WO2021170327A1

WO2021170327A1 - Thermally optimised coolant pump

Info

Publication number: WO2021170327A1
Application number: PCT/EP2021/051676
Authority: WO
Inventors: Paul Michael Ludwig; Franz Pawellek
Original assignee: Nidec Gpm Gmbh
Priority date: 2020-02-28
Filing date: 2021-01-26
Publication date: 2021-09-02
Also published as: DE102020105337A1; DE102020105337B4

Abstract

The invention relates to a thermally optimised coolant pump. The electrical coolant pump is characterised in that a drive housing (2) has a central bearing holder section (25), in which a shaft bearing (52) is accommodated, and a heat dissipation wall (6) that is separate from the drive housing (2) is provided, which separates an electric motor (3) from a pump housing (1), and is in thermal contact with a power electronics system (30). The heat dissipation wall (6) is exposed to an open cross-sectional area of a pump chamber (10) and to an open cross-sectional area of a spiral housing section (14). In particular, the heat dissipation wall (6) has a lower area-related heat storage capacity than the bearing holder section (25), the spiral housing section (14) and the flange sections (12, 21).

Description

description

Thermally optimized coolant pump

The present invention relates to an electric coolant pump with an optimized construction with regard to thermally critical power electronics of an electric motor.

Due to the flexible control options, electrical coolant pumps are preferred for thermal management of internal combustion engines in vehicle construction. The coolant pump in the engine compartment of a vehicle is exposed to numerous environmental influences, such as temperature fluctuations, moisture and dirt. Therefore, coolant pumps including the electric drive are designed in an externally closed or encapsulated design that is sealed against external influences.

When using an electric motor as a pump motor, it is usually encapsulated together with power electronics in order to protect it from external corrosive influences and contamination during operation. Due to the common encapsulation of the electric motor and the power electronics, the waste heat of the electric motor, which is associated with its power loss, cannot be dissipated by an air flow as in other applications. Part of the waste heat from the electric motor thus flows directly into the electronic components of the power electronics of the coolant pump as heat input.

In the case of a suitable electric pump motor, the power loss is up to about 20% of the electric power, so that in a pump motor with 500 W, such as is used, for example, in a coolant pump of a coolant circuit in a car. In full load operation, depending on the design of the electric motor, a heat input of up to 100 W can occur, which is also generated by the coolant pump the waste heat of the coolant is also absorbed. The field coils of the stator can reach temperatures of up to 200 ° C.

In the prior art, coolant pumps are known which use a heat exchange with the coolant of the internal combustion engine to maintain the permissible operating temperature of the electronic components. The coolant has a much higher coefficient of thermal conductivity of around 0.441 W / mK compared to air with 0.0262W / mK. In addition, it maintains a defined temperature range when the coolant circuit is in operation, whereas the temperature of the air varies greatly depending on the environment, in particular the internal combustion engine, and possibly a movement speed.

Efforts have been made in different constructive configurations to incorporate the power electronics into a heat exchange with the coolant that is conveyed by the coolant pump. During ferry operation, the coolant assumes a setpoint temperature of around 110 ° C, and under particular load conditions can briefly rise to 120 ° C or up to 130 ° C. At a temperature of a few tens of degrees above this, damage can already occur in electronic components. As long as a temperature profile of the power electronics remains closely linked to the temperature profile of the coolant, overheating of the power electronics can be prevented. For this, however, an efficient heat transfer must be created so that only a small temperature difference between the power electronics and the coolant arises in load conditions.

An example from the prior art that addresses the problem of heat exchange between power electronics of a coolant pump and the required coolant flow is described in DE 10 2015 114 783 A1. The commonly owned patent application describes an electric coolant pump in which an ECU is located on a side of the pump housing opposite the electric motor and is located within a donut-shaped cover or ring around the central inlet. The front side of the pump chamber facing the ECU is made of a pump cover Completed material with high thermal conductivity, which should allow an improved heat exchange between the coolant in the pump chamber and the ECU. It is intended to manufacture the pump cover as a solid, milled aluminum part, which has better thermal conductivity than a cast alloy for a volute casing.

