An electromagnetic switch

Abstract

The invention provides an electromagnetic switch, comprising: a shell, an electromagnetic assembly, a contact mechanism and an armature, wherein the shell is provided with two spring buttons connected in parallel, and a first spring button is provided with a kick structure inside thereof for providing resistance at the initial stage of pressing the first spring button; the electromagnetic switch of the invention is provided with a kick structure on the spring button above the electromagnetic assembly, and when the force of pressing the button is insufficient, the spring button cannot move downward, thereby not causing the electromagnetic assembly to generate a suction force, and not causing the contact to be in a state of being neither on nor off; the button can only be moved downward when the force of pressing the button is sufficient to overcome the resistance of the kick structure, and once the button breaks through the resistance of the kick structure, the kick structure will no longer generate resistance to the button, and at this time, due to the effect of inertia, the spring button can be quickly pressed to the bottom at one time, thereby causing the contact to be connected, and effectively avoiding the generation of arcing.

Description

Technical Field

[0001] The present invention relates to the technical field of switches, and in particular to an electromagnetic switch. Background Art

[0002] An electromagnetic switch refers to a switch controlled by an electromagnet. When the electromagnet coil is energized, electromagnetic attraction is generated, and the movable iron core pushes or pulls the switch contacts to close, thereby connecting the controlled circuit.

[0003] When the electromagnetic switch is applied to the switch of the power tool, the electromagnetic switch is generally used to maintain the switch on position, and the action of connecting the circuit is still performed by manual pressing. When operating the switch, before the circuit is connected by manual pressing, the electromagnetic coil is not energized, and there is no electromagnetic force at this time. Therefore, in order to ensure that the circuit can be connected quickly, the switch needs to be pressed quickly and in place at once.

[0004] However, in actual operation, due to the operating habits of personnel, the switch is often not pressed into place quickly and at once, which easily causes the electrical contact to be in a state of being neither on nor off, which easily generates arcing and thus easily burns the contact mechanism. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of the electromagnetic switch in the prior art that it is easy to fail to be pressed into place at one time, thereby providing an electromagnetic switch that can ensure that it can be pressed into place at one time when used.

[0006] In order to solve the above technical problems, the present invention provides an electromagnetic switch, comprising:

[0007] The housing has two spring buttons connected in parallel;

[0008] An electromagnetic assembly, disposed in the housing and opposite to the first spring button;

[0009] A contact mechanism, disposed in the housing and opposite to the second spring button;

[0010] An armature is rotatably connected to the interior of the housing, with one end extending to one side of the first spring button and the other end extending to one side of the second spring button;

[0011] A kick structure is provided inside the first spring button for providing resistance at the beginning of pressing the first spring button.

[0012] As a preferred solution, the sudden jump structure includes:

[0013] A blocking member, which is laterally connected to the inside of the push rod of the first spring button through a spring, and has an arc-shaped structure protruding from the push rod;

[0014] The boss is arranged on the sliding path of the push rod and is suitable for contacting with the arc structure of the blocking member.

[0015] As a preferred solution, the blocking member is spherical or conical.

[0016] As a preferred solution, there are a plurality of blocking members on the push rod.

[0017] As a preferred solution, a plurality of blocking members are evenly arranged on the push rod along the circumferential direction.

[0018] As a preferred solution, the contact mechanism includes:

[0019] A stationary contact group, fixedly arranged in the housing;

[0020] A moving contact frame is connected in the housing so as to slide up and down relative to the stationary contact group, and is elastically connected with the moving contact group inside;

[0021] The first elastic member is connected between the movable contact frame and the housing, and has a biasing force for moving the movable contact frame in a direction away from the second spring button.

[0022] As a preferred solution, the moving contact group includes:

[0023] The first moving contact group is elastically connected to the moving contact frame via a second elastic member;

[0024] The second moving contact group is elastically connected to the moving contact frame via a third elastic member;

[0025] The first moving contact group and the second moving contact group are electrically connected.

