Pump for cooling system of a power transformer

Abstract

Pump for cooling system of a power transformer The present invention relates to a pump for cooling system of a power transformer, the pump comprising a frame comprising a casing (56) and a flange (58A, 58B). The flange and the casing each have respectively an outer surface (78A, 78B) and an inner surface (80A, 80B), the inner surfaces being flush with each other. The pump comprises a centering device (74) of the flange relative to the casing, the centering device (74) comprising a diffuser (94) which comprises blades (98) extending radially to a centering surface (100) in contact with the casing and the flange. The flange and the carcass are in contact along a planar contact interface (88A, 88B), which extends from the centering surface (100) to one of the outer surfaces of the flange and the carcass. Figure for abstract: 2

Description

Title of the invention: Pump for a cooling system of a power transformer

[0001] The present invention relates to a pump for a cooling system of a power transformer, the pump comprising a frame, the frame comprising at least one casing and a flange, the flange being a suction flange or a discharge flange; the flange and the casing each having respectively an outer surface and an inner surface, the inner surfaces of the flange and the casing delimiting an interior volume of the pump and being flush with each other.

[0002] Such a pump has interface dimensions and in particular radial gauge dimensions to be respected according to a standard, for example the TS 50537-2 (2010) standard for traction transformer accessories and cooling systems. This radial gauge imposes a maximum size on the pump.

[0003] To have a pump with the highest possible hydraulic performance, it is necessary that the hydraulic active part of the pump occupies as much space as possible to the detriment of the structural parts. Indeed, each unit of volume of space used for the structure or mechanical strength, to the detriment of the fluid flow, reduces the overall performance expected from the pump.

[0004] When assembling the flange to the carcass, the two parts are positioned and brought together against each other and then fixed. However, such positioning must be implemented precisely and requires centering of these two parts.

[0005] To do this, in a conventional manner, the two parts have fixing collars and the centering is achieved by a male shoulder in the collar of one of the two parts (carcass or flange) and a complementary female shoulder in the collar of the other.

[0006] However, it is very complex to achieve centering by shoulder, sealing and then the passage of the fixing screws while respecting the maximum radial template constraint, and therefore the maximum external diameter constraint. For example, machining a shoulder of a few millimeters to allow centering results in an increase in the external radius of the part by these same few millimeters.

[0007] Since the maximum radial template constraint must be respected, this increase in thickness is to the detriment of the internal volume of the pump, and therefore to the detriment of the hydraulic performance of the pump.

[0008] In addition, the presence of these shoulders complicates the machining of the two parts.

[0009] Furthermore, it would also be advantageous if the pump remained lightweight, as the required from the point of view of the masses of transport systems are increasingly strict.

[0010] An aim of the invention is therefore to provide a solution making it possible to guarantee a centered assembly of the flange to the carcass while maintaining or increasing the hydraulic performance of the pump.

[0011] For this purpose, the invention relates to a pump of the aforementioned type characterized in that the pump further comprises a device for centering the flange relative to the casing, the centering device comprising a diffuser fixed to one of the flange and the casing, the diffuser comprising a base crown and blades, each blade extending radially relative to the base crown to a centering surface, the centering surface being in contact with the casing and the flange; and in that the flange and the casing are in contact along a contact interface, the contact interface extending from the centering surface to at least one of the outer surfaces of the flange and the casing, the contact interface being planar.

[0012] The pump according to the invention may comprise one or more of the following characteristics, taken in isolation or in any technically possible combination:

[0013] - the flange and the casing each have a fixing collar, the flange and the carcass being fixed relative to each other by a fixing system comprising at least one fixing member, each fixing member being respectively received in a passage passing through each fixing collar;

[0014] - the base crown is radially set back from the inner surfaces of the flange and the carcass, the radial distance separating the base crown from the inner surfaces being preferably greater than or equal to 5 mm, preferably greater than or equal to 10 mm;

[0015] - the pump further comprises an impeller and a motor received in the volume interior, the impeller being capable of circulating an internal cooling fluid, the impeller comprising a rotation shaft extending along a main pump axis and being connected to the motor, the motor being capable of exerting a torque on the rotation shaft to rotate the rotation shaft;

[0016] - the diffuser is configured to redirect the flow of a fluid leaving the impeller so that it flows parallel to the main pump axis;

[0017] - each blade has two lateral fluid redirection surfaces, each side redirection surface extending radially from the base crown to the centering surface of the blade, each side redirection surface having a curved shape which is tangent downstream to the main pump axis;

[0018] - for at least one of the blades, the two lateral redirection surfaces of the blade are parallel; and / or in which, for at least one of the blades, the two lateral redirection surfaces of the blade diverge from upstream to downstream;

[0019] - the maximum radial length of the contact interface (88A, 88B) is less than or equal to 60 mm, preferably less than or equal to 45 mm, advantageously less than or equal to 30 mm;

[0020] - at least two of the blades have different shapes;

[0021] - the diffuser is fixed to one of the flange and the carcass by hooping;

[0022] - said flange is a suction flange, the frame further comprising a flange of discharge extending opposite the suction flange, the suction flange being arranged upstream of the discharge flange; and

[0023] - the pump is an axial pump.

