WO2019233600A1

WO2019233600A1 - Electric coolant pump

Info

Publication number: WO2019233600A1
Application number: PCT/EP2018/065170
Authority: WO
Inventors: Martin Helmis
Original assignee: Pierburg Pump Technology Gmbh
Priority date: 2018-06-08
Filing date: 2018-06-08
Publication date: 2019-12-12
Also published as: JP7168689B2; JP2021526609A; CN112262262A; US11808267B2; CN112262262B; EP3803131A1; US20210239121A1

Abstract

Electric coolant pump (10) comprising a pump housing (12) defining a pumping chamber (20) being filled with a coolant during pump operation, with radially Inner pump Inlet (22), a radially outer pump outlet (24) and a pump volute (26) extending from downstream of the pump inlet (22) to the pump outlet (24), and a motor chamber (28) being fluidically separated from the pumping chamber (20) by a separation sidewal! (18) extending substantially in a radial plane, an electric motor (30) with a rotatable motor rotor (32), a static motor stator (34) with a single compact stator coil arrangement (50) being arranged laterally with respect to the motor rotor (32) in the motor chamber (28) and a motor electronics (36) being arranged in the motor chamber (28) for energizing the stator coil arrangement (50), and a pump wheel (58) being arranged in the pumping chamber (20) and being co-rotatably connected with the motor rotor (32), wherein the stator coil arrangement (50) Is arranged axlally adjacent to a volute cooling sector (60) of the pump volute (26) and is in thermal contact with a cooling section (62) of the separation sidewall (18) being defined by the volute cooling sector (60) and wherein the volute cooling sector (60) of the pump volute extends over a volute angle (A) of 120° starting at the pump outlet (24).

Description

Electric coolant pump The invention is directed to an electric coolant pump, preferably to an electric coolant pump for a motor vehicle.

A motor vehicle electric coolant pump Is typically provided to circulate a coolant of a motor vehicle cooling circuit, primarily for cooling an Internal combustion engine of the motor vehicle. To avoid damage of the internal combustion engine, the electric coolant pump has to be reliable and failsafe. Since the available space In a motor vehicle engine compartment Is limited, electric coolant pumps are typically designed very compact. Electric coolant pumps can be, for example, provided with an electric motor with a compact stator coll arrangement requiring only a small space for the motor stator. However, the compact stator coll arrangement hast to be driven with a high drive energy density to allow a high mechanical pump performance. The high energy density In the stator coil arrangement generates significant heat caused by resistive heating. The generated heat has to be efficiently dissipated to avoid an overheating of the electric motor, in particular of a heat sensitive motor electronics, and to allow a high motor efficiency.

An electric coolant pump for a motor vehicle Is disclosed, for example, In WO 2017/220119 Al. The coolant pump is provided with a pump housing which defines a pumping chamber and a motor chamber. The pumping chamber Is filled with the coolant and comprises a radially inner pump Inlet, a radially outer pump outlet and a pump volute extending from downstream of the pump Inlet to the pump outlet. The motor chamber Is fluldically separated from the pumping chamber by a separation sidewall extending substantially In a radial plane. The coolant pump Is provided with an electric motor with a rotatable motor rotor, a motor stator with a compact stator coil arrangement and a motor electronics for energizing the stator coil arrangement. The stator coil arrangement is defined by a single stator coil being arranged laterally with respect to the motor rotor. The motor stator and the motor electronics are arranged in the dry motor chamber. The coolant pump comprises a pump wheel which is arranged in the pumping chamber and which is co-rotatably connected with the motor rotor by an axially extending rotor shaft so that the pump wheel is driven by the electric motor. The stator coil arrangement is provided axially adjacent to a volute cooling sector of the pump volute. The stator coil arrangement is in thermal contact with the separation sidewall, in particular with a cooling section of the separation sidewall being defined by the volute cooling sector, so that the stator coil arrangement is cooled by the coolant being pumped through the pump volute and flowing along the sidewall cooling section. However, the sidewall cooling section area Is relatively small. As a result, at least parts of the stator coil arrangement being located radially further outside with respect to the volute cooling sector are not cooled efficiently so that this stator coil arrangement heats up relatively fast. The higher the temperature of the stator coil arrangement is, the lower Is its electromagnetic efficiency. As a result, the stator coil arrangement has to be driven with higher drive energy to achieve a predefined motor performance, which in turn increases the heat being generated in the stator coll arrangement. In addition, the higher drive energy causes additional heating of the motor electronics providing the drive energy to the stator coil arrangement. As a result, the electric motor and, In particular, the motor electronics can overheat which can cause a malfunction or even a failure of the electric coolant pump. It is an object of the invention to provide a compact and reliable electric coolant pump with a high pump performance. This object is achieved with an electric coolant pump with the features of claim 1.

