Self-venting engine, especially for a rail vehicle, rail vehicle with such an engine and assembly method for it

Description

[0001] The present invention relates to a self-ventilating motor, particularly for railway vehicles, and to a railway vehicle comprising such a motor. The invention also relates to a mounting method associated with such a self-ventilating motor.

[0002] In the field of railway vehicles, traction motors provide high power and tend to heat up. Cooling channels are provided in the motor casing, and an airflow, generated by a fan mounted directly on an output shaft of the motor, is pushed through these channels to cool the motor, which is thus called a self-ventilated motor.

[0003] However, such a self-ventilating motor has the drawback of being particularly noisy. Indeed, the airflow generated by the fan is turbulent and a significant source of noise.

[0004] To improve cooling efficiency, it is common practice to channel the airflow generated by the fan to the ducts through an air passage in a double-walled housing. The two walls create a passage between them for the airflow generated by the fan. Such a housing is a complex component, usually cast, which places stresses on its structure. For mechanical strength, internal ribs connecting the two walls are incorporated into the air passage. These ribs cause pressure losses and are a source of noise. For demolding the housing, the air passage has diverging draft angles at its ends, which also cause pressure losses and contribute to additional noise.

[0005] EP 3 819 148 describes a ventilated motor equipped with a cooling device comprising a motor-fan independent of the motor shaft.

[0006] FR-3 042 757-A1 describes, for example, a self-ventilating engine equipped with such a housing, the engine also being equipped with noise reduction accessories. However, these accessories are relatively bulky and their function is to reduce the noise generated by the propeller and the housing, without reducing the noise at its source.

[0007] It is these problems that the invention aims to address in particular, by proposing a self-ventilating engine that is quieter.

[0008] For this purpose, the invention relates to a self-ventilating engine, in particular for railway vehicles, according to claim 1.

[0009] According to the invention, the air passage has a passage cross-section which decreases as one moves from the air inlet to the air outlet.

[0010] Thanks to the invention, the air passage does not include any diverging sections that would generate pressure losses in the airflow circulating within it. The noise generated by the airflow in the air passage is thus reduced. Consequently, the self-ventilated motor according to the invention is quieter than self-ventilated motors of the prior art. The housing includes a diffuser, which partially obstructs the air outlet so as to channel the airflow circulating in the air passage into the channels.

[0011] The housing also includes straightening fins, which are arranged in the air passage upstream of the diffuser, the straightening fins being configured to direct the airflow circulating in the air passage parallel to the channels.

[0012] The diffuser includes orifices, each orifice being aligned with a corresponding channel, two adjacent orifices being separated by a wall, while the straightening fins are made in one piece with the diffuser, each wall being extended, within the air passage, by a respective straightening fin.

[0013] According to advantageous but not mandatory aspects of the invention, such a self-ventilating engine may incorporate one or more of the following features taken individually or in any technically permissible combination: The housing comprises: a flange, which is supported by the casing and forms a first surface creating an internal air passage surface; the flange and casing together forming a mounting subassembly; and a cover, which is separate from the flange, attached to the mounting subassembly, and forms a second surface. This second surface is located opposite the first surface when the cover is attached to the mounting subassembly and forms an external air passage surface, while the internal and external surfaces together define the air passage. The flange includes a flange for attaching it to the casing; the flange is formed around the periphery of the diffuser, while the cover is attached to the mounting subassembly via the flange. The flange is cast.The housing comprises: a flange, which is supported by the casing and which provides a first surface forming an internal surface of the air passage, the flange and the casing forming a mounting sub-assembly, and a cover, which provides a second surface located opposite the first surface, the internal and external surfaces together delimiting the air passage, while the flange and the cover are manufactured as a single piece by additive manufacturing.

[0014] The invention also relates to a railway vehicle, comprising a body and a self-ventilating engine as defined above.

[0015] According to another aspect, the invention also relates to a method for assembling a self-ventilating engine as defined above, the method comprising the following steps: a) assemble the flange to the casing, so as to form the mounting sub-assembly, then b) assemble the cover to the mounting sub-assembly, so as to form the air passage.