[0024] The invention also relates to a cooling system for a power transformer comprising:

[0025] - a cooling circuit in which an internal cooling fluid circulates power transformer, the internal cooling fluid being circulated by a pump as described above; and

[0026] - a heat exchanger for the heat transported by the internal cooling fluid dissement.

[0027] The invention further relates to a railway vehicle comprising a power transformer and a cooling system as described above, the power transformer preferably being capable of generating at output a voltage and current system having a voltage greater than or equal to 1 kV.

[0028] The invention also relates to a method of assembling a pump for a cooling system of a power transformer, the method comprising the following steps:

[0029] - providing a flange and a carcass, the flange being provided away from the carcass, the flange being a suction flange or a discharge flange, the flange and the carcass each having an outer surface and an inner surface respectively;

[0030] - provision of a centering device comprising a diffuser, the diffuser being provided away from the flange and the carcass, the diffuser comprising a base ring and blades, each blade extending radially from the base ring to a centering surface;

[0031] - fixing the diffuser to one of the carcass and the flange, such that each centering surface is in contact with said one of the carcass and the flange) and protrudes from it;

[0032] - assembly of the carcass and the flange, the flange being centered relative to the casing by the diffuser, the assembly being such that each centering surface is also in contact with the other of the casing and the flange; that the interior surfaces of the flange and the casing delimit an interior volume of the pump and are flush with each other; and that the flange and the casing are in contact along a contact interface, the contact interface being planar and extending from each centering surface to at least one of the outer surfaces of the flange and the carcass.

[0033] The invention will be better understood on reading the following description, given solely by way of example, and made with reference to the appended drawings, in which:

[0034] [Fig-1] [Fig.l] is a schematic view of an example of a railway vehicle according to an embodiment of the invention; and

[0035] [Fig.2] [Fig.2] is a schematic axial sectional view of an example of a pump of the railway vehicle of [Fig.l].

[0036] An example of a railway vehicle 10 is schematically illustrated in [Fig.l].

[0037] The railway vehicle 10 comprises at least one car, for example a plurality of cars.

[0038] The railway vehicle 10 comprises at least one power transformer 12 and a cooling system 14 comprising the power transformer 12.

[0039] The power transformer 12 is arranged in one of the cars of the railway vehicle 10.

[0040] To the extent that the power transformer 12 is here included in the railway vehicle 10, the power transformer 12 is therefore mobile over time relative to the ground.

[0041] The power transformer 12 is capable of transforming an input current, the input current being delivered by an alternating electrical energy source.

[0042] More precisely, the power transformer 12 is capable of modifying values ​​of a voltage and current system of the input current, into a voltage and current system of different values ​​at the output, but of the same frequency and preferably of the same shape.

[0043] For example, the power transformer 12 is capable of generating at output a voltage and current system having a voltage greater than or equal to 1 kV.

[0044] The power transformer 12 comprises at least two windings 16 around a core 18.

[0045] For the sake of simplicity, only one winding 16 is shown in [Fig.l].

[0046] The two windings 16 are magnetically coupled.

[0047] The two windings 16 are for example a primary winding and a secondary winding.

[0048] Different winding architectures 16 are known to those skilled in the art and will not be described in more detail here.

[0049] The power transformer 12 preferably comprises an electrical insulator 20 of the windings 16.

[0050] The insulator 20 is for example formed by a layer of varnish coating the bearings 16. Other insulators 20 are known to those skilled in the art and will not be described in more detail here.

[0051] The cooling system 14 is capable of maintaining the temperatures of the windings 16 and the insulation 20 at acceptable predetermined levels.

[0052] The choice of the dimensioning of the cooling system 14 is made in particular according to parameters, such as the losses to be evacuated, the external ambient temperature, noise constraints, dimensional constraints, mass constraints limiting the size of the transformer, and / or cost constraints.

[0053] The cooling system 14 comprises a cooling circuit 24 in which an internal cooling fluid 26 of the power transformer 12 circulates, and a heat exchanger 28 for the heat transported by the internal cooling fluid 26.

[0054] The cooling circuit 24 is closed.

[0055] The cooling circuit 24 comprises an enclosure 30 for receiving the trans power trainer 12, a circulation conduit 32 for the internal cooling fluid 26 and at least one pump 34 suitable for circulating the internal cooling fluid 26.

