Powertrain for a rail vehicle

Abstract

The invention relates to a drive train for a rail vehicle (1). It comprises a traction motor (21) designed as a permanent magnet excited synchronous machine and a wheelset (17) of the rail vehicle (1) that can be driven by it. The traction motor (21) comprises an active part with a stator (24) and a rotor (25), a motor housing (30) with a cylindrical housing shell (31) in which the stator (24) is fixed in a rotationally fixed manner, and bearing shields (32A, 32B) covering the end faces of the housing shell (31), an interior space (33) arranged in the motor housing (30) and encapsulated against an environment (U) in which at least the rotor (25) is arranged, a motor shaft (35) rotatably mounted in the bearing shields (32A, 32B) on which the rotor (25) is rotatably mounted via freewheel bearings (38), and a cooling device (40) for dissipating heat loss generated in the active part by means of a coolant flowing through cooling channels (41, 56, 57, 58).According to the invention, the drive train comprises a coupling (43) arranged within the encapsulated interior (33) for transmitting torque from the rotor (25) to the motor shaft (35), wherein the coupling (43) is switchable between an open position, in which no torque can be transmitted between the rotor (25) and the motor shaft (35), and a closed position, in which torque can be transmitted. This allows the power and torque density of the drive train to be increased.

Description

[0001] The invention relates to a drive train for a rail vehicle according to the preamble of claim 1. The invention further relates to a bogie for a rail vehicle with such a drive train. The invention also relates to a rail vehicle with such a bogie.

[0002] Such a drive train for a rail vehicle comprises a traction motor designed as a permanent magnet synchronous machine. The traction motor has an active part with a stator and a rotor. Furthermore, the traction motor has a motor housing with a cylindrical casing in which the stator is fixed against rotation, and bearing shields covering the ends of the casing. At least the rotor is arranged in an interior space within the motor housing, which is encapsulated from the environment. The traction motor has a motor shaft rotatably mounted in the bearing shields, on which the rotor is rotatably mounted via freewheel bearings. The traction motor also has a cooling system for dissipating waste heat generated in the active part by means of an external coolant flowing through cooling channels separated from the encapsulated interior. The drive train also includes a wheelset of the rail vehicle driven by the traction motor.

[0003] Due to their high achievable power and torque density, permanent magnet synchronous machines are frequently used as traction motors in rail vehicles, as the installation space for integrating a traction motor into the bogie of a rail vehicle is very limited. A disadvantage is that the magnetic excitation of the rotor by the permanent magnets cannot be switched off. Therefore, if, for example, the drive converter fails, the traction motor, due to the remaining excitation, will operate as a generator during the operation of the rail vehicle, producing electrical energy. However, it is essential to prevent this energy from being fed back into the grid and causing damage to the traction motor or the drive converter. To achieve this, it is known to interrupt the electrical connection between the traction motor and the drive converter using contactors. These contactors are integrated as additional components within the drive converter.The disadvantage is that the contactors must be controlled reliably and that they require additional installation space.

[0004] German patent application DE 10 2015 215 576 A1 discloses a drive train for a rail vehicle comprising a traction motor designed as a permanent magnet synchronous machine with a drive shaft, a switchable clutch, and a wheelset axle. The switchable clutch is arranged between one end of the drive shaft and a gearbox or between the gearbox and the wheelset axle. The switchable clutch can be designed as a multi-plate clutch or as an electromagnetically engaged gear clutch. In the event of a fault, the switchable clutch disconnects the traction motor from the drive train. With the mechanical connection broken, the traction motor coasts to a standstill and can therefore no longer generate power.

[0005] Patent EP 3 350 904 B1 discloses a connecting device by which a rotor of a permanent magnet synchronous machine, rotatably mounted on a motor shaft, is connected to the motor shaft. The connecting device comprises a first coupling part, which is fixedly mounted on the motor shaft, a second coupling part, which is fixedly connected to the rotor, and a retaining element axially penetrating the rotor and the first and second coupling parts. By means of the retaining element, the first coupling part is initially pressed axially against the second coupling part, so that a torque generated by the interaction of the stator winding and the permanent magnets is transmitted from the first and second coupling parts to the motor shaft.The retaining element consists at least partially of a material whose strength and / or cohesion is reduced in the event of a short circuit of the stator winding due to overheating of the stator winding and / or arcing to such an extent that the pressure exerted by the retaining element on the first and second coupling parts is reduced to such an extent that it allows the first and second coupling parts to be moved away from each other.

[0006] Patent EP 3 469 692 B1 discloses a rail vehicle with a drive train and a wheelset, which can be driven by an electric machine. In the event of a fault in the electric machine, the electric machine can be disconnected from the wheelset by means of an overload coupling of the drive train. For the fault triggered by a release device of the electric machine, a braking element, for example a permanent magnet or a soft magnetic element, is provided, which extends from a rotor of the electric machine into the air gap of the electric machine.

[0007] German patent application DE 10 2021 208 388 A1 discloses a drive system for a rail vehicle, comprising power converters for supplying electrical energy to traction motors. The traction motors are exclusively designed as air-cooled, permanent magnet synchronous machines and are intended for driving associated wheelset axles. The drive system also includes switchable couplings that can be arranged between a motor shaft of the traction motor and the wheelset axle, or between the motor shaft and an input shaft of a gearbox, or, if the gearbox is multi-stage, between a first and a second stage of the gearbox. Finally, it includes a control device for function- and / or situation-dependent control of the couplings and / or the power converters.If a fault is detected in one of the drive motors, the coupling is opened or, additionally, the power supply to the affected drive motor from the converter is interrupted. This prevents the formation of gases or flames and thus protects both the drive motor from potential damage and the surrounding area, without the need for additional contactors between the converters and drive motors.

