TRACTION DEVICE WITH INTEGRATED FAN

Description

TECHNICAL FIELD

[0001] The present invention relates to a rail vehicle with a traction device with an integrated fan. PREVIOUS STATE OF THE ART

[0002] Traction devices, for example, for use in rail vehicles, are currently predominantly powered by electric motors, especially asynchronous motors. Due to electrical resistance and friction, the stator and rotor of an electric motor generate thermal energy, or heat.

[0003] Motor cooling is typically provided by a self-ventilation system, with a fan attached to the rotor or rotor shaft of the traction motor, providing cooling air to dissipate heat. The fan rotates at the same speed and in the same direction as the rotor, which is driven at the respective speed of the electric motor.

[0004] Furthermore, arrangements for motors have already been proposed that feature a fan drive in addition to the actual motor. For example, DE 1134 453 describes such a fan drive for DC motors using a commutatorless rotating field motor that is powered by the motor to be ventilated.

[0005] DE 259034 and DE 32 40 058 A1 each disclose a device for cooling electrical machines in which a fan can run at a multiple of the speed of the machine to be cooled.

[0006] The arrangements cited above are particularly limited to low speed ranges and are therefore of only limited use for rail vehicles, which are generally operated at high speeds.

[0007] For forced ventilation of traction devices, a separate traction motor fan is usually provided, which is mounted, for example, on the roof (e.g., in low-floor vehicles) or underfloor (e.g., in high-floor vehicles). The air flow from the traction motor fan is transported to the motor via air ducts through the vehicle interior.

[0008] In US 2 613 240, a separate, relatively small cooling motor in the same housing as the electric motor is proposed for the forced ventilation of an electric motor, whereby the cooling motor rotates the fan blades at a constant speed regardless of the speed of the electric motor.

[0009] EP 1 109 297 A2 describes a forced-ventilated traction motor with a fan wheel mounted so that it can rotate freely relative to the traction motor shaft and driven by an electric fan motor. EP 2 149 712 A1 discloses a bidirectional radial fan for the traction motor of a rail vehicle. DISADVANTAGES OF THE STATE OF THE ART

[0010] Traction devices operate under regularly changing load and speed conditions and must meet high tractive and braking force requirements, making conventional self-ventilation, in which the fan is attached to the traction motor rotor, inadequate. Especially when the rotor operates at a speed where the air circulation through the fan does not provide sufficient cooling, there is a risk of the motor overheating. Therefore, self-ventilated motors are limited in their continuous thermal performance, especially at lower speeds.

[0011] For high-speed engines, the noise level in existing self-ventilation designs is usually determined by the fan. Since the ventilation of the traction motor depends on the speed of the traction motor, an upper limit is set for the speed of the traction motor to avoid excessive noise emissions.

[0012] This limitation of the traction motor's speed limits its performance. While this power limitation can be compensated for by increasing the motor diameter and thus increasing torque, this in turn increases the space required and the weight of the motor.

[0013] In addition, the direction of rotation of traction motors is usually not fixed. Since the fan, when mounted on the rotor of the traction motor, always has the same speed and direction of rotation as the traction motor, the fan must always be designed for both directions of rotation.

[0014] However, self-ventilation is often cheaper and more space-saving than conventional forced ventilation, as there is no need to install a separate traction motor fan and air ducts in the vehicle. PROBLEM STATEMENT

[0015] The object of the present invention is therefore to provide an improved traction device with an integrated fan, which combines the performance and lower noise level of a forced-ventilated motor with the smaller space requirement of a self-ventilated motor and thus in particular reduces the disadvantages described above. INVENTIVE SOLUTION

[0016] The above object is achieved by the features in claim 1. Advantageous embodiments emerge from the dependent subclaims.

[0017] According to the invention, a traction device, in particular for rail vehicles, is provided, comprising a traction motor with a motor shaft, a traction motor rotor connected in a rotationally fixed manner to the motor shaft, and a traction motor stator surrounding the motor shaft and the traction motor rotor. Furthermore, the traction device comprises a fan for ventilating the traction motor, which fan comprises an annular fan rotor having at least two radially inwardly extending fan blades and is mounted for free rotation relative to the motor shaft, and a fan stator surrounding the fan rotor.

[0018] The fan pushes or draws ambient air through the traction motor, typically in an axial direction, thereby providing cooling air to dissipate the heat generated in the traction motor. Since the fan's rotor is mounted so it can rotate freely around the shaft, neither the direction of rotation nor the rotational speed of the fan need to match the direction of rotation or the rotational speed of the traction motor.

