Electric fluid pump with improved fluid flow

Abstract

The present invention relates to an electric fluid pump (1), comprising a housing (2) having a suction port (3) and a discharge port (4), an electric motor (5) having a stator (6) and a rotor (7) which is received inside the stator (6) with an annular gap (8) and is rotatable about an axis of rotation (X), a pump unit (17) which is in driving connection with the rotor (7) via a rotor shaft (10) and which has a suction inlet (11) and a discharge outlet (12), a control unit (13), the rotor (7) incorporating an impeller (15) in order to force the fluid flow to circulate at least axially inside the rotor (7), around the rotor (7) in the annular gap (8) and axially between the control unit (13) and the electric motor (5). Figure for abstract: Figure 1

Description

Title of the invention: Electric fluid pump with improved fluid flow

[0001] The present invention relates to electric motor-driven liquid pumps for use in the automotive industry, such as, for example, lubricating oil pumps, cooling oil pumps, auxiliary oil pumps or actuator pumps.

[0002] In general, an electric motor and a control unit generate heat during operation and the performance of the electric motor is inversely proportional to the generated heat. The liquid pump driven by an electric motor also generates heat and the generated heat is detrimental to the performance of the electric motor and the performance of the associated fluid pump. One possibility for cooling the electric motor is the use of the pumping fluid in the electric motor driven liquid pump. Conventional techniques for cooling the electric motor of the electric motor driven liquid pump are suboptimal.

[0003] Therefore, it is necessary to improve the cooling behavior of the electric motor and the pump to achieve higher efficiency and reliability.

[0004] It is therefore an object of the present arrangement to provide an assembly which overcomes the aforementioned and other disadvantages of known arrangements, and to provide improved cooling performance of the electric motor, the control unit and the motor terminals.

[0005] In the present invention, the electric fluid pump, in particular an oil pump for supplying a clutch actuator, a gearbox actuator, a lubrication system and / or a cooling system of a drive train, comprises a housing having at least one suction port and at least one discharge port, an electric motor having a stator and a rotor which is received inside the stator with an annular gap and is rotatable about an axis of rotation, a pump unit which is in driving connection with the rotor via a rotor shaft and which has a suction inlet in fluid communication with the suction port and a discharge outlet in fluid communication with the discharge port, a control unit for driving the electric motor, the rotor incorporates an impeller in order to force the fluid flow to circulate at least axially inside the rotor,around the rotor in the annular gap and axially between the control unit and the electric motor.

[0006] One of the advantages of the present arrangement is to increase the amount of fluid flowing between the electric motor and the control unit, which allows heat transfer by convection or conduction. Axially between the control unit and the electric motor means a region between the control unit and the electric motor where fluid flow is able to circulate in order to cool the control unit.

[0007] In one embodiment, the housing comprises a partition wall which extends substantially transversely to the axis of rotation and is axially between the control unit which is in a dry zone and the electric motor which is in a wet zone in fluid communication with the pump unit.

[0008] Alternatively, the electric motor and the control unit are in fluid communication with the pump unit. In this embodiment, there is no dividing wall or the dividing wall has at least one opening for fluid circulation.

[0009] According to the invention, the rotor comprises a tubular main body and a part receiving the rotor shaft, preferably with complementary shapes.

[0010] According to the invention, the impeller has several blades constituting a mechanical connection between the part receiving the rotor shaft and the tubular main body. The arrangement is used to pump the fluid and force the fluid flow.

[0011] Preferably, the blades have a helical shape or straight bars. These shapes allow better pumping to force the flow of fluid.

[0012] Preferably, the rotor shaft receiving portion, the blades and the tubular main body are formed integrally with each other from a plastic material, preferably an injection-molded plastic material. The rotor manufacturing process is easily carried out.

[0013] Preferably, the rotor comprises a stack of rotor laminations which are received on the tubular main body and have a plurality of magnet cavities and a plurality of permanent magnets which are received in the magnet cavities. Preferably, the stack of rotor laminations and the main body are obtained using an overmolding process.

[0014] Preferably, the fluid flow is able to circulate in the magnet cavities. It increases the cooling of the rotor magnets.

[0015] Alternatively, the tubular main body of the rotor is made of plastic material in which magnetic particles are incorporated.

[0016] Preferably, a temperature sensor is attached to the control unit. This feature ensures fluid flow near the temperature sensor if it is in the dry zone or directly over the temperature sensor if it is in contact with the oil. In both cases, the flow improves the accuracy of the temperature sensor.

[0017] Preferably, the stator of the electric motor comprises a plurality of stator metal laminations, which carry stator windings and have radially inner teeth adjoining the annular gap, a free space being present between two adjacent stator windings and allowing fluid communication with the annular gap. The gap between two adjacent teeth helps to cool the stator winding.