[0008] The drive arrangement for a wheelset disclosed in publication EP 4 227 185 A1 comprises a permanent magnet synchronous machine with a machine housing and a shaft rotatably mounted in the machine housing about an axis. The drive arrangement includes a torque transmission system connecting the shaft to the wheelset. The torque transmission system comprises a switchable clutch with a sleeve arranged around the shaft, a first disc fixed to the shaft, a second disc mounted on the sleeve, and an actuating system for moving the second disc between an engaged position and a disengaged position. The second disc is mounted so as to be displaceable relative to the first disc parallel to the axis. In the engaged position, the first and second discs are fixedly connected with respect to the axis, while in the disengaged position, the first disc is freely rotatable about the axis relative to the second disc.The torque transmission system further comprises a reduction gear downstream of the clutch for transmitting torque to the wheelset axle. The machine housing includes a housing shell extending substantially parallel to the axle and at least one first end flange terminating the housing shell. A fixed stator and a rotor mounted on the shaft are arranged inside the machine housing. The first end flange, by its concave shape, defines a substantially cylindrical receiving space located outside the interior of the machine housing, in which the first disk, the second disk, and the actuation system are arranged. The housing shell of the machine housing radially surrounds the receiving space.

[0009] The known separable couplings, whether designed as switching or overload couplings, occupy valuable installation space due to their arrangement between the drive motor and the wheelset, possibly before or after an intermediate gearbox or before or after an intermediate cardan coupling, which has a detrimental effect on the power and torque density of the entire drive train.

[0010] The invention is therefore based on the objective of providing a drive train of the type mentioned at the outset, which is improved in particular with regard to its power and torque density compared to the known solutions.

[0011] The problem is solved by a generic drive train with the features specified in the characterizing part of claim 1.

[0012] The invention relates to a drive train for a rail vehicle, for example, for a high-speed or regional train, a locomotive, a metro, or a tram or light rail vehicle. The drive train comprises a traction motor, which is in particular designed as a permanent magnet synchronous machine. The traction motor has an active part with a stator comprising a stator lamination stack with an embedded stator winding, and a rotor comprising a rotor lamination stack with embedded permanent magnets. Furthermore, the traction motor has a motor housing with a cylindrical housing shell in which the stator is fixed against rotation, and bearing shields covering the ends of the housing shell. A first, A-side bearing shield is located on the drive or A-side of the machine, and a second, B-side bearing shield is located on the opposite, non-drive or B-side of the machine.The rotor is located within an interior space enclosed within the motor housing and encapsulated from the environment. This encapsulation forms an interior space for the traction motor that is protected from dirt, moisture, and foreign matter from the environment. The stator may also be located within this encapsulated interior space. The traction motor has a motor shaft rotatably mounted in the end shields, on which the rotor is rotatably mounted via freewheel bearings. The motor shaft and rotor are rotatable about an axis, which is the reference made in this application when the term "axial" is used. Furthermore, the traction motor has a cooling system for dissipating waste heat generated in the active part by means of coolant flowing through cooling channels. The cooling system may include cooling channels for an internal cooling circuit within the encapsulated interior space of the motor housing, as well as cooling channels through the motor housing and / or stator for an external cooling circuit, which also cools a coolant from the internal cooling circuit.

[0013] The drive train also includes a wheelset of the rail vehicle driven by the traction motor. The wheelset has an axle with two wheel discs that roll on the rails of a track traversed by the rail vehicle. The axle is rotatably mounted in two axle bearings, upon which a bogie frame of the rail vehicle's bogie rests via primary suspension. The traction motor is also at least partially supported by the bogie frame. Additional drive trains or even unpowered wheelsets may be integrated into the bogie. The vehicle body of the rail vehicle, for example, a car or locomotive body, is in turn supported by secondary suspension on the bogie. The vehicle body may also rest upon other bogies.A multiple unit train can, for example, consist of a group of coupled carriages whose car bodies are supported on bogies, several or all of which are equipped with drive trains. This allows the train to continue operating in redundancy mode with the remaining drive trains if one drive train fails, or an unused drive train can be switched off during partial load operation.

[0014] According to the invention, the drive train comprises a clutch arranged within the encapsulated interior for transmitting torque from the rotor to the motor shaft. The clutch is switchable between an open position, in which no torque can be transmitted between the rotor and motor shaft, and a closed position, in which torque can be transmitted. Compared to the prior art, the relocated clutch interface between the rotor and motor shaft and the integration of the clutch into the encapsulated interior of the motor housing save installation space for the drive train. Additionally, a separate clutch housing is no longer required to protect the switchable clutch from environmental influences, as the encapsulation seals the interior against the ingress of dirt, detergents / water, water, snow, dust, etc.Reducing the installation space required for the traction motor and the switchable clutch thus increases the power and torque density of the drive train according to the invention. The clutch is preferably arranged between the rotor and the B-side bearing shield; however, another identical switching clutch can also be arranged between the rotor and the A-side bearing shield if this is necessary due to the torques to be transmitted and if sufficient installation space is available. The drive train according to the invention, with a switchable clutch integrated into the traction motor, also enables controlled decoupling of the rotor from the rotating wheelset and, if necessary, from a gearbox, should this be required for operational reasons or in the event of a fault, in order to prevent the undesired generator operation of the synchronous machine – without the use of motor disconnect contactors or other shear devices for overload clutches provided for in the prior art.

[0015] In an advantageous embodiment of the drive train according to the invention, the clutch comprises a first clutch disc non-rotatably connected to the rotor and a second clutch disc non-rotatably connected to the motor shaft. Both the first and second clutch discs have spur gears facing each other on their end faces. The first clutch disc is axially displaceable relative to the second clutch disc, or vice versa, such that the spur gears are disengaged in the open position of the clutch and engaged in the closed position to transmit torque.On the facing end faces of the first and second clutch discs, radially extending tooth flanks are formed on an annular surface. These flanks can be positively engaged or disengaged by sliding the first and second clutch discs relative to each other. Such a toothed coupling can reliably transmit very high torques.

