FR3104806A1 - Electrical switch with wear contacts - Google Patents

Abstract

Electrical switch with wear contacts Electrical switch (18) comprising: - a first terminal (22) and a second terminal (24) suitable for being electrically connected to a first electrical circuit (14) and to a second electrical circuit (16) , and - an arm (26) electrically connected to the first terminal (22), and movable relative to the second terminal (24) between a closed position of the switch and an open position of the switch. The switch comprises a first wear contact (28) and a second wear contact (32) electrically and mechanically connected respectively to the arm by a first connection system (30), and to the second terminal by a second connection system (34). The arm is successively movable between the open position, in which the first wear contact is away from the second wear contact to avoid an electric arc between the first wear contact and the second wear contact , an intermediate position, in which the first wear contact is in electrical contact with the second wear contact, in particular via an electric arc, while the arm and the second terminal are still away from one another. 'other to avoid an electric arc between the arm and the second terminal, and the closed position. Figure for abstract: Figure 2

Description

Electrical switch with wear contacts

The present invention relates to an electrical switch comprising:

- a first terminal and a second terminal able to be respectively electrically connected to a first electrical circuit and to a second electrical circuit, 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 together, and an open position of the switch , wherein the arm is away from the second terminal.

The invention also relates to a vehicle, in particular a rail vehicle, comprising at least one such switch.

The invention also relates to a method of manufacturing such a switch, the manufacture being an initial manufacture or a retrofit to obtain the switch.

Such a switch is suitable for supplying electricity to vehicles, in particular railway vehicles, that is to say at voltages of the order of 15,000 V to 25,000 V. At such voltages, the opening or closing of 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 material removal and/or damage to the arm and to the second terminal.

This can alter the operation of the switch, and in any event reduces its life.

Thus, an object of the invention is to propose a switch of the type described above offering an improved service life, all other things being equal.

To this end, the subject of the invention is a switch of the type described above, in which:

- the switch further comprises a first wear contact and a second wear contact electrically and mechanically connected respectively to the arm and to the second terminal, respectively by a first connection system and by a second connection system, and

- the arm is movable successively between the open position in which the first wear contact is away from the second wear contact to avoid an electric arc between the first wear contact and the second wear contact , an intermediate position in which the first wear contact is in electrical contact with the second wear contact, in particular via an electric arc, while the arm and the second terminal are still away from one another other to avoid an electric arc between the arm and the second terminal, and the closed position. According to particular embodiments, the switch comprises one or more of the following characteristics, taken separately or according to all the technically possible combinations:

- the first connection system and the second connection system are adapted so that the first wear contact and the second wear contact remain in electrical contact during passage of the arm from the intermediate position to the closed position;

- the first connection system and the second connection system are adapted so that the first wear contact and the second wear contact remain in electrical contact during passage of the arm from the closed position to the intermediate position;

- the first connection system comprises a first flexible, electrically conductive member, the first flexible member having a proximal end fixed to the arm and a distal end fixed to the first wear contact, the first flexible member being configured to allow the first wear contact (to be closer to the arm in the closed position than in the intermediate position; and/or the second connection system comprises a second flexible, electrically conductive member, the second flexible member having a proximal end fixed to the second terminal and a distal end attached to the second wear contact, the second flexible member being configured to allow the second wear contact to be closer to the second terminal in the closed position than in the intermediate position;

- the first connection system comprises a first electrically conductive member having a proximal end fixed to the arm and a distal end fixed to the first wear contact, the first member being configured to allow the first wear contact to be more closer to the arm in the closed position than in the intermediate position, the first member and the first wear contact being formed in one piece, advantageously from a copper-tungsten alloy; and/or the second connection system comprises a second electrically conductive member, the second member having a proximal end fixed to the second terminal and a distal end fixed to the second wear contact, the second member being configured to allow the second wear contact to be closer to the second terminal in the closed position than in the intermediate position, the second member and the second wear contact being formed in one piece, advantageously from a copper-tungsten alloy;

- the first connection system comprises a rigid member, electrically conductive, carrying the first wear contact, the rigid member being rotatably mounted on the arm about a pivot axis between a position at rest, and a position compressed, in which the first wear contact is closer to the arm than in the rest position, the first connection system further comprising a return member adapted to elastically return the rigid member from the compressed position to the rest; And

- the electrical switch further comprises a support, and in which the first terminal comprises an electrically insulating part rotatably mounted on the support around the axis of rotation, and an electrically conductive part on which the arm is fixed and adapted to be connected to the first electrical circuit.

The invention also relates to a vehicle, in particular a rail vehicle, comprising at least one switch as described above, a first electrical circuit connected to the first terminal, and a second electrical circuit connected to the second terminal.

According to a particular embodiment, the switch is located in or on the roof.

