Monostable switch, bistable switch device, bistable pressure automatic switch and control method

Abstract

The present invention provides a monostable switch, a bistable switch device, a bistable pressure automatic switch and a control method, which fundamentally solve the problems that the pressure difference (the difference between the starting value and the stopping value) of various existing pressure switches cannot be adjusted during production and use, and the starting value, the stopping value and the pressure difference are inconsistent. The starting value, the stopping value and the pressure difference can be independently set respectively, and the structure is simpler, more practical and has a higher cost performance than the existing bistable switch; after the switch of the present invention is used, it can greatly reduce product scrapping and avoid major accidents such as burning motors, laying a solid foundation for product upgrading; it greatly enhances the environmental adaptability of existing products, and significantly improves the technical performance, control accuracy, service performance, service life and economic benefits of existing products.

Description

Technical Field

[0001] The present invention relates to the field of automatic control, and particularly to a monostable switch, a bistable switch device, a bistable pressure automatic switch and a control method. Background Art

[0002] All existing types of pressure switches have a common drawback during production and use. That is, when setting the starting value, stopping value and pressure difference (the difference between the starting value and the stopping value), due to the limitations of their structures, the pressure difference is basically a non-adjustable fixed value. Therefore, the starting value, stopping value and pressure difference are inconsistent and cannot be set independently. This will cause a common fatal defect in existing products. When the pressure difference changes during manufacturing and use, it will cause a large number of product scraps and even major accidents such as burning motors. Moreover, all existing types of bistable pressure automatic switches rely too much on materials and processes, resulting in increased manufacturing costs and decreased cost performance of the products. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a simple and practical monostable switch, a bistable switch device, a bistable pressure automatic switch and a control method that can independently adjust the starting value and the stopping value respectively and the pressure difference is adjustable.

[0004] One of the technical solutions adopted by the present invention to solve the above technical problems: a monostable switch includes a switch body and a switch device. The switch device is arranged in the switch body. The switch device includes a fork, a static contact, a moving contact and a lower fulcrum. The static contact is arranged in the upper part of the switch body, and the lower fulcrum is arranged in the lower part of the switch body. A guiding structure is arranged on the switch body to enable the fork to move linearly up and down in the switch body. The fork is provided with a moving contact for closing and opening the switch device.

[0005] The second technical solution adopted by the present invention to solve the above technical problems: A dual-tuning switch device, comprising a dual-tuning device, a bracket, a support spring, and a monostable switch. The dual-tuning device includes a starting bolt, a return spring, a stopping bolt, and a stopping nut seat. The stopping bolt is screwed into the stopping nut seat. The stopping bolt is a hollow bolt. The starting bolt is screwed to the stopping bolt and can be rotated up and down in the hollow of the stopping bolt for adjustment. The return spring is arranged between the starting bolt and the fork. Its upper part abuts against the starting bolt, and its lower part abuts against the fork. The stopping nut seat is rigidly connected to the bracket. A guide rail structure is provided on the bracket. The switch body is arranged in the middle of the bracket. Its lower part abuts against the support spring and can freely move up and down along the bracket between the stopping nut seat and the support spring. The two ends of the support spring are respectively supported between the switch body and the bracket. A control method for the dual-tuning switch device: Set the elastic force of the return spring to be greater than the flipping force of the moving contact. When the fork is not subjected to an external P-directional thrust, due to the elastic force of the return spring, the moving contact and the static contact in the monostable switch are in a contact state. When the fork moves upward under the action of an external P-directional thrust, it simultaneously pushes the monostable switch to compress the return spring and move upward, driving the static contact to move upward. After the switch body abuts against the bottom of the stopping bolt, the monostable switch stops moving. At this time, the static contact acts as a fulcrum. The fork continues to move upward. After the moving contact crosses the balance point of the static contact, it flips, and the moving contact and the static contact are in a separated state. At this time, adjust the stopping bolt to a suitable stopping position. When the thrust received by the fork weakens, under the action of the return spring, the monostable switch moves downward. When the return spring and the support spring reach the elastic force balance point, the monostable switch stops moving. At this time, due to the support of the lower fulcrum, as long as the external P-directional thrust continues to weaken, under the elastic force of the return spring and the support of the lower fulcrum, the fork will continue to push the center of the moving contact downward. When crossing the balance point of the lower fulcrum, the moving contact flips, and the moving contact and the static contact in the monostable switch resume the contact state. At this time, adjust the starting bolt to a suitable starting position.