The patent application DE 10 2018 104 015 A1 by the same applicant describes a coolant pump with an optimized bearing arrangement and an improved heat balance. A coolant-lubricated slide bearing is accommodated in a carrier flange. A cylindrical part of the carrier flange extends to an electric motor and a flange-shaped separating section extends radially to a peripheral wall of a motor housing. An annular control unit is arranged in a motor chamber, with heat dissipation being provided for the control unit via the support flange. In order to be able to absorb the forces of the shaft bearing, it is necessary to dimension the carrier flange correspondingly massive.

The Japanese patent application JP 2017 110 593 A describes an electric circulation pump with a motor chamber and a pump chamber, which are separated from one another by a metallic partition wall of the housing. In the area of the spiral housing on the side of the motor chamber, an electronic circuit board is arranged on the partition, which can transfer waste heat to the conveying medium by means of a heat exchanger.

The publication DE 11 2013 003 549 T5 describes an electric canned water pump with a wet rotor motor. A so-called wet liner or a containment can separates a fluid-carrying area, in which the rotor is arranged, from the stator. A so-called electronic donut, i.e. control electronics on a ring-shaped printed circuit board, is arranged directly next to the stator and is consequently exposed to its waste heat. However, the ring-shaped printed circuit board is arranged around the pump impeller and is cooled by the wet sleeve or the can. The can runs through the air gap between the rotor and the stator. Such cans are generally as thin as possible designed to keep a reduction in the electromotive efficiency at the air gap as low as possible. The use of the can causes an enlargement of the air gap and the material in the air gap represents an impairment of the magnetic flux between the field coils of the stator and the rotor. A further reduction in efficiency is caused by splashing losses of the rotor, which moves in the fluid. In addition to the poorer efficiency, wet-rotor motors have the cost disadvantage that the rotor and the stator have to be individually tailored to the geometry of the containment shell, i.e. the geometry of a pump model, and cannot be obtained cheaply as a standardized unit like a dry-running electric motor.

One object of the present invention is to create an alternative structure for an electric coolant pump with a dry-running electric motor which provides improved temperature control of power electronics.

The object is achieved by an electric coolant pump with the features of main claim 1.

The electrical coolant pump is characterized in that a drive housing has a central bearing receiving section in which a shaft bearing is received; and a separate heat dissipation wall from the drive housing is also provided, which separates the electric motor from the pump housing and is in thermal contact with the power electronics. The heat dissipation wall is exposed to an open cross-sectional area of the pump chamber and an open cross-sectional area of the volute casing section. In particular, the heat dissipation wall has a lower surface-related heat storage capacity than the bearing receiving section, the spiral housing section and the flange sections.

The invention provides for the first time a separate wall to delimit a liquid-carrying area, through which a shaft of a dry-running drive passes, and which is neither an integral part of the drive housing or the pump housing, nor a supporting function in the Housing construction met. The invention further provides for the first time in a cross section of the pump impeller a separate wall for delimiting the pump chamber, which wall has a lower surface-related heat storage capacity than adjoining housing sections.

In the most general form of the invention, the structure of the pump housing does not follow a common design approach which provides for an integration of elements to achieve a smaller number of components and seals. Instead, the structure of the pump housing follows an approach of assigning a function to individual elements or sections of the housing and, if necessary, removing them from a conventional design and designing them with a quality optimized for the assigned function.

Furthermore, with regard to thermal optimization of a housing construction for electrical drive components, there is the general knowledge that improved heat dissipation from the electrical drive can be achieved through the best possible specific thermal conductivity (λ = m / K) of a housing material. This property is known, for example, from aluminum heat sinks. According to this general knowledge, it is sufficient to design solid load-bearing elements, i.e. in particular without insulating cavities, and to manufacture them from aluminum or an aluminum die-cast alloy.

In the case of a delivery flow, which usually provides a very large mass flow with a high heat storage number s [kJ / m ³ K] for heat removal and convection for heat absorption at an interface, further factors come into play.

