CN116583676A

CN116583676A - Pump package

Info

Publication number: CN116583676A
Application number: CN202180067430.3A
Authority: CN
Inventors: 阿方索·苏拉切; 达尼洛·穆肖; 卢卡·达莱拉
Original assignee: Industrie Saleri Italo SpA
Current assignee: Industrie Saleri Italo SpA
Priority date: 2020-10-26
Filing date: 2021-09-27
Publication date: 2023-08-11
Also published as: IT202000025315A1; MX2023003495A; EP4232716A1; WO2022090829A1

Abstract

The application is a pump unit (1) that is fluidly connectable to a cooling system of an operating group of a vehicle, such as an internal combustion engine, an electric motor or a battery. The pump unit (1) comprises an impeller (2) and a shaft (3) on which the impeller (2) is integrally mounted. The pump group (1) has at least one electric drive, which in fact comprises an electric motor (4) comprising: a rotor (41) integrally mounted on the shaft (3); and a stator (42). Furthermore, the pump unit (1) comprises a pump body (6) comprising: -a first housing (61) accommodating the impeller (2) in an impeller chamber (610); -a second housing (62) in which the electric motor (4) is housed in the motor chamber (620), wherein the second housing (62) comprises an intermediate tubular wall (625) positioned between the rotor (41) and the stator (42) such that a rotor chamber (621) and a stator chamber (622) are defined in the motor chamber (620) and are hermetically separated from each other; specifically, the first housing (61) and the second housing (62) are separated by a first separation wall (624) comprising an impeller surface (628) facing the impeller chamber (610) and a motor surface (629) facing the motor chamber (620). Even more specifically, the pump stack (1) comprises a thermally conductive resin at least partially covering the motor surface (629) to cool the stator chamber (622) by thermal conduction.

Description

Pump package

The present application relates to a pump stack for a vehicle cooling system.

In the course of the description, the term "vehicle" refers to any mobile tool and hybrid vehicle including an internal combustion engine, without any limitation as to the type or size, i.e. a motor vehicle or an articulated vehicle.

In other words, the present application relates to the automotive industry and in particular to a thermal management system for a vehicle.

In particular, the cooling system is dedicated to cooling an "operating group" of the vehicle.

Specifically, in the present specification, the "operation group" refers to a component or a group of components dedicated to performing a specific operation necessary for the movement of the vehicle. In a preferred embodiment, the "operating group" includes, for example, an engine group of the heat absorbing type or of the electric type.

In other embodiments, the "operating group" includes other components of the vehicle, namely both mechanical-type components (e.g., transmission assemblies) and electrical-type components (e.g., a "battery assembly" included in the vehicle).

In the prior art, several embodiments are known for operating pump groups of a cooling system of a group that differ from each other in terms of the size and type of the actuator.

In particular, the pump set of the present application is one of them, having an electric type drive. In other words, the pump stack of the present application comprises at least one motor controlling the rotational movement of the impeller comprised therein, thereby controlling the movement of the cooling liquid flowing in the cooling system fluidly connectable to the pump stack.

Various technical solutions are known for pump sets comprising electric drives, wherein pump sets of this type have the major problem of being unavoidable, namely the need to effectively cool the motor of the pump set and its related components.

In particular, various embodiments of pump stacks are known in which the cooling liquid present in the chamber housing the impeller is also used to cool the motor and its related components. Even more specifically, in the prior art, there is known a concern about cooling a rotor included therein with a cooling liquid.

Furthermore, several embodiments of pump stacks are known, in which the problems associated with the cooling of the stator are also solved.

In some embodiments, the pump stack has been designed to facilitate cooling of the stator, causing its heat to be dissipated towards the external environment.

However, in other embodiments, a certain amount of oil is provided in the stator chamber in order to cool the stator chamber containing the oil by convection. Examples showing such pump set solutions are shown for example in the inventor's document WO 2020/07562.

On the other hand, these embodiments effectively cool the rotor and/or stator, but fail to effectively cool the rest of the pump stack.

It is therefore an object of the present application to provide a pump group for a cooling system of a vehicle operating group, which effectively cools the entire electronic control unit, thereby eliminating the problems described above.

This object is achieved by a pump set according to claim 1. The dependent claims relate to preferred embodiment variants with other advantageous aspects.

