Electric displacement pump and oil flow circuit in the electric displacement pump

Abstract

The invention relates to an electric displacement pump (1) comprising an electric motor (2), which is in the form of an inrunner or outrunner and which has a stator (3), in particular an overmolded stator, and a permanent magnet rotor (4) which is mounted on a shaft (5), wherein, in a pump head (6), at least two gerotors (7, 8) are arranged on the shaft (5), wherein the shaft (5) is plain-bearing-mounted in a pump housing end shield (14) and a motor end shield (15), and wherein, in the pump head (6), at least two suction ports (9, 10) and at least one pressure port (11) are formed axially at an end face. The invention also relates to an electric displacement pump (1) comprising an electric motor (2), which is in the form of an inrunner or outrunner and which has a stator (3), in particular an overmolded stator, and a permanent magnet rotor (4) which is mounted on a shaft (5), wherein, in a pump head (6), at least two gerotors (7, 8) are arranged on the shaft (5), wherein the shaft (5) is plain-bearing-mounted in a pump housing end shield (14) and a motor end shield (15), and wherein, in the pump head (6), at least two suction ports (9, 10) are formed axially at an end face and at least one pressure port (11) is formed radially. The invention also relates to an oil flow circuit in the electric displacement pump (1).

Description

[0001] Title: Electric positive displacement pump and oil flow circuit in the electric positive displacement pump

[0002] DESCRIPTION

[0003] The invention relates to an electric positive displacement pump according to the preamble of claims 1 and 2 and an oil flow circuit in the electric positive displacement pump according to claims 14 and 15.

[0004] In conventional electric positive displacement pumps, the medium is drawn in through a suction channel inside the motor and conveyed through a pressure channel to an application such as a gearbox or an oil tank. For optimal lubrication and cooling of the positive displacement pump and the connected application, it is necessary that under certain operating conditions an increased flow rate of the medium is required, or that reliable suction from different areas of the pump is ensured, even if no oil is present at a particular point for a certain period. This increased flow rate can only be achieved by using a larger pump or by employing at least two pumps. The disadvantage of this is that more installation space or an additional pump is required to accomplish this task.The object of the invention is to provide an improved electric positive displacement pump that can draw in an increased flow rate of a medium at different positions in the positive displacement pump and can discharge the medium via a common hydraulic connection, even if there is no oil at a position for a certain period of time and only air is drawn in there.

[0005] This problem is solved by the features according to claim 1 or claim 2 as well as the features according to claim 14 or 15.

[0006] The invention is based on the concept of an electric positive displacement pump comprising an electric motor, designed as an internal or external rotor, having a stator (in particular an overmolded one) and a permanent magnet rotor mounted on a shaft, wherein at least two gerotors are arranged on the shaft in a pump head, the shaft being slidably supported in a pump housing end shield and a motor end shield, and wherein at least two suction ports and at least one discharge port are axially formed on the end face of the pump head. The electric positive displacement pump according to the invention can be designed as a gear pump with at least one gerotor, in which the gerotor is formed from two meshing gears.The electric motor used in the positive displacement pump is advantageously designed as a brushless motor and can be easily adapted to a wide range of performance classes by modifying its stator winding, using different magnet qualities in the permanent magnet rotor, or by choosing a design for the permanent magnet rotor as either an IPM (Interior Permanent Magnet) or SPM (Surface Permanent Magnet). The stator is overmolded with a (non-magnetic) plastic material. This overmolding can advantageously also form a sealed motor housing. It is also conceivable to only partially overmold the stator, for example, to minimize the magnetic air gap or to allow for more targeted cooling of the stator.Alternatively, a complete overmolding creates a containment shell that advantageously protects the stator against corrosion from oil or other fluids. Depending on the application, the electric positive displacement pump can be motor-driven with a sensor or sensorless. Advantageously, only one electric motor is required to drive the at least two gerotors and achieve the increased flow rate.

