A repetitive start-up system for a motor, its preparation method and control method

Abstract

This invention discloses a repetitive starting system, its preparation method, and its control method for starting a motor. The system includes a dual-winding coil assembly, a capacitor, a contact assembly, and an insulating plate. The dual-winding coil assembly and the capacitor are mounted on the insulating plate. The contact assembly includes a stationary contact unit and a moving contact unit. The stationary contact unit includes a stationary contact support and a stationary contact. The moving contact unit includes a moving contact support, a spring plate, an armature, and a moving contact. The bottom end of the moving contact support is fixed to the insulating plate. One end of the spring plate is connected to the top end of the moving contact support, and the other end of the spring plate is connected to the armature. The moving contact is located on the armature, and one end of the armature is located above the top end of the dual-winding coil assembly. One end of the forward winding is connected to one end of the capacitor, and one end of the reverse winding is connected to the other end of the capacitor. The other ends of both the forward and reverse windings are connected to the stationary contact unit. This invention has a simple overall structure, small size, light weight, stable performance, and high reliability.

Description

Technical Field

[0001] This invention relates to the field of diesel engine starting technology, specifically to a repetitive starting system for a motor, its preparation method, and its control method. Background Technology

[0002] Repeatable starters are widely used in the starting of marine diesel engine motors. When the motor starts, the repeatable starter provides a large starting current; if the motor fails to start, it provides an intermittent starting current to prevent damage from continuous high current. A repeatable starter mainly consists of a repeatable start system and a starting relay. Currently used repeatable start systems primarily consist of a clock chip and its associated circuitry. While they can provide intermittent starting signals, their complex structure and low stability make them unsuitable for the marine operating environment. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: in view of the problems existing in the prior art, the present invention provides a repetitive starting system for starting a motor that can provide intermittent signals, a preparation method and a control method.

[0004] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0005] A repetitive starting system for a motor includes a dual-winding coil assembly, a capacitor, a contact assembly, and an insulating plate. The bottom end of the dual-winding coil assembly is mounted on the insulating plate, and the dual-winding coil assembly includes a forward winding and a reverse winding. The contact assembly includes a stationary contact unit and a moving contact unit. The stationary contact unit includes a stationary contact bracket and a stationary contact; the bottom end of the stationary contact bracket is mounted on the insulating plate, and the stationary contact is mounted on the top of the stationary contact bracket. The moving contact unit includes a moving contact bracket, a spring plate, an armature, and... The moving contact has its bottom end fixed to the insulating plate. One end of the spring sheet is connected to the top end of the moving contact bracket, and the other end of the spring sheet is connected to the armature. The moving contact is located on the armature, and one end of the armature is located above the top end of the double-winding coil assembly. The capacitor is located on the insulating plate. One end of the forward winding is connected to one end of the capacitor, and one end of the reverse winding is connected to the other end of the capacitor. The other ends of both the forward and reverse windings are connected to the stationary contact unit.

[0006] As a further improvement to the above technical solution:

[0007] The dual-winding coil assembly also includes an iron core, an upper baffle, a lower baffle, and pole shoes. The upper baffle is located on the upper part of the iron core, and the lower baffle is located on the lower part of the iron core. An iron core insulation layer is wound on the iron core. The forward winding and the reverse winding are alternately wound on the iron core insulation layer, and the outermost winding is wound with a winding insulation layer.

[0008] One end of the forward winding is connected to a forward winding electrode, and one end of the reverse winding is connected to a reverse winding electrode. The other ends of both the forward and reverse windings are connected to a common winding electrode. A stationary contact electrode is connected to the bottom of the stationary contact unit, and a moving contact electrode is connected to the bottom of the moving contact unit. The capacitor has a positive terminal and a negative terminal at its two ends. The forward winding electrode, reverse winding electrode, common winding electrode, stationary contact electrode, moving contact electrode, positive terminal, and negative terminal are all mounted through the insulating plate. The reverse winding electrode and forward winding electrode are connected to the positive and negative terminals of the capacitor via wires, and the common winding electrode is connected to either the moving contact electrode or the stationary contact electrode via a wire.

[0009] The capacitor is an adjustable capacitor.

