WO2023131409A1

WO2023131409A1 - Coolant pump for the cooling circuit of a vehicle

Info

Publication number: WO2023131409A1
Application number: PCT/EP2022/050244
Authority: WO
Inventors: Sebastian Cramer; Stefan Rothgang; Stephan NUSSER; Kanqiu Wang; Sven Nigrin
Original assignee: Pierburg Gmbh
Priority date: 2022-01-07
Filing date: 2022-01-07
Publication date: 2023-07-13

Abstract

Coolant pumps are known for cooling circuits of vehicles with an electric motor (30) which has a stator (38) and a rotor (46) which is connected to a drive shaft (26), with a pump head (10), in which a coolant inlet (12), a coolant outlet (16) and a delivery channel (14) are configured, with an impeller (18) which is connected to the drive shaft (26) and is arranged rotatably in the pump head (10), with a can (74) which separates a rotor chamber (72), which is connected fluidically to the delivery channel (14) and in which the rotor (46) and the drive shaft (26) are arranged, from a stator chamber (76), in which the stator (38) is arranged, and with an electronics chamber (56) which is arranged on a side of the electric motor (30) which is axially opposite the pump head (10) and in which an electronics unit (62) is arranged which has a power electronics system (68). In order to improve the cooling of the power electronics system, it is proposed according to the invention that the rotor chamber (72) is connected fluidically to an electronics cooling chamber (94) which is separated from the electronics chamber (56) axially by a wall (70), wherein a coolant channel (96) extends from a side of the electronics cooling chamber (94) which lies directly axially opposite the power electronics system (94), at the end of which coolant channel (96), which faces the electronics chamber (56), a lower pressure prevails than at the opposite end.

Description

DESCRIPTION

Coolant pump for the cooling circuit of a vehicle

The invention relates to a coolant pump for the cooling circuit of a vehicle with an electric motor which has a stator and a rotor which is connected to a drive shaft, a pump head in which a coolant inlet, a coolant outlet and a delivery channel are formed, an impeller which is connected to the is connected to the drive shaft and is arranged rotatably in the pump head, a can, which separates a rotor chamber, which is fluidically connected to the delivery channel and in which the rotor and the drive shaft are arranged, from a stator chamber in which the stator is arranged, an electronics chamber , which is arranged on a side of the electric motor that is axially opposite to the pump head and in which an electronics unit is arranged, which has power electronics.

Such coolant pumps are used to circulate the coolant in a coolant circuit and can be used both in vehicles with internal combustion engines and in battery-powered vehicles or hybrid vehicles or fuel cell vehicles in order to ensure adequate cooling of the heat-producing components.

In most cases, electrically driven canned pumps are used for this, in which a separating tube is arranged between the stator with the windings and the rotor carrying permanent magnets used in electronically commutated electric motors, which on the one hand ensures that no coolant gets to the sensitive windings of the stator, but on the other hand this coolant very much is brought close to the heat-generating windings, so that the heat generated in the windings can be reliably dissipated. Furthermore, the rotor space filled with coolant is often brought close to electronics of the coolant pump for heat dissipation, in order to also dissipate heat there.

Thus, CN 208128083 U discloses a cooling water pump which is driven by a canned motor. The cooling water enters the rotor chamber through openings in the A end shield, flows around the rotor and reaches a cooling water chamber on the opposite side of the rotor to the impeller. This cooling water space is separated from an electronics space by a B end shield, which is also cooled accordingly. The coolant reaches the back of a hollow shaft that carries the impeller, so that the cooling water flows from here back through the hollow shaft to the suction side of the pump. The disadvantage is that dead spaces can form in the cooling water space behind the rotor, which have a low flow rate, as a result of which different amounts of heat are dissipated from different areas of the electronics space. This can lead to overheating of the power electronics, where a particularly large amount of heat is generated.

The object is therefore to provide a coolant pump that ensures that a sufficient amount of heat is reliably dissipated, especially from areas of the electronics in which large amounts of heat are generated, in order to prevent overheating of the power electronics in particular.

This object is achieved by a coolant pump for the cooling circuit of a vehicle having the features of main claim 1.

