CN220729395U - Circuit for detecting liquid level of automobile - Google Patents
Circuit for detecting liquid level of automobile Download PDFInfo
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- CN220729395U CN220729395U CN202322522408.2U CN202322522408U CN220729395U CN 220729395 U CN220729395 U CN 220729395U CN 202322522408 U CN202322522408 U CN 202322522408U CN 220729395 U CN220729395 U CN 220729395U
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- liquid level
- electrically connected
- level sensor
- resistor
- detection
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- 239000007788 liquid Substances 0.000 title claims abstract description 111
- 238000001514 detection method Methods 0.000 claims abstract description 58
- 239000003990 capacitor Substances 0.000 claims abstract description 43
- 239000012530 fluid Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 3
- 239000000523 sample Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
Abstract
The application relates to a circuit for detecting liquid level of an automobile, and relates to the technical field of liquid level detection; the liquid level sensor comprises a controller, a liquid level sensor and a comparison unit; the output end of the controller is electrically connected to the input end of the liquid level sensor and is used for outputting PWM voltage; the liquid level sensor comprises a detection capacitor Cx, is used for detecting the current liquid level and outputting detection voltage, and the output end of the liquid level sensor is electrically connected to the input end of the comparison unit; the comparison unit is used for comparing the detection voltage with a preset reference voltage, and the output end of the comparison unit is electrically connected to the input end of the controller. The liquid level detection device has the effect of detecting the liquid level in the container more accurately.
Description
Technical Field
The application relates to the technical field of liquid level detection, in particular to a circuit for detecting the liquid level of an automobile.
Background
At present, most automobiles such as an antifreezing solution storage tank are provided with a liquid level detection device in a container for storing liquid, and when the liquid in the container has the phenomena of light consumption or low liquid level, the liquid level detection device can send an alarm signal to remind the user of replenishing the liquid in time. In the prior art, a float switch is utilized in an automobile liquid level detection device, and a switch signal is directly detected for an MCU by the height of a float reaching a specified liquid level, so that the liquid levels of liquid in a plurality of oil tanks can be detected.
However, in actual use, the floating ball is easy to damage, so that false alarm occurs in the automobile controller system.
Disclosure of Invention
In order to more accurately detect the liquid level in the container, the application provides a circuit for detecting the liquid level of an automobile.
The application provides a circuit for automobile liquid level detection adopts following technical scheme:
a circuit for detecting the liquid level of an automobile comprises a controller, a liquid level sensor and a comparison unit; the output end of the controller is electrically connected to the input end of the liquid level sensor and is used for outputting PWM voltage; the liquid level sensor is arranged as a capacitive liquid level sensor and comprises a detection capacitor Cx and is used for detecting the current liquid level and outputting detection voltage, and the output end of the liquid level sensor is electrically connected to the input end of the comparison unit; the comparison unit is used for comparing the detection voltage with a preset reference voltage, and the output end of the comparison unit is electrically connected to the input end of the controller.
By adopting the technical scheme, the capacitive liquid level detection is utilized to replace the floating ball switch, so that the durability of the liquid level sensor is improved, the liquid level in the container can be detected more accurately, and the liquid level can be converted into detection voltage to be output to the comparison unit; the comparison unit is used for comparing the detection voltage with the reference voltage, so that whether the current container is in a liquid shortage state or a liquid empty state can be judged through the controller.
Preferably, a buffer unit is connected in series between the output end of the controller and the input end of the liquid level sensor.
By adopting the technical scheme, the buffer unit is utilized to avoid the influence of the controller on the voltage of the detection capacitor Cx.
Preferably, the buffer unit includes a buffer chip U1 and a first power source V1, the dynamic control terminal of the buffer chip UI is electrically connected to the voltage output terminal of the first power source V1 through a resistor R7, the input terminal of the buffer chip UI is electrically connected to the output terminal of the controller, and the output terminal of the buffer chip UI is electrically connected to the input terminal of the liquid level sensor.
By adopting the technical scheme, the buffer chip U1 can always buffer the unit in the power supply state.
Preferably, the comparing unit comprises a comparator U2, a reference voltage module and a first power supply V1, wherein the voltage output end of the first power supply V1 is electrically connected to the power supply end of the comparator U2, and the grounding end of the comparator U2 is grounded; the output end of the liquid level sensor is electrically connected to the first input end of the comparator U2 and is used for outputting detection voltage; the output end of the reference voltage module is electrically connected to the second output end of the comparator U2, and the reference voltage module is used for providing reference voltage; the output of the comparator U2 is electrically connected to the input of the controller.