[0010] It also includes a housing, which is covered by the insulating plate, and the dual-winding coil assembly, capacitor, and contact assembly are all located within the space formed by the housing and the insulating plate.

[0011] The spring sheet is made of steel, and the stationary contact unit, moving contact bracket, armature, and moving contact are all made of copper, steel, or stainless steel.

[0012] The insulating board is an epoxy resin board.

[0013] The present invention also discloses a method for preparing a repetitive start system for a motor as described above, comprising the steps of:

[0014] Step 1: Set the forward winding electrode, reverse winding electrode, winding common electrode, moving contact electrode, stationary contact electrode, capacitor positive electrode and capacitor negative electrode on the insulating board, with each electrode penetrating the insulating board;

[0015] Step 2: Prepare a double-winding coil assembly. Set an upper baffle and a lower baffle on the upper and lower parts of the iron core respectively. Use polyimide tape to wrap around the iron core to form an iron core insulation layer. Alternately wrap the forward winding and the reverse winding outside the insulation layer. Use polyimide tape to wrap around the winding to form a winding insulation layer. Set a pole shoe on the top of the upper baffle.

[0016] Step 3: Fix the dual-winding coil assembly on the insulating board, install the moving contact on the moving contact bracket, install the stationary contact on the stationary contact bracket, and install the moving contact bracket and the stationary contact bracket on the insulating board to keep the moving contact and the stationary contact closed; one end of the spring sheet is installed on the moving contact bracket, and the other end is connected to the armature; the armature is located directly above the pole shoe and maintains an appropriate distance from the pole shoe;

[0017] Step 4: Connect the other ends of the forward winding and the reverse winding to the common electrode of the winding by welding. Connect the common electrode of the winding to the stationary contact electrode by a wire. Connect the other end of the forward winding to the forward winding electrode by welding, and connect the other end of the reverse winding to the reverse winding electrode by welding. Connect the positive terminal of the capacitor to the reverse winding electrode by a wire, and connect the negative terminal of the capacitor to the forward winding electrode by a wire.

[0018] Step 5: Install the housing on the insulating board, and enclose the dual-winding coil assembly, contact assembly and capacitor between the insulating board and the housing.

[0019] As a further improvement to the above technical solution:

[0020] In step three, the moving contact bracket and the stationary contact bracket are connected to the moving contact electrode and the stationary contact electrode respectively by welding; the other end of the spring sheet is connected to the armature by bolts.

[0021] This invention also discloses a control method for a repetitive starting system of a motor as described above, wherein the moving contact unit is connected to the positive terminal of a DC power supply, and its voltage is U; the positive winding electrode is connected to the negative terminal of a DC power supply, and its voltage is 0; the stationary contact unit forms the output terminal, and the specific steps are as follows:

[0022] S1. The moving contact unit and the stationary contact unit of the contact assembly are in a closed state, and the voltage at the output terminal is U.

[0023] S2. The capacitor begins to charge, and current flows through both its forward and reverse windings. The magnetic fields generated cancel each other out, and the moving contact unit and the stationary contact unit remain closed. The voltage at the output terminal is U.

[0024] S3. When the capacitor is fully charged, current flows through the forward winding and no current flows through the reverse winding. The moving contact unit and the stationary contact unit are disconnected, and the voltage at the output terminal is 0.

[0025] S4. The capacitor begins to discharge, current flows through the forward winding, and reverse current also flows through the reverse winding, maintaining the disconnected state between the moving contact unit and the stationary contact unit, and the voltage at the output terminal is 0.

[0026] S5. After the capacitor discharges, no current flows through either the forward or reverse winding. The moving contact unit and the stationary contact unit return to their normally closed state, and the voltage at the output terminal is U.

[0027] Compared with the prior art, the advantages of the present invention are as follows:

[0028] The repetitive starting system for motors of the present invention uses the charging and discharging of a capacitor to allow current to flow in the forward and reverse windings, thereby enabling the dual-winding coil assembly to attract and release the armature under different charging and discharging conditions of the capacitor, and thus enabling the closing and opening of the contact assembly, ultimately providing an intermittent signal voltage; the overall structure is simple, uses few components, is small in size, light in weight, and consumes little power; it is unaffected by external interference, has good environmental adaptability, stable performance, and high reliability. Attached Figure Description

[0029] Figure 1 This is a front view structural diagram of the repeatable restart system of the present invention in an embodiment.