[0056] The circulation mode of the internal cooling fluid 26 is therefore forced.

[0057] Inside the enclosure 30, the power transformer 12 is immersed in the internal cooling fluid 26.

[0058] Preferably, channels allowing the circulation of the internal cooling fluid 26 are arranged in the core 18 and the windings 16 of the transformer, in order to allow the evacuation of heat from the core 18 and the windings 16 towards the internal cooling fluid 26.

[0059] The internal cooling fluid 26 is any type of gas or liquid that may be suitable.

[0060] A person skilled in the art is, in a known manner, able to determine the appropriate internal fluid for cooling the power transformer 12.

[0061] Preferably, for the above preferred power range, the cooling fluid is a liquid, preferably a transformer dielectric oil. As examples, the liquid comprises mineral oil or ester oil.

[0062] The heat exchanger 28 is capable of evacuating by convection the heat transported by the internal cooling fluid 26, via an external cooling fluid.

[0063] The terms “internal” and “external” are therefore to be understood here in relation to the circulation conduit 32.

[0064] The external cooling fluid is, for example, air or water. Alternatively, the external cooling fluid is any other fluid.

[0065] Preferably, the heat exchanger 28 comprises at least one forced convection system not shown. The mode of circulation of the external cooling fluid is then forced by the forced convection system which is in operation and imposes the circulation of the fluid.

[0066] The forced convection system is for example a fan.

[0067] Alternatively, the mode of circulation of the external cooling fluid is natural, that is to say not forced. The heat exchanger 28 is then without a forced convection system, or the forced convection system is present but is not put into operation over all the operating ranges of the transformer 10.

[0068] The heat exchanger 28 comprises, for example, a box 36 in which the external cooling fluid circulates.

[0069] From upstream to downstream, the circulation conduit 32 comprises an inlet 38 connected to the enclosure 30, an upstream section 40 from the enclosure 30 to the heat exchanger 28, a cooling section 42 passing through the heat exchanger 28, a downstream section 44 from the exchanger 28 to the enclosure 30 and an outlet 46 connected to the enclosure 30.

[0070] Here and hereinafter, the terms “upstream” and “downstream” will be understood in relation to the direction of circulation of the internal cooling fluid 26.

[0071] The direction from upstream to downstream is represented in [Fig.l] by arrow 48.

[0072] The circulation conduit 32 is thermally conductive.

[0073] In the example illustrated, the cooling section 42 passes through the box 36 of the heat exchanger 28. The external cooling fluid is in contact with the cooling section 42 of the circulation duct 32.

[0074] In the example of [Fig.l], the cooling section 42 has laces.

[0075] In other words, the cooling section 42 is zigzag.

[0076] In the example of [Fig.l], the cooling circuit 24 comprises a single pump 34.

[0077] The pump 34 is for example arranged between the enclosure 30 and the heat exchanger 28.

[0078] In the example of [Fig.l], the pump 34 is here arranged downstream of the heat exchanger 28, in particular at the level of the downstream section 44 of the circulation duct 32. Alternatively, the pump 34 is arranged upstream of the heat exchanger 28, in particular at the level of the upstream section 40 of the circulation duct 32.

[0079] In an example not illustrated, the pump 34 forms the inlet 38 or the outlet 46 of the circulation conduit 32.

[0080] The pump 34 will now be described in more detail with reference to [Fig.2].

[0081] The pump 34 is capable of providing pressure and flow to the internal cooling fluid. dissement 26 in the circulation duct 32.

[0082] Pump 34 is a centrifugal pump.

[0083] The pump 34 comprises an impeller 50 and a motor 52.

[0084] In addition, the pump 34 comprises a frame 54, the frame 54 comprising at least a 56 carcass and a 58A suction flange.

[0085] The impeller 50 is suitable for circulating the internal cooling fluid 26.

[0086] The impeller 50 forms a moving element of the pump 34.

[0087] The impeller 50 comprises a rotation shaft 60 connected to the motor 52.

[0088] The impeller 50 also comprises a base body 62 and blades 64 extending to from the basic body 62.

[0089] The rotation shaft 60 extends along a main pump axis X.

[0090] The motor 52 is capable of exerting a torque on the rotation shaft 60 to rotate the shaft 60, the rotation being along the main pump axis X. For this, the motor 52 thus comprises a stator and a rotor, the rotor being integral with the rotation shaft 60.

[0091] The base body 62 of the impeller 50 is engaged with the rotation shaft 60, for example by means of a key, so as to have a joint rotation with the rotation shaft 60.

[0092] The base body 62 of the impeller 50 has a bottom 66 and a side wall 68.

[0093] The bottom 66 of the base body 62 is for example crossed by the rotation shaft 60.

