Liquid level switch circuit

Abstract

The utility model discloses a liquid level switch circuit, which comprises a processing chip U1 provided with an output circuit for outputting switch signals; the power supply circuit is electrically connected with a power supply port of the processing chip U1; the capacitance reference circuit is electrically connected with a reference port of the processing chip U1; the detection circuit is electrically connected with the detection port of the processing chip U1, the detection circuit comprises a detection electrode K1, and the detection electrode K1 is arranged opposite to the preset liquid level position of the liquid container; when the actual liquid level in the liquid container reaches a preset liquid level position, the detection capacitance value of the detection circuit is matched with the reference capacitance value of the capacitance value reference circuit; the processing chip U1 is used for comparing the detection capacitance value with the reference capacitance value and enabling the output circuit to output a switching signal when the actual liquid level in the liquid container reaches the preset liquid level position, and the liquid level detection circuit has the advantages of being accurate in detection, high in reliability and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to detection circuit field especially relates to a liquid level switch circuit. BACKGROUND

[0002] Liquid level switch is also called water level switch or liquid level sensor, and the switch is triggered by detecting the height of liquid level to make corresponding action or alarm. Common liquid level switches include float ball type, magnetic flap type, ultrasonic type and the like. Taking the float ball type liquid level switch as an example, it mainly comprises a float ball floating on the liquid surface and a micro switch connected with the float ball through a connecting rod, when the liquid level rises or falls, the height position of the float ball changes, thereby driving the opening and closing of the micro switch through the connecting rod. Although the float ball type liquid level switch has simple structure and is widely used, when the liquid surface fluctuates greatly, the float ball is prone to violent up and down fluctuation or jamming, which causes the liquid level switch to malfunction, and the reliability is general and the precision is low. SUMMARY

[0003] The utility model aims at at least solving one of the technical problems existing in the prior art, and proposes a liquid level switch circuit, which can realize stable and reliable high-precision liquid level detection.

[0004] The utility model discloses a liquid level switch circuit, which comprises a processing chip U1, an output circuit with an output switch signal, a power supply circuit 10 electrically connected with a power supply port of the processing chip U1, a capacitance reference circuit 20 electrically connected with a reference port of the processing chip U1, and a detection circuit 30 electrically connected with a detection port of the processing chip U1. The detection circuit 30 comprises a detection electrode K1, which is arranged opposite to a preset liquid level position of a liquid container. When the actual liquid level in the liquid container reaches the preset liquid level position, the detection capacitance value of the detection circuit 30 matches the reference capacitance value of the capacitance reference circuit 20. The processing chip U1 is used for comparing the detection capacitance value with the reference capacitance value, and the output circuit outputs the switch signal when the actual liquid level in the liquid container reaches the preset liquid level position.

[0005] In some preferred embodiments, the capacitance reference circuit 20 comprises a resistor R6, a charge detection capacitor C3 connected between the resistor R6 and the ground, and a charge modulation capacitor C4 connected in parallel with the charge detection capacitor C3.

[0006] In some preferred embodiments, the detection circuit 30 further comprises a resistor R5 connected in series between the detection port and the detection electrode K1.

[0007] In some preferred embodiments, the output circuit comprises a current limiting resistor R4 connected in series at the control port of the processing chip U1.

[0008] In some preferred embodiments, the power supply circuit 10 comprises an RC filter circuit.

[0009] In some preferred embodiments, the RC filter circuit comprises a filter capacitor C1 and a decoupling capacitor C2 arranged in parallel between a DC power supply Vcc and ground, and a resistor R1 connected in series between the DC power supply Vcc and the power supply port.

[0010] In some preferred embodiments, the liquid level switch circuit further comprises a switch signal indication circuit 40 for emitting a prompt light when the output circuit outputs a switch signal.

[0011] In some preferred embodiments, the switch signal indication circuit 40 comprises an indicator lamp D0 connected in series between the DC power supply Vcc and a control port of the processing chip U1 through a resistor R3.

[0012] In some preferred embodiments, the output circuit outputs a low-level switch signal, and the cathode of the indicator lamp D0 is connected to the control port.

