Electromagnetic operating mechanism and vacuum switch

Abstract

This invention relates to an electromagnetic operating mechanism and a vacuum switch. A magnetic component is fixedly mounted on the push rod of the electromagnetic operating mechanism. The magnetic attraction of the permanent magnet to the magnetic component counteracts the closing self-closing force exerted by atmospheric pressure and the bellows inside the vacuum interrupter when the vacuum switch is opened, thus holding the moving contact in the open position. Furthermore, during closing, the magnetic attraction between the magnetic component and the permanent magnet is significantly reduced, allowing the electromagnetic operating mechanism to provide less kinetic energy to meet the closing requirements, mitigating contact system oscillations and ensuring the stability of contact opening and closing. Further, the permanent magnet is made movable; the magnetic attraction force of the permanent magnet on the magnetic component can be adjusted by changing the relative magnetic surface area of ​​the permanent magnet and the magnetic component. For vacuum switches of different specifications, the magnetic attraction force of the permanent magnet on the magnetic component can be adaptively adjusted so that the magnetic attraction force precisely meets the opening holding force requirement and also compensates for the inherent self-closing force tolerance of the vacuum interrupter.

Description

Technical Field

[0001] This invention relates to the field of switchgear, particularly to vacuum switches, and specifically to improvements in their electromagnetic operating mechanisms. Background Technology

[0002] Vacuum switches commonly employ electromagnetic operating mechanisms to drive the moving contact in the contact system. For example, Figure 1 The diagram illustrates the electromagnetic operating mechanism of a common vacuum switch, including an electromagnetic actuation mechanism 1, a push rod 2, and a return spring 3. The electromagnetic actuation mechanism 1 typically comprises an electromagnet and a moving iron core. Energizing the electromagnet generates a magnetic field, causing the moving iron core to move under the influence of the magnetic field. The moving iron core and the push rod 2 are fixedly connected. The push rod 2 is transmitted to the moving contact 4 via a connecting rod, achieving the closing movement of the moving contact 4 towards the stationary contact 5. The return spring 3 is used to drive the moving contact 4 to reset. Acting on the connecting rod, the return spring 3 deforms and stores energy during the closing process of the moving contact 4, thereby generating a driving force that opens the moving contact 4.

[0003] Unlike ordinary switches, the arc-extinguishing chamber of a vacuum switch is in a vacuum state. Due to the influence of external atmospheric pressure and the bellows inside the arc-extinguishing chamber, when the switch is opened, the moving contact 4 will be subjected to a self-closing force (i.e., automatic closing force) in the closing direction. Therefore, in order to keep the product in the open state, the reaction spring 3 must have a larger deformation during opening to resist this self-closing force with greater elasticity, forming an opening holding force on the moving contact 4. For example, in Figure 1 When the circuit is open, the reaction spring 3 (taking a tension spring as an example) is in a stretched state.

[0004] Therefore, when initiating closing from the open state, the electromagnetic actuation mechanism 1 needs to overcome the greater elastic force of the reaction spring 3. Furthermore, as the deformation of the reaction spring 3 gradually increases, its elastic force increases linearly. Thus, the electromagnetic actuation mechanism 1 needs to possess a large amount of kinetic energy to ensure the closing movement of the moving contact 4. For example, when the inventors were developing a PCB-based vacuum circuit breaker (rated voltage: 12kV; rated current: 40A) for use in data center power supply systems, they found that the driving power of the electromagnetic coil was relatively large, resulting in high power consumption.

[0005] Moreover, since the electromagnetic actuator 1 increases kinetic energy, it increases the system's energy under a fixed stroke. In addition to being converted into the elastic potential energy of the reaction spring 3 (since the closing stroke is fixed, that is, the deformation stroke of the reaction spring 3 is fixed, so the elastic potential energy stored by the reaction spring 3 during the closing process is also fixed) and the kinetic energy of the moving parts, the electromagnetic actuator 1 will generate excess energy. The excess energy is absorbed by the entire system, causing the system to oscillate and affecting the stability of the moving contact 4 during opening and closing. Summary of the Invention

[0006] Therefore, in order to address the above problems, this invention proposes an optimized electromagnetic operating mechanism and a vacuum switch.