[0094] The side wall 68 has a substantially cylindrical shape of revolution centered on the main pump axis X.

[0095] The blades 64 of the impeller 50 extend respectively from the bottom 66 and are surrounded by the side wall 68 of the base body 62.

[0096] The blades 64 are radially set back from the side wall 68.

[0097] As indicated above, the frame 54 includes the suction flange 58A and the carcass 56.

[0098] The chassis 54 also comprises a device 74 for centering the suction flange 58A relative to the carcass 56.

[0099] Further, the frame 54 includes a discharge flange 58B.

[0100] The frame 54 forms a fixed element of the pump 34, as opposed to the mobile element formed by the impeller 50. The impeller 50 is thus mobile in rotation relative to the frame 54.

[0101] The suction flange 58A is configured to hold the pump 34 on a structure of the cooling circuit 24, the structure being for example the enclosure 30 or the circulation conduit 32. The suction flange 58A also provides a function sealing between the pump 34 and said structure 30, 32.

[0102] The suction flange 58A is in fluid communication with the structure 30, 32 on which it holds the pump 34.

[0103] The internal cooling fluid 26 enters the pump 34 via the suction flange 58A.

[0104] The suction flange 58A is configured to direct the internal cooling fluid 26, from the enclosure 30 or the circulation conduit 32, towards the impeller 50.

[0105] The suction flange 58A is centered on the main pump axis X.

[0106] The suction flange 58A is for example of revolution around the main axis of X pump.

[0107] The suction flange 58A is a single piece and for example made of aluminum or aluminum alloy.

[0108] The frame 56 is configured to support the stator of the motor 52.

[0109] In particular, the stator of the motor 52 is fixed to the frame 56.

[0110] The carcass 56 is in one piece, and for example made of aluminum or aluminum alloy.

[0111] The suction flange 58A and the carcass 56 each have respectively an outer surface 78A, 78B and an inner surface 80A, 80B.

[0112] The inner surfaces 80A, 80B of the suction flange 58A and of the carcass 56 delimit an inner volume 82 of the pump 34.

[0113] The internal cooling fluid 26 is contained in the interior volume 82.

[0114] The impeller 50 and the motor 52 are received in the interior volume 82 of the pump 34.

[0115] As illustrated in [Fig.2], the inner surfaces 80A, 80B of the suction flange 58A and the carcass 56 are flush with each other.

[0116] In other words, the inner surfaces 80A, 80B of the suction flange 58A and the carcass 56 are level and do not form a step at their joint.

[0117] The suction flange 58A and the carcass 56 are fixed relative to each other by a fixing system 84A comprising at least one fixing member, and preferably a plurality of fixing members.

[0118] For this, the suction flange 58A and the carcass 56 each have a fixing collar 86A, 86B respectively.

[0119] Each fixing collar 86A, 86B projects radially outwards. Here and hereinafter, the term “radial” is to be understood relative to the main pump axis X.

[0120] In one embodiment, each fixing collar 86A, 86B extends around the entire circumference of the suction flange 58A and the carcass 56. Alternatively, at least one of the collars is interrupted.

[0121] Each fixing member is respectively received in a passage passing through each fixing collar 86A, 86B. Each passing through is for example threaded.

[0122] Each fixing member thus passes through the fixing collar 86A of the suction flange 58A and the fixing collar 86B of the carcass 56.

[0123] Each fixing member is for example a screw or a bolt.

[0124] As illustrated in [Fig.2], the suction flange 58A and the carcass 56 are in contact along an upstream contact interface 88A.

[0125] The upstream contact interface 88A is defined as the contact surface between the suction flange 58A and the carcass 56.

[0126] The upstream contact interface 88A extends from at least one of the inner surfaces 80A, 80B to at least one of the outer surfaces 78A, 78B of the suction flange 58A and the carcass 56.

[0127] The upstream contact interface 88A runs along the fixing collars 86A, 86B of the suction flange 58A and of the carcass 56.

[0128] The upstream contact interface 88A is planar.

[0129] The upstream contact interface 88A extends in a plane perpendicular to the axis main pump X.

[0130] In other words, the upstream contact interface 88A is devoid of a shoulder.

[0131] The maximum radial length of the upstream contact interface 88A is less than or equal to 60 mm, preferably less than or equal to 45 mm, advantageously less than or equal to 30 mm.

[0132] The maximum radial length is defined as the radial length between the two extreme points of contact between the suction flange 58A and the carcass 56.

[0133] In the example of [Fig.2], the upstream contact interface 88A is discontinuous to ensure sealing between the suction flange 58A and the carcass 56.

[0134] In particular, one of the suction flange 58A and the carcass 56 delimits a seal surface 90A receiving a sealing gasket 92A, the seal surface 90A being closed by the other of the suction flange 58A and the carcass 56.

