Liquid level detection device, heat management system and vehicle

Abstract

The utility model provides a liquid level detection device, a heat management system and a vehicle, and relates to the technical field of liquid level detection. The liquid level detection device comprises a liquid level sensor, a PWM (Pulse Width Modulation) circuit and a control circuit, and the liquid level sensor is configured to be arranged in a liquid storage device of the thermal management system; the PWM circuit comprises a comparator, the non-inverting input end of the comparator is connected with the liquid level sensor, the liquid level sensor is used for receiving a PWM excitation signal, the inverting input end of the comparator is provided with a reference voltage dividing resistor, the reference voltage dividing resistor is used for adjusting the reference voltage of the comparator, and the output end of the comparator is connected with the control circuit. According to the utility model, the reference voltage can be adjusted and can adapt to the characteristics or working conditions of different liquid level sensors, so that the distinguishing capability of empty and full states is improved, and short-time fluctuation signals in a critical state can be filtered, thereby realizing reliable liquid level detection.

Description

Technical Field

[0001] This utility model relates to the field of liquid level detection technology, and more specifically, to a liquid level detection device, a thermal management system, and a vehicle. Background Technology

[0002] The automotive thermal management system is used to maintain the normal operating temperature of various vehicle components. Through effective thermal control, it ensures the performance and durability of components such as the engine, battery pack, and air conditioning. The system is usually divided into two parts: heating and cooling. The cooling function mainly relies on the phase change process of evaporation and condensation of condensate or refrigerant in a closed circulation system to transfer heat. Normal circulation and the evaporation of refrigerant or coolant will cause changes in liquid level, so liquid level detection is required.

[0003] In related technologies, an RC low-frequency signal injection solution is used for liquid level detection. The controller's main chip sends a low-frequency PWM excitation signal, which is transmitted to the liquid level sensor via capacitive coupling, and then the PWM response signal is transmitted back to the main chip via another capacitive coupling. When the coolant level changes, the amplitude of the response signal changes. The main chip analyzes the time-domain voltage characteristics of the PWM response signal to calculate the coolant level data, thus predicting whether the liquid level is "empty" or "full." However, during the PWM input process, the RC circuit's PWM waveform is easily affected by external noise, which can lead to false alarms. Utility Model Content

[0004] The problem this invention solves is how to achieve reliable liquid level detection.

[0005] To address the aforementioned problems, this utility model provides a liquid level detection device, a thermal management system, and a vehicle.

[0006] In a first aspect, this utility model provides a liquid level detection device, including a liquid level sensor, a PWM circuit, and a control circuit. The liquid level sensor is configured to be installed in a liquid storage device of a thermal management system. The PWM circuit includes a comparator, the non-inverting input terminal of which is connected to the liquid level sensor, the liquid level sensor being used to receive a PWM excitation signal, and the inverting input terminal of the comparator being provided with a reference voltage divider resistor, the reference voltage divider resistor being used to adjust the reference voltage of the comparator. The output terminal of the comparator is connected to the control circuit.

[0007] Optionally, the liquid level sensor includes a sixth resistor, a seventh resistor, and a first capacitor. The seventh resistor and the first capacitor are connected in series to form a first branch, and the sixth resistor is connected in parallel with the first branch. One end of the sixth resistor and one end of the first branch are both connected to the liquid level output terminal of the PWM circuit. The liquid level output terminal is connected to the positive input terminal of the comparator. The other end of the sixth resistor and the other end of the first branch are both connected to the liquid level input terminal of the PWM circuit.

[0008] Optionally, the liquid level output terminal includes a second capacitor, one end of which is connected to one end of the sixth resistor and one end of the first branch, and the other end of which is connected to the non-inverting input terminal of the comparator; the liquid level input terminal includes a third capacitor, one end of which is connected to the other end of the sixth resistor and the other end of the first branch, and the other end of which is grounded, and the liquid level input terminal is used to obtain the PWM excitation return response signal corresponding to the PWM signal through the third capacitor.

[0009] Optionally, the PWM circuit further includes an eighth resistor and a fourth capacitor. The eighth resistor is located between the second capacitor and the positive input terminal. One end of the fourth capacitor is connected between the eighth resistor and the positive input terminal, and the other end of the fourth capacitor is grounded.

