CN204346543U - Non-contact type liquid level detecting device - Google Patents

Abstract

The utility model discloses a non-contact liquid level detection device, which comprises: a detection board, at least one sensing unit arranged on the detection board and arranged at intervals, and an The connected control detection unit uses CapSense sensing self-capacitance or mutual capacitance detection technology, and the control detection unit and the sensing unit are combined to form a detection module, and the liquid level information is obtained by detecting the change of the capacitance value. The utility model has the advantages of high detection accuracy, low cost, convenient installation and convenient container cleaning, which can meet most of the requirements for liquid level detection, and is especially suitable for humidifiers, purifiers, water purifiers, coffee machines and other households that need to clean containers. use on electrical appliances.

Description

Non-contact liquid level detection device

technical field

The utility model relates to a non-contact liquid level detection device.

Background technique

As we all know, the liquid level detection method is divided into contact liquid level detection and non-contact liquid level detection. As the name implies, the contact liquid level detection method is that the sensor and the liquid to be detected are in contact with each other. It is relatively simple to see. It is directly inserted into the liquid through the conductive probe or the conductive sheet 6. Using the conductivity of the liquid, as the liquid level rises, the electrode signal also changes accordingly. When the electrode is energized in the liquid, electrolysis will occur. Chemical reaction, when water is electrolyzed, oxygen will be generated, which will easily breed bacteria for a long time. At the same time, the conductive electrode will also be corroded, and a large amount of metal ions will be generated in the liquid. Although the accurate measurement of liquid level force can be improved by adding electrodes, when the structure is installed Leakage prevention devices are also vulnerable to lightning strikes. In addition, contact liquid level detection is not suitable for liquid level detection of various acid-base, flammable, and high-risk liquids. Therefore, people began to turn to research on non-contact liquid level detection.

Non-contact liquid level detection means that the sensor and the liquid to be detected are isolated from each other without direct contact. The traditional non-contact liquid level detection methods mainly include ultrasonic detection, laser detection, Hall devices or reed switches with floats (with Magnet) detection methods, etc. Among them, the ultrasonic detection method and the laser detection method use the reflection principle to detect the liquid level, the cost and installation requirements are high, and there is a certain blind area; and the Hall device or the reed switch cooperates with the float (with a magnet inside) The detection method uses the principle of liquid buoyancy to detect the liquid level, but it has high requirements for structural installation and there is a hidden danger of the float being stuck. As shown in Figure 2, it is a Hall device or a dry reed switch with a float detection structure. The detection device 1 is cylindrical and inserted into the liquid. The float 2 changes along the detection device 1 with the liquid level and is inside There is a magnet 3, and at the same time, the detection device 1 is provided with a plurality of sensors 4 in the height direction. When the signal of the third or fifth sensor disappears, the fourth sensor detects the magnet 3 of the float 2, indicating that the water level is in the fourth grid. To accurately measure the water level, multiple sensors need to be added, and the difficulty of the installation structure is also greatly increased, and it is also necessary to prevent liquid from entering the detection device. At the same time, the sensor 4 uses a high-cost reed switch sensor or Hall sensor, which also leads to a relatively high cost. high. In order to prevent the liquid from entering the detection device, as shown in Figure 3, it is another Hall device or reed switch with a float detection structure, and its multiple sensors 4 are directly arranged outside the container, while inside the container there are The float 2 of the magnet 3 and the float frame 5 that guides the float 2 to move up and down have a relatively simple structure, but when the container needs to be cleaned regularly on some equipment such as air purification, water purification, and humidification, it is easy to clean uncleanly, and there are dead angles, which are not easy to clean. To remove dirt, and to accurately measure the water level, it is also necessary to add multiple sensors, which greatly increases the cost.

Utility model content

The purpose of the utility model is to provide a non-contact liquid level detection device to simplify the structure and realize accurate measurement of the liquid level. cost.

The first technical solution of the utility model is: a non-contact liquid level detection device, which is arranged on the outside of the container, which includes: a detection board, at least one sensing unit arranged on the detection board and arranged at intervals, and a device A control detection unit on the detection board and connected to the output of at least one sensing unit, wherein the control detection unit and the sensing unit are combined to form a detection module, which detects changes in capacitance value to obtain liquid level information.

On the basis of the first technical solution, the following subsidiary technical solutions are further included:

The sensing unit is covered with copper, and there is a gap between two adjacent sensing units.

The distance between the detection board and the container is less than or equal to 10mm, and the copper clad area of the sensing unit is greater than or equal to 10 square millimeters.

