Gearing for a gerotor pump and method for its geometric determination

Abstract

Gearing for a gerotor pump, which has a plurality of external teeth (10) on an inner gerotor element (1) and a plurality of internal teeth (20) on an outer gerotor element (2) that is one greater, wherein a center point (M1) of the inner gerotor element (1) is offset by an eccentricity (e) from a center point (M2) of the outer gerotor element (2), whereby a meshing engagement is formed between the external teeth (10) and the internal teeth (20); characterized in that a contour of the external teeth (10) on the gerotor inner element (1) is defined from a tooth tip (11) continuously over tooth flanks (13) up to a transition radius (14) to a tooth gap or a tooth root (12) essentially by a curve of a single ellipse; wherein the main axis of the ellipse is aligned radially to the gerotor inner element (1), and the center of the ellipse has a radius (R min) on the gerotor inner element (1), which corresponds to the maximum engagement depth of the gerotor outer element (2) between the outer teeth (10) at the meshing engagement.

Description

[0001] The invention relates to a gearing for a low-wear and volumetrically efficient gerotor pump and to a method that enables geometric determination for the development of such gearings.

[0002] Various tooth geometries for gerotor rotor elements have already been developed for use in pumps. Gerotor pumps belong to a type of rotating positive displacement pumps that are preferably used for pumping viscous media such as oils and generate less pulsation with respect to the outlet pressure compared to oscillating positive displacement pumps.

[0003] A gerotor pump known from the prior art is disclosed in US Pat. No. 8,876,504 B2. It comprises a plurality of external teeth on an inner gerotor element and a plurality of internal teeth on an outer gerotor element that are one times larger. A center point of the inner gerotor element is offset by an eccentricity from a center point of the outer gerotor element, thereby forming a meshing engagement between the external teeth and the internal teeth.

[0004] For example, a technical article entitled "The Latest Trends in Oil Pump Rotors for Automobiles" in the magazine SEI Technical Review, number 82, April 2016, pages 59 to 65, explains the technical background and development of tooth geometries for gerotor-type oil pumps known as Parachoid, Megafloid, Geocloid, and Parachoid EX, manufactured by Sumitomo Electric Sintered Alloy, Ltd. In such gerotors, trochoid teeth are traditionally constructed using geometric tools such as epicycles and orst curves. Similar to a spirograph, tooth-forming cycloids are described as the rolling curves of a fixed point on the circumference of a rolling circle, which rolls on a guide curve related to a radius of the toothed rotor.

[0005] The published patent application DE 1002 08 408 A1, however, proposes deviating from the conventional design by using cycloid curves. To reduce noise, a gear toothing for gerotor pumps is described whose tooth tips and roots are formed by second-order or higher-order curves, wherein the curves point tangentially to one another at their ends and at least the curves forming the tooth tips or the curve forming the tooth roots are not cycloids. Furthermore, the curves forming the tooth tips should preferably directly adjoin the curves forming the tooth roots, or less preferably, they can be connected by straight lines. The second-order curves comprise, for example, a conic section. Representations for implementing the tooth geometry include tooth tips and roots formed by a circular arc or an elliptical arc.

[0006] Furthermore, European patent application EP 2 669 521 A1 discloses a rotor for an oil pump to reduce noise. The teeth of the rotor each consist of a plurality of ellipses or circles, with one tooth half in the drive direction and one tooth half opposite the drive direction being designed with different ellipses or circles. The latter tooth half is intended to be slightly wider in the circumferential direction of the rotor.

[0007] The ellipses disclosed in DE 1002 08 408 A1 and in EP 2 669 521 A1 for forming a tooth tip are arranged with their center on a pitch circle of the corresponding rotor and are aligned radially to the rotor with respect to the minor axis, ie the smaller ellipse dimension orthogonal to the major axis of the larger ellipse dimension.

[0008] Continuous efforts are being made to increase the wear resistance of the gerotor elements and reduce noise during the gerotor's movement. Thus, there is still room for improvement with regard to the aforementioned tooth geometries.

[0009] Furthermore, pumps designed for mobile applications are also subject to the aim of increasing power density, i.e. in particular an increase in volumetric flow rate or a reduction in the size or weight of the pump in relation to each other.