[0019] In particular, ventilation of the traction motor is achieved which is independent of its speed, thus avoiding overheating at low speeds and high noise levels at high speeds.

[0020] The traction motor, for example, an asynchronous motor, can therefore be operated at high speeds, keeping the motor's torque and thus its weight low. The traction device according to the invention is thus not only more space-saving than a conventional forced ventilation system with a traction motor fan and air ducts, but can also be implemented with a smaller diameter than a comparable self-ventilated motor.

[0021] According to an advantageous embodiment of the invention, at least two, but in particular several, permanent magnets, for example at least three or at least four, are distributed along the annular fan rotor. The annular fan rotor can have a closed shape but can also be formed from partially annular segments, each of which is connected to at least one of the at least two fan blades.

[0022] According to one embodiment, the annular fan rotor is connected via the at least two fan blades to a rotary bearing arranged on the motor shaft and can rotate relative to the motor shaft. In an embodiment in which the fan rotor and the rotary bearing are no wider than the at least two fan blades in the axial extension of the motor shaft, the externally ventilated traction device according to the invention can be implemented in the installation space of a self-ventilated motor. In order to be able to generate the air flow required for cooling, it can be advantageous if the fan rotor has a larger radial extension than the traction motor or the traction motor rotor that is non-rotatably connected to the motor shaft.

[0023] According to one embodiment, the traction motor stator and the fan stator each have separate electrical connections, so that a rotational speed and / or direction of rotation of the fan rotor can be realized independently of a rotational speed and / or direction of rotation of the motor shaft of the traction motor.

[0024] The at least two fan blades, which are directed toward the center of the annular fan rotor, can be designed for unidirectional rotation according to one embodiment and bidirectional rotation according to another embodiment. With bidirectional rotation, it is possible to adapt the direction of rotation of the fan rotor to the direction of rotation of the traction motor rotor and thus limit the relative rotational speed of the fan rotor relative to the motor shaft (8), thereby reducing the stress on the fan pivot bearing.

[0025] According to an advantageous embodiment of the invention, the fan stator and the traction motor stator are coaxially mounted relative to a housing. The fan can accordingly be arranged on a first end face of the traction motor. Additionally, according to another embodiment, a second fan can also be arranged on a second end face opposite the first end face.

[0026] According to one embodiment, the housing can have ventilation openings, in particular axial ventilation openings, for the flow of air as well as at least one rotary bearing for supporting the motor shaft on each end face.

[0027] According to a further embodiment, a rail vehicle is disclosed, comprising a traction device according to one or more of the embodiments described above.

[0028] The embodiments described above can be combined with each other as desired. BRIEF DESCRIPTION OF THE CHARACTERS

[0029] The accompanying drawings illustrate one embodiment and, together with the description, serve to explain the principles of the invention. The elements of the drawings are relative to one another and are not necessarily to scale. Like reference numerals designate similar parts. Fig. 1 shows a side view of a traction device according to the invention, and Fig. 2 shows a front view of the ring-shaped fan rotor. EXAMPLE OF IMPLEMENTATION

[0030] Fig. 1 shows a side view of a traction device 1 according to the invention with an integrated fan 2 in cross section.

[0031] In addition to a housing 3, a drive side 4, a traction motor rotor 5 and a traction motor stator 6 of a known traction motor 7 are schematically shown.

[0032] The traction motor stator 6, including the stator winding, is fixed to the housing 3. The traction motor rotor 5, which has a motor shaft 8 and a rotor winding 10, is mounted on each end face of the housing 3 via a pivot bearing 10, 20, via the motor shaft 8.

[0033] To cool the traction motor, a fan 2 is integrated in the housing 3, which is driven by a fan stator 11 and a fan rotor 13.

[0034] The fan stator 11, including the stator winding, is axially spaced from the traction motor stator 4 and also fixed relative to the housing 3. The winding heads of the traction motor stator 4 and the fan stator 7 are preferably facing away from each other so that the magnetic fields acting upon current flow influence each other as little as possible.

[0035] The fan stator 11 surrounds the fan rotor 13 and is arranged opposite it with a small radial gap 12. The fan rotor 13 is designed as a ring with integrated permanent magnets 14 and surrounds the motor shaft 8 in a concentric manner. A front view of the ring-shaped fan rotor 13 is shown in Fig. 2 shown.

[0036] A plurality of fan blades 15 are fixed to the fan rotor 13 and extend to a fan pivot bearing 16 which is attached to the motor shaft 8 in the center of the annular fan rotor 13.