[0007] The invention is based on a further concept of providing an electric positive displacement pump comprising an electric motor, designed as an internal or external rotor, having a stator (in particular an overmolded one) and a permanent magnet rotor mounted on a shaft, wherein at least two gerotors are arranged on the shaft in a pump head, the shaft being slidably supported in a pump housing end shield and a motor end shield, and wherein at least two suction ports are axially arranged at the end face of the pump head and at least one pressure port is radially arranged. The at least one radially arranged pressure port can be produced by simple tooling. No lateral slides are necessary, since the at least one radially arranged pressure port is formed by axially introduced recesses in the pump housing end shield and in the pump head and by their interaction.These can be manufactured using a simple open-close tooling technique, either injection molding or compression molding. The electric positive displacement pump according to the invention can be designed as a gear pump with at least one gerotor, in which the gerotor is formed from two meshing gears. The electric motor used in the positive displacement pump is advantageously designed as a brushless motor and can be very easily adapted to a wide range of performance classes by modifications to its stator winding, different magnet qualities of the permanent magnets used in the permanent magnet rotor, or by the design of the permanent magnet rotor as a so-called IPM (Interior Permanent Magnet) or SPM (Surface Permanent Magnet). The stator is provided with an overmolding made of a (non-magnetic) plastic material. The overmolding can advantageously also form a sealed motor housing.It is conceivable to only partially overmold the stator, for example to minimize the magnetic air gap or to enable more targeted cooling of the stator. Alternatively, a complete overmolding creates a containment shell that effectively protects the stator against corrosion from oil or other fluids.

[0008] Depending on the application, the electric positive displacement pump can be motor-driven with a sensor or sensorless. Advantageously, only one electric motor is required to drive the at least two gerotors in order to achieve the increased flow rate.

[0009] A further advantage of the electric positive displacement pump according to the invention lies in its modular design. Depending on the desired application, the design can be implemented as a single-flow or multi-flow pump, i.e., with one or more gerotors forming so-called pump stages. A multi-flow positive displacement pump is preferred when a higher flow rate is required or when it is necessary to draw in medium from different areas.

[0010] In a single-flow positive displacement pump, a suction port and / or a pressure port can be formed axially at the front of the pump head or radially on the pump.

[0011] In a multi-flow positive displacement pump, at least one suction port and / or at least one pressure port can be formed axially on the end face of the pump head and / or radially on the pump.

[0012] According to one embodiment, the shaft and / or the permanent magnet rotor is axially positioned and / or secured by pressing on at least one gerotor. The permanent magnet rotor is mounted on the shaft by pressing it onto the shaft. However, the permanent magnet rotor can also be attached to the shaft by other methods known to those skilled in the art. The at least two gerotors are pressed onto the shaft or arranged on the shaft by other fastening methods known to those skilled in the art. At least one of the two gerotors is pressed onto the shaft and / or arranged on the shaft by other fastening methods known to those skilled in the art. Pressing on at least one of the gerotors to the shaft axially positions and secures both the shaft and the permanent magnet rotor without requiring an additional component.

[0013] In a further development, at least one gerotor is arranged axially spaced on the shaft in the pump head relative to the second gerotor, which is provided in the pump housing bearing shield. Here, the at least one gerotor is received in a recess in the pump head, and the at least second gerotor is received in a recess in the pump housing bearing shield.

[0014] According to a further embodiment, the at least two gerotors are each formed by an inner rotor and an outer rotor, which are arranged in the pump head and / or the pump housing end shield. These at least two gerotors have the same design and are received in recesses in the pump head or the pump housing end shield, ensuring spacing between them. Depending on the desired application, the inner rotors of the two gerotors can be rotated relative to each other at a specific angle or positioned in the same direction, i.e., tooth-to-tooth, on the shaft. In the case of angular offset, the teeth of the inner rotors are thus arranged offset from each other.

[0015] Advantageously, the at least two gerotors each form a pump stage, with their own suction port and a common pressure port. Each pump stage delivers oil independently. This has the advantage that one pump stage can continue to deliver oil even if air is drawn in by another pump stage(s). The two independently operating pump stages ensure continuous oil delivery without the risk of failure or damage, for example, due to dry running of the positive displacement pump or the application. Furthermore, this pump stage configuration does not result in a pressure boosting stage, but rather an increase in the delivery rate due to the parallel operation of the pump stages.