The objects of the application are described in detail hereinafter with the aid of the accompanying drawings, in which:

fig. 1 shows a longitudinal section of a pump stack according to the application according to a first possible embodiment, wherein a thermally conductive resin film on the surface of the motor is shown;

fig. 2 shows a longitudinal section of a pump stack according to the application according to a second possible embodiment, wherein a thermally conductive resin film on the motor surface and a resin film/resin layer on the stator tubular surface are shown;

fig. 3 shows a longitudinal section of a pump stack according to the application according to a third possible embodiment, wherein the heat conducting resin film on the motor surface, the resin film/resin layer on the stator tubular surface and the resin film on the second separating wall are shown;

fig. 4 shows a longitudinal section of a pump set according to the application according to a fourth possible embodiment, wherein a quantity of thermally conductive resin fills the stator chamber and the command chamber;

fig. 5 shows a longitudinal section of a pump stack according to the application according to a fifth possible embodiment, wherein a layer of heat conducting resin on the surface of the motor is shown;

fig. 6 shows a longitudinal section of a pump set according to the application according to a sixth possible embodiment, in which a quantity of thermally conductive resin and a conventional oil fill stator and command chambers;

fig. 7 shows an enlarged view of a part of the pump set shown in fig. 1.

In the above list, the reference numeral 1 generally designates a pump group for a cooling system of a vehicle operating group, preferably a pump group for cooling an engine group (for example of the internal combustion type).

The pump group 1 of the present application extends in length mainly with respect to the axis X-X.

The pump group 1 of the present application comprises an impeller 2 rotatable with respect to said axis X-X. In other words, the impeller 2 has a rotation center on the axis X-X.

Preferably, the impeller 2 is a radial type impeller specially shaped to perform a suction action on the cooling liquid, preferably in the axial direction, and a pushing action, preferably in the radial direction. In particular, the "cooling fluid" is a water-based fluid, for example a solution comprising water and glycol, which circulates in a cooling system of the vehicle to which the pump set 1 of the application can be fluidly connected.

Furthermore, according to the application, the pump group 1 comprises a shaft 3 extending in length along an axis X-X. Preferably, said shaft 3 comprises a rotating end 32 on which the impeller 2 is integrally mounted.

According to the application, the pump unit 1 comprises an electric motor 4 adapted to drive the rotation of the shaft 3.

The motor 4 includes a rotor 41 and a stator 42. According to a preferred embodiment, the rotor 41 and the stator 42 are arranged concentrically with respect to the axis X-X.

According to the application, the rotor 41 is integrally mounted (for example keyed) on said shaft 3: the rotation of the shaft 3 and thus the impeller 2 corresponds to an electronically controlled rotation of the rotor 41. The stator 42 axially and circumferentially surrounds the rotor 41. Specifically, the stator 42 includes a plurality of stator coils forming a stator.

According to the application, the pump unit 1 comprises a pump body 6 extending parallel to and mainly around the axis X-X. The pump body 6 is adapted to contain the various operating components of the pump unit 1 and is adapted to be fluidly connectable to a vehicle cooling system.

According to the application, the pump body 6 comprises along an axis X-X:

a first housing 61 which accommodates the impeller 2 in the impeller chamber 610;

a second housing 62 in which the motor 4 is housed in the motor chamber 620; specifically, the motor chamber 620 accommodates the rotor 41 and the stator 42.

According to the application, the second housing 62 comprises an intermediate tubular wall 625 extending parallel to the axis X-X and positioned between the rotor 41 and the stator 42.

The intermediate tubular wall 625 divides the rotor chamber 621 and the stator chamber 622 in the second housing 62. In other words, the motor chamber 620 is divided into a rotor chamber 621 and a stator chamber 622. Preferably, the rotor chamber 621 and the stator chamber 622 are hermetically isolated from each other.

According to a preferred embodiment, the first housing 61, and in particular the impeller chamber 610 comprised therein, may be in fluid connection with a conduit of a cooling system in which a cooling liquid flows.

According to the present application, the first housing 61 and the second housing 62 are separated by a first separation wall 624. The first separation wall 624 axially defines and tightly seals the motor chamber 620.

Specifically, according to the application, the first separation wall 624 comprises an impeller surface 628 axially facing the impeller 2 and comprises a motor surface 629 axially facing the motor 4. In other words, the impeller surface 628 axially defines the impeller chamber 610, while the motor surface 629 axially defines the motor chamber 620.