[0007] This invention is achieved using the following technical solution:

[0008] This invention proposes an electromagnetic operating mechanism, including a fixed coil, a yoke, a movable iron core, and a push rod. The coil, in conjunction with the yoke, the movable iron core, and a reset spring, drives the push rod to extend or retract to achieve the closing or opening of a switch. It also includes a magnetic component and a permanent magnet. The magnetic component is fixedly mounted on the push rod, and the permanent magnet is located on the outside of the push rod and has a magnetic surface opposite to the magnetic component. When the push rod retracts, the magnetic attraction of the permanent magnet attracts the magnetic component, thereby holding the push rod in the retracted state. When the push rod extends, the magnetic gap between the magnetic component and the permanent magnet increases, significantly reducing the magnetic attraction of the permanent magnet on the magnetic component.

[0009] In order to adapt the magnetic attraction force of the permanent magnet to the magnetic component for vacuum switches of different specifications so that the magnetic attraction force can just meet the opening and holding force requirements, and in order to offset the objectively existing self-closing force tolerance of different vacuum interrupters, in one embodiment, the permanent magnet is preferably movable and has several movable positions at different locations, so that the area of ​​its relative magnetic surface with the magnetic component can be adjusted by moving the permanent magnet.

[0010] In one embodiment, based on installation and manufacturing considerations, the preferred electromagnetic operating mechanism further includes a mounting plate and a permanent magnet bracket. The mounting plate is fixedly installed, and the permanent magnet bracket is movably connected to the mounting plate, which can swing or move. The permanent magnet is fixedly connected to the permanent magnet bracket.

[0011] In order to subdivide the movement positions of the permanent magnet into smaller swing angles and make the adjustment of the magnetic attraction force of the permanent magnet more precise, in one embodiment, the mounting plate is preferably provided with a serrated slot, and the permanent magnet bracket includes a conical pin that fits in the slot. The pin is engaged with the serrations at different positions in the slot to realize the movement positions of the permanent magnet.

[0012] In order to improve the structural compactness and reduce the size of the electromagnetic operating mechanism, in one embodiment, the push rod preferably passes through the yoke, the magnetic component is a sleeve-shaped structure fixedly connected to the push rod, and two permanent magnets are provided on both sides of the push rod. The end of the sleeve-shaped magnetic component that is away from the yoke is turned outward to form a magnetic attraction part opposite to the permanent magnet, and a space is formed between the two permanent magnets for the end of the magnetic component that is closer to the yoke to be inserted.

[0013] In order to improve the adsorption effect of the magnetic component and thus enhance the opening and holding force, in one embodiment, the permanent magnet is preferably attached to the yoke, and when the push rod retracts, the end of the magnetic component that is relatively close to the yoke is also attached to the yoke.

[0014] In order to avoid the magnetic component and the permanent magnet from being attracted together and difficult to separate, in one embodiment, it is preferable that when the push rod is retracted, the magnetic attraction part and the permanent magnet maintain a certain magnetic gap.

[0015] In one embodiment, the preferred electromagnetic operating mechanism further includes a permanent magnet support for supporting the permanent magnet. The permanent magnet support is a hollow frame structure, and the permanent magnet is embedded and fixed in the permanent magnet support, so that one side of the permanent magnet can be attached to the yoke and the other side is opposite to the magnetic attraction part.

[0016] Based on the electromagnetic operating mechanism described above, this embodiment also proposes a vacuum switch, which includes the aforementioned electromagnetic operating mechanism.

[0017] To reduce the height of the vacuum switch and save installation space, the vacuum switch also includes a contact system. The contact system includes a moving contact and a stationary contact. The electromagnetic operating mechanism drives the moving contact to have a movement stroke relative to the stationary contact to achieve opening and closing. It also includes a transmission lever for transmitting and connecting the moving contact and the electromagnetic operating mechanism. With the movement stroke direction of the moving contact as the horizontal direction, the electromagnetic operating mechanism and the contact system are both arranged horizontally. The transmission lever is located on the same side of the electromagnetic operating mechanism and the contact system. The two ends of the transmission lever are respectively transmitted and connected to the electromagnetic operating mechanism and the moving contact, so that the electromagnetic operating mechanism, the transmission lever and the contact system are connected in a "[" shape.

