CN218297299U - Liquid level detection circuit - Google Patents
Liquid level detection circuit Download PDFInfo
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- CN218297299U CN218297299U CN202220851571.6U CN202220851571U CN218297299U CN 218297299 U CN218297299 U CN 218297299U CN 202220851571 U CN202220851571 U CN 202220851571U CN 218297299 U CN218297299 U CN 218297299U
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Abstract
The utility model discloses a liquid level detection circuit, which comprises an electric signal output unit, a voltage conversion unit, a reference voltage unit and a liquid level sensor; the electric signal output unit is used for outputting an initial electric signal; the voltage conversion unit comprises a voltage detection end, an electrode connection end and an electric signal input end, the electric signal input end is connected with the electric signal output unit, and the voltage detection end is used for outputting detection voltage; the reference voltage unit is provided with a reference voltage end, the liquid level sensor comprises a first electrode and a second electrode, the first electrode is connected with the reference voltage end, and the second electrode is connected with the electrode connecting end; periodically forming a first current and a second current with opposite flow directions between the first electrode and the second electrode as the initial electrical signal periodically changes; the accumulation of charges on the electrodes is avoided, the rusting problem of the electrodes is reduced, and the service lives of the liquid level sensor and the liquid level detection circuit are prolonged.
Description
Technical Field
The utility model relates to a liquid level detection field, especially a liquid level detection circuit.
Background
Electrode level sensors are often used for level detection; for an electrode-type level sensor, it has two electrodes; because water is a conductor and air is an insulator, when only water is communicated between the two electrodes, the two electrodes conduct electricity; when air exists between the two electrodes, the two electrodes are not conductive, and therefore liquid level detection is achieved. However, the electrode can accumulate charges in the long-term use process, which easily causes the electrode to rust, and shortens the service life of the electrode type liquid level sensor.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to solve one of the technical problem that exists among the prior art at least, provide a liquid level detection circuit.
The utility model provides a technical scheme that its problem adopted is:
a liquid level detection circuit comprising:
the electric signal output unit is used for outputting an initial electric signal with periodically changed voltage value;
the voltage conversion unit comprises a voltage detection end, an electrode connection end and an electric signal input end, the electric signal input end is connected with the electric signal output unit, and the voltage detection end is used for outputting detection voltage converted from an initial electric signal;
a reference voltage unit provided with a reference voltage terminal maintaining a constant voltage value;
the liquid level sensor comprises a first electrode and a second electrode, the first electrode is connected with the reference voltage end, and the second electrode is connected with the electrode connecting end;
wherein, as the initial electric signal changes periodically, a first current and a second current are formed between the first electrode and the second electrode periodically, and the flowing directions of the first current and the second current are opposite.
Further, the initial electrical signal is a square wave signal having a constant frequency.
Further, the square wave signal has a maximum voltage value and a minimum voltage value; when the square wave signal is at a maximum voltage value, forming the first current between the first electrode and the second electrode; when the square wave signal is at a minimum voltage value, the second current is formed between the first electrode and the second electrode.
Further, the reference voltage unit comprises a first resistor and a voltage stabilizing diode, and the reference voltage end is led out between the first resistor and the voltage stabilizing diode.
Further, the voltage conversion unit comprises a second resistor and a third resistor, one end of the second resistor is the electrical signal input end, and the other end of the second resistor is connected with the second electrode; one end of the third resistor is the voltage detection end, and the other end of the third resistor is connected with the other end of the second resistor.
Further, the voltage conversion unit is connected with the filtering unit.
Further, the filtering unit includes a capacitor; one end of the capacitor is connected with the other end of the second resistor, and the other end of the capacitor is grounded.
Further, there are a plurality of the voltage conversion units, and a plurality of the second electrodes; and the electrode connecting end of each voltage conversion unit is connected with one second electrode.
Further, the resistance value of the second resistor is 5.1k Ω, and the resistance value of the third resistor is 1k Ω.
Further, the constant voltage value is 2.5V; the voltage value of the initial electric signal ranges from 0V to 5V.
The liquid level detection circuit at least has the following beneficial effects: and along with the periodic change of the initial electric signal, a first current and a second current are periodically formed between the first electrode and the second electrode, wherein the flow directions of the first current and the second current are opposite, and electric charges can flow between the first electrode and the second electrode, so that the accumulation of the electric charges on the electrodes is avoided, the rusting problem of the electrodes is relieved, and the service lives of the liquid level sensor and the liquid level detection circuit are prolonged.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The invention is further described with reference to the following figures and examples.
Fig. 1 is a circuit diagram of a liquid level detection circuit according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a liquid level detection circuit having three second electrodes;
FIG. 3 is a waveform diagram corresponding to the voltage detecting terminal under the condition that the liquid level does not reach the position of the second electrode;
FIG. 4 is a waveform diagram corresponding to the voltage detection terminal in a state where the liquid level reaches the position of the second electrode.
