ELECTRIC SWITCH WITH WEAR CONTACTS

Description

[0001] The present invention relates to a railway vehicle comprising an electrical switch comprising: a first terminal and a second terminal suitable for being electrically connected to a first electrical circuit and a second electrical circuit respectively, and an arm electrically connected to the first terminal, and movable relative to the second terminal between a closed position of the switch, in which the arm electrically connects the first terminal and the second terminal to each other, and an open position of the switch, in which the arm is away from the second terminal.

[0002] The invention also relates to a retrofit method for obtaining the vehicle.

[0003] Such a switch is suitable for the electrical supply of vehicles, particularly railway vehicles, i.e. at voltages of the order of 15000V to 25000V. At such voltages, opening or closing the switch causes the appearance of one or more electric arcs between the arm and the second terminal. Indeed, as long as the arm and the second terminal are sufficiently close to each other, the electrical voltage between these two elements causes ionization of the air and a displacement of electrical charges between the arm and the second terminal. These electric arcs are likely to cause removal of material and / or deterioration on the arm and on the second terminal.

[0004] This can impair the operation of the switch, and in any case reduce its lifespan.

[0005] Document FR 2 865 973 A1 discloses a railway vehicle according to the preamble of claim 1 and a method according to the preamble of claim 7.

[0006] Thus, an aim of the invention is to provide a switch of the type described above offering an improved service life, all other things being equal.

[0007] For this purpose, the invention relates to a vehicle according to claim 1.

[0008] According to particular embodiments, the vehicle comprises one or more of the characteristics corresponding to claims 2 to 6, taken in isolation or in all technically possible combinations.

[0009] The invention finally relates to a method according to claim 7.

[0010] The invention will be better understood on reading the following description, given solely by way of example and with reference to the appended drawings, in which: therefigure 1 is a schematic view of the roof of a vehicle according to the invention, comprising a switch according to the invention, shown in perspective, certain elements of the switch being omitted, and the arm being in the open position of the switch, the figure 2 is a schematic view, from above, of the vehicle shown in the figure 1 , the arm having almost reached the intermediate position, the figure 3 is a schematic view, from above, of the switch shown in the figures 1 And 2 , the arm being in the switch closing position, the figure 4 is a schematic view illustrating a step in a manufacturing process, here a retrofit process, leading to a switch similar to that shown in the figures 1 à 3 , and the figure 5 is a partial top view of a switch constituting a variant of the switches shown in the figures 1 à 4 .

[0011] In reference to the figures 1 à 3 , a vehicle 10 according to the invention is described. In the example shown, the vehicle 10 is a railway vehicle electrically powered at high voltage by systems not shown. By “high voltage” is meant, for example, a voltage greater than or equal to 10 kV, advantageously approximately 25 kV.

[0012] Alternatively, the vehicle 10 is not a railway vehicle, but for example a trolleybus or any other vehicle usually supplied with high voltage.

[0013] The vehicle 10 includes a roof 12, a first electrical circuit 14, a second electrical circuit 16, and an electrical switch 18 electrically located between the first electrical circuit 14 and the second electrical circuit 16.

[0014] The first electrical circuit 14 comprises, for example, a pantograph (not shown) adapted to be connected to a catenary (not shown) intended to provide electrical power to the vehicle 10.

[0015] The second electrical circuit 16 is for example a circuit for distributing electrical power in the vehicle 10. The second electrical circuit 16 is for example connected to an electrical transformer (not shown), or to other electricity-consuming equipment (also not shown).

[0016] According to a variant not shown, the vehicle 10 comprises several switches similar to the switch 18, which makes it possible, for example, to distribute the electrical power to several electrical sub-circuits from the first electrical circuit 14 or from another electrical circuit.

[0017] The switch 18 comprises a support 20 fixed on or in the roof 12, a first terminal 22 electrically connected to the first electrical circuit 14, and a second terminal 24 electrically connected to the second electrical circuit 16. The switch 18 also comprises an arm 26 electrically connected to the first terminal 22, and rotatable about an axis D1 relative to the second terminal 24 between a closed position of the switch (shown in the figure 3 ), an opening position (shown on the figure 1 ), and various intermediate positions (one of which is shown in the figure 2 ).