[0010] Optionally, the PWM circuit further includes a first resistor and a second resistor. The PWM output terminal of the control circuit is connected between the first resistor and the second resistor. The first resistor and the second resistor are connected in series to form a second branch. One end of the second branch is connected to the power supply, and the other end of the second branch is connected between the second capacitor and the eighth resistor.

[0011] Optionally, the PWM circuit further includes a fifth capacitor, one end of which is connected between the second capacitor and the liquid level sensor, and the other end of which is grounded.

[0012] Optionally, the reference voltage divider resistor includes a third resistor and a fourth resistor. One end of the third resistor is connected to the power supply, and the other end of the third resistor is connected to the inverting input terminal of the comparator. One end of the fourth resistor is connected to the inverting input terminal, and the other end of the fourth resistor is grounded.

[0013] Optionally, the PWM circuit further includes a fifth resistor, one end of which is connected to the power supply, and the other end of which is connected between the output of the comparator and the control circuit.

[0014] Secondly, this utility model provides a thermal management system, including the above-mentioned liquid level detection device.

[0015] Thirdly, this utility model provides a vehicle including the aforementioned thermal management system.

[0016] The beneficial effects of the liquid level detection device of this utility model are as follows: The liquid level detection device includes a liquid level sensor, a PWM circuit, and a control circuit. The PWM circuit includes a comparator. The non-inverting input terminal of the comparator is connected to the liquid level sensor, and the inverting input terminal of the comparator is provided with a reference voltage divider resistor. The reference voltage divider resistor is used to adjust the reference voltage of the comparator. The output terminal of the comparator is connected to the control circuit. For example, after the liquid level sensor acquires the first liquid level signal under the action of the PWM excitation signal, the comparator of the PWM circuit compares the first liquid level signal with the reference voltage to determine the second liquid level signal. Then, the control circuit can determine the liquid level state according to the second liquid level signal. Since the reference voltage is adjustable, it can adapt to the characteristics or working conditions of different liquid level sensors, thereby improving the ability to distinguish between "empty" and "full" states, and can filter out short-term fluctuation signals when in the "critical state", thus achieving reliable liquid level detection. Attached Figure Description

[0017] Figure 1 This is a structural diagram of the liquid level detection device according to an embodiment of the present invention;

[0018] Figure 2 This is a circuit diagram of the liquid level detection device according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the liquid level state in an embodiment of the present invention. Detailed Implementation

[0020] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Although some embodiments of this utility model are shown in the drawings, it should be understood that this utility model can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this utility model. It should be understood that the drawings and embodiments of this utility model are for illustrative purposes only and are not intended to limit the scope of protection of this utility model.

[0021] It should be understood that the steps described in the method embodiments of this utility model may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this utility model is not limited in this respect.

[0022] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this utility model are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0023] It should be noted that the terms "one" and "multiple" used in this utility model are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0024] The names of the messages or information exchanged between the multiple devices in this embodiment of the invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0025] like Figure 1 As shown in the figure, an embodiment of the present invention provides a liquid level detection device, including a liquid level sensor, a PWM circuit, and a control circuit. The liquid level sensor is configured to be installed in a liquid storage device of a thermal management system. The PWM circuit includes a comparator, the non-inverting input terminal of which is connected to the liquid level sensor, the liquid level sensor being used to receive PWM excitation signals, and a reference voltage divider resistor being provided at the inverting input terminal of the comparator for adjusting the reference voltage of the comparator. The output terminal of the comparator is connected to the control circuit.