In contrast to this, the invention is based on the knowledge that improved dynamic heat dissipation can be achieved in operating states of increasing electrical power, in particular through a lower thermal resistance in a heat conduction path between the heat source and the conveying flow in a housing. Such thermal resistance does not only depend on one specific thermal conductivity of the material, but also on an area-related heat storage capacity (χ = c / A) of the housing, which relates to a specific heat storage capacity c [kJ / kg K] of the housing mass within a heat conduction path based on a cross-sectional area A of a heat flow. As long as sufficient heat absorption and heat dissipation is provided in the form of the mass flow on one side, heat storage capacities of the housing within the heat conduction path represent inertia as a component of the thermal resistance, i.e. delaying intermediate storage in a dynamic heat flow.

Housings are usually manufactured as cast parts, the complex shape of which combines various elements and points for delimitation, accommodation, fastening, etc. in an integral body. With regard to pumps, this saves components and sealing points. Housing walls, which are used to delimit a liquid-carrying area of a pump and have a breakthrough for a shaft, are always made solid due to the casting technology and have functional shaped sections for fastening or receiving a seal or a bearing or other supporting function. Furthermore, these housing walls are conventionally made of the same material as surrounding housing walls with a different function.

According to the invention, the housing is divided into separate sections. The drive housing takes on the load-bearing functions for accommodating the electric motor and for fixing the shaft. The separately designed heat dissipation wall takes on the function of a delimitation between the liquid-carrying area in the pump housing and the drive housing. As a result, there is indeed a component that requires an additional seal around a shaft breakthrough. However, this makes it possible to withdraw the heat dissipation wall from a casting process and to equip it with its own properties. According to the invention, a different nature of the heat dissipation wall in contrast to the other adjacent housing sections is designed in such a way that it has a lower area-specific heat storage capacity (χ = c / A). The reduced heat storage capacity ensures a heat source that is in thermal contact with the heat dissipation wall, a faster heat dissipation.

The invention also provides, as a heat source on the part of the electric drive, to put the power electronics for a brushless electric motor, which includes field effect transistors and capacitors with a high power consumption, in thermal contact with the heat dissipation wall. This provides faster heat dissipation of dynamic heat flows from the power dissipation of the power electronics, so that with increasing load conditions, waste heat is less temporarily stored on the part of the housing, but rather heat can be absorbed and dissipated as directly as possible through the conveying flow.

Advantageous further developments of the invention are the subject of the dependent claims.

According to one aspect of the invention, the heat dissipating wall can have a smaller wall thickness than the bearing receiving section, the spiral housing section and the flange sections. A smaller wall thickness is the easiest way to shorten the length of the heat dissipation section, i.e. to reduce the area-related mass and thus also the area-related heat storage capacity of the heat dissipation wall within a heat conduction section.

According to one aspect of the invention, the heat dissipation wall can be designed as a metal sheet with a wall thickness of 0.2 to 1.5 mm. According to the conventional expectations of the construction of a housing wall to delimit a pressure side of a pump over an entire cross section of a pump housing, such a thin metal sheet would be unsuitable, especially in the present case of a flat extension without stiffening structures. The design of the drive housing according to the invention, on which a flange section and a bearing receiving section arranged centrally therein with a load-bearing function are formed, only enables the use of such a thin metal sheet from a structural point of view. The thin one Execution of the wall thickness extends a suitable choice of materials to metals that have a lower specific thermal conductivity than aluminum. For example, instead of an aluminum sheet, a stainless steel sheet or steel sheet that is protected against corrosion can be used, which due to the small wall thickness still has a lower area-related heat storage capacity than a comparatively solid housing wall made of a cast aluminum alloy or as a milled aluminum part.

According to one aspect of the invention, the heat cablcit wall can extend essentially flat in an axial region between the flange section of the pump housing and the flange section of the drive housing. A planar extension without stiffening structures is structurally made possible by the design of the drive housing according to the invention, on which a flange section and a bearing receiving section with a load-bearing function arranged centrally therein are formed. A flat heat dissipation wall does not contain any flow obstacles on the part of the volute casing or the rear pump chamber behind the pump impeller.

According to one aspect of the invention, the heat dissipating wall can be fixed in a flange plane between the flange section of the pump housing and the flange section of the drive housing. With this configuration, an external fixing and sealing of the heat dissipating wall is structurally simplified by using existing fastening structures.