[0018] The switch 18 further comprises a first wear contact 28 electrically and mechanically connected to the arm 26 by a first connection system 30. The switch also comprises a second wear contact 32 electrically and mechanically connected to the second terminal 24 by a second connection system 34.

[0019] The first terminal 22 comprises, for example, an electrically insulating part 36 rotatably mounted on the support 20 around the axis of rotation D1, and an electrically conductive part 38 on which the arm 26 is fixed and connected to the first electrical circuit 14.

[0020] The second terminal 24 comprises, for example, an electrically insulating part 40 fixed to the support 20, and jaws 42 adapted to receive, in the closed position of the switch, a distal end 44 of the arm 26 relative to the first terminal 22.

[0021] By "insulator" we mean that the element is not suitable for conducting electricity and has, for example, a resistivity greater than 10 5< Ω.m.

[0022] The arm 26 is for example rectilinear. The arm 26 is for example fixed on the first terminal 22 and advantageously adapted to be driven in rotation around the axis D1 by the first terminal.

[0023] The first wear contact 28 and the second wear contact 32 are advantageously structurally similar to each other. They form, for example, two plates, and are advantageously made of a silver and / or tungsten alloy. The first connection system 30 and the second connection system 34 are adapted so that the first wear contact 28 and the second wear contact 32 are spaced apart from each other in the open position in order to avoid an electric arc between these two wear contacts.

[0024] The connection systems 30, 34 are also adapted so that the wear contacts 28, 32 are close to each other in the intermediate position shown in the figure 2 , in order to allow the appearance of an electric arc 46 between them, the arm 26 and the second terminal 24 being sufficiently far from each other to avoid any electric arc between the arm and the second terminal. The wear contacts 28, 32 are, in this intermediate position, the closest conductive parts connected on the one hand to the arm 26 and on the other hand to the second terminal 24.

[0025] The dimensions of the connection systems 30 and 34 are chosen as a function of the voltage present between the terminals 22 and 24. Care will be taken to ensure that the intermediate position corresponds to the striking position, i.e. the creation of an electric arc between the wear contacts 28 and 32 or the bringing into contact of the wear contacts 28 and 32, the distance between the jaws 42 and the end 44 of the arm being for example at least 10% greater than the distance between the connection systems 30 and 34 at the time of striking.

[0026] The connection systems 30, 34 are also adapted so that, in an intermediate position in which the arm 26 is slightly closer to the second terminal 24 than on the figure 2 , the wear contacts 28, 32 are in contact with each other.

[0027] In the example shown, the contact is flat for greater ease of production.

[0028] Alternatively, the contact is punctual, for example if the wear contacts 28, 32 are curved.

[0029] The connection systems 30, 34 are finally adapted so that the wear contacts 28, 32 remain in contact with each other from this intermediate position (in which the wear contacts come into contact with each other or are electrically connected to each other via an electric arc) until the closed position, the contact preferably remaining flat.

[0030] In the example shown, the first connection system 30 and the second connection system 34 are structurally analogous to each other.

[0031] The first connection system 30 comprises a first flexible member 48, electrically conductive, having a proximal end 50 fixed on the arm 26, and a distal end 52 fixed on the first wear contact 28.

[0032] By "conductor" we mean that the element is suitable for conducting electricity, its resistivity being for example less than 10 -7< Ω.m.

[0033] The first flexible member 48 is configured to allow the first wear contact 28 to be closer to the arm 26 in the closed position than in the intermediate position shown in the figure 2 .

[0034] The second connection system 34 comprises a second flexible member 54, for example substantially symmetrical to the first flexible member 48 with respect to a plane P ( figure 2 ).

[0035] The second flexible member 54, in the example shown, has a proximal end 56 attached to the second terminal 24, and a distal end 58 attached to the second wear contact 32. The second flexible member 54 is configured to allow the second wear contact to be closer to the second terminal in the closed position than in the intermediate position shown in the figure 2 .