[0006] The third technical solution adopted by the present invention to solve the above technical problems: A dual-adjustment type pressure automatic switch, comprising a dual-adjustment switch device, a base, a pressure ring, a test spring, a thrust rod and an elastic sealing gasket. The base is hermetically connected to the bracket. Inside the base, there are arranged a pressure ring, an elastic sealing gasket, a test spring and a thrust rod. The test spring is sleeved on the thrust rod. The thrust rod is T-shaped, with its upper part being a rod portion and a protrusion being arranged at the bottom. The test spring is supported between the bottom protrusion of the thrust rod and the bracket. A pressure ring is arranged between the bracket and the base. The pressure ring is fixed between the bracket and the base. The lower end face of the pressure ring abuts against the elastic sealing gasket, fixing the elastic sealing gasket on the base. There is a protrusion arranged on the inner periphery of the bottom of the pressure ring. The elastic sealing gasket is seated on the base and supported between the base and the pressure ring, with one side abutting against the base and the other side abutting against the pressure ring. The upper end of the thrust rod passes through the bracket and faces the lower end face of the fork, and the lower end abuts against the upper end face of the elastic sealing gasket. There is an adjustment gap between the lower end face of the fork and the upper end face of the thrust rod. The control method of the dual-adjustment type pressure automatic switch: Set the elastic force of the return spring to be greater than the flipping force of the moving contact. When liquid or gas enters the inlet of the base along the P direction, in the case of zero or very weak pressure, the moving contact and the static contact in the monostable switch are in a contact state, and the dual-adjustment type pressure automatic switch is in a closed state. When the pressure gradually increases, it pushes the thrust rod to move upward and compress the test spring, and at the same time pushes the fork to move upward, thereby pushing the monostable switch to compress the return spring and move upward, and driving the static contact to move upward. When the switch body abuts against the bottom of the stop bolt, the monostable switch and the return spring stop moving. At this time, the static contact plays a fulcrum role, and the fork continues to move upward. After the moving contact exceeds the fulcrum balance point, it flips. The moving contact and the static contact in the monostable switch are in a separated state, and the dual-adjustment type pressure automatic switch is in an open state. Adjust the stop bolt to an appropriate stop position. When the liquid or gas pressure weakens, the thrust received by the fork weakens. Under the action of the return spring, it pushes the monostable switch to move downward. After reaching the elastic force balance point of the return spring and the support spring, the monostable switch stops moving. At this time, the lower fulcrum plays a supporting role. The fork continues to move downward under the elastic force push of the return spring, and the thrust rod also moves downward correspondingly under the elastic force of the test spring. After the moving contact crosses the lower fulcrum balance point, it flips, and the moving contact and the static contact resume the contact state, and the dual-adjustment type pressure automatic switch immediately enters the closed state;At this time, just adjust the starting bolt to the appropriate starting position.

[0007] Compared with the prior art, the advantages of the present invention are as follows: fundamentally solving the problems that the pressure difference (the difference between the starting value and the stopping value) of various existing pressure switches cannot be adjusted during production and use, and the starting value, stopping value and pressure difference are inconsistent; the starting value, stopping value and pressure difference can be independently set respectively, and the structure is simpler and more practical than the existing double-adjustment switch, with higher cost performance; after the switch of the present invention is used, it can greatly reduce product scrapping and avoid major accidents such as burning motors, laying a solid foundation for product upgrading; greatly enhancing the environmental adaptability of existing products, and significantly improving the technical performance, control accuracy, service performance, service life and economic benefits of existing products. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 FIG. is a schematic structural diagram of the monostable switch in Embodiment 1 of the present invention;

[0009] Figure 2 FIG. is a schematic structural diagram of the monostable switch in Embodiment 2 of the present invention;

