa.

[0062] In a purist embodiment of the invention, however, it may also be provided that the features introduced in the invention with the terms "comprising," "comprising," or "with" are exhaustively listed. Accordingly, one or more lists of features within the scope of the invention may be considered complete, for example, for each claim. The invention may, for instance, consist exclusively of the features mentioned in claim 1.

[0063] It should be noted that designations such as "first" or "second" etc. are primarily used for the purpose of distinguishing between the respective device or process features and are not necessarily intended to indicate that features are mutually dependent or related to each other.

[0064] The following are exemplary embodiments of the invention described in principle with reference to the drawing.

[0065] The figures in the drawing each show preferred embodiments in which individual features of the present invention are combined with one another. Features of an embodiment can also be implemented independently of the other features of the same embodiment and can therefore be readily combined by a person skilled in the art to form further meaningful combinations and subcombinations with features of other embodiments.

[0066] In the figures, identical or functionally equivalent elements, parts or components are designated with the same reference numerals, unless otherwise stated.

[0067] The depicted elements of the figures are not necessarily shown to scale with each other.

[0068] Figure 1 shows a basic cross-section of an embodiment of a positive displacement pump according to the invention, looking towards the end plate or the cover;

[0069] Fig. 2 shows a further schematic cross-section of the embodiment of a device according to the invention.

[0070] Positive displacement pump according to Figure 1 with a view towards the control plate; and

[0071] Fig. 3 shows a schematic diagram of the characteristic curves of a positive displacement pump according to the invention in comparison to the prior art.

[0072] The design and operation of a positive displacement pump or a vane pump are generally known, which is why the following discussion focuses primarily on the parts essential to the invention.

[0073] Figures 1 and 2 show views of a positive displacement pump, in particular a vane pump for pumping a fluid for a consumer of a steering system, with a suction side or inlet side and with a pressure side or outlet side. The positive displacement pump has at least one cam ring 2, a rotor 3, a drive shaft 4 with an axis of rotation x, a plurality of vanes 5, a control plate 6a, an end plate 6b and / or a cover 11.

[0074] It may in particular be a single-stroke and / or adjustable positive displacement pump.

[0075] In a fully assembled positive displacement pump, the control plate 6a and the end plate 6b, or the cover 11, enclose the cam ring 2 and the rotor 3 axially, i.e., in the direction of the axis of rotation x of the drive shaft 4. The axis of rotation x is oriented orthogonally to the drawing surface in Figures 1 and 2.

[0076] Figure 1 shows a schematic cross-section of an embodiment of a positive displacement pump according to the invention, looking towards the end plate 6b. The end plate 6b can preferably be designed as a second control plate. Alternatively or additionally, the end plate 6b can also be part of the cover 11 or be integrally formed or connected to the cover 11 by a material bond, a positive fit and / or a force fit.

[0077] The control plate 6a, the front plate 6b and / or the cover 11 contains a rear wing groove or a rear wing channel 9, which interacts with rear wing spaces to press the wings 5 ​​against the cam ring 2.

[0078] The hindwing channel 9 can be subdivided, in particular, into a first semicircular partial hindwing channel 9a, which is arranged on the suction side, and into a second semicircular partial hindwing channel 9b, which is arranged on the pressure side. Preferably, the opposing partial hindwing channels 9a, 9b of the suction side and the pressure side, respectively, are connected to each other by intermediate throttling points 9c. In particular, the cross-section of the hindwing channel 9 is thereby narrowed in the transition regions.

[0079] The blades 5 are slidably arranged in slots that extend across the width of a surface of the rotor 3 and run at least approximately radially, i.e., in the radial direction of the rotor. When the rotor 3 rotates, the blades 5 are guided along the inner contour of the cam ring 2, as can be seen in Figure 1.

[0080] It should be noted that not all elements shown in Figure 1 lie in the same plane. In particular, the blades 5 and the associated components of the rotor 3 with the slots and the blades 5 arranged therein are not in the same plane as, for example, the rear blade channel 9 of the end plate 6b or the cover 11.

[0081] Each sealing surface 10 is defined by the contact surface of one of the end faces of the rotor 3 with the control plate 6a and with the end plate 6b or the cover 11. In total, the illustrated embodiment of the positive displacement pump thus has exactly two sealing surfaces 10 in this case. In the radial direction, the sealing surface 10 extends over a sealing section 10a, in particular between the drive shaft 4 and the rear vane channel 9. A clearance, preferably as small as possible, is provided at the contact surfaces so that the rotor 3 can rotate despite the sealing effect.

[0082] According to the invention, the sealing path 10a of at least one of the sealing surfaces 10 increases in the direction from the suction side to the pressure side, such that the sealing surface 10 at the transition from the pressure side to the suction side is narrower in the radial direction than at the transition from the suction side to the pressure side. This reduces leakage and improves the power consumption of the positive displacement pump.

