CN109154301B

CN109154301B - Pump unit with electric and mechanical drive on the impeller

Info

Publication number: CN109154301B
Application number: CN201680084347.6A
Authority: CN
Inventors: 阿方索·苏拉切; 马尔科·佩代尔索利
Original assignee: Industrie Saleri Italo SpA
Current assignee: Industrie Saleri Italo SpA
Priority date: 2016-04-07
Filing date: 2016-12-15
Publication date: 2020-09-04
Anticipated expiration: 2036-12-15
Also published as: WO2017175048A1; EP3440361A1; HUE051487T2; ITUA20162382A1; CN109154301A; PL3440361T3; EP3440361B1

Abstract

Pump group (1) for a cooling system of an engine of a vehicle, comprising: -an impeller (2) rotatable about an axis (X-X); -a mechanical drive (3) and a mechanical shaft (300) rotatable by the mechanical drive (3); -an electric drive (4) and an electric axle (400) rotatable by the electric drive (4), wherein the electric axle (4) comprises an electric motor (40). In the pump group (1), the mechanical shaft (300) and the electric shaft (400) extend along an axis (XX) and are operatively connected to the impeller (2) by means of a first one-way clutch (51) and a second one-way clutch (52), respectively.

Description

Pump unit with electric and mechanical drive on the impeller

Technical Field

The present invention relates to a pump group for a cooling system of a vehicle, preferably for cooling an engine, such as an internal combustion engine.

Background

It is well known that it is appropriate to vary the intensity of the cooling effect during normal use of the engine.

For example, when the engine is operating at full load or under traction conditions or on an uphill slope or at high ambient temperatures, intensive cooling is appropriate.

However, under other conditions of use, it is not appropriate to focus on cooling, for example, when starting the engine or after use.

The prior art discloses cooling pumps that have addressed this need.

Cooling pumps are known in practice for electric vehicles, in which the rotational speed of the impeller, and therefore the amount of coolant moved by it during circulation in the cooling circuit, is regulated by the electric drive.

Unfortunately, while such pumps are extremely versatile in their application and can be used for rotation management because of the presence of specialized electronic controls, their delivered power is typically low, limited by the power provided by the vehicle electrical system.

Furthermore, in the event of a malfunction, these pumps do not have a "fail-safe" function, i.e. the possibility of functioning in an emergency configuration when the electric motor is subject to damage.

Also known are mechanically operated pumps, in which the rotation of the impeller is related to the number of revolutions of the internal combustion engine; in these solutions, the regulation of the quantity of coolant is taken care of by dedicated regulating elements located upstream or downstream of the impeller, which are adapted to vary the cross section of the circuit and thus the flow rate of the cooling liquid.

Unfortunately, this solution, although suitable for providing high power and proved to be fairly reliable, is less versatile and generally oversized in relation to the engine speed and the characteristics of the regulating elements. Also, in the "post-run" configuration (i.e., with the engine off), no cooling is performed.

Finally, also known are dual drive pumps, i.e. comprising both an electric drive and a mechanical drive.

Unfortunately, these pumps are rather complex to manage with two drives and also have a bulky articulated structure.

Disclosure of Invention

The object of the present invention is to provide a pump group for a cooling system of a vehicle, for example for an internal combustion engine, which meets the mentioned requirements, overcoming the mentioned drawbacks. In other words, it is an object to provide a double-acting pump group which simplifies the management of the two drives and has a simple and compact structure.

This object is achieved by a pump unit made according to the invention. The invention relates to a preferred embodiment variant with other advantageous aspects.

According to one aspect of the present invention, there is provided a pump group for a cooling system of an engine of a vehicle, comprising: -an impeller rotatable about an axis; -a mechanical drive and a mechanical shaft rotatable by the mechanical drive; -an electric drive and an electric shaft rotatable by the electric drive, wherein the electric drive comprises an electric motor; wherein the mechanical and electric shafts extend along the axis and comprise a mechanical and an electric shaft impeller end, respectively, the mechanical and electric shaft impeller ends being operatively connected to the impeller by means of a first and a second one-way clutch, respectively; in particular, the impeller comprises a central hub arranged on the axis, on which the first one-way clutch and the second one-way clutch are housed.