[0010] Figure 3 FIG. is a front view structural diagram of the moving contact in Embodiment 1 of the present invention;

[0011] Figure 4 FIG. is a top view structural diagram of the moving contact in Embodiment 1 of the present invention;

[0012] Figure 5 FIG. is a front view structural diagram of the moving contact in Embodiment 2 of the present invention;

[0013] Figure 6 FIG. is a top view structural diagram of the moving contact in Embodiment 2 of the present invention;

[0014] Figure 7 FIG. is a top view structural diagram of the fork of the present invention;

[0015] Figure 8 FIG. is a front view structural diagram of the fork of the present invention;

[0016] Figure 9 FIG. is a bottom view structural diagram of the fork of the present invention;

[0017] Figure 10 FIG. is a structural diagram of the moving contact and the static contact of the double-adjustment switch device of the present invention when they are in contact;

[0018] Figure 11 FIG. is a structural diagram of the moving contact and the static contact of the double-adjustment switch device of the present invention when they are separated;

[0019] Figure 12 FIG. is a schematic diagram of the adjustment structure of the double-adjustment device of the present invention;

[0020] Figure 13 This is a top view structural schematic diagram of the stop bolt of the present invention;

[0021] Figure 14 This is a front view structural schematic diagram of the stop bolt of the present invention;

[0022] Figure 15 This is a top view structural schematic diagram of the start bolt of the present invention;

[0023] Figure 16 This is a front view structural schematic diagram of the start bolt of the present invention;

[0024] Figure 17 This is a bottom view structural schematic diagram of the start bolt of the present invention;

[0025] Figure 18 This is a structural schematic diagram of the present invention when the moving contact and the static contact of the dual-adjustment type pressure automatic switch are in a contact state;

[0026] Figure 19 This is a structural schematic diagram of the present invention when the moving contact and the static contact of the dual-adjustment type pressure automatic switch are in a separated state;

[0027] Figure 20 This is a structural schematic diagram of the present invention when the moving contact and the static contact of the dual-adjustment type pressure automatic switch are in a contact state;

[0028] Figure 21 This is a structural schematic diagram of the present invention when the moving contact and the static contact of the dual-adjustment type pressure automatic switch are in a separated state.

[0029] In the above figures:

[0030] 1. Switch body, 2. Static contact, 3. Lower fulcrum, 4. Elastic sheet moving contact, 5. Moving contact, 6. Moving contact piece, 7. Fork, 8. Start bolt, 9. Stop bolt, 10. Stop nut seat, 11. Return spring, 12. Support spring, 13. Test spring, 14. Bracket, 15. Pressure ring, 16. Base, 17. Thrust rod, 18. Elastic gasket, 19. Contact spring. Specific embodiments

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

[0032] Embodiment 1: As shown in Figures 1 - 9As shown in the figure, a monostable switch includes a switch body 1. There are upper through holes and lower through holes provided on the switch body. A switch device is arranged in the switch body 1. The switch device includes a fork 7, a static contact 2, a moving contact 5 and a lower fulcrum 3. The static contact 2 is arranged at the upper part inside the switch body 1, and the lower fulcrum 3 is arranged at the corresponding lower part inside the switch body 1. The upper end of the fork passes through the upper through hole, and the lower end passes through the lower through hole. Both the upper through hole and the lower through hole are polygonal inner through holes. Both the upper and lower ends of the fork 7 are arranged as polygonal cylinders adapted to the polygonal inner through holes to ensure that the upper and lower ends of the fork do not undergo overall deflection when passing through the polygonal inner through holes on the switch body 1. The fork 7 can move linearly up and down in the switch body 1. Upper and lower limit protrusions are provided on the fork 7 to limit the movement stroke of the moving contact 5. The lower limit protrusion is supported on the switch body 1. A moving contact 5 is arranged on the fork 7. Here, the moving contact 5 is an example of a spring-type moving contact 5 (as shown in Figure 1 ), and is used for the closing and opening of the switch device. Without any external force pushing the fork 7, the monostable switch always remains in the closed state.