[0010] Accordingly, one object of the invention is to provide a tooth geometry for a gerotor pump with an optimized frictional contact between the outer teeth and the inner teeth.

[0011] A further object of the invention is to provide a tooth geometry for a gerotor pump which enables an increase in the effective working volume of the displacement processes between the outer teeth and the inner teeth in relation to a diameter of the gerotor.

[0012] The objects are achieved by a gearing for a gerotor pump having the features of claim 1 and by a method for geometrically determining a gearing for a gerotor pump having the steps of claim 13.

[0013] The gearing for a gerotor pump is characterized in particular by the fact that a contour of the external teeth on the gerotor inner element is defined from a tooth tip continuously over tooth flanks to a transition radius to a tooth gap or a tooth root essentially by a curve of a single ellipse; wherein the main axis of the ellipse is aligned radially to the gerotor inner element, and the center of the ellipse defines a radius on the gerotor inner element which corresponds to the maximum engagement depth of the gerotor outer element between the external teeth at the meshing engagement.

[0014] The corresponding method for the geometric determination of a gearing for a gerotor pump is characterized in particular by the following steps for determining the contour of the external teeth of the gerotor inner element: defining a single ellipse whose main axis is aligned radially to the gerotor inner element, as well as a regularly distributed radial arrangement of such ellipses corresponding to a selected plurality of external teeth; defining contour sections of the external teeth along a curve of the ellipses; defining contour sections between the external teeth along a radius determined by a center point of the ellipses; and defining transition radii which connect the contour sections of the external teeth with the contour sections between the external teeth.

[0015] For the purposes of this disclosure, the terms used have the following definitions.

[0016] The major axis of an ellipse is the longest dimension between two vertices of the ellipse curve. The minor axis of an ellipse is orthogonal to the major axis and is the shorter dimension between two vertices of the ellipse curve.

[0017] The tooth tip refers to a contour section of the toothing on either side of a center point or apex of the outermost radial extent of the tooth. The tooth flank refers to a contour section of the toothing that leads to the tooth tip in the area of ​​the radial extent of the tooth. The tooth root refers to a contour section of the toothing on either side of a center point between two teeth. A tooth gap refers to a contour section of the toothing between two teeth. A transition radius refers to a contour section of the toothing that creates a continuous curvature between two differently aligned ends of the curves of adjacent contour sections.

[0018] A tip circle refers to a circular path along the tooth tips of an external gear and a circular path along the tooth gaps of an internal gear, which create an outermost engagement depth of the gear that extends beyond the pitch circles or pitch circles. A root circle refers to a circular path along the tooth roots of an external gear and a circular path along the tooth tips of an internal gear. A radius R used in this disclosure min Minimum radius refers to the radial dimension to which a tooth root or tooth gap must be recessed to ensure full meshing of a tooth of the other gearing. Eccentricity refers to the dimension between the centers of the rotational axes of the two gerotor elements.

[0019] The condition that a contour is "essentially" defined by a curve includes all contours that exhibit no significant deviation from the given curve. The essentiality of the condition also includes contours that exhibit deviations of a few hundredths of the degree of eccentricity from the given curve.

[0020] In its most general form, the invention provides, for the first time, a purely elliptical external tooth geometry whose radial elliptical extension is greater than an orthogonal elliptical extension in the circumferential direction of the gerotor inner element. The specification of a maximum mesh depth of the gerotor outer element, i.e., a radial dimension between the center of the gerotor inner element and the tip circle of the gerotor outer element during meshing, simultaneously stipulates that the radial extension of the external teeth is also greater than their width. This results in a slimmer and more pointed tooth contour, which has a smaller width in the circumferential direction of the rotor, steeper tooth flanks, and a greater curvature at the apex of the tooth tip.

[0021] The gerotor gearing according to the invention provides several advantages.

[0022] Compared to the previously known gerotor gearings, the gerotor gearing according to the invention comes closer to the goal of a geometric optimization that the contact between the gerotor inner element and the gerotor outer element is limited to the smallest possible rotation angle ranges around the bottom dead center and top dead center of the eccentric stroke.