Drawings

The object of the invention will be described in detail below with the aid of the attached drawings, in which:

figures 1a and 1b show two perspective views of a pump group according to a possible embodiment according to the present invention;

figure 2 shows a longitudinal section of the pump group referred to in figures 1a and 1b according to a variant of the first embodiment;

figure 2' shows an enlarged cross-sectional view of a detail of the pump group shown in figure 2;

figure 3 shows a longitudinal section of the pump group referred to in figures 1a and 1b according to a second embodiment variant;

figure 3' shows an enlarged cross-sectional view of a detail of the pump group shown in figure 3;

figure 4 shows an enlarged cross-sectional view of a detail of the pump group referred to in figures 1a and 1b, according to another embodiment;

figure 5 shows a perspective view of a pump group according to another embodiment of the invention;

figures 6a and 6b show two longitudinal sections of the pump group in figure 5;

figure 6c shows an enlarged cross-sectional view of a detail of the pump group shown in figures 6a and 6 b;

figure 6d shows an enlarged cross-sectional view of a detail of the pump group in another embodiment variant similar to the embodiment of figures 6a and 6 b.

Detailed Description

With reference to the preceding figures, numeral 1 indicates as a whole a pump group for a cooling system of an engine, preferably an internal combustion engine.

The pump group 1 of the invention comprises an impeller 2 rotatable about an axis X-X, so that the rotation of the impeller 2 corresponds to the movement of a predetermined quantity of coolant in the circuit.

Preferably, the impeller 2 is radial, i.e. so that the incoming liquid flow has an overall substantially axial direction and the outgoing liquid flow has a radial direction.

The pump group 1 provides dual drive, that is to say it can be operated both mechanically and electrically. For this purpose, the pump unit 1 comprises a mechanical drive 3 and an electrical drive 4.

In particular, the pump group 1 comprises a mechanical shaft 300, which can be rotated by a mechanical drive 3 and is operatively connected to the impeller 2.

In a preferred embodiment, the mechanical drive 3 comprises a pulley 33 for a drive belt, which is connected to the drive shaft, for example by using a kinematic chain.

Preferably, the pulley 33 is an electromagnetic pulley. In embodiments having an electromagnetic pulley, it is normally engaged and the release mechanism disengages the pulley from the mechanical shaft 300 only when it is actuated (i.e., the coil therein is electrically energized).

Indeed, preferably, the electromagnetic pulley comprises an outer ring on which the drive belt is mounted, an inner ring and an intermediate release mechanism comprising an intermediate coil. In the present embodiment, the inner ring is operatively connected to a machine shaft 300 which is operatively connected to the impeller 2 by means of a first one-way clutch 51 (described below).

Typically (i.e., when the electromagnetic pulley is not energized), the outer ring rotates integrally with the inner ring. In such a configuration in which the electromagnetic pulley is disabled, if the inner ring has a rotational speed greater than that of the driven ring, the mechanical shaft 300 is mechanically dragged to rotate. Conversely, when the electromagnetic pulley is activated (i.e., when the coil is energized), the release mechanism releases the outer ring from the inner ring, thereby causing the outer ring to not impart any rotation to the inner ring, and therefore to the mechanical shaft 300, when driven in rotation by the belt.

In addition, the pump group 1 comprises an electric shaft 400 rotatable by the electric drive 4 and operatively connected to the impeller 2.

Preferably, the electric drive 4 comprises an electric motor 40 comprising a rotor 41 mounted on an impeller portion 401 of the electric shaft 400 and a stator 42 fixed coaxially to the rotor 41.

