CN117588446A

CN117588446A - Pump for cooling system of power transformer

Info

Publication number: CN117588446A
Application number: CN202311006698.3A
Authority: CN
Inventors: 赫尔夫·保林; 保罗·科诺凯特
Original assignee: Alstom Holdings SA
Current assignee: Alstom Holdings SA
Priority date: 2022-08-16
Filing date: 2023-08-10
Publication date: 2024-02-23
Also published as: EP4325065A1; FR3138929A1

Abstract

The invention relates to a pump for a cooling system of an electrical transformer, the pump comprising a frame comprising a support (56) and flanges (58A, 58B). The flange and the seat each have an outer surface (78A, 78B) and an inner surface (80A, 80B), respectively, the inner surfaces being flush with each other. The pump comprises a coupling device (74) for coupling the flange with respect to the support, the coupling device (74) comprising a diffuser (94), the diffuser (94) comprising vanes (98) extending radially to a coupling surface (100) in contact with the support and the flange. The flange and the abutment contact along a planar contact interface (88A, 88B) extending from the coupling surface (100) to one of the outer surfaces of the flange and the abutment.

Description

Pump for cooling system of power transformer

[ field of technology ]

The invention relates to a pump for a cooling system of an electric transformer, the pump comprising a frame comprising at least one support and a flange, the flange being a suction flange or a discharge flange; the flange and the seat each have an outer surface and an inner surface, respectively, the inner surfaces of the flange and the seat defining an interior volume of the pump and being flush with each other.

[ background Art ]

Such pumps have interface dimensions, in particular radial specifications, to be followed according to standards, such as standard TS 50537-2 (2010) for traction transformer fittings and cooling systems. This radial specification places demands on the maximum occupied volume of the pump.

In order for the pump to have as high a hydraulic performance as possible, the active hydraulic portion of the pump must occupy as much space as possible without damaging the structural portion. In fact, the space per unit volume for structural or mechanical strength that the flow of fluid relies upon reduces the expected overall performance of the pump.

When the flange is assembled to the support, the two parts are put in place, brought against each other, and then fastened together. However, this placement must be accurately performed and requires the two parts to be coaxial.

For this purpose, conventionally, the two parts have fastening flanges and the coupling is achieved by a shoulder in the flange of one of the two parts (abutment or flange) with a complementary female shoulder in the flange of the other part.

However, it is very complex to fit the shaft, seal, and then pass the set screw through the shoulder while following the maximum radial specification constraint and thus the maximum outer diameter constraint. For example, machining a shoulder of a few millimeters to enable shaft engagement can result in an increase in the outside diameter of the part of a few millimeters as well.

This increase in thickness, as it is necessary to follow the maximum radial specification constraint, can compromise the internal volume of the pump and therefore the hydraulic performance of the pump.

Furthermore, the presence of these shoulders complicates the processing of the two parts.

In addition, in view of the increasingly stringent requirements in terms of the quality of the transport system, it is also advantageous that the pump remains lightweight.

It is therefore an object of the present invention to provide a solution that enables to guarantee a flange-to-seat joint assembly while maintaining or increasing the hydraulic performance of the pump.

[ invention ]

To this end, the invention relates to a pump of the above-mentioned type, characterized in that the pump further comprises coupling means for coupling the flange with respect to the support, the coupling means comprising a diffuser (diffuser) fastened to one of the flange and the support, the diffuser comprising a base crown and vanes, each vane extending radially with respect to the base crown to a coupling surface, the coupling surface being in contact with the support and the flange; and in that the flange and the abutment are in contact along a contact interface extending from the coupling surface to at least one of the outer surfaces of the flange and the abutment, the contact interface being planar.