[0135] In the present case, the joint surface 90A is for example a groove.

[0136] In the example of [Fig.2], the seal surface 90A is delimited by the carcass 56. Alternatively, the seal surface 90A can be delimited by the suction flange 58A or delimited by both the carcass 56 and the suction flange 58A.

[0137] The seal 92A is for example a flat seal or an O-ring.

[0138] The seal 92A is for example made of an elastomer.

[0139] Even if the upstream contact interface 88A between the suction flange 58A and the carcass 56 is flat and perpendicular to the main pump axis X, said centering device 74 of the suction flange 58A relative to the carcass 56 according to the invention makes it possible to ensure this centering during assembly of the pump 34.

[0140] The centering device 74 comprises a diffuser 94 attached to one of the suction flange 58A and the carcass 56.

[0141] Preferably, the diffuser 94 is fixed in this way by hooping onto one of the suction flange 58A and the carcass 56. This is then a fixing with negative play, that is to say that the diffuser 94 is clamped by the part in which it is centered.

[0142] Alternatively, the diffuser 94 is fixed by any other means conceivable by those skilled in the art, for example by screwing members passing through the carcass 56 and the diffuser 94.

[0143] In the invention, the diffuser 94 thus performs a dual role: a first role of centering the suction flange 58A relative to the carcass 56, and a second role of guiding the flow of the fluid 26 in the pump 34.

[0144] The diffuser 94 is configured to redirect the flow of the fluid 26 at the outlet of the impeller 50. At the outlet of the impeller 50, the fluid has an ortho-radial direction and the diffuser 94 is configured to redirect the fluid so that it flows parallel to the main pump axis X.

[0145] The diffuser 94 is a single-piece, and for example made of aluminum or aluminum alloy.

[0146] At the diffuser 94, each of the inner surfaces 80A, 80B of the suction flange 58A and of the casing 56 has a circular cross-section. The cross-section is taken perpendicular to the main pump axis X.

[0147] The diffuser 94 comprises a base crown 96 and a plurality of blades 98.

[0148] The base crown 96 has a substantially cylindrical shape of revolution. centered on the main pump axis X.

[0149] The base crown 96 is radially recessed relative to the inner surfaces 80A, 80B of the suction flange 58A and the carcass 56.

[0150] The radial distance separating the base crown 96 from the interior surfaces 80A, 80B is for example greater than or equal to 5 mm, preferably greater than or equal to 10 mm.

[0151] The base crown 96 has a central opening crossed by the rotation shaft 60 of the paddle wheel 50.

[0152] A rotational guidance system allows rotation of the rotation shaft 60 relative to the base ring 96, the rotational guidance system being carried by the base ring 96 or the rotation shaft 60.

[0153] The rotational guidance system is for example a ball bearing system, a roller bearing system, or plain bearings.

[0154] The diffuser 94 advantageously comprises a number of blades 98 greater than or equal to 3.

[0155] At least two of the blades 98, advantageously at least three of the blades 98, respectively extend radially projecting from the base crown 96 to a centering surface 100, the centering surface 100 of the blade 98 being in contact with the carcass 56 and the suction flange 58A.

[0156] For example, at least one of the blades 98 does not reach the inner surface 80B of the carcass 56 and / or the inner surface 80A of the suction flange 58A.

[0157] The upstream contact interface 88A between the suction flange 58A and the carcass 56 thus extends from the centering surface 100 to one of the outer surfaces 78A, 78B of the suction flange 58A and the carcass 56.

[0158] In projection on a plane perpendicular to the main pump axis X, the blades 98 are arranged apart from each other.

[0159] The blades 98 are arranged at predetermined intervals along the circumference of the base ring 96.

[0160] The distribution of the blades 98 preferably has at least one rotational symmetry relative to the main pump axis X.

[0161] The blades 98 are arranged so as to redirect the fluid leaving the impeller 50 so that it flows parallel to the main pump axis X.

[0162] Each blade 98 has two fluid redirection side surfaces, each redirection side surface extending radially from the base ring 96 to the centering surface 100 of the blade.

[0163] Between two adjacent lateral redirection surfaces, the diffuser 94 delimits a circulation passage for the internal cooling fluid 26.

[0164] Said circulation passage is thus delimited laterally by the two adjacent lateral redirection surfaces, and is also delimited radially by the base crown 96 and the interior surfaces 80A, 80B of the suction flange 58A and of the carcass 56.

[0165] By “two adjacent redirection lateral surfaces” is meant two lateral surfaces of two distinct blades 98 for which no blade 98 is interposed circumferentially between them.

[0166] Each lateral redirection surface preferably has a curved shape, which is tangent downstream to the main pump axis X.