According to one aspect of the invention, the heat dissipation wall can be in direct thermal contact with a surface of a rear side of a circuit board of the power electronics. This configuration represents an area-optimized thermal connection of the power electronics. For this purpose, for example, thermal paste can be applied to support full-area contact during assembly.

According to one aspect of the invention, at least one metallized surface through which a thermal contact can be arranged on a rear side of a printed circuit board is provided between the heat dissipation wall and the back of the circuit board. On the part of the power electronics, this embodiment represents a means with optimized thermal conductivity for the thermal connection of the printed circuit board. According to one aspect of the invention, the

Power electronics, at least one metallized hole can be arranged, which extends from a rear side through the printed circuit board to a component side, whereby a thermal contact between the heat dissipation wall and an electrical component of the power electronics is established via the at least one metallized hole. On the part of the power electronics, this embodiment represents a means with optimized thermal conductivity, by means of which a thermal connection of a transistor, a capacitor, or the like is established on the component side of the printed circuit board that is opposite the heat dissipation wall. According to one aspect of the invention, in a printed circuit board

Power electronics can be arranged at least one opening, and a metallic component extend from a rear side through the opening to a component side of the circuit board, whereby a thermal contact is provided between the heat dissipation wall and an electrical component of the power electronics via the metallic component. This embodiment represents a means with optimized thermal conductivity, by means of which a thermal connection of a transistor, a capacitor, or the like is established on the component side of the printed circuit board that is opposite the heat dissipation wall. According to one aspect of the invention, the heat dissipation wall can be pronounced

Have sections that are in thermal contact with a rear side of a circuit board of the power electronics. This variant provides for the first time on the part of the heat dissipation wall designs of the same, which in sections, for example in areas of transistors, a capacitor, or the like, establish a direct thermal connection of the circuit board to the heat dissipation wall. According to one aspect of the invention, the heat dissipation wall can have a pronounced section and an opening can be arranged in a circuit board of the power electronics, the pronounced section extending from a rear side of the circuit board through the opening to a component side of the circuit board, whereby a direct thermal contact between the heat dissipation wall and an electrical component of the power electronics is provided. This preferred variant provides, for the first time, a configuration of the heat dissipation wall that extends through the printed circuit board and thus creates a direct thermal connection of a transistor, capacitor, or the like to the heat dissipation wall.

An embodiment of the invention is explained in more detail below with reference to the drawing. In the drawing show:

1 shows a cross section through a structure of an electric coolant pump according to an embodiment of the invention;

2 shows a perspective top view of the heat dissipating wall in an assembled state of the electric coolant pump according to the embodiment of the invention;

3 shows a perspective top view of the printed circuit board in an assembled state of the electric coolant pump according to the embodiment of FIG

Invention; and FIG. 4 shows a perspective top view into the drive housing with a mounted electric motor of the electric coolant pump according to the embodiment of the invention.

1 shows a cross section through the structure of an electric coolant pump according to an embodiment of the invention. The structure of the electric coolant pump shown in FIG. 1 is essentially divided into a pump assembly and a drive assembly, which are connected in a flange plane. on the side shown on the right is arranged a pump housing 1 which is manufactured as a molded part and integrally comprises a plurality of sections. The pump housing 1 thus comprises a pump chamber 10 in which a pump impeller 4 is rotatably received, and a spiral housing section 14 which surrounds the pump chamber 10 to a radial outlet area of the pump impeller 4. The spiral housing section 14 forms a channel which leads a radially accelerated delivery flow to an outlet which is not visible in the cross section shown. An inlet 11 of the pump housing 1 is designed as a connecting piece which feeds the delivery centrally to the pump impeller 4. The pump housing 1 points to a rear side of the pump chamber 10 and the spiral housing 14, that is to say in the direction of flow behind the

Pump impeller 4, an open side, which is open over an entire cross section of a fluid-carrying area. An open cross-sectional area on the open side of the pump housing 1 is surrounded by a flange section 12. The flange section 12 is used for the mutual fastening of the pump assembly and the drive assembly and has corresponding means, such as bores and threads for a detachable screw connection.