[0013] Compared with the prior art, the liquid level switch circuit has the following beneficial effects:

[0014] The liquid level switch circuit detects the capacitance value when the liquid container is at different liquid level heights by using a non-contact detection electrode, compares the detection capacitance value with the reference capacitance value set by the capacitance reference circuit through the processing chip, and judges that the detection capacitance and the reference capacitance value satisfy the matching relationship when the actual liquid level in the liquid container reaches the preset liquid level position, so as to output a switch signal through the output circuit. Since the detection electrode uses a non-contact detection method to detect the equivalent capacitance value of the liquid container, the detection result is not affected when the liquid surface fluctuates violently, and the detection result is accurate and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic diagram of the liquid level switch circuit disclosed by the utility model.

[0016] Figure 2 is a schematic diagram of the installation of the detection electrode. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects taken by the present application to achieve the predetermined purpose, the specific embodiments, structures, features and effects of the present application will be described in detail below in combination with the drawings and preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0018] AsFigure 1 、 Figure 2 The utility model discloses a liquid level switch circuit, including processing chip U1, power supply circuit 10, capacitance reference circuit 20 and detection circuit 30, power supply circuit 10, capacitance reference circuit 20 and detection circuit 30 are electrically connected respectively in the power supply port, reference port and detection port of processing chip U1, the detection circuit 30 includes detection electrode K1, detection electrode K1 with the preset liquid level position of liquid container is opposite and is set, generally is with the detection electrode K1 set liquid container outside and is located with the equal height of preset liquid level position, capacitance reference circuit 20 is used for setting reference capacitance value in advance, makes reference capacitance value and the actual liquid level in liquid container reach the detection capacitance value of preset liquid level position of detection circuit 30 match, for example, lets reference capacitance value and detection capacitance value between certain proportional relationship, processing chip U1 has the output circuit connected in control port, is used for output switch signal through output circuit, specifically, processing chip U1 is used for comparing the detection capacitance value with the reference capacitance value, when the actual liquid level in the liquid container reaches the preset liquid level position, makes the output circuit output switch signal.

[0019] Detection electrode K1 as a conductive electrode plate, the liquid in the liquid container as another conductive electrode plate of capacitor, two conductive electrode plates are sandwiched between a layer of non-conductive liquid container wall or insulating medium between the outer wall of liquid container and detection electrode K1, together constitute a variable capacitor with different capacitance value that changes with the liquid level in the liquid container.

[0020] The detection port of processing chip U1 obtains the capacitance value of the variable capacitor containing the liquid container in real time through detection electrode K1, and takes the detection capacitance value as the basis for judging the liquid level height in the liquid container.

[0021] The liquid level switch circuit of the utility model detects the capacitance value of different liquid level height in the liquid container through detection electrode K1 in a non-contact mode, compares the detection capacitance value with the reference capacitance value set through capacitance reference circuit 20 by processing chip U1, and when the actual liquid level in the liquid container reaches the preset liquid level position, processing chip U1 judges that the detection capacitance and the reference capacitance value satisfy the matching relationship, so as to output the switch signal through the output circuit.

[0022] Those skilled in the art can understand that the processing chip U1 can be realized by existing single-chip microcomputer, FPGA and other integrated circuit chips, and the processing chip U1 can also be realized by a cheaper capacitance sensing chip, for example, the capacitance sensing chip of model ANY01, SC01B designed and produced by ICman company can be purchased on the market.

[0023] For example, for a real liquid container 9, a preset liquid level position (the preset liquid level position generally corresponds to the lowest liquid level or the highest liquid level of the liquid container) is provided, the detection electrode K1 is directly fixed on the liquid container outside surface at the same height of the preset liquid level position, and the detection capacitance value when the actual liquid level in the liquid container reaches the preset liquid level position is determined by the existing means through the detection electrode K1. The reference capacitance value of the capacitance reference circuit 20 can be determined according to a certain proportional relationship.

[0024] For example, in some embodiments, the capacitance reference circuit 20 includes a resistor R6, a charge detection capacitor C3 connected between the resistor R6 and the ground, and a charge modulation capacitor C4 connected in parallel with the charge detection capacitor C3. By selecting appropriate capacitances of C3 and C4, the equivalent capacitance of the capacitance reference circuit 20 can be determined as the predetermined reference capacitance value.

[0025] The detection circuit 30 further includes a resistor R5 connected in series between the detection port and the detection electrode K1.