[0167] In other words, the lateral redirection surfaces of each blade 98 respectively have straight downstream regions parallel to the main pump axis X.

[0168] Alternatively, each lateral redirection surface has, for example, a straight shape, the blades 98 then having an arrow shape with a point oriented upstream.

[0169] For example, the blades 98 have identical shapes. Alternatively, at least two of the blades 98 have different shapes.

[0170] The discharge flange 58B is arranged downstream of the suction flange 58A.

[0171] The discharge flange 58B also has an outer surface 78C and a surface interior 80C. The interior surface 80C of the discharge flange 58B delimits said interior volume 82 of the pump 34, in which the internal cooling fluid 26 is contained.

[0172] The discharge flange 58B is configured to hold the pump 34 on a structure of the cooling circuit 24, the structure being for example the enclosure 30 or the circulation conduit 32. The discharge flange 58B also provides a sealing function between the pump 34 and said structure 30, 32.

[0173] The discharge flange 58B is in fluid communication with the structure 30, 32 on which it holds the pump 34.

[0174] The internal cooling fluid 26 exits the pump 34 via the discharge flange 58B.

[0175] The discharge flange 58B is configured to direct the internal cooling fluid 26, downstream of the impeller 50, towards the enclosure 30 or the circulation conduit 32.

[0176] In the example of [Fig.2], the pump 34 is an axial pump.

[0177] The discharge flange 58B is in particular aligned with the suction flange 58A along the main pump axis X.

[0178] The discharge flange 58B is centered on the main pump axis X.

[0179] In other words, the discharge flange 58B extends opposite the flange 58A suction.

[0180] The discharge flange 58B is for example of revolution around the main pump axis X.

[0181] The discharge flange 58B is a single-piece, and for example made of aluminum or aluminum alloy.

[0182] The discharge flange 58B and the carcass 56 are fixed relative to each other by a fixing system 84B comprising at least one fixing member, and preferably a plurality of fixing members.

[0183] For this, the discharge flange 58B has a fixing collar 86C, the carcass 56 having another downstream fixing collar 86D.

[0184] Each fixing collar 86C, 86D projects radially outward.

[0185] Each fixing member is respectively received in a passage passing through each fixing collar 86C, 86D. Each passing through is for example threaded.

[0186] Each fixing member thus passes through the fixing collar 86C of the discharge flange 58B and the downstream fixing collar 86D of the carcass 56.

[0187] Each fixing member is for example a screw or a bolt.

[0188] As illustrated in [Fig.2], the discharge flange 58B and the carcass 56 are in contact along a downstream contact interface 88B.

[0189] The downstream contact interface 88B is defined as the contact surface between the discharge flange 58B and the carcass 56.

[0190] The downstream contact interface 88B extends from at least one of the inner surfaces 80C, 80B to at least one of the outer surfaces 78C, 78B of the discharge flange 58B and the carcass 56.

[0191] The downstream contact interface 88B runs along the fixing collar 86C of the discharge flange 58B and the downstream fixing collar 86D of the carcass 56.

[0192] The downstream contact interface 88B is planar.

[0193] The downstream contact interface 88B extends in a plane perpendicular to the axis main pump X.

[0194] In other words, the downstream contact interface 88B is devoid of a shoulder.

[0195] The maximum radial length of the downstream contact interface 88B is less than or equal to 60 mm, preferably less than or equal to 45 mm, advantageously less than or equal to 30 mm.

[0196] The maximum radial length is defined as the radial length between the two extreme points of contact between the discharge flange 58B and the carcass 56.

[0197] In the example of [Fig.2], the downstream contact interface 88B is discontinuous to ensure sealing between the discharge flange 58B and the carcass 56.

[0198] In particular, one of the discharge flange 58B and the carcass 56 delimits a seal surface 90B receiving a sealing gasket 92B, the seal surface 90B being closed by the other of the discharge flange 58B and the carcass 56.

[0199] In the present case, the joint surface 90B is for example a groove.

[0200] In the example of [Fig.2], the seal surface 90B is delimited by the carcass 56. Alternatively, the seal surface 90B may be delimited by the discharge flange 58B or may be delimited by both the discharge flange 58B and the carcass 56.

[0201] The seal 92B is for example a flat seal or an O-ring.

[0202] The seal 92B is for example made of an elastomer.

[0203] A method of assembling the pump 34 as described above will now be described.

[0204] The assembly method includes providing the suction flange 58A and the carcass 56, the suction flange 58A being provided spaced from the carcass 56.

[0205] The method includes providing the centering device 74 includes the diffuser 94, the diffuser 94 being provided spaced from the suction flange 58A and the casing 56.

[0206] The method comprises securing the diffuser 94 in one of the casing 56 and the suction flange 58A, such that each centering surface 100 contacts and projects beyond said one of the casing 56 and the suction flange 58A.

