Liquid level height maintaining device

Abstract

The invention relates to the field of liquid level height control, in particular to a liquid level height maintaining device which comprises a floating body, a connecting rod, a conductive sleeve, a liquid conveying pipeline, a liquid conveying valve, a valve control motor, a transmission gear, a rack, a valve control circuit and the like. Through the contact condition of the upper conducting rod body, the lower conducting rod body and the conducting sleeve, the valve control circuit controls the valve control motor to drive the infusion valve to be opened and closed, and various related structures and circuit settings are further achieved. The liquid level height of liquid can be effectively maintained, opening and closing of the infusion valve are accurately controlled through cooperative work of all the components, and it is ensured that the liquid level is within a proper height range.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid level control, and in particular to a liquid level maintaining device. Background Art

[0002] Liquids are widely used in many industrial production and daily life scenarios, and precise control of liquid levels is of great significance. For example, in chemical production, the appropriate liquid level in the reactor is related to the adequacy and safety of the reaction; in the water supply system, the stability of the liquid level in the water tank ensures the normal water supply. Accurately maintaining the liquid level can improve production efficiency, ensure product quality, and enhance the stability of equipment operation. Therefore, liquid level maintenance technology has always been a focus of research and attention in related fields.

[0003] Previous technologies have employed a variety of methods to maintain liquid levels. First, manually observing a level gauge regularly and manually operating a valve based on the observed results to adjust the input or output of liquid. This requires frequent on-site visits to check the liquid level and, based on experience, determine whether the valve should be opened or closed. Second, electronic sensors combined with solenoid valves can be used. These sensors monitor the liquid level in real time and transmit signals to a control system, which then controls the opening and closing of the solenoid valve to regulate the flow of liquid.

[0004] However, these existing technologies have significant drawbacks. Manual operation is not only labor-intensive and time-consuming, but also difficult to accurately maintain the liquid level due to subjective judgment and operational errors, making it prone to excessively high or low levels. Electronic sensors combined with solenoid valves are expensive, and electronic components are prone to failure in harsh environments, compromising the reliability of maintaining the liquid level. Summary of the Invention

[0005] In response to the defects in the prior art, the purpose of the present invention is to provide a liquid level maintaining device that can automatically infuse liquid after the liquid level drops to the minimum limit, and automatically stop infusing liquid after the liquid level rises to the maximum limit, thereby maintaining a stable liquid level.

[0006] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A liquid level maintenance device includes a float, a connecting rod, a conductive sleeve, an infusion pipeline, an infusion valve, a valve control motor, a transmission gear, a rack and a valve control circuit, wherein

[0008] The float is disposed in the liquid;

[0009] The conductive sleeve is fixedly arranged;

[0010] The connecting rod is vertically slidably arranged in the conductive sleeve. The connecting rod comprises an upper conductive rod body, an upper insulating rod body, a lower conductive rod body and a lower insulating rod body from top to bottom. The lower insulating rod body is fixedly arranged on the floating body.

[0011] The liquid outlet of the infusion pipeline is located above the liquid surface, and the infusion valve is arranged on the infusion pipeline;

[0012] The valve control motor is fixedly arranged, the transmission gear is connected to the rotating shaft of the valve control motor, the rack is meshed with the transmission gear, and the rack is transmission-connected to the infusion valve;

[0013] The valve control circuit is electrically connected to the valve control motor, the upper conductive rod, the lower conductive rod and the conductive sleeve; when the upper conductive rod contacts the conductive sleeve, the control circuit controls the valve control motor to drive the infusion valve to open; when the lower conductive rod contacts the conductive sleeve, the control circuit controls the valve control motor to drive the infusion valve to close.

[0014] Optionally, the valve control circuit is a PLC controller or a single-chip controller.