Finally, the subject of the invention is a method for manufacturing an electrical switch comprising the following steps:

- supply of a first terminal and a second terminal capable of being respectively electrically connected to a first electrical circuit and to a second electrical circuit,

- provision of 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 a position of opening of the switch, in which the arm is away from the second terminal,

- provision of a first wear contact and a second wear contact, and

- connection of the first wear contact and of the second wear contact electrically and mechanically respectively to the arm and to the second terminal, respectively by a first connection system and by a second connection system, the arm being movable successively between the position opening in which the first wear contact is away from the second wear contact to avoid an electric arc between the first wear contact and the second wear contact, an intermediate position in which the first contact wear contact is in electrical contact with the second wear contact, in particular via an electric arc, while the arm and the second terminal are still away from each other to avoid an electric arc between the arm and the second terminal, and the closed position.

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:

FIG. 1 is a schematic view of the roof of a vehicle according to the invention, comprising a switch according to the invention, represented in perspective, certain elements of the switch being omitted, and the arm being in the open position of the switch ,

Figure 2 is a schematic view, from above, of the vehicle shown in Figure 1, the arm having almost arrived in the intermediate position,

Figure 3 is a schematic top view of the switch shown in Figures 1 and 2, the arm being in the closed position of the switch,

FIG. 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 FIGS. 1 to 3, and

Figure 5 is a partial top view of a switch constituting a variant of the switches shown in Figures 1 to 4.

With reference to Figures 1 to 3, a vehicle 10 according to the invention is described. In the example shown, the vehicle 10 is a railway vehicle electrically supplied with high voltage by systems not shown. By "high voltage" is meant for example a voltage greater than or equal to 10 kV, advantageously about 25 kV.

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

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

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.

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

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 electric power to several electric sub-circuits from the first electric circuit 14 or else from another electric circuit.

The switch 18 comprises a support 20 fixed on or in the roof 12, a first terminal 22 electrically connected to the first electric circuit 14, and a second terminal 24 electrically connected to the second electric circuit 16. The switch 18 also comprises an arm 26 electrically connected to the first terminal 22, and rotatable around an axis D1 relative to the second terminal 24 between a closed position of the switch (shown in Figure 3), an open position (shown in Figure 1) , and different intermediate positions (one of which is shown in Figure 2).

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.

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.

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

By "insulator" is meant that the element is not suitable for conducting electricity and has for example a resistivity greater than 10 ⁵ Ω.m.

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.

The first wear contact 28 and the second wear contact 32 are advantageously similar to each other structurally. They form for example two plates, and are advantageously made of an alloy of silver and/or tungsten

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.

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 Figure 2, in order to allow the appearance of an arc electric 46 between them, the arm 26 and the second terminal 24 being far enough apart 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.

The dimensions of the connection systems 30 and 34 are chosen according to the voltage present between the terminals 22 and 24. Care will be taken to ensure that the intermediate position corresponds to the priming position, that is to say 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 booting.

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 in FIG. 2, the wear contacts 28, 32 are in contact with each other.

In the example shown, the contact is flat for greater ease of construction.

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

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). 'other or are electrically connected to each other via an electric arc) to the closed position, the contact preferably remaining plane.

In the example shown, the first connection system 30 and the second connection system 34 are structurally similar to each other.

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

“Conductive” means that the element is suitable ^{for conducting electricity, its resistivity being for example less than 10-7 Ω.m.}

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 Figure 2.

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

The second flexible member 54, in the example shown, has a proximal end 56 fixed to the second terminal 24, and a distal end 58 fixed 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 Figure 2.

According to a particular embodiment, the first flexible member 48 and the second flexible member 54 are made in one piece respectively with the first wear contact 28 and the second wear contact 32. For example, the assemblies thus formed comprise a material conductive and resistant to the electric arc 46, for example a copper-tungsten alloy. These sets are advantageously made of this alloy.

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

The open position (FIG. 1) makes it possible to electrically isolate the first electric circuit 14 from the second electric 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.

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 causes the arm 26 to rotate towards the second terminal 24. This also has the effect of bringing the wear contacts 28, 32 from each other.

When the arm 26 reaches the intermediate position shown in 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.

Then, the arm 26 still approaching the second 24, the wear contacts 28, 32 come into contact with each other. Finally, the arm 26 reaches the closed position shown in 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 until the closed position, the wear contacts remain in electrical contact with each other, which prevents the appearance 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.

Conversely, to open the switch 18, the arm 26 is driven in rotation 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 appearance of an electric arc between the arm and the second terminal.

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 distant from each other.

Then, the electric arc 46 ceases when the wear contacts 28, 32 are in turn sufficiently distant from each other. The arm 26 arrives shortly after in the open position (Figure 1).

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

The method includes providing the first terminal 22 and the second terminal 24, and the arm 26.

The method further comprises providing the first wear contact 28 and the second wear contact 32, and their electrical and mechanical connection, respectively to the arm 26 and to the second terminal 24, respectively by the first connection system 30 and the second connection system 34.

This is an initial production 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.

According to a variant, the manufacturing process is a retrofit or improvement process 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 that the steps of providing the wear contacts 28, 32 and the connection systems 30, 34 are carried out some time afterwards to improve the switch.

