A traction system comprising an electric motor and an external liquid-gas heat exchanger for cooling the rotor

Abstract

A traction system for a rail vehicle, comprising: an electric motor comprising a housing comprising a peripheral portion in thermal contact with a stator, the electric motor defining two chambers, the rotor defining a plurality of air passages between the two chambers, the peripheral portion defining a first liquid circuit receiving a first flow of cooling liquid intended to be heated by the stator; a heat exchanger external to the housing, having an air inlet in fluid communication with one of the two chambers, an air outlet in fluid communication with the other chamber and a second liquid circuit receiving a second flow of cooling liquid, the air passages, the two chambers and the heat exchanger defining an air circuit for cooling the rotor, the heat exchanger exchanging heat between the air circuit and the second flow of cooling liquid; a fan for circulating air in the air circuit.

Description

Technical Field

[0001] The present invention relates to a traction system for a rail vehicle, comprising an electric motor including a stator, a rotor adapted to rotate relative to the stator about an axis, and a housing surrounding the stator, the housing, the rotor, and the stator defining two axially opposed chambers.

[0002] The present invention also relates to a rail vehicle including the traction system, and a traction method using the traction system or the rail vehicle. Background Technology

[0003] In this traction system, the electric motor generates heat during operation. Since the motor is enclosed in a housing, the heat needs to be recovered and released to the outside of the housing.

[0004] One known solution is to use a coolant that circulates in the outer portion of the housing, making thermal contact with the stator. Heat from the stator is transferred to the coolant through the outer portion and then dissipated.

[0005] To cool the rotor, an internal air circulation can be created using a fan fixed to the rotor or motor shaft and located within one of the two chambers. Air flows from one chamber to the other through a plurality of first axial channels defined between the stator and the outer portion of the housing, and returns to the one chamber through a plurality of second axial channels defined by the rotor.

[0006] Air absorbs heat from the rotor in multiple second axial channels, and as air circulates in multiple first axial channels, heat is transferred to the coolant through the peripheral portion.

[0007] The solution is satisfactory because the stator and rotor are cooled while enclosed in the housing, but it also has limitations.

[0008] Therefore, one object of the present invention is to provide a traction system that improves cooling efficiency, particularly stator cooling efficiency, without reducing rotor cooling effect. Summary of the Invention

[0009] Therefore, the present invention proposes a traction system for rail vehicles, comprising: - An electric motor including a stator, a rotor adapted to rotate relative to the stator about an axis, and a housing, the housing including a peripheral portion surrounding the stator about the axis, the peripheral portion being in thermal contact with the stator to receive heat from the stator, the housing, rotor, and stator defining two axially opposed chambers, the rotor defining a plurality of air passages between the two chambers, and the peripheral portion defining a first liquid circuit configured to receive a first coolant flow intended to be heated by the heat received from the stator; A heat exchanger, located outside the housing, has an air inlet in fluid communication with one of two chambers, an air outlet in fluid communication with the other of the two chambers, and a second liquid circuit configured to receive a second coolant flow. The air passage, the two chambers, and the heat exchanger define an air circuit suitable for cooling the rotor. The heat exchanger is adapted to exchange heat between the air in the air circuit and the second coolant flow. - A fan is used to circulate air in an air circuit.