Detailed Description
This section will describe in detail the embodiments of the present invention, preferred embodiments of the present invention are shown in the attached drawings, which are used to supplement the description of the text part of the specification with figures, so that one can intuitively and vividly understand each technical feature and the whole technical solution of the present invention, but they cannot be understood as the limitation of the protection scope of the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship indicated with respect to the orientation description, such as up, down, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, a plurality of meanings are one or more, a plurality of meanings are two or more, and the terms greater than, smaller than, exceeding, etc. are understood as excluding the number, and the terms greater than, lower than, within, etc. are understood as including the number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless there is an explicit limitation, the terms such as setting, installing, connecting, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meaning of the terms in the present invention by combining the specific contents of the technical solution.
The embodiment of the utility model provides a liquid level detection circuit.
Referring to fig. 1, the liquid level detection circuit includes an electric signal output unit 100, a voltage conversion unit 200, a reference voltage unit 300, and a liquid level sensor.
The electrical signal output unit 100 is configured to output an initial electrical signal with a periodically changing voltage value; the voltage converting unit 200 includes a voltage detecting terminal 223, an electrode connecting terminal 221, and an electrical signal input terminal 222, the electrical signal input terminal 222 is connected to the electrical signal output unit 100, and the voltage detecting terminal 223 is used for outputting a detection voltage converted from an initial electrical signal; the reference voltage unit 300 is provided with a reference voltage terminal 330 maintaining a constant voltage value; the liquid level sensor comprises a first electrode 510 and a second electrode 520, wherein the first electrode 510 is connected with the reference voltage end 330, and the second electrode 520 is connected with the electrode connecting end 221; as the initial electrical signal varies periodically, a first current and a second current are periodically formed between the first electrode 510 and the second electrode 520, the first current and the second current flowing in opposite directions.
In this embodiment, when the liquid level reaches the second electrode 520, the first electrode 510 and the second electrode 520 are equivalent to a smaller resistance due to the small resistivity of the liquid; when the liquid level does not reach the second electrode 520, a large resistance is connected between the first electrode 510 and the second electrode 520 due to the large resistivity of the air; then, in the case where the liquid level reaches the second electrode 520 and the case where the liquid level reaches the second electrode 520, the detection voltage of the voltage detection terminal 223 has different values, and by detecting the voltage value of the voltage detection terminal 223, it can be determined whether the liquid level reaches the position of the second electrode 520.
For the liquid level detection circuit, a first current and a second current which are opposite in flow direction are periodically formed between the first electrode 510 and the second electrode 520 along with the periodic change of the initial electric signal, and electric charges can flow between the first electrode 510 and the second electrode 520, so that the accumulation of the electric charges on the electrodes is avoided, the rusting problem of the electrodes is relieved, and the service lives of the liquid level sensor and the liquid level detection circuit are prolonged.
In some embodiments of the present invention, the initial electrical signal is a square wave signal having a constant frequency. Specifically, the constant frequency is 2 hz; of course in other embodiments the constant frequency may be other values, such as 5 hz.
In some embodiments of the present invention, the square wave signal has a maximum voltage value and a minimum voltage value; the voltage value of the initial electrical signal ranges from 0V to 5V, i.e., the maximum voltage value is 5V and the minimum voltage value is 0V. Of course, in other embodiments, the voltage value of the initial electrical signal may take other values according to actual production requirements. When the square wave signal is at a maximum voltage value, a first current is formed between the first electrode 510 and the second electrode 520; when the square wave signal is at a minimum voltage value, a second current is formed between the first electrode 510 and the second electrode 520.
It should be noted that the electrical signal output unit 100 may be a single chip, and the single chip generates a square wave signal with a frequency of 2 hz and a voltage value ranging from 0V to 5V.
In some embodiments of the present invention, the reference voltage unit 300 includes a first resistor 310 and a zener diode 320, and a reference voltage terminal 330 is led between the first resistor 310 and the zener diode 320.
Specifically, one end of the first resistor 310 is connected to a VCC power supply voltage of 5V, the other end of the first resistor 310 is connected to the cathode of the zener diode 320, the anode of the zener diode 320 is grounded, and a wire is led out between the first resistor 310 and the zener diode 320 to serve as a reference voltage terminal 330. The constant voltage value of the reference voltage terminal 330 is specifically 2.5V. Of course, in other embodiments, the constant voltage value may take other values according to actual production requirements.
Of course, the reference voltage unit 300 may further include two capacitors and another zener diode, so that the output voltage of the reference voltage terminal 330 is more stable.
In some embodiments of the present invention, the voltage converting unit 200 includes a second resistor 211 and a third resistor 212; specifically, the second resistor 211 has a resistance of 5.1k Ω, and the third resistor 212 has a resistance of 1k Ω. Of course, in other embodiments, the resistances of the second resistor 211 and the third resistor 212 may be other resistances according to actual production requirements.