[0037] This design allows the fan rotor 13 to rotate independently of the speed of the motor shaft 8. The variable-speed bearing relative to the motor shaft 8 allows the speed of the fan 2 to be controlled independently of the speed of the traction motor 7 by applying a variable-frequency voltage. The external voltage supply to the fan 2 and the traction motor 7 is not shown. For this purpose, the fan rotor 13 is connected to an electrical connection 22, which is independent of an electrical connection 21 of the traction motor rotor 6.

[0038] The fan can thus operate at a higher speed even when the electric motor 7 is running at low speeds, providing sufficient cooling air to dissipate the heat generated in the electric motor and prevent it from overheating. The fan blades 15 can also be optimized for a specific direction of rotation, thus also optimizing the associated airflow. This can increase the performance of the fan 2 and reduce its noise emissions.

[0039] In order to keep the difference in the speeds of the motor shaft 8 and the fan rotor 13 small and thus to extend the service life of the fan pivot bearing 16, a design for both directions of rotation can also be selected.

[0040] The fan can generally be operated at a lower speed when the electric motor 7 is running at high speeds in order to avoid high noise levels.

[0041] If the annular fan rotor 13 with the integrated magnets and the fan pivot bearing 16 on the motor shaft 8 are not wider in the axial direction than a comparable fan of a self-ventilated motor, the traction device according to the invention does not require any additional space and can be accommodated in the installation space of a self-ventilated motor. List of reference symbols

[0042] 1 Traction device 2 Fan 3 Housing 4 Drive side 5 Traction motor rotor 6 Traction motor stator with stator winding 7 Electric motor 8 Motor shaft 9 Rotor winding 10 Fan pivot bearing 11 Fan stator with stator winding 12 Radial gap 13 Fan rotor with integrated permanent magnets 14 Permanent magnet 15 Fan blade 16 Pivot bearing 20 Pivot bearing 21 Connection for traction motor rotor 22 Connection for fan rotor

Claims

1. A rail vehicle including at least one traction device, the traction device comprising: a traction motor (7) including a motor shaft (8), a traction motor rotor (5) connected in a rotationally fixed manner to the motor shaft (8), and a traction motor stator (6) surrounding the motor shaft (8) and the traction motor rotor (5), and a fan (2) for ventilating the traction motor, comprising an annular fan rotor (13) which comprises at least two fan blades (15) extending radially inwards and is freely rotatably mounted relative to the motor shaft (8), and a fan stator (11) surrounding the fan rotor (13), wherein the at least two fan blades (15) are connected to the motor shaft (8) via a fan pivot bearing (16) arranged on the motor shaft (8).

2. The rail vehicle according to claim 1, wherein the fan rotor (13) comprises at least two, in particular a plurality of permanent magnets (14) distributed along the annular fan rotor (13).

3. The rail vehicle according to claim 1 or 2, wherein the traction motor stator (6) and the fan stator (11) each comprise separate electrical connections (21, 22) in order to set a rotational speed and / or direction of rotation of the fan rotor (13) independently of a rotational speed and / or direction of rotation of the motor shaft of the traction motor (5).

4. The rail vehicle according to any one of claims 1 to 3, wherein the at least two fan blades (15) are configured for a unidirectional direction of rotation.

5. The rail vehicle according to any one of claims 1 to 3, wherein the at least two fan blades (15) are configured for a bidirectional direction of rotation.

6. The rail vehicle according to any one of claims 1 to 5, comprising a housing (3), wherein the fan stator (11) and the traction motor stator (6) are fixed in and relative to the housing (3), in particular that the fan stator (11) is fixed to the housing (3) independently of the traction motor stator (6) and, in particular, axially spaced therefrom.

7. The rail vehicle according to claim 6, wherein the housing (3) comprises ventilation openings, in particular axial ventilation openings, for air to flow through.

8. The rail vehicle according to claim 6 or 7, wherein the housing (3) comprises at least one pivot bearing (10, 20) on each of its end faces for supporting the motor shaft (8).

9. The rail vehicle according to any one of the preceding claims, wherein the fan rotor (13) and the fan pivot bearing (16) are not wider than the at least two fan blades (15) in the axial extension of the motor shaft (8).

10. The rail vehicle according to any one of the preceding claims, wherein the fan rotor (13) of the fan (2) is formed from partially annular segments, each of which is connected to at least one of the at least two fan blades (15).

11. The rail vehicle according to any one of the preceding claims, wherein the traction motor (7) is an asynchronous motor.

12. The rail vehicle according to any one of the preceding claims, wherein the fan (2) is arranged on a first end face of the traction motor (7).

13. The rail vehicle according to claim 12, further comprising a second fan arranged on a second end face of the traction motor (7) opposite the first end face.