Pumps according to the present invention may include one or more of the following features considered alone or according to any technically possible combination:

the flange and the seat each have a fastening flange, respectively, the flange and the seat being fastened relative to each other by a fastening system comprising at least one fastener, each fastener being respectively received in a channel through each fastening flange;

the base crown is radially retracted with respect to the flange and the inner surface of the seat, the base crown being preferably spaced from the inner surface by a radial distance of greater than or equal to 5mm, preferably greater than or equal to 10mm;

the pump further comprises an impeller, housed in the internal volume, capable of flowing the internal cooling fluid, comprising a rotation shaft extending along the main pump axis and joined to the motor, and a motor capable of applying a torque to the rotation shaft to rotate the rotation shaft;

-the diffuser is configured to change the flow direction of the fluid leaving the impeller so that it flows parallel to the main pump axis;

each blade has two redirecting side surfaces for redirecting the fluid, each redirecting side surface extending radially from the base crown to the coaxial surface of the blade, each redirecting side surface having a curved shape tangential to the main pump axis downstream;

for at least one of the blades, the two redirecting side surfaces of the blade are parallel; and/or wherein, for at least one of the blades, the two redirecting side surfaces of the blade diverge from upstream to downstream;

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

at least two of the blades have different shapes;

-the diffuser is fastened to one of the flange and the seat by tightening;

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

the pump is an axial flow pump.

The invention also relates to a cooling system for an electrical transformer, comprising:

-a cooling circuit in which an internal cooling fluid of the power transformer flows, the internal cooling fluid being caused to flow by a pump as described above; and

-a heat exchanger for exchanging heat carried by the internal cooling fluid.

The invention also relates to a railway vehicle comprising a power transformer and a cooling system as described above, the power transformer preferably being capable of producing a voltage-current regime with a voltage of 1kV or more at the output.

The invention also relates to a method of assembling a pump for a cooling system of an electrical transformer, the method comprising the steps of:

-providing a flange and a seat, the flange being provided spaced apart from the seat, the flange being a suction flange or a discharge flange, the flange and the seat each having an outer surface and an inner surface, respectively;

-providing a coaxial arrangement comprising a diffuser provided spaced apart from the flange and the abutment, the diffuser comprising a base crown and vanes, each vane extending radially relative to the base crown to the coaxial surface;

-fastening the diffuser to one of the support and the flange such that each of the coupling surfaces is in contact with and beyond said one of the support and the flange;

-assembling the support and the flange, the flange being journalled with respect to the support by means of the diffuser, the assembly being such that: each of the coupling surfaces is also in contact with the other of the support and the flange; the flange and the inner surface of the support define the internal volume of the pump and are flush with each other; and the flange and the abutment contact along a contact interface that is planar and extends from each of the coupling surfaces to at least one of the outer surfaces of the flange and the abutment.

[ description of the drawings ]

The invention will be better understood from reading the following description, given by way of example only, and made with reference to the accompanying drawings in which:

FIG. 1 is a schematic illustration of an example of a railway carrier according to one embodiment of the invention; and is also provided with

Fig. 2 is an axial cross-sectional schematic view of an example of a pump of the railway carrier of fig. 1.

[ detailed description ] of the invention

Fig. 1 schematically illustrates one example of a railway carrier 10.

The railway vehicle 10 includes at least one vehicle, for example, a plurality of vehicles.

The railway vehicle 10 has at least one power transformer 12 and a cooling system 14 including the power transformer 12.

The power transformer 12 is provided in one of the vehicles of the railway vehicle 10.

Since the power transformer 12 is included in the railway vehicle 10 herein, the power transformer 12 may move relative to the ground over time.

The power transformer 12 is capable of transforming an input current that is delivered by an ac power source.

More precisely, the power transformer 12 is able to modify the value of the voltage-current regime of the input current to a voltage-current regime having a different value at the output but having the same frequency and preferably the same shape.

For example, the power transformer 12 can produce a voltage-current regime with a voltage of 1kV or more at the output.

The power transformer 12 includes at least two windings 16 around a core 18.

For simplicity, a single winding 16 is shown in fig. 1.

The two windings 16 are magnetically coupled.

The two windings 16 are, for example, a primary winding and a secondary winding.

Various architectures for windings 16 are known to those skilled in the art and will not be described in further detail herein.

The power transformer 12 preferably includes an electrically insulating material 20 of the windings 16.

The insulating material 20 is formed, for example, from a varnish layer that coats the windings 16. Other insulating materials 20 are known to those skilled in the art and will not be described in further detail herein.

The cooling system 14 is capable of maintaining the temperature of the windings 16 and the insulating material 20 at an acceptable predetermined level.