According to a preferred embodiment, the rotor 41 is of the wet rotor type.

The pump unit 1 further comprises an electronic control unit 45 to control the electric drive 4 and/or the electromagnetic pulley.

According to a preferred embodiment, the pump group 1 comprises a pump body 10 to support and house the various components contained in the pump group 1, previously described and described below. Preferably, the pump body 10 is adapted to allow fluid connection with a cooling system and is adapted to be flanged or connected to other vehicle components, such as an engine.

The pump body 10 comprises a main housing 12 which houses the impeller 2 in an impeller chamber 120, into which coolant enters through an inlet duct 121 and exits through an outlet duct 122, preferably in an axial direction and exiting in a radial direction.

Preferably, the pump body 10 further comprises a mechanical driver housing 13 for supporting the mechanical driver 3, the mechanical driver housing being adapted to support the mechanical shaft 300, preferably by means of special rotating means 135 (such as bearings). In a preferred embodiment, the mechanical drive housing 13 is separated from the impeller chamber 120 by a dynamic seal 6.

Preferably, the pump body 10 also comprises an electric drive housing 14 for supporting the electric drive 4, which is adapted to support the electric shaft 400 in rotation and house the electric motor 40.

Preferably, the electric drive housing 14 is fluidly connected to the impeller chamber 120. Specifically, electric drive housing 14 includes a rotor chamber 140 extending along the axis of electric shaft 400 containing rotor 41 fluidly connected to impeller chamber 120.

Furthermore, in the preferred embodiment, the pump body 10 comprises a control housing 15 placed on the electric drive housing 14, which contains, sealed with respect to the coolant, an electronic control unit 45. The control housing 15 is placed at the opposite end with respect to the impeller 2.

As described above, both the mechanical shaft 300 and the electric shaft 400 are operatively connected to the impeller 2 to control the rotational speed thereof.

Preferably, the mechanical shaft 300 and the electrical shaft 400 extend along an axis X-X.

In a preferred embodiment, the mechanical shaft 300 and the electrical shaft 400 extend in two opposite directions on either side of the impeller 2.

Preferably, the mechanical drive 3 is placed behind the impeller 2, while the electrical drive 4 is placed in front of the impeller 2; similarly, respective housings included in the pump body 10 are located respectively behind and in front of the impeller housing 12 (as shown by way of non-limiting example in the embodiments of fig. 2, 3 and 4).

In another preferred embodiment, the mechanical shaft 300 and the electrical shaft 400 extend in the same direction as the impeller 2, one concentric with the other (in contrast, in the embodiment of fig. 5 and 6a, 6b, as shown by way of non-limiting example).

Preferably, both the mechanical drive 3 and the electrical drive 4 are placed behind the impeller 2; similarly, the respective housings comprised in the pump body 10 are also respectively located behind the impeller housing 12: the electric drive housing 14 is centered along axis XX, with the rotor chamber 140 fluidly connected to the impeller chamber 120, while the mechanical drive housing 13 extends concentrically with axis XX, separated from the impeller chamber 120 by the dynamic seal 6.

Preferably, the rotor chamber 140 is in fluid connection with the impeller chamber 120, preferably adjacent to each other. In some embodiment variations, the rotor chamber 140 is in fluid communication with the impeller chamber 120 through the electric shaft 400 and/or through a special channel 210, for example made through the impeller or through the housing.

In a further embodiment variant (not shown), both the mechanical drive 3 and the electrical drive 4 are placed in front of the impeller 2; similarly, the respective housing included in the pump body 10 is also located in front of the impeller housing 12, respectively.

The machine shaft 300 and the electric shaft 400 comprise a machine shaft impeller end 302 and an electric shaft impeller end 402 operatively connected to the impeller 2 by means of a first one-way clutch 51 and a second one-way clutch 52, respectively.

In other words, the first one-way clutch 51 is interposed between the mechanical shaft 300 and the impeller 2, while the second one-way clutch 52 is placed between the electric drive and the impeller.