[0033] Embodiment 2: As shown in Figures 1 - 9 , a monostable switch includes a switch body 1. There are upper through holes and lower through holes provided on the switch body. A switch device is arranged in the switch body 1. The switch device includes a fork 7, a static contact 2, a moving contact 5 and a lower fulcrum 3. The static contact 2 is arranged at the upper part inside the switch body 1, and the lower fulcrum 3 is arranged at the corresponding lower part inside the switch body 1. The upper end of the fork passes through the upper through hole, and the lower end passes through the lower through hole. Both the upper through hole and the lower through hole are polygonal inner through holes. Both the upper and lower ends of the fork 7 are arranged as polygonal cylinders adapted to the polygonal inner through holes to ensure that the upper and lower ends of the fork do not undergo overall deflection when passing through the polygonal inner through holes on the switch body 1. The fork 7 can move linearly up and down in the switch body 1. Upper and lower limit protrusions are provided on the fork 7 to limit the movement stroke of the moving contact 5. The lower limit protrusion is supported on the switch body 1. A moving contact 5 is arranged on the fork 7. Here, the moving contact 5 is an example of a shrapnel-type moving contact 4 (as shown in Figure 2 ), and a flipping groove is provided on the shrapnel-type moving contact 4, and is used for the closing and opening of the switch device. Without any external force pushing the fork 7, the monostable switch always remains in the closed state.

[0034] Embodiment 3: As shown in Figure 1As shown in FIGS. 1 - 17, a two - stage switch device includes a two - stage device, a bracket 14, a support spring 12, and a monostable switch; the two - stage device includes a starting bolt 8, a return spring 11, a stopping bolt 9, and a stopping nut seat 10; the stopping bolt 9 is screwed into the stopping nut seat 10, the stopping bolt 9 is a hollow bolt, the starting bolt 8 is screwed with the stopping bolt 9 and can be rotated up and down in the hollow of the stopping bolt 9 for adjustment; the return spring 11 is arranged between the starting bolt 8 and the fork 7, its upper part abuts against the starting bolt 8, and its lower part abuts against the fork 7; the stopping nut seat 10 is rigidly connected to the bracket 14, a guide rail structure is arranged on the bracket 14, the switch body 1 is arranged in the middle of the bracket 14, its upper part abuts against the bottom of the stopping bolt 9, and its lower part abuts against the support spring 12, and it can move freely up and down along the bracket 14 between the stopping nut seat 10 and the support spring 12, and both ends of the support spring 12 are respectively supported between the switch body 1 and the bracket 14; a control method for a two - stage switch device: set the elastic force of the return spring 11 to be greater than the flipping force of the moving contact 5; set the moving contact 5 to be a spring - type moving contact, the moving contact 5 is composed of a contact spring 19 and a moving contact piece 6, the moving contact piece 6 includes silver contacts symmetrically arranged at both ends; the moving contact piece 6 is sleeved on the fork 7 and can move freely, the contact spring 19 is arranged on the fork 7, and both ends of it are respectively sleeved on the middle protrusions of the moving contact piece 6; when the fork 7 is not subjected to an external P - direction thrust, due to the elastic force of the return spring 11, the moving contact 5 and the static contact 2 in the monostable switch are in a contact state; when the fork 7 is subjected to an external P - direction thrust and moves upward, it simultaneously pushes the monostable switch to compress the return spring 11 and move upward and drives the static contact 2 to move upward; when the switch body 1 abuts against the bottom of the stopping bolt 9, the monostable switch and the return spring 11 stop moving, and at this time the static contact 2 acts as a fulcrum; the fork 7 continues to move upward, after the moving contact 5 crosses the balance point of the static contact 2, it flips, and the moving contact 5 and the static contact 2 are in a separated state, and at this time, adjust the stopping bolt 9 to a suitable stopping position;When the thrust received by the shift fork 7 weakens, under the action of the return spring 11, the monostable switch moves downward. When the return spring 11 and the support spring 12 reach the elastic balance point, the monostable switch stops moving. At this time, due to the support of the lower fulcrum 3, as long as the external P-direction thrust continues to weaken, under the elastic force of the return spring 11 and the support of the lower fulcrum 3, the shift fork 7 will continue to push the center of the moving contact downward. When passing the balance point of the lower fulcrum 3, the moving contact 5 flips, and the moving contact 5 and the static contact 2 in the monostable switch resume the contact state. At this time, adjust the starting bolt 8 to the appropriate starting position.;