[0030] Figure 2 This is a cross-sectional view of the dual-winding coil assembly of the present invention in an embodiment.

[0031] Figure 3 This is a circuit schematic diagram of the repeatable restart system of the present invention in an embodiment.

[0032] Figure 4 This is a diagram of the output signals of the repeatable restart system of the present invention in an embodiment.

[0033] Legend: 1. Insulating plate; 2. Double-winding coil assembly; 21. Lower baffle; 22. Iron core; 23. Iron core insulation layer; 24. Forward winding; 25. Reverse winding; 26. Winding insulation layer; 27. Upper baffle; 28. Pole shoe; 31. Forward winding electrode; 32. Winding common electrode; 33. Reverse winding electrode; 41. Armature; 42. Spring plate; 43. Moving contact; 44. Moving contact bracket; 45. Moving contact electrode; 46. Stationary contact; 47. Stationary contact bracket; 48. Stationary contact electrode; 49. Bolt; 5. Capacitor; 51. Capacitor positive terminal; 52. Capacitor negative terminal; 6. Housing. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0035] like Figures 1-3As shown, the repetitive starting system for a motor according to an embodiment of the present invention includes a dual-winding coil assembly 2, a capacitor 5, a contact assembly, and an insulating plate 1. The bottom end of the dual-winding coil assembly 2 is mounted on the insulating plate 1. The dual-winding coil assembly 2 includes a forward winding 24 and a reverse winding 25. The contact assembly includes a stationary contact unit and a moving contact unit. The stationary contact unit is mounted on the insulating plate 1 and specifically includes a stationary contact 46 and a stationary contact bracket 47. The bottom end of the stationary contact bracket 47 is mounted on the insulating plate 1, and the stationary contact 46 is mounted on the top of the stationary contact bracket 47. The moving contact unit includes a moving contact bracket 44 and a spring. The spring 42, armature 41, and moving contact 43 are fixed at the bottom of the moving contact bracket 44. One end of the spring 42 is connected to the top of the moving contact bracket 44, and the other end of the spring 42 is connected to the armature 41. The moving contact 43 is located on the armature 41. One end of the armature 41 is located above the top of the double-winding coil assembly 2. The capacitor 5 is located on the insulating plate 1. One end of the forward winding 24 is connected to one end of the capacitor 5, and one end of the reverse winding 25 is connected to the other end of the capacitor 5. The other ends of the forward winding 24 and the reverse winding 25 are both connected to the stationary contact unit or the moving contact unit.

[0036] The repetitive starting system for a motor of the present invention uses the charging and discharging of capacitor 5 to allow current to flow in the forward winding 24 and the reverse winding 25, thereby enabling the dual-winding coil assembly 2 to attract and release the armature 41 under different charging and discharging conditions of capacitor 5, and thus realizing the closing and opening of the contact assembly, ultimately providing an intermittent signal voltage; the overall structure is simple, uses few components, and is small in size, light in weight, and consumes little power; it is not affected by external interference, has good environmental adaptability, stable performance, and high reliability.

[0037] In one specific embodiment, the dual-winding coil assembly 2 further includes an iron core 22, an upper baffle 27, a lower baffle 21, and pole shoes 28. The upper baffle 27 is located above the iron core 22, and the lower baffle 21 is located below the iron core 22. An iron core insulation layer 23 is wound on the iron core 22. The forward winding 24 and the reverse winding 25 are alternately wound on the iron core insulation layer 23, and the outermost winding is wound with a winding insulation layer 26. The material of the forward winding 24 and the reverse winding 25 is fine copper wire with an insulating surface.