[0023] The gerotor toothing according to the invention has almost exclusively purely functional contacts between the gerotor inner element and the gerotor outer element. These contacts relate to the drive torque transmission at bottom dead center and serve to seal a delivery cell against leakage flows between the suction and pressure sides of the pump chamber at top dead center, while the largest possible areas between the dead centers are contact-free. More precisely, during the transmission of the drive torque at bottom dead center, partial forces are generated on opposing supporting tooth contacts in the area of ​​top dead center, which better seal a delivery cell as it passes through top dead center.

[0024] The described ideal contact profile cannot yet be achieved by a conventional geometric development methodology, or at least cannot be influenced as specifically as with the method according to the invention for the geometric determination of the gerotor toothing.

[0025] The local contact limitation and the slender elliptical geometry of the outer teeth result in geometrically more favorable options for drive torque transmission. The elliptical tooth flanks provide very flat contact angles between the outer and inner teeth, significantly reducing Hertzian pressure and the resulting frictional torque on the tooth flanks. There is a minimal change in the contact angle between the contacting tooth flanks, reducing frictional contact to a functionally necessary minimum.

[0026] The gerotor toothing according to the invention enables positive hydrodynamic effects to be achieved across almost the entire contact angle range at bottom dead center. More precisely, the very flat contact angles result in quasi-stationary hydrostatic pressure effects, which hydraulically separate the two contact surfaces. Thus, pronounced mixed friction at a linear contact area, as occurs at contact angles of known tooth geometries, can be prevented or at least effectively minimized.

[0027] The slim elliptical geometry of the outer teeth also allows for an increase in the eccentricity between the gerotor inner element and the gerotor outer element, thereby increasing the stroke of the displacement processes and thus the effective working volume between the outer teeth and the inner teeth or the delivery volume per revolution of the gerotor in relation to its diameter.

[0028] Advantageous further developments and specifications of dimensional relationships of the gerotor gearing are the subject of the dependent claims.

[0029] According to one aspect of the invention, the radial extension of the elliptical contour of the external teeth can be a dimension in the range of a factor of 1.0 to 2.0 multiplied by the degree of eccentricity. This value range of a dimensional ratio ensures an elongated elliptical contour section in the area of ​​the tooth flanks up to the beginning of a transition radius, within which a high degree of eccentricity is possible and an optimization of the aforementioned advantages is achieved.

[0030] According to one aspect of the invention, a dimension of the major axis of the ellipse can be a factor of 4 multiplied by the eccentricity. This dimension ensures a long radial extension of the tooth, maintaining a high eccentricity and optimizing the aforementioned advantages. This dimension ratio expresses the fact that the radial dimension of the outer tooth, from the tooth tip to the geometrically defined radius at the maximum engagement depth of the gerotor outer element, is twice the eccentricity.

[0031] According to one aspect of the invention, the minor axis of the ellipse, which is orthogonal to the major axis, can have a dimension of a factor in the range of 0.5 to 2.5, preferably in the range of 1.0 to 2.0, multiplied by the degree of eccentricity. This value range of a dimensional ratio ensures a width of the external tooth within which an optimization of the aforementioned advantages is achieved. By selecting the width of the external tooth based on the minor axis of the ellipse, the overlap of the contact of a tooth pair in the region of the top dead center can be specifically influenced.

[0032] According to one aspect of the invention, a contour of the gerotor inner element between two outer teeth can be concave. By providing an additional, slightly concave recess in the contour of the tooth gap to the radius of maximum engagement of the gerotor outer element in the area of ​​the tooth root, the internal hydraulic work of the displacement processes is reduced, since a larger flow cross-section remains between the gerotor inner element and the gerotor outer element to connect tooth pairs before bottom dead center, allowing the displaced fluid to escape. Furthermore, an enlarged flow cross-section in the tooth gap of the gerotor inner element also serves to prevent compression effects when the teeth mesh at bottom dead center. At the same time, this reduces the pulsation of the output pressure typical of positive displacement pumps, which is directly related to such compression effects.