Preferably, the first separation wall 624 is included in the first housing 61.

In an alternative embodiment, the first separation wall 624 is included in the second housing 62.

In another embodiment, a portion of the first separation wall 624 is included in the first housing 61 and another portion is included in the second housing 62.

Preferably, the first separation wall 624 is traversed by and supports the shaft 3.

According to a preferred embodiment, the first separation wall 624 comprises at least one cooling hole 624' adapted to place the rotor chamber 621 in fluid communication with the impeller chamber 610 so as to allow a cooling liquid to flow also in said impeller chamber 610. In other words, the cooling hole 624' passes through the first separation wall 624.

According to a preferred embodiment, the shaft 3 comprises an axial hole 300 extending mainly along the axis X-X.

Preferably, the cooling fluid flows inside said axial hole 300. Preferably, the axial bore 300 passes along the shaft 3.

According to a preferred embodiment, the pump stack 6 comprises a third housing 63 in which the electronic command board 5 is housed in the command chamber 630.

According to a preferred embodiment variant, the third housing 63 and the second housing 62 delimit an auxiliary cooling chamber 631 fluidly connected to the rotor chamber 621, so that the cooling liquid also reaches said auxiliary cooling chamber 631 in a fluid manner.

Specifically, according to a preferred embodiment, the second separation wall 623 includes a central portion 6231 that faces the command plate 5 in an area proximate to the auxiliary cooling chamber 631.

According to a preferred embodiment, the second housing 62 and the third housing 63 are separated by a second separation wall 623.

In other words, the command chamber 630 and the stator chamber 622 are partitioned by the second partition wall 623. The second separation wall 623 axially defines and tightly seals the motor chamber 620 together with the first separation wall 624.

In the first preferred embodiment, the second separation wall 623 is included in the second housing 62.

In the second preferred embodiment, the second separation wall 623 is included in the third housing 61.

In another embodiment, a portion of the second separation wall 623 is included in the second housing 62 and another portion is included in the third housing 63.

According to a preferred embodiment, said second separation wall 623 comprises at least one fluid channel adapted to fluidly connect the stator chamber 622 and the command chamber 630.

In a preferred embodiment, the second housing 62 includes an annular sidewall 627 that extends parallel to the axis X-X. Furthermore, the side walls 627 radially define a motor chamber 620, preferably a stator chamber 622.

Preferably, the side walls 627 tightly engage the first separation wall 624 and the second separation wall 623.

As previously described, the second housing 62 includes an intermediate tubular wall 625 that extends parallel to the axis X-X and is positioned between the rotor 41 and the stator 42, dividing the motor chamber 620 into a rotor chamber 621 and a stator chamber 622.

According to a preferred embodiment, the intermediate tubular wall 625 comprises a stator tubular surface 626 radially facing the stator 42 and comprises a rotor tubular surface 626' radially facing the rotor 41.

According to a preferred embodiment, the intermediate tubular wall 625 extends along an axis X-X and comprises: a first end 625' adjacent the first housing 61, preferably in close engagement with the first separation wall 624 (preferably the motor surface 629); a second opposite end 625". Preferably, the second end 625 "engages the bottom of the second housing 62. Preferably, the second end 625 "is adjacent to the third housing 62, tightly sealing the second separation wall 623.

Thus, according to a preferred embodiment, the intermediate tubular wall 625, and in particular the first end 625' thereof, divides the motor surface 629 into at least two distinct surfaces. In particular, the intermediate tubular wall 625 divides the first separation wall 624 (and in particular the motor surface 629) into a rotor portion 6291 axially facing the rotor 41 and a stator portion 6292 axially facing the stator 42.

In other words, the motor surface 629 comprises the rotor portion 6291 and the stator portion 6292.

According to the application, the pump stack 1 comprises a thermally conductive resin.

Preferably, for example, the thermally conductive resin is a thermally conductive epoxy resin.

Preferably, for example, the thermally conductive resin is two-component, for example it is made of polydimethylsiloxane.

Specifically, the heat conductive resin has a high heat conductivity, and is therefore suitable for forming a preferential heat vector in the pump body 6. In other words, the placement of the heat conductive resin helps to cool the motor 4 by heat conduction.

According to the application, the thermally conductive resin at least partially covers the motor surface 629 included in the first separation wall 624 for cooling the stator chamber 622 by thermal conduction.

