Electric traction motor with cooling device for vehicle

Abstract

The invention relates to an electric traction motor (10) comprising: a motor shaft (12); the rotor (14) is fixed on the motor shaft; a stator (16) connected to the rotor; and a motor frame (18) fixed on the stator. The first end (22) and the second end (24) of the motor shaft are located outside the motor frame. The motor shaft comprises:-a main channel (52) extending between a first end and a second end of the motor shaft; and-a plurality of secondary channels (54) connected to one end (60) of the primary channel. The motor further comprises a fan (19) mounted at the second end of the motor shaft so as to generate an air flow through the main channel and the secondary channel.

Description

TECHNICAL FIELD

[0001] The present invention relates to an electric traction motor comprising a motor shaft extending along a main axis between a first end and a second end, a rotor surrounding the motor shaft and fixed thereto, a stator associated with the rotor, and a motor frame fixed to the stator, the motor shaft being able to rotate about the main axis with respect to the motor frame. The motor frame delimits an inner chamber which houses the rotor and the stator, the first end and the second end of the motor shaft being located outside the inner chamber. The motor shaft comprises a main channel extending through the inner chamber along the main axis, a first end of the main channel being open at the first end of the motor shaft, a second end of the main channel being located at the second end of the motor shaft, and a plurality of secondary channels connected to the second end of the main channel and extending through the second end of the motor shaft.

[0002] More precisely, the present invention relates to the temperature regulation of an electric traction motor. BACKGROUND

[0003] The rotation of the rotor generates energy losses which cause an increase in temperature inside the motor, in particular for a motor of the enclosed type. This temperature increase can cause malfunctions of the motor.

[0004] In particular, for a motor provided with bearings, it is necessary to control the temperature of the bearings to ensure proper lubrication.

[0005] It is known to provide an electric traction motor provided with a cooling device which involves a heat transfer fluid. Document US 2 436 320 discloses an electric motor of the above-mentioned type, the cooling device of which involves an air flow. SUMMARY

[0006] The aim of the present invention is to provide a motor provided with an improved cooling device.

[0007] To this end, the present invention relates to a motor of the above-mentioned type, further comprising a fan mounted at the second end of the motor shaft so as to generate an air flow through the main channel and the secondary channels between the first end and the second end of the motor shaft.

[0008] According to a preferred embodiment, the motor can comprise one or more of the following features, alone or in any technically possible combination:

[0009] - the second end of the motor shaft comprises a radial surface parallel to the main axis, one end of each secondary channel being open on the radial surface;

[0010] - the electric traction motor further comprises at least one bearing assembly located between the motor shaft and the motor frame, said bearing assembly being located between the first end and the second end of the main channel with respect to the main axis;

[0011] - the electric traction motor further comprises a sealing device for the bearing assembly, the sealing device comprising a first and a second set of coaxial rings forming a baffle, the first and second sets being fixed respectively to the motor shaft and to the motor frame, and a support fixed to a radial surface of the second end of the motor shaft, wherein the first set of coaxial rings extends axially from the support and the fan extends radially from the support;

[0012] - the support comprises a plurality of radial holes, each radial hole extending from one end of one of the secondary channels;

[0013] - each radial hole is located between the first set of coaxial rings and the fan with respect to the main axis;

[0014] - the sealing device further comprises a third and a fourth set of coaxial rings forming a baffle, the third and fourth sets being fixed respectively to the motor shaft and to the motor frame, the third and fourth sets being located inside the inner chamber delimited by the motor frame;

[0015] - the inner chamber delimited by the motor frame is a closed space.

[0016] The present application also relates to a vehicle comprising a vehicle body and an electric traction motor as described above mounted on the vehicle body. BRIEF DESCRIPTION OF DRAWINGS

[0017] The present application will be more readily understood by referring to the following description in conjunction with the accompanying drawings in which:

[0018] - Figure 1 is a cross-sectional view of a vehicle comprising an electric traction motor according to one embodiment of the present application;

[0019] - Figure 2 is a detailed view of the electric traction motor of Figure 1 . DETAILED DESCRIPTION

[0020] Figure 1 An electric traction motor 10 according to one embodiment of the present application is shown. Preferably, the motor 10 is a traction motor of a railway vehicle. More preferably, the motor 10 is mounted on a bogie 11 of a railway vehicle.

[0021] As shown in Figure 1 , the motor 10 comprises a motor shaft 12, a rotor 14, a stator 16 and a motor frame 18. The motor 10 further comprises a fan 19 mounted on the motor shaft 12.

[0022] The motor shaft 12 extends along a main axis 20 between a first end 22 and a second end 24.

[0023] The rotor 14 extends around and is fixed to the motor shaft 12. In one embodiment, the rotor 14 comprises metal laminations inserted around the motor shaft 12 and stacked along the main axis 20.