[0033] According to one aspect of the invention, the concave contour at the apex between two external teeth can have a recess depth corresponding to the radius of maximum engagement of the gerotor outer element of the gerotor inner element, which has a radial dimension of a factor (b) in the range of 0.1 to 0.15 multiplied by the eccentricity (e). This value range of a dimensional ratio ensures a root clearance relative to the internal toothing of the gerotor outer element 2 to form a root space in the form of the concave recess of the contour in the region of the tooth root. Within this value range, an optimization of the aforementioned hydraulic advantages is achieved.

[0034] According to one aspect of the invention, a contour of the inner teeth of the gerotor outer element can result from the intersection of a family of envelope curves that is defined along a movement path of the gerotor by the contour of the outer teeth of the gerotor inner element. This ensures a contour of the inner teeth of the gerotor outer element that matches the relative movements occurring within the gerotor.

[0035] According to one aspect of the invention, the gerotor inner element can have at least five external teeth. The number of six internal teeth and five external teeth forms a limit number of teeth with advantageous gerotor proportions, providing efficient conveying capacity relative to its dimensions. Furthermore, with this number, contact between two adjacent tooth tips of the gerotor inner element and the gerotor outer element is already established at all times in the region of the top dead center, reliably ensuring the formation of a closed conveying cell for transferring the conveyed medium from the suction side to the pressure side of the pump chamber, thus protecting against hydraulic short circuits.

[0036] According to one aspect of the invention, the gerotor outer element can be rotatably mounted in the gerotor pump and, via the meshing engagement, can be driven in rotation by a rotary drive movement of the gerotor inner element. This pump design does not require a rotating control plate, so that a static inlet and outlet into the pump chamber can be provided on the housing side as a suction kidney and a pressure kidney, respectively. It is thus suitable as an advantageous basis for a gerotor pump with which the gearing according to the invention can be implemented.

[0037] Due to the explained advantages of a compact design and power density, a gerotor pump with the gearing according to the invention is particularly suitable for mobile applications such as in vehicle construction, in particular when used as an oil pump for a lubricating oil of an internal combustion engine, a gear oil of an automatic transmission or a hydraulic oil for driving auxiliary units or other actuators up to auxiliary devices of commercial vehicles.

[0038] The invention will be described in detail below using an exemplary embodiment with reference to the accompanying drawings, in which: Fig. 1 a gerotor inner element with external teeth of a gearing for gerotor pumps according to an embodiment of the invention, indicating dimensional relationships; Fig. 2 shows a meshing engagement between the gerotor inner element and a gerotor outer element of a gearing for gerotor pumps according to the embodiment of the invention, indicating dimensional relationships; Fig. 3A-3H shows a sequence of a left-turning movement of a gear for gerotor pumps according to the embodiment of the invention;

[0039] The gerotor comprises an inner gerotor element 1 and an outer gerotor element 2. The gerotor is arranged in a pump chamber of a gerotor pump (not shown). The inner gerotor element 1 engages with a square profile of a driven pump shaft 3 and drags the outer gerotor element 2 along via a meshing engagement. The outer gerotor element 2 is rotatable about its outer circumference and is mounted on a slide bearing in a cylindrical peripheral wall of the pump chamber (not shown).

[0040] When the gerotor rotates counterclockwise, external teeth 10 engage and disengage from internal teeth 20 as they pass through a meshing engagement. In a rotational angle section that lies in the direction of rotation before the bottom dead center of the meshing engagement on an axis of the eccentric offset, a pumped medium, in particular oil, is displaced, which is then sucked in in a rotational angle section that lies behind the bottom dead center in the direction of rotation. The expulsion of the displaced oil and the suction take place in a known manner through an outlet and an inlet of the gerotor pump (not shown), which each open into the pump chamber via a kidney-shaped opening in front of and behind the bottom dead center, respectively.

[0041] Fig. 1 shows an embodiment of the gerotor inner element 1 with the outer teeth 10, which have an elliptical contour from the tooth tip 11 up to the tooth flanks 13, which only ends at a transition radius 14 to the number bases 12. An ellipse is drawn on a downward-facing outer tooth 10, the ellipse curve of which defines the contour of the tooth tip 11 and the tooth flanks 13. According to the provided method for the geometric determination of the gerotor toothing, the essential dimensional relationships are specified as a function of an eccentricity e of the gerotor, i.e. a measure of the offset between a center point M1 of the gerotor inner element 1 and a center point M2 of a gerotor outer element 2.