[0018] The present invention has the following beneficial effects:

[0019] 1. The electromagnetic operating mechanism of the present invention uses the magnetic attraction of permanent magnets and magnetic components to counteract the self-closing force (including the force of air pressure and the force of bellows) on the moving contact in the open state, keeping the moving contact in the open position. Moreover, when closing, the magnetic attraction between the magnetic components and permanent magnets is greatly reduced, instead of the elastic force of the reaction spring increasing during the closing process as in the prior art. Therefore, the electromagnetic operating mechanism does not need to provide too much closing kinetic energy, only enough to meet the closing start requirement. With the reduction of kinetic energy provided by the electromagnetic operating mechanism, the oscillation of the contact system is alleviated, ensuring the stability of the contact opening and closing.

[0020] 2. The permanent magnet of this invention is movable. By adjusting the area of ​​the relative magnetic surfaces of the permanent magnet and the magnetic component, the magnetic attraction force of the permanent magnet on the magnetic component can be adjusted. For vacuum switches of different specifications, the magnetic attraction force of the permanent magnet on the magnetic component can be adaptively adjusted so that the magnetic attraction force can just meet the opening and holding force requirements, thereby meeting the needs of different actual products, and at the same time, it can also offset the objectively existing self-closing force tolerance of different vacuum interrupters. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the electromagnetic operating mechanism of a vacuum switch in the prior art;

[0022] Figure 2 This is an exploded view of the vacuum switch in the embodiment;

[0023] Figure 3 This is a three-dimensional schematic diagram of the electromagnetic operating mechanism, transmission lever, and contact system of the vacuum switch in the embodiment.

[0024] Figure 4 This is a three-dimensional schematic diagram of the electromagnetic operating mechanism in the embodiment;

[0025] Figure 5 This is an exploded view of the electromagnetic operating mechanism in the embodiment;

[0026] Figure 6 This is a front view of the electromagnetic operating mechanism in the embodiment;

[0027] Figure 7 yes Figure 6 Sectional view at point AA;

[0028] Figure 8 yes Figure 6 Sectional view at point BB;

[0029] Figure 9 yes Figure 7 A magnified view of a section at point M;

[0030] Figure 10 This is a schematic diagram of the permanent magnet, permanent magnet support, and mounting plate in the embodiment. Detailed Implementation

[0031] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0032] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0033] See Figure 2-3 As shown, in a preferred embodiment of the present invention, a vacuum switch is provided. The vacuum switch includes a housing, a circuit board, an electromagnetic operating mechanism 1, a transmission lever 2, and a contact system 3. The contact system 3 includes a stationary contact, a moving contact, and a vacuum interrupter. The middle section of the transmission lever 2 is hinged and limited. The two ends of the transmission lever 2 are respectively hinged to the electromagnetic operating mechanism 1 and the moving contact in the contact system 3. The electromagnetic operating mechanism 1 generates power and transmits it to the moving contact through the transmission lever 2, so that the moving contact has a stroke in the T1-T2 direction to achieve contact or separation with the stationary contact, thereby completing the opening and closing of the moving and stationary contacts in the contact system 3. In this embodiment, the T1-T2 direction is defined as the horizontal direction. In a typical vacuum switch structure, the contact system is usually arranged horizontally, while the electromagnetic operating mechanism is arranged vertically. The electromagnetic operating mechanism and the contact system are connected by a linkage mechanism. In this embodiment, both the electromagnetic operating mechanism 1 and the contact system 3 are arranged horizontally. The electromagnetic operating mechanism 1 and the contact system 3 are connected by a transmission lever 2, so that the electromagnetic operating mechanism 1, the transmission lever 2 and the contact system 3 are connected in a "[" shape. This makes the vacuum switch structure compact. Especially in applications where the electromagnetic operating mechanism 1 and the contact system 3 are arranged one above the other in the direction of gravity, the height of the vacuum switch can be reduced, saving installation space.