[0015] Optionally, the valve control circuit includes a power supply, an infusion switch, a first normally closed spring switch, a second normally closed spring switch, a first electromagnet, a second electromagnet, a first protective resistor, a second protective resistor, a third normally closed spring switch, and a fourth normally closed spring switch; wherein

[0016] The positive electrode of the power supply is electrically connected to the infusion switch and the conductive sleeve;

[0017] The upper conductive rod, the valve control motor, the second protective resistor, the fourth normally closed spring switch, the first electromagnet, the second normally closed spring switch and the negative electrode of the power supply are electrically connected;

[0018] The valve control motor, the second electromagnet, the third normally closed spring switch and the lower conductive rod are electrically connected;

[0019] The upper conductive rod, the first protective resistor, the third normally closed spring switch and the negative electrode of the power supply are electrically connected;

[0020] The first electromagnet is arranged opposite to the third normally closed spring switch; the second electromagnet is arranged opposite to the fourth normally closed spring switch.

[0021] Optionally, an insulating lever is provided on the rack, the first normally closed spring switch and the second normally closed spring switch are arranged at intervals, and the insulating lever is provided between the first normally closed spring switch and the second normally closed spring switch.

[0022] Optionally, the liquid level maintaining device further includes a support seat and an adjusting rod, the support seat is fixedly arranged, the adjusting rod is horizontally slidably arranged on the support group, and the conductive sleeve is fixedly connected to the adjusting rod.

[0023] Optionally, the valve control motor is a self-locking motor.

[0024] Optionally, a plurality of pin holes are formed on the lower insulating rod from top to bottom, the lower insulating rod is inserted in the middle of the float, and the upper and lower ends of the float are fixed by pins inserted in the pin holes.

[0025] Optionally, the float is a float ball.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. It can accurately maintain the liquid level, solving the problem of limited manual control. The float drives the connecting rod to slide as the liquid level rises and falls, causing the upper and lower conductive rods to contact the conductive sleeve, thereby controlling the opening and closing of the infusion valve and achieving precise adjustment of the liquid level.

[0028] 2. Save manpower and time, avoid frequent manual observation and operation, overcome the defects of manual operation that consumes a lot of manpower and time, and automatically complete the work of maintaining the liquid level;

[0029] 3. Reduce equipment costs and improve reliability. Compared with the method of combining electronic sensors with solenoid valves, this device is cheaper and does not have the problem of electronic components being prone to failure in harsh environments, thus solving the problems of high equipment cost and low reliability of this method. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0031] Figure 1 It is a structural schematic diagram of the liquid level maintaining device of the present invention;

[0032] Figure 2 A circuit diagram for controlling the opening of an infusion valve according to the present invention;

[0033] Figure 3 This is a circuit diagram for controlling the closing of an infusion valve according to the present invention.

[0034] In the figure: 1. Float; 2. Connecting rod; 3. Conductive sleeve; 4. Infusion pipe; 5. Infusion valve; 6. Valve control motor; 7. Transmission gear; 8. Rack; 9. Power supply; 10. Infusion switch; 11. First normally closed spring switch; 12. Second normally closed spring switch; 13. First electromagnet; 14. Second electromagnet; 15. First protective resistor; 16. Second protective resistor; 17. Third normally closed spring switch; 18. Fourth normally closed spring switch; 19. Insulating lever; 20. Support seat; 21. Adjusting rod; 22. Upper conductive rod; 23. Upper insulating rod; 24. Lower conductive rod; 25. Lower insulating rod. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0036] Example 1

[0037] Combine Figure 1 As shown, an embodiment of the present invention discloses a liquid level maintaining device, including a float 1, a connecting rod 2, a conductive sleeve 3, an infusion pipe 4, an infusion valve 5, a valve control motor 6, a transmission gear 7, a rack 8 and a valve control circuit, wherein the float 1 is arranged in the liquid and will move up and down with the rise and fall of the liquid level; the conductive sleeve 3 is fixedly arranged; the connecting rod 2 is vertically slidably arranged in the conductive sleeve 3, and the connecting rod 2 can make up and down linear motion along the conductive sleeve 3, thereby achieving the beneficial effect of driving the connecting rod 2 to slide in the conductive sleeve 3 through the change of the liquid level. This is because the float 1 is connected to the connecting rod 2, and the rise and fall of the liquid level will directly cause the rise and fall of the float 1, thereby driving the connecting rod 2 to slide in the conductive sleeve 3.