A drive housing 2 is arranged on the side shown on the left. The drive housing 2 comprises a housing wall 23 which encloses an electric motor 3. For this purpose, a receptacle for a stator of the electric motor 3 is formed in the housing wall 23. The electric motor 3 is inserted axially through an open rear side of the drive housing 2. The open rear side is closed by a motor cover 7. The motor cover 7 is made from sheet metal and is fixed by deforming a beaded edge which engages in an undercut which is formed circumferentially on an outer side of the housing wall 23. A seal 72 is arranged between the motor cover 7 and an axial end face of the housing wall 23.

A central bearing receiving section 25 is provided in the drive housing 2 and is connected to the outer housing wall 23 via radial housing webs 22. In the central bearing receiving section 25, a shaft bearing 52 is pressed in, which serves at least for the radial mounting of a shaft 5 and is designed as a roller bearing, a slide bearing or the like. The shaft bearing 52 is not with one illustrated arrangement of shaft seals between the bearing receiving portion 25 and a circumference of the shaft 5 sealed in a liquid-tight manner. The pump impeller 4 is fixed in a rotationally fixed manner on a section of the shaft 5 which is directed towards the pump housing 1. A rotor of the electric motor 3 is fixed in a rotationally fixed manner on a section of the shaft 5 which is directed towards the motor cover 7.

The drive housing 2 has an open side towards the pump housing 1, the open cross section of which extends around the bearing receiving section 25 essentially radially to the housing wall 23. Outside the open cross-section, the drive housing 2 comprises a flange section 21. The flange section 21 serves to fasten the pump assembly and the drive assembly to one another and has corresponding means such as bores for a detachable screw connection. The drive housing 2 is produced as a molded part, which comprises the flange section 21, the housing wall 23, the radial housing webs 22 and the bearing receiving section 25 in an integral manner.

Power electronics 30 with a printed circuit board are arranged in the open cross section of the open side of the drive housing 2. The power electronics 30 are used to control field coils of the electric motor 3 from an electrical power supply. The electric motor 3 is a brushless direct current motor with an external stator and an internal, permanently excited rotor. To provide the electrical power supply, a connector 35 is arranged in the region of the flange section 21 on the drive housing 2, which is electrically connected to the power electronics 30. On a component side of the circuit board that faces the electric motor 3, electrical components (not shown) are arranged. In particular, in a radial area that overlaps with the spiral housing section 14, such electrical components are arranged which have a high electrical power throughput and generate a correspondingly high amount of waste heat, such as transistors or capacitors, for example.

To cool the electrical components, a rear side of the printed circuit board of the power electronics 30 facing the pump housing 1 is provided with a Heat dissipation wall 6 in connection. The heat dissipation wall 6 is provided by a metal sheet which extends through the flange plane between the pump housing 1 and the drive housing 2. The heat dissipation wall 6 delimits the open cross section of the open side of the drive housing 2 from the fluid-conducting, open cross section of the pump chamber 10 and of the spiral housing section 14 in the open side of the pump housing 1. A dry chamber for the electrical drive components in the drive housing 2 is thus ensured. For this purpose, the heat dissipation wall 6 has a bore for the shaft 5 to pass through. The bore encloses an outer circumference of the bearing receiving section 25.

The bearing receiving section 25 further comprises a collar 26 which supports the thin metal sheet of the heat dissipating wall 6 against a delivery pressure in the fluid-carrying region of the pump assembly. An annular groove is worked into the collar 26, in which a seal 65 for sealing between the bearing receiving section 25 and the heat dissipating wall 6 is arranged. A groove is also worked into the flange section 21, in which a seal 62 for sealing between the flange section 21 and the heat dissipating wall 6 is arranged. Likewise, a groove is worked into the flange section 12 of the pump housing 1, in which a seal 61 for sealing the flange section 12 to the heat dissipating wall 6 is arranged.