[0016] In a further advantageous embodiment of the drive train according to the invention, the clutch comprises a magnetic body, magnetizable by means of an excitation coil, for generating an axially acting magnetic force on the axially displaceable first or second clutch disc, and a mechanical spring device for generating an axially acting spring force on the axially displaceable first or second clutch disc. For switching the clutch, an excitation current flowing through the excitation coil can be switched on and off via a control device. If a defect in a traction motor or in a drive inverter supplying it is detected, or if a drive train is taken out of service by switching to partial load operation, the control device controls the supply of the excitation current in order to move the clutch from the closed to the open state by energizing or switching off the excitation coil.The axially acting magnetic force is generated by switching on the excitation current, which is preferably routed to the excitation coil without slip rings. As this current flows through the excitation coil, it generates a magnetic field in the magnet body. This field is then absorbed by one of the clutch discs to attract the other clutch disc. The magnetic force overcomes an axially acting tensile or compressive force between the clutch discs, generated by the mechanical spring mechanism. Depending on the clutch design, this force holds the clutch discs in either the closed or open position.

[0017] In a further advantageous embodiment of the drive train according to the invention, the axially displaceable first clutch disc has an inner radial toothing that engages with an outer radial toothing on a rotor carrier supporting the rotor. The spring assembly comprises at least one tension spring, the spring force of which pulls the axially displaceable first clutch disc away from the second clutch disc, so that the clutch assumes its open state when the excitation current is switched off and its closed state when the excitation current is switched on due to the acting magnetic force. The radial toothing ensures that the first clutch disc is rotationally fixed to the rotor via the rotor carrier by means of the interlocking of the outer and inner teeth, and is axially displaceable relative to the rotor and thus also relative to the second clutch disc.In this first embodiment, the clutch remains engaged as long as the excitation current is switched on, since the magnetic force pulls the axially displaceable first clutch disc against the second clutch disc, overcoming the opposing tensile force of the tension spring. To open the clutch, the excitation current must be switched off, so that after the magnetic force ceases, the spring force of the spring assembly pulls the first clutch disc away from the second clutch disc to disengage the spur gears. An advantage of this first embodiment is its fail-safe operation, since the clutch opens when the excitation current fails, preventing unintended regenerative operation of the machine.

[0018] In further advantageous embodiments of a second and third embodiment of the drive train according to the invention, the axially displaceable second clutch disc has an inner radial toothing which engages with an outer radial toothing on a support disc fixedly connected to the motor shaft. In these embodiments, the radial toothing ensures that the second clutch disc is rotationally fixed to the motor shaft via the support disc by means of the interlocking of the outer and inner teeth, and is axially displaceable relative to the support disc and also relative to the first clutch disc.

[0019] In the second embodiment, the spring assembly comprises at least one bistable disc spring with two stable tilting states in which the spring force acts axially in opposite directions. In a first tilting state of the disc spring, the spring force presses the axially displaceable second clutch disc against the first clutch disc, so that the clutch assumes its closed state when the excitation current is switched off. By switching on the excitation current, the at least one disc spring tilts into a second tilting state due to the generated magnetic force. In this second tilting state, the spring force pulls the axially displaceable second clutch disc away from the first clutch disc, and the clutch remains in the open state even when the excitation current is switched off again.To maintain the closed position of the clutch, the excitation coil in this second embodiment does not need to be energized, thus preventing any heat losses in the coil winding during torque transmission. A further advantage is that the clutch can be opened by briefly building up the magnetic field and is then held securely open by the tilted disc springs even when the magnetic field is absent. The clutch can be manually reset to the closed position. Likewise, in the event of a power failure to the excitation coil, the closed clutch can be manually released to its open position.

[0020] In a third embodiment, the spring assembly comprises at least one compression spring whose spring force presses the axially displaceable second clutch disc against the first clutch disc, so that the clutch assumes its closed state when the excitation current is switched off and its open state due to the acting magnetic force when the excitation current is switched on. The compression springs press the axially displaceable second clutch disc against the first clutch disc, thereby causing the clutch to assume its closed state. The excitation coil is not energized in this third embodiment, which is energetically advantageous. By energizing the excitation coil, the generated magnetic force pulls the second clutch disc away from the first clutch disc against the spring force to open the clutch.The excitation current for closing the clutch is switched off when the speeds of the clutch discs are synchronized or when the vehicle is stationary, in order to allow the face teeth to engage again.

[0021] In a further advantageous embodiment of the drive train according to the invention, the cooling device has an internal cooling circuit extending within the encapsulated interior, with first cooling channels passing through the rotor for guiding a cooling medium. The cooling medium is conveyed by an integrated fan that is rotationally fixed to the rotor or the motor shaft. The first cooling channels preferably extend axially through the rotor in the region of its circumference. The cooling medium, for example, cooling air, is circulated in the internal cooling circuit by an integrated fan located on the B-side or the A-side of the rotor. This cooling airflow supports the thermal decoupling of the coupling, particularly from the energized stator, during operation of the synchronous machine, in which electrical heat losses occur in the stator winding and losses in the stator lamination stack.An effective cooling device allows the use of synchronous machines with a high number of poles, for example 6 or 8 poles, thereby increasing the power and torque density of the drive train according to the invention.

[0022] In a further advantageous embodiment of the drive train according to the invention, fan blades are arranged on the circumference of the first clutch disc and / or the support disc. The fan blades can be designed as axially and radially extending ribs and ensure a cooling airflow by means of air turbulence in the area of ​​the clutch and the adjacent bearing shield.