[0018] In general, based on the present invention, cooling allows the use of components that are less temperature stable and therefore less expensive.

[0019] The present invention may be better understood with reference to the following description and drawings. The components in the figures are not necessarily to scale, the emphasis being rather on illustrating the principles of the arrangement. In addition, in the figures, like reference numerals designate corresponding parts. In the drawings:

[0020] [Fig.l] illustrates a sectional view of one embodiment of an assembly configured according to the present invention;

[0021] [Fig.2] illustrates a sectional view of the embodiment with a flow direction different from the flow direction as shown in [Fig.l];

[0022] [Fig.3] illustrates a front view of the rotor;

[0023] [Fig.4] illustrates a perspective view of the rotor;

[0024] [Fig.5] illustrates the sectional view of the electric motor showing stator and rotor parts.

[0025] The figures are not necessarily to scale and the size of certain parts may be exaggerated to more clearly illustrate the example shown. In addition, the drawings provide examples and / or examples in accordance with the description; however, the description is not limited to the examples and / or examples provided in the drawings.

[0026] In the following description, reference is made to the accompanying drawings, which are part thereof, and in which there are illustrated specific embodiments in which the invention may be applied. These embodiments are described in sufficient detail to enable a person skilled in the art to practice the invention, and it will be understood that the embodiments may be combined or other embodiments may be used and that structural and logical modifications may be made without departing from the scope of the present invention. The following detailed description should therefore not be construed as limiting and the scope of the present invention is defined by the appended claims and their equivalents.

[0027] [Fig.l] illustrates a sectional view of the electric fluid pump 1, in particular an oil pump for supplying a clutch actuator, a gearbox actuator, a lubrication system and / or a cooling system of a powertrain configured according to the present invention. The liquid pump 1 has a housing 2 which is generally designated 2 and which has a suction port 3 and a discharge port 4. An electric motor 5 is arranged in the housing 2 and comprises a stator 6 and an internal rotor 7. The rotor 7 is received inside the stator 6 to leave an annular gap 8 and can be rotated about the axis of rotation X.

[0028] A pump unit which is generally designated by 17 in [Fig.l] and [Fig.2] and which has a suction inlet 11 in fluid communication with a suction port 3 of the casing 2 and a discharge outlet 12 in fluid communication with a discharge port 4 of the casing 2. The pump unit is driven by the rotor 7 of the electric motor 5 by means of a shaft 10. The pump unit 17 is axially on a first side of the electric motor 5.

[0029] Furthermore, a control unit 13 for driving the electric motor 5 and controlling the operation of the pump is provided in the housing 2. The control unit 13 is connected to an external electrical connector (not shown) and to various terminals for control and sensor signals. The control unit 13 is axially on a second side of the electric motor 5 opposite the pump unit 17.

[0030] In an embodiment as shown in [Fig.l] and [Fig.2], the housing 2 has a partition wall 14 which extends substantially transversely to the axis of rotation X and is adjacent to the rotor 7. The partition wall 14 delimits a wet interior space 24, which is filled with the liquid to be pumped during operation, of the housing 2, in which the rotor 7 consequently operates in a wet state. The control unit 13 is mounted in the housing 2 on the dry side 27 of the partition wall 14 remote from the rotor 7.

[0031] In another embodiment not shown, the control unit 13 is inside the housing 2. In other words, the control unit 13 is in a humid interior space inside the housing 2. The electric motor 5 and the control unit 13 are in fluid communication with the pump unit. In this embodiment, there is no partition wall 14 or the partition wall 14 has at least one opening for fluid circulation.

[0032] A temperature sensor (not shown) may be attached to the control unit 13. Attaching the temperature sensor to the control unit 13 is more economical than external sensors.

[0033] The rotor 7 has a tubular main body 18. The rotor 7 has a part 19 for receiving the shaft 10 arranged radially inwardly relative to the tubular main body 18. As shown in [Fig.3] and [Fig.4], the impeller 15 has four blades 20 used for pumping the fluid. Each of the blades 20 is mechanically connected between the portion 19 receiving the rotor shaft 10 and the tubular main body 18. The blades 20 have a helical shape. As a variant not shown, the blades 20 may be straight bars.

[0034] The part 19, the blades 20 and the tubular body 18 are formed integrally with each other from an injection-molded plastic material.

[0035] A stack of rotor laminations generally designated 21 is mounted on the radially outer ends of the tubular main body 18. It can be obtained by an overmolding process. The stack 21 consists of a plurality of laminated stamped parts. The stack 21 of laminated stamped parts creates a plurality of magnet cavities 22. Each magnet cavity 22 extends axially to accommodate a permanent magnet 23. Each magnet cavity 22 has a cooling gap 25 after mounting the permanent magnets 23. The cooling gaps 25 of the magnet cavities 22 are on both sides of the permanent magnets 23.