This is for example done as shown in Figure 4.

The first wear contact 28 is for example supplied already fixed on the first flexible member 48. The distal end 50 is then easily fixed on the arm 26, for example using a clip 60.

Advantageously, the attachment 60 is adapted to allow an 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 with respect to the second terminal 24 from which the wear contacts 28, 32 come into electrical and/or physical contact with one another. with each other when closing, or separate from each other when opening.

Thanks to the characteristics described above, the wear of the arm 26 and the jaws 42 is reduced and the switch 18 has an improved life.

Referring to Figure 5, we will now describe a switch 118 (partially shown) constituting a variant of the switch 18. The switch 118 is similar to the switch 18 shown in Figures 1 to 3. Similar elements bear the same reference numerals and will not be described again. Only the differences will be described in detail below.

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

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

The rigid member 148 is electrically conductive and carries the first wear contact 28. The rigid member is rotatably mounted on the arm 26 around a pivot axis D3, between a position at rest (shown in FIG. 5), and a compressed position (not shown but deduced from the position at rest 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.

The rigid member 148 is for example a straight rod or blade.

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

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.

In this variant, the connection system of the second wear contact 32 is for example similar to the connection system 130.

According to other variants not shown, only one of the connection systems 30, 34 has flexibility. In fact, to dampen 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 (10)

Electrical switch (18; 118) comprising:
- a first terminal (22) and a second terminal (24) able to be respectively electrically connected to a first electrical circuit (14) and to a second electrical circuit (16), and
- an arm (26) electrically connected to the first terminal (22), and movable relative to the second terminal (24) between a closed position of the switch (18; 118), in which the arm (26) electrically connects the first terminal (22) and the second terminal (24) between them, and an open position of the switch (18; 118), in which 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 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), and
- the arm (26) is movable successively between the open position in which the first wear contact (28) is away from the second wear contact (32) to avoid an electric arc between the first contact d wear contact (28) and the second wear contact (32), an intermediate position in which 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 position closing. Electrical switch (18; 118) according to claim 1, in which the first connection system (30; 130) and the second connection system (34) are adapted so that the first wear contact (28) and the second contact wear (32) remain in electrical contact during passage of the arm (26) from the intermediate position to the closed position. Electrical switch (18; 118) according to claim 1 or 2, in which 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 during passage of the arm (26) from the closed position to the intermediate position. An electrical switch (18; 118) according to any preceding claim, wherein:
- the first connection system (30) comprises a first flexible, electrically conductive member, the first flexible member having a proximal end fixed to the arm (26) and a distal end fixed 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/or
- the second connection system (34) comprises a second flexible member (54), electrically conductive, the second flexible member (54) having a proximal end (56) fixed 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. An electrical switch (118) according to any of claims 1 to 3, wherein:
- the first connection system (30) comprises a first electrically conductive member having a proximal end fixed to the arm (26) and a distal end fixed 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 one piece, advantageously in an alloy copper-tungsten, and/or
- the second connection system (34) comprises a second electrically conductive member (54), the second member (54) having a proximal end (56) fixed to the second terminal (24) and a distal end (58) fixed 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 closed position intermediary, the second member and the second wear contact being formed in one piece, advantageously in a copper-tungsten alloy. Electrical switch (118) according to any one of Claims 1 to 5, in which the first connection system (130) comprises a rigid, electrically conductive member (148) carrying the first wear contact (28), the rigid member (148) being rotatably mounted on the arm (26) about a pivot axis (D3) between a rest position and a compressed position, in which the first wear contact (28) is more closer to the arm (26) than in the rest position, the first connection system (130) further comprising a return member (150) adapted to elastically return the rigid member (148) from the compressed position to the position of rest. An electrical switch (18; 118) according to any one of claims 1 to 6, further comprising a support (20), and wherein the first terminal (22) comprises an electrically insulating portion (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 able to be connected to the first electrical circuit (14). Vehicle (10), in particular railway, comprising at least one switch (18; 118) according to any one of Claims 1 to 7, a first electric circuit (14) connected to the first terminal (22), and a second electric circuit (16) connected to the second terminal (24). A vehicle (10) according to claim 8, further comprising a roof (12), and wherein said switch (18; 118) is located in or on the roof (12). Method of manufacturing an electrical switch (18; 118), comprising the following steps:
- provision of a first terminal (22) and a second terminal (24) adapted to be respectively electrically connected to a first electric circuit (14) and to a second electric circuit (16), and
- provision of an arm (26) electrically connected to the first terminal (22), and movable relative to the second terminal (24) between a closed position of the switch (18; 118), in which the arm (26) electrically connects the first terminal (22) and the second terminal (24) to each other, and an open position of the switch (18; 118), in which the arm (26) is away from the second terminal (24 ),
characterized in that it further comprises the following steps:
- providing a first wear contact (28) and a second wear contact (32), and
- connection of the first wear contact (28) and the second wear contact (32) electrically and mechanically 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 in which 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 in which the first wear contact (28) is in electrical contact with the second contact d wear (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.