[0016] According to a further preferred embodiment, a motor bearing shield is arranged between the electric motor and the pump housing end shield. The motor bearing shield separates the motor interior from the pumping chamber and can be made of a thermoset material. The pump housing end shield and / or the motor bearing shield are integrated into the pump head, thus eliminating the need for seals between these components. A further advantage is that the electric motor can be manufactured as a separate motor assembly independent of the pumping unit (pump assembly) and connected using a small number of seals. The pump housing end shield and / or the pump head can be made of a thermoplastic or thermoset material. Depending on the application, the motor bearing shield and / or the pump housing end shield and / or the pump head can also be made of other materials known to those skilled in the art.

[0017] In a further development, the shaft is supplied with lubricating oil via oil channels in the pump housing end shield and / or motor end shield. The bearing points are additionally supplied with oil from at least one pressure kidney or at least one shadow port pressure kidney, thus ensuring sufficient lubrication. The shaft is also axially supported by the pressed-on permanent magnet rotor. As an alternative to lubricating oil, other fluids known to those skilled in the art with lubricating properties can be used, such as ester-containing or (water-)glycol-containing fluids. For optimal lubrication, the oil channels can be arranged directly on the shaft.

[0018] According to a further embodiment, the shaft has a drive contour on which at least one gerotor is positively engaged. Here, the second gerotor, i.e., the second pump stage, is positively engaged on the drive contour on the shaft and is driven by the drive contour. The axially determined bearing of the shaft can be achieved by the at least one force-fit (pressed-on) gerotor. Alternatively, several spaced-apart gerotors can be arranged or attached to the drive contour. The drive contour has a 2-flat or 4-flat spline, a splined connection, or a similar design.

[0019] In this design, at least one suction port in the pump head is operatively connected to a first channel in the pump housing end shield and the motor end shield. Oil is drawn into the motor chamber through this first channel and flows around or through the permanent magnet rotor. The oil in the motor chamber also serves to dissipate heat from the stator winding and electronics. The first channel can, for example, serve as a direct fluid connection from the pump head to the motor chamber, or it can be connected to a corresponding opening in the motor end shield or the electric motor housing. Alternatively, the first channel itself can run through an opening in the electric motor housing or along and / or through the stator, allowing oil or fluid to flow directly into the motor chamber. The overmolded or encapsulated stator allows oil to flow through the motor chamber without damaging the stator components or other motor parts.The overmolded stator, for example, offers the advantage of a sealed motor housing to protect the motor components. The permanent magnet rotor features protruding permanent magnets that act like blade blades, ensuring fluid flow and turbulence. This creates a defined turbulence and circulation effect similar to a paddle pump. This also contributes to improved heat dissipation from the stator winding and electronics. It is also possible to have the permanent magnets protrude on both sides or to have them flush with the rotor lamination stack.

[0020] In a further development, at least one suction port in the pump head is operatively connected to at least one suction nozzle and at least one pressure nozzle in at least one gerotor, and / or at least one shadow port suction nozzle is formed on at least one gerotor. The oil is drawn into at least one gerotor and conveyed through at least one pressure nozzle into the engine compartment or to at least one common pressure outlet.

[0021] At least one shadow port suction nozzle can be fitted to at least one gerotor. This at least one shadow port suction nozzle is not strictly necessary for the oil flow circuit, as the oil flow circuit functions correctly even without it. However, the use of at least one shadow port suction nozzle also helps to balance the forces acting on the at least one gerotor.

[0022] According to a further embodiment, at least a second channel is formed in the engine bearing shield and / or pump housing bearing shield and is operatively connected to at least one suction nozzle. The oil is conveyed through the second channel from the engine interior, via at least one gerotor, to the at least one pressure outlet.

[0023] Furthermore, at least one axially arranged pressure port on the end face of the pump head, or at least one radially arranged pressure port in the motor bearing shield and / or in the pump housing bearing shield and / or in the pump head, is formed by a third channel and is operatively connected to at least one suction port and at least one pressure port in at least two gerotors, and / or at least one shadow port pressure port is formed on at least one gerotor. The at least two gerotors advantageously direct the oil into at least one common pressure outlet.

[0024] At least one shadow port pressure kidney can be configured on at least one gerotor. The presence of at least one shadow port pressure kidney is not strictly necessary for the oil flow circuit, as the oil flow circuit functions correctly even without it. However, the use of at least one shadow port pressure kidney can also help to balance the forces acting on the gerotor.