According to a preferred embodiment, the impeller 2 comprises a central hub 20 arranged on the axis X-X, the first one-way clutch 51 and the second one-way clutch 52 being housed on the central hub 20. In addition, the impeller 2 comprises a blade portion 21 having a radial extension from the central hub 20. In one embodiment, the central hub 20 is integral with the blade portion 21; in other embodiments, the central hub 20 and the blade section 21 are two distinct, mutually mounted elements.

Preferably, the first one-way clutch 51 and the second one-way clutch 52 are co-molded with the impeller 2, preferably they are co-molded with the central hub 20.

According to a preferred embodiment, the first one-way clutch 51 comprises a rolling bearing for supporting the machine shaft impeller end 302 in rotation. For example, the type of rolling bearing is a rolling bearing with rollers or needles, having rolling elements placed between the driven ring and the drive ring.

According to a preferred embodiment, the second one-way clutch 52 includes a rolling bearing for supporting the electric axle impeller end 402 in rotation. For example, the type of rolling bearing is a rolling bearing with rollers or needles, having rolling elements placed between the driven ring and the drive ring.

In the preferred embodiment, the first one-way clutch 51 and the second one-way clutch 52 are arranged side by side along the axis X-X.

In another preferred embodiment, the first one-way clutch 51 and the second one-way clutch 52 are arranged concentrically with each other. Preferably, in the present embodiment, the first one-way clutch 51 and the second one-way clutch 52 are axially parallel to the axis X-X, while at least a portion overlaps.

Depending on the type and arrangement of these one-way clutches, the central hub 20 is specially shaped to operatively connect to the impeller end of the machine shaft 300 and/or the motorized shaft 400, thereby supporting and/or housing the clutches and the respective impellers of the motorized and machine shafts. That is, the central hub 20 is specially shaped to receive and/or support the respective clutches such that they face inwardly and/or outwardly. According to a preferred embodiment, the central hub 20 has a compact size, i.e. extends along the axis XX over a length substantially equal to or slightly greater than the height of the blade portion 21 (as shown in figures 2 and 3). In other preferred embodiments, the central hub 20 is also adapted to extend along the axis X-X for a longer portion of the length, which proves to be twice or three times as large as in the previous embodiments. In some preferred embodiments, the central hub 20 comprises a through cavity along axis X-X; in other preferred embodiments, the central hub 20 includes two respective cavities made at the axial ends.

Preferably, in an embodiment similar to that shown in fig. 3, the machine shaft impeller end 302 includes a pin 302' extending along the axis XX, while the electric shaft impeller end 402 includes a housing 402' adapted to receive and rotatably support the pin 302 '.

In contrast, in one embodiment variation (not shown), the electric shaft impeller end 402 includes a pin extending along the axis X-X, while the mechanical shaft impeller end 302 includes a housing adapted to receive and rotationally support the pin.

According to a preferred embodiment, the pins are housed in respective housings comprising bushings adapted to limit the friction between the two shafts.

Another aspect of the pump group 1 according to the preferred embodiment relates to the fact that: motorized shaft 400 has inside it a central duct 450 extending in length along axis X-X; preferably, the central conduit 450 has radial entry ports 450' near both ends thereof. In other words, due to the presence of the central duct 450, the coolant filling the rotor chamber 140 also flows inside the electric shaft 400 through the central duct 450. Preferably, in addition to the coolant present in the impeller chamber 120, the rotating impeller 2 also draws in the coolant through a central conduit 450 present in the rotor chamber 140.

Other preferred embodiments of the pump group 1 exist, including the following: the pump stack 1 comprises a throttle valve (not shown) housed in the pump body so as to be placed along the outlet duct 122 from the impeller chamber 120. This valve may be controlled using an actuator (not shown), e.g. electrically, hydraulically or vacuum, preferably by a control means. The characteristics of such valves are disclosed in documents representative of the applicant, EP2534381, EP13188771, EP13801735, WO2015/059586 and BS2014a 000171.