[0023] In a further advantageous embodiment of the drive train according to the invention, the magnet body with excitation coil is thermally coupled to a bearing shield. By mounting the excitation coil with magnet body, for example, on the B-side bearing shield, these coupling components are additionally cooled from the outside by the airflow under the floor during operation of the rail vehicle, so that the heat losses generated when the excitation coil is energized can also be dissipated in this way.

[0024] The following embodiments describe second, third, and fourth cooling channels that extend outside the encapsulated interior of the motor housing and therefore, in the terminology of this application, form external cooling circuits. These external cooling channels serve not only to dissipate waste heat from the stator but also, in particular, to recool the cooling medium circulating in the internal cooling circuit within the encapsulated interior. These cooling channels can extend through the housing shell in the axial direction and / or circumferential direction and can also extend outside the motor housing to form a closed cooling circuit. This contributes to increasing the power and torque density of the drive train according to the invention.

[0025] In a further advantageous embodiment of the drive train according to the invention, the cooling device has second cooling channels for guiding cooling air as a coolant. The cooling air can be drawn through the second cooling channels by a fan rotating with the motor shaft outside the encapsulated interior, thus providing self-ventilation. Alternatively, the cooling air can be drawn through the second cooling channels by a fan located outside the motor housing, thus providing forced ventilation.

[0026] In a further advantageous embodiment of the drive train according to the invention, the cooling device has third cooling channels for guiding a first coolant. The first coolant can be pumped through the third cooling channels by means of a first coolant pump. Third cooling channels running within the housing jacket can form a water jacket cooling system.

[0027] In a further advantageous embodiment of the drive train according to the invention, the cooling device has a fourth cooling channel for conveying a second coolant and a canned tube arranged in an annular gap between the stator and rotor. Within the motor housing, the canned tube separates the encapsulated interior, in which the rotor is located, from an outer chamber, in which the stator is located, in a coolant-tight manner. The second coolant can be pumped through the fourth cooling channels by means of a second coolant pump and flows from the inlets of the third cooling channels into the outer chamber. After flowing around / through the stator, it exits the outer chamber through the outlets of the third cooling channels. The second coolant can be formed from transformer oil, which, as it flows through the outer chamber, directly cools the stator and also absorbs waste heat from the adjacent internal cooling circuit.Outside the motor housing, the second coolant is cooled again before the second coolant pump pumps it back into the external space. This particularly effective direct cooling enables the use of more powerful synchronous motors, which can significantly increase the power and torque density of the drive train according to the invention.

[0028] In a further advantageous embodiment of the drive train according to the invention, the motor shaft of the traction motor is coupled to the driven wheelset via a gearbox. The gearbox can, for example, be designed as a wheelset-mounted gearbox on a semi-suspended traction motor. Depending on the reduction ratio to be used between the rotational speeds of the motor shaft and the wheelset shaft, the gearbox can be designed as a single-stage or multi-stage unit.

[0029] In a further advantageous embodiment of the drive train according to the invention, the motor shaft is coupled to a transmission input shaft of the gearbox via a cardan coupling. The cardan coupling can be, for example, a curved-tooth coupling or a multi-plate coupling and serves to compensate for radial and / or angular misalignment between the motor shaft and the transmission input shaft.

[0030] In a further advantageous embodiment of the drive train according to the invention, the motor shaft of the traction motor is hollow cylindrical and surrounds the wheelset axle coaxially. The traction motor is designed as a gearless direct drive and drives the wheelset by means of a hollow cardan shaft coupling. The traction motor is thus arranged around the wheelset axle, which extends through a hollow shaft of the rotor.

[0031] Further features and advantages of the invention will become apparent from the following description of specific embodiments with reference to the drawings, in which Fig. 1 a rail vehicle according to the invention in side view, Fig. 2 a bogie according to the invention with a first arrangement of the traction motor in top view, Fig. 3 a bogie according to the invention with a second arrangement of the traction motor in a partially cut-away front view, Fig. 4 a drive motor of a drive train according to the invention in longitudinal section with a first embodiment of an integrated shift clutch, Fig. 5 a drive motor of a drive train according to the invention in longitudinal section with a second embodiment of an integrated shift clutch, Fig. 6 a drive motor of a drive train according to the invention in longitudinal section with a third embodiment of an integrated shift clutch, Fig. 7 a drive motor of a drive train according to the invention in longitudinal section with a first embodiment of an external cooling circuit of the cooling device, Fig. 8 a drive motor of a drive train according to the invention in longitudinal section with a second embodiment of an external cooling circuit of the cooling device and Fig. 9 a drive motor of a drive train according to the invention in longitudinal section with a third embodiment of an external cooling circuit of the cooling device are illustrated schematically.

[0032] According to Fig. Figure 1 comprises a rail vehicle 1, which is exemplified as a multiple unit train, comprising a plurality of coupled cars, wherein a number of intermediate cars 3 are arranged between two end cars 2. Each of the cars 2, 3 has a car body 4, which is supported on rails of a track (not shown) by means of bogies 5 designed as powered bogies, which have at least one drive train according to the invention, and / or by means of unpowered running bogies 6. Fig. As is standard practice, bogies 5 are identified by filled-in wheels and running bogies 6 by unfilled wheels. The rail vehicle can also be designed as a locomotive whose body rests exclusively on powered bogies.

[0033] To supply the drive train with electrical energy, a pantograph 7 is arranged in the roof area of ​​one end car 2. This pantograph electrically contacts an overhead line (not shown) of a railway power supply network to feed in energy. The overhead line can carry a single-phase alternating current, the voltage of which is transformed down by a transformer 8 and rectified by a grid-side rectifier 9 to feed a DC link 10. This DC link, in turn, supplies two load-side pulse inverters 11, which each convert the DC voltage into a three-phase AC voltage of variable frequency and amplitude. This AC voltage powers traction motors 12, specifically their stator windings 27 (see figure). Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9) of the respective drive trains. The function of the power converters 9, 11 in particular is controlled by a central control unit 13 of the drive system. If the overhead line of the railway power supply network carries direct current, the DC link 10 can be supplied directly, for example, possibly via a DC-DC converter.