By adopting the technical scheme, the comparison of the reference voltage and the detection voltage is realized by using the comparator U2, and when the detection voltage is smaller than the reference voltage, the output end of the comparator U2 continuously outputs high level; when the detection voltage is greater than the reference voltage, the liquid level reaches a low liquid level or a liquid-air state, and the output end of the comparator U2 outputs a low level.
Preferably, the reference voltage module includes a resistor R4 and a resistor R5, the voltage output terminal of the first power supply V1 is grounded through the resistor R4 and the resistor R5 in sequence, and the connection between the resistor R4 and the resistor R5 is electrically connected to the second output terminal of the comparator U2.
By adopting the technical scheme, the reference voltage is provided, so that the lowest position of the liquid in the container is set.
Preferably, the comparing unit further includes a pull-up resistor R6 and a capacitor C5, the voltage output terminal of the first power supply V1 is electrically connected to the positive electrode of the capacitor C5 through the pull-up resistor R6, the capacitor C5 is grounded, and the positive electrode of the capacitor C5 is electrically connected to the output terminal of the comparator U2.
By adopting the technical scheme, the stability of the output voltage of the comparison unit is improved.
Preferably, the liquid level sensor further comprises a TVS diode D1, wherein the input end of the liquid level sensor is electrically connected to one end of the TVS diode D1, and the other end of the TVS diode D1 is grounded.
By adopting the technical scheme, the TVS diode D1 is utilized to play a role in preventing surge, and the circuit is protected.
Preferably, the liquid level sensor further comprises a TVS diode D2, wherein the output end of the liquid level sensor is electrically connected to one end of the TVS diode D2, and the other end of the TVS diode D2 is grounded.
By adopting the technical scheme, the TVS diode D2 is utilized to play a role in preventing surge, and the circuit is protected.
In summary, the present application includes at least one of the following beneficial technical effects: the voltage output by the singlechip is output to the liquid level sensor through the buffer list, so that the detection capacitance Cx can be charged and discharged; then, the comparison unit is used for comparing the detection voltage with the reference voltage, and when the liquid level reaches a low liquid level or a liquid-air state, the detection voltage is larger than the reference voltage, the comparator U2 outputs the level, so that the detection of the liquid level is realized; and utilize capacitive liquid level sensor can also improve the durability when realizing liquid level detection to make liquid level detection's result more accurate.
Drawings
FIG. 1 is a functional block diagram of an embodiment of the present application;
FIG. 2 is a circuit diagram mainly used for showing a buffer unit in the embodiment of the present application;
fig. 3 is a circuit diagram of a comparison unit in an embodiment of the present application.
Reference numerals: 1. a liquid level sensor; 2. a buffer unit; 3. a comparison unit; 31. and a reference voltage module.
Detailed Description
The present application is described in further detail below in conjunction with figures 1-3.
The embodiment of the application discloses a circuit for detecting the liquid level of an automobile.
Referring to fig. 1, a circuit for detecting the liquid level of an automobile comprises a controller, a liquid level sensor 1, a buffer unit 2 and a comparison unit 3, wherein the liquid level sensor 1 is used for collecting data of the liquid level in a container and converting the data into an electric signal. The PWM_IN output end of the controller is electrically connected to the input end of the liquid level sensor 1 through the buffer unit 2, the output end of the liquid level sensor 1 is electrically connected to the comparison unit 3, and the output end of the comparison unit 3 is electrically connected to the input end of the controller. The comparing unit 3 is used for comparing the voltage output by the liquid level sensor 1 with a reference voltage set by the comparing unit, so as to output a comparison result into the controller, and further judge whether the current liquid level is lower than a minimum limit value.
In this embodiment, the liquid level sensor 1 is configured as a capacitive liquid level sensor, and includes a detection capacitor Cx, a resistor Rx and a resistor Ro, where the capacitive liquid level sensor implements liquid level detection by a capacitance change between two probes, that is, when the liquid level changes, the capacitance value of the detection capacitor Cx changes, so that the output voltage of the liquid level sensor 1 changes. The positive electrode of the detection capacitor Cx is electrically connected to the output terminal of the buffer unit 2, the negative electrode of the detection capacitor Cx is electrically connected to one end of the resistor Rx, the other end of the resistor Rx is electrically connected to one end of the resistor Ro, the other end of the resistor Ro is electrically connected to the positive electrode of the detection capacitor Cx, and the junction between the resistor Rx and the resistor Ro is the output terminal of the liquid level sensor 1. Since the position of the probe of the capacitive liquid level sensor is generally fixed and not easily damaged, the accuracy of detection by the capacitive liquid level sensor is higher.