One end of the second resistor 211 is an electrical signal input end 222, that is, one end of the second resistor 211 is connected to a square wave signal with a frequency of 2 hz and a voltage value ranging from 0V to 5V. The other end of the second resistor 211 is connected to the second electrode 520; one end of the third resistor 212 is a voltage detection terminal 223, and the other end of the third resistor 212 is connected to the other end of the second resistor 211.
In some embodiments of the present invention, the voltage conversion unit 200 is connected to the filtering unit 400. The filtering unit 400 is used for filtering high frequency noise.
Specifically, the filtering unit 400 includes a capacitor 410 with a small capacitance value; one end of the capacitor 410 is connected to the other end of the second resistor 211, and the other end of the capacitor 410 is grounded.
Referring to fig. 2, in some embodiments of the present invention, there are three voltage converting units 200 and three second electrodes 520; a second electrode 520 is connected to the electrode connection 221 of each voltage conversion unit 200. In addition, three second electrodes 520 are placed at different heights of the wall of the tank to enable detection of liquid levels at different heights.
In this embodiment, referring to fig. 4, in a state where the liquid level reaches the position of the second electrode 520, when the voltage value of the initial electric signal is 5V, the voltage value of the voltage detection terminal 223 is 4V, and when the voltage value of the initial electric signal is 0V, the voltage value of the voltage detection terminal 223 is 1V.
Referring to fig. 3, in a state where the liquid level does not reach the position of the second electrode 520, the voltage value of the voltage detection terminal 223 is 5V when the voltage value of the initial electrical signal is 5V, and the voltage value of the voltage detection terminal 223 is 0V when the voltage value of the initial electrical signal is 0V.
The above description is only a preferred embodiment of the present invention, and the present invention is not limited to the above embodiment, and the technical effects of the present invention can be achieved by the same means, which all belong to the protection scope of the present invention.
Claims (10)
1. A liquid level detection circuit, characterized in that the liquid level detection circuit comprises:
the electric signal output unit is used for outputting an initial electric signal with periodically changed voltage value;
the voltage conversion unit comprises a voltage detection end, an electrode connecting end and an electric signal input end, the electric signal input end is connected with the electric signal output unit, and the voltage detection end is used for outputting detection voltage converted from an initial electric signal;
a reference voltage unit provided with a reference voltage terminal maintaining a constant voltage value;
the liquid level sensor comprises a first electrode and a second electrode, the first electrode is connected with the reference voltage end, and the second electrode is connected with the electrode connecting end;
wherein, as the initial electric signal periodically changes, a first current and a second current are periodically formed between the first electrode and the second electrode, and the flowing directions of the first current and the second current are opposite.
2. The liquid level detecting circuit according to claim 1, wherein the initial electrical signal is a square wave signal having a constant frequency.
3. The liquid level detecting circuit according to claim 2, wherein the square wave signal has a maximum voltage value and a minimum voltage value; when the square wave signal is at a maximum voltage value, forming the first current between the first electrode and the second electrode; when the square wave signal is at a minimum voltage value, the second current is formed between the first electrode and the second electrode.
4. The liquid level detection circuit according to claim 1, wherein the reference voltage unit includes a first resistor and a zener diode, and the reference voltage terminal is led between the first resistor and the zener diode.
5. The liquid level detection circuit according to claim 1, wherein the voltage conversion unit includes a second resistor and a third resistor, one end of the second resistor is the electrical signal input end, and the other end of the second resistor is connected to the second electrode; one end of the third resistor is the voltage detection end, and the other end of the third resistor is connected with the other end of the second resistor.
6. The liquid level detection circuit according to claim 5, wherein the voltage conversion unit is connected to a filter unit.
7. The liquid level detecting circuit according to claim 6, wherein the filter unit includes a capacitor; one end of the capacitor is connected with the other end of the second resistor, and the other end of the capacitor is grounded.
8. The liquid level detecting circuit according to claim 1, wherein the voltage converting unit is provided in plurality, and the second electrode is provided in plurality; and the electrode connecting end of each voltage conversion unit is connected with one second electrode.
9. The liquid level detecting circuit according to claim 5, wherein the second resistor has a resistance of 5.1k Ω, and the third resistor has a resistance of 1k Ω.
10. The liquid level detecting circuit according to claim 1, wherein the constant voltage value is 2.5V; the voltage value of the initial electric signal ranges from 0V to 5V.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220851571.6U CN218297299U (en) | 2022-04-13 | 2022-04-13 | Liquid level detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202220851571.6U CN218297299U (en) | 2022-04-13 | 2022-04-13 | Liquid level detection circuit |
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| CN218297299U true CN218297299U (en) | 2023-01-13 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114916830A (en) * | 2022-04-13 | 2022-08-19 | 广东智科电子股份有限公司 | Control circuit and control method for water heater |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114916830A (en) * | 2022-04-13 | 2022-08-19 | 广东智科电子股份有限公司 | Control circuit and control method for water heater |
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