[0038] In one specific embodiment, one end of the forward winding 24 is connected to the forward winding electrode 31, one end of the reverse winding 25 is connected to the reverse winding electrode 33, and the other ends of both the forward winding 24 and the reverse winding 25 are connected to the winding common electrode 32. The bottom end of the stationary contact unit is connected to the stationary contact electrode 48, and the bottom end of the moving contact unit is connected to the moving contact electrode 45. The two ends of the capacitor 5 are respectively provided with a capacitor positive electrode 51 and a capacitor negative electrode 52. The forward winding electrode 31, the reverse winding electrode 33, the winding common electrode 32, the stationary contact electrode 48, the moving contact electrode 45, the capacitor positive electrode 51, and the capacitor negative electrode 52 are all installed through the insulating plate 1. The reverse winding electrode 33 and the forward winding electrode 31 are respectively connected to the capacitor positive electrode 51 and the capacitor negative electrode 52 through wires. The winding common electrode 32 is connected to the moving contact electrode 45 or the stationary contact electrode 48 through wires.

[0039] In one specific embodiment, the system further includes a housing 6, which covers the insulating plate 1. The dual-winding coil assembly 2, capacitor 5, and contact assembly are all located within the space formed by the housing 6 and the insulating plate 1, thereby protecting each component. The housing 6 is provided with mounting holes for easy installation.

[0040] In one specific embodiment, capacitor 5 is an adjustable capacitor, and the output time and interruption time of the control signal can be adjusted by configuring the size of capacitor 5 and the number of turns of the forward winding 24 and the reverse winding 25, thereby providing an adjustable intermittent control signal.

[0041] like Figure 1 and Figure 2 As shown in the figure, this invention also discloses a method for preparing a repetitive start system for a motor as described above, comprising the following steps:

[0042] Step 1: Set the forward winding electrode 31, reverse winding electrode 33, winding common electrode 32, moving contact electrode 45, stationary contact electrode 48, capacitor positive electrode 51, and capacitor negative electrode 52 on the insulating plate 1. Each electrode passes through the insulating plate 1, which can realize the function of internal connection and external output; wherein the insulating plate 1 is preferably an epoxy resin board.

[0043] Step 2: Prepare the double-winding coil assembly 2. Set an upper baffle 27 and a lower baffle 21 on the upper and lower parts of the iron core 22, respectively. The upper baffle 27 and the lower baffle 21 are made of epoxy resin board. Use polyimide tape to wrap around the iron core 22 to form an iron core insulation layer 23. Alternately wind forward winding 24 and reverse winding 25 outside the insulation layer. Use polyimide tape to wrap around the winding to form a winding insulation layer 26. Set a pole shoe 28 on the top of the upper baffle 27. The pole shoe 28 is made of nickel-plated steel.

[0044] Step 3: Fix the double-winding coil to the insulating plate 1 with insulating silicone. Install the moving contact 43 on the moving contact bracket 44 and the stationary contact 46 on the stationary contact bracket 47. The moving contact bracket 44 and the stationary contact bracket 47 are installed on the insulating plate 1, keeping the moving contact 43 and the stationary contact 46 closed. The moving contact bracket 44 and the stationary contact bracket 47 are connected to the moving contact electrode 45 and the stationary contact electrode 48 respectively by welding. One end of the spring plate 42 is installed on the moving contact bracket 44, and the other end is connected to the armature 41 using bolts 49. The spring plate 42 is made of thin steel sheet. The armature 41 is located directly above the pole shoe 28 and maintains an appropriate distance from the pole shoe 28. The moving contact bracket 44, the stationary contact bracket 47, the moving contact 43, and the stationary contact 46 can be made of materials with good conductivity, such as copper, steel, or stainless steel.

[0045] Step 4: Connect one end of the forward winding 24 and the reverse winding 25 to the common winding electrode 32 by welding. Connect the common winding electrode 32 to the stationary contact electrode 48 by wire. Connect the other end of the forward winding 24 to the forward winding electrode 31 by welding. Connect the other end of the reverse winding 25 to the reverse winding electrode 33 by welding. Connect the positive terminal 51 of the capacitor 5 to the reverse winding electrode 33 by wire. Connect the negative terminal 52 of the capacitor 5 to the forward winding electrode 31 by wire.

[0046] Step 5: Install the housing 6 on the insulating plate 1. The double-winding coil assembly 2, normally closed contact assembly, and capacitor 5 are enclosed between the insulating plate 1 and the housing 6. The housing 6 can be made of insulating material or metal material with surface insulation treatment, preferably aluminum alloy with surface insulation treatment.