[0025] Furthermore, the invention is based on the idea of ​​specifying an oil flow circuit in the electric positive displacement pump, wherein oil

[0026] - is drawn in through at least one first axially arranged suction port and / or a second axially arranged suction port in the pump head;

[0027] - is conveyed through the pump housing bearing shield and the motor bearing shield into a motor interior of the electric motor, thereby flowing around and / or through the permanent magnet rotor; - is drawn into at least one gerotor through a second channel in the motor bearing shield and / or pump housing bearing shield and

[0028] - through the at least one axially arranged pressure port through the third channel, which is in operative connection with at least one pressure kidney, in the common pressure outlet from the positive displacement pump.

[0029] The first and / or second suction port can also be radially mounted on the positive displacement pump.

[0030] The permanent magnet rotor can be designed with protruding permanent magnets on its rotor assembly. These protruding permanent magnets further promote turbulence and forced fluid flow, which in turn aids heat dissipation from the stator winding and electronics via the oil inside the motor.

[0031] Furthermore, the invention is based on the idea of ​​specifying an oil flow circuit in the electric positive displacement pump, wherein oil

[0032] - is drawn in through at least one first axially arranged suction port and / or a second axially arranged suction port in the pump head;

[0033] - is conveyed through the pump housing bearing shield and the motor bearing shield into a motor interior of the electric motor, thereby flowing around and / or through the permanent magnet rotor;

[0034] - is drawn in through a second channel in the motor bearing shield and / or pump housing bearing shield to at least one gerotor and

[0035] - through the at least one radially arranged pressure port through the third channel, which is in operative connection with at least one pressure kidney, in the common pressure outlet from the positive displacement pump.

[0036] The first and / or second suction port can also be radially mounted on the positive displacement pump.

[0037] Alternatively, in a single-flow positive displacement pump, the oil is drawn in through a suction port located axially at the end face of the pump head or radially on the pump, conveyed through the pump housing end shield and the motor end shield into a motor interior of the electric motor and flows around and / or through the permanent magnet rotor; drawn in through a second channel in the motor end shield and / or pump housing end shield to a gerotor and conveyed out of the positive displacement pump through the third channel, which is in operative connection with at least one pressure kidney, via a pressure port located axially at the end face or radially on the pump.

[0038] It would also be conceivable to reverse the direction of rotation of the motor compared to the previously described embodiments, that is, to operate it in counter-rotation. In this configuration, the at least one pressure channel and the at least two suction channels exchange their functions, so that the oil or fluid can, for example, be drawn in through one port and discharged through two ports.

[0039] Reference symbol list

[0040] 1. Positive displacement pump

[0041] 2. Electric motor

[0042] 3. Stator

[0043] 4. Permanent magnet rotor

[0044] 5th wave

[0045] 6. Pump head

[0046] 7. First gerotor

[0047] 8. Second gerotor

[0048] 9. First suction connection

[0049] 10. Second suction port

[0050] 11. Pressure connection

[0051] 12. Inner rotor

[0052] 13. Outer rotor

[0053] 14. Pump housing bearing shield

[0054] 15. Engine mount plate

[0055] 16. Oil channels

[0056] 17. Driver contour

[0057] 18. Engine compartment

[0058] 19. First pump stage

[0059] 20. Second pump stage

[0060] A first channel

[0061] B second channel

[0062] Channel C third channel

[0063] D Pressure kidney

[0064] E Sucking Kidney

[0065] F Shadow-Port pressure kidney

[0066] G Shadow-Port Suction Kidney The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings. These show:

[0067] Fig. 1 shows a sectional view of the electric positive displacement pump according to the invention in a preferred embodiment;

[0068] Fig. 2 shows a sectional view of the positive displacement pump according to Fig. 1 with the oil flow circuit according to the invention;

[0069] Fig. 3 shows a sectional view of another electric positive displacement pump according to the invention, based on a further preferred embodiment and

[0070] Fig. 4 shows a sectional view of the positive displacement pump according to Fig. 3 with the oil flow circuit according to the invention.

[0071] Fig. 1 shows a sectional view of the electric positive displacement pump according to the invention.