The dimensions of the cooling system 14 are chosen in particular according to the following parameters: such as losses to be vented, external ambient temperature, noise constraints, size constraints, mass constraints limiting the size of the transformer, and/or cost constraints.

The cooling system 14 includes a cooling circuit 24 for cooling an internal cooling fluid 26 of the power transformer 12 flowing therein, and a heat exchanger 28 for exchanging heat carried by the internal cooling fluid 26.

The cooling circuit 24 is a closed circuit.

The cooling circuit 24 includes a housing 30 for housing the power transformer 12, a flow conduit 32 for flowing the internal cooling fluid 26, and at least one pump 34 capable of flowing the internal cooling fluid 26.

Thus, the flow pattern of the internal cooling fluid 26 is forced flow.

Inside the housing 30, the power transformer 12 is immersed in the internal cooling fluid 26.

Preferably, passages are provided in the core 18 and windings 16 of the transformer that enable the flow of the internal cooling fluid 26 to enable the removal of heat from the core 18 and windings 16 to the internal cooling fluid 26.

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

One skilled in the art can determine the internal fluid suitable for cooling the power transformer 12 in a known manner.

Preferably, for the preferred power ranges described above, the cooling fluid is a liquid, preferably transformer dielectric oil. By way of example, the liquid includes mineral oil or ester oil.

The heat exchanger 28 can remove heat carried by the internal cooling fluid 26 by convection from the external cooling fluid.

Accordingly, the terms "inner" and "outer" are to be understood herein with respect to the flow conduit 32.

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

Preferably, the heat exchanger 28 includes at least one forced convection system (not shown). The flow pattern of the external cooling fluid is then a pattern forced by a forced convection system in operation and forcing the fluid to flow.

The forced convection system is for example a fan.

Alternatively, the flow pattern of the external cooling fluid is a natural pattern, i.e. a non-forced pattern. The heat exchanger 28 then has no forced convection system or a forced convection system is present, but it does not operate in all operating conditions of the transformer 10.

The heat exchanger 28 includes, for example, a tank 36 in which an external cooling fluid flows.

The flow conduit 32 includes, from upstream to downstream, an inlet 38 coupled to the housing 30, an upstream section 40 from the housing 30 to the heat exchanger 28, a cooling section 42 through the heat exchanger 28, a downstream section 44 from the heat exchanger 28 to the housing 30, and an outlet 46 coupled to the housing 30.

The terms "upstream" and "downstream" will be understood herein and hereinafter with respect to the flow direction of the internal cooling fluid 26.

The direction from upstream to downstream is shown by arrow 48 in fig. 1.

The flow conduit 32 is a thermally conductive conduit.

In the example shown, the cooling section 42 passes through the tank 36 of the heat exchanger 28. The external cooling fluid is in contact with the cooling section 42 of the flow conduit 32.

In the example of fig. 1, the cooling section 42 has a serpentine shape.

In other words, the cooling section 42 is zigzagged.

In the example of fig. 1, the cooling circuit 24 includes a single pump 34.

The pump 34 is disposed, for example, between the housing 30 and the heat exchanger 28.

In the example of fig. 1, the pump 34 is here arranged downstream of the heat exchanger 28, in particular at a downstream section 44 of the flow conduit 32. Alternatively, the pump 34 is disposed upstream of the heat exchanger 28, particularly at an upstream section 40 of the flow conduit 32.

In an example not shown, the pump 34 forms an inlet 38 or an outlet 46 of the flow conduit 32.

The pump 34 will now be described in more detail with reference to fig. 2.

The pump 34 is capable of providing pressure to the internal cooling fluid 26 in the flow conduit 32, thus imparting a flow rate thereto.

The pump 34 is a centrifugal pump.

Pump 34 includes an impeller 50 and a motor 52.

In addition, the pump 34 includes a frame 54, the frame 54 including at least one support 56 and a suction flange 58A.

The impeller 50 enables the internal cooling fluid 26 to flow.

The impeller 50 forms the movable element of the pump 34.

The impeller 50 includes a rotating shaft 60 that is coupled to the motor 52.