[0047] like Figure 3 and Figure 4 As shown, this embodiment of the invention also discloses a control method based on the above-described repetitive start system for a motor, specifically: the moving contact electrode 45 is connected to the positive terminal of a DC power supply, and its voltage is U; the positive winding electrode 31 is connected to the negative terminal of a DC power supply, and its voltage is 0; the stationary contact electrode 48 forms the output terminal; the steps of a single cycle include:

[0048] S1. The moving contact 43 unit and the stationary contact 46 unit of the contact assembly are in a closed state, and the voltage at the output terminal is U.

[0049] S2, capacitor 5 starts charging, and positive current flows through its forward winding 24 and reverse winding 25. The magnetic fields generated cancel each other out, and the moving contact 43 unit and the stationary contact 46 unit remain closed. The voltage at the output terminal is U.

[0050] S3. When capacitor 5 is fully charged, current flows through the forward winding 24, and no current flows through the reverse winding 25. The moving contact 43 unit and the stationary contact 46 unit are disconnected (at this time, pole shoe 28 pulls armature 41 downward, so that the moving contact 43 and the stationary contact 46 below armature 41 are staggered and disconnected), and the voltage at the output terminal is 0.

[0051] S4, capacitor 5 starts to discharge, current flows through the forward winding 24, and reverse current also flows through the reverse winding 25, maintaining the disconnected state between the moving contact 43 unit and the stationary contact 46 unit, and the voltage at the output terminal is 0.

[0052] After S5 and capacitor 5 have finished discharging, no current flows through the forward winding 24 and the reverse winding 25. The moving contact 43 unit and the stationary contact 46 unit return to the normally closed state, and the voltage at the output terminal is U.

[0053] Specifically, in each of the above steps, as long as there is current flowing through the forward winding 24 and no current flowing through the reverse winding 25, or if there is current flowing through the forward winding 24 and a reverse current flowing through the reverse winding 25, the pole shoe 28 will have an attractive force to hold the armature 41, and the moving contact 43 and the stationary contact 46 will be in the open state; while when there is no current flowing through the forward winding 24, or when there is current flowing through the forward winding 24 and a positive current flowing through the reverse winding 25, the pole shoe 28 will have no attractive force, the armature 41 will be in the normal state, and the moving contact 43 and the stationary contact 46 will be in the normally closed state.

[0054] like Figure 4 As shown, there is a signal voltage U at the output terminal in steps S1 and S2, but no signal voltage in steps S3 and S4, thus forming an intermittent signal voltage.

[0055] As shown in this disclosure and the claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. The terms "connected" or "linked" are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect.

