Non-contact type capacitance induction level sensor

A liquid level sensor and capacitive sensing technology, applied in the field of liquid level sensors, can solve problems such as short service life, failure of water level detection, and easy to be damaged by lightning strikes, so as to reduce the probability of failure and prolong the service life

Inactive Publication Date: 2009-05-13

俞险峰

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AI-Extracted Technical Summary

Problems solved by technology

[0002] The traditional capacitive water level sensor has electrodes exposed in the water, and water acts as a medium to change the capacitance between the electrodes, thereby detecting changes in the water level; the traditional water resistance water level sensor has multiple electrodes, but when the water passes through the electrodes, the gap between the electrodes A weak current flows to detect changes in the water level; if the above two sensors are used in water with high temperature and poor water quality, it is easier to scale and cover the electrodes, resulting in detection failure

For example, the water level sensor in a solar water heater often has a short service life due to the above reasons, and in the thunderstorm season i...

Abstract

A non-contact capacitance induction liquid level sensor comprises an insulation shell, a capacitance induction metal part and a liquid level detection circuit. The insulation shell is vertically arranged, the capacitance induction metal part is vertically arranged inside the shell, and the liquid level detection circuit is arranged inside the shell; the liquid level detection circuit comprises an analog input port which is used for being connected with the capacitance induction metal part, and a liquid level measurement module which is used for detecting a capacitance value of the analog input port, and obtaining a current liquid level value according to a corresponding relation between a preset capacitance value and the liquid level; and the capacitance induction metal part is connected with the analog input port. The invention provides the non-contact capacitance induction liquid level sensor which can be effectively used for a long time even under a harsh environment.

Application Domain

Level indicators by physical variable measurement

Technology Topic

CapacitanceEngineering +3

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Examples

Experimental program(4)

Example Embodiment

[0017] Example 1:

[0018] Refer to figure 1 , A non-contact capacitive sensing liquid level sensor, comprising an insulating housing 1, a capacitive sensing metal piece 2, a liquid level detection circuit 3, and an external signal interface 4. The insulating housing is arranged vertically, and the capacitive sensing metal piece is vertically arranged. Is arranged in a housing, the liquid level detection circuit is installed in the housing, and the liquid level detection circuit includes: an analog input port for connecting with the capacitive sensing metal part; for detecting the capacitance value of the analog input port, and The liquid level measurement module for obtaining the current liquid level value according to the preset correspondence relationship between the capacitance value and the liquid level, and the capacitance sensing metal piece is connected to the analog input port.

[0019] The capacitive sensing metal part is copper clad 2, and no less than two copper clads 2 are sequentially arranged in the housing from top to bottom or from bottom to top. The liquid level measurement module is connected to an external signal interface 4, and the external signal interface 4 is connected to a liquid level display device. A temperature sensor 5 is arranged in the insulating housing, and the temperature detection circuit detects the value of the temperature sensor and transmits a temperature signal through an external interface.

[0020] There is an inherent parasitic capacitance Cp between a single copper pour and the common ground (or between two adjacent copper pours 2). When the liquid is submerged or an object approaches, new capacitances are generated. These capacitances are equivalent to being connected in parallel to the original Above Cp, the program in the liquid level detection circuit chip detects the capacitance change of the copper (or capacitive sensing metal sheet) connected to the corresponding port, and can determine the existence and change of the liquid level by measuring the capacitance change; The copper clad 2 is arranged vertically in the housing 1 from top to bottom, respectively, indicating five liquid level states: full, high, medium, low, and water shortage, that is, the correspondence between the capacitance value and the liquid level is a gear relationship .

[0021] When in use, extend the insulating case into the liquid to be tested, the liquid submerges the insulating case and forms a new capacitance with the copper coating in the insulating case. If two copper coatings are submerged, the capacitance increases by two units; such as four submerges. For copper coating, the capacitance increases by four units. The capacitance change signal is transmitted to the analog input port of the liquid level detection circuit. The program in the liquid level detection circuit chip determines the current liquid level value according to the capacitance change corresponding to the copper coating. , Which is the state of the liquid level; and transmits the liquid level signal through the external signal interface.

[0022] This embodiment can be applied to the water level detection of solar water heaters, and each detection point can be detected from top to bottom: full, high, medium, low, and water shortage states.

Example Embodiment

[0023] Example 2:

[0024] Refer to figure 2 The capacitive sensing metal part of this embodiment is a metal detection strip 22.

[0025] Liquid submerges the insulating shell, and the difference in the area covered by the metal detection strip will cause the change of capacitance. The change value of the capacitance is detected by the liquid level detection circuit 3 to linearly reflect the height and range ratio of the liquid level, that is, the capacitance value and the liquid level. The corresponding relationship is linear.

[0026] The use process of this embodiment is the same as that of the first embodiment.

[0027] This embodiment is applied in an oil tank, and the oil level signal is linearly and continuously transmitted to the automobile control system through an external interface.

[0028] This embodiment can also be applied to a water tank in which the liquid level signal is linearly and continuously transmitted to an external display system through an external signal interface.

Example Embodiment

[0029] Embodiment three:

[0030] The capacitive sensing metal part of this embodiment is a sensing spring.

[0031] The liquid floods the insulating shell, causing the capacitance of the induction spring in the insulating shell to change. The liquid level detection circuit 3 detects the capacitance change value to reflect the liquid level status or range ratio of the detected point.

[0032] The use of the spring keeps the capacitive sensing metal parts in close contact with the inner wall of the insulating shell, improving the sensitivity of liquid level detection, and is especially suitable for insulating shells with larger diameters.

[0033] The use process of this embodiment is the same as that of the first embodiment.

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Description & Claims & Application Information

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Intelligent type heat pump water heater

InactiveCN1632409AExtended service lifeeasy to operate

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Classification and recommendation of technical efficacy words

Reduce the probability of failure
Extended service life

Non-contact type capacitance induction level sensor

A liquid level sensor and capacitive sensing technology, applied in the field of liquid level sensors, can solve problems such as short service life, failure of water level detection, and easy to be damaged by lightning strikes, so as to reduce the probability of failure and prolong the service life

AI-Extracted Technical Summary

Problems solved by technology

Abstract

Image

Examples

Example Embodiment

Example Embodiment

Example Embodiment

PUM

Description & Claims & Application Information

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