[0072] (I) comprising an electric motor (2) designed as an internal or external rotor, having a stator (3), in particular overmolded, and a permanent magnet rotor (4) mounted on a shaft (5), wherein at least two gerotors (7, 8) are arranged on the shaft (5) in a pump head (6), and wherein at least two suction ports (9, 10) and at least one pressure port (11) are axially formed on the end face of the pump head (6). At least one gerotor (7) is arranged axially spaced on the shaft (5) in the pump head (6) relative to the second gerotor (8), which is preferably provided in the pump housing bearing shield (14). The at least two gerotors (7, 8) are each formed by an inner rotor (12) and an outer rotor (13) which are arranged in a pump housing bearing shield (14) and each form a pump stage (19, 20) which has its own suction port (9, 10) and a common pressure port.

[0073] (II) terminate. A motor bearing shield (15) is arranged between the electric motor (2) and the pump housing bearing shield (14). The shaft (5) is supported by plain bearings in the pump housing bearing shield (14) and the motor bearing shield (15) and is supplied with lubricating oil via oil channels (16) in the pump housing bearing shield (14) and / or motor bearing shield (15). The bearing points are additionally supplied with oil from at least one pressure kidney (D) or from at least one shadow port pressure kidney (see Fig. 2) and are thus adequately lubricated. In addition, the shaft (5) has a drive contour (17) on which at least one gerotor (7) is arranged.

[0074] Fig. 2 shows a sectional view of the positive displacement pump according to Fig. 1 with the oil flow circuit according to the invention. At least one suction port (9) in the pump head (6) is operatively connected to a first channel (A) in the pump housing end shield (14) and in the motor end shield (15), and at least one suction port (10) in the pump head (6) is operatively connected to at least one suction port (E) and at least one pressure port (D) in at least one gerotor (7, 8). At least one second channel (B) is formed in the motor end shield (15) and / or pump housing end shield (14) and is operatively connected to at least one suction port (E). Alternatively, at least one shadow port suction port (G) can be formed on at least one gerotor (7, 8).The at least one shadow-port suction kidney (G) is not strictly necessary for the oil flow circuit, as the oil flow circuit functions correctly even without the formation of at least one shadow-port suction kidney (G) on the at least one gerotor (7, 8). The use of at least one shadow-port suction kidney (G) additionally compensates for the forces acting on the at least one gerotor (7, 8). At least one axially arranged end-face pressure port (11) in the pump head (6) or at least one radially arranged pressure port (11) in the motor bearing shield (15) and / or in the pump housing bearing shield (14) and / or in the pump head (6) is formed by a third channel (C) and is operatively connected to at least one pressure kidney (D) in at least two gerotors (7, 8). Alternatively, at least one shadow-port pressure kidney (F) can be formed on at least one gerotor (7, 8).The at least one shadow-port pressure kidney (F) is not strictly necessary for the oil flow circuit, as the oil flow circuit functions correctly even without at least one shadow-port pressure kidney (F) on at least one gerotor (7, 8). The use of at least one shadow-port pressure kidney (F) additionally compensates for the forces acting on the at least one gerotor (7, 8).In the oil flow circuit, oil is drawn in through at least one first axially arranged suction port (9) and a second axially arranged suction port (10) in the pump head (6), conveyed through the pump housing bearing shield (14) and the motor bearing shield (15) into a motor interior (18) of the electric motor (2) through the channel (A) and flows around and / or through the permanent magnet rotor (4), is drawn in through a second channel (B) in the motor bearing shield (15) and / or pump housing bearing shield (14) to at least one gerotor and conveyed through the at least one axially arranged pressure port (11) through the third channel (C), which is in operative connection with at least one pressure kidney (D), into the common pressure outlet of the positive displacement pump (1).