Impeller 50 also includes a base 62 and blades 64 extending from base 62.

The rotary shaft 60 extends along a main pump axis X.

The motor 52 is capable of applying torque to the rotating shaft 60 to rotate the shaft 60 along the main pump axis X. To this end, the motor 52 then comprises a stator and a rotor, the rotor being coupled to the rotation shaft 60.

The base 62 of the impeller 50 is engaged with the rotation shaft 60, for example, by a pin, so as to rotate together with the rotation shaft 60.

The base 62 of the impeller 50 has a bottom 66 and a sidewall 68.

The rotation shaft 60 passes through, for example, a bottom 66 of the base 62.

The side wall 68 has a substantially cylindrical shape centered on the main pump axis X.

Each vane 64 of impeller 50 extends from a base 66 and is surrounded by a sidewall 68 of base 62.

The blades 64 are radially retracted from the side walls 68.

As described above, the frame 54 includes the suction flange 58A and the seat 56.

The frame 54 further includes a coupling device 74 for coupling the suction flange 58A to the support 56.

In addition, the frame 54 includes a drain flange 58B.

Opposite the movable element formed by the impeller 50, the frame 54 forms the fixed element of the pump 34. Thus, the impeller 50 may rotate relative to the frame 54.

The suction flange 58A is configured to hold the pump 34 to a structure of the cooling circuit 24, such as the housing 30 or the flow conduit 32. The suction flange 58A also ensures a sealing function between the pump 34 and the structure 30, 32.

The suction flange 58A is in fluid communication with the structure 30, 32 on which the pump 34 is held.

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

The suction flange 58A is configured to direct the internal cooling fluid 26 from the housing 30 or the flow conduit 32 to the impeller 50.

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

The suction flange 58A is, for example, circular about the main pump axis X.

The suction flange 58A is integrally cast and made of, for example, aluminum or an aluminum alloy.

The support 56 is configured to support a stator of the motor 52.

In particular, the stator of the motor 52 is fastened to the support 56.

The support 56 is integrally cast and is made of, for example, aluminum or an aluminum alloy.

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

The suction flange 58A and the inner surfaces 80A, 80B of the seat 56 define an interior volume 82 of the pump 34.

The internal cooling fluid 26 is contained within the internal volume 82.

The impeller 50 and motor 52 are housed in an interior volume 82 of the pump 34.

As shown in FIG. 2, the suction flange 58A and the inner surfaces 80A, 80B of the seat 56 are flush with one another.

In other words, the suction flange 58A and the inner surfaces 80A, 80B of the seat 56 are level with one another and do not form a step at their junction.

The suction flange 58A and the mount 56 are fastened relative to each other by a fastening system 84A, the fastening system 84A including at least one fastener, and preferably a plurality of fasteners.

For this purpose, the suction flange 58A and the carrier 56 each have a fastening flange 86A, 86B, respectively.

Each of the fastening flanges 86A, 86B protrudes radially outwardly. In this and hereinafter, the term "radial" is to be understood with respect to the main pump axis X.

In one embodiment, each fastening flange 86A, 86B extends over the entire perimeter of the suction flange 58A and the seat 56. Alternatively, at least one of the flanges is discontinuous.

Each fastener is received in a respective through passage through the fastening flanges 86A, 86B. Each through passage is, for example, a threaded passage.

In this way, each fastener extends through the fastening flange 86A of the suction flange 58A and the fastening flange 86B of the seat 56.

Each fastener is, for example, a screw or bolt.

As shown in FIG. 2, the suction flange 58A and the seat 56 are in contact along an upstream contact interface 88A.

The upstream contact interface 88A is defined as the contact surface between the suction flange 58A and the seat 56.

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

The upstream contact interface 88A extends along the fastening flanges 86A, 86B of the suction flange 58A and the carrier 56.

The upstream contact interface 88A is planar.

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

In other words, the upstream contact interface 88A has no shoulder.

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

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

In the example of fig. 2, the upstream contact interface 88A is discontinuous to ensure a seal between the suction flange 58A and the seat 56.