[0042] An ellipse, which serves as an auxiliary curve for the geometric determination of the contour of the external teeth 10, has a major axis that is aligned radially to the center point M1 of the gerotor inner element 1. The length of the major axis is longer than the eccentricity e by a proportionality factor. In the illustrated embodiment, this proportionality factor is preferably set to the value 4, but it can also deviate from this by several decimal places. The minor axis of the ellipse has a length that is longer than the eccentricity e by a proportionality factor a. In the illustrated embodiment, the proportionality factor a is set to the value 1.5, but it can also take on a different value within a range of 0.5 to 2.5, preferably between 1.0 and 2.0.The proportionality factor a, which defines the length of the minor axis of the ellipse as a function of eccentricity, influences the width of the external teeth 10 in the circumferential direction of the gerotor inner element 1.

[0043] The center of the ellipse, where the major axis and the minor axis intersect, defines a radial dimension on the gerotor inner element 1, up to which a tip circle of the internal toothing of the gerotor outer element 2 penetrates maximally between the external teeth 10 when passing through the meshing engagement, and thus gives a minimum radius R min up to which a tooth root or a tooth gap of the external toothing of the gerotor inner element 1 must be at least removed. Since the radius R minby the center of the ellipses, and the proportionality factor of the main axis of the ellipse in the illustrated embodiment is 4, the radial length of an external tooth 10 corresponds to a factor of 2 of the eccentricity, ie the radius of a tip circle of the external toothing is larger than the radius R by a factor of 2 of the eccentricity e min and the radius of a pitch circle or pitch circle of the gerotor is larger than the radius R by the amount of eccentricity e min .

[0044] As can be seen from the Fig. 1 and Fig. 2, each tooth gap between the outer teeth 1 has a slightly concave recess, which adjoins the transition radii 14 to the tooth flanks 13. An apex of the slightly concave recess lies in the circumferential direction of the gerotor inner element 1 in the center of each tooth gap and simultaneously forms the tooth root 12. At the tooth root 12, the contour of the gerotor inner element 1 has a slightly concave recess compared to the radius R min a recess depth whose radial dimension corresponds to a proportionality factor b to the eccentricity e. In the illustrated embodiment, the proportionality factor b is 0.125, but it can also have a different value within a preferred range of 0.10 to 0.15.

[0045] The radial dimension of the recess depth can also be referred to as a root clearance, which indicates the clearance or distance at maximum meshing between the tooth root 12 of the gerotor inner element 1 and the elevation of the tooth gap between the inner teeth 20 of the gerotor outer element 2 at the bottom dead center of meshing. The root clearance influences the size of a root space with the shape of the concave recess and increases the flow diameter for the oil to escape between the outer teeth 10.

[0046] With reference to the Fig. Figures 3A to 3H describe the rolling behavior of a left-rotating gerotor, i.e., a cyclical relative movement between the gerotor inner element 1 and the gerotor outer element 2. The illustrations show, not necessarily in sequence, various functionally explained rotational angular positions of the gerotor. While the gerotor rotates left or counterclockwise, torque is transferred from the gerotor inner element 1 to the gerotor outer element 2, and the conveying medium or oil is displaced from the inner teeth 20 by the outer teeth 10.

[0047] In Fig. 3A, the left outer tooth 10 begins to come into contact with the inner tooth 20 at a very shallow contact angle. In Fig. 3B, the outer tooth 10 slides progressively into the inner tooth 20 at a very shallow contact angle. Due to the shallow contact angle, a low Hertzian stress is created between the tooth flank 13 of the outer tooth 10 and the opposite contour of the inner tooth 20. In Fig. 3C, the right outer tooth 10, which engages the inner tooth 20, performs a displacement work, whereby the oil in the inner tooth 20 is forced out through a curved wedge gap along the left tooth flank 13 of the outer tooth 10 to the top left. Fig. 3D, the right outer tooth 10 is completely retracted into the inner tooth 20, after which a wedge gap is created along the tooth flanks 13 on both sides of the outer tooth 10, on the pressure side and the suction side.