[0083] In the embodiment of the invention shown in Figure 1, the rear wing channel 9 has an eccentricity 12 relative to the drive shaft 4. An imaginary center of the rear wing channel 9 (intersection of the dotted reference lines) can be arranged offset in the stroke direction or in the direction of the maximum stroke from the axis of rotation x (intersection of the dashed reference lines).

[0084] Alternatively or additionally, the invention can also be designed such that the rear wing channel 9 has an inner contour on the side facing the sealing surface 10 with a radius that increases in the direction from the suction side to the pressure side. However, this is not shown in the drawing.

[0085] For both of the aforementioned embodiments, it is particularly advantageous if the sealing section 10a is narrower at the narrowest point of the sealing surface 10 than at the widest point of the sealing surface 10, by a difference of between 0.1 mm and 10 mm, preferably between 1 mm and 5 mm, more preferably between 1.5 mm and 3 mm, and further preferably between 1.8 mm and 2.3 mm, particularly preferably 2 mm. For example, the shortest sealing section can be 3 mm and the longest sealing section 5 mm. Figure 2 shows a further schematic cross-section of the embodiment of a positive displacement pump according to the invention as shown in Figure 1, with a view towards the control plate 6a.

[0086] The views shown in Figures 1 and 2, looking at the end plate 6b and the control plate 6a respectively, are in particular mirror-image cross-sections through the embodiment of a positive displacement pump according to the invention. This is recognizable, for example, by the laterally reversed eccentricity 12, which is always oriented in the direction of the maximum stroke. In a fully assembled positive displacement pump, the cross-sections shown in Figures 1 and 2 face each other. The respective asymmetrically hollow circular webs on the end plate 6b or the cover 11 and on the control plate 6a, which are arranged radially between the drive shaft 4 and the rear vane channel 9, each form a contact surface with one of the end faces of the rotor 3, which in turn defines the respective sealing surface 10.

[0087] In contrast to Figure 1, Figure 2 does not show the outer ring 1, the cam ring 2, and the rotor 3 with the vanes 5 arranged therein. Instead, the suction nozzles 7 and the pressure nozzles 8 are shown on the suction and pressure sides of the control plate 6a, respectively. The control plate 6a also has optional control notches on the suction nozzles 7 and pressure nozzles 8. Furthermore, Figure 2 shows the oil supply 13, 14 to the rear vane area, which can be provided via grooves or bores.

[0088] The aspects not described in detail with regard to Figure 2 are analogous to Figure 1.

[0089] Figure 3 shows a schematic diagram of the characteristic curves of a positive displacement pump according to the invention in comparison to the prior art. With respect to the left y-axis, exemplary characteristic curves of the torque as a function of the pump speed of a positive displacement pump 15a according to the invention (dash-dotted curve) and of a conventional positive displacement pump 16a (solid curve) are shown. Similarly, with respect to the right y-axis, exemplary characteristic curves of the flow rate of a positive displacement pump 15b according to the invention (dotted curve) and of a conventional positive displacement pump 16b (dashed curve) are shown.

[0090] Figure 3 illustrates in particular the reduction of torque over almost the entire range of the pump speed plotted on the x-axis, comparing the characteristic curve of a positive displacement pump 15a according to the invention with that of a conventional positive displacement pump 16a. The invention thus reduces power consumption and increases efficiency. The improvement over the prior art can be more pronounced the higher the temperature.

[0091] The drawing with Figures 1 to 3 also serves to disclose a steering system according to the invention for a motor vehicle with at least one consumer and a positive displacement pump according to the invention for supplying a fluid to the at least one consumer of the steering system, and to disclose a transmission according to the invention for a motor vehicle with at least one consumer and a positive displacement pump according to the invention for supplying a fluid to the at least one consumer of the transmission. The positive displacement pump of the steering system or of the transmission can be designed, in particular, as explained with reference to Figures 1 to 3.

[0092] Although the present invention has been described above with reference to preferred embodiments, it is not limited to these, but can be modified in a variety of ways. In particular, the positive displacement pump can be changed or modified in many ways without deviating from the core of the invention.

[0093] For example, the eccentric arrangement of the rear wing channel in a preferred embodiment of the invention is particularly suitable for combination with a reduction, in particular a crescent-shaped reduction, of the width and / or depth of the rear wing channel in the direction from the suction side to the pressure side, as described in DE 10 2013 105 436 A1 of the applicant. While the design of the width and / or depth of the rear wing channel in DE 10 2013 105 436 A1 advantageously alters the flow volume in the rear wing channel in terms of optimal rear wing pressure, it also adversely affects the sealing surface with regard to leakage, as can be seen analogously from the preceding description. This side effect can be avoided or compensated for by the inventive design of the rear wing channel arrangement, since the two measures lead to an increase or decrease in the sealing surface area.This leads to a reduction in the sealing surface on opposite sides of the drive shaft. This allows the leakage of a positive displacement pump according to DE 10 2013 105 436 A1 or other positive displacement pumps to be further reduced using the present invention.