[0010] In other embodiments, the traction system may include one or more of the following features, which may be used individually or in any technically feasible combination: - The stator and the peripheral parts are connected to each other in such a way that there is no air passage between the stator and the peripheral parts that allows air in the air circuit to bypass the heat exchanger; - The heat exchanger includes a housing defining an internal volume and a plurality of tubes extending in the internal volume along the direction of liquid circulation and adapted to receive a second flow of coolant, the housing and tubes defining a portion of an air circuit between an air inlet and an air outlet; -The outer shell has a tubular shape; -The direction of liquid circulation is basically parallel to the axis; - The housing forms external heat sinks designed to extend parallel to the longitudinal direction of the vehicle's intended travel; - The axis is basically perpendicular to the longitudinal direction; - The heat exchanger includes a plurality of inner walls extending in an internal volume, the inner walls being arranged sequentially along the direction of liquid circulation, and each inner wall being penetrated by a portion of a tube, each inner wall partially closing off a portion of an air circuit in the direction of liquid circulation to define a zigzag air path in the portion; - The air inlet and air outlet are located at two opposite ends of the heat exchanger in one direction; - The air inlet and air outlet are aligned with the two chambers along two radial directions relative to the axis, the two radial directions being coplanar, and the air inlet and air outlet are located on the same side of the axis along the two radial directions; - The traction system includes a coolant source adapted to provide a first coolant flow and a second coolant flow; - The first liquid circuit and the second liquid circuit are connected in parallel to the coolant source to receive the first coolant flow and the second coolant flow, respectively; and - The first liquid circuit and the second liquid circuit are connected in series with each other and connected to a coolant source. The first coolant flow is intended to flow out of the first liquid circuit to form the second coolant flow, or the second coolant flow is intended to flow out of the second liquid circuit to form the first coolant flow.

[0011] The present invention also proposes a rail vehicle including the above-described traction system.

[0012] This invention proposes a traction method, which includes the following steps: - Obtain the aforementioned traction system or the aforementioned rail vehicle; - The rotor rotates about its axis relative to the stator, and the outer part receives heat from the stator; - A first liquid circuit receives a first coolant flow, which is heated by the heat received from the stator; - The second liquid circuit receives the second coolant flow; - The rotor is cooled via an air circuit, and a heat exchanger facilitates heat exchange between the air in the air circuit and the second coolant flow; and - Use a fan to circulate air in the air circuit. Attached Figure Description

[0013] The invention and its advantages will be better understood by reading the following description, which is given by way of example only and with reference to the accompanying drawings: Figure 1 This is a schematic view of a rail vehicle according to the invention and another rail vehicle according to a variant thereof; Figure 2 yes Figure 1 A schematic partial view of the electric motor and heat exchanger of the traction system of the rail vehicle shown, in cross section along a radial half-plane; Figure 3 yes Figure 1 and Figure 2 A view of the heat exchanger shown, a cross-section along a plane parallel to the motor axis; Figure 4 It is based on Figure 3 A view of a variant of the heat exchanger shown; and Figure 5 yes Figures 1 to 3 The view shown is a cross-section of the heat exchanger along a plane perpendicular to the motor axis. Detailed Implementation

[0014] refer to Figure 1 The following describes the rail vehicle 10 according to the present invention.

[0015] The vehicle 10 includes a traction system 12 and is adapted to travel in the longitudinal direction L.

[0016] The traction system 12 includes an electric motor 14, which includes a stator 16, a rotor 18 adapted to rotate relative to the stator about an axis X, and a housing 20. The traction system 12 includes a heat exchanger 22 located outside the housing and a fan 24, for example, fixed to the shaft 26 of the electric motor and located within an internal volume 28 defined by the housing.

[0017] The traction system 12 advantageously includes a coolant source 30 adapted to provide a first coolant flow 32 and a second coolant flow 34.

[0018] The axis X is, for example, substantially perpendicular to the longitudinal direction L. In this document, when used to describe orientation, "substantially" means, for example, a strict orientation within ±5°.

[0019] The housing 20, rotor 18 and stator 16 define two axially opposed chambers 36 and 38.

[0020] The housing 20 includes a peripheral portion 40 surrounding the stator 16 about an axis X, and advantageously includes two bearing plates 42, 44, extending perpendicular to the shaft 26 on both sides of the outer portion, for example, along the axis X.

[0021] The stator 16 includes, for example, one or more windings 45 radially facing the rotor 18.