[0036] According to a particular embodiment, the first flexible member 48 and the second flexible member 54 are made of the same material as the first wear contact 28 and the second wear contact 32 respectively. For example, the assemblies thus formed comprise a conductive and arc-resistant material 46, for example a copper-tungsten alloy. These assemblies are advantageously made of this alloy.

[0037] The operation of switch 18 is deduced from its structure and will now be described.

[0038] The opening position ( figure 1 ) makes it possible to electrically isolate the first electrical circuit 14 from the second electrical circuit 16. No electric current passes from the first terminal 22 to the second terminal 24. Indeed, in the open position, the arm 26 and the first wear contact 28 are respectively away from the jaws 42 and the second wear contact 32. Given the electrical voltages involved, no electric arc appears between these elements.

[0039] Then the first terminal 22 is actuated in rotation relative to the support 20 around the axis of rotation D1 by means not shown, which drives the arm 26 in rotation towards the second terminal 24. This also has the effect of bringing the wear contacts 28, 32 closer to each other.

[0040] When arm 26 reaches the intermediate position shown in the figure 2 , the electric arc 46 appears between the wear contacts 28, 32, and not between the arm 26 and the second terminal 24, which are thus protected.

[0041] Then, the arm 26 approaches the second 24 again, the wear contacts 28, 32 come into contact with each other. Finally, the arm 26 reaches the closing position shown in the figure 3 . During the passage of the arm from the intermediate position in which the wear contacts 28, 32 come into electrical contact with each other to the closing position, the wear contacts remain in electrical contact with each other, which prevents the occurrence of an electric arc between the arm and the second terminal, even when the arm is very close to the jaws 42. Thus, the arm and the second terminal are protected throughout the closing operation of the switch 18.

[0042] Conversely, to open the switch 18, the arm 26 is rotated relative to the support 20 around the axis of rotation D1 in the opposite direction by the first terminal 22. The wear contacts 28, 32, initially in contact in the closed position, remain in contact with each other while the arm 26 begins to move away from the jaws 42, preventing the occurrence of an electric arc between the arm and the second terminal.

[0043] Then, the physical contact between the two wear contacts 28, 32 ceases and the electric arc 46 appears again between the wear contacts. No electric arc then appears between the arm 26 and the second terminal 24, because the arm and the second terminal are then sufficiently far from each other.

[0044] Then, the electric arc 46 stops when the wear contacts 28, 32 are in turn sufficiently far from each other. The arm 26 arrives shortly after in the open position ( figure 1 ).

[0045] A manufacturing method according to the invention will now be described.

[0046] The method comprises providing the first terminal 22 and the second terminal 24, and the arm 26.

[0047] The method further comprises providing the first wear contact 28 and the second wear contact 32, and electrically and mechanically connecting them, respectively, to the arm 26 and to the second terminal 24, respectively by the first connection system 30 and the second connection system 34.

[0048] This is an initial manufacturing when all these operations are carried out to obtain the switch 18 and this is then fixed on the roof 12 of the vehicle 10.

[0049] According to a variant, the manufacturing method is a retrofit or improvement method produced when the operations of supplying or designing the first terminal 22, the second terminal 24 and the arm 26 have been carried out for a long time during the manufacture of a conventional switch, and the steps of supplying the wear contacts 28, 32 and the connection systems 30, 34 are carried out some time later to improve the switch.

[0050] This is done, for example, as shown in the figure 4 .

[0051] The first wear contact 28 is for example provided already fixed on the first flexible member 48. The distal end 50 is then easily fixed on the arm 26, for example using a fastener 60.

[0052] Advantageously, the attachment 60 is adapted to allow angular adjustment of the first flexible member 48 around an axis D2 substantially parallel to the axis of rotation D1. This makes it possible to select an intermediate position of the arm 26 in rotation around the axis of rotation D1 relative to the second terminal 24 from which the wear contacts 28, 32 come into electrical and / or physical contact with each other during closing, or separate from each other during opening.

[0053] Due to the features described above, wear of the arm 26 and jaws 42 is reduced and the switch 18 has an improved service life.