[0026] Specifically, the liquid level detection device includes a liquid level sensor, a PWM (PWM signal processing) circuit, and a control circuit. The liquid level sensor can be installed in the liquid storage device of the thermal management system (e.g., pipes and storage containers). The liquid level sensor is connected to the PWM circuit, and the PWM circuit is connected to the control circuit. Figure 2As shown, the PWM circuit includes a comparator. The non-inverting input of the comparator is connected to a liquid level sensor, which receives the PWM excitation signal. A reference voltage divider resistor is located at the inverting input of the comparator to adjust the reference voltage. The output of the comparator is connected to a control circuit (e.g., a microcontroller unit, MCU). A coolant level sensor is also included. After acquiring the first liquid level signal (AD_in), the sensor sends it to the PWM circuit. The PWM circuit compares the first liquid level signal (AD_in) with a reference voltage (which can be adjusted via a reference voltage divider resistor) using a comparator to determine the second liquid level signal (Vin). The second liquid level signal (Vin) is then sent to the control circuit. The control circuit determines the liquid level state based on the second liquid level signal (Vin). A pre-established correspondence between the second liquid level signal and the liquid level state can be established. For example, when the second liquid level signal (Vin) is 0, the coolant level state is identified as "full," and when the second liquid level signal (Vin) is 1, the coolant level state is identified as "empty." Since the reference voltage is adjustable, it can be fine-tuned to adapt to the characteristics or operating conditions of different liquid level sensors (such as changes in temperature and pressure), thereby improving the ability to distinguish between "empty" and "full" states and filtering out short-term fluctuation signals when in a "critical state."

[0027] The control circuit can also compare the first liquid level signal (AD_in) and the second liquid level signal (Vin), which can identify misjudgments caused by sensor drift or acquisition noise, reduce false alarms or missed alarms in the system, and thus verify the accuracy of signal acquisition.

[0028] The coolant level measurement function can request the PWM circuit of the level sensor according to the following parameters: rated amplitude 5V@±0.1V; fixed load 1%@tH=1ms and tL=99ms; frequency 0Hz-10Hz@±1Hz. The adaptive algorithm can adjust in real time according to the coolant level change and external noise coupling. (Because the level sensor in the vehicle environment may be affected by electromagnetic interference, mechanical noise caused by vibration, etc., these noises are usually superimposed on the output signal of the level sensor in the form of fundamental or harmonic waves. By analyzing the noise spectrum characteristics, the frequency of the injected PWM signal is adaptively adjusted to avoid the fundamental or harmonic frequencies in the sensor signal, thereby avoiding interference.)

[0029] In this embodiment, the liquid level detection device includes a liquid level sensor, a PWM circuit, and a control circuit. The PWM circuit includes a comparator, the non-inverting input of which is connected to the liquid level sensor, and a reference voltage divider resistor at the inverting input of the comparator. The reference voltage divider resistor is used to adjust the reference voltage of the comparator. The output of the comparator is connected to the control circuit. After the liquid level sensor acquires the first liquid level signal under the action of the PWM excitation signal, it compares the first liquid level signal with the reference voltage through the comparator of the PWM circuit to determine the second liquid level signal. Thus, the control circuit can determine the liquid level state. Since the reference voltage is adjustable, it can adapt to the characteristics or working conditions of different liquid level sensors, thereby improving the ability to distinguish between "empty" and "full" states, and can filter out short-term fluctuation signals when in a "critical state", thereby achieving reliable liquid level detection.

[0030] Optionally, the liquid level sensor includes a sixth resistor, a seventh resistor, and a first capacitor. The seventh resistor and the first capacitor are connected in series to form a first branch, and the sixth resistor is connected in parallel with the first branch. One end of the sixth resistor and one end of the first branch are both connected to the liquid level output terminal of the PWM circuit. The liquid level output terminal is connected to the positive input terminal of the comparator. The other end of the sixth resistor and the other end of the first branch are both connected to the liquid level input terminal of the PWM circuit.

[0031] Specifically, in combination Figure 2 As shown, the liquid level sensor includes a sixth resistor (Ro), a seventh resistor (Rx), and a first capacitor (Cx). The seventh resistor (Rx) and the first capacitor (Cx) are connected in series to form the first branch. The sixth resistor (Ro) is connected in parallel with the first branch. One end of the sixth resistor (Ro) and one end of the first branch are connected to the liquid level output terminal (Coolant Level out) of the PWM circuit. The liquid level output terminal is connected to the positive input terminal of the comparator. The other end of the sixth resistor (Ro) and the other end of the first branch are connected to the liquid level input terminal (Coolant Level in) of the PWM circuit. When the coolant level changes, Ro / / Cx+Rx changes ( / / indicates parallel connection), and the first liquid level signal (AD_in) changes accordingly.

[0032] Among them, combined Figure 3 As shown, when the water tank is "full", Cx = 1uF to 10uF, Rx = 0.5kΩ to 5kΩ, and Ro = 1MΩ to 5MΩ; when the water tank is "empty", Cx < 50uF, Rx > 60kΩ, and Ro > 5MΩ.