[0026] The power supply circuit 10 is used to filter, decouple and process the direct current power supply Vcc and provide it to the processing chip U1, so as to ensure that the processing chip U1 has better anti-interference performance.

[0027] The power supply circuit 10 includes an RC filter circuit. For example, the RC filter circuit includes a filter capacitor C1 and a decoupling capacitor C2 arranged in parallel between the direct current power supply Vcc and the ground, and a resistor R1 connected in series between the direct current power supply Vcc and the power supply port.

[0028] The output circuit includes a current limiting resistor R4 connected in series at the control port of the processing chip U1. In some embodiments, when the processing chip U1 determines that the actual liquid level in the liquid container reaches the preset liquid level position, the control port maintains the normal output of high level through the current limiting resistor R4; and when the actual liquid level in the liquid container reaches the preset liquid level position, the control port of the processing chip U1 switches to output a low level switch signal.

[0029] In some embodiments, the liquid level switch circuit further includes a switch signal indication circuit 40 for emitting a prompt light when the output circuit outputs a switch signal, so as to provide a more intuitive reminder to the user.

[0030] For example, the switch signal indication circuit 40 includes an indicator lamp D0 connected in series between the direct current power supply Vcc and the control port of the processing chip U1 through a resistor R3. The indicator lamp D0 generally adopts a light emitting diode.

[0031] As mentioned above, the output circuit outputs a low level switch signal, the cathode of the indicator D0 is electrically connected to the control port, and the anode is connected to the DC power supply Vcc through the resistor R3.

[0032] Of course, if the normal level of the control port of the processing chip U1 is low, when the actual liquid level in the liquid container reaches the preset liquid level position, the control port of the processing chip U1 switches to output a high level switch signal, at this time, the anode of the indicator D0 is electrically connected to the control port, and the cathode is connected to the DC power supply Vcc through the resistor R3.

[0033] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A liquid level switch circuit, characterized by The application relates to a liquid level detection circuit, which comprises: a processing chip U1 with an output circuit outputting a switch signal; a power supply circuit (10) electrically connected with a power supply port of the processing chip U1; a capacitance reference circuit (20) electrically connected with a reference port of the processing chip U1; a detection circuit (30) electrically connected with a detection port of the processing chip U1, wherein the detection circuit (30) comprises a detection electrode K1, which is arranged opposite to a preset liquid level position of a liquid container, so that when an actual liquid level in the liquid container reaches the preset liquid level position, a detection capacitance value of the detection circuit (30) matches a reference capacitance value of the capacitance reference circuit (20); the processing chip U1 is used for comparing the detection capacitance value with the reference capacitance value, and outputting the switch signal through the output circuit when the actual liquid level in the liquid container reaches the preset liquid level position.

2. The liquid level switch circuit of claim 1, wherein, The capacitance reference circuit (20) comprises a resistor R6, a charge detection capacitor C3 connected between the resistor R6 and the ground, and a charge modulation capacitor C4 connected in parallel with the charge detection capacitor C3.

3. The liquid level switch circuit of claim 1, wherein, The detection circuit (30) further comprises a resistor R5 connected in series between the detection port and the detection electrode K1.

4. The liquid level switch circuit of claim 1, wherein, The output circuit comprises a current-limiting resistor R4 connected in series at a control port of the processing chip U1.

5. The liquid level switch circuit of claim 1, wherein, The power supply circuit (10) comprises an RC filter circuit.

6. The liquid level switch circuit of claim 5, wherein, The RC filter circuit comprises a filter capacitor C1 and a decoupling capacitor C2 arranged in parallel between a direct current power supply Vcc and the ground, and a resistor R1 connected in series between the direct current power supply Vcc and the power supply port.

7. A liquid level switch circuit according to any one of claims 1-6, characterised in that, The application further comprises a switch signal indication circuit (40) for emitting a prompt light when the output circuit outputs the switch signal.

8. The liquid level switch circuit of claim 7, wherein, The switch signal indication circuit (40) comprises an indicating lamp D0 connected in series between the direct current power supply Vcc and the control port of the processing chip U1 through a resistor R3.

9. The liquid level switch circuit of claim 8, wherein, The output circuit outputs the switch signal as a low level, and a cathode of the indicating lamp D0 is connected with the control port.

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