[0034] According to Fig. 2 and Fig. 3 comprises a bogie 6, a bogie frame 14, the central crossbeam 15 of which and two lateral longitudinal beams 16 are arranged in an H-shape. The bogie 6 is rotatably connected about a vertical axis and sprung to the car body 4 of the end car 2 via the bogie frame 14. Two wheelsets 17 are rotatably mounted on the longitudinal beams 16 in two wheel bearings 18 each, each wheelset 17 comprising a wheelset axle 19 and two wheel discs 20 rigidly connected to it. Each of the wheelsets 17 is driven by a traction motor 21, each forming a drive train according to the invention. Fig. 2 The traction motor 21 is coupled to the driven wheelset 17 via a gearbox 22. The wheelset-mounted gearbox 22 is coupled to the semi-sprung traction motor 21 via a cardan coupling 23, such as a curved-tooth or multi-plate coupling, to compensate for movements. Fig. Figure 3, however, shows a drive train designed as a gearless direct drive, in which a motor shaft (not shown) is designed as a hollow cylinder and coaxially surrounds the wheelset axle 19. The traction motor 21 drives the wheelset 17 by means of a hollow cardan shaft coupling 23.

[0035] According to Fig. 4 to Fig. Figure 9 of the drive train for a rail vehicle 1 comprises a traction motor 21, which is designed as a permanent magnet synchronous machine. Due to its rotational symmetry about the axis 39 defined below, only the upper half of the motor is shown. The traction motor 21 has an active part with a stator 24 and a rotor 25 rotatably arranged within and relative to the stator. The stator 24 comprises a stator lamination stack 26 with an inserted stator winding 27, the winding heads of which protrude from the end face of the stator lamination stack 26. The rotor 25 comprises a rotor lamination stack 28 with inserted permanent magnets 29. Furthermore, the traction motor 21 has a motor housing 30 with a cylindrical housing shell 31 in which the stator 24 is fixed against rotation, and bearing shields 32A, 32B covering the end faces of the housing shell 31. A first, A-side bearing shield 32A is located on the drive or A-side of the machine.A second, B-side end shield 32B is located on the opposite non-drive or B-side of the machine. At least the rotor 25 is arranged in an interior space 33 located in the motor housing 30 and encapsulated from the environment U. The encapsulation surrounds an interior space 33 of the traction motor 21, which is protected from dirt, moisture, and foreign objects from the environment U. The stator 24 may also be arranged in the encapsulated interior space 33. The traction motor 21 has a motor shaft 35 rotatably mounted in the end shields 32A, 32B via rolling bearings 34. The rotor lamination stack 28 is fixedly mounted to a tubular rotor carrier 36, which is connected via rotor hubs 37 to freewheel bearings 38 located around the motor shaft 35. This allows the rotor 25 to be rotatably mounted on the motor shaft 35. The motor shaft 35 and rotor 25 are rotatable about a common axis 39.Furthermore, the drive motor 21 has a cooling device 40 for dissipating waste heat generated in the active part by means of coolants flowing through cooling channels.

[0036] The cooling unit 40 has (see also Fig. 7 to Fig. 9) An internal cooling circuit extending within the encapsulated interior 33, with first cooling channels 41 passing through the rotor 25, for conveying a cooling medium. The cooling medium can be conveyed by an integrated fan 42 that is rotationally fixed to the rotor 25. The first cooling channels 41 preferably extend axially through the rotor 25 in the region of its circumference. The cooling medium, for example, cooling air, is circulated in the internal cooling circuit by the integrated fan 42, which is located on the B-side or, not shown, on the A-side of the rotor 25. This cooling airflow supports the thermal decoupling of a coupling 43 described below, in particular from the energized stator 24, during operation of the synchronous machine, in which electrical heat losses occur in the stator winding 27 and losses in the stator lamination stack 26.An effective cooling device 40 enables the use of synchronous machines with a high number of poles, for example 6 or 8 poles, thereby increasing the power and torque density of the drive train according to the invention. The cooling device 40 also includes further cooling channels through the motor housing 30 and / or stator 24 for an external cooling circuit, which also cools a coolant from the internal cooling circuit. Variants of the external cooling circuit of the cooling device 40 are described below with reference to... Fig. 7 to Fig. 9 described.

[0037] According to Fig. 4 to Fig. 6 The drive train comprises a switchable clutch 43 arranged within the encapsulated interior 33 of the motor housing 30 for transmitting torque from the rotor 25 to the motor shaft 35. The clutch 43 is switchable between an open position and a closed position. Fig. 4 to Fig. The closed position is shown in Figure 6. In the open position, no torque can be transmitted between rotor 25 and motor shaft 35, while in the closed position, torque can be transmitted. Compared to the prior art, where the openable and closeable clutch disengagement point is located outside the traction motor or motor housing between the motor shaft and the wheelset axle, it is relocated to the encapsulated interior 33 of the motor housing 30 between rotor 25 and motor shaft 35. Integrating the clutch 43 into the encapsulated interior 33 saves installation space for the drive train. Additionally, a separate clutch housing is no longer required to protect the switchable clutch 43 from environmental influences, as the encapsulation seals the interior 33 against the ingress of dirt, detergents / water, water, snow, dust, etc.Reducing the installation space required for the traction motor 21 with switchable clutch 43 thus increases the power and torque density of the drive train according to the invention. In the illustrated embodiments, the clutch 43 is arranged axially between the rotor 25 and the B-side bearing shield 32B. However, another identical switching clutch can also be arranged between the rotor 25 and the A-side bearing shield 32A if this is necessary due to the torques to be transmitted and if sufficient installation space is available. The drive train according to the invention, with a switchable clutch 43 integrated into the traction motor 21, enables controlled decoupling of the rotor 25 from the rotating wheelset 17 and, optionally, from a gearbox (see Figure 1). Fig. 2 us Fig. 3) should this be necessary for operational reasons or in the event of a fault to prevent the unwanted generator operation of the synchronous machine.