[0024] The stator 16 comprises a tubular stator core coaxial with the main axis 20, which is arranged around the rotor 14.

[0025] In the embodiment shown in Figure 1 and Figure 2 , the motor frame 18 comprises a main body 30 and a first flange 32 and a second flange 34. The main body comprises a substantially cylindrical inner surface extending along the main axis 20 and fixed to the stator 16.

[0026] The first flange 32 and the second flange 34 are fixed to a first end and a second end of the main body 30, respectively, with respect to the main axis 20. The motor frame 18, and more precisely the main body 30 and the first flange 32 and the second flange 34, delimit an inner chamber 35 which houses the rotor 14 and the stator 16.

[0027] According to one embodiment, the motor 10 is a closed motor and the inner chamber is a closed space. According to another embodiment (not shown), the motor is an open motor and the motor frame comprises air vents opening to the inner chamber.

[0028] The first flange 32 and the second flange 34 each comprise an axial opening 36, 38. The first end 22 and the second end 24 of the motor shaft 12 extend axially through the axial openings 36, 38 of the first flange 32 and the second flange 34, respectively. Thus, the first end 22 and the second end 24 of the motor shaft are located outside the inner chamber 35.

[0029] The motor shaft 12 is rotatable with respect to the motor frame 18 around the main axis 20. In the embodiment shown in Figure 1 and Figure 2 , the motor 10 comprises a first bearing assembly 40 and a second bearing assembly 42 which allow the motor shaft 12 to rotate with respect to the first flange 32 and the second flange 34. The first bearing assembly 40 and the second bearing assembly 42 are axially arranged between the rotor 14 and the first end 22 and the second end 24 of the motor shaft 12, respectively.

[0030] In the embodiment shown in Figure 1 and Figure 2 , the motor 10 further comprises a sealing device 44, 46 associated with each bearing assembly 40, 42, and a support 48 fixed to the second end 24 of the motor shaft.

[0031] The motor shaft 12 will now be described in more detail. As shown in Figure 2 , the motor shaft 12 comprises a body 50, a main channel 52, and a plurality of secondary channels 54.

[0032] The body 50 extends along the main axis 20 and is bounded by a radial surface, preferably an annular surface around the main axis 20. In particular, the radial surface of the body 50 comprises a cylindrical surface 56 at the second end 24 of the motor shaft 12.

[0033] The main channel 52 extends within the body 50 along the main axis 20 between a first end 58 and a second end 60. The first end 58 of the main channel 52 is open at the first end 22 of the motor shaft. The main channel 52 is thus connected on the side of the first flange 32 to the outside of the motor 10.

[0034] The main channel 52 passes through the inner chamber 35. The second end 60 of the main channel is a closed end located within the second end 24 of the motor shaft 12. Preferably, the cylindrical surface 56 of the second end 24 is arranged around the second end 60 of the main channel.

[0035] Each first bearing assembly 40 and second bearing assembly 42 is located relative to the main axis 20 between the first end 58 and the second end 60 of the main channel 52.

[0036] Each secondary channel 54 extends from the second end 60 of the main channel 52 and is open on the cylindrical surface 56 of the second end 24. The main channel 52 is thus connected on the side of the second flange 34 to the outside of the motor 10.

[0037] In the embodiment shown in Figure 1 and Figure 2 each secondary channel 54 is perpendicular relative to the main axis 20. In another embodiment (not shown), each secondary channel 54 is obliquely inclined relative to the main axis 20.

[0038] Preferably, the motor shaft 12 comprises a number of secondary channels 54 between 2 and 12.

[0039] The fan 19 is mounted on the second end 24 of the motor shaft 12. In the embodiment shown in Figure 1 and Figure 2 the opening of the secondary channel 54 on the cylindrical surface 56 is located between the second flange 34 and the fan 19, relative to the main axis 20.

[0040] The support 48 is arranged around the second end 24 of the motor shaft 12, preferably annularly. In the embodiment shown in Figure 1 and Figure 2 the support 48 is fixed to or integral with the fan 19. The fan 19 extends radially from the support 48.

[0041] More particularly, in the embodiment shown in Figure 1 and Figure 2 the support 48 is mounted on the cylindrical surface 56 of the second end 24 and comprises a plurality of radial holes 62. Each radial hole 62 extends in one of the secondary channels 54 of the motor shaft 12.

[0042] The sealing device 46 associated with the second bearing assembly 42 will now be described in more detail. The sealing device 46 comprises a first set 64 and a second set 66 of coaxial rings. The rings of the first set 64 and the second set 66 are alternately arranged in a radial direction, forming a baffle. The coaxial rings of the first set 64 and the second set 66 are fixed to the motor shaft 12 and the motor frame 18, respectively.

[0043] The first set 64 is thus able to rotate with respect to the second set 66 about the main axis 20. The baffle formed by the coaxial rings of the first set 64 and the second set 66 protects the second bearing assembly 42 from contamination from outside the motor 10.