The coolant pump according to the invention for the cooling circuit of a vehicle has an electric motor which, in particular, can be used electronically commutated DC motor is designed and has a stator with windings and a rotor with permanent magnets, which is connected to a drive shaft, in particular by pressing or gluing on the drive shaft. An impeller is attached to one end of the shaft to generate a pressure drop when the drive shaft rotates with the impeller. This impeller is rotatably arranged in a pump head, into which coolant flows via a mostly axial coolant inlet into the impeller, or flows between the conveyor blades of the impeller and from there is conveyed into a particularly spiral-shaped conveying channel surrounding the impeller, from which it flows to a coolant outlet , which extends in particular tangentially from the delivery channel to the outside of the pump head. Furthermore, the coolant pump has a can that has a rotor chamber that is fluidically connected to the delivery channel, for example via one or more channels that can be formed on the side of the impeller on the A end shield that is opposite to the inlet, and in which the Rotor and the drive shaft are arranged, opposite a stator space in which the stator is arranged separates. Correspondingly, coolant flows into the rotor chamber, as a result of which the windings of the stator are cooled. An electronics compartment of the electric motor is arranged on the side of the pump head opposite the pump head and accommodates an electronics unit which, for example, has a printed circuit board with various electronic components. This electronics unit includes power electronics, in particular an IGBT module, which generates a lot of heat during operation. According to the invention, the rotor chamber is fluidically connected to an electronics cooling chamber, which is axially separated from the electronics chamber by a wall, with a coolant channel extending from a side of the electronics cooling chamber that is directly axially opposite to the power electronics, at the end of which facing the electronics chamber there is a lower pressure than at the opposite end . This means that there is an electronics cooling chamber through which the coolant is routed directly to the wall behind the power electronics, so that first of all, immediate proximity to improve heat dissipation is ensured. In other words, viewed in the circumferential direction of the coolant pump, the coolant channel branches off from the area of the electronics cooling chamber opposite the power electronics. In addition, the coolant duct extending from precisely this area of the electronics cooling chamber opposite the power electronics, in which there is a pressure gradient, ensures that the coolant is discharged from the electronics cooling chamber, since a forced flow through this region of the electronics cooling chamber is produced by the pressure gradient in the duct extending from it. Compared to known designs, this results in improved heat dissipation, in particular from the endangered area of the heat-generating power electronics, since dead spaces in the area adjacent to the power electronics that are not or only poorly traversed are prevented. A thermal overload of the coolant pump can thus be ruled out even with high and long-lasting electrical loads.

The drive shaft is preferably designed as a hollow shaft with an inner channel which is fluidically connected to the electronics cooling chamber via the coolant channel, the inner channel opening out at the coolant inlet of the pump head. The pressure drop in the coolant channel is realized by connecting the coolant channel to the suction side of the pump via the inner channel of the hollow shaft. A circuit of the coolant is created in the pump in which dead spaces are prevented, especially in the area of the power electronics.

In an advantageous embodiment, the coolant duct initially opens into a cooling space which is formed axially between the hollow shaft and the wall delimiting the electronics space, the cooling space being fluidically connected directly and exclusively via the one coolant duct to the electronics cooling chamber. This means that exactly there is a connection between the cooling chamber and thus the hollow shaft to the electronics cooling chamber. Any coolant from the rotor space must be discharged accordingly via the hollow shaft and through the electronics cooling chamber. This creates currents that lead to turbulence in the area of the electronics cooling chamber, which also improves heat dissipation.

A further improvement in heat dissipation is produced in that the power electronics have a delimiting housing surface which rests on the wall separating the electronics space from the electronics cooling chamber. This large contact area results in good heat transfer to the separating wall and thus also to the coolant.

The cooling chamber for the electronics is preferably of ring-shaped design, so that the most complete possible contact is made with the separating wall radially outside the bearing receptacle, and heat can thus be dissipated uniformly from the entire electronics space.

In an advantageous embodiment, the ring-shaped electronics cooling chamber has an expansion in the area axially opposite the power electronics, so that it can be ensured that the entire area opposite the power electronics is also actively cooled.