[0038] According to Fig. 4 to Fig. 6. The clutch 43 comprises a first clutch disc 44, which is non-rotatably connected to the rotor 25, and a second clutch disc 45, which is non-rotatably connected to the motor shaft 25. The first clutch disc 44 and the second clutch disc 45 each have spur teeth 46 facing each other on their end faces. Depending on the embodiment, the first clutch disc 44 is axially displaceable relative to the second clutch disc 45, or the second clutch disc 45 is axially displaceable relative to the first clutch disc 44, such that the spur teeth 46 are disengaged in the open position of the clutch 43 and are engaged with each other in the closed position of the clutch 43 to transmit a torque.On the facing end faces of the first and second clutch discs 44, 45, radially extending tooth flanks are formed on an annular surface. These flanks can be positively engaged or disengaged by mutually sliding the first and second clutch discs 44, 45. Such a toothed coupling 43 can reliably transmit very high torques.

[0039] According to Fig. 4 to Fig. 6 The clutch 43 has a magnetic body 48, which can be magnetized by means of an excitation coil 47, for generating an axially acting magnetic force on the axially displaceable first or second clutch disc 44, 45, and a mechanical spring device 49 for generating an axially acting spring force on the axially displaceable first or second clutch disc 44, 45. To engage the clutch 43, an excitation current flowing through the excitation coil is applied via the control device 13 (see Figure 6). Fig. 2) switchable and switchable. If a defect occurs in the traction motor 21 or in one of the drive inverters 11 supplying it (see below) Fig. 1) If a fault is detected or a drive train is taken out of service by switching to partial load operation, the control unit 13 controls the supply of the excitation current in order to move the clutch 43 from the closed to the open state or vice versa by energizing the excitation coil 47 or by switching off the current. The axially acting magnetic force is generated by switching on the excitation current, which is preferably routed to the excitation coil 47 without slip rings. As this current flows through the excitation coil 47, it generates a magnetic field in the magnet body 48. Depending on the embodiment, this field is taken over by the second clutch disc or by an adjacent support disc 50, which is rotationally fixed to the motor shaft 35, in order to attract the respective axially displaceable clutch disc 44 or 45.The magnetic force overcomes an axially acting tensile or compressive force generated by the mechanical spring device 49 between the clutch discs 44, 45, which - depending on the design of the clutch - holds them in the closed or open position.

[0040] In a first embodiment, the axially displaceable first clutch disc 44 has according to Fig. 4 an internal radial toothing which engages with an external radial toothing on a rotor carrier 36 supporting the rotor 25. The spring assembly 49 has several tension springs 52 distributed on a pitch circle around the axis 39, the spring force of which displaces the axially displaceable first clutch disc 44 from the second clutch disc 45 (in the Fig. 4 to the left) so that the clutch 43 assumes its open state when the excitation current is switched off and its closed state when the excitation current is switched on due to the acting magnetic force. The radial toothing 51 ensures that the first clutch disc 44 is rotationally fixed to the rotor 25 via the rotor carrier 36 by means of the interlocking of external and internal teeth, and is axially displaceable both relative to the rotor 25 and to the second clutch disc 45. In this first embodiment, the clutch 43 closes as long as the excitation current is switched on, since the magnetic force pulls the axially displaceable first clutch disc 44 against the second clutch disc 45, overcoming the opposing tensile force of the tension springs 52.To open the clutch 43, the excitation current must be switched off so that, after the magnetic force ceases, the spring force of the spring assembly 49 pulls the first clutch disc 44 away from the second clutch disc 45 in order to disengage the spur gears 46. An advantage of this first embodiment is its reliability, since if the excitation current fails, the clutch 43 opens and unintended regenerative operation of the machine is prevented.

[0041] In a second and third embodiment, the axially displaceable second clutch disc 45 has according to Fig. 5 and Fig. 6 an internal radial toothing which engages with an external radial toothing on a support disc 50 fixedly connected to the motor shaft 35. In these embodiments, the radial toothing 51 ensures that the second clutch disc 45 is rotationally fixed to the motor shaft 35 via the support disc 50 by means of the interlocking of the external and internal teeth, and is axially displaceable both relative to the support disc 50 and relative to the first clutch disc 44.

[0042] In the second embodiment, the spring assembly 49 has according to Fig. 5. One or a package of bistable disc springs 53 with two stable tilting states, in which the spring force acts axially in opposite directions. In a first tilting state of the disc springs 53, the spring force presses the axially displaceable second clutch disc 45 against the first clutch disc 44, so that the clutch 43 assumes its closed state when the excitation current is switched off. By switching on the excitation current, the disc springs 53 tilt into a second tilting state due to the generated magnetic force. In this second tilting state, the spring force pulls the axially displaceable second clutch disc 45 away from the first clutch disc 44, whereby the clutch 43 then remains in the open state even when the excitation current is switched off again.To maintain the closed state of the clutch 43, the excitation coil 47 does not need to be energized in this second embodiment, thus preventing any heat losses in the coil winding 27 during torque transmission. A further advantage is that the clutch 43 can be opened by briefly building up the magnetic field and is then held securely open by the tilted disc springs 53 even when the magnetic field is absent. The clutch 43 can be manually reset to the closed state. Likewise, in the event of a power failure to the excitation coil 47, the closed clutch 43 can be manually released to its open state by means of an emergency release mechanism (not shown).