Specifically, in fact, the first separation wall 624 (specifically the impeller surface 628) is wetted by the cooling liquid and cooled. Meanwhile, the first separation wall 624 also includes a stator portion 6292 facing the stator chamber 629. Thus, the heat generated by the stator 62 heats the stator portion 6292.

According to the above, there is a temperature gradient between the impeller surface 628 and the stator portion 6292, and the thermally conductive resin forms a preferential thermal vector affecting the temperature gradient so as to guide the temperature gradient.

In other words, the heat generated by the stator 62 and present in the stator chamber 620 is the object of the heat vector achieved by the heat conductive resin, and the heat is thus transferred from the stator chamber 620 to the impeller chamber 610 via the heat conduction through the first separation wall 624.

According to a preferred embodiment, the thermally conductive resin at least partially covers the stator tubular surface 626 for cooling the stator chamber 620 by thermal conduction.

Specifically, on the intermediate tubular wall 625, there is a temperature gradient between the stator tubular surface 626, heated by the heat present in the stator chamber 622, and the rotor tubular surface 626' cooled by the cooling liquid flowing in the rotor chamber 621. Heat transfer from the stator chamber 622 to the rotor chamber 621 occurs via heat conduction through the intermediate tubular wall 625, and the presence of the thermally conductive resin facilitates such heat exchange.

According to another preferred embodiment, the thermally conductive resin at least partially covers the second separation wall 623 for cooling the command chamber 630 by thermal conduction.

In a preferred embodiment, the electronic command board 5 is accommodated in the command chamber 630 in a region close to the second separating wall 624.

In a preferred embodiment variant, the electronic command board 5 is fixed (e.g. bolted or glued) to the second separation wall 623.

In a preferred embodiment, a thermally conductive resin is placed between the second separation wall 623 and the electronic instruction board 5.

Thereby, the transfer by heat conduction of the heat present in the command chamber 630 through the second separation wall 623 is optimized. In other words, the electronic command board 5 is cooled more effectively due to the presence of the heat conductive resin covering the second separation wall 623.

In a preferred embodiment variant, the electronic command board 5 is fixed (e.g. bolted or glued) to the second separation wall 623, and a thermally conductive resin is also placed around said electronic command board 5.

According to a preferred embodiment, the thermally conductive resin at least partially covers the central portion 6231 facing the command chamber 630 so as to cool the command chamber 630 by convection.

Specifically, there is a temperature gradient between the central portion 6231 heated by the heat generated by the electronic command board 5 and the auxiliary cooling chamber 631 cooled by the coolant at this time.

In other words, the electronic command board 5 is cooled more effectively to a greater extent.

According to a preferred embodiment, in the above embodiment, the heat conductive resin is positioned on the aforementioned wall in the form of a film.

In other words, the thermally conductive resin is positioned on the associated wall with a minimum thickness.

In other embodiments, the thermally conductive resin is positioned in layers on the aforementioned walls and surfaces. Thus, unlike the previous embodiment in the form of a film, it has a greater thickness.

In particular, it is preferable that the thickness of the heat conductive resin is such that the heat conductive resin is in contact with the corresponding wall on which it is located on one side and in contact with a surface (e.g., a surface of the stator) included in the facing component on the other side.

According to a preferred embodiment, such as shown in fig. 2, the thermally conductive resin is positioned to axially contact the motor surface 629 and the upper surface of the stator 41, such as the entire upper surface of the various stator coils.

According to a preferred embodiment, the thermally conductive resin is positioned in radial contact with the stator tubular surface 626 and the inner surface of said stator 41.

Thus, in these preferred embodiments, the presence of the thermally conductive resin allows heat transfer directly therethrough, thereby allowing the respective walls and surfaces to communicate and contact. In other words, the presence of air between the relevant wall and surface is eliminated.

According to a preferred embodiment, air is present in the stator chamber 622 and preferably in the command chamber 630, except for the areas where thermally conductive resin is present.

In a preferred embodiment variant, the stator chamber 622 and preferably the command chamber 630 are filled with oil, so as to cool the stator 62 and preferably the electronic command plate 5, respectively, by convection. In other words, the oil wets the area where the thermally conductive resin is present.

In other words, the stator 62 and preferably the electronic command board 5 are in an oil bath (oil bath).