[0038] The liquid outlet of the infusion pipe 4 is located above the liquid surface, which facilitates the liquid to flow into the container. The infusion valve 5 is arranged on the infusion pipe 4 to control the on and off of the liquid in the infusion pipe 4; the valve control motor 6 is fixedly arranged, the transmission gear 7 is connected to the rotating shaft of the valve control motor 6, the rack 8 is meshed with the transmission gear 7, and the rack 8 is connected to the infusion valve 5; when the valve control motor 6 rotates, the meshing transmission of the transmission gear 7 and the rack 8 can convert the rotational motion into linear motion, thereby driving the opening and closing of the infusion valve 5.

[0039] The valve control circuit is electrically connected to the valve control motor 6, the upper conductive rod, the lower conductive rod, and the conductive sleeve 3. This circuit controls the operation of the valve control motor 6 based on the contact between the conductive rod and the conductive sleeve 3, thereby controlling the opening and closing of the infusion valve 5 and ultimately maintaining the liquid level. For example, when the upper conductive rod contacts the conductive sleeve 3, the control circuit controls the valve control motor 6 to open the infusion valve 5; when the lower conductive rod contacts the conductive sleeve 3, the control circuit controls the valve control motor 6 to close the infusion valve 5.

[0040] Specifically, the float 1 includes a float or other objects with sufficient buoyancy, such as a cylindrical float. The float is generally made of hollow plastic material, which has low density, high buoyancy and corrosion resistance. It can float well on the liquid surface and will not be corroded by the liquid even after long-term use. The shape of the float is usually spherical, so that it encounters less resistance in the liquid and can move up and down more flexibly with the fluctuation of the liquid level. The cylindrical float can be made of metal material and wrapped with an anti-corrosion coating on the outside. It is suitable for maintaining the liquid level of some large containers because it has a large surface area and can better adapt to large-scale changes in the liquid level. The float 1 is set in the liquid and can float stably on the liquid surface and move synchronously with the rise or fall of the liquid level.

[0041] Specifically, the connecting rod 2 comprises, from top to bottom, an upper conductive rod, an upper insulating rod, a lower conductive rod, and a lower insulating rod. The lower insulating rod is fixed to the buoy 1. The upper conductive rod is generally made of copper, which has excellent conductivity and ensures smooth current transmission. It is typically cylindrical in shape with a smooth surface to reduce friction when sliding within the conductive sleeve 3. The upper insulating rod can be made of rubber, which has excellent insulation properties and effectively isolates current, preventing leakage. The upper insulating rod is tightly connected to the upper conductive rod and can be fixed together by sleeve or adhesive to form a single unit. The lower conductive rod is also made of copper and has the same conductivity and structural characteristics as the upper conductive rod. The lower insulating rod is made of plastic, which is hard and has excellent insulation properties. The lower insulating rod can be fixed to the buoy 1 by threading, screwing the lower insulating rod into a specific screw hole in the buoy 1 to ensure a secure connection. The connecting rod 2 as a whole performs vertical sliding motion in the conductive sleeve 3 , thereby realizing the function of moving up and down in the conductive sleeve 3 as the floating body 1 rises and falls.

[0042] Specifically, the conductive sleeve 3 is typically made of metal, such as stainless steel. Stainless steel not only offers excellent conductivity but also strong corrosion resistance, making it suitable for various liquid environments. The inner wall of the conductive sleeve 3 is polished to reduce friction with the connecting rod 2, allowing the connecting rod 2 to slide more smoothly within the sleeve. The conductive sleeve 3 is secured in place by a bracket or other structure, ensuring its stability and preventing it from shaking or shifting due to external factors.

[0043] Specifically, the infusion pipe 4 can be made of plastic pipes or metal pipes. Plastic pipes, such as PVC pipes, have the advantages of light weight, low price, and corrosion resistance; metal pipes, such as steel pipes, have the characteristics of high strength and good pressure resistance. The liquid outlet of the infusion pipe 4 is located above the liquid surface to ensure that the liquid can flow smoothly into the container. The infusion valve 5 can be a ball valve or a gate valve. In this embodiment, a ball valve is used. The ball valve has a fast switching speed and good sealing performance; the gate valve has a large flow adjustment range and can more accurately control the flow of the liquid. The infusion valve 5 of this embodiment is installed on the infusion pipe 4. A gear is fixedly installed at one end of the ball valve. The ball valve is engaged with the rack 8 through the gear, and the control of the liquid on and off in the infusion pipe 4 is achieved through cooperation with the valve control motor 6.