[0026] As a preferred solution, the static contact group includes:

[0027] a first static contact group, opposite to a first moving contact group of the moving contact group;

[0028] a second static contact group, opposite to the second moving contact group of the moving contact group;

[0029] The brake static contact group is arranged on the other side of the first moving contact group away from the first static contact group, and shares the same first moving contact group with the first static contact group.

[0030] As a preferred solution, the first moving contact group, the first static contact group and the brake static contact group all have two symmetrical electrical contacts.

[0031] As a preferred solution, the two electrical contacts of the brake static contact group are used to be electrically connected to the two wiring terminals of the drive motor respectively.

[0032] The technical solution of the present invention has the following advantages:

[0033] 1. The electromagnetic switch provided by the present invention is provided with a jump structure on the spring button above the electromagnetic component. When the button is pressed down with insufficient force, the spring button cannot move downward, thereby not causing the electromagnetic component to generate an attraction force and not causing the contact to be in a state of being neither on nor off. The button can only be moved downward when the button is pressed down with sufficient force to overcome the resistance of the jump structure, and once the button breaks through the resistance of the jump structure, the jump structure will no longer generate resistance to the button. At this time, due to the effect of inertia, the spring button can be quickly pressed to the bottom at one time, thereby connecting the contacts, effectively avoiding the arcing phenomenon and increasing the service life of the electromagnetic switch.

[0034] 2. The electromagnetic switch provided by the present invention blocks the push rod on the spring button through the structure of the boss and the blocking member, so that when the push rod overcomes the resistance of the boss and the blocking member structure, the resistance disappears, so that the push rod maintains a large inertia during the movement of the subsequent moving section.

[0035] 3. The electromagnetic switch provided by the present invention can keep the push rod vertical during movement and is not prone to deviation by evenly arranging multiple blocking members on the push rod.

[0036] 4. The electromagnetic switch provided by the present invention has a brake contact group, and the brake static contact group and the first static contact group share a moving contact group. This design can save the number of moving contact groups and reduce the volume of the contact mechanism.

[0037] 5. In the electromagnetic switch provided by the present invention, the two electrical contacts of the brake contact group are used to be electrically connected to the two wiring terminals of the driving motor respectively. When the driving motor finishes running, its connection with the power supply is disconnected. However, at this time, the self-rotation of the motor will generate a large instantaneous armature current. The two electrical contacts of the brake contact group are electrically connected through the contact between the moving contact group and the brake contact group, so that the wiring terminals at both ends of the motor can be short-circuited, thereby preventing the motor from continuing to rotate due to inertia and generating a large armature current, thereby protecting the contacts of the switch from being burned out. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 It is a front view and cross-sectional view of an embodiment of the electromagnetic switch of the present invention.

[0040] Figure 2 for Figure 1 Magnified view of area A.

[0041] Figure 3 for Figure 1 Magnified view of area B.

[0042] Figure 4 for Figure 3 Middle CC section view.

[0043] Figure 5 for Figure 3 Middle DD section view.

[0044] Figure 6 for Figure 1 Schematic diagram after the first spring button is pressed.

[0045] Figure 7 for Figure 6 Magnified view of area E in the middle.

[0046] Figure 8 for Figure 6 Schematic diagram of the first spring button after it pops up.

[0047] Fig. 9 for Figure 8 Schematic diagram of the second spring button after being pressed.

[0048] Fig.10 It is a schematic diagram of the three-dimensional structure of the moving contact frame.

[0049] Fig.11 It is a schematic diagram of the three-dimensional structure of the static contact group.

[0050] Fig.12 It is a three-dimensional structural schematic diagram of the internal contact structure of the electromagnetic switch.

[0051] Fig.13 for Fig.12 Schematic diagram of the three-dimensional structure after the first spring button is pressed.

[0052] Fig.14 This is a three-dimensional structural explosion diagram of part of the electromagnetic switch.