When it is a liquid level discontinuous detection device, there is only one sensing unit at the same height of the liquid level;

When it is a liquid level continuous detection device, there are at least two sensing units when the liquid level is at the same height, and the areas of adjacent sensing units are staggered in the vertical direction.

When the sensing unit is at least one, it utilizes an inherent parasitic capacitance between at least one copper pour and the negative pole of the power supply, and detects the liquid level through the capacitance change between the sensing unit and the negative pole of the power supply; or

When there are at least two sensing units, there is an inherent parasitic capacitance between at least two adjacent pieces of copper pouring, one sensing unit transmits a signal, while the other sensing unit receives a signal, and passes the sensing unit The capacitance change between the sensing units is used to detect the liquid level.

The second technical solution of the present invention is: a non-contact liquid level detection device, which is arranged outside the container, and includes: a detection plate extending in the vertical direction to measure the height of the liquid level, at least one The sensing unit, the control detection unit arranged on the detection board and connected to the output of at least one sensing unit, the host computer connected to the output of the control detection unit, the display unit connected to the output of the host computer and displaying the liquid level, and the controller The detection unit provides a power supply of electric power, and a water level controller connected to the output of the host computer and the power supply, wherein the sensing unit detects the change of the capacitance value to obtain the liquid level information.

On the basis of the second technical solution, it further includes the following subsidiary technical solutions:

The sensing unit is covered with copper, and there is a gap between two adjacent sensing units, the distance between the detection board and the container wall is less than or equal to 10mm, and the copper-clad area of the sensing unit is greater than or equal to 10 square millimeters, each The area of the gap is smaller than the area of each copper pour, and the height of each gap is also smaller than the height of each copper pour, so as to realize accurate measurement.

When the sensing unit is at least one, the liquid level is detected by using the self-capacitance existing between at least one copper pour and the negative pole of the power supply, and through the capacitance change between the sensing unit and the negative pole of the power supply; or

When there are at least two sensing units, using the mutual capacitance between at least two adjacent pieces of copper clad copper, one of the sensing units emits a signal, while the other sensing unit receives the signal, and passes through the sensing unit The capacitance change between them is used to detect the liquid level.

A household appliance having the above-mentioned non-contact liquid level detection device, the household appliance is a humidifier, an air purifier, a water purifier, and a coffee machine.

The utility model advantage is:

1) It can be used effectively for a long time in the case of high temperature and poor water quality, prolonging the service life;

2) It can be used for liquid level detection of various acid-base, flammable and high-risk liquids;

3) Insulated from the liquid, not afraid of lightning strikes, and will not have weak electrolytic reactions;

4) Simplify the structure to achieve accurate measurement of the liquid level, which is beneficial to the user's cleaning of the inside of the container and can reduce costs.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described:

Fig. 1 is a structural schematic diagram of contact liquid level detection in the prior art;

Fig. 2 is a structural schematic diagram of a non-contact liquid level detection in the prior art;

Fig. 3 is a structural schematic diagram of another non-contact liquid level detection in the prior art;

Fig. 4 is the structural representation of the first embodiment in the utility model;

Fig. 5 is the structural representation of the discontinuous water level scale detection board in the utility model;

Fig. 6 is the structural representation of continuous water level scale detection board in the utility model;

Fig. 7 is a circuit schematic diagram of the utility model;

Fig. 8 is the distribution schematic diagram of self-capacitance equivalent capacitance in the utility model;

FIG. 9 is a schematic diagram of the distribution of mutual capacitance equivalent capacitance in the present invention.

Fig. 10 is another structural representation in the utility model;

Among them: 1. Detection device; 2. Float; 3. Magnet; 4. Sensor; 5. Float frame; 6. Conductive probe; 10. Container wall; Sensing unit; 22. Control detection unit; 23, 230. Distance; 24. Host computer; 25. Display unit; 26. Power supply; 27. Water level controller.

Detailed ways

Embodiment: As shown in Figures 4-7, the utility model provides a first embodiment of a non-contact liquid level detection device, which is arranged outside the container having a cavity 12 and a container wall 10, and includes: The detection board 20 arranged on the outside of the container wall 10, the plurality of sensing units 21, 210 arranged on the detection board 20 and vertically spaced apart, the gaps 23, 230 between adjacent sensing units 21, the detection board 20 and a control detection unit 22 connected to the output of a plurality of sensing units 21, a host computer 24 connected to the output of the control detection unit 22, a display unit 25 connected to the output of the host computer 24 and displaying the liquid level situation, and a control detection unit 25 connected to the output of the control detection unit 22. The unit 22 provides a power supply 26 for power supply, and a water level controller 27 connected to the output of the host computer 24 and connected to the power supply 26 . Wherein the container wall 10 defines a cavity 12, and the cavity 12 accommodates liquid, and the sensing units 21, 210 detect changes in capacitance values to obtain liquid level information. The detection plate 20 is preferably closely attached to the outer side of the container wall 10, so as to avoid the phenomenon of condensation in the bonding gap when the water temperature changes, which will affect the detection accuracy.