[0044] Furthermore, the valve control motor 6 of this embodiment is a self-locking motor. After the self-locking motor stops rotating, it can automatically lock its position to prevent malfunction due to external interference. It usually adopts a permanent magnet DC motor, which has the advantages of small size, high efficiency, and good speed regulation performance. The valve control motor 6 is fixed by means of bolts or the like to ensure the accuracy and stability of its position. The transmission gear 7 and the rotating shaft of the valve control motor 6 are connected by a key to ensure synchronous rotation between the two. The transmission gear 7 is generally made of alloy steel and has high strength and wear resistance. The rack 8 is meshed with the transmission gear 7. The rack 8 is also made of alloy steel. Its tooth shape design must match the tooth shape of the transmission gear 7 to ensure the smoothness and accuracy of the transmission.

[0045] Furthermore, the valve control circuit of this embodiment is a PLC controller or a single-chip controller. The PLC controller has the advantages of powerful functions, high reliability, and flexible programming, and is suitable for some liquid level maintenance systems with high control requirements and relatively complex. The single-chip controller has the characteristics of low cost, small size, and low power consumption, and is suitable for some small and simple liquid level maintenance devices. The valve control circuit is electrically connected to the valve control motor 6, the upper conductive rod, the lower conductive rod, and the conductive sleeve 3 through wires. When the upper conductive rod contacts the conductive sleeve 3, the control circuit controls the valve control motor 6 to drive the infusion valve 5 to open; when the lower conductive rod contacts the conductive sleeve 3, the control circuit controls the valve control motor 6 to drive the infusion valve 5 to close.

[0046] The operating principle of this embodiment is as follows: the liquid level maintenance device, through a float 1, drives a connecting rod 2 to slide within a conductive sleeve 3 as the liquid level rises and falls. The contact between the conductive rod and the conductive sleeve 3 triggers the valve control circuit, which in turn controls the valve control motor 6 to open and close the infusion valve 5. Compared with traditional manual operation, this method avoids significant manpower investment and human error, and can more accurately maintain the liquid level. It also offers higher control accuracy and is suitable for applications with high liquid level requirements. Compared with the combination of electronic sensors and solenoid valves, this method reduces equipment costs and the risk of electronic component failure in harsh environments, thereby improving the reliability of liquid level maintenance.

[0047] Example 2

[0048] Combine Figures 1 to 3 As shown, as another embodiment of the present invention, different from the first embodiment, the valve control circuit of this embodiment includes a power supply 9, an infusion switch 10, a first normally closed spring switch 11, a second normally closed spring switch 12, a first electromagnet 13, a second electromagnet 14, a first protective resistor 15, a second protective resistor 16, a third normally closed spring switch 17, and a fourth normally closed spring switch 18; wherein the positive pole of the power supply 9 is electrically connected to the infusion switch 10 and the conductive sleeve 3; the upper conductive rod, the valve control motor 6, the second protective resistor 16, the fourth normally closed spring switch 18, the first electromagnet 13, the second normally closed spring switch 12 and the negative pole of the power supply 9 are electrically connected; the valve control motor 6, the second electromagnet 14, the third normally closed spring switch 17 and the lower conductive rod are electrically connected; the upper conductive rod, the first protective resistor 15, the third normally closed spring switch 17 and the negative pole of the power supply 9 are electrically connected; the first electromagnet 13 and the third normally closed spring switch 17 are arranged opposite each other; and the second electromagnet 14 and the fourth normally closed spring switch 18 are arranged opposite each other. It is easy to understand that the connection sequence of each component can be adjusted according to actual needs, and this embodiment does not impose any specific limitation.

[0049] In addition, an insulating lever 19 is provided on the rack 8. The first normally closed spring switch 11 and the second normally closed spring switch 12 are spaced apart, with the insulating lever 19 positioned between the first normally closed spring switch 11 and the second normally closed spring switch 12. When the rack 8 moves, the insulating lever 19 moves with the rack 8. When the insulating lever 19 contacts the first normally closed spring switch 11 or the second normally closed spring switch 12, the state of the spring switch is changed, thereby affecting the on / off state of the circuit.