[0022] The peripheral portion 40 has, for example, a cylindrical shape centered on the axis X. The peripheral portion 40 is in thermal contact with the stator 16 to receive heat from the stator.

[0023] Thermal contact between the peripheral portion 40 and the stator 16 is ensured by the contact surface 46 of the stator 16, which is advantageously continuous around the axis X. Preferably, the stator 16 and the peripheral portion 40 are connected to each other in such a way that no air passage is defined between the stator and the peripheral portion that allows air to flow from one of the two chambers 36, 38 to the other, or at least no air passage that allows a large volume of air to flow is defined.

[0024] The peripheral portion 40 defines a first liquid circuit 48 configured to receive a first coolant flow 32, which is intended to be heated by heat received from the stator 16. For example, the peripheral portion 40 has two walls 50, 52 that define an internal path for the first coolant flow 32, extending from an inlet 54 to an outlet 56, both axially and about axis X. The rotor 18 defines a plurality of air passages 58 located between the two chambers 36, 38. Figure 2 (Only one is shown in the image), for example, parallel to axis X.

[0025] The heat exchanger 22 is advantageously fixed to the housing 20 via two air ducts 60, 62. The heat exchanger 22 has an air inlet 64 in fluid communication with one of the two chambers 36, 38, and an air outlet 66 in fluid communication with the other chamber, for example via the two ducts 60, 62 respectively.

[0026] The heat exchanger 22 includes a second liquid circuit 68 configured to receive a second coolant flow 34.

[0027] The heat exchanger 22 includes, for example, a housing 70 defining an internal volume 72 and a plurality of pipes 74 extending in the internal volume 72 along the liquid circulation direction C and adapted to receive a second coolant flow 34.

[0028] exist Figure 4 In the variant shown, the heat exchanger 22 advantageously includes a plurality of inner walls 76 extending in the internal volume, which are arranged sequentially along the liquid circulation direction C.

[0029] Air passage 58, two chambers 36, 38 and heat exchanger 22 define an air circuit 78 suitable for cooling rotor 18, and heat exchanger 22 is adapted to exchange heat between air in air circuit 78 and second coolant flow 34.

[0030] The fan 24 is adapted to circulate air in the air circuit 78. The fan 24 extends, for example, into one of the two chambers 36, 38.

[0031] The housing 70 and the tube 74 define a portion 80 of the air circuit 78 located between the air inlet 64 and the air outlet 66. The housing 70 has, for example, a tubular shape.

[0032] The outer casing 70 is advantageously formed with external heat sinks 82 extending parallel to the longitudinal direction L.

[0033] The direction of liquid circulation C is, for example, substantially parallel to the axis X, and therefore perpendicular to the longitudinal direction L in this example.

[0034] Each inner wall 76 is passed through by a portion of the tube 74, and a portion 80 of the air circuit 78 is partially closed in the liquid circulation direction C to define a zigzag air path in the portion.

[0035] The tube 74 may, for example, have a circular or square cross-section.

[0036] Air inlet 64 and air outlet 66 are advantageously located at two opposite ends 84, 86 of heat exchanger 22 along direction T, in this example direction T being parallel to the liquid circulation direction C. Advantageously, air inlet 64 and air outlet 66 are aligned with two chambers 36, 38 along two radial directions R1, R2 relative to axis X, respectively.

[0037] The two radial directions R1 and R2 are, for example, coplanar, and the air inlet 64 and the air outlet 66 are located on the same side of the axis X along the two radial directions R1 and R2.

[0038] In this example, the two conduits 60 and 62 extend along two radial directions R1 and R2, respectively.

[0039] like Figure 1 As shown in the upper part, the first liquid circuit 48 and the second liquid circuit 68 are connected in series with each other and connected to the coolant source 30. The second coolant flow 34 flows out of the second liquid circuit 68 to form the first coolant flow 32. This reduces the pressure drop in the coolant.