[0033] In this optional embodiment, the liquid level sensor includes a sixth resistor (resistor Ro), a seventh resistor (resistor Rx), and a first capacitor (capacitor Cx). When the coolant level changes, Ro / / Cx+Rx changes, and the first liquid level signal (AD_in) changes accordingly, thereby enabling liquid level detection.

[0034] Optionally, the liquid level output terminal includes a second capacitor, one end of which is connected to one end of the sixth resistor and one end of the first capacitor, and the other end of which is connected to the non-inverting input terminal of the comparator; the liquid level input terminal includes a third capacitor, one end of which is connected to the other end of the sixth resistor and one end of the seventh resistor, and the other end of which is grounded, and the liquid level input terminal is used to obtain the PWM excitation return response signal corresponding to the PWM signal through the third capacitor.

[0035] Specifically, in combination Figure 2 As shown, the liquid level output terminal includes a second capacitor (capacitor Cout, for example, an AC coupling capacitor). One end of the second capacitor (capacitor Cout) is connected to one end of the sixth resistor (resistor Ro) and one end of the first capacitor (capacitor Cx). The other end of the second capacitor (capacitor Cout) is connected to the non-inverting input of the comparator. The liquid level output terminal (CoolantLevel out) can send a PWM excitation output signal to the liquid level sensor through the second capacitor (capacitor Cout). The liquid level input terminal includes a third capacitor (capacitor Cin). One end of the third capacitor (capacitor Cin) is connected to the other end of the sixth resistor (resistor Ro) and one end of the seventh resistor. The other end of the third capacitor (capacitor Cin) is grounded. The liquid level input terminal (CoolantLevel in) obtains the PWM excitation return response signal through the third capacitor (for example, an AC coupling capacitor).

[0036] In this optional embodiment, by setting capacitors at the liquid level output terminal and the liquid level input terminal, DC isolation is achieved to avoid interference from DC voltage on the signal, thereby improving the accuracy of liquid level detection.

[0037] Optionally, the PWM circuit further includes an eighth resistor and a fourth capacitor. The eighth resistor is located between the second capacitor and the positive input terminal. One end of the fourth capacitor is connected between the eighth resistor and the positive input terminal, and the other end of the fourth capacitor is grounded.

[0038] Specifically, in combination Figure 2As shown, the PWM circuit also includes an eighth resistor (R-filter) and a fourth capacitor (C-filter). The eighth resistor (R-filter) is located between the second capacitor and the non-inverting input terminal. One end of the fourth capacitor (C-filter) is connected between the eighth resistor (R-filter) and the non-inverting input terminal, and the other end of the fourth capacitor (C-filter) is grounded. The PWM can be integrated into the AD converter through the eighth resistor (R-filter) and the fourth capacitor (C-filter) as the input signal of the comparator.

[0039] In this optional embodiment, RC filtering using the eighth resistor and the fourth capacitor can reduce noise interference, smooth the input signal, and avoid false triggering due to transient interference or high-frequency noise, thereby improving the stability and accuracy of the comparator.

[0040] Optionally, the PWM circuit further includes a first resistor and a second resistor. The PWM output terminal of the control circuit is connected between the first resistor and the second resistor. The first resistor and the second resistor are connected in series to form a second branch. One end of the second branch is connected to the power supply, and the other end of the second branch is connected between the second capacitor and the eighth resistor.

[0041] Specifically, in combination Figure 2 As shown, the PWM circuit also includes a first resistor (i.e., Figure 2 The control circuit's PWM output terminal (PWM_out) is connected between the first resistor (R1) and the second resistor (R2). The first resistor (R1) and the second resistor (R2) are connected in series to form a second branch. One end of the second branch is connected to the power supply, and the other end of the second branch is connected between the second capacitor (Cout) and the eighth resistor (R-filter). The first resistor (R1) and the second resistor (R2) are excitation voltage divider resistors, pulled up to VCC_5V, used to set the PWM injection voltage amplitude.