[0043] In a third embodiment, the spring assembly 49 has according to Fig. Six compression springs 54, distributed around a partial circle around the axis 39, are arranged. The spring force of these springs presses the axially displaceable second clutch disc 45 against the first clutch disc 44, so that the clutch 43 assumes its closed state when the excitation current is switched off and its open state due to the acting magnetic force when the excitation current is switched on. The compression springs 54 press the axially displaceable second clutch disc 45 against the first clutch disc 44, causing the clutch 43 to assume its closed state. The excitation coil 47 is not energized in this third embodiment, which is energetically advantageous. By energizing the excitation coil 47, the generated magnetic force pulls the second clutch disc 45 away from the first clutch disc 44 against the spring force, thus opening the clutch 43.The excitation current for closing the clutch 45 is switched off when the speeds of the clutch discs 44, 45 are synchronized or when the vehicle is stationary, in order to re-engage the face teeth 46.

[0044] According to Fig. 4 to Fig. 6 are on a circumference of the first clutch disc 44 according to Fig. 4 or on a circumference of the support disc 50 according to Fig. 5 and Fig. 6 fan blades 55 are arranged on each side. The fan blades 55 can be designed as axially and radially extending ribs and ensure a cooling airflow through air turbulence in the interior 33 in the area of ​​the coupling 43 and the adjacent bearing shield 32B. Furthermore, the magnet body 48 with excitation coil 47 is thermally coupled to the B-side bearing shield 32B. By attaching the excitation coil 47 with magnet body 48 to the bearing shield 32B, these coupling components are additionally cooled from the outside by the airflow under the floor during operation of the rail vehicle 1, so that the heat losses generated when the excitation coil 47 is energized can also be dissipated in this way.

[0045] The following will be based on Fig. 7 to Fig. Nine embodiments of external cooling circuits of the cooling device 40 are described, the second cooling channels 56 ( Fig. 7), third cooling channels 57 ( Fig. 8) and fourth cooling channels 58 ( Fig. 9) run separately from the encapsulated interior 33 of the motor housing 30, serving not only to dissipate waste heat from the stator 26 but also, in particular, to recool the cooling medium circulating in the internal cooling circuit within the encapsulated interior 33. These cooling channels 56, 57, 58 can extend through the housing shell 31 in the axial direction and / or circumferential direction and can also extend outside the motor housing 30 to form a closed cooling circuit. This contributes to increasing the power and torque density of the drive train according to the invention. Fig. 7 to Fig. Figure 9 shows the shift clutch 43 integrated into the interior 33 according to the invention and the support of the rotor 25 on the motor shaft 35 via freewheel bearing 38, which is not shown for the sake of clarity.

[0046] According to Fig. Figure 7 shows that the cooling device 40 has second cooling channels 56 for guiding cooling air as a coolant. The cooling air can be drawn through the second cooling channels 56 by means of self-ventilation by a fan wheel 59 rotating with the motor shaft 35 outside the encapsulated interior 33. Alternatively, the cooling air can be drawn through the second cooling channels 56 by means of forced ventilation by a fan (not shown) located outside the motor housing.

[0047] According to Fig. 8 and Fig. The cooling device 40 has third cooling channels 57 for conveying a first coolant as a coolant. The first coolant can be pumped through the third cooling channels 57 by means of a first coolant pump, which is located outside the engine housing 30 and is not shown. The third cooling channels 57 running in the housing jacket 31 form a water jacket cooling system.

[0048] According to Fig.Figure 9 of the cooling device 40 comprises fourth cooling channels 58 for conveying a second coolant and a canned tube 61 arranged in an annular gap 60 between the stator 24 and the rotor 25. Within the motor housing 30, the canned tube 61 separates the encapsulated interior 33, in which the rotor 25 is located, from an outer chamber 62, in which the stator 24 is located, in a coolant-tight manner. The second coolant can be pumped through the fourth cooling channels 58 by means of a second coolant pump (not shown) and flows from the inlets 63 of the fourth cooling channels 58 into the outer chamber 62. After flowing around / through the stator, it exits the outer chamber 62 through outlets of the third cooling channels (not shown). The second coolant can be formed from transformer oil, which, as it flows through the outer chamber 62, directly cools the stator 24 and also absorbs waste heat from the adjacent internal cooling circuit.Outside the motor housing 30, the second coolant is cooled again before the second coolant pump delivers it back into the external chamber 62. This particularly effective direct cooling enables the use of more powerful synchronous motors, which significantly increases the power and torque density of the drive train according to the invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 215 576 A1

[0004] EP 3 350 904 B1

[0005] EP 3 469 692 B1

[0006] DE 10 2021 208 388 A1

[0007] EP 4 227 185 A1

[0008]