In addition, the oil contacts the heat conductive resin and transfers heat present in the stator chamber 622 and preferably the command chamber 630 to the heat conductive resin by convection.

In other words, the cooling of the entire electronic component is further improved due to the combined presence of the oil and the thermally conductive resin.

In one embodiment, oil is present in the stator chamber 622 and the command chamber 630 in an amount such that the oil contacts the thermally conductive resin in any orientation of the pump stack within the vehicle.

Preferably, the oil is dielectric, i.e. it does not allow electric current to conduct therein.

Preferably, the third housing 63 comprises a closing cap 635 adapted to tightly seal the command chamber 630 housing the electronic command board 5.

In a third preferred embodiment variant, the stator chamber 622 and preferably the command chamber 630 are completely filled with thermally conductive resin. In other words, the stator 62 and preferably the electronic command board 5 are immersed in the heat conductive resin.

Thereby, the cooling of the entire electronic component is further improved by the presence of the thermally conductive resin which completely covers the stator 62 and preferably the electronic command board 5.

According to a preferred embodiment, it is noted that the second separation wall 623 comprises at least one fluid channel 623' adapted to fluidly connect the stator chamber 622 and the command chamber 630.

Preferably, the fluid channel 623' is adapted to facilitate heat exchange between the stator chamber 622 and the command chamber 630. Preferably, the heat exchange is performed by a thermally conductive resin or by oil.

According to a preferred embodiment, the thermally conductive resin is positioned in a substantially fluid form on the desired wall or inside the desired chamber to then polymerize and then cure.

According to a preferred embodiment, the viscosity of the thermally conductive resin in fluid form is lower than 1700mpa×s (or 1700 cP).

According to a preferred embodiment, the conductivity of the thermally conductive resin is greater than 0.3W/mK, preferably 0.5W/mK.

According to a preferred embodiment, the thermally conductive resin has a polymerization time as fast as possible. Preferably, the thermally conductive resin in fluid form having a temperature between 25 ℃ and 50 ℃ polymerizes during a period of time between 3 hours and 20 minutes.

According to a preferred embodiment, the polymerized thermally conductive resin is substantially rubber, i.e. it is not rigid.

According to this preferred embodiment, a heat conductive resin is used as the vibration damping element, and the heat conductive resin preferably has rubber properties.

Innovatively, the pump set fully achieves the intended aim by overcoming the typical problems of the prior art.

Advantageously, in fact, the pump group comprises a thermally conductive resin covering the surfaces of the pump body close to the heated components (in particular stator, rotor and command electronics), thus facilitating the cooling of said components by thermal conduction and the heat exchange between said high temperature components and the "hydraulic portion" of the pump body.

Advantageously, heat generated by the electronic component is efficiently conducted and transferred through the thermally conductive resin.

Advantageously, the combined presence of oil and thermally conductive resin allows for enhanced cooling of the heated component, thereby helping to cool the component by convection.

Advantageously, the thermally conductive resin is advantageous in suppressing vibration.

Advantageously, in the pump stack of the present application, the "insulating" effect is generally greatly reduced by the presence of space in which air is present. In fact, it is advantageous to eliminate the possibility of air constituting an insulating barrier to the heat generated by the stator and/or the command plate.

Advantageously, the presence of the stator and command chambers, completely filled with thermally conductive resin, allows to enhance the cooling of the heated component, thus facilitating the cooling of said component by thermal conduction.

Advantageously, the thermally conductive resin allows the pump stack to operate at a uniform temperature. Advantageously, the presence of oil in the stator chamber and the command chamber allows a uniform temperature.

Advantageously, the pump set of the present application has a greater power with respect to known pump sets of the same size. Advantageously, the pump set of the present application has a more compact size with respect to known pump sets having the same power.

Advantageously, the pump stack may be positioned in any spatial location in the vehicle interior.

It will be apparent to those skilled in the art that variations may be made to the inventive content described above to meet contingent needs, all of which fall within the scope of protection defined in the following claims.