[0207] The blades 98 thus have a free portion projecting along the main pump axis X and subsequently serving as a centering means.

[0208] The diffuser 94 is for example fixed by hooping.

[0209] The method then comprises assembling the carcass 56 and the suction flange 58A.

[0210] During assembly, the suction flange 58A is centered relative to the carcass 56 by the diffuser 94.

[0211] The assembly is such that each centering surface 100 is also in contact with the other of the casing 56 and the suction flange 58A; that the inner surfaces 80A, 80B of the suction flange 58A and the casing 56 delimit the inner volume 82 of the pump 34 and are flush with each other; and that the suction flange 58A and the casing 56 are in contact along an upstream contact interface 88A, the upstream contact interface 88A being planar and extending from each centering surface 100 to at least one of the outer surfaces of the suction flange 58A and the casing 56.

[0212] The suction flange 58A and the carcass 56 are then fixed to each other.

[0213] This fixing is implemented for example by means of the fixing system 84A above.

[0214] The embodiment described above corresponds to the centering of the suction flange 58A relative to the carcass 56, in a non-detailed variant, the discharge flange 58B is centered relative to the carcass 56 independently and in a similar manner to what has been described above.

[0215] The discharge flange 58B is then centered relative to the carcass 56 by another dedicated part.

[0216] Said other dedicated part is for example a diffuser or a support for a rotational guide element.

[0217] In the case where said other part is a diffuser, the description given above for the suction flange 58A and the diffuser 94 applies to the discharge flange 58B and to this other dedicated part.

[0218] Alternatively, the pump 34 is not an axial pump.

[0219] The pump 34 is for example a radial pump, the discharge flange 58B being centered on an axis perpendicular to the main pump axis X.

[0220] The discharge flange 58B is then, for example, arranged on the same side of the carcass 56 as the suction flange 58A, the suction and discharge flanges preferably forming a single piece.

[0221] Alternatively, the cooling circuit 24 comprises at least two pumps 34, each pump 34 being capable of circulating the internal cooling fluid 26. For example, one of the pumps 34 is arranged downstream of the exchanger 28 and the other of the pumps 34 is arranged upstream of the exchanger 28.

[0222] At least one of the pumps 34 is then as described above. The other of the pumps 34 is then as described above or is different.

[0223] In the example detailed above, the pump 34 is included in a cooling circuit 24 of a power transformer 12 of a railway vehicle 10. This use is not limiting.

[0224] Alternatively, the pump 34 is included in a cooling circuit 24 of any power transformer 12. In particular, the power transformer 12 is for example static over time relative to the ground. The term “static” is here to be understood in opposition to the term “mobile”.

[0225] Thanks to the characteristics previously described, the diffuser 94 allows, during assembly, the centering of at least one of the flanges 58A, 58B on the carcass 56, which avoids the machining of a shoulder at the contact interface 88A, 88B between the flange 58A, 58B and the carcass 56. For the same maximum radial template, it is therefore possible to gain in internal volume 82 of the pump 34 and therefore in hydraulic performance.

[0226] The machining of the parts is, incidentally, simplified.

[0227] This design also facilitates the implantation of the seal surface 90A, 90B of the sealing gasket 92A, 92B between the flange 58A, 58B and the carcass 56.

[0228] Thus, the invention makes it possible to optimize the overall hydraulic performance of the pump 34 (power delivered / volume ratio) while reducing the manufacturing cost of the parts.

Claims

Claims

1. A pump (34) for a cooling system (14) of a power transformer (12), the pump (34) comprising a frame (54), the frame (54) comprising at least one housing (56) and a flange, the flange (58A) being a suction flange (58A); the flange (58A) and the carcass (56) each having respectively an outer surface (78A, 78B) and an inner surface (80A, 80B), the inner surfaces (80A, 80B) of the flange (58A) and of the carcass (56) delimiting an inner volume (82) of the pump (34) and being flush with each other; characterized in that the pump (34) further comprises a centering device (74) for centering the flange (58A) relative to the casing (56), the centering device (74) comprising a diffuser (94) fixed to one of the flange (58A) and the casing (56), the diffuser (94) comprising a base ring (96) and blades (98), each blade (98) extending radially relative to the base ring (96) to a centering surface (100), the centering surface (100) being in contact with the casing (56) and the flange (58A), in that the flange (58A) and the casing (56) are in contact along a contact interface (88A), the contact interface (88A) extending from the centering surface (100) to at least one of the surfaces exteriors of the flange (58A) and the carcass (56), the contact interface (88A) being flat; and in that the frame (54) further comprises a discharge flange (58B) extending opposite the suction flange (58A), the suction flange (58A) being arranged upstream of the discharge flange (58B), the discharge flange (58B) having an outer surface (78C) and an inner surface (80C), the inner surfaces (80B, 80C) of the discharge flange (58B) and of the casing (56) delimiting the inner volume (82) of the pump (34) and being flush with each other; the discharge flange (58B) and the carcass (56) being in contact along a downstream contact interface (88B), the contact interface (88B) being planar; the suction flange (58A), the carcass (56) and the discharge flange (58B) each being in one piece.