The electric coolant pump according to the invention is provided with a pump housing which defines a pumping chamber and a motor chamber, both being fluidlcally separated from each other by a separation sidewall extending substantially In a radial plane. The pumping chamber Is filled with a liquid coolant during pump operation and comprises a radially inner pump inlet and a radially outer pump outlet. Preferably, the pump Inlet substantially extends In an axial motor direction and the pump outlet substantially extends in a radial plane so that the pump Inlet extends substantially perpendicular with respect to the pump outlet. The pump Inlet and the pump outlet are fluidlcally connected by a pump volute extending from downstream of the pump inlet to the pump outlet in a radial plane. The flow cross section of the pump volute increases from the pump inlet to the pump outlet to provide an efficient coolant discharge.

The electric coolant pump comprises an electric motor with a rotatable motor rotor, a static motor stator and a motor electronics for energizing the stator coil arrangement. The rotatable motor rotor Is magnetically driven by the motor stator. Preferably, the motor rotor is permanent- magnetic so that no wear- prone sliding contacts are required to electromagnetlcally magnetize the motor rotor. The electric components, I.e. the motor electronics and the electromagnetic motor stator, are sensitive to the coolant and, as a result, are arranged in the dry motor chamber.

The motor stator Is provided with a single compact stator coil arrangement which can be defined by a single stator coil or can comprise several stator coils. In any case, all stator coils of the stator coil arrangement are arranged concentrated in a compact cluster, I.e. all stator colls are arranged in direct vicinity to each other. The stator coil arrangement is arranged laterally with respect to the motor rotor so that all stator coils of the stator coil arrangement are arranged on the same side of the motor rotor. The stator coils are not distributed along the circumference of the motor rotor. As a result, only a small space Is required for the stator coil arrangement.

The electric coolant pump Is provided with a pump wheel being co- rotatably connected with the motor rotor so that the pump wheel Is driven by the electric motor. The pump wheel can be provided Integrally with the motor rotor or, alternatively, can be co-rotatably connected with the motor rotor, for example, by a rotor shaft. The pump wheel Is arranged In the pumping chamber for pumping the coolant from the pump inlet through the pump volute to the pump outlet. Preferably, the pump wheel Is located in the radial center of the pump volute so that the coolant entering the pumping chamber via the preferably axial pump inlet flows substantially axially against the pump wheel and is accelerated radially outwardly by the rotating pump wheel.

According to the invention, the stator coil arrangement is located axially adjacent to a volute cooling sector of the pump volute. The volute cooling sector defines a sidewall cooling section which axially separates the volute cooling sector from the motor chamber. The sidewall cooling section is cooled by the coolant flowing through the volute cooling sector. The stator coll arrangement is in thermal contact with the sidewall cooling section, i.e. there is no air gap between the stator coil arrangement and the sidewall cooling section. As a result, the stator coil arrangement can be cooled by the coolant being pumped through the pump volute.

The volute cooling sector extends over a volute angle of 120° starting at the pump outlet, i.e. the volute cooling sector Is located at the pump outlet. As a result, the volute cooling sector defines a relatively large sidewall cooling section area because the flow cross section of the pump volute Increases from the pump inlet to the pump outlet. This allows an efficient cooling of the entire stator coil arrangement which reduces the temperature of stator coll arrangement and the heat being dissipated by the stator coll arrangement Into the motor chamber.

The reduced stator coll arrangement temperature Improves the electric conductivity and, as a result, the electromagnetic efficiency of the stator coll arrangement so that lower driving energy is required to achieve a predetermined pump performance. This reduces the waste heat generation in the motor electronics. The reduced waste heat generation in the motor electronics and the reduced heat dissipation of the stator coil arrangement into the motor chamber avoid an overheating of the motor electronics. In addition, the Improved electromagnetic efficiency allows a higher pump performance for predetermined driving energy. As a result, the electric coolant pump according to the Invention can reliably provide a high mechanical pump performance.

Beside of the higher electric conductivity of the stator coil arrangement, the efficient cooling of the stator coll arrangement also allows dissipating more heat via the sidewall cooling section Into the coolant so that more heat can be generated In the stator coll arrangement without overheating the stator coll arrangement. As a result, the efficient cooling of the stator coll arrangement allows reducing the coll wire cross section of the stator coll arrangement without losing motor efficiency and without overheating the stator coll arrangement. This allows a more compact stator coll arrangement and, as a result, a compact electric motor.