[0016] This process induces the same advantages as those mentioned in connection with the self-ventilating engine of the invention. The invention will be better understood, and other advantages thereof will become more apparent in light of the following description of an embodiment of a self-ventilating engine, a railway vehicle, and an assembly method, conforming to its principle, given solely by way of example and with reference to the accompanying drawings, in which: there figure 1 is a schematic representation of a railway vehicle according to the invention, comprising a self-ventilating engine also according to the invention; the figure 2 is a cut of the self-ventilating engine of the figure 1 ; there figure 3 is an exploded perspective view of a frame and crankcase of the self-ventilating engine of the figure 1 , and the figure 4 represents, on a larger scale, a detail of the frame and crankcase of the self-ventilating engine of the figure 2 , identified by a frame IV at the figure 2 .

[0017] A railway vehicle 10 is schematically represented on the figure 1 The rail vehicle 10, also referred to simply as "vehicle 10" hereafter, runs on rails 12 which are assumed here to be straight and horizontal. The vehicle 10 comprises a body 14, which provides an internal volume V14. The internal volume V14 is here a passenger compartment.

[0018] Carriage 14 rests on bogies. Only one bogie 16 is shown on the figure 1 This bogie 16 includes wheels 18, which run on rails 12. Some of the wheels 18 are driven by a motor 20, which is mounted on the bogie 16. The motor 20 is an electric motor, which is supplied with electrical energy by means of a power supply. The power supply is not shown.

[0019] We now describe engine 20 using the figures 2 à 4 .

[0020] The engine 20 comprises a casing 22, in which are housed engine components 24.

[0021] The motor components 24 comprise a stator 26 fixed to the frame 22 and a rotor 28 with a shaft 282. The shaft 282 is integral with the rotor 28 and is free to rotate relative to the frame 22 around a main axis X20. The main axis X20 is also a longitudinal axis of the motor 20.

[0022] The shaft 282 includes a front end 28A, here located on the left of the figure 2 , on which a ventilation fan 29 is mounted. Thus, when the shaft 282 is rotating, during normal engine operation, the fan 29 also rotates and generates an airflow that cools the engine 20, as explained later. The engine 20 is therefore a so-called "self-ventilating" engine, that is, one that generates its own cooling air without requiring an additional cooling device.

[0023] The frame 22 here includes a cradle 22A on which a drum 22B is mounted. On the figure 3 Only the cradle 22A is shown. The cradle 22A serves, among other things, to fix the motor 20 to the bogie 16, while the drum 22B forms a peripheral enclosure of the motor 20, which receives and protects the motorization components 24.

[0024] During operation, the motor 20 tends to heat up. The frame 22 has air circulation channels 30, which extend parallel to the main axis X20 and are designed to cool the motor 20 during operation. The channels 30 are therefore cooling channels for the motor 20, provided within the frame 22. In the illustrated example, the channels 30 extend through the cradle 22A and the drum 22B. The channels 30 are distributed around the main axis X20, with only two channels 30 visible in the cross-sectional view of the figure 2 .

[0025] Advantageously, the channels 30 each have a constant surface area, preferably a circular section, so as not to generate pressure loss when an airflow circulates in these channels 30, and thus limit the generation of noise in the channels 30.

[0026] The engine 20 also includes a crankcase 32, which is fixed to the frame 22 and in which a cavity forming an air passage 34 is provided. The air passage 34 opens from the crankcase 32 via an air outlet 36, which leads into the channels 30. The air passage 34 also includes an air inlet 38, which is connected to the air outlet 36 via the air passage 34. The air inlet 38 is positioned opposite the propeller 29 so as to receive most of the airflow generated by the rotating propeller 29. Thus, the airflow generated by the propeller 29 enters the air passage 34 through the air inlet 38, flows through the air passage 34, exits through the air outlet 36, and then passes into the channels 30.

[0027] In the example and advantageously, the air inlet 38 surrounds the propeller 29, radially to the main axis X20.

[0028] In the illustrated example, the housing 32 comprises a flange 40 and a cover 50, which are separate parts and are assembled together in such a way as to provide the passage of air 34 between them.

[0029] The flange 40 is supported by the frame 22 and comprises a first surface 42, which forms an internal surface 34A of the air passage 34. The flange 40 is advantageously manufactured by casting, as this manufacturing process is economical to implement. When the flange 40 is assembled to the frame 22, the flange 40 and the frame 22 together form a mounting subassembly 60.