[0036] [Fig. 5] shows the stator 6 of the electric motor 5 comprising a plurality of metal stator laminations. The plurality of metal stator laminations creates a stator stack designated by 28. The stator stack 28 has slots for carrying the stator windings 30. The slots are distributed circumferentially in the stator stack 28 and carry the stator windings 30. The stator stack 28 has radially inner ends 29 adjoining the annular gap 8, a free space 26 being present between two adjacent stator windings 30 and allowing fluid communication with the annular gap 8.

[0037] Said tubular main body 18 allows the axial flow of the fluid. The annular gap 8 between the stator 6 and the rotor 7 also allows the flow of fluid around the rotor 7.

[0038] During operation, the fluid enters the electric fluid pump through the suction port 3. Then the fluid bypasses the pump unit 17 via a channel not further defined. From this channel, the fluid is sucked in by the impeller 15. Then, the fluid flows to the rear suction inlet 3 of the pump unit 17. The fluid is sucked into the pump unit 17. The fluid can only reach the discharge port 4 by being pumped by the pump unit 17. There is absolutely no direct connection between the wet-operated electric motor 5 and the discharge port 4.

[0039] As shown in [Fig.3], the fluid flows through a cooling gap- 25 of the magnet cavity 22 on either side of the permanent magnet 23. The cooling gap 25 extends axially along the magnet cavity 22.

[0040] In the present arrangement of the electric motor-driven fluid pump 1, the fluid flow path takes into account the cooling of the parts comprising the stator, the rotor, the shaft, the control unit and also the motor terminals associated with the control circuit.

Claims

Claims

1. Electric fluid pump (1), in particular an oil pump for supplying a clutch actuator, a gearbox actuator, a lubrication system and / or a cooling system of a drive train, comprising a housing (2) having at least one suction port (3) and at least one discharge port (4), an electric motor (5) having a stator (6) and a rotor (7) which is received inside the stator (6) with an annular gap (8) and is rotatable about an axis of rotation (X), a pump unit (17) which is in driving connection with the rotor (7) via a rotor shaft (10) and which has a suction inlet (11) in fluid communication with the suction port (3) and a discharge outlet (12) in fluid communication with the discharge port (4), a control unit (13) serving to the electric motor drive (5),characterized in that the rotor (7) incorporates a wheel (15) in order to force the fluid flow to circulate at least axially inside the rotor (7), around the rotor (7) in the annular gap (8) and axially between the control unit (13) and the electric motor (5).,

2. An electric fluid pump (1) according to claim 1, wherein the housing (2) comprises a partition wall (14) which extends substantially transversely to the axis of rotation (X) and is axially between the control unit (13) which is in a dry zone and the electric motor (5) which is in a wet zone in fluid communication with the pump unit (17).

3. An electric fluid pump (1) according to claim 1, wherein the electric motor (5) and the control unit (13) are in fluid communication with the pump unit (17).

4. Electric fluid pump (1) according to claim 1, characterized in that the rotor (7) comprises a tubular main body (18) and a part (19) receiving the rotor shaft (10).

5. Electric fluid pump (1) according to claim 4, characterized in that the impeller (15) has several blades (20) constituting a mechanical connection between the part (19) receiving the rotor shaft (10) and the tubular main body (18).

6. Electric fluid pump (1) according to claim 5, characterized in that the blades (20) have a helical shape or straight bars.

7. Electric fluid pump (1) according to one of claims 4 to 6, ca- characterized in that the part (19) receiving the rotor shaft (10), the blades (20) and the tubular main body (18) are formed integrally with each other from a plastic material.

8. An electric fluid pump (1) according to one of claims 4 to 7, characterized in that the rotor (5) comprises a stack (21) of rotor laminations which are received on the tubular main body (18) and have a plurality of magnet cavities (22) and a plurality of permanent magnets (23) which are received in the magnet cavities (22).

9. Electric fluid pump (1) according to claim 8, characterized in that the fluid flow is able to circulate in the magnet cavities (22).

10. Electric fluid pump (1) according to one of claims 4 to 7, characterized in that the tubular main body (18) of the rotor (7) is made of plastic material in which magnetic particles are incorporated.

11. Electric fluid pump (1) according to one of the preceding claims, characterized in that a temperature sensor is attached to the control unit (13).

12. Electric fluid pump (1) according to one of the preceding claims, characterized in that the stator (6) of the electric motor (5) comprises a plurality of stator metal laminations which carry stator windings (30) and have radially inner ends (29) adjoining the annular gap (8), a free space (26) being present between two adjacent stator windings (30) and allowing fluid communication with the annular gap (8).

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