Preferably, the stator coil arrangement is defined by a single stator coll being arranged laterally and satelllte-IIke with respect to the motor rotor, The single stator coll allows a very compact realization of the stator coll arrangement and, as a result, of the electric coolant pump. In addition, the single stator coil can be easily arranged axially adjacent to and in thermal contact with the sidewall cooling section.

In a preferred embodiment of the Invention, the thermal contact between the stator coll arrangement and the sidewall cooling section Is provided by a heat transfer element being arranged axially between and In direct contact with the sidewall cooling section and the stator coll arrangement. The heat transfer element is provided with a high thermal conductivity of at least 1 W/(m-K). Preferably, the heat transfer element Is relatively flexible so that the heat transfer element can be adapted to the contour of the stator coil arrangement. This allows a large contact area between the heat transfer element and the stator coll arrangement and, as a result, allows very efficient heat dissipation from the stator coll arrangement via the heat transfer element and the sidewall cooling section Into the coolant and, as a result, an efficient cooling of the stator coll arrangement.

Preferably, at least the cooling section of the separation sidewall Is made of a material with a high thermal conductivity, for example made of aluminum. Preferably, the thermal conductivity of the sidewall cooling section material Is higher than 10 W/(m-K), but at least, the thermal conductivity is higher than that of plastic materials. This allows an efficient heat transfer from the stator coll arrangement via the sidewall cooling section Into the coolant and, as a result, an efficient cooling of the stator coll arrangement.

Since significant heat is generated In the motor electronics during the motor operation, sufficient cooling of the motor electronics is required to avoid a malfunction or damage of the motor electronics and, as a result, to avoid a failure of the electric coolant pump. In a preferred embodiment of the Invention, the motor electronics Is provided In thermal contact with the separation sidewall so that the motor electronics Is cooled by the coolant being pumped through the coolant pump. This provides a reliable electric motor and, as a result, a reliable electric coolant pump. Preferably, the geometry of the motor electronics is adapted to the geometry of the pump volute so that the entire motor electronics can be provided in thermal contact with the separation sidewall.

Preferably, the motor rotor is arranged In a rotor chamber being fluldlcally separated from the motor chamber by a separation can. The separation can extends through the air gap between the motor rotor and the motor stator and Is made of a material which is permeable for the magnetic field generated by the motor stator. Since the rotor chamber Is fluldlcally separated from the motor chamber, the rotor chamber does not have to be sealed against the pumping chamber. This allows a simple co-rotatable connection of the motor rotor with the pump wheel not requiring any complex sealing elements which are expensive and liable to wear.

An embodiment of the invention Is described with reference to the enclosed drawings, wherein

figure 1 shows a schematic partially sectioned side view of an electric coolant pump according to the Invention,

figure 2 shows a schematic partially sectioned top view of an electric motor of the coolant pump of figure 1, and

figure 3 shows a schematic top view of a pumping chamber cover of the coolant pump of figure 1. The electric coolant pump 10 comprises a multi-part pump housing 12 with a pumping chamber cover element 14, a motor chamber cover element 16 and a separation sidewall 18 substantially extending In a radial plane. In the present embodiment of the Invention, the separation sidewall 18 Is made of a material with a high thermal conductivity, for example made of aluminum. The pumping chamber cover element 14 and the separation sidewall 18 define a pumping chamber 20 being filled with a coolant during pump operation. The pumping chamber 20 comprises a radially inner pump inlet 22, a radially outer pump outlet 24 and a pump volute 26 extending from downstream of the pump inlet 22 to the pump outlet 24 In a radial plane. The pump Inlet 22 extends substantially In an axial motor direction and the pump outlet 24 extends substantially in a radial plane so that the pump Inlet 22 Is arranged substantially perpendicular with respect to the pump outlet 24. The flow cross section of the pump volute 26 increases from the pump inlet 22 to the pump outlet 24. The motor chamber cover element 16 and the separation sidewall 18 define a motor chamber 28 being fluidlcally separated from the pumping chamber 20 by the separation sidewall 18.

The coolant pump 10 comprises an electric motor 30 with a rotatable permanent-magnetic motor rotor 32, a static electromagnetic motor stator 34 and a motor electronics 36 for energizing the motor stator 34. The motor rotor 32 Is located In a rotor chamber 38 being fluidlcally separated from the motor chamber 28 by a separation can 40. The motor stator 34 and the motor electronics 36 are arranged In the dry motor chamber 28.