[0034] Among them, such as Figure 4-5 The electromagnetic operating mechanism 1 specifically includes a support plate 10, a coil 11, a yoke 13, and a moving iron core 19. The coil 11 and the yoke 13 are fixedly mounted on the support plate 10, and the moving iron core 19 passes through the coil. The coil 11, the yoke 13, and the moving iron core 19 form an electromagnetic actuation mechanism. When the coil 11 is energized, a magnetic field is generated. The yoke 13 closes the magnetic circuit to increase the magnetic attraction force, attracting the moving iron core 19 to move. (See also...) Figure 7 and Figure 3-4 The push rod 18 passes through the yoke 13 and is slidably mounted at one end of the moving iron core 19. The end of the push rod 18 extending out of the yoke 13 is hinged to the transmission lever 2. When the moving iron core 19 moves toward the yoke 13, it pushes the push rod 18 outward (in the direction of T1). Then, through the transmission lever 2, the moving contact in the contact system 3 approaches the stationary contact and finally closes the circuit. The electromagnetic operating mechanism 1 also includes a compression spring 12. The two ends of the compression spring 12 act on the push rod 18 and the yoke 13 respectively. When the push rod 18 extends outward to complete its closing stroke, the compression spring 12 is compressed to generate elastic force. After the coil 11 is de-energized, the compression spring 12 releases its energy and drives the push rod 18 to retract (in the direction of T2 in the figure). The push rod 18 pushes the moving iron core 19 back to its original position. When the push rod 18 retracts, through the transmission lever 2, the moving contact in the contact system 3 separates from the stationary contact and finally opens the circuit.

[0035] Specifically, to resist the self-closing force in the closing direction experienced by the moving contact under atmospheric pressure and the action of the bellows in the vacuum interrupter when the vacuum switch is opened, the electromagnetic operating mechanism 1 also includes a closing holding unit, such as... Figure 5 as well as Figure 7-9 As shown, the trip holding unit includes a permanent magnet 15 and a magnetic component 17. The magnetic component 17 is made of a material that can be attracted by the magnetic force of the permanent magnet, such as a magnetically affinity metal like iron, nickel, or cobalt, or a composite thereof. The magnetic component 17 is a tubular structure that is inserted and fixed to the push rod 18. The permanent magnet 15 is located on the outside of the push rod 18 and has a portion of its magnetic surface facing the magnetic component 17. When the push rod 18 retracts, the magnetic force of the permanent magnet 15 attracts the magnetic component 17, thereby holding the push rod 18 in the retracted state. When the push rod 18 extends to close the circuit, the magnetic gap between the magnetic component 17 and the permanent magnet 15 increases, thus significantly reducing the magnetic force of the permanent magnet 15 on the magnetic component 17. This solution not only counteracts the closing self-closing force during opening by using magnetic attraction to keep the moving contact in the open position, but also significantly reduces the magnetic attraction between the magnetic component 17 and the permanent magnet 15 during closing, unlike the existing technology where the elastic force of the reaction spring increases during closing. Therefore, the electromagnetic operating mechanism 1 in this solution does not need to provide too much closing kinetic energy, only enough to meet the closing start requirements. With the reduced kinetic energy provided by the electromagnetic operating mechanism 1, the oscillation of the contact system is alleviated, ensuring the stability of contact opening and closing.

[0036] In this embodiment, the magnetic component 17 is fixed by a plug-in connection. In other embodiments, other fixing methods such as screws or clips can also be used.

[0037] like Figure 7 and Figure 9 As shown, two permanent magnets 15 are provided on both sides of the push rod 18. A sleeve-shaped magnetic element 17 has its end facing outwards to form a magnetic attraction part 171, located away from the yoke 13. A space is formed between the two permanent magnets 15 for the end of the magnetic element 17 closest to the yoke 13 to be inserted. When the push rod 18 retracts, the magnetic attraction part 171 and the permanent magnets 15 interact to achieve magnetic attraction of the permanent magnets 15 to the magnetic element 17. The end of the magnetic element 17 closest to the yoke 13 is inserted between the two permanent magnets 15, resulting in a very compact fit between the permanent magnets 15 and the magnetic element 17, which helps to reduce the overall size of the electromagnetic operating mechanism. Providing two permanent magnets 15 on both sides of the push rod 18 also helps to balance the attraction force on the magnetic element 17.