[0056] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a repetitive start system for a motor, characterized in that, The repetitive starting system for the motor includes a dual-winding coil assembly (2), a capacitor (5), a contact assembly, and an insulating plate (1). The bottom end of the dual-winding coil assembly (2) is mounted on the insulating plate (1). The dual-winding coil assembly (2) includes a forward winding (24) and a reverse winding (25). The contact assembly includes a stationary contact unit and a moving contact unit. The stationary contact unit includes a stationary contact bracket (47) and a stationary contact (46). The bottom end of the stationary contact bracket (47) is mounted on the insulating plate (1), and the stationary contact (46) is mounted on the top of the stationary contact bracket (47). The moving contact unit includes a moving contact bracket (44), a spring plate (42), an armature (41), and a moving contact (43). The bottom end of the moving contact bracket (44) is fixed on the insulating plate (1), one end of the spring sheet (42) is connected to the top end of the moving contact bracket (44), the other end of the spring sheet (42) is connected to the armature (41), the moving contact (43) is located on the armature (41), one end of the armature (41) is located above the top end of the double winding coil assembly (2), and the capacitor (5) is located on the insulating plate (1); one end of the forward winding (24) is connected to one end of the capacitor (5), one end of the reverse winding (25) is connected to the other end of the capacitor (5), and the other ends of the forward winding (24) and the reverse winding (25) are both connected to the stationary contact unit; The dual-winding coil assembly (2) also includes an iron core (22), an upper baffle (27), a lower baffle (21), and a pole shoe (28). The upper baffle (27) is located on the upper part of the iron core (22), and the lower baffle (21) is located on the lower part of the iron core (22). An iron core insulation layer (23) is wound on the iron core (22). The forward winding (24) and the reverse winding (25) are alternately wound on the iron core insulation layer (23). The outermost winding is wound with a winding insulation layer (26). One end of the forward winding (24) is connected to a forward winding electrode (31), and one end of the reverse winding (25) is connected to a reverse winding electrode (33). The other ends of the forward winding (24) and the other ends of the reverse winding (25) are both connected to a common winding electrode (32). The bottom end of the stationary contact unit is connected to a stationary contact electrode (48), and the bottom of the moving contact unit is connected to a moving contact electrode (45). The capacitor (5) has a positive electrode (51) and a negative electrode (52) at its two ends, respectively. The forward winding electrode (31), reverse winding electrode (33), winding common electrode (32), stationary contact electrode (48), moving contact electrode (45), capacitor positive electrode (51), and capacitor negative electrode (52) are all installed through the insulating plate (1); the forward winding electrode (31) and reverse winding electrode (33) are connected to the capacitor positive electrode (51) and capacitor negative electrode (52) respectively by wires, and the winding common electrode (32) is connected to the stationary contact electrode (48) by wires; The preparation method includes the following steps: Step 1: Set up the forward winding electrode (31), reverse winding electrode (33), winding common electrode (32), moving contact electrode (45), stationary contact electrode (48), capacitor positive electrode (51) and capacitor negative electrode (52) on the insulating plate (1), with each electrode penetrating the insulating plate (1); Step 2: Prepare a double-winding coil assembly (2). Set an upper baffle (27) and a lower baffle (21) on the upper and lower parts of the iron core (22) respectively. Use polyimide tape to wrap the iron core (22) to form an iron core insulation layer (23). Alternately wrap the forward winding (24) and the reverse winding (25) outside the iron core insulation layer (23). Use polyimide tape to wrap the outside of the winding to form a winding insulation layer (26). Set a pole shoe (28) on the top of the upper baffle (27). Step 3: Fix the double-winding coil assembly (2) on the insulating plate (1), install the moving contact (43) on the moving contact bracket (44), install the stationary contact (46) on the stationary contact bracket (47), and install the moving contact bracket (44) and the stationary contact bracket (47) on the insulating plate (1) so that the moving contact (43) and the stationary contact (46) remain closed; one end of the spring sheet (42) is installed on the moving contact bracket (44), and the other end is connected to the armature (41); the armature (41) is located directly above the pole shoe (28) and maintains an appropriate distance from the pole shoe (28); Step 4: Connect the other ends of the forward winding (24) and the reverse winding (25) to the common winding electrode (32) by welding. Connect the common winding electrode (32) to the stationary contact electrode (48) by wire. Connect one end of the forward winding (24) to the forward winding electrode (31) by welding. Connect one end of the reverse winding (25) to the reverse winding electrode (33) by welding. Connect the positive terminal of the capacitor (5) to the reverse winding electrode (33) by wire. Connect the negative terminal of the capacitor (5) to the forward winding electrode (31) by wire. Step 5: Install the housing (6) on the insulating plate (1), and enclose the double winding coil assembly (2), contact assembly and capacitor (5) between the insulating plate (1) and the housing (6).

2. The preparation method according to claim 1, characterized in that, In step three, the moving contact bracket (44) and the stationary contact bracket (47) are connected to the moving contact electrode (45) and the stationary contact electrode (48) respectively by welding; the other end of the spring sheet (42) is connected to the armature (41) by bolt (49).

3. The preparation method according to claim 1 or 2, characterized in that, The capacitor (5) is an adjustable capacitor.

4. The preparation method according to claim 1 or 2, characterized in that, It also includes a housing (6), which covers the insulating plate (1), and the dual-winding coil assembly (2), capacitor (5) and contact assembly are all located in the space formed by the housing (6) and the insulating plate (1).

5. The preparation method according to claim 1 or 2, characterized in that, The spring sheet (42) is made of steel, and the stationary contact unit, the moving contact bracket (44), the armature (41) and the moving contact (43) are all made of copper, steel or stainless steel.

6. The preparation method according to claim 1 or 2, characterized in that, The insulating board (1) is an epoxy resin board.

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