In particular, one of the suction flange 58A and the seat 56 defines a gasket seating surface 90A that receives a sealing gasket 92A, the gasket seating surface 90A being closed by the other of the suction flange 58A and the seat 56.

In this case, the gasket bearing surface 90A is, for example, a groove.

In the example of fig. 2, the gasket bearing surface 90A is defined by the seat 56. Alternatively, the gasket bearing surface 90A may be defined by the suction flange 58A or by both the seat 56 and the suction flange 58A together.

The seal gasket 92A is, for example, a flat gasket or an O-ring gasket.

The seal gasket 92A is made of, for example, an elastomer.

The described coupling device 74 according to the invention, which couples the suction flange 58A with respect to the seat 56, makes it possible to ensure this coupling during assembly of the pump 34, even if the upstream contact interface 88A between the suction flange 58A and the seat 56 is planar and perpendicular to the main pump axis X.

The coupling 74 includes a diffuser 94 secured to one of the suction flange 58A and the seat 56.

Preferably, the diffuser 94 is then secured to one of the suction flange 58A and the seat 56 by tightening. This is then a tightening with negative play, that is to say the diffuser 94 is clamped by the part of the shaft to which it is fitted.

Alternatively, the diffuser 94 is secured by any other means as would occur to one skilled in the art, such as by threaded members extending through the support 56 and the diffuser 94.

In the present invention, the diffuser 94 then ensures a dual function: the first function is to pivot suction flange 58A relative to seat 56 and the second function is to direct the flow of fluid 26 in pump 34.

The diffuser 94 is configured to change the direction of flow of the fluid 26 exiting the impeller 50. Upon exiting the impeller 50, the direction of the fluid is a direction orthogonal to the radial direction, and the diffuser 94 is configured to redirect the fluid so that it flows parallel to the main pump axis X.

The diffuser 94 is integrally cast and is made of, for example, aluminum or an aluminum alloy.

In line with the diffuser 94, each of the suction flange 58A and the inner surfaces 80A, 80B of the seat 56 has a circular cross-section. The cross section is taken perpendicular to the main pump axis X.

The diffuser 94 includes a base crown 96 and a plurality of vanes 98.

The base crown 96 has a substantially cylindrical shape centered on the main pump axis X.

The base crown 96 is radially tapered relative to the suction flange 58A and the inner surfaces 80A, 80B of the seat 56.

The radial distance separating the base crown 96 from the inner surfaces 80A, 80B is, for example, 5mm or more, preferably 10mm or more.

The base crown 96 has a central opening through which the rotational shaft 60 of the impeller 50 passes.

The rotation guide system enables rotation of the rotation shaft 60 relative to the base crown 96, the rotation guide system being supported by the base crown 96 or the rotation shaft 60.

The rotation guide system is, for example, a ball bearing system, a roller bearing system or a plain bearing system.

The diffuser 94 advantageously includes a number of vanes 98 equal to or greater than 3.

At least two of the vanes 98, and advantageously at least three of the vanes 98, extend radially from the base crown 96 to a coaming surface 100, respectively, the coaming surface 100 of the vane 98 being in contact with the seat 56 and the suction flange 58A.

For example, at least one of the vanes 98 does not reach the inner surface 80B of the seat 56 and/or the inner surface 80A of the suction flange 58A.

As such, the upstream contact interface 88A between the suction flange 58A and the abutment 56 extends from the coupling surface 100 to one of the outer surfaces 78A, 78B of the suction flange 58A and the abutment 56.

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

The respective blades 98 are disposed at predetermined intervals along the circumference of the base crown 96.

The distribution of the vanes 98 preferably has at least one rotational symmetry with respect to the main pump axis X.

The vanes 98 are arranged to redirect fluid exiting the impeller 50 so that it flows parallel to the main pump axis X.

Each vane 98 has two fluid redirecting side surfaces, each redirecting side surface extending radially from the base crown 96 to the vane's coaxial surface 100.

Between two adjacent redirecting side surfaces, the diffuser 94 defines a flow channel for the internal cooling fluid 26.

In this way, the flow channel is laterally delimited by two adjacent redirecting side surfaces and also radially delimited by the base crown 96 and the inner surfaces 80A, 80B of the suction flange 58A and the seat 56.

