TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a ducting for a traction motor cooling system of a rail vehicle, as well as to the associated cooling system and rail vehicle.

BACKGROUND ART

[0002] A ducting for a traction motor cooling system of a rail vehicle is disclosed in CN201400171U. To meet the space requirement, the ducting comprises a common air inlet and multiple air outlets. The common air inlet is formed at a connecting part of the front end of a plurality of branch ducts; and an air outlet is respectively arranged at the tail end of each branch duct. Flow guide plates are arranged inside each branch duct for guiding the air and reducing flow resistance. The ducting arrangement is not optimised in terms of width. [0003] A traction motor cooling system of a rail vehicle is disclosed in CN104539103. The system comprises a cooling air unit and two main air ducts running in parallel at a distance from one another. The air inlets of the two main air ducts are connected each with one of the two air outlets of the cooling air unit, and the air outlets of the two main air ducts are communicated with air inlets of two traction motors of a vehicle body bogie, respectively. The main air ducts providing air for the two traction motors independent of each other and system resistance is reduced. Unbalanced air distribution is avoided and the cooling efficiency is improved. However, this system requires a substantial space in particular in the region in which the two main ducts run in parallel. SUMMARY OF THE INVENTION

[0004] The invention aims to provide a more compact ducting arrangement for a traction motor cooling system of a rail vehicle.

[0005] According to a first aspect of the invention, there is provided a ducting for a traction motor cooling system for a running gear of a rail vehicle, the running gear comprising a first wheel set, a second wheel set, a first traction motor for driving the first wheel set, a second traction motor for driving the second wheel set, the first traction motor being provided with a first cooling inlet, the second traction motor being provided with a second cooling inlet, the traction motor cooling system comprising a first fan outlet and a second fan outlet, the ducting comprising a first duct for connecting the first fan outlet with the first cooling inlet and a second duct for connecting the second fan outlet with the second cooling inlet, the first duct being provided with a first duct inlet and a first duct outlet, the second duct being provided with a second duct inlet and a second duct outlet, wherein the second duct has two parallel branches, a portion of the first duct being located between the two parallel branches.

[0006] This arrangement is particularly compact in terms of width and does reduce the pivoting angle of the running gear.

[0007] According to various embodiments:

The first duct is shorter than the second duct.

- The first duct outlet is located between the two parallel branches.

- The second duct comprises an inlet branch between the second duct inlet and the two parallel branches.

- The first duct inlet and the second duct inlet are spaced apart from one another.

- The first duct inlet and the second duct inlet are located in a common plane.

The first duct outlet the second duct outlet lie on a straig perpendicular to the common plane.

- The second duct comprises an outlet branch connected between the two parallel branches and the second duct outlet.

The first duct outlet the second duct outlet are in a common plane. [0008] The walls of the first duct and second duct can be made of sheet metal, e.g. stamped aluminium, plastics or of a composite material, e.g. glass reinforced plastics. According to an embodiment, the ducting comprises a one-piece cover comprising a first wall section forming a first inner wall surface of the first duct and a second inner wall surface of the second duct, the first inner wall surface and the second inner wall surface facing a common direction. The ducting may also comprise a partition wall common to the first duct and the second duct.

[0009] According to another aspect of the invention, there is provided a traction motor cooling system for a running gear of a rail vehicle, the running gear comprising a first wheel set, a second wheel set, a first traction motor for driving the first wheel set, a second traction motor for driving the second wheel set, the first traction motor being provided with a first cooling inlet, the second traction motor being provided with a second cooling inlet, the traction motor cooling system comprising:

- a fan unit comprising a first fan provided with a first fan outlet, a second fan provided with a second fan outlet, and

- a ducting as described hereinbefore, wherein the first duct inlet is connected to the first fan outlet and the second duct inlet is connected to the second fan outlet.

[0010] Preferably, the first fan has a first fan inlet, the second fan has a second fan inlet, the first and second fan inlets being separate. Thus, the two cooling circuits are pneumatically independent.