The control and detection unit 22 is a micro-controller with a self-contained detection capacitive sensor, which integrates the touch key detection module into an 8 or 16-bit single-chip microcomputer inside the microprocessor. The IIC communication between the microprocessors transmits the current liquid level information to the upper computer 24 .

The function of the water level controller 27 is to perform some control according to the detected current water level, such as controlling the water pump to automatically add water when the water purifier or the coffee machine is short of water, and turning off the water pump when the water is full; The user performs operations such as adding water.

The sensing units 21, 210 are covered with copper, and the shape is rectangular, trapezoidal, rhombus, ellipse, zigzag, etc. There is a gap 23, 230 between two adjacent sensing units 21, 210, wherein the gap 23, 230 is less than 10 mm And greater than 0.2 mm to ensure that the signal does not interfere.

As shown in Figure 5, when the sensing unit 21 is rectangular, it is used for non-continuous scale water level detection, and there is only one when the liquid level is at the same height. In order to ensure the detection accuracy, the sensing unit 21 requires an area greater than or equal to 10 square millimeters, and Transverse width also can not be too small, and when water overflows sensing unit 21, corresponding sensing unit 21 measures electric capacity at this moment and can produce change (that is, the water level height in the container is within the scope of this sensing unit 21 area distributions ), the height of the liquid level is determined by the magnitude of the capacitance change of the sensing unit 21.

As shown in Figure 6, the distribution of sensing units 210 is similar to a uniform sawtooth shape, which is used for continuous water level scale detection, ensuring that there are always 1 to 2 sensing units 210 intersecting with the parallel surface of the liquid surface at the same water level, and adjacent sensors The areas of the sensing units 210 are staggered in the vertical direction, which fully ensures that when the liquid level changes, there is always a sensing unit 210 that can monitor the change, and can accurately measure the liquid level height in real time.

Preferably, the distance between the detection board 20 and the container wall 10 is less than or equal to 10mm.

Preferably, the above-mentioned non-contact liquid level detection device can be directly applied to household appliances such as humidifiers, air purifiers, water purifiers, and coffee machines.

As shown in Figure 10, the detection board 20 in the above-mentioned embodiment may not be directly attached to the container wall 10, but it is closely attached to the body 30. At the same time, the distance between the body 30 and the container wall 10 should not be too large, generally no more than 10mm, the same can be achieved.

The utility model also provides a second embodiment of a non-contact liquid level detection method, which includes:

First provide a detection board 20 located outside the container, at least one sensing unit 21 disposed on the detection board 20, a control unit 22 disposed on the detection board 20 and connected to the output of the at least one sensing unit 21, and the control unit The upper computer 24 connected to the output of 22, wherein the sensing unit 21 is copper clad;

Then detect the corresponding capacitance value of each sensing unit 21 when there is no liquid in the container, and store the capacitance value data at this time into the control unit 22 as a reference reference capacitance value; as shown in Figure 8, it is a self-capacitance type, etc. Fig. 9 is a schematic diagram of the distribution of effective capacitance. There is an inherent parasitic capacitance Cp (also known as self-capacitance) in one or more sensing units 21 relative to the negative pole of the power supply. Similarly, FIG. 9 is a schematic diagram of the distribution of mutual capacitance equivalent capacitance. There is an inherent parasitic capacitance Cp (also known as mutual capacitance) between the units 21 .

Then put the liquid into the container;

Finally detect the corresponding capacitance value of each sensing unit 21 when there is liquid in the container, and compare it with the reference capacitance value of each sensing unit 21 when there is no liquid before. In the self-capacitance situation shown in FIG. 8 , When the height of the liquid in the cavity 12 reaches the height of the external sensing unit 21, the capacitance will change from Cp to Cp' (that is, Cp'=Cp+Cx), and each sensing unit can be judged by judging the size of the capacitance Cx 21 position state; and in the mutual capacitance situation shown in Figure 9, when the liquid height in the cavity 12 reaches the height of the external sensing unit 21, it will cause the capacitance to change from Cp to Cp' (that is, Cp'=Cp +Cx), one sensing unit 21 transmits a signal, while the other sensing unit 21 receives the signal, controls the detection unit 22 to perform capacitance conversion, and uses the size of the judgment capacitance Cx to judge the position status of each sensing unit 21 . Thus when the control unit 22 detects the capacitance variation of each sensing unit 21, the control unit 22 performs an internal calculation to calculate the current liquid level, and outputs it to the host computer 24 through the control unit 22, and then allows the host computer 24 to perform corresponding control. The water level controller 27 performs water level control and liquid level display, thereby obtaining and displaying the current liquid level.