By "two adjacent redirecting side surfaces" is meant two side surfaces of two different blades 98, no blade 98 being interposed circumferentially between the two different blades 98.

Each redirecting side surface preferably has a curved shape tangential downstream of the main pump axis X.

In other words, the redirecting side surfaces of each vane 98 respectively present a straight downstream region parallel to the main pump axis X.

Alternatively, each redirecting side surface is, for example, straight in shape, the blade 98 then having an arrow shape with a tip directed upstream.

For example, each of the blades 98 has the same shape. Alternatively, at least two of the blades 98 are differently shaped.

A discharge flange 58B is provided downstream of the suction flange 58A.

The drain flange 58B also has an outer surface 78C and an inner surface 80C. An inner surface 80C of the exhaust flange 58B defines the internal volume 82 of the pump 34 in which the internal cooling fluid 26 is contained.

The drain flange 58B is configured to retain the pump 34 on a structure of the cooling circuit 24, such as the housing 30 or the flow conduit 32. The drain flange 58B also ensures a sealing function between the pump 34 and the structure 30, 32.

The drain flange 58B is in fluid communication with the structure 30, 32 on which the pump 34 is held.

The internal cooling fluid 26 exits the pump 34 via the exhaust flange 58B.

The exhaust flange 58B is configured to direct the internal cooling fluid 26 downstream of the impeller 50 to the casing 30 or the flow conduit 32.

In the example of fig. 2, the pump 34 is an axial flow pump.

The discharge flange 58B is particularly aligned with the intake flange 58A along the main pump axis X.

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

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

The discharge flange 58B is, for example, circular about the main pump axis X.

The drain flange 58B is integrally cast and is made of, for example, aluminum or an aluminum alloy.

The drain flange 58B and the seat 56 are fastened relative to one another by a fastening system 84B, the fastening system 84B including at least one fastener, and preferably a plurality of fasteners.

To this end, the drain flange 58B has a fastening flange 86C and the seat 56 has another downstream fastening flange 86D.

Each of the fastening flanges 86C, 86D protrudes radially outward.

Each fastener is received in a through passage extending through a respective fastening flange 86C, 86D. Each through passage is, for example, a threaded passage.

In this way, each fastener extends through the fastening flange 86C of the drain flange 58B and the downstream fastening flange 86D of the seat 56.

Each fastener is, for example, a screw or bolt.

As shown in fig. 2, the exhaust flange 58B and the seat 56 contact along a downstream contact interface 88B.

The downstream contact interface 88B is defined as the contact surface between the exhaust flange 58B and the seat 56.

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

The downstream contact interface 88B extends along the fastening flange 86C of the drain flange 58B and the downstream fastening flange 86D of the seat 56.

The downstream contact interface 88B is planar.

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

In other words, the downstream contact interface 88B has no shoulder.

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

The maximum radial length is defined as the radial length between the two extreme points of contact between the drain flange 58B and the seat 56.

In the example of fig. 2, the downstream contact interface 88B is discontinuous to ensure a seal between the drain flange 58B and the seat 56.

In particular, one of the drain flange 58B and the seat 56 defines a gasket seating surface 90B that receives a sealing gasket 92B, the gasket seating surface 90B being closed by the other of the drain flange 58B and the seat 56.

In this case, the gasket bearing surface 90B is, for example, a groove.

In the example of fig. 2, the gasket bearing surface 90B is defined by the seat 56. Alternatively, the gasket bearing surface 90B may be defined by the drain flange 58B, or may be defined by both the drain flange 58B and the seat 56.

The seal gasket 92B is, for example, a flat gasket or an O-ring gasket.

The seal gasket 92B is made of, for example, an elastomer.

The method of assembling the pump 34 as described above will now be described.

The assembly method includes providing a suction flange 58A and a seat 56, the suction flange 58A being provided spaced apart from the seat 56.

The method includes providing a coupling 74 including a diffuser 94, the diffuser 94 being provided spaced apart from the suction flange 58A and the seat 56.

The method includes securing the diffuser 94 into one of the seat 56 and the suction flange 58A such that each of the coupling surfaces 100 contacts and extends beyond the one of the seat 56 and the suction flange 58A.