[0011] According to an embodiment, the fan unit comprises a single motor for driving the first fan and the second fan. The motor can be a through shaft motor placed between the first and second fans. [0012] According to another aspect of the invention, there is provided a rail vehicle comprising a running gear comprising a first wheel set, a second wheel set, a first traction motor for driving the first wheel set, a second traction motor for driving the second wheel set, the first traction motor being provided with a first cooling inlet, the second traction motor being provided with a second cooling inlet, wherein the rail vehicle comprises the traction motor cooling system as described hereinbefore, wherein the first duct outlet is connected to the first cooling inlet and the second duct outlet is connected to the second cooling inlet.

[0013] Preferably the first duct outlet is connected to the first cooling inlet by means of a first vertical flexible sleeve and the second duct outlet is connected to the second cooling inlet by means of a second vertical flexible sleeve. The vertical sleeves accommodate the movements between the running gear and the vehicle body of the rail vehicle.

[0014] According to various embodiments: - The first cooling inlet and the second cooling inlet are aligned on a longitudinal axis of the rail vehicle.

- The running gear is provided with two secondary suspension elements located on two lateral sides of the running gear in a median transverse vertical plane of the running gear, the first cooling inlet and the second cooling inlet being located on opposite sides of the median transverse vertical plane of the running gear.

- The ducting is fixed to an underframe of a vehicle body of the rail vehicle.

- The fan unit is fixed to an underframe of a vehicle body of the rail vehicle.

- The outlet branch is received in a channel element of an underframe of the rail vehicle.

BRIEF DESCRIPTION OF THE FIGURES

[0015] Other advantages and features of the invention will then become more clearly apparent from the following description of a specific embodiment of the invention given as non-restrictive examples only and represented in the accompanying drawings in which: - Figure 1 is an isometric view of a traction motor cooling system suspended to an underframe of a vehicle body of a rail vehicle, including a ducting of the cooling system;

- Figure 2 is an isometric view similar to the view of figure 1, but without the ducting;

- Figure 3 is an isometric view of the ducting and of parts of a fan unit of the cooling system of figure 1;

- Figure 4 is an isometric view of an upper part of the ducting of figure 3;

- Figure 5 is an isometric view of a lower part of the ducting of figure 3; - Figure 6 is a side view of the ducting of figure 3;

- Figure 7 is a top view of the ducting of figure 3;

- Figure 8 is a cross-section through line E-E of figure 7;

- Figure 9 is a cross-section through line D-D of figure 7;

- Figure 10 is a cross-section through line C-C of figure 7; - Figure 11 is a cross-section through line B-B of figure 7.

[0016] Corresponding reference numerals refer to the same or corresponding parts in each of the figures.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0017] With reference to figures 1 to 3, a running gear 10, more specifically a bogie, of a rail vehicle, comprises a H-shaped running gear frame 12 supported on a pair of front and rear wheel sets 14, 16 by means of a primary suspension 18, 20. The front wheel set 14 and the rear wheel set 16 are located respectively on a front side and a rear side of a median transverse vertical plane PI of the running gear 10. The running gear frame 12 is provided with a planar horizontal surface 22, 24 on each side of a median longitudinal vertical plane P2 of the running gear 10, in a region of connection of a transom 26 and of one of the longitudinal beams 28, 30 of the running gear frame 12, for supporting a secondary suspension unit (not shown). The running gear is provided with two traction units 32, 34 located on opposite sides of the median transverse vertical plane PI, each for powering one of the wheel sets 14, 16. Each wheel set 14, 16 is provided with a brake unit 36, 38.

[0018] In figures 1 and 2, only parts of an underframe of the vehicle body of the rail vehicle have been illustrated, in particular a T-shaped bolster subassembly 40 provided with a longitudinal channel member 42 that extends in the longitudinal direction of the vehicle from one end of the running gear towards the median transverse vertical plane PI of the running gear 10, on top of and at a distance from the running gear 10. A compressed air tank 44 is fixed to another part of the underframe at the opposite end of the running gear 10. A cooling unit 46 is also fixed to the underframe of the vehicle body farther away from the running gear 10. The compressed air tank is located between the running gear 10 and the cooling unit 46. The cooling unit 46 comprises a central trough-shaft motor 48, which drives two independent fans 50, 52, one at each end of the motor 48. Each fan 50, 52 has a fan inlet 54, 56 and a fan outlet 58, 60. The two fan outlets 58, 60 are located in a common vertical transverse plane and on each side of a median vertical longitudinal plane of the vehicle body, which is identical with the median vertical longitudinal plane P2 of the running gear in a nominal position of the rail vehicle.