[0038] Moreover, in this embodiment, the permanent magnet 15 is attached to the yoke 13. When the push rod 18 retracts, the end of the magnetic component 17 that is relatively close to the yoke 13 also abuts against the yoke 13. Thus, by utilizing the magnetic conduction effect of the yoke 13, the magnetic component 17 is further attracted to the yoke 13, ensuring that the moving contact can remain in the open position under the influence of the closing self-closing force.

[0039] Meanwhile, when the magnetic component 17 is attracted to the yoke 13, the permanent magnet 15 and the magnetic component 17 maintain a certain magnetic gap, preventing them from attracting each other. If they were attracted together, the push rod 18 would need a large closing kinetic energy to push them apart. This embodiment, through the above arrangement, ensures that the magnetic force of the permanent magnet 15 creates a certain opening holding force on the magnetic component 17, while preventing the opening holding force from becoming too large and affecting the closing process.

[0040] Of course, in other embodiments, other magnetic components can also be used. As long as the magnetic component is fixed on the push rod 18 and can be attracted by the permanent magnet 15 and retracted, it is a feasible solution. For example, a sheet-like magnetic component extending radially in the push rod 18 can be used.

[0041] The permanent magnet 15 is installed in the following manner: (See attached document) Figure 4 , 58, 10. A mounting plate 16 is fixedly connected to the yoke 13. Two permanent magnet supports 14 are movably connected to the mounting plate 16. Specifically, the permanent magnet supports 14 are provided with inserts 141, and the mounting plate 16 is provided with insertion holes 161 that mate with the inserts 141. The inserts 141 are inserted into the insertion holes 161 to achieve the movable connection between the permanent magnet supports 14 and the mounting plate 16. The permanent magnet supports 14 are hollow frame structures. Rectangular permanent magnets 15 are embedded and fixed inside the permanent magnet supports 14, so that one side of the permanent magnets 15 can be attached to the yoke 13, and the other side faces the magnetic attraction part 171. Because the permanent magnet supports 14 are movable, that is, the permanent magnets 15 are movable, the position of the permanent magnets 15 can be adjusted by moving the permanent magnet supports 14, thereby adjusting the relative magnetic surface area of ​​the permanent magnets 15 and the magnetic component 17, and thus adjusting the magnetic attraction force of the permanent magnets 15 on the magnetic component 17. Clearly, the magnetic attraction force of the permanent magnet 15 to the magnetic component 17 is not necessarily better the greater it is. While ensuring the magnetic attraction force meets the required opening and holding force, a greater magnetic attraction force results in greater resistance during closing. Therefore, the magnetic attraction force of the permanent magnet 15 to the magnetic component 17 should just meet the opening and holding force requirement. Different specifications of vacuum switches will have different opening and holding force requirements. Using the electromagnetic drive mechanism 1 of this embodiment, due to the adjustable nature of the permanent magnet 15, the magnetic attraction force of the permanent magnet 15 to the magnetic component 17 can be adaptively adjusted to meet different actual product requirements. Furthermore, since the closing self-closing force (including atmospheric pressure and bellows force) objectively has an inherent tolerance of ±5N, it is necessary to adjust the magnetic attraction force of the permanent magnet 15 to the magnetic component 17 to offset the influence of this tolerance on the product's opening and closing process. This minimizes the inconsistency in the product's opening and closing characteristics caused by the different closing self-closing forces of each vacuum interrupter.

[0042] In other embodiments, besides using a swingable method to connect the permanent magnet bracket 14 to the mounting plate 16, other movable connection methods can also be used, such as sliding the permanent magnet bracket 14 to the mounting plate 16. In addition to the embedded fixing method, other embodiments can also use other methods to fix the permanent magnet 15, such as screwing, bonding, etc.

[0043] The mounting plate 16 also has serrated slots 162. The permanent magnet bracket 14 includes a conical pin 142 that fits into the slot 162. The pin 142 engages with the serrations at different positions within the slot 162, allowing the permanent magnet 15 to have multiple movable positions. Alternatively, other methods can be used to achieve multiple movable positions for the permanent magnet 15. For example, a pressable steel ball can be provided on the permanent magnet bracket 14, tensioned by a spring. When the ball is pressed, it springs back to its original position. Multiple ball slots can be created on the mounting plate 16, and moving the permanent magnet bracket 14 allows the steel ball to engage in different slots, thus achieving multiple movable positions for the permanent magnet 15. This embodiment uses the combination of serrated slots and conical pins to subdivide the movable positions of the permanent magnet 15 within a smaller swing angle, making the adjustment of the magnetic force of the permanent magnet 15 more precise.