The utility model detects the change of the capacitance value of the liquid level to detect the liquid level, which has high detection accuracy, low cost, convenient installation, and convenient container cleaning, which can meet most of the requirements for liquid level detection, and is especially suitable for humidifiers, purifiers, and cleaning machines. Water dispenser, coffee machine and other household appliances that need to clean the container.

Of course, the above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present utility model, and its purpose is to allow people familiar with this technology to understand the content of the present utility model and implement it accordingly, and cannot limit the protection scope of the present utility model with this. All equivalent transformations or modifications made according to the spirit of the main technical solutions of the utility model shall fall within the protection scope of the utility model.

Claims (9)

1. A non-contact liquid level detection device, which is arranged on the outside of the container, is characterized in that it comprises: a detection plate (20), at least one sensing unit (21, 210) arranged on the detection plate (20) , and a control detection unit (22) arranged on the detection board (20) and connected to the output of the sensing unit (21, 210), wherein the control detection unit (22) and the sensing unit (21, 210) are combined into a detection module , jointly detect the change of the capacitance value to obtain the liquid level information. 2. A non-contact liquid level detection device according to claim 1, characterized in that: the sensing unit (21, 210) is covered with copper, and the two adjacent sensing units (21, 210) There is a gap (23, 230) between them. 3. A non-contact liquid level detection device according to claim 2, characterized in that: the distance between the detection plate (20) and the container is less than or equal to 10 mm, and the sensing unit (21, 210) Copper covering area is greater than or equal to 10 square millimeters. 4. A non-contact liquid level detection device as claimed in claim 2 or 3, characterized in that: 1) When it is a liquid level discontinuous detection device, there is only one sensing unit (21, 210) at the same height of the liquid level; or 2) When it is a liquid level continuous detection device, there are at least two sensing units (21, 210) at the same height of the liquid level, and the area of adjacent sensing units (21, 210) has a vertical direction. staggered. 5. A non-contact liquid level detection device as claimed in claim 2 or 3, characterized in that: 1) When there is at least one sensing unit (21, 210), and there is an inherent parasitic capacitance between at least one copper clad and the negative pole of the power supply, and through the connection between the sensing unit (21, 210) and the negative pole of the power supply, Capacitance change to detect liquid level; or 2) When there are at least two sensing units (21, 210), there is an inherent parasitic capacitance between at least two adjacent pieces of copper clad copper, one of the sensing units (21, 210) transmits a signal, and Another sensing unit (21, 210) receives the signal, and detects the liquid level through the capacitance change between the sensing units. 6. A non-contact liquid level detection device, which is arranged outside the container, is characterized in that it includes: a detection plate (20) extending vertically to measure the height of the liquid level, at least A sensing unit (21, 210), a control detection unit (22) arranged on the detection board (20) and connected to the output of a plurality of sensing units (21), an upper position connected to the output of the control detection unit (22) machine (24), a display unit (25) that is connected with the output of the upper computer (24) and displays the liquid level situation, a power supply (26) that provides power to the control detection unit (22), and is connected with the output of the upper computer (24) and A water level controller (27) connected to the power supply (26), wherein the sensing unit (21, 210) detects changes in capacitance values to obtain liquid level information. 7. A non-contact liquid level detection device according to claim 6, characterized in that: the sensing unit (21, 210) is covered with copper, and the two adjacent sensing units (21, 210) There is a gap (23, 230) between them, the distance between the detection board (20) and the container wall (10) is less than or equal to 10 mm, and the copper clad area of the sensing unit (21, 210) is greater than or equal to 10 square millimeters. 8. A non-contact liquid level detection device as claimed in claim 6 or 7, characterized in that: 1) When there is at least one sensing unit (21, 210), use the self-capacitance existing between at least one copper clad and the negative pole of the power supply, and use the capacitance change between the sensing unit (21, 210) and the negative pole of the power supply to detect liquid level; or 2) When there are at least two sensing units (21, 210), using the mutual capacitance existing between two adjacent pieces of copper clad, one sensing unit (21, 210) transmits a signal, while the other transmits a signal. The sensing unit (21, 210) receives the signal, and detects the liquid level through the capacitance change between the sensing units. 9. A household appliance with a non-contact liquid level detection device as claimed in claim 1 or 2 or 6 or 7, characterized in that: said household appliance is a humidifier, an air cleaner, a water purifier, a coffee machine .