Furthermore, according to a further embodiment, the pump group 1 comprises, upstream of the impeller 2 in the inlet duct 121, a regulating cylinder (not shown) adapted to regulating the amount of coolant flowing to the impeller. The characteristics of said closed cartridge are described, for example, in document WO2015/004548, representative of the applicant.

According to the above described embodiment, electronic control is implemented for the electric drive 4 and/or possibly the electromagnetic pulley, based on the occurrence of certain conditions during use of the vehicle.

In the normal configuration, the electromagnetic pulley is not energized and the electric drive 4 is switched off, so the impeller 2 is moved only by the electromagnetic pulley, i.e. by the rotation of the mechanical shaft 300.

For example, when starting the vehicle, if the engine is still cold (so-called "warm-up" configuration), the electromagnetic pulley is activated so as to release the action on the mechanical shaft 300 when the electric drive 4 is stopped. Thus, the impeller 2 remains stationary, liquid does not circulate in the circuit, and the motor warms up more quickly.

According to another example, under heavy load conditions, such as when the vehicle is towing a trailer or climbing a hill, typically at low speeds (and therefore low engine speed), the electric drive 4 is activated to rotate the electric shaft 400 at a speed greater than the speed induced by the mechanical drive 3 and the mechanical shaft 300, so that the impeller 2 rotates at the speed induced by the electric shaft 400.

Advantageously, in this configuration, the first one-way clutch 51 disengages the rotating impeller 2 from the mechanical shaft 300, thereby reducing the mass of the electric drive 4 dragging in rotation.

According to another example, after use of the vehicle, if the coolant is still very hot, the electric drive 4 is activated in order to keep the impeller 2 rotating (this phase is called "after run"). In this way, the impeller 2 rotates at a predetermined rotational speed, while the mechanical drive 3 is completely inoperative, since the vehicle engine has been shut off. Specifically, for example, the electromagnetic pulley is not energized, which is not necessary for the movement of the rotation shaft. Also in this case, the first one-way clutch 51 disengages the rotating impeller 2 from the mechanical shaft 300, thereby reducing the mass of the electric drive 4 dragging in rotation.

In general, therefore, the electric drive 4 is activated whenever an increase in the cooling capacity in relation to the engine speed is required (irrespective of the mechanical drive 3).

For example, in one embodiment (the pump group 1 comprises a mechanical drive 3 with a "classic pulley" of the mechanical type, and therefore cannot be controlled electronically, and the above-mentioned throttle valve is in the above-mentioned "warm-up" phase in which the engine is still cold, and needs to be heated up as quickly as possible), the amount of coolant in the cycle is regulated by controlling the positioning of the throttle valve.

The pump group according to the present invention innovatively meets the cooling requirements of the engine and overcomes the above-mentioned drawbacks.

Firstly, advantageously, the flexibility of the pump group according to the invention is very high, since it responds to the cooling needs of the vehicle according to the actual demand, rather than the engine speed or the electrical availability of the system. That is, advantageously, the pump group proves to be particularly suitable for managing the coolant quantity in the cooling system in its entirety (for example, by managing the cooling of other vehicle components (such as a turbomachine) than the engine), avoiding the need to have specific electric pumps to move predetermined quantities of coolant in these components, thus striving for additional space in the engine compartment.

Furthermore, advantageously, the pump group is extremely compact and small in size, making it particularly suitable for being housed in the engine compartment of a motor vehicle.

For example, advantageously, the impeller (and the impeller chamber with the volute) is more compact and not oversized, and always operates under optimal performance conditions, compared to known pump stacks (where the impeller is usually oversized to compensate for the poor flexibility of mechanical pumps and the limited power of electric pumps).