The vane 98 then has a free portion that protrudes along the main pump axis X and then serves as a coaxial arrangement.

The diffuser 94 is secured, for example, by tightening.

The method then includes assembling the support 56 and the suction flange 58A.

During this assembly, suction flange 58A is journaled relative to seat 56 by diffuser 94.

The assembly is such that: each of the coupling surfaces 100 also contacts the other of the abutment 56 and the suction flange 58A; the suction flange 58A and the inner surfaces 80A, 80B of the seat 56 define an internal volume 82 of the pump 34 and are flush with each other; and the suction flange 58A and the abutment 56 contact along an upstream contact interface 88A, the upstream contact interface 88A being planar and extending from each of the coupling surfaces 100 to at least one of the suction flange 58A and the outer surface of the abutment 56.

The suction flange 58A and the seat 56 are then fastened together.

The fastening is achieved, for example, by the above fastening system 84A.

The above-described embodiments correspond to the coupling of the suction flange 58A with respect to the seat 56, and in a variant not described in detail, the discharge flange 58B is coupled with respect to the seat 56 independently and in a similar manner to that described above.

The drain flange 58B is then journaled with respect to the support 56 by another special feature.

The other special part is for example a diffuser or a rotary guide element support.

In the case where the 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 the other dedicated part.

As a variant, the pump 34 is not an axial flow pump.

The pump 34 is, for example, a radial pump, and the discharge flange 58B is then centered on an axis perpendicular to the main pump axis X.

The discharge flange 58B is then, for example, provided on the same side of the support 56 as the suction flange 58A, the suction flange and the discharge flange preferably forming an integral casting.

Alternatively, the cooling circuit 24 includes at least two pumps 34, each pump 34 being capable of flowing the internal cooling fluid 26. For example, one of the pumps 34 is disposed downstream of the exchanger 28, while the other of the pumps 34 is disposed upstream of the exchanger 28.

Thus, at least one of the pumps 34 is a pump as described above. While the other of the pumps 34 is a pump as described above or a different pump.

In the example detailed above, the pump 34 is included in the cooling circuit 24 of the power transformer 12 of the railway vehicle 10. Not limited to this use.

Alternatively, pump 34 is included in cooling circuit 24 of any power transformer 12. In particular, the power transformer 12 is static with respect to ground, for example, over time. The term "stationary" is understood herein as contrary to the term "movable".

By virtue of the above-described features, the diffuser 94 enables at least one of the flanges 58A, 58B to be journalled relative to the support 56 during assembly, which avoids machining shoulders at the contact interfaces 88A, 88B between the flanges 58A, 58B and the support 56. Thus, for the same maximum radial specification, the internal volume 82 of the pump 34 and thus the hydraulic performance may be increased.

Additionally simplifying the machining of the parts.

This design also facilitates the provision of gasket bearing surfaces 90A, 90B of sealing gaskets 92A, 92B between flanges 58A, 58B and seat 56.

Thus, the present invention enables optimization of the overall hydraulic performance (output power/volume ratio) of the pump 34 while reducing the manufacturing costs of the individual parts.

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 seat (56) and a flange, the flange (58A, 58B) being a suction flange (58A) or a discharge flange (58B);

the flange (58A, 58B) and the seat (56) each have an outer surface (78A, 78B) and an inner surface (80A, 80B), respectively, the inner surfaces (80A, 80B, 80C) of the flange (58A, 58B) and the seat (56) defining an interior volume (82) of the pump (34) and being flush with each other;

characterized in that the pump (34) further comprises a coupling device (74) for coupling the flanges (58A, 58B) with respect to the support (56), the coupling device (74) comprising a diffuser (94) fastened to one of the flanges (58A, 58B) and the support (56), the diffuser (94) comprising a base crown (96) and vanes (98), each vane (98) extending radially with respect to the base crown (96) to a coupling surface (100), the coupling surface (100) being in contact with the support (56) and the flanges (58A, 58B);

and in that the flange (58A, 58B) and the abutment (56) are in contact along a contact interface (88A, 88B), the contact interface (88A, 88B) extending from the coupling surface (100) to at least one of the flange (58A, 58B) and an outer surface of the abutment (56), the contact interface (88A, 88B) being planar.