[0030] The cover 50 is fixed to the mounting sub-assembly 60 and includes a second surface 52, which is located opposite the first surface 42 when the cover 40 is fixed to the mounting sub-assembly 60 and which forms an external surface 34B of the air passage 34. The cover 50 is advantageously manufactured by casting.

[0031] It is therefore understood that the air passage 34 is delimited by the first surface 42 and by the opposing second surface 52. The shapes of the first and second surfaces 42 and 52 can thus be chosen with greater freedom compared to the housings of the prior art, which were manufactured in a single piece by casting.

[0032] The first and second surfaces 42 and 52 are generally shaped like surfaces of revolution around the principal axis X20. The air passage 34 is therefore a volume of revolution around the principal axis X20. As one moves from the air inlet 38 to the air outlet 36, the first and second surfaces 42 and 52 move closer to each other, as illustrated in the diagrams. figures 2 And 4where the housing 32 is shown in cross-section. Thus, the air passage 34 has a cross-section that decreases as one moves from the air inlet 38 to the air outlet 36. Pressure losses in the air passage 34 are limited, resulting in a reduction of the noise generated by the motor 20 during operation.

[0033] We understand that the passage section reduces as we move from the air inlet 38 to the air outlet 36 in the sense that the air passage section 34 has an area whose value decreases in the direction of air circulation between the air inlet 38 and the air outlet 36.

[0034] Advantageously, the air passage 34 has a passage cross-section which decreases monotonically as one moves from the air inlet 38 to the air outlet 36. By monotonically, we mean that for any two points located between the air inlet 38 and the air outlet 36, with one of the two points being closer to the air outlet than the second point, the passage cross-section at the first point is strictly less than the passage cross-section at the second point.

[0035] The flange 40 advantageously includes a diffuser 44, which partially closes the air outlet 36 so as to channel the airflow circulating in the air passage 34 towards the channels 30. The transition between the air passage 34 and the channels 30 is thus gradual, which reduces turbulence of the airflow entering the channels 30, and therefore reduces noise generation.

[0036] In the illustrated example, the diffuser 44 includes orifices 46, each orifice 46 being aligned with a respective channel 30, two neighboring orifices 46 being separated by a wall 48. The wall 48 is profiled so that the air passage cross-section gradually decreases between the air passage 34 and each of the channels 30.

[0037] The flange 40 includes a flange 49, which is here formed on the periphery of the diffuser 44 and which serves to fix the flange 40 to the frame 22. The flange 40 is here assembled to the frame 22 by means of screws 100 represented by their center lines for some of them, which cooperate with first holes 49A formed in the flange 49.

[0038] In the illustrated example, each flange 49 comprises four sets of two first holes 49A, while a second hole 49B is also provided in the flange 49, between the first holes 49A of each set of two first holes. Only three sets of two first holes 49A are visible at the figure 3 , but the position of the fourth can be deduced from the fact that they are regularly distributed around the main axis X20. Alternatively, the number of sets of the first two holes 49A is different from four.

[0039] The second hole 49B is tapped here and serves for the assembly, by means of screws 102 represented by their center lines for some of them, of the cover 50 to the flange 40. In other words, when the flange 40 is fixed to the frame 22, forming the mounting sub-assembly 60, the cover 50 is fixed to the mounting sub-assembly 60 by means of the flange 49.

[0040] The crankcase 32, and by extension the engine 20, is thus assembled according to an assembly process comprising the following steps: a) assemble the flange 40 to the carcass 22, so as to form the mounting sub-assembly 60, then b) assemble the cover 50 to the mounting sub-assembly 60, so as to form the air passage 34.

[0041] During step a), the orifices 46 of the diffuser 44 are aligned with the corresponding channels 30 before securing the assembly of the flange 40 to the casing 22. During step b), the second surface 52 is arranged opposite the first surface 42, forming the air passage 34.

[0042] In the illustrated example, the first and second surfaces 42 and 52 are surfaces of revolution around the main axis A20. However, the airflow generated by the propeller 29 is vortex and circulates in the air passage 34 with an orthoradial component to the main axis A20.

[0043] In an alternative not shown, the housing 32 advantageously includes straightening fins, which are provided in projection on one and / or the other of the first surface 42 and the second surface 52, the straightening fins being configured to orient the airflow circulating in the air passage 34 parallel to the air channels 30. In other words, the straightening fins serve to suppress the orthoradial component of the airflow in the air passage 34.