Another advantageous aspect is that the electric and mechanical drives are directly engaged on the impeller (for example without intermediate shaft), which simplifies the structure of the pump group, which is more compact in size than the solutions of the prior art.

A further advantageous aspect consists in the fact that the pump group requires a small number of dynamic seals: in particular, only one dynamic seal is required to separate the impeller housing from the mechanical drive housing. Advantageously, the motor of the pump group of the invention can be provided with a wet rotor, thus eliminating the need for special dynamic seals, but instead requiring it to be hermetically isolated from the cooling fluid.

Advantageously, the design of the mechanical and electrical drives is considerably simplified and can be optimized by the designer; advantageously, the electromagnetic pulley (if provided) does not require special design updates; advantageously, the rotor of the motor is mounted directly on the impeller shaft without the need for special dust cap bearings, thus limiting the axial footprint of the rotor.

Furthermore, advantageously, the transition from the electric drive to the mechanical drive and vice versa is mechanically operated by the one-way clutches. Advantageously, therefore, the electronic mechanism of the pump group is very simple.

Advantageously, the pump group is able to avoid cooling actions even when the engine is in geared condition, for example, in "warm-up" conditions, heating the electric motor is suitable.

In another advantageous aspect, the pump group has a "fail-safe" feature; in fact, in the event of failure of the electric drive, the pump group continues to ensure the movement of the impeller thanks to the presence of the mechanical drive and of the second one-way clutch.

According to another advantageous aspect, the pump group is in operation in the "after-running" condition (i.e. engine off). Advantageously, in "post-run" conditions, power supply to the electromagnetic pulley can be avoided, thereby saving power.

Another advantageous aspect is that the pump unit has a more limited power absorption compared to standard mechanical pumps.

Advantageously, the impeller may be manufactured to already include a one-way clutch (in practice, the one-way clutch is inserted therein during its moulding operation).

Furthermore, the kinematic chain between the mechanical drive, the electric drive and the impeller is considerably simplified.

Furthermore, advantageously, the second one-way clutch allows the rotor not to rotate through the shaft in the configuration in which the impeller is rotated by the mechanical drive; therefore, no magnetic friction is generated (the rotor-stator set does not operate as a generator either).

Furthermore, advantageously, the first one-way clutch and the second one-way clutch can be selected with different characteristics according to the different actions required by the electric drive and the mechanical drive.

Advantageously, the electric drive is completely free of dynamic seals and bearings supporting the drive shaft, thus providing higher electrical efficiency and a wider range of electrical operation.

Another advantageous aspect also consists in the versatility of the design of the pump group, in particular the versatility of the design of the respective housings, which can be designed as required in order to house and/or support the electric and mechanical drives so as to operatively connect the respective shafts to the impeller.

A further advantageous aspect is that the water chamber in which the rotor of the electric motor is housed is effectively filled with coolant, since the electric shaft on which it is mounted allows an effective recirculation of the coolant, which is in turn sucked in through the central duct.

It is clear that a person skilled in the art can modify the pump group described above to meet contingent requirements, all of which are included within the scope of protection defined by the following claims.

In addition, each variant described as belonging to a possible embodiment can be implemented independently of the other embodiments described.

Claims

1. Pump group (1) for a cooling system of an engine of a vehicle, comprising:

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

-a mechanical drive (3) and a mechanical shaft (300) rotatable by the mechanical drive (3);

-an electric drive (4) and an electric axle (400) rotatable by the electric drive (4), wherein the electric drive (4) comprises an electric motor (40);

wherein the mechanical shaft (300) and the electric shaft (400) extend along the axis (X-X) and comprise a mechanical shaft impeller end (302) and an electric shaft impeller end (402), respectively, which are operatively connected to the impeller (2) by means of a first one-way clutch (51) and a second one-way clutch (52), respectively;

characterized in that said impeller (2) comprises a central hub (20) arranged on said axis (X-X) on which said first one-way clutch (51) and said second one-way clutch (52) are housed.