[0094] Reference symbol list:

[0095] 1 outer ring

[0096] 2 Curved Ring

[0097] 3 Rotor

[0098] 4 drive shaft

[0099] 5 wings

[0100] 6a Control board

[0101] 6b Front plate or second control plate

[0102] 7 Sucking kidney

[0103] 8 Pressure kidney

[0104] 9 Hindwing canal

[0105] 9a First partial rear wing channel (suction side)

[0106] 9b Second partial rear wing channel (pressure side)

[0107] 9c Throttle points

[0108] 10 sealing surface

[0109] 10a Sealing section

[0110] 11 lids

[0111] 12 Eccentricity

[0112] 13 Oil supply (rear wing)

[0113] 14 Oil supply (rear wing)

[0114] 15a Torque of a positive displacement pump according to the invention

[0115] 15b Delivery rate of a positive displacement pump according to the invention

[0116] 16a Torque of a conventional positive displacement pump

[0117] 16b Flow rate of a conventional positive displacement pump x axis of rotation

Claims

Claims:

1. Positive displacement pump, in particular vane pump for pumping a fluid for a consumer of a steering system, with a suction side and a pressure side, comprising at least a cam ring (2), a rotor (3), a drive shaft (4) with an axis of rotation (x), a plurality of vanes (5), a control plate (6a), an end plate (6b) and / or a cover (11), wherein a cylindrical surface of the rotor (3) has slots extending over the width of the cylindrical surface, extending at least approximately radially, in which the vanes (5) are slidably arranged, wherein the vanes (5) are guided along the inner contour of the cam ring (2) when the rotor (3) rotates, wherein the control plate (6a), the end plate (6b) and / or the cover (11) contain a rear vane channel (9) which interacts with rear vane spaces for pressing the vanes (5) against the cam ring (2), wherein the control plate (6a) and the end plate (6b) respectivelyThe cover (11) encloses the cam ring (2) and the rotor (3) in the axial direction, wherein a sealing surface (10) is defined by the contact surface of one of the end faces of the rotor (3) with the control plate (6a) and with the end plate (6b) or the cover (11), and wherein the sealing surface (10) extends radially over a sealing section (10a), in particular between the drive shaft (4) and the rear wing channel (9), characterized in that the sealing section (10a) of at least one of the sealing surfaces (10) increases in the direction from the suction side to the pressure side, such that the sealing surface (10) is narrower in the radial direction at the transition from the pressure side to the suction side than at the transition from the suction side to the pressure side.

2. Positive displacement pump according to claim 1, characterized in that the rear wing channel (9) has an eccentricity (12) relative to the drive shaft (4), wherein an imaginary center of the rear wing channel (9) is arranged offset in the stroke direction to the axis of rotation (x).

3. Positive displacement pump according to claim 1 or 2, characterized in that the rear vane channel (9) has an inner contour on the side facing the sealing surface (10) with a radius that increases in the direction from the suction side to the pressure side.

4. Positive displacement pump according to one of claims 1 to 3, characterized in that the sealing section (10a) is narrower at the narrowest point of the sealing surface (10) between 0.1 mm and 10 mm, preferably between 1 mm and 5 mm, more preferably between 1.5 mm and 3 mm, further preferably between 1.8 mm and 2.3 mm, particularly preferably 2 mm, than at the widest point of the sealing surface (10).

5. Positive displacement pump according to one of claims 1 to 4, characterized in that the end plate (6b) is designed as a second control plate and / or the end plate (6b) is part of the cover (11).

6. Positive displacement pump according to one of claims 1 to 5, characterized in that the rear vane channel (9) is divided into a first semi-circular partial rear vane channel (9a) which is arranged on the suction side and into a second semi-circular partial rear vane channel (9b) which is arranged on the pressure side.

7. Positive displacement pump according to claim 6, characterized in that the opposing partial rear vane channels (9a, 9b) of the suction side and the pressure side are connected to each other by intermediate throttling points (9c).

8. Positive displacement pump according to one of claims 1 to 7, characterized in that the positive displacement pump is designed as a single-stroke and / or adjustable positive displacement pump.

9. Steering system for a motor vehicle with at least one consumer and a displacement pump according to one of claims 1 to 8 for supplying a fluid to the at least one consumer of the steering system.

10. Transmission for a motor vehicle with at least one consumer and a displacement pump according to one of claims 1 to 8 for conveying a fluid for the at least one consumer of the transmission.

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