[0053] Description of reference numerals:

[0054] 1. Shell; 2. First spring button; 3. Second spring button; 4. Electromagnetic assembly; 5. Coil; 6. Iron core; 7. Armature; 8. Moving contact frame; 9. First elastic member; 10. First moving contact group; 11. First static contact group; 12. Second moving contact group; 13. Second static contact group; 14. Brake static contact group; 15. Steel ball; 16. Boss; 17. Push rod; 18. Panel; 19. Second elastic member; 20. Third elastic member; 21. Fixed seat; 22. Base. DETAILED DESCRIPTION

[0055] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0056] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0059] like Figure 1 As shown, a specific implementation of the electromagnetic switch provided in this embodiment includes: a housing 1, a first spring button 2 disposed on the housing 1, and a second spring button 3 disposed on the housing 1. It should be noted that, as Fig.14As shown, the housing 1 described in this embodiment is composed of three parts: a panel 18, a fixing seat 21 and a base 22, wherein the fixing seat 21 can be used to fix the connection of the static contact group and then fixed in the base 22 by plugging, and the panel 18 is also fixedly connected to the top of the base 22 by plugging.

[0060] The housing 1 includes an electromagnetic assembly 4, which is disposed below the first spring button 2 and opposite to the first spring button 2. The electromagnetic assembly 4 includes a coil 5 and an iron core 6 disposed in the coil 5. When the coil 5 is energized, the iron core 6 can generate magnetic force, thereby adsorbing the armature 7.

[0061] The housing 1 has a contact mechanism, which is arranged below the second spring button 3 and opposite to the second spring button 3. The contact mechanism includes a moving contact frame 8 and a static contact group. The moving contact frame 8 can be relatively slidably arranged in the housing 1 up and down. The static contact group is fixedly connected in the housing 1. The upper end of the moving contact frame 8 is connected to the housing 1 through a first elastic member 9. The first elastic member 9 can be a spring. The moving contact frame 8 can be moved to the bottom position through the first elastic member 9, so that the moving contact group in the moving contact frame 8 is separated from or connected to part of the static contact group. The top end of the moving contact frame 8 can also contact the second spring button 3. When the second spring button 3 is pressed downward, the moving contact frame 8 can be moved downward. One end of the armature 7 can be in contact with the moving contact frame 8. When the iron core 6 of the electromagnetic assembly 4 generates magnetic force and adsorbs the armature 7, one end of the armature 7 can lift the moving contact frame 8 toward the direction close to the second spring button 3, thereby changing the separation or connection state of the moving contact group and the static contact group in the moving contact frame 8.

[0062] The moving contact frame 8 comprises: a first moving contact group 10 and a second moving contact group 12, wherein the first moving contact group 10 and the second moving contact group 12 are electrically connected; the first moving contact group 10 is elastically connected to the moving contact frame 8 through a second elastic member 19 below the first moving contact group 10, and the first moving contact group 10 has a biasing force to move upward through the second elastic member 19, so that when the moving contact frame 8 slides upward, the first moving contact group 10 can contact the first static contact group 11 at the upper end, thereby maintaining electrical connection; when the moving contact frame 8 slides downward, the first moving contact group 10 can contact the brake static contact group 14 at the lower end, thereby maintaining electrical connection; the second moving contact group 12 is elastically connected to the moving contact frame 8 through a third elastic member 20 below the second moving contact group 12, and the second moving contact group 12 has a biasing force to move upward through the third elastic member 20, so that when the moving contact frame 8 slides upward, the second moving contact group 12 can contact the second static contact group 13 at the upper end, thereby maintaining electrical connection.

[0063] like Fig.11 As shown, the static contact group is fixed in the shell, and a plurality of static contact groups constitute a cavity that can accommodate the moving contact, including: a first static contact group 11, a second static contact group 13 and a brake static contact group 14, wherein the first static contact 11 and the second static contact 13 are arranged at the upper end of the cavity, and after the moving contact frame 8 is inserted between the static contact groups, the first static contact group 11 and the second static contact group 13 are located on the side of the moving contact group close to the second spring button 3; and the brake static contact group 14 is arranged at the lower end of the cavity, that is, on the side of the moving contact group away from the second spring button 3.