[0042] In this optional embodiment, the PWM injection voltage amplitude (corresponding to PWM_out) is set by the first resistor and the second resistor. For example, appropriately increasing the PWM injection voltage amplitude can improve the excitation intensity of the sensor, so that the sensor generates a stronger response signal when the liquid level changes, that is, it can improve the response sensitivity of the sensor.

[0043] Optionally, the PWM circuit further includes a fifth capacitor, one end of which is connected between the second capacitor and the liquid level sensor, and the other end of which is grounded.

[0044] Specifically, in combination Figure 2As shown, the PWM circuit also includes a fifth capacitor (Cesd). One end of the fifth capacitor (Cesd) is connected between the second capacitor (Cout) and the liquid level sensor, and the other end of the fifth capacitor (Cesd) is grounded. The fifth capacitor (Cesd) can achieve functions such as electrostatic protection and can usually withstand transient high voltages (e.g., thousands of volts or more) generated by electrostatic discharge, effectively protecting the back-end circuit.

[0045] Among them, the grounding capacitors mentioned above (the third capacitor, the fourth capacitor, and the fifth capacitor) can be connected in series as two capacitors, so that even if one capacitor is short-circuited, the other capacitor can still work.

[0046] Among them, the grounding capacitors mentioned above (the third capacitor, the fourth capacitor, and the fifth capacitor) can be MLCC (Multilayer Ceramic Capacitor), which can better withstand surge signal impacts and is less prone to short circuits due to its manufacturing process.

[0047] Among them, the grounding capacitors mentioned above (the third capacitor, the fourth capacitor, and the fifth capacitor) can be open-mode capacitors, which will automatically disconnect in the event of a short circuit.

[0048] In this optional embodiment, by setting a fifth capacitor, functions such as electrostatic discharge protection are achieved. It can usually withstand the transient high voltage generated by electrostatic discharge and effectively protect the back-end circuit.

[0049] Optionally, the reference voltage divider resistor includes a third resistor and a fourth resistor. One end of the third resistor is connected to the power supply, and the other end of the third resistor is connected to the inverting input terminal of the comparator. One end of the fourth resistor is connected to the inverting input terminal, and the other end of the fourth resistor is grounded.

[0050] Specifically, in combination Figure 2 As shown, the PWM circuit also includes a third resistor (R3) and a fourth resistor (R4). One end of the third resistor (R3) is connected to the power supply, and the other end is connected to the inverting input of the comparator. One end of the fourth resistor (R4) is connected to the inverting input, and the other end is grounded. The third resistor (R3) and the fourth resistor (R4) serve as a reference voltage divider resistor, which can adjust the reference voltage. For example, changing the resistance values ​​of the third resistor (R3) and the fourth resistor (R4) can adjust the reference voltage.

[0051] In this optional embodiment, the reference voltage can be adjusted by the reference voltage divider resistor to adapt to the characteristics or working conditions of different liquid level sensors, thereby improving the ability to distinguish between "empty" and "full" states, and filtering out short-term fluctuation signals when in a "critical state", thus achieving reliable liquid level detection.

[0052] Optionally, the PWM circuit further includes a fifth resistor, one end of which is connected to the power supply, and the other end of which is connected between the output of the comparator and the control circuit.

[0053] Specifically, in combination Figure 2 As shown, the PWM circuit also includes a fifth resistor (R5). One end of the fifth resistor (R5) is connected to the power supply, and the other end of the fifth resistor (R5) is connected between the output of the comparator and the control circuit. The fifth resistor (R5) acts as a pull-up resistor for the comparator output, which can ensure better measurement of the Vin signal.

[0054] In this optional embodiment, by setting a pull-up resistor at the comparator output, a better measurement of the Vin signal can be ensured.

[0055] Another embodiment of this utility model provides a thermal management system, including the above-mentioned liquid level detection device.

[0056] Another embodiment of this utility model provides a vehicle including the above-described thermal management system.

[0057] Although the present invention has been disclosed above, its protection scope is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the protection scope of the present invention.

Claims

1. A liquid level detection device, characterized in that, The system includes a liquid level sensor, a PWM circuit, and a control circuit. The liquid level sensor is configured to be installed in the liquid storage device of the thermal management system. The PWM circuit includes a comparator, the non-inverting input of which is connected to the liquid level sensor, which is used to receive PWM excitation signals. The inverting input of the comparator