Referring to fig. 2, the buffer unit 2 includes a buffer chip UI, a capacitor C6 and a resistor R7, and a first power supply V1, and the power supply voltage of the first power supply V1 in the embodiment of the present application is set to 5V. The ground pin GND of the buffer chip UI is grounded, the power supply pin VCC of the buffer chip UI is electrically connected to the voltage output terminal of the first power supply V1, and one end of the voltage output terminal of the first power supply V1 is electrically connected to the positive electrode of the capacitor C6, and the negative electrode of the capacitor C6. The capacitor C6 is used for filtering, so that the buffer chip UI can operate more stably. The voltage output terminal of the first power supply V1 is electrically connected to the input pin OE of the buffer chip UI through the resistor R7, so that the buffer chip U1 can always play a role in buffering when it is powered. The output terminal pwm_in of the controller is electrically connected to the input pin a of the buffer chip UI for outputting PWM waveform voltage, and the output pin Y of the buffer chip UI is the output terminal of the buffer unit 2. The PWM waveform voltage is output to the input end of the liquid level sensor 1 through the buffer unit 2, the PWM waveform voltage is used for charging and discharging the detection capacitor Cx, and the buffer unit 2 is used for avoiding the influence of the controller on the voltage of the detection capacitor Cx.
Referring to fig. 2, the present embodiment further includes a capacitor C1, a capacitor C2, a capacitor C3, a TVS diode D1, a TVS diode D2, a resistor R1, a resistor R2, and a resistor R3. The output terminal of the buffer unit 2 is electrically connected to the positive electrode of the capacitor C1 through the resistor R1, and the negative electrode of the capacitor C1 is electrically connected to the input terminal of the liquid level sensor 1. One end of the TVS diode D1 is electrically connected to the negative electrode of the capacitor C1, and the other end of the TVS diode D1 is grounded. The output end of the liquid level sensor 1 is electrically connected to the positive electrode of the capacitor C2, and the negative electrode of the capacitor C2 is grounded. One end of the TVS diode D2 is electrically connected to the positive electrode of the capacitor C2, and the other end of the TVS diode D2 is grounded. The positive electrode of the capacitor C1 is electrically connected to one end of the resistor R2, the other end of the resistor R2 is electrically connected to the positive electrode of the capacitor C3, the negative electrode of the capacitor C3 is grounded, and the positive electrode of the capacitor C3 is electrically connected to one end of the resistor R3, and the other end of the resistor R3 is for outputting the detection voltage Ut. The TVS diode D1 and the TVS diode D2 both play a role in preventing surge so as to achieve the purpose of protecting a circuit.
Referring to fig. 3, the comparison unit 3 includes a comparator U2, a capacitor C4, and a reference voltage module 31. The voltage output end of the first power supply V1 is electrically connected to the power supply end of the comparator U2, the ground of the comparator U2 is grounded, and the detection voltage Ut is output to the inverting input end of the comparator U2. The positive electrode of the capacitor C4 is electrically connected to the voltage output end of the first power supply V1, and the negative electrode of the capacitor C4 is grounded for improving the stability of the voltage output of the first power supply V1. The reference voltage module 31 includes a resistor R4 and a resistor R5, the voltage output terminal of the first power supply V1 is electrically connected to one end of the resistor R4, the other end of the resistor R4 is electrically connected to one end of the resistor R5, the other end of the resistor R5 is grounded, and a junction between the resistor R4 and the resistor R5 is electrically connected to the non-inverting input terminal of the comparator U2 for outputting the reference voltage Ub.
When the liquid is immersed into the probe of the liquid level sensor 1, the capacitance value of the detection capacitor Cx is increased, the detection voltage Ut is smaller than the reference voltage Ub at the moment, and the output end of the comparator U2 continuously outputs a high level; when the liquid level reaches a low liquid level or a liquid-air state, the capacitance value of the detection capacitor Cx is reduced, the detection voltage Ut is larger than the reference voltage Ub, the output end of the comparator U2 outputs a low level, and an alarm signal can be sent by the controller to remind that the liquid needs to be replenished.
In addition to this, the comparison unit 3 comprises a capacitor C4 and a pull-up resistor R6. The voltage output terminal of the first power supply V1 is electrically connected to one end of the pull-up resistor R6, the other end of the pull-up resistor R6 is electrically connected to the positive electrode of the capacitor C5, and the negative electrode of the capacitor C5 is grounded, thereby improving the stability of the output voltage of the comparing unit 3.