[0035] Embodiment 4: As Figure 1 —9, Figure 12 —17, Figure 18As shown in FIGS. 18 and 19, a two-tone switch device includes a two-tone device, a bracket 14, a support spring 12, and a monostable switch; the two-tone device includes a starting bolt 8, a return spring 11, a stopping bolt 9, and a stopping nut seat 10; the stopping bolt 9 is screwed into the stopping nut seat 10, the stopping bolt 9 is a hollow bolt, the starting bolt 8 is screwed with the stopping bolt 9 and can be rotated up and down in the hollow of the stopping bolt 9 for adjustment; the return spring 11 is arranged between the starting bolt 8 and the fork 7, its upper part abuts against the lower part of the starting bolt 8, and the lower part abuts against the fork 7; the stopping nut seat 10 is rigidly connected to the bracket 14, a guide rail structure is arranged on the bracket 14, the switch body 1 is arranged in the middle of the bracket 14, its upper part abuts against the bottom of the stopping bolt 9, and the lower part abuts against the support spring 12 and can move freely up and down along the bracket 14 between the stopping nut seat 10 and the support spring 12, and both ends of the support spring 12 are respectively supported between the switch body 1 and the bracket 14; a control method for a two-tone switch device: set the elastic force of the return spring 11 to be greater than the flipping force of the moving contact 5; set the moving contact 5 as a leaf spring type moving contact 4, the contact spring in the moving contact 5 is a leaf spring, the moving contact 4 includes silver contacts symmetrically arranged at both ends of the leaf spring, and a flipping groove is arranged on the leaf spring of the moving contact 4; when the fork 7 is not subjected to an external P-directional thrust, due to the elastic force of the return spring 11, the moving contact 4 and the static contact 2 in the monostable switch are in a contact state; when the fork 7 is subjected to an external P-directional thrust and moves upward, it simultaneously pushes the monostable switch to compress the return spring 11 and move upward and drives the static contact 2 to move upward; after the switch body 1 abuts against the bottom of the stopping bolt 9, the monostable switch and the return spring 11 stop moving, and at this time the static contact 2 plays a fulcrum role; the fork 7 continues to move upward, and after the moving contact 4 passes the balance point of the static contact 2, it flips, and the moving contact 4 and the static contact 2 are in a separated state, and at this time adjust the stopping bolt 9 to a suitable stopping position; when the thrust received by the fork 7 weakens, under the action of the return spring 11, the monostable switch moves downward, and when the return spring 11 and the support spring 12 reach the elastic force balance point, the monostable switch stops moving. At this time, due to the support of the lower fulcrum, as long as the external P-directional thrust continues to weaken, under the elastic force of the return spring 11 and the support of the lower fulcrum, the fork 7 will continue to push the center of the moving contact downward. When passing the balance point of the lower fulcrum 3, the moving contact 4 flips, and the moving contact 4 and the static contact 2 in the monostable switch resume the contact state, and at this time adjust the starting bolt 8 to a suitable starting position.