2. A pump (34) according to claim 1, wherein the flange (5 8A) and the carcass (56) each have a fixing collar (86A-86D) respectively, the flange (58A) and the carcass (56) being fixed relative to each other by a fixing system (84A, 84B) comprising at least one fixing member, each fixing member being respectively received in a passage passing through each fixing collar (86A-86D).

3. Pump (34) according to any one of the preceding claims, in which the base crown (96) is radially recessed relative to the inner surfaces (80A, 80B, 80C) of the flange (58A) and the casing (56), the radial distance separating the base crown (96) from the inner surfaces (80A, 80B, 80C) being preferably greater than or equal to 5 mm, preferably greater than or equal to 10 mm.

4. A pump (34) according to any preceding claim, wherein the pump (34) further comprises an impeller (50) and a motor (52) received in the interior volume (82), the impeller (50) being adapted to circulate an internal cooling fluid (26), the impeller (50) comprising a rotation shaft (60) extending along a main pump axis (X) and being connected to the motor (52), the motor (52) being adapted to exert a torque on the rotation shaft (60) to rotate the rotation shaft (60).

5. The pump (34) of claim 4, wherein the diffuser (94) is configured to redirect the flow of fluid exiting the impeller (50) to flow parallel to the main pump axis (X).

6. A pump (34) according to any one of claims 4 or 5, wherein each blade (98) has two fluid redirection side surfaces, each redirection side surface extending radially from the base crown (96) to the centering surface (100) of the blade, each redirection side surface having a curved shape which is tangent downstream to the main pump axis (X).

7. A pump (34) according to claim 6, wherein, for at least one of the blades (98), the two lateral redirection surfaces of the blade (98) are parallel; and / or wherein, for at least one of the blades (98), the two lateral redirection surfaces of the blade (98) diverge from upstream to downstream.

8. Cooling system (14) of a power transformer (12) comprising: - a cooling circuit (24) in which an internal fluid circulates cooling (26) of the power transformer (12), the internal cooling fluid (26) being circulated by a pump (34) according to any one of the preceding claims; and - a heat exchanger (28) of the heat transported by the internal cooling fluid (26).

9. A railway vehicle (10) comprising a power transformer (12) and a cooling system (14) according to claim 8, the power transformer (12) preferably being capable of generating at output a voltage and current system having a voltage greater than or equal to 1 kV.

10. A method of assembling a pump (34) for a cooling system (14) of a power transformer (12), the method comprising the following steps: - providing a flange (58A) and a carcass (56), the flange (58A) being provided spaced from the carcass (56), the flange (58A) being a suction flange (58A), the flange (58A) and the carcass (56) each having respectively an outer surface (78A, 78B) and an inner surface (80A, 80B); - providing a discharge flange (58B), the discharge flange (58B) having an outer surface (78C) and an inner surface (80C), the suction flange (58A), the carcass (56) and the discharge flange (58B) each being in one piece; - providing a centering device (74) comprising a diffuser (94), the diffuser (94) being provided spaced from the flange (58A) and the carcass (56), the diffuser (94) comprising a base ring (96) and blades (98), each blade (98) extending radially relative to the base ring (96) to a centering surface (100); - fixing the diffuser (94) to one of the carcass (56) and the flange (58A), such that each centering surface (100) is in contact with said one of the carcass (56) and the flange (58A) and protrudes therefrom; - assembly of the casing (56) and the flange (58A), the flange (58A) being centered relative to the casing (56) by the diffuser (94), the assembly being such that each centering surface (100) is also in contact with the other of the casing (56) and the flange (58A); that the inner surfaces (80A, 80B) of the flange (58A) and the casing (56) delimit an inner volume (82) of the pump (34) and are flush with each other; and that the flange (58A) and the casing (56) are in contact along a contact interface (88A), the contact interface (88A) being planar and extending from each centering surface (100) to at least one of the outer surfaces of the flange (58A) and the casing (56), the assembly being such that the discharge flange (58B) extends opposite the suction flange (58A), the suction flange (58A) being arranged upstream of the discharge flange (58B), the inner surfaces (80B, 80C) of the discharge flange (58B) and the casing (56) delimiting the inner volume (82) of the pump (34) and being flush with each other; the discharge flange (58B) and the carcass (56) being in contact along a downstream contact interface (88B), the contact interface (88B) being planar.

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