The motor rotor 32 Is co-rotatably fixed to a rotor shaft 42 being rotatable about an axis of rotation R. The rotor shaft 42 is rotatably supported in the separation can 40 and In the separation sidewall 18 by two suitable shaft bearings 44,46. The rotor shaft 42 axially extends from the rotor chamber 38 Into the pumping chamber 20. The motor stator 34 Is provided with a laminated stator body 48 and with a single electromagnetic stator coll arrangement 50. In the present embodiment of the Invention, the stator coil arrangement 50 Is defined by a single stator coll 52 being arranged laterally and satelllte-like with respect to the motor rotor 32. The stator coll arrangement 50 Is electrically connected with and energized by the motor electronics 36. The stator coll arrangement 50 and the motor electronics 36 are arranged diametrically opposite with respect to the motor rotor 32. The motor electronics 36 comprises several power semiconductors 54 being arranged on a printed circuit board 56. In the present embodiment of the Invention, the printed circuit board 56 of the motor electronics 36 Is In direct thermal contact with the separation sidewall 18 so that the motor electronics 36 Is cooled by the coolant being pumped through the pump volute 26.

The coolant pump 10 comprises a pump wheel 58 being located In the pumping chamber 20 for pumping the coolant from the pump Inlet 22 through the pump volute 26 to the pump outlet 24. The pump wheel 58 Is co-rotatably connected with the rotor shaft 42 so that the pump wheel 58 Is driven by the electric motor 30. The pump wheel 58 Is arranged within the pumping chamber 20 In such a way that the coolant entering the pumping chamber 20 via the pump Inlet 22 flows substantially axially against the pump wheel 58 and Is accelerated radially outwardly by the rotating pump wheel 58.

The stator coll arrangement 50 Is located axially adjacent to a volute cooling sector 60 of the pump volute 26. The volute cooling sector 60 extends over a volute angle A = 120° starting at the pump outlet 24 and running in a pump-ln let-facing circumferential direction of the pump volute 26. The volute cooling sector 60 defines a sidewall cooling section 62 which axially limits the volute cooling sector 60 towards the motor chamber 28. The sidewall cooling section 62 is cooled by the coolant flowing through the volute cooling sector 60.

The stator coll arrangement 50 Is laterally positioned within the lateral extent of the sidewall cooling section 62. A heat transfer element 64 Is arranged axially between the sidewall cooling section 62 and the stator coll arrangement 50. The heat transfer element 64 Is made of a flexible material with a high thermal conductivity. In the present embodiment of the invention, the heat transfer element 64 Is a commercially available thermal pad with a thermal conductivity of a least 1 W/(m-K). The heat transfer element 64 is in direct large-area contact with the sidewall cooling section 62 and the stator coll arrangement 50 so that the heat transfer element 64 provides a thermal contact between the stator coll arrangement 50 and the sidewall cooling section 62. As a result, the stator coll arrangement 50 is efficiently cooled by the coolant being pumped through the pump volute 20 during pump operation.

Claims

C L A I M S

1. Electric coolant pump (10) comprising

a pump housing (12) defining

a pumping chamber (20) being filled with a coolant during pump operation, with

a radially inner pump Inlet (22),

a radially outer pump outlet (24) and

a pump volute (26) extending from downstream of the pump Inlet (22) to the pump outlet (24), and

a motor chamber (28) being fluidically separated from the pumping chamber (20) by a separation sidewall (18) extending substantially In a radial plane,

an electric motor (30) with

a rotatable motor rotor (32),

a static motor stator (34) with a single compact stator coll arrangement (50) being arranged laterally with respect to the motor rotor (32) in the motor chamber (28) and

a motor electronics (36) being arranged In the motor chamber (28) for energizing the stator coll arrangement (50), and a pump wheel (58) being arranged in the pumping chamber (20) and being co-rotatably connected with the motor rotor (32), wherein the stator coll arrangement (50) Is arranged axially adjacent to a volute cooling sector (60) of the pump volute (26) and Is in thermal contact with a cooling section (62) of the separation sidewall (18) being defined by the volute cooling sector (60) and wherein the volute cooling sector (60) of the pump volute extends over a volute angle (A) of 120° starting at the pump outlet (24).

2. Electric coolant pump (10) according to claim 1, wherein the stator coll arrangement (50) Is defined by a single stator coll (52).

3. Electric coolant pump (10) according to any preceding claim, wherein the thermal contact between the stator coll arrangement (50) and the sidewall cooling section (62) Is provided by a heat transfer element (64) being arranged axially between and being In direct contact with the sidewall cooling section (62) and the stator coll arrangement (50).

4. Electric coolant pump (10) according to any preceding claim, wherein the sidewall cooling section (62) Is made of a material with a high thermal conductivity.

Electric coolant pump (10) according to any preceding claim, wherein the motor electronics (36) Is provided In thermal contact with the separation sidewall (18).

5. Electric coolant pump (10) according to any preceding claim, wherein the motor rotor (32) Is arranged In a rotor chamber (38) being fluid!cally separated from the motor chamber (28) by a separation can (40).