A particularly simple installation and sealing results when the wall separating the electronics space from the electronics cooling chamber is formed by an end shield of the electric motor that is remote from the pump head. In this case, the bearing plate is understood to mean a housing part which, on the one hand, accommodates the bearing of the electric motor and, on the other hand, forms an axial boundary. The end shield removed from the pump head is often referred to as the B end shield and the end shield placed on the pump head as the A end shield. In a preferred embodiment of the invention, the coolant channel connecting the electronics space to the inner channel of the hollow shaft is formed in the end shield remote from the pump head. This can be implemented, for example, by simply drilling a hole. Additional components to be mounted can thus be omitted.

In a further preferred embodiment, the electronics cooling chamber is delimited by the end shield removed from the pump head and the can. Accordingly, only one seal has to be provided for reliable sealing. This makes assembly easier.

In a further embodiment of this, an annular projection of the split tube lies radially against an annular projection of the bearing plate remote from the pump head, with a sealing ring being interposed. Thus, the assembly and sealing can be done in a simple manner, for example, by pushing the seal onto the projection of the can and then pushing the bearing plate onto the can.

A further reduction in the number of individual parts and the consequent simplification of assembly is achieved in that an end shield of the electric motor that delimits the pump head is designed in one piece with a housing that radially delimits the electric motor and the electronics space. The stator, the front bearing, the can and the rotor with the shaft can be pushed into this housing. The pump head and the B end shield can also be mounted directly on this part of the housing.

The bearing plate delimiting the pump head preferably has an annular projection, against which an axially extending annular section is reduced with the interposition of a second sealing ring diameter of the split tube. This means that the can can also be sealed and assembled to the end shield on this side by simply pushing it in.

Furthermore, at least one connecting channel is advantageously formed in the end shield delimiting the pump head, via which connecting channel the delivery channel is connected to the rotor space. This connection can be made with a simple drill hole. Due to the pressure in the delivery channel, the coolant is also pressed to the rear of the impeller and from here into the rotor chamber, in which the pressure is lower than in the delivery channel, so that there is a driving pressure gradient, through which the flow through the rotor chamber and thus the Cooling of the stator and subsequently the electronics unit is ensured.

A coolant pump for the cooling circuit of a vehicle is thus made available, which is simple and inexpensive to manufacture and assemble and at the same time reliably cools the heat-generating components. In particular, it is ensured that there is sufficient heat dissipation from the power electronics area.

An embodiment of a coolant pump according to the invention is shown in the figure and is described below.

The figure shows a side view of a coolant pump according to the invention in a sectional representation.

The coolant pump according to the invention has a pump head 10 designed as a spiral housing, which has an axially extending, central coolant inlet 12 and a coolant outlet 16 extending tangentially from a spiral-shaped delivery channel 14. A rotatable impeller 18 is arranged in the pump head 10, via which the Coolant is conveyed from the coolant inlet 12 via the conveying channel 14 to the coolant outlet 16 . On the side of the impeller 18 facing away from the coolant inlet 12 , the pump head 10 and the delivery channel 14 are delimited by a first bearing plate 20 .

This first bearing plate 20 has a central bearing seat 22 in which a first bearing 24 is arranged, which supports a drive shaft 26 designed as a hollow shaft, on the end of which the impeller 18 is fastened. The first bearing plate 20 is formed in one piece with an outer housing 28 which extends axially from the radially outer region of the bearing plate 20 in the opposite direction to the pump head 10 and completely surrounds an electric motor 30 . The pump head 10 has a radially outer, annular section 32 extending axially to the housing 28, which is pushed over the end shield 20 or the housing 28 with the interposition of a sealing ring 34, which is arranged in a radial groove 36 of the housing 28, and there is attached.

The electric motor 30 consists of a stator 38 which has a laminated core 40 on the teeth of which support elements 42 are pushed which support windings 44 of the stator 38 . The stator 38 is fixed to the inner wall of the housing 28 . A rotor 46 is formed in the radial interior of the stator 38, which carries permanent magnets 48 and which is fastened to the drive shaft 26, so that the rotor 46 is rotated with the drive shaft 26 when the windings 44 of the stator 38 are energized accordingly, causing a rotation of the Impeller 18 and a promotion of the coolant is generated. The drive shaft 26 is mounted on its side facing away from the pump head 10 in a second bearing 50 which is fastened in a bearing seat 52 of a second bearing plate 54 .