On an outer edge, the heat dissipation wall 6 has deformation sections 60 which, after deformation, encompass the flange section 21 and thus enable a form-fitting joint connection for independent fixation of the heat dissipation wall 6 on the drive housing 2. The heat dissipation wall 6 extends, in particular in the liquid-carrying region of the pump housing 1, essentially flat in the flange plane in order to avoid flow obstacles in the delivery flow. In the area of the flange section 12 of the pump housing 1, a recess 63 is formed in the heat dissipation wall 6 to provide space for positioning means and contacting means between the power electronics 30 and the connector 35 and for an optional rear-side assembly of the circuit board, for example with an operating voltage of 48 V create. For this purpose, the bead-like formation 63 can also be made larger or wider than shown. 2 shows a top view of the heat dissipation wall 6 from one direction of the pump housing 1. The heat dissipation wall 6 is produced as a stamped sheet metal part which essentially corresponds to an outer contour of the flange section 21 of the drive housing 2 in order to close off the open side in the flange plane.

FIG. 3 shows a plan view of the rear side of the printed circuit board of the power electronics 30, which in this perspective is located below the heat dissipating wall 6 from FIG. 2 in a receptacle in the drive housing 2.

4 is a plan view of the open side of the drive housing 2 and the opened cross section, which is delimited by the heat dissipating wall 6 and sealed by the seal 62. Axial plug connections for mutual alignment and electrical contacting between the electric motor 3 and the power electronics 30 are provided between the radial housing webs 22. Positioning means for alignment and electrical contacting of power electronics 30 are also provided on a socket of connector plug 35 and in a multiple plug connection.

The heat dissipation wall 6 is made of sheet metal with a wall thickness of approximately 1.0 mm. Compared to the wall sections of the mold parts which form the drive housing 2 or the pump housing 1, the heat dissipation wall 6 has a considerably lower mass per unit area. Accordingly, the heat dissipation wall 6, taking into account thermal material properties, such as a specific thermal conductivity of suitable materials for the heat dissipation wall 6 and the drive housing 2 or the pump housing 1, has a lower area-related heat storage capacity. In addition, a heat conduction path from a thermal contact surface to the printed circuit board of the power electronics 30 to an interface of the liquid-carrying area is shorter. Accordingly, an improved heat dissipation according to the invention of waste heat from the power electronics 30 to the conveying flow is provided, which takes place essentially without intermediate storage in a housing section. Alternative embodiments for the configuration of a thermal contact are mentioned below.

In the embodiment of the invention shown, the circuit board of the power electronics 30 and the heat dissipation wall 6 are in large-area contact, which can optionally be additionally ensured by heat conducting agents such as a heat conducting paste, a heat conducting adhesive or a heat conducting pad.

In embodiments of the invention that are not shown, further means for supporting heat dissipation between the power electronics 30 and the heat dissipating wall 6, in particular in relation to the component side of the circuit board, can also be provided. For this purpose, metallic connections are arranged between the rear side of the circuit board and the component side of the circuit board in the power electronics 30. The metallic connections can be provided in the form of a metallized bore, metallized surfaces on the printed circuit board, or metallic elements which reach through an opening in the printed circuit board. Such metallic connections establish thermal contact from the heat dissipation wall 6, through the printed circuit board, to an electrical component, such as a transistor or a capacitor.

In a further embodiment of the invention, not shown, instead of the metallic connections, shaped sections are formed in the heat dissipating wall 6, which are directed towards the printed circuit board of the power electronics 30. The shaped, pronounced sections produce thermal contact to selected areas of the printed circuit board in which electrical components with a high electrical power throughput are arranged.

In a preferred embodiment of the invention, which is not shown, a section which is marked by deformation is formed in the heat dissipating wall 6, which extends through an opening in the circuit board to the component side. The deformed, stamped portion is associated with an electrical component, such as a Transistor or a capacitor in connection. In this refinement, a direct thermal contact is established between the electrical component and the heat dissipating wall 6, which does not require any material boundaries of an intermediate metallic connection. Thus, according to the invention, the most direct possible heat dissipation from the power electronics 30 over the short distance of the small wall thickness of the heat dissipating wall 6 to the conveying flow is achieved in the deformed area of the pronounced section.