[0044] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail made to the invention without departing from the spirit and scope of the invention as defined in the appended claims fall within the protection scope of the invention.

Claims

1. An electromagnetic operating mechanism, comprising a fixedly mounted coil, a yoke, a movable iron core, and a push rod, wherein the coil, in conjunction with the yoke, the movable iron core, and a reset spring, drives the push rod to extend or retract to achieve the closing or opening of a vacuum switch, characterized in that: It also includes a magnetic component and a permanent magnet. The magnetic component is fixedly mounted on the push rod, and the permanent magnet is disposed on the outside of the push rod and has a magnetic surface opposite to the magnetic component. When the push rod retracts, the magnetic component is attracted by the magnetic attraction of the permanent magnet, thereby keeping the push rod in the retracted state. When the push rod extends, the magnetic air gap between the magnetic component and the permanent magnet increases, thereby significantly reducing the magnetic attraction of the permanent magnet on the magnetic component. The permanent magnet is movable, and its relative magnetic surface area with the magnetic component can be adjusted by moving the permanent magnet.

2. The electromagnetic operating mechanism according to claim 1, characterized in that: The permanent magnet has several movable positions at different locations.

3. The electromagnetic operating mechanism according to claim 2, characterized in that: It also includes a mounting plate and a permanent magnet bracket, wherein the mounting plate is fixedly installed, the permanent magnet bracket is movably connected to the mounting plate, and the permanent magnet is fixedly connected to the permanent magnet bracket.

4. The electromagnetic operating mechanism according to claim 3, characterized in that: The mounting plate has a serrated slot, and the permanent magnet bracket includes a conical pin that fits in the slot. The pin engages with the serrations at different positions in the slot to achieve the movable position of the permanent magnet.

5. The electromagnetic operating mechanism according to claim 1 or 2, characterized in that: The push rod passes through the yoke. The magnetic component is a sleeve-shaped structure that is fixedly connected to the push rod. There are two permanent magnets on both sides of the push rod. The end of the magnetic component of the sleeve-shaped structure that is far away from the yoke is turned outward to form a magnetic attraction part opposite to the permanent magnet. A space is formed between the two permanent magnets for the end of the magnetic component that is close to the yoke to be inserted.

6. The electromagnetic operating mechanism according to claim 5, characterized in that: The permanent magnet is attached to the yoke, and when the push rod retracts, the end of the magnetic component that is relatively close to the yoke is also attached to the yoke.

7. The electromagnetic operating mechanism according to claim 6, characterized in that: When the push rod retracts, the magnetic suction part and the permanent magnet maintain a certain magnetic gap.

8. The electromagnetic operating mechanism according to claim 6, characterized in that: It also includes a permanent magnet support for supporting the permanent magnet. The permanent magnet support is a hollow frame structure. The permanent magnet is embedded and fixed in the permanent magnet support, so that one side of the permanent magnet can be attached to the yoke and the other side is opposite to the magnetic attraction part.

9. A vacuum switch, including an electromagnetic operating mechanism for driving it to open or close, characterized in that: The electromagnetic operating mechanism is the electromagnetic operating mechanism as described in any one of claims 1-8.

10. The vacuum switch according to claim 9, characterized in that: It also includes a contact system comprising a moving contact and a stationary contact. The electromagnetic operating mechanism drives the moving contact to have a travel relative to the stationary contact to achieve opening or closing. It also includes a transmission lever for connecting the moving contact and the electromagnetic operating mechanism. With the travel direction of the moving contact as the horizontal direction, the electromagnetic operating mechanism and the contact system are both arranged horizontally. The transmission lever is located on the same side of the electromagnetic operating mechanism and the contact system. Both ends of the transmission lever are respectively connected to the electromagnetic operating mechanism and the moving contact, so that the electromagnetic operating mechanism, the transmission lever and the contact system are connected in a "[" shape.

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