[0044] In the illustrated example, the housing 32 is cast, which is economical but requires manufacturing the flange 40 and the cover 50 as two separate pieces. This has the advantage of freeing up access to the air passage 34, and thus allows the straightening fins to be made in one piece with the flange 40. The shape of the straightening fins can therefore be designed primarily according to noise reduction requirements. For example, the straightening fins of the engine according to the invention are curved. Preferably, the straightening fins are made in one piece with the diffuser 44, each wall 48 being extended, within the air passage 34, by a respective straightening fin. In other words, the straightening fins are formed as a projection on the first surface 42 during the manufacturing of the flange 40.

[0045] As an alternative not shown, the housing is made from a single piece, for example by additive manufacturing, also known as "3D printing." This manufacturing process is more expensive than casting but offers greater freedom in the shapes of the parts to be produced. It is thus possible to manufacture a housing in a single piece with an air passage whose cross-section decreases as one moves from the air intake to the air outlet.

[0046] The embodiments and variants mentioned above can be combined to generate new embodiments of the invention, provided that such combinations remain within the scope of the annexed claims.

Claims

1. Self-ventilated motor (20), especially for a rail vehicle (10), comprising: - a frame (22), which houses motor components (24) comprising a shaft (282) pivoting relative to the frame (22), and in which cooling channels (30) are provided, - a casing (32), which is attached to the frame (22), in which an air passage (34) is provided and which comprises: • an air outlet (36), which opens into the channels (30), • an air inlet (38), connected to the air outlet (36) by the air passage (34), - a ventilation propeller (29) configured to generate an air flux entering the air inlet (38) and circulating in the air passage (34), wherein the air passage (34) has a passage cross-sectional area decreasing from the air inlet (38) to the air outlet (36), characterised in that: - the ventilation propeller (29) is rotatably connected to the shaft (282), - the casing (32) comprises a diffuser (44), which partially seals the air outlet (36) so as to channel, in the channels (30), the air flux circulating in the air passage (34) and straightening fins made as a single piece with the diffuser (44) and arranged in the air passage (34) upstream of the diffuser (44), the straightening fins being configured to orient the air flux circulating in the air passage (34) in parallel to the channels (30), the diffuser (44) comprising ports (46), each port being aligned with a corresponding channel (30), two neighbouring ports being separated by a wall (48), each wall (48) extending, within the air passage (34), to a respective straightening fin.

2. Self-ventilated motor (20) according to claim 1, wherein: - the casing (32) comprises: • a flange (40), which is carried by the frame (22) and which provides a first surface (42) forming an inner surface (34A) of the air passage (34), the flange and the frame forming a mounting subassembly (60), and • a cover (50), which is distinct from the flange (40), which is attached to the mounting subassembly (60) and which provides a second surface (52), the second surface being located opposite the first surface (42) when the cover (50) is attached to the mounting subassembly (60) and which forms an outer surface (34B) of the air passage (34), - the inner surface (34A) and the outer surface (34B) together delimit the air passage (34).

3. Self-ventilated motor (20) according to claim 2, wherein: - the flange (40) comprises a clamp (49) for attaching the flange to the frame (22), the clamp being provided at the periphery of the diffuser (44), - the cover (50) is attached to the mounting subassembly (60) via the clamp.

4. Self-ventilated motor (20) according to any one of claims 2 or 3, wherein the flange (40) is manufactured by foundry.

5. Self-ventilated motor (20) according to claim 1, wherein: - the casing (32) comprises: • a flange (40), which is carried by the frame (22) and which provides a first surface (42) forming an inner surface of the air passage (34), the flange and the frame (22) forming a mounting subassembly, and • a cover (50), which provides a second surface (52) located opposite the first surface (42), the inner surface (34A) and the outer surface (34B) together delimiting the air passage (34), - the flange (40) and the cover (50) are manufactured as a single piece by additive manufacturing.

6. Railway vehicle (10), comprising a body (14) and a self-ventilated motor (20) according to any one of the preceding claims.

7. Method for assembling a self-ventilated motor (20) according to any one of claims 2 or 3, the method comprising the following steps of: a) assembling the flange (40) to the frame (22), so as to form the mounting subassembly (60), and then b) assembling the cover (50) to the mounting subassembly (60), so as to form the air passage (34).