Claims

1. Pump group (1) for a cooling system of an operating group of a vehicle, such as an engine group, said pump group extending with respect to an axis (X-X) and comprising:

i) -an impeller (2) rotatable about said axis (X-X);

ii) a shaft (3) extending along the axis (X-X) and operatively connected to the impeller (2);

iii) An electric motor (4) comprising: a rotor (41) integrally mounted on the shaft (3); and a stator (42) axially and circumferentially surrounding the rotor (41);

iv) a pump body (6) comprising, along said axis (X-X):

-a first housing (61) in which the impeller (2) is housed in an impeller chamber (610) in which a refrigeration fluid circulates;

-a second housing (62) in which the motor (4) is housed in a motor chamber (620), wherein the second housing (62) comprises an intermediate tubular wall (625) extending parallel to the axis (X-X) and positioned between the rotor (41) and the stator (42) such that a rotor chamber (621) and a stator chamber (622) are defined in the motor chamber (620),

wherein the first housing (61) and the second housing (62) are separated by a first separating wall (624) comprising an impeller surface (628) axially facing the impeller (2) and a motor surface (629) axially facing the motor (4);

wherein the pump stack (1) comprises a thermally conductive resin at least partially covering the motor surface (629) to cool the stator chamber (622) via heat conduction through the motor surface (629).

2. Pump group (1) according to claim 1, wherein the motor surface (629) comprises a rotor portion (6291) axially facing the rotor (41) and comprises a stator portion (6292) axially facing the stator (42), wherein the thermally conductive resin at least partly covers the stator portion (6292) for cooling the stator chamber (622) via heat conduction through the motor portion (6292).

3. Pump group (1) according to any of the previous claims, wherein the intermediate tubular wall (625) comprises a stator tubular surface (626) radially facing the stator (42) and comprises a rotor tubular surface (627) radially facing the rotor (41), wherein the heat conducting resin at least partially covers the stator tubular surface (626).

4. Pump group (1) according to any of the preceding claims, comprising a third housing (63) in which an electronic command board (5) is housed in a command chamber (630), wherein the second housing (62) and the third housing (63) are separated by a second separation wall (623), wherein the thermally conductive resin at least partially covers the second separation wall (623) to cool the command chamber (630) via heat conduction through the second separation wall (623).

5. Pump group (1) according to claim 4, wherein the electronic command plate (5) is housed in the command chamber (630) in a region close to the second separation wall (623).

6. Pump group (1) according to claim 5, wherein the thermally conductive resin is located between the second separation wall (623) and the electronic command board (5).

7. Pump group (1) according to any one of claims 4 to 6, wherein the rotor chamber (621) is fluidly connected to the impeller chamber (61), and wherein the third housing (63) and the second housing (62) define an auxiliary cooling chamber (631) fluidly connected to the rotor chamber (621) such that the cooling liquid also reaches the auxiliary cooling chamber (631) in a fluid manner.

8. Pump group (1) according to claim 7, wherein the second separation wall (623) comprises a central portion (6231) facing the command plate (5) in a region close to the auxiliary cooling chamber (631), wherein the thermally conductive resin at least partly covers the central portion (6231) for cooling the command chamber (630) via heat conduction through the central portion (6231).

9. Pump group (1) according to any of the preceding claims, wherein the thermally conductive resin is also used as a vibration damping element, the thermally conductive resin preferably having rubber properties.

10. Pump group (1) according to any of the previous claims, wherein the stator chamber (622) is filled with an amount of oil to cool the stator (42) by convection.

11. Pump group (1) according to any of the previous claims, wherein the command chamber (630) is filled with an amount of oil to cool the electronic command board (5) by convection.

12. Pump group (1) according to claim 10, wherein the third housing (63) comprises a closing cap (635) tightly sealing the command chamber (630).

13. Pump group (1) according to any of claims 10 to 12, wherein the oil is dielectric.

14. Pump group (1) according to any of the preceding claims, wherein the thermally conductive resin positioned on the aforementioned walls and surfaces is in the form of a film.

15. Pump group (1) according to any one of claims 1 to 13, wherein the thermally conductive resin positioned on the aforesaid walls and surfaces is in the form of a layer and the thickness of the thermally conductive resin is such that it is in contact on one side with the respective wall on which it is located and on the other side with a surface comprised in a facing component, for example the surface of the stator.

16. Pump group (1) according to any one of claims 1 to 9, wherein the stator chamber (622) is filled with a thermally conductive resin.

17. Pump group (1) according to any of claims 1 to 9, wherein the command chamber (630) is filled with a thermally conductive resin.

18. Pump group (1) according to any one of claims 4 to 8, wherein the second separation wall (623) comprises at least one fluid channel (623') adapted to fluidly connect the stator chamber (622) to the command chamber (630).