[0075] Fig. 3 shows a sectional view of another electric positive displacement pump (1) according to the invention, comprising an electric motor (2) designed as an internal or external rotor, having a stator (3), in particular an overmolded stator, and a permanent magnet rotor (4) mounted on a shaft (5), wherein at least two gerotors (7, 8) are arranged on the shaft (5) in a pump head (6), and wherein at least two suction ports (9, 10) are axially arranged at the end face of the pump head (6), and at least one discharge port (11) is radially arranged. At least one gerotor (7) is arranged axially spaced on the shaft (5) in the pump head (6) relative to the second gerotor (8), which is preferably provided in the pump housing bearing shield (14).The at least two gerotors (7, 8) are each formed by an inner rotor (12) and an outer rotor (13) arranged in a pump housing end shield (14) and each form a pump stage (19, 20) with its own suction port (9, 10) and a common pressure port (11). A motor end shield (15) is arranged between the electric motor (2) and the pump housing end shield (14). The shaft (5) is supported by plain bearings in the pump housing end shield (14) and the motor end shield (15) and is supplied with lubricating oil through oil channels (16) (see Fig. 1 or 2) in the pump housing end shield (14) and / or motor end shield (15). The bearing points are additionally supplied with oil from at least one pressure kidney (D) or from at least one shadow port pressure kidney (see Fig. 4) and are thus adequately lubricated. In addition, the shaft (5) has a drive contour (17) on which at least one gerotor (7) is arranged.

[0076] Fig. 4 shows a sectional view of the positive displacement pump according to Fig. 3 with the oil flow circuit according to the invention. At least one suction port (9) in the pump head (6) is operatively connected to a first channel (A) in the pump housing end shield (14) and in the motor end shield (15), and at least one suction port (10) in the pump head (6) is operatively connected to at least one suction port (E) and at least one pressure port (D) in at least one gerotor (7, 8). At least one second channel (B) is formed in the motor end shield (15) and / or pump housing end shield (14) and is operatively connected to at least one suction port (E). Alternatively, at least one shadow port suction port (G) can be formed on at least one gerotor (7, 8).The at least one shadow-port suction kidney (G) is not strictly necessary for the oil flow circuit, as the oil flow circuit functions correctly even without the formation of at least one shadow-port suction kidney (G) on the at least one gerotor (7, 8). The use of at least one shadow-port suction kidney (G) additionally compensates for the forces acting on the at least one gerotor (7, 8). At least one axially arranged end-face pressure port (11) in the pump head (6) or at least one radially arranged pressure port (11) in the motor bearing shield (15) and / or in the pump housing bearing shield (14) and / or in the pump head (6) is formed by a third channel (C) and is operatively connected to at least one pressure kidney (D) in at least two gerotors (7, 8). Alternatively, at least one shadow-port pressure kidney (F) can be formed on at least one gerotor (7, 8).The at least one shadow-port pressure kidney (F) is not strictly necessary for the oil flow circuit, as the oil flow circuit functions correctly even without at least one shadow-port pressure kidney (F) on at least one gerotor (7, 8). The use of at least one shadow-port pressure kidney (F) additionally compensates for the forces acting on the at least one gerotor (7, 8).In the oil flow circuit, oil is drawn in through at least one first axially arranged suction port (9) and a second axially arranged suction port (10) in the pump head (6), conveyed through the pump housing bearing shield (14) and the motor bearing shield (15) into a motor interior (18) of the electric motor (2) through the channel (A) and flows around and / or through the permanent magnet rotor (4), is drawn in through a second channel (B) in the motor bearing shield (15) and / or pump housing bearing shield (14) to at least one gerotor and conveyed through the at least one axially arranged pressure port (11) through the third channel (C), which is in operative connection with at least one pressure kidney (D), into the common pressure outlet of the positive displacement pump (1).

[0077] Preferably, in the described embodiments, the stator is provided with a complete or partial overmolding made of a (non-magnetic) plastic material. However, it is also conceivable to mount the stator in a housing without overmolding, using a canned housing.

Claims

PATENT CLAIMS 1. Electric positive displacement pump (1) comprising an electric motor (2) designed as an internal or external rotor, having a stator (3), in particular an overmolded one, and a permanent magnet rotor (4) mounted on a shaft (5), wherein at least two gerotors (7, 8) are arranged on the shaft (5) in a pump head (6), wherein the shaft (5) is slidably supported in a pump housing bearing shield (14) and a motor bearing shield (15), and wherein at least two suction ports (9, 10) and at least one pressure port (11) are formed axially on the end face of the pump head (6).

2. Electric positive displacement pump (1) comprising an electric motor (2) designed as an internal or external rotor, having a stator (3), in particular an overmolded one, and a permanent magnet rotor (4) mounted on a shaft (5), wherein at least two gerotors (7, 8) are arranged on the shaft (5) in a pump head (6), wherein the shaft (5) is slidably mounted in a pump housing bearing shield (14) and a motor bearing shield (15), and wherein at least two suction ports (9, 10) are formed axially on the end face and at least one pressure port (11) is formed radially in the pump head (6).