2. The pump (34) of claim 1 wherein the flange (58A, 58B) and the mount (56) each have a fastening flange (86A-86D), respectively, the flange (58A, 58B) and the mount (56) being fastened relative to each other by a fastening system (84A, 84B) including at least one fastener, each fastener being received in a channel through each fastening flange (86A-86D), respectively.

3. The pump (34) of claim 1 wherein the base crown (96) is radially tapered relative to the flanges (58A, 58B) and the inner surfaces (80A, 80B, 80C) of the abutment (56).

4. A pump (34) according to claim 3, wherein the base crown (96) is spaced from the inner surface (80A, 80B, 80C) by a radial distance of 5mm or more.

5. The pump (34) of claim 4, wherein the base crown (96) is spaced from the inner surface (80A, 80B, 80C) by a radial distance of 10mm or greater.

6. The pump (34) of any of claims 1-5, wherein the pump (34) further comprises an impeller (50) and a motor (52) housed in the interior volume (82), the impeller (50) configured to flow the interior cooling fluid (26), the impeller (50) comprising a rotating shaft (60) extending along the main pump axis (X) and coupled to the motor (52), the motor (52) configured to apply torque to the rotating shaft (60) to rotate the rotating shaft (60).

7. The pump (34) of claim 6, 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).

8. The pump (34) of claim 6 wherein each vane (98) has two redirecting side surfaces for redirecting fluid, each redirecting side surface extending radially from the base crown (96) to the vane's hub surface (100), each redirecting side surface having a curved shape tangential downstream of the main pump axis (X).

9. The pump (34) of claim 8 wherein, for at least one of the vanes (98), the two redirecting side surfaces of the vane (98) are parallel; and/or wherein, for at least one of the blades (98), the two redirecting side surfaces of the blade (98) diverge from upstream to downstream.

10. A cooling system (14) of a power transformer (12), comprising:

-a cooling circuit (24) in which an internal cooling fluid (26) of the power transformer (12) flows, the internal cooling fluid (26) being flowed by a pump (34) according to any one of claims 1 to 5; and

-a heat exchanger (28) for exchanging heat carried by the internal cooling fluid (26).

11. Railway vehicle (10) comprising a power transformer (12) and a cooling system (14) according to claim 10.

12. Railway vehicle according to claim 11, wherein the power transformer (12) is able to generate at the output a voltage-current regime with a voltage greater than or equal to 1 kV.

13. A method of assembling a pump (34) for a cooling system (14) of a power transformer (12), the method comprising the steps of:

-providing a flange (58A, 58B) and a seat (56), the flange (58A, 58B) being provided spaced apart from the seat (56), the flange (58A, 58B) being a suction flange (58A) or a discharge flange (58B), the flange (58A, 58B) and the seat (56) each having an outer surface (78A, 78B) and an inner surface (80A, 80B), respectively;

-providing a coaxial arrangement (74) comprising a diffuser (94), the diffuser (94) being provided spaced apart from the flange (58A, 58B) and the abutment (56), the diffuser (94) comprising a base crown (96) and vanes (98), each vane (98) extending radially with respect to the base crown (96) to a coaxial surface (100);

-fastening the diffuser (94) to one of the support (56) and the flange (58A, 58B) such that each of the coupling surfaces (100) is in contact with and beyond said one of the support (56) and the flange (58A, 58B);

-assembling the support (56) and the flanges (58A, 58B), the flanges (58A, 58B) being journalled with respect to the support (56) by means of a diffuser (94), the assembly being such that: each coupling surface (100) is also in contact with the other of the abutment (56) and the flange (58A, 58B); the flanges (58A, 58B) and the inner surfaces (80A, 80B, 80C) of the support (56) define an interior volume (82) of the pump (34) and are flush with each other; and the flange (58A, 58B) and the abutment (56) are in contact along a contact interface (88A, 88B), the contact interface (88A, 88B) being planar and extending from each of the hinge surfaces (100) to at least one of the flange (58A, 58B) and an outer surface of the abutment (56).