It goes without saying that all configurations from different embodiments of the present invention are interchangeable, i.e. can be combined with one another in alternative configurations, and such alternative configurations are also part of this disclosure, as long as a combination does not contradict one another. List of reference symbols:

1 pump housing

2 drive housing

3 electric motor

4 pump impeller 5 shaft

6 heat sink

7 engine cover

10 pump chamber

11 inlet 12 flange section

14 volute casing section

21 flange section

22 housing bridge

23 housing wall 25 bearing receiving section

26 collar

30 Power electronics 35 Connector plugs

52 shaft bearing 60 deformation section

61 Seal

62 Seal 63 molding

65 Seal

72 seal

Claims

Expectations

1. An electric coolant pump, comprising: a pump housing (1) with a spiral housing section (14) which surrounds a pump chamber (10) and leads to an outlet, and with a central inlet (11); wherein the pump housing (1) has an open side which is surrounded by a flange portion (12); a dry-running electric motor (3) which drives a pump impeller (4) in the pump chamber (10) via a shaft (5); and a drive housing (2) in which an electric motor (3) and power electronics (30) are accommodated and which has an open side which is surrounded by a flange section (21); characterized in that the drive housing (2) has a central bearing receiving section (25) in which a shaft bearing (52) is received; a heat dissipation wall (6) separate from the drive housing (2) is provided, which separates the electric motor (3) from the pump housing (1) and is in thermal contact with the power electronics (30); wherein the heat dissipation wall (6) is exposed to an open cross-sectional area of the pump chamber (10) and an open cross-sectional area of the volute casing section (14); and the heat dissipation wall (6) has a lower surface-related heat storage capacity than the bearing housing section (25), the spiral housing section (14) and the flange sections (12, 21).

2. Electric coolant pump according to claim 1, wherein the heat dissipation wall (6) has a smaller wall thickness than that

Bearing receiving section (25), the spiral housing section (14) and the

Has flange sections (12, 21).

3. Electric coolant pump according to claim 1 or 2, wherein the heat dissipation wall is designed as a metal sheet with a wall thickness of 0.5 to 1, 5 mm.

4. Electric coolant pump according to one of the preceding claims, wherein the heat dissipation wall (6) extends essentially flat in an axial region between the flange section (12) of the pump housing (1) and the flange section (21) of the drive housing (2).

5. Electric coolant pump according to one of the preceding claims, wherein the heat dissipation wall (6) in a flange plane between the flange section (12) of the pump housing (1) and the flange section (21) of the drive housing

(2) is fixed.

6. Electric coolant pump according to one of claims 1 to 5, wherein the heat dissipation wall (6) is in direct thermal contact with a surface of a rear side of a circuit board of the power electronics (30).

7. Electric coolant pump according to one of claims 1 to 5, wherein at least one metallized surface is arranged on a rear side of a circuit board of the power electronics (30), through which a thermal contact between the heat dissipation wall (6) and the rear side of the circuit board is provided.

8. Electric coolant pump according to one of claims 1 to 5, wherein in a circuit board of the power electronics (30) at least one metallized bore is arranged, which extends from a rear side through the circuit board to a component side, whereby a thermal over the at least one metallized bore Contact between the heat dissipation wall (6) and an electrical component of the power electronics (30) is provided.

9. Electrical coolant pump according to one of claims 1 to 5, wherein at least one opening is arranged in a circuit board of the power electronics (30), and a metallic component extends from a rear side through the opening to a component side of the circuit board, whereby over the metallic component a thermal contact is provided between the heat dissipation wall (6) and an electrical component of the power electronics (30).

10. Electric coolant pump according to one of claims 1 to 5, wherein the heat dissipation wall (6) has pronounced sections which are in thermal contact with a rear side of a circuit board of the power electronics (30).

11. Electric coolant pump according to one of claims 1 to 5, wherein the heat dissipation wall (6) has a pronounced portion, and an opening is arranged in a circuit board of the power electronics (30), wherein the pronounced section extends from a rear side of the circuit board through the opening to a component side of the circuit board, whereby a direct thermal contact between the heat dissipation wall (6) and an electrical component of the power electronics (30) is provided.