The second bearing plate 54 limits the electric motor 30 to the

Pump head 10 opposite side axially and is located radially on the inside Inner wall of the housing 28, which extends beyond the second bearing plate 54 and also radially surrounds an electronics space 56, which is closed axially by a cover 58 with the interposition of a further sealing ring 60.

An electronics unit 62 is arranged in the interior of this electronics space 56 , which consists of a printed circuit board 64 and electronic components 66 arranged thereon for controlling the electric motor 30 . The electronic modules 66 have, among other things, power electronics 68, that is to say power transistors, which are combined in an IGBT module, for example.

In order to cool this electronics unit 62 , the coolant is guided up to a wall 70 which separates the electronics space 56 from a rotor space 72 formed beyond the wall 70 . In the present exemplary embodiment, this wall 70 is formed by the second end shield 54 . The rotor space 72 is the area of the electric motor 30 in which the rotor 46 and the drive shaft 26 are arranged. This rotor chamber 72 is separated by a can 74 from a radially outer stator chamber 76 in which the stator 38 is arranged in order to prevent the coolant from reaching the windings 44 which are sensitive to corrosion.

In order to separate the rotor chamber 72 from the stator chamber 76, the second end shield 54 has an annular projection 78 which extends axially in the direction of the stator 38 and on whose radially inner side a sealing ring 80 is arranged, which in turn has its inner side against an annular to the second bearing plate 54 pointing annular projection 82 of the can 74 rests. The projection 78 of the second end shield 54 rests axially against a wall surface of the can 74 that extends radially along the end of the stator 38 . On the side facing the pump head 10, the split tube 74 has an axially extending, annular section 84 of reduced diameter, which surrounds the first bearing seat 22 of the first bearing plate 20 and on the radial outside of which another sealing ring 86 is arranged, the outside of which faces against a projection 88 of the first bearing plate 20 which extends axially to the rotor space 72 . Correspondingly, the rotor chamber 72 is delimited by the two end shields 20, 54 and the can 74.

In the first bearing plate 20, which is arranged closer to the pump head 10, axial connecting channels 90 are formed radially adjacent to the bearing mount 22, via which a space 92 between the impeller 18 and the bearing plate 20 and thus the delivery channel 14 is fluidly connected to the rotor space 72, so that coolant can flow into the rotor space 72 . There the coolant flows around the rotor 46 and reaches the area between the rotor 46 and the second end shield 54.

In order to bring the coolant as close as possible to the electronics unit 62, there is an annular electronics cooling chamber 94 in the second end shield 54, which is separated from the electronics space 56 only by the wall 70, which is made as thin as possible in this area. This essentially ring-shaped electronics cooling chamber 94 extends radially inward from the ring-shaped projection 78 of the second end shield 54 .

According to the invention, viewed in the circumferential direction, a coolant duct 96 branches off radially inwards from an area of the electronics cooling chamber 94, which is arranged directly opposite the power electronics 68 in relation to the wall 70 of the second bearing plate 54, and opens into a cooling space 98, which is located axially between the drive shaft 26 and the end shield 54 is formed. This cooling chamber 98 thus borders directly on an inner channel 100 of the drive shaft 26 designed as a hollow shaft, which opens out at the coolant inlet 12 of the pump head 10, so that in Coolant channel there is a driving pressure drop in the direction of the cooling chamber.

In addition, the ring-shaped electronics cooling chamber 94 has a radial expansion 102 in the area opposite the power electronics 68 in order to increase the directly effective cooling surface. Furthermore, the cooling effect is increased by a delimiting housing surface 104 of the power electronics 68 lying against the wall 70 of the second end shield 54, so that a good heat transfer from the power electronics 68 to the wall 70 is produced and this heat is dissipated via the contacting coolant can.

By choosing the position of the branching off of the coolant channel 96 from the electronics cooling chamber 94, due to the existing pressure drop, coolant is always conveyed from the area where the most heat is generated, namely the area directly opposite the power electronics 68. In this way, a turbulent flow is achieved in this area, which means that large amounts of heat can be dissipated and overheating of the power electronics is reliably prevented.

It should be clear that the scope of protection is not limited to the described embodiment. The pump can also be manufactured with a solid shaft and the cooling chamber can be dispensed with. The coolant could also be discharged to other positions via the coolant duct, as long as the branching occurs from the space immediately behind the power electronics and there is a driving pressure drop in the coolant duct.