[0019] Each traction unit 32, 34 is provided with a cooling inlet 62, 64 facing up and connected to a vertically extending flexible sleeve 66, 68 illustrated in Figure 2. One of the flexible sleeves 68 opens into an opening of the longitudinal channel member 42 of the bolster subassembly 40. The two cooling inlets 62, 64 are substantially aligned in the median longitudinal vertical plane P2 of the running gear 10.

[0020] A ducting 70, shown in figure 1 and left out in figures 2 and 3, is fixed to the underframe of the vehicle and comprises a first duct 72 for connecting the fan outlet 58 to the closest cooling inlet 62 and a second duct 74 for connecting the second fan outlet 60 to the farthest of the cooling inlets 64. The two ducts 72, 74 are pneumatically independent from one another. [0021] The first duct 72 comprises an inlet 76 connected to the fan outlet 58, an outlet 78 connected to the flexible sleeve 66 and the cooling inlet 62 and a single flow path between the inlet 76 and outlet 78. The second duct 74 comprises an inlet 80 connected to the second fan outlet 60 and a main inlet branch 82 which extends from the inlet 80 to a fork at which the second duct is divided in two parallel branches 84, 86 that pass on each side of a portion of the first duct 72 before rejoining downstream from the outlet 78 of the first duct 72 into a single outlet branch 88 that is received within the channel member 42 of the bolster subassembly 40, and with an outlet 90 connected to the flexible sleeve 68 and the second cooling inlet 64. The inlet 76 of the first duct 72 and the inlet 80 of the second duct 74 lie in a common vertical plane P3. The outlet 78 of the first duct 72 and the outlet 90 of the second duct lie in a common horizontal plane P4 and on straight line X, which is perpendicular to the plane P3 of the inlets 76, 80 and lies in a median vertical longitudinal plane of the vehicle body, which is identical with the median vertical longitudinal plane P2 of the running gear 10 in a nominal position of the rail vehicle. The portion of the first duct 72 located between the two parallel branches 84, 86 includes the outlet 78 of the first duct 72.

[0022] The ducting 70 is made of glass reinforced plastic plates that are moulded and bonded together. As shown in figures 6 to 11, the ducting comprises a cover 92, an inner lower part 94 and an outer lower part 96. In the cross-section of figure 8, the two lower parts 94, 96 are U-shaped and placed on top of one another. The base wall 97 of the upper part 96 constitutes a partition wall between the first duct 72 and the second duct 74 and has an upper face that forms an internal surface of the inlet branch 82 of the second duct 74 and a lower face that forms an internal surface of the first duct 72. In the cross-section of figure 9, the cover 92 is U-shaped, the outer lower part 96 is divided in two channel sections 98, 100 to form with the cover 92 the two parallel branches 84, 86 of the second duct 74. The inner lower part 94 is located below and between the two channel sections 98, 100 to form the first duct 72 with the walls of the two channel sections 98, 100 and of the cover 92. The cross- section of figure 10 is located downstream from the outlet 78 of the first duct 72 and shows the cover 92, which closes the two U-shaped channels 98, 100 to form the parallel branches 84, 86. [0023] The impellers of the two fans 50, 52 are driven by the same fan motor 48, thus the two impellers operate at the same rotation speed. The longer duct 74 is expected to have slightly more pressure losses. However, since the airflow rate varies as a function of the square root of the pressure, the airflow rate is substantially the same in the two ducts.

[0024] The arrangement of the air ducts 72, 74 is particularly space-efficient in the region of the brake unit 36 of the first wheel set 14 where the width of the ducting 70 has to be minimised to allow a pivoting movement of the running gear 10 about a vertical axis. The arrangement also takes advantage of the longitudinal channel 42 formed by the bolster subassembly 40. Thanks to this arrangement, it is possible to keep the cooling inlets 62, 64 of the first traction motor and of the second traction motor close to the median vertical longitudinal plane P2 of the running gear 10.

[0025] While the above example illustrates a preferred embodiment of the present invention, various other arrangements can also be considered. In particular, the general shape of the ducting will vary with the position and orientation of the cooling inlets 62, 64 and fan outlet 58, 60. The ducting 70 can be made of thin sheets of metal, plastic, or a composite material.