Claims

[1] Powertrain for a railway vehicle (1) comprising - comprising a traction motor (21) designed as a permanent magnet excited synchronous machine - an active part with a stator (24) and a rotor (25), - a motor housing (30) with a cylindrical housing shell (31) in which the stator (24) is fixed in a rotationally fixed manner, and with bearing shields (32A, 32B) covering the end faces of the housing shell (31), - an interior space (33) arranged in the motor housing (30) and encapsulated against an environment (U), in which at least the rotor (25) is arranged, - a motor shaft (35) rotatably mounted in the bearing shields (32A, 32B), on which the rotor (25) is rotatably mounted via freewheel bearings (38), and - a cooling device (40) for dissipating waste heat generated in the active part by means of a coolant flowing through cooling channels (41, 56, 57, 58), and - a wheelset (17) of the rail vehicle (1) which is driven by the traction motor (21), characterized by - a coupling (43) arranged within the encapsulated interior (33) for transmitting a torque from the rotor (25) to the motor shaft (35), - wherein the clutch (43) is designed to be switchable between an open position in which no torque can be transmitted between rotor (25) and motor shaft (35) and a closed position in which torque can be transmitted. [2] Powertrain according to claim 1, - wherein the clutch (43) has a first clutch disc (44) which is non-rotatably connected to the rotor (25) and a second clutch disc (45) which is non-rotatably connected to the motor shaft (35), - wherein the first clutch disc (44) and the second clutch disc (45) each have end teeth (46) facing each other on their end faces, and - wherein the first clutch disc (44) is axially displaceable relative to the second clutch disc (45) or the second clutch disc (45) is axially displaceable relative to the first clutch disc (44) such that the face teeth (46) are disengaged in the open position of the clutch (43) and engaged in the closed position of the clutch (43) to transmit a torque. [3] Powertrain according to claim 2, - wherein the coupling (43) has a magnetic body (48) which can be magnetized by means of an excitation coil (47) for generating an axially acting magnetic force on the axially displaceable first or second coupling disc (44, 45) and a mechanical spring device (49) for generating an axially acting spring force on the axially displaceable first or second coupling disc (44, 45), - wherein, for switching the clutch (43), an excitation current flowing through the excitation coil (47) can be switched on and off via a control device (13). [4] Powertrain according to claim 3, - wherein the axially displaceable first clutch disc (44) has an inner radial toothing (51) which engages with an outer radial toothing (51) on a rotor carrier (36) supporting the rotor (25), - wherein the spring device (49) has at least one tension spring (52) whose spring force pulls the axially displaceable first clutch disc (44) away from the second clutch disc (45), so that the clutch (43) assumes its open state when the excitation current is switched off and its closed state when the excitation current is switched on due to the acting magnetic force. [5] Powertrain according to claim 3, - wherein the axially displaceable second clutch disc (45) has an inner radial toothing (51) which engages with an outer radial toothing (51) on a support disc (50) fixedly connected to the motor shaft (35), - wherein the spring device (49) has at least one bistable disc spring (53) with a first tilting state in which the spring force presses the axially displaceable second clutch disc (45) against the first clutch disc (44), so that the clutch (43) assumes its closed state when the excitation current is switched off, and with a second tilting state in which the disc spring (53) tilts when the excitation current is switched on and in which the spring force pulls the axially displaceable second clutch disc (45) away from the first clutch disc (44), so that the clutch (43) remains in the open state even when the excitation current is switched off again. [6] Powertrain according to claim 3, - wherein the axially displaceable second clutch disc (45) has an inner radial toothing (51) which engages with an outer radial toothing (51) on a support disc (50) fixedly connected to the motor shaft (35), - wherein the spring device (49) has at least one compression spring (54) whose spring force presses the axially displaceable second clutch disc (45) against the first clutch disc (44), so that the clutch (43) assumes its closed state when the excitation current is switched off and its open state when the excitation current is switched on due to the acting magnetic force. [7] Powertrain according to any of the preceding claims, - wherein the cooling device (40) has an internal cooling circuit extending within the encapsulated interior (33) with first cooling channels (41) passing through the rotor (25) for guiding a cooling medium, and - wherein the cooling medium can be conveyed by a self-contained fan (41) which is connected to the rotor (25) or the motor shaft (35) in a rotationally fixed manner. [8] Powertrain according to any of the preceding claims, - wherein fan blades (55) are arranged on a circumference of the first clutch disc (44) and / or the support disc (50). [9] Powertrain according to any one of claims 3 to 8, - wherein the magnetic body (48) with excitation coil (47) is thermally coupled to a bearing shield (32B). [10] Powertrain according to any one of the preceding claims, - wherein the cooling device (40) has second cooling channels (56) for guiding cooling air as a coolant, and - wherein cooling air can be conveyed through the second cooling channels (56) by means of a fan wheel (59) rotating with the motor shaft (35) and / or a fan arranged outside the motor housing (30). [11] Powertrain according to any one of the preceding claims, - wherein the cooling device (40) has third cooling channels (57) for guiding a first cooling fluid as a coolant, and - wherein the first coolant can be pumped through the third cooling channels (57) by means of a first coolant pump. [12] Powertrain according to any one of the preceding claims, - wherein the cooling device (40) has fourth cooling channels (58) for guiding a second cooling fluid as a coolant and a slotted tube (61) arranged in an annular gap (60) between stator (24) and rotor (25), - wherein in the motor housing (30) the canned tube (61) separates the encapsulated interior space (33), in which the rotor (25) is arranged, from an outer space (62), in which the stator (24) is arranged, in a coolant-tight manner, and - wherein the second coolant can be conveyed through the fourth cooling channels (58) by means of a second coolant pump and flows from the inlets (63) of the fourth cooling channels (58) into the outer space (62) and, after flowing around / through the stator (24), flows out of the outer space (62) through the outlets of the fourth cooling channels (58). [13] Powertrain according to any one of the preceding claims, - wherein the motor shaft (35) of the traction motor (21) is coupled to the driven wheelset (17) via a gearbox (22). [14] Powertrain according to claim 13, - wherein the motor shaft (35) is coupled to a gearbox input shaft of the gearbox (22) via a cardan coupling (23). [15] Powertrain according to any one of claims 1 to 12, - wherein the motor shaft (35) of the traction motor (12) is designed as a hollow cylinder and coaxially surrounds the wheelset shaft (19). [16] Bogie (5) for a rail vehicle (1), comprising - a powertrain according to any of the preceding claims, - Wheelset bearings (18) in which the driven wheelset (17) is rotatably mounted, - a bogie frame (14) which is resiliently supported on the axle bearings (18) and on which the traction motor (21) is at least partially supported. [17] Railway vehicle (1) comprising - a bogie (5) according to the preceding claim, and - a vehicle body (4) which is spring-loaded and supported on the bogie (6).

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