[0064] The brake static contact group 14 and the first static contact group 11 share a moving contact group. When the moving contact frame 8 is elastically pressed in the lower position by the first elastic member 9, the first moving contact group 10 and the second moving contact group 12 are both moved to the lower end position. At this time, there is a gap between the first moving contact group 10 and the first static contact group 11, and electrical contact is made between the first moving contact group 10 and the brake static contact group 14; the second moving contact group 12 and the second static contact group 13 also maintain a gap, that is, they are disconnected.

[0065] The first moving contact group 10, the second moving contact group 12, the first static contact group 11, the second static contact group 13 and the brake static contact group 14 all have two symmetrical electrical contacts, wherein the two electrical contacts of the brake static contact group 14 are respectively used to electrically connect to the two terminals of the drive motor. When the two electrical contacts of the brake static contact group 14 are connected, the two terminals of the drive motor can be short-circuited, thereby offsetting the instantaneous armature current generated by the rotation of the drive motor. The two electrical contacts of the first moving contact group 10, the second moving contact group 12, the first static contact group 11 and the second static contact group 13 can be two electrical contacts that are symmetrical and electrically connected to each other.

[0066] In the housing 1, the middle of the armature 7 is rotatably connected to the housing 1, and one end thereof extends between the first spring button 2 and the electromagnetic assembly 4. When the first spring button 2 is not pressed, one end of the armature 7 tilts toward the first spring button 2. When the first spring button 2 is pressed, the armature 7 is pressed downward, so that the armature 7 moves toward the iron core 6 of the electromagnetic assembly 4 with the middle thereof as a fulcrum. The other end of the armature 7 extends to one side of the second spring button 3 and contacts with the moving contact frame 8 of the contact mechanism. Specifically, one end of the armature 7 is inserted into the upper end of the moving contact frame 8 for contact cooperation. When one end of the armature 7 approaches the iron core 6, the other end of the armature 7 lifts the moving contact frame 8 upward. After the moving contact frame 8 moves upward after overcoming the elastic force of the first elastic member 9, inside the moving contact frame 8, the first moving contact group 10 and the second moving contact group 12 follow and move upward, so that the first moving contact group 10 is separated from the brake static contact group 14. Then, the first moving contact group 10 contacts the first static contact group 11 to form an electrical connection, and the second moving contact group 12 contacts the second static contact group 13 to form an electrical connection. Since the first moving contact group 10 and the second moving contact group 12 are electrically connected, this action can electrically connect the first static contact group 11 and the second static contact group 13.

[0067] like Figure 2 As shown, a jump structure is provided in the first spring button 2, and the jump structure includes: a steel ball 15 as a blocking member, a spring for pushing the steel ball 15 toward the outside of the push rod 17, and a boss 16 arranged on the sliding path of the push rod 17. The push rod 17 is a part of the first spring button 2, connected below the pressing end of the first spring button 2, and a spring is sleeved on the outside of the push rod 17, one end of the spring is pressed below the pressing end of the first spring button 2, and the other end of the spring is pressed on the housing 1, and the spring is used to enable the first spring button 2 to maintain a pop-up state in a free state.

[0068] The steel balls of this embodiment are symmetrically provided with two springs which are inserted into the push rod 17 and arranged transversely. The two ends of the springs push against a steel ball respectively, so that both steel balls can be kept partially pushed out. As an alternative embodiment, the steel balls can be provided with more than two. The steel balls can be replaced with other parts with arc-shaped structures on the outer surface, such as conical parts.

[0069] like Figure 3 , Figure 4As shown, the lower end of the first moving contact group 10 is connected to the moving contact frame 8 through the second elastic member 19. When the electromagnetic assembly 4 is in a free state without power, the moving contact frame 8 is pushed to move to the lowermost position under the action of the first elastic member 9, and the first moving contact group 10 also moves downward. At this time, the first moving contact group 10 maintains a gap with the first static contact group 11 and maintains contact with the brake static contact group 14.