[0054] In reference to the figure 5 , we will now describe a switch 118 (partially shown) constituting a variant of the switch 18. The switch 118 is analogous to the switch 18 shown in the figures 1 à 3 . Similar items have the same reference numerals and will not be described again. Only differences will be described in detail below.

[0055] In the switch 118, the first wear contact 28 is mounted on the arm 26 using a connection system 130.

[0056] The connection system 130 comprises a rigid member 148 and a return member 150.

[0057] The rigid member 148 is electrically conductive and carries the first wear contact 28. The rigid member is mounted to rotate on the arm 26 around a pivot axis D3, between a rest position (shown in the figure 5 ), and a compressed position (not shown but deduced from the rest position by a rotation of the rigid member 148 around the axis D3), in which the first wear contact 28 is closer to the arm 26 than in the rest position.

[0058] The rigid member 148 is for example a rod or a rectilinear blade.

[0059] The rigid member 148 is for example mounted on the arm using a hinge 152 defining the pivot axis D3.

[0060] The return member 150 is for example a spring 154 mounted in compression between a distal end 156 of the rigid member 148 and the arm 26.

[0061] In this variant, the connection system of the second wear contact 32 is for example analogous to the connection system 130.

[0062] According to other variants not shown, only one of the connection systems 30, 34 has flexibility. Indeed, to cushion the contact between the wear contacts 28, 32 and obtain prolonged contact, it is sufficient for only one of the two connection systems to be flexible.

Claims

1. A rail vehicle (10) comprising at least one switch (18; 118), a first electrical circuit (14), and a second electrical circuit (16), the electrical switch (18; 118) comprising: - a first terminal (22) and a second terminal (24) respectively electrically connected to the first electrical circuit (14) and the second electrical circuit (16), and - an arm (26) electrically connected to the first terminal (22), the arm (26) being secured to the first terminal (22) and adapted to be rotated by the first terminal (22) about an axis (D1) relative to the second terminal (24) between a closed position of the switch (18; 118), wherein the arm (26) electrically links the first terminal (22) and the second terminal (24) to each other, and an open position of the switch (18; 118), wherein the arm (26) is away from the second terminal (24), characterized in that: - the switch (18; 118) further comprises a first wear contact (28) and a second wear contact (32) electrically and mechanically connected to the arm (26) and to the second terminal (24), respectively, by a first connection system (30; 130) and by a second connection system (34), and - the arm (26) is movable successively between the open position wherein the first wear contact (28) is away from the second wear contact (32) to avoid an electric arc between the first wear contact (28) and the second wear contact (32), an intermediate position wherein the first wear contact (28) is in electrical contact with the second wear contact (32), in particular via an electric arc, while the arm (26) and the second terminal (24) are still away from each other to avoid an electric arc between the arm (26) and the second terminal (24), and the closed position, and in that: - the first connection system (30) comprises a first flexible, electrically conductive member, the first flexible member having a proximal end attached to the arm (26) and a distal end attached to the first wear contact (28), the first flexible member being configured to allow the first wear contact (28) to be closer to the arm (26) in the closed position than in the intermediate position, and - the second connection system (34) comprises a second, electrically conductive, flexible member (54), the second flexible member (54) having a proximal end (56) attached to the second terminal (24) and a distal end (58) attached to the second wear contact (32), the second flexible member (54) being configured to allow the second wear contact (32) to be closer to the second terminal (24) in the closed position than in the intermediate position; or in that: - the first connection system (30) comprises a first electrically conductive member having a proximal end secured to the arm (26) and a distal end secured to the first wear contact (28), the first member being configured to allow the first wear contact (28) to be closer to the arm (26) in the closed position than in the intermediate position, the first member and the first wear contact being formed in a single piece advantageously from a copper-tungsten alloy, and - the second connection system (34) comprises a second electrically conductive member (54), the second member (54) having a proximal end (56) secured to the second terminal (24) and a distal end (58) secured to the second wear contact (32), the second member being configured to allow the second wear contact (32) to be closer to the second terminal (24) in the closed position than in the intermediate position, the second member and the second wear contact being formed in a single piece advantageously from a copper-tungsten alloy.