[0044] In the embodiment shown in Figure 1 and Figure 2 The coaxial rings of the first set 64 axially extend from the support 48 towards the inner chamber 35. In other words, the radial holes 62 of the support 48 are located between the coaxial rings of the first set 64 and the fan 19, with respect to the main axis 20.

[0045] Preferably, the coaxial rings of the first set 64 are integrally formed with the support 48.

[0046] In the embodiment shown in Figure 1 and Figure 2 The sealing device 46 associated with the second bearing assembly 42 further comprises a third set 70 and a fourth set 72 of coaxial rings forming a baffle, the third set 70 and the fourth set 72 being fixed to the motor shaft 12 and the motor frame 18, respectively. The coaxial rings of the third set 70 and the fourth set 72 are located inside the inner chamber 35. The baffle formed by the coaxial rings of the third set 70 and the fourth set 72 protects the second bearing assembly 42 from contamination by the rotor 14.

[0047] Preferably, the sealing device 44 associated with the first bearing assembly 40 has a similar shape as the sealing device 46 described above.

[0048] The method of operation of the motor 10 will now be described.

[0049] The rotation of the motor shaft 12 with respect to the motor frame 16 causes the rotation of the fan 19. The rotation of the fan creates a pressure difference between the side of the first flange 32 and the side of the second flange 34. Fresh air from outside the motor 10 is drawn into the first end 58 of the main channel 52 and is expelled in the vicinity of the fan 19 through the radial holes 62 of the support 48.

[0050] The airflow through the main channel cools the body 50 of the motor shaft 12 by heat conduction. The bearing assemblies 40, 42 and the rotor 14, which are in thermal contact with the body 50, are also cooled by the airflow.

[0051] Accordingly, the temperature of the rotor 14 and bearing assemblies 40, 42 is maintained at an acceptable level to allow the motor 10 to operate.

[0052] The present application avoids the use of a pump required in cooling devices involving heat transfer liquids.

Claims

1. An electric traction motor (10), comprising: - Motor shaft (12), which extends along the main axis (20) between the first end (22) and the second end (24); - Rotor (14), which extends around the motor shaft and is fixed to the motor shaft; - Stator (16), which is connected to the rotor; and - Motor frame (18), which is fixed to the stator, and the motor shaft can rotate about the main axis relative to the motor frame. The motor frame defines an inner cavity (35) that houses the rotor and stator, with the first and second ends of the motor shaft located outside the inner cavity; The motor shaft includes: - A main channel (52) extending along the main axis through the inner cavity, the first end (58) of the main channel opening at the first end of the motor shaft, and the second end (60) of the main channel located at the second end (24) of the motor shaft; and - Multiple secondary channels (54) are connected to the second end (60) of the main channel and extend through the second end of the motor shaft; The electric traction motor is characterized in that it also includes a fan (19) mounted on the second end of the motor shaft to generate airflow through the main channel (52) and the secondary channel (54) between the first end (22) and the second end (24) of the motor shaft.

2. The electric traction motor according to claim 1, characterized in that: - The second end (24) of the motor shaft includes a radial surface (56) parallel to the main axis; and - One end of each sub-channel (54) opens on the radial surface.

3. The electric traction motor according to claim 1 or 2, comprising at least one bearing assembly (40, 42) located between the motor shaft and the motor frame, the bearing assembly being located between a first end (58) and a second end (60) of the main channel (52) relative to the main axis (20).

4. The electric traction motor according to claim 2 in conjunction with claim 3, further comprising: - A sealing device (46) for the bearing assembly (42), the sealing device comprising a first set (64) and a second set (66) of coaxial rings forming a baffle, the first set and the second set being fixed to the motor shaft (12) and the motor frame (18), respectively; and - Support member (48), which is fixed on the radial surface (56) of the second end (24) of the motor shaft; The first set (64) of coaxial rings extends axially from the support (48), and the fan (19) extends radially from the support.

5. The electric traction motor according to claim 4, characterized in that, The support (48) includes a plurality of radial holes (62), each of which extends from one end of one of the sub-channels (54).

6. The electric traction motor according to claim 5, characterized in that, Each radial hole (62) is located between the first set (64) coaxial ring and the fan (19) relative to the main axis (20).

7. The electric traction motor according to any one of claims 4 to 6, characterized in that, The sealing device also includes a third group (70) and a fourth group (72) of coaxial rings forming a baffle, the third group and the fourth group being fixed on the motor shaft (12) and the motor frame (18) respectively, and the third group and the fourth group being located in the inner cavity (35) defined by the motor frame.

8. The electric traction motor according to any one of the preceding claims, characterized in that, The inner chamber (35) defined by the motor frame (18) is a closed space.

9. A vehicle comprising a body (11) and an electric traction motor (10) according to any one of the preceding claims, the electric traction motor being mounted on the body.

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