The implementation principle of the circuit for detecting the liquid level of the automobile is as follows: after passing through the buffer unit 2, the PWM voltage output by the singlechip is utilized to charge and discharge the detection capacitance Cx in the liquid level sensor 1, the comparison unit 3 is utilized to compare the detection voltage Ut with the reference voltage Ub, when the liquid level reaches a low liquid level or a liquid-air state, the detection voltage Ut is increased, and the comparator U2 outputs a low pulse. The capacitive liquid level sensor 1 can realize liquid level detection and improve durability, so that the liquid level detection result is more accurate.
The foregoing are all preferred embodiments of the present application, and are not intended to limit the scope of the present application in any way, therefore: all equivalent changes in structure, shape and principle of this application should be covered in the protection scope of this application.
Claims (8)
1. A circuit for detecting the liquid level of an automobile, characterized in that: comprises a controller, a liquid level sensor (1) and a comparison unit (3); the output end of the controller is electrically connected to the input end of the liquid level sensor (1) and is used for outputting PWM voltage; the liquid level sensor (1) is arranged as a capacitive liquid level sensor and comprises a detection capacitance Cx used for detecting the current liquid level and outputting detection voltage, and the output end of the liquid level sensor (1) is electrically connected to the input end of the comparison unit (3); the comparison unit (3) is used for comparing the detection voltage with a self-preset reference voltage, and the output end of the comparison unit (3) is electrically connected to the input end of the controller.
2. A circuit for automotive liquid level detection as claimed in claim 1, wherein: a buffer unit (2) is connected in series between the output end of the controller and the input end of the liquid level sensor (1).
3. A circuit for automotive fluid level detection as defined in claim 2, wherein: the buffer unit (2) comprises a buffer chip U1 and a first power supply V1, wherein a dynamic control end of the buffer chip UI is electrically connected to a voltage output end of the first power supply V1 through a resistor R7, an input end of the buffer chip UI is electrically connected to an output end of the controller, and an output end of the buffer chip UI is electrically connected to an input end of the liquid level sensor (1).
4. A circuit for automotive liquid level detection as claimed in claim 1, wherein: the comparison unit (3) comprises a comparator U2, a reference voltage module (31) and a first power supply V1, wherein the voltage output end of the first power supply V1 is electrically connected to the power supply end of the comparator U2, and the grounding end of the comparator U2 is grounded; the output end of the liquid level sensor (1) is electrically connected to the first input end of the comparator U2 and is used for outputting detection voltage; an output end of the reference voltage module (31) is electrically connected to a second output end of the comparator U2, and the reference voltage module (31) is used for providing a reference voltage; the output of the comparator U2 is electrically connected to the input of the controller.
5. A circuit for automotive liquid level detection as claimed in claim 4, wherein: the reference voltage module (31) comprises a resistor R4 and a resistor R5, the voltage output end of the first power supply V1 is grounded through the resistor R4 and the resistor R5 in sequence, and the connection part between the resistor R4 and the resistor R5 is electrically connected to the second output end of the comparator U2.
6. A circuit for automotive liquid level detection as claimed in claim 4, wherein: the comparing unit (3) further comprises a pull-up resistor R6 and a capacitor C5, the voltage output terminal of the first power supply V1 is electrically connected to the positive electrode of the capacitor C5 through the pull-up resistor R6, the capacitor C5 is grounded, and the positive electrode of the capacitor C5 is electrically connected to the output terminal of the comparator U2.
7. A circuit for automotive liquid level detection as claimed in claim 1, wherein: the liquid level sensor further comprises a TVS diode D1, wherein the input end of the liquid level sensor (1) is electrically connected to one end of the TVS diode D1, and the other end of the TVS diode D1 is grounded.
8. A circuit for automotive liquid level detection as claimed in claim 1, wherein: the liquid level sensor further comprises a TVS diode D2, wherein the output end of the liquid level sensor (1) is electrically connected to one end of the TVS diode D2, and the other end of the TVS diode D2 is grounded.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322522408.2U CN220729395U (en) | 2023-09-15 | 2023-09-15 | Circuit for detecting liquid level of automobile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322522408.2U CN220729395U (en) | 2023-09-15 | 2023-09-15 | Circuit for detecting liquid level of automobile |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220729395U true CN220729395U (en) | 2024-04-05 |
Family
ID=90491401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202322522408.2U Active CN220729395U (en) | 2023-09-15 | 2023-09-15 | Circuit for detecting liquid level of automobile |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN220729395U (en) |
-
2023
- 2023-09-15 CN CN202322522408.2U patent/CN220729395U/en active Active
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