[0040] As a variant (not shown), the first coolant flow 32 flows out of the first liquid circuit 48 to form a second coolant flow 34 that enters the second liquid circuit 68.

[0041] exist Figure 1 In the variant shown in the lower half, the first liquid circuit 48 and the second liquid circuit 68 are connected in parallel to each other to the coolant source 30 to receive the first coolant flow 32 and the second coolant flow 34, respectively. This optimizes the coolant temperature at the inlet 54 of the first liquid circuit 48 and the inlet of the second liquid circuit 64.

[0042] The operation of vehicle 10, which illustrates the traction method according to the present invention, will now be briefly described.

[0043] The rotor 18 rotates about axis X relative to the stator 16, thereby providing mechanical power to the shaft 26. This mechanical power is used to drive the vehicle 10.

[0044] The outer portion 40 receives heat from the stator 16, thereby cooling the stator.

[0045] The first liquid circuit 48 receives a first coolant flow 32, which is heated by the heat received from the stator 16.

[0046] The second liquid circuit 68 receives the second coolant flow 34.

[0047] Fan 24 circulates air in air circuit 78. Rotor 18 is cooled by air circuit 78. Heat exchanger 22 exchanges heat between the air in air circuit 78 and the second coolant flow 34. More specifically, the air circulating in channel 58 is heated and then cooled in heat exchanger 22 by exchanging heat with the first coolant flow 34. Once cooled, the air circulates in channel 58 again.

[0048] Advantageously, the second coolant flow 34 and the air flow in opposite directions along the liquid circulation direction C.

[0049] In this example, the second coolant flow 34 is formed by the first coolant flow 32 exiting the heat exchanger 22. The second coolant flow 32 returns to the coolant source 30 after passing through the peripheral portion 40 for cooling.

[0050] Due to the aforementioned features, there is better thermal contact between the stator 16 and the outer periphery 40 of the housing 20, thereby enabling better cooling of the stator 16. The rotor 18 is cooled by an air circuit 78, which is efficiently cooled in the heat exchanger 22.

[0051] In this example, no air passage for the cooling air circuit 78 is required between the outer portion 40 and the stator 16, which improves the thermal contact between the stator 16 and the outer portion 40. This is beneficial for the cooling of the stator 16.

[0052] Overall, the traction system 12 has higher cooling efficiency, especially the stator 16, without reducing the cooling effect on the rotor.

[0053] Furthermore, the heat exchanger 22 can be quite compact, especially due to its optional features. Specifically, the heat sinks 82, particularly when they are parallel to the longitudinal direction L, improve the cooling effect of the air circuit 78 in the heat exchanger 22 or reduce the demand for coolant by means of the oncoming airflow generated by vehicle movement.

[0054] The optional inner wall 76 also improves cooling efficiency by enhancing heat exchange between the air and the tube 74.

Claims

1. A traction system (12) for a rail vehicle (10), characterized in that, include: An electric motor (14) includes a stator (16), a rotor (18) adapted to rotate relative to the stator about an axis (X), and a housing (20) including a peripheral portion (40) surrounding the stator (16) about the axis (X), the peripheral portion (40) being in thermal contact with the stator (16) to receive heat from the stator (16), the housing (20), the rotor (18), and the stator (16) defining two axially opposed chambers (36, 38), the rotor (18) defining a plurality of air passages (58) between the two chambers (36, 38), and the peripheral portion (40) defining a first liquid circuit (48) configured to receive a first coolant flow (32) intended to be heated by the heat received from the stator (16). A heat exchanger (22), located outside the housing (20), has an air inlet (64) in fluid communication with one of the two chambers (36, 38), an air outlet (66) in fluid communication with the other of the two chambers (36, 38), and a second liquid circuit (68) configured to receive a second coolant flow (34). The air passage (58), the two chambers (36, 38), and the heat exchanger (22) define an air circuit (78) suitable for cooling the rotor (18). The heat exchanger (22) is adapted to exchange heat between the air in the air circuit (78) and the second coolant flow (34). A fan (24) is used to circulate air in an air circuit (78).