[0048] Due to the eccentricity, a rotary motion component is superimposed on a pivoting movement between the outer tooth 10 and the inner tooth 20 around the bottom dead center of the meshing engagement. The pivoting movement proceeds from the right side into Fig. 3C, via a center position at the bottom dead center in Fig. 3D, to the left side 3E. The wedge gap on the side of the left tooth flank 13 of the right outer tooth 10 continues to decrease while on the left a subsequent outer tooth 10 moves towards contact with an inner tooth 20. In Fig. 3F, the right outer tooth 10 begins to slide out of the inner tooth 20, while the left outer tooth 10, comparable to Fig. 3A, comes into contact with the following inner tooth 20 and begins to slide into it, thus starting a new displacement.

[0049] Fig. 3G shows a rotational angle position in which two adjacent external teeth 10 each transmit a torque to the gerotor outer element 2 through their flank contact with the internal teeth 20. Fig. Figure 3H again shows the very flat contact angles when the outer teeth 10 move into and out of the inner teeth 20, resulting in very low Hertzian pressures in the area of ​​the contact surfaces of the toothing.

[0050] As can be seen from the Fig. As can be seen in Figures 3A to 3H, the contact surfaces that arise along the tooth flanks 13 can be represented by relatively large equivalent radii. These relatively large equivalent radii result in an increase in the surface contact migrating along the tooth contour compared to conventional tooth geometries. Similar to a design requirement for plain bearings, the large equivalent radii and the flat contact angles minimize wear on the friction pair.

[0051] Hydrostatic effects can be assumed at the sliding gap of the surface contact, not least due to the additional displacement flows along the contact surfaces, which ensure a dynamic lubricating film for wetting the tooth contour. Within the framework of the anticipated operating parameters, the hydrostatic effects theoretically prevent direct surface contact on the tooth flanks 13. This theoretical assumption is consistent with experimental practice in that, according to the inventors' test series, no measurable or visible wear occurred on the gerotor toothing according to the invention.

[0052] As an alternative to the illustrated embodiment with the limit number of teeth 5 / 6 in the ratio of external teeth 10 of the gerotor inner element 1 to internal teeth 20 of the gerotor outer element 2, the gerotor can also be designed with a corresponding number of teeth of 6 / 7, 7 / 8 or 8 / 9, whereby the effect of some of the described advantages of the tooth geometry according to the invention is further enhanced. LIST OF REFERENCE SYMBOLS 1 gerotor inner element 2 Gerotor outer element 3 Pump shaft 10 Outer tooth 11 Tooth head 12 tooth base 13 Tooth flank 14 Transition radius 20 inner tooth a Proportionality factor of the ellipse's minor axis b Proportionality factor of a foot game e eccentricity M1 Center of gerotor inner element M2 Center point of gerotor outer element R f Root circle of the gerotor inner element R minRadius of the engagement depth at the meshing engagement