[0036] Example 5: As Figure 1 -9, Figure 12 -17, Figure 20As shown in Figure 21, a dual-tuning pressure automatic switch includes a dual-tuning switch device, a base 16, a pressure ring 15, a test spring 13, a thrust rod 17, and a sealing elastic pad 18. The base 16 is hermetically connected to the bracket 14. Inside the base 16, there are a pressure ring 15, an elastic sealing pad 13, and a thrust rod 17. There are protrusions on the inner periphery of the bottom of the pressure ring 15. A test spring 13 is sleeved on the thrust rod 17. The thrust rod 17 is T-shaped, with its upper part being a rod portion and having a protrusion at the bottom. The test spring 13 is supported between the protrusion at the bottom of the thrust rod 17 and the bracket 14. The lower end face of the protrusion at the bottom of the thrust rod 17 rests on the protrusion provided on the inner periphery of the bottom of the pressure ring 15. A pressure ring 15 is provided between the bracket 14 and the base 16. The pressure ring 15 is fixed between the bracket and the base 16. The lower end face of the pressure ring 15 abuts against the elastic sealing pad 18, fixing the elastic sealing pad 18 on the base 16. The elastic sealing pad 18 is seated on the base 16 and fixed between the base 16 and the pressure ring 15, with one side abutting against the base 16 and the other side abutting against the pressure ring 15. The upper end of the thrust rod 17 passes through the bracket 14 and faces the lower end face of the fork 7, and the lower end abuts against the upper end face of the elastic sealing pad 18. There is an adjustment gap between the lower end face of the fork 7 and the upper end face of the thrust rod 17. Control method of the dual-tuning pressure automatic switch: Set the elastic force of the starting spring 8 to be greater than the flipping force of the moving contact 5. When liquid or gas enters the inlet of the base along the P direction, in the case of zero or very weak pressure, the moving contact 5 and the static contact 2 in the monostable switch are in a contact state, and the dual-tuning pressure automatic switch is in a closed state. When the pressure gradually increases, it pushes the thrust rod 17 to move upward and compress the test spring 13, and at the same time pushes the fork 7 to move upward, thereby pushing the monostable switch to compress the starting spring 8 and move upward, and driving the static contact 2 to move upward. After the switch body 1 abuts against the bottom of the stop bolt 9, the monostable switch and the starting spring 8 stop moving. At this time, the static contact 2 acts as a fulcrum, and the fork 7 continues to move upward. The moving contact 5 flips after exceeding the fulcrum balance point. The moving contact 5 and the static contact 2 in the monostable switch are in a separated state, and the dual-tuning pressure automatic switch is in an open state. Adjust the stop bolt to an appropriate stop position;When the pressure of the liquid or gas weakens, the thrust force received by the shift fork 7 weakens. Under the action of the return spring 11, the monostable switch is pushed downward. After reaching the elastic force balance point of the return spring 11 and the support spring 12, the monostable switch stops moving. At this time, the lower fulcrum 3 plays a supporting role, and the shift fork 7 continues to move downward under the elastic force of the return spring 11. At the same time, the thrust rod 17 also moves downward correspondingly under the elastic force of the test spring 13. After the moving contact 5 passes the balance point of the lower fulcrum 2, it flips, and the moving contact 5 resumes contact with the static contact 2. The dual-adjustment type pressure automatic switch then enters the on state; at this time, just adjust the starting bolt 8 to the appropriate starting position.

[0037] It can be understood that for those skilled in the art, equivalent replacements or changes to the technical solutions and inventive concepts of the present invention should fall within the protection scope of the appended claims of the present invention.

Claims

1. A bistable switch device, comprising a bistable device, a bracket, a support spring, and a monostable switch, Characterized in that: The monostable switch includes a switch body and a switch device. The switch device is arranged in the switch body. The switch device includes a fork, a static contact, a moving contact, and a lower fulcrum. The static contact is arranged at the upper part inside the switch body, and the lower fulcrum is arranged at the lower part inside the switch body; A guiding structure is arranged on the switch body so that the fork can move linearly up and down in the switch body; A moving contact is arranged on the fork for closing and disconnecting the switch device; The bistable device includes a starting bolt, a return spring, a stopping bolt, and a stopping nut seat; The stopping bolt is screwed inside the stopping nut seat. The stopping bolt is a hollow bolt. The starting bolt is screwed with the stopping bolt and can rotate up and down in the hollow of the stopping bolt for adjustment; The return spring is arranged between the starting bolt and the fork, with its upper part abutted against the starting bolt and its lower part abutted against the fork; The stopping nut seat is rigidly connected to the bracket. A guide rail structure is arranged on the bracket. The switch body is arranged in the middle of the bracket, and its lower part abuts against the support spring and can move freely up and down between the stopping nut seat and the support spring along the bracket; Both ends of the support spring are respectively supported between the switch body and the bracket; The control method of the bistable switch device includes the following steps: 1). Set the elastic force of the return spring to be greater than the flipping force of the moving contact; 2). When the fork is not subjected to an external P-directional thrust, due to the elastic force of the return spring, the moving contact and the static contact in the monostable switch are in a contact state; 3). When the fork moves upward under the action of an external P-directional thrust, it simultaneously pushes the monostable switch to compress the return spring and move upward, driving the static contact to move upward; After the switch body abuts against the bottom of the stopping bolt, the monostable switch stops moving. At this time, the static contact acts as a fulcrum; The fork continues to move upward. After the moving contact crosses the balance point of the static contact, it flips, and the moving contact and the static contact are in a separated state. At this time, adjust the stopping bolt to a suitable stopping position; 4). When the thrust received by the fork weakens, under the action of the return spring, the monostable switch moves downward. When the return spring and the support spring reach the elastic force balance point, the monostable switch stops moving. At this time, due to the support of the lower fulcrum, as long as the external P-directional thrust continues to weaken, under the elastic force of the return spring and the support of the lower fulcrum, the fork will continue to push the center of the moving contact downward. When crossing the balance point of the lower fulcrum, the moving contact flips, and the moving contact and the static contact in the monostable switch resume the contact state. At this time, adjust the starting bolt to a suitable starting position.