[0070] like Figure 3 , Figure 5 As shown, the lower end of the second moving contact group 12 is connected to the moving contact frame 8 through the third elastic member 20. When the electromagnetic assembly 4 is in a free state without power, the moving contact frame 8 is pushed to move to the lowermost position under the action of the first elastic member 9, and the second moving contact group 12 also moves downward. At this time, the second moving contact group 12 and the second static contact group 13 are spaced apart.

[0071] like Figure 6 , Fig.13 As shown, after pressing the first spring button 2 downward, the bottom end of the push rod 17 contacts the armature 7 and pushes the armature 7 downward, so that the armature 7 rotates counterclockwise with the middle position as the fulcrum. Thus, the left end of the armature 7 close to the electromagnetic mechanism 4 contacts the iron core 6, and the right end of the armature 7 close to the moving contact frame 8 pries the moving contact frame 8 upward, so that the moving contact frame 8 overcomes the elastic force of the first elastic member 9 and moves upward. When the moving contact frame 8 moves upward, the first moving contact group 10 and the second moving contact group 12 follow and move upward, so that the first moving contact group 10 is separated from the brake static contact group 14 and contacts with the first static contact group 11; the second moving contact group 12 is contacted with the second static contact group 13, so that the motor can be operated, the coil 5 of the electromagnetic assembly 4 is energized, and the iron core 6 keeps adsorbing the armature 7.

[0072] like Figure 7 As shown, after the first spring button 2 is pressed downward, the steel ball 15 has moved downward to the lowest end driven by the push rod 17. In the process of the steel ball 15 moving from the highest end to the lowest end, since a part of the steel ball 15 is pushed out of the push rod 17 by the spring, the steel ball 15 first contacts the boss 16 on the moving path of the push rod 17 in the process of moving downward with the push rod 17. Under the obstruction of the boss 16, a certain resistance is generated when pressing the first spring button 2. When the force of pressing the first spring button 2 downward overcomes the resistance brought by the boss 16, the steel ball 15 turns over the boss 16, so that the push rod 17 can move downward at a relatively high speed, and then the first spring button 2 can be pressed into place at one time.

[0073] like Figure 8As shown, after the armature 7 is pressed, the first spring button 2 is automatically reset under the action of the spring. At this time, since the coil 5 of the electromagnetic assembly 4 is already energized, the iron core 6 can absorb one end of the armature 7 so that the other end of the armature 7 keeps the moving contact frame 8 tilted.

[0074] like Fig. 9 , Fig.12 As shown, after pressing the second spring button 3 downward, the second spring button 3 can push the moving contact frame 8 to move downward, so that the moving contact frame 8 drives the armature 7 to rotate downward, and the armature 7 rotates in the clockwise direction with the middle as the fulcrum. The end of the armature 7 close to the electromagnetic mechanism 4 tilts upward, so that the armature 7 is separated from the iron core 6. After releasing the second spring button 3, the second spring button 3 can be reset and bounced upward under the action of the spring, and the moving contact frame 8 is maintained at the lowest position under the action of the first elastic member 9. The armature 7 is also maintained in a state of tilting toward the direction of the first spring button 2 at one end close to the electromagnetic mechanism 4 because it loses the adsorption of the iron core 6. At this time, the second moving contact group 12 in the moving contact frame 8 is separated from the second static contact group 13, the first moving contact group 10 is separated from the first static contact group 11, and the first moving contact group 10 is in contact with the brake static contact group 14, so that the coil 5 of the electromagnetic assembly 4 is de-energized, the motor is de-energized, and the two terminals of the motor are immediately short-circuited.

[0075] like Fig.10 As shown, two symmetrical first elastic members 9 are provided on both sides of the upper side of the moving contact frame 8, and the first elastic members 9 abut against the panel 18, so that the moving contact frame 8 is kept abutted against the lowermost position on its moving path. The moving contact group is connected in the moving contact frame 8 by a spring, such as the lower end of the second moving contact group 12 is connected to the moving contact frame 8 by the third elastic member 20, so that the second moving contact group 12 can be elastically slidably contacted in the moving contact frame 8.