2. The traction system (12) according to claim 1, characterized in that, The stator (16) and the peripheral portion (40) are connected to each other in such a way that there is no defined air passage between the stator (16) and the peripheral portion (40) that allows air in the air circuit to bypass the heat exchanger (22).

3. The traction system (12) according to claim 1 or 2, characterized in that, The heat exchanger (22) includes: A shell (70) defining the internal volume (72); and Multiple pipes (74) extending in the internal volume (72) along the liquid circulation direction (C) and adapted to receive a second coolant flow (34); The housing (70) and the tube (74) define a portion (80) of the air circuit (78) located between the air inlet (64) and the air outlet (66).

4. The traction system (12) according to claim 3, characterized in that, The outer shell (70) has a tubular shape.

5. The traction system (12) according to claim 3 or 4, characterized in that, The direction of liquid circulation (C) is substantially parallel to the axis (X).

6. The traction system (12) according to any one of claims 3 to 5, characterized in that, The housing (70) forms an external heat sink (82) that extends in a longitudinal direction (L) parallel to the intended travel of the vehicle (10).

7. The traction system (12) according to claim 6, characterized in that, The axis (X) is basically perpendicular to the longitudinal direction (L).

8. The traction system (12) according to any one of claims 3 to 7, characterized in that, The heat exchanger (22) includes a plurality of inner walls (76) extending in an internal volume (72), the inner walls (76) being arranged sequentially along the liquid circulation direction (C), and each inner wall (76) being traversed by a portion of a tube (74), each inner wall (76) partially closing off a portion (80) of the air circuit (78) in the liquid circulation direction (C) to define a zigzag air path in the portion (80).

9. The traction system (12) according to any one of claims 1 to 8, characterized in that, The air inlet (64) and the air outlet (66) are located at two opposite ends (84, 86) of the heat exchanger (22) in one direction (T).

10. The traction system (12) according to any one of claims 1 to 9, characterized in that, The air inlet (64) and the air outlet (66) are aligned with the two chambers (36, 38) along two radial directions (R1, R2) relative to the axis (X), respectively. The two radial directions (R1, R2) are coplanar, and the air inlet (64) and the air outlet (66) are located on the same side of the axis (X) along the two radial directions (R1, R2).

11. The traction system (12) according to any one of claims 1 to 10, characterized in that, It further includes a coolant source (30) suitable for providing a first coolant flow (32) and a second coolant flow (34).

12. The traction system (12) according to claim 11, characterized in that, The first liquid circuit (48) and the second liquid circuit (68) are connected in parallel to the coolant source (30) to receive the first coolant flow (32) and the second coolant flow (34), respectively.

13. The traction system (12) according to claim 11, characterized in that, The first liquid circuit (48) and the second liquid circuit (68) are connected in series with each other and connected to a coolant source (30). The first coolant flow (32) is intended to flow out of the first liquid circuit (48) to form a second coolant flow (34), or the second coolant flow (34) is intended to flow out of the second liquid circuit (68) to form a first coolant flow (32).

14. A rail vehicle (10), characterized in that, It includes the traction system (12) according to any one of claims 1 to 13.

15. A traction method, characterized in that, Includes the following steps: Obtain the traction system (12) according to any one of claims 1 to 13, or the rail vehicle (10) according to claim 14. The rotor (18) is rotated about the axis (X) relative to the stator (16), and the outer part (40) receives heat from the stator (16); The first liquid circuit (48) receives a first coolant flow (32), which is heated by the heat received from the stator (16); The second liquid circuit (68) receives the second coolant flow (34); The rotor (18) is cooled by an air circuit (78), and a heat exchanger (22) exchanges heat between the air in the air circuit (78) and the second coolant flow (34); and The air is circulated in the air circuit (78) by using a fan (24).

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