2. A dual-tuning pressure automatic switch, comprising a dual-tuning switch device as described in claim 1, a base, a pressure ring, a test spring, a thrust rod, and a sealing elastic pad. Characterized in that: The base is hermetically connected to the bracket. A pressure ring, an elastic sealing pad, and a thrust rod are arranged inside the base. A protrusion is provided on the inner periphery of the bottom of the pressure ring. A test spring is sleeved on the thrust rod. The thrust rod is T-shaped, with its upper part being a rod portion and a protrusion being provided at the bottom. The test spring is supported between the bottom protrusion of the thrust rod and the bracket. A pressure ring is arranged between the bracket and the base. The pressure ring is fixed between the bracket and the base. The lower end surface of the pressure ring abuts against the elastic sealing pad, fixing the elastic sealing pad on the base. The elastic sealing pad is located on the base and is supported between the base and the pressure ring, with one side abutting against the base and the other side abutting against the pressure ring. The upper end of the thrust rod passes through the bracket and faces the lower end surface of the fork, and the lower end abuts against the upper end surface of the elastic sealing pad. An adjustment gap is provided between the lower end surface of the fork and the upper end surface of the thrust rod. The control method of the dual-tuning pressure automatic switch includes the following steps: 1). Set the elastic force of the return spring to be greater than the flipping force of the moving contact. 2). When liquid or gas enters the inlet of the base along the P direction, in the case of zero or very weak pressure, the moving contact and the static contact in the monostable switch are in a contact state, and the dual-tuning pressure automatic switch is in a connected state. 3). When the pressure gradually increases, it pushes the thrust rod to move upward and compress the test spring, and at the same time pushes the fork to move upward, thereby pushing the monostable switch to compress the return spring and move upward, and driving the static contact to move upward. After the switch body abuts against the bottom of the stop bolt, the monostable switch and the return spring stop moving. At this time, the static contact acts as a fulcrum, the fork continues to move upward, and the moving contact flips after exceeding the fulcrum balance point. The moving contact and the static contact in the monostable switch are in a separated state, and the dual-tuning pressure automatic switch is in a disconnected state. Adjust the stop bolt to an appropriate stop position. 4). When the pressure of the liquid or gas weakens, the thrust force received by the fork weakens. Under the action of the reset spring, the monostable switch is pushed downward. After reaching the elastic force balance point of the reset spring and the support spring, the monostable switch stops moving. At this time, the lower fulcrum plays a supporting role, and the fork continues to move downward under the elastic force of the reset spring. At the same time, the thrust rod also moves downward correspondingly under the elastic force of the test spring. After the moving contact flips over the balance point of the lower fulcrum, the moving contact and the static contact resume the contact state, and the dual-adjustable pressure automatic switch then enters the on state; at this time, adjust the starting bolt to the appropriate starting position.

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