3. Electric positive displacement pump according to claim 1 or 2, wherein the shaft (5) and / or the permanent magnet rotor (4) is axially positioned and / or secured by pressing on at least one gerotor (7, 8).

4. Electric positive displacement pump according to claim 1, 2 or 3, wherein at least one gerotor (7) in the pump head (6) is arranged axially spaced from the second gerotor (8) which is provided in the pump housing bearing shield (14) on the shaft (5).

5. Electric positive displacement pump according to one of the preceding claims, wherein the at least two gerotors (7, 8) are each formed by an inner rotor (12) and an outer rotor (13) which are arranged in the pump head (6) and / or in the pump housing bearing shield (14).

6. Electric positive displacement pump according to one of the preceding claims, wherein the at least two gerotors (7, 8) each form a pump stage (19, 20) which have their own suction port (9, 10) and open into a common pressure port (11).

7. Electric positive displacement pump according to one of the preceding claims, wherein the motor bearing shield (15) is arranged between the electric motor (2) and the pump housing bearing shield (14).

8. Electric positive displacement pump according to one of the preceding claims, wherein the shaft (5) is supplied with lubricating oil through oil channels (16) in the pump housing bearing shield (14) and / or motor bearing shield (15).

9. Electric positive displacement pump according to one of the preceding claims, wherein the shaft (5) has a drive contour (17) on which at least one gerotor (7) is arranged in a form-fitting manner.

10. Electric positive displacement pump according to one of the preceding claims, wherein at least one suction port (9) in the pump head (6) is operatively connected to a first channel (A) in the pump housing bearing shield (14) and in the motor bearing shield (15).

11. Electric positive displacement pump according to one of the preceding claims, wherein at least one suction port (10) in the pump head (6) is operatively connected to at least one suction kidney (E) and at least one pressure kidney (D) in at least one gerotor (7, 8) and / or at least one shadow port suction kidney (G) is formed on at least one gerotor (7, 8).

12. Electric positive displacement pump according to one of the preceding claims, wherein at least a second channel (B) is formed in the motor bearing shield (15) and / or pump housing bearing shield (14) and is in operative communication with at least one suction kidney (E).

13. Electric positive displacement pump according to one of the preceding claims, wherein at least one axially arranged end-face pressure port (11) in the pump head (6) or at least one radially arranged pressure port (11) in the motor bearing shield (15) and / or in the pump housing bearing shield (14) and / or in the pump head (6) is formed by a third channel (C) and is operatively connected to at least one pressure kidney (D) in at least two gerotors (7, 8) and / or at least one shadow port pressure kidney (F) is formed on at least one gerotor (7, 8).

14. Oil flow circuit in the electric positive displacement pump (1) according to claim 1 , wherein oil - is drawn in through at least one first axially arranged suction port (9) and / or a second axially arranged suction port (10) in the pump head (6); - is conveyed through the pump housing bearing shield (14) and the motor bearing shield (15) into a motor interior (18) of the electric motor (2) through the channel (A) and thereby flows around and / or through the permanent magnet rotor (4); is drawn into at least one gerotor through a second channel (B) in the motor bearing shield (15) and / or pump housing bearing shield (14) and - through the at least one axially arranged pressure port (11) through the third channel (C), which is in operative connection with at least one pressure kidney (D), in the common pressure outlet from the positive displacement pump (1).

15. Oil flow circuit in the electric positive displacement pump (1) according to claim 2, wherein oil - is drawn in through at least one first axially arranged suction port (9) and / or a second axially arranged suction port (10) in the pump head (6); - is conveyed through the pump housing bearing shield (14) and the motor bearing shield (15) into a motor interior (18) of the electric motor (2) and thereby flows around and / or through the permanent magnet rotor (4); is drawn through a second channel (B) in the motor bearing shield (15) and / or pump housing bearing shield (14) to at least one gerotor and - through the at least one radially arranged pressure port (11) through the third channel (C), which is in operative connection with at least one pressure kidney (D), in the common pressure outlet from the positive displacement pump (1).

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