2. Pump group (1) according to claim 1, wherein the first one-way clutch (51) and the second one-way clutch (52) are co-moulded with the impeller (2).

3. Pump group according to claim 1 or 2, wherein the first one-way clutch (51) comprises a rolling bearing for supporting in rotation the machine shaft impeller end (302).

4. Pump group according to claim 1 or 2, wherein the second one-way clutch (52) comprises a rolling bearing for supporting in rotation the motorized shaft impeller end (402).

5. Pump group according to claim 1 or 2, wherein the first one-way clutch (51) and the second one-way clutch (52) are arranged side by side along the axis (X-X).

6. Pump group according to claim 1 or 2, wherein the first one-way clutch (51) and the second one-way clutch (52) are arranged concentrically to each other.

7. Pump group according to claim 1 or 2, wherein the electrical shaft (400) and the mechanical shaft (300) extend to opposite sides of the impeller (2).

8. Pump group according to claim 7, wherein the mechanical shaft impeller end (302) comprises a pin (302') extending along the axis (X-X), while the electric shaft impeller end (402) comprises a housing (402') suitable to receive and support in rotation the pin (302 ').

9. Pump group according to claim 7, wherein the motorized shaft impeller end (402) comprises a pin extending along the axis (X-X) and the mechanical shaft impeller end (302) comprises a housing suitable to receive and support in rotation the pin.

10. Pump group (1) according to claim 1 or 2, wherein the mechanical drive (3) is located behind the impeller (2) and the electrical drive (4) is placed in front of the impeller (2).

11. Pump group according to claim 1 or 2, wherein the electric shaft (400) and the mechanical shaft (300) extend on the same side of the impeller (2).

12. Pump group (1) according to claim 1 or 2, wherein the mechanical drive (3) comprises an electromagnetic pulley mounted to a pulley end (303) of the mechanical shaft (300), wherein the electromagnetic pulley is normally in engagement, electrically energizable to disengage the mechanical shaft.

13. Pump group (1) according to claim 1 or 2, wherein the electric drive (4) comprises a rotor (41) mounted on a rotor portion (401) of the electric shaft (400) and comprises a fixed stator (42) coaxial to the rotor (41).

14. Pump group (1) according to claim 12, further comprising a pump body (10) comprising:

-a main housing (12) accommodating the impeller (2) in an impeller chamber (120) into which a coolant enters through an inlet duct (121) and exits through an outlet duct (122);

-a mechanical driver housing (13) for supporting the mechanical driver (3) adapted to support the mechanical shaft (300) in rotation, wherein the mechanical driver housing (13) is separated from the impeller chamber (120) by a dynamic seal (6);

-an electric drive housing (14) for supporting the electric drive (4) adapted to support the electric shaft (400) in rotation, wherein the electric drive housing (14) is fluidly connected with the impeller chamber (120).

15. Pump group (1) according to claim 14, wherein the electric drive (4) also comprises an electronic control unit (45) for controlling the electric drive (4) and/or the electromagnetic pulley, wherein the electronic control unit (45) is housed in a control housing (15) provided on the electric drive housing (14) at the end opposite to the impeller end (402) of the electric shaft (400).

16. Pump group (1) according to claim 1 or 2, wherein the motorized shaft (400) has, inside it, a central duct (450) which extends in length along the axis (X-X) and allows the flow of coolant.

17. Pump group (1) according to claim 2, wherein the first one-way clutch (51) and the second one-way clutch (52) are co-moulded with the central hub (20).

18. Pump group according to claim 11, wherein the electric shaft (400) and the mechanical shaft (300) extend in front of the impeller, the electric shaft (400) being concentric with the mechanical shaft (300).

19. Pump group according to claim 13, wherein the rotor (41) is of the wet rotor type.

20. Pump group (1) according to claim 16, the central duct having, near its two ends, radial access ports (450').