Claims

[1] Gearing for a gerotor pump, which has a plurality of external teeth (10) on a gerotor inner element (1) and a plurality of internal teeth (20) on a gerotor outer element (2) that is one larger, wherein a center point (M1) of the gerotor inner element (1) is offset by an eccentricity (e) from a center point (M2) of the gerotor outer element (2), whereby a meshing engagement is formed between the external teeth (10) and the internal teeth (20); characterized by , that a contour of the external teeth (10) on the gerotor inner element (1) is defined from a tooth tip (11) continuously over tooth flanks (13) up to a transition radius (14) to a tooth gap or a tooth root (12) essentially by a curve of a single ellipse; wherein the main axis of the ellipse is aligned radially to the gerotor inner element (1), and the center of the ellipse has a radius (R min) on the gerotor inner element (1), which corresponds to the maximum engagement depth of the gerotor outer element (2) between the outer teeth (10) at the meshing engagement. [2] Gearing for a gerotor pump according to claim 1, wherein a radial extent of the elliptical contour of the external teeth (10) is a dimension in the range of a factor of 1.0 to 2.0 multiplied by the measure of the eccentricity (e). [3] Gearing for a gerotor pump according to claim 1 or 2, wherein a dimension of the major axis of the ellipse is a factor of 4 multiplied by the measure of the eccentricity (e). [4] Gearing for a gerotor pump according to one of claims 1 to 3, wherein the minor axis of the ellipse orthogonal to the major axis has a dimension of a factor (a) in the range of 0.5 to 2.5, preferably in the range of 1.0 to 2.0, multiplied by the measure of the eccentricity (e). [5] Gearing for a gerotor pump according to one of claims 1 to 4, wherein a contour of the gerotor inner element (1) between two external teeth (10) is each concave. [6] Gearing for a gerotor pump according to claim 5, wherein the concave contour at the apex between two external teeth (10) has a recess depth to the radius (R min ) of the maximum engagement of the gerotor outer element (2), which has a radial dimension of a factor (b) in the range from 0.1 to 0.15 multiplied by the degree of eccentricity (e). [7] Gearing for a gerotor pump according to one of claims 1 to 6, wherein a contour of the internal teeth (20) of the gerotor outer element (2) results from the intersection of a family of envelope curves which is predetermined along a movement sequence of the gerotor by the contour of the external teeth (10) of the gerotor inner element (1). [8] Gearing for a gerotor pump according to one of claims 1 to 7, wherein the gerotor inner element (1) has a number of at least five external teeth (10). [9] Gearing for a gerotor pump according to one of claims 1 to 8, wherein the gerotor outer element (2) is rotatably mounted in the gerotor pump and is entrained in rotation by a rotary drive movement of the gerotor inner element (1) via the meshing engagement. [10] Use of the gearing according to one of claims 1 to 9 for a gerotor pump for conveying a lubricating oil in an internal combustion engine. [11] Use of the gearing according to one of claims 1 to 10 for a gerotor pump for conveying a transmission oil in a drive train of a vehicle. [12] Use of the gearing according to one of claims 1 to 11 for a gerotor pump for conveying a hydraulic oil in a hydraulic circuit. [13] Method for the geometric determination of a toothing for a gerotor pump, which has a plurality of external teeth (10) on a gerotor inner element (1) and a plurality of internal teeth (20) on a gerotor outer element (2) that is one larger, wherein a center point (M1) of the gerotor inner element (1) is offset by an eccentricity (e) from a center point (M2) of the gerotor outer element (2), whereby a meshing engagement is formed between the external teeth (10) and the internal teeth (20); characterized by a determination of the contour of the outer teeth (10) of the gerotor inner element (1) with the following steps: Defining a single ellipse whose main axis is aligned radially with respect to the gerotor inner element (1), as well as a regularly distributed radial arrangement of such ellipses corresponding to a selected plurality of external teeth (10); Defining contour sections of the external teeth (10) along a curve of the ellipses; Defining contour sections between the external teeth (10) along a radius (R min ), which is determined by a center point of the ellipses; and Defining transition radii (14) which connect the contour sections of the external teeth (10) with the contour sections between the external teeth (10). [14] Method for geometrically determining a gearing for a gerotor pump according to claim 13, further comprising the step: Determination of a radial extension of the elliptical contour of the external teeth depending on the eccentricity (e). [15] Method for geometrically determining a gearing for a gerotor pump according to claim 13 or 14, further comprising the step: Specify a dimension of the major axis of the ellipse as a function of the eccentricity (e). [16] Method for geometrically determining a gearing for a gerotor pump according to one of claims 13 to 15, further comprising the step: Specify a dimension of the orthogonal minor axis of the ellipse as a function of the eccentricity (e). [17] Method for geometrically determining a gearing for a gerotor pump according to one of claims 13 to 16, further comprising the step: Defining concave recesses in the contour sections between the external teeth (10) and specifying a recess depth to the radius (R min ), which is determined by a center of the ellipses, depending on the eccentricity (e). [18] Method for geometrically determining a gearing for a gerotor pump according to one of claims 13 to 17, further comprising the step: Defining a contour of the inner teeth (20) of the gerotor outer element (2) by means of the intersection of a family of envelope curves which is predetermined along a movement sequence of the gerotor by the contour of the outer teeth (10) of the gerotor inner element (1).

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