Claims

Pierburg GmbH, 41460 Neuss PATENT CLAIMS

1. Coolant pump for the cooling circuit of a vehicle with an electric motor (30) which has a stator (38) and a rotor (46) which is connected to a drive shaft (26), a pump head (10) in which a coolant inlet ( 12), a coolant outlet (16) and a conveying channel (14), an impeller (18) which is connected to the drive shaft (26) and is rotatably arranged in the pump head (10), a can (74) which has a Rotor chamber (72), which is fluidically connected to the conveying channel (14) and in which the rotor (46) and the drive shaft (26) are arranged, separates from a stator chamber (76) in which the stator (38) is arranged , and an electronics compartment (56) which is arranged on a side of the electric motor (30) which is axially opposite to the pump head (10) and in which an electronics unit (62) is arranged which has power electronics (68), characterized in that the Rotor space (72) is fluidically connected to an electronics cooling chamber (94), which is axially separated from the electronics space (56) by a wall (70), with a coolant channel extending from a side of the electronics cooling chamber (94) directly axially opposite to the power electronics (68). (96) extends, at the end facing the electronics compartment (56) there is a lower pressure than at the opposite end.

2. Coolant pump for the cooling circuit of a vehicle according to claim 1, characterized in that the drive shaft (26) is designed as a hollow shaft with an inner channel (100) which is fluidically connected to the electronics cooling chamber (94) via the coolant channel (96), the inner channel (100) opening at the coolant inlet (12) of the pump head (10). . Coolant pump for the cooling circuit of a vehicle according to Claim 1 or 2, characterized in that the coolant channel (96) opens into a cooling space (98) which is formed axially between the drive shaft (26) and the wall (70) delimiting the electronics space (56). is, wherein the cooling chamber (98) is fluidly connected directly and exclusively via the one coolant channel (96) with the electronics cooling chamber (94). Coolant pump for the cooling circuit of a vehicle according to one of the preceding claims, characterized in that the power electronics (68) has a delimiting housing surface (104) which rests on the wall (70) separating the electronics compartment (56) from the electronics cooling chamber (94). Coolant pump for the cooling circuit of a vehicle according to one of the preceding claims, characterized in that the electronics cooling chamber (94) is annular. Coolant pump for the cooling circuit of a vehicle according to Claim 5, characterized in that the ring-shaped electronics cooling chamber (94) has an enlargement (102) in the region axially opposite the power electronics (68). 14 Coolant pump for the cooling circuit of a vehicle according to one of the preceding claims, characterized in that the wall (70) separating the electronics compartment (56) from the electronics cooling chamber (94) is protected by an end plate (54) of the electric motor (30) which is remote from the pump head (10). ) is formed. Coolant pump for the cooling circuit of a vehicle according to Claim 7, characterized in that the coolant duct (96) connecting the electronics compartment (56) to the inner duct (100) of the drive shaft (26) is formed in the end shield (54) remote from the pump head (10). Coolant pump for the cooling circuit of a vehicle according to Claim 7 or 8, characterized in that the electronics cooling chamber (94) is delimited by the bearing plate (54) removed from the pump head (10) and the can (74). Coolant pump for the cooling circuit of a vehicle according to one of claims 7 to 9, characterized in that an annular projection (82) of the can (74) radially with the interposition of a sealing ring (80) against an annular projection (78) of the pump head (10) removed end shield (54). Coolant pump for the cooling circuit of a vehicle according to one of the preceding claims, characterized in that 15 an end shield (20) of the electric motor (30) delimiting the pump head (10) is formed in one piece with a housing (28) delimiting the electric motor (30) and the electronics space (56) radially. Coolant pump for the cooling circuit of a vehicle according to Claim 11, characterized in that the bearing plate (20) delimiting the pump head (10) has an annular projection (88) against which, with the interposition of a sealing ring (86), an axially extending annular section (84 ) reduced diameter of the split tube (74). Coolant pump for the cooling circuit of a vehicle according to one of the preceding claims, characterized in that at least one connecting channel (90) is formed in the bearing plate (20) delimiting the pump head (10), via which the delivery channel (14) communicates fluidly with the rotor space (72). connected is.