2. The vehicle (10) according to claim 1, wherein the first connection system (30; 130) and the second connection system (34) are adapted so that the first wear contact (28) and the second wear contact (32) remain in electrical contact when the arm (26) goes from the intermediate position to the closed position.

3. The vehicle (10) according to claim 1 or 2, wherein the first connection system (30; 130) and the second connection system (34) are adapted so that the first wear contact (28) and the second wear contact (32) remain in electrical contact when the arm (26) goes from the closed position to the intermediate position.

4. The vehicle (10) according to any one of claims 1 to 3, wherein the first connection system (130) comprises an electrically conductive rigid member (148) carrying the first wear contact (28), the rigid member (148) being mounted to rotate on the arm (26) about a pivot axis (D3) between a rest position and a compressed position, wherein the first wear contact (28) is closer to the arm (26) than in the rest position, the first connection system (130) further comprising a return member (150) adapted to resiliently return the rigid member (148) from the compressed position to the rest position.

5. The vehicle (10) according to any one of claims 1 to 4, further comprising a support (20), and wherein the first terminal (22) comprises an electrically insulating part (36) mounted to rotate on the support (20) about the axis of rotation (D1), and an electrically conducting part (38) to which the arm (26) is secured and suitable for being linked to the first electrical circuit (14).

6. The vehicle (10) according to any one of claims 1 to 5, further comprising a roof (12), and wherein said switch (18; 118) is located in or on the roof (12).

7. A method for retrofitting an electrical switch (18; 118) of a rail vehicle (10), the switch (18; 118) comprising a first terminal (22) and a second terminal (24) respectively electrically connected to a first electrical circuit (14) and to a second electrical circuit (16) of the vehicle (10), and an arm (26) electrically connected to the first terminal (22), the arm (26) being secured to the first terminal (22) and adapted to be rotated by the first terminal (22) about an axis (D1) relative to the second terminal (24) between a closed position of the switch (18; 118), wherein the arm (26) electrically links the first terminal (22) and the second terminal (24) to each other, and an open position of the switch (18; 118), wherein the arm (26) is away from the second terminal (24), characterised in that it comprises the following steps: - providing a first wear contact (28) and a second wear contact (32), and - electrically and mechanically connecting the first wear contact (28) and the second wear contact (32) respectively to the arm (26) and to the second terminal (24), respectively by a first connection system (30; 130) and by a second connection system (34), the arm (26) being movable successively between the open position wherein the first wear contact (28) is away from the second wear contact (32) to avoid an electric arc between the first wear contact (28) and the second wear contact (32), an intermediate position wherein the first wear contact (28) is in electrical contact with the second wear contact (32), in particular via an electric arc, while the arm (26) and the second terminal (24) are still away from each other. to avoid an electric arc between the arm (26) and the second terminal (24), and the closed position, the first connection system (30) comprising a first flexible, electrically conductive member, the first flexible member having a proximal end secured to the arm (26) and a distal end secured to the first wear contact (28), the first flexible member being configured to allow the first wear contact (28) to be closer to the arm (26) in the closed position than in the intermediate position; and the second connection system (34) comprising a second flexible, electrically conductive, member (54), the second flexible member (54) having a proximal end (56) secured to the second terminal (24) and a distal end (58) secured to the second wear contact (32), the second flexible member (54) being configured to allow the second wear contact (32) to be closer to the second terminal (24) in the closed position than in the intermediate position; or the first connection system (30) comprising a first electrically conductive member having a proximal end secured to the arm (26) and a distal end secured to the first wear contact (28), the first member being configured to allow the first wear contact (28) to be closer to the arm (26) in the closed position than in the intermediate position, the first member and the first wear contact being formed in a single piece advantageously from a copper-tungsten alloy; and the second connection system (34) comprising a second electrically conductive member (54), the second member (54) having a proximal end (56) secured to the second terminal (24) and a distal end (58) secured to the second wear contact (32), the second member (54) being configured to allow the second wear contact (32) to be closer to the second terminal (24) in the closed position than in the intermediate position, the second member and the second wear contact being formed in a single piece advantageously from a copper-tungsten alloy.