[0076] like Fig.14 As shown, the first spring button 2 and the second spring button 3 are arranged above the panel 18 through springs. The first spring button 2 can pass through the panel 18 through the push rod 17 to contact the electromagnetic mechanism below; the second spring button 3 also has a corresponding push rod below, which can pass through the panel 18 to contact and cooperate with the moving contact frame 8 below. The first elastic member 9 connected above the moving contact frame 8 contacts the bottom of the panel 18, so that the first elastic member 9 can always provide a downward push force for the moving contact frame 8. The bottom of the panel 18 can be fixed by connecting with the base.

[0077] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. An electromagnetic switch, characterized in that: include: The housing (1) has two spring buttons connected in parallel; An electromagnetic assembly (4) is arranged in the housing (1) and is opposite to the first spring button (2); A contact mechanism, arranged in the housing (1) and opposite to the second spring button (3); An armature (7) is rotatably connected inside the housing (1), one end of which extends to one side of the first spring button (2) and the other end of which extends to one side of the second spring button (3); A kick structure is provided inside the first spring button (2) for providing resistance at the beginning of pressing the first spring button (2); The contact mechanism comprises: a stationary contact group, a moving contact frame (8) and a first elastic member (9); the stationary contact group is fixedly arranged in the housing (1); the moving contact frame (8) is connected to the housing in a manner that it can slide up and down relative to the stationary contact group; the moving contact frame (8) is elastically connected to the moving contact group; the first elastic member (9) is connected between the moving contact frame (8) and the housing (1) and has a biasing force that causes the moving contact frame (8) to move in a direction away from the second spring button (3); The moving contact group comprises: a first moving contact group (10) and a second moving contact group (12); the first moving contact group (10) and the moving contact frame (8) are elastically connected via a second elastic member (19); the second moving contact group (12) and the moving contact frame (8) are elastically connected via a third elastic member (20); the first moving contact group (10) and the second moving contact group (12) are electrically connected; The stationary contact group comprises: a first stationary contact group (11), a second stationary contact group (13) and a brake stationary contact group (14); the first stationary contact group (11) is opposite to the first moving contact group (10) of the moving contact group; the second stationary contact group (13) is opposite to the second moving contact group (12) of the moving contact group; the brake stationary contact group (14) is arranged on the other side of the first moving contact group (10) away from the first stationary contact group (11), and shares the same first moving contact group (10) with the first stationary contact group (11); When one end of the armature (7) approaches the iron core (6) of the electromagnetic assembly (4), the other end of the armature (7) tilts the moving contact frame (8) upward, and the first moving contact group (10) and the second moving contact group (12) move upward accordingly, so that the first moving contact group (10) is separated from the brake static contact group (14) and contacts with the first static contact group (11), and the second moving contact group (12) contacts with the second static contact group (13).

2. The electromagnetic switch according to claim 1, characterized in that: The sudden jump structure comprises: A blocking member, which is laterally connected to the inside of the push rod (17) of the first spring button (2) through a spring, and has an arc-shaped structure protruding from the push rod (17); The boss (16) is arranged on the sliding path of the push rod (17) and is suitable for contacting the arc-shaped structure of the blocking member.

3. The electromagnetic switch according to claim 2, characterized in that: The blocking member is spherical or conical.

4. The electromagnetic switch according to claim 2 or 3, characterized in that: There are a plurality of blocking members on the push rod (17).

5. The electromagnetic switch according to claim 4, characterized in that: A plurality of blocking members are evenly arranged on the push rod (17) along the circumferential direction.

6. The electromagnetic switch according to any one of claims 1 to 5, characterized in that: The first moving contact group (10), the first stationary contact group (11) and the brake stationary contact group (14) all have two symmetrical electrical contacts.

7. The electromagnetic switch according to claim 6, characterized in that: The two electrical contacts of the brake static contact group (14) are used to be electrically connected to the two wiring terminals of the drive motor respectively.

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