[0050] The specific control principle of this embodiment is as follows: closing the infusion switch 10 starts the entire circuit. At this time, the water level has not dropped, and the insulating lever 19 touches the first normally closed spring switch 11 to disconnect it; when the water level drops, the upper conductive rod contacts the conductive sleeve 3, and the branch of the positive pole of the power supply 9, the infusion switch 10, the conductive sleeve 3, the upper conductive rod, the valve control motor 6, the second protective resistor 16, the fourth normally closed spring switch 18, the first electromagnet 13, the second normally closed spring switch 12 and the negative pole of the power supply 9 is connected; no current is generated in the branch connecting the valve control motor 6, the second electromagnet 14, the first normally closed spring switch 11 and the lower conductive rod; and because the first electromagnet 13 generates magnetic force, the third normally closed spring switch 17 is disconnected, and the upper conductive rod, the first protective resistor 15, the third normally closed spring switch 17 and the power supply 9 No current is generated in the branch connected to the negative pole. At this time, the valve control motor 6 rotates forward to drive the rack 8 to move toward the direction close to the second normally closed spring switch 12, and the infusion valve 5 gradually opens; when the infusion valve 5 is completely opened, the insulating lever 19 touches the second normally closed spring switch 12 to disconnect it, and the branch connected to the positive pole of the power supply 9, the infusion switch 10, the conductive sleeve 3, the upper conductive rod body, the valve control motor 6, the second protective resistor 16, the fourth normally closed spring switch 18, the first electromagnet 13, the second normally closed spring switch 12 and the negative pole of the power supply 9 loses current. The branch connected to the upper conductive rod body, the first protective resistor 15, the third normally closed spring switch 17 and the negative pole of the power supply 9 generates current to form a protection circuit, and the valve control motor 6 stops rotating and self-locks; at this time, liquid can be transported into the container through the infusion pipe 4 to raise the liquid level.

[0051] When the water level rises, the lower conductive rod contacts the conductive sleeve 3, and a current is generated in the branch connecting the positive electrode of the power supply 9, the infusion switch 10, the conductive sleeve 3, the lower conductive rod, the first normally closed spring switch 11, the second electromagnet 14, the valve control motor 6, the first protective resistor 15, the third normally closed spring switch 17, and the negative electrode of the power supply 9, forming a circuit. However, the second normally closed spring switch 12 is also disconnected by the insulating lever 19, so no current is generated in the branch connecting the second protective resistor 16, the fourth normally closed spring switch 18, the first electromagnet 13, the second normally closed spring switch 12, and the negative electrode of the power supply 9. The current flowing through the valve control motor 6 is opposite to that when the liquid level drops, so the valve control motor 6 reverses and drives the rack 8 toward the first normally closed spring switch 11, gradually closing the infusion valve 5. When the infusion valve 5 is completely closed, the insulating lever 19 contacts the first normally closed spring switch 11, disconnecting it, and the valve control motor 6 stops rotating and self-locks. At this time, the infusion pipeline 4 stops conveying liquid into the container. It's worth noting that when valve control motor 6 reverses and drives rack 8 toward first normally closed spring switch 11, although insulating lever 19 moves away from second normally closed spring switch 12, the magnetic force generated by second electromagnet 14 disconnects fourth normally closed spring switch 18. Consequently, no current flows through the circuit connecting second protective resistor 16, fourth normally closed spring switch 18, first electromagnet 13, second normally closed spring switch 12, and the negative terminal of power supply 9. When the liquid level drops again, the aforementioned process repeats, achieving automatic liquid level control.

[0052] Example 3

[0053] Combine Figures 1 to 3 As shown, as another embodiment of the present invention, different from the first embodiment, the liquid level maintaining device of this embodiment also includes a support seat 20 and an adjusting rod 21, the support seat 20 is fixedly arranged, the adjusting rod 21 is horizontally slidably arranged on the support group, and the conductive sleeve 3 is fixedly connected to the adjusting rod 21.

[0054] Furthermore, a plurality of pin holes are formed on the lower insulating rod from top to bottom. The lower insulating rod is inserted in the middle of the float 1 , and the upper and lower ends of the float 1 are fixed by pins inserted in the pin holes.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] 1. It can accurately maintain the liquid level, solving the problem of limited manual control. The float 1 drives the connecting rod 2 to slide as the liquid level rises and falls, causing the upper and lower conductive rods to contact the conductive sleeve 3, thereby controlling the opening and closing of the infusion valve 5, achieving precise adjustment of the liquid level.

[0057] 2. Save manpower and time, avoid frequent manual observation and operation, overcome the defects of manual operation that consumes a lot of manpower and time, and automatically complete the work of maintaining the liquid level;

[0058] 3. Reduce equipment costs and improve reliability. Compared with the method of combining electronic sensors with solenoid valves, this device is cheaper and does not have the problem of electronic components being prone to failure in harsh environments, thus solving the problems of high equipment cost and low reliability of this method.

[0059] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0060] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A liquid level maintaining device, characterized in that: It includes a float, a connecting rod, a conductive sleeve, an infusion pipe, an infusion valve, a valve control motor, a transmission gear, a rack and a valve control circuit, wherein The float is disposed in the liquid; The conductive sleeve is fixedly arranged; The connecting rod is vertically slidably arranged in the conductive sleeve, and the connecting rod comprises an upper conductive rod body, an upper insulating rod body, a lower conductive rod body and a lower insulating rod body from top to bottom, and the lower insulating rod body is fixedly arranged on the floating body; The liquid outlet of the infusion pipeline is located above the liquid surface, and the infusion valve is arranged on the infusion pipeline; The valve control motor is fixedly arranged, the transmission gear is connected to the rotating shaft of the valve control motor, the rack is meshed with the transmission gear, and the rack is in transmission connection with the infusion valve; The valve control circuit is electrically connected to the valve control motor, the upper conductive rod, the lower conductive rod and the conductive sleeve; when the upper conductive rod contacts the conductive sleeve, the control circuit controls the valve control motor to drive the infusion valve to open; when the lower conductive rod contacts the conductive sleeve, the control circuit controls the valve control motor to drive the infusion valve to close.

2. The liquid level maintaining device according to claim 1, wherein: The valve control circuit is a PLC controller or a single-chip controller.

3. The liquid level maintaining device according to claim 1, wherein: The valve control circuit includes a power supply, an infusion switch, a first normally closed spring switch, a second normally closed spring switch, a first electromagnet, a second electromagnet, a first protective resistor, a second protective resistor, a third normally closed spring switch, and a fourth normally closed spring switch; wherein The positive electrode of the power supply is electrically connected to the infusion switch and the conductive sleeve; The upper conductive rod, the valve control motor, the second protective resistor, the fourth normally closed spring switch, the first electromagnet, the second normally closed spring switch and the negative electrode of the power supply are electrically connected; The valve control motor, the second electromagnet, the third normally closed spring switch and the lower conductive rod are electrically connected; The upper conductive rod, the first protective resistor, the third normally closed spring switch and the negative electrode of the power supply are electrically connected; The first electromagnet is arranged opposite to the third normally closed spring switch; the second electromagnet is arranged opposite to the fourth normally closed spring switch.

4. The liquid level maintaining device according to claim 3, wherein: An insulating lever is provided on the rack, the first normally closed spring switch and the second normally closed spring switch are arranged at intervals, and the insulating lever is provided between the first normally closed spring switch and the second normally closed spring switch.

5. The liquid level maintaining device according to any one of claims 1 to 4, characterized in that: It also includes a support base and an adjustment rod, the support base is fixedly arranged, the adjustment rod is horizontally slidably arranged on the support group, and the conductive sleeve is fixedly connected to the adjustment rod.

6. The liquid level maintaining device according to any one of claims 1 to 4, characterized in that: The valve control motor is a self-locking motor.

7. The liquid level maintaining device according to any one of claims 1 to 4, characterized in that: The lower insulating rod is formed with a plurality of pin holes from top to bottom. The lower insulating rod is inserted in the middle of the float. The upper and lower ends of the float are fixed by pins inserted in the pin holes.

8. The liquid level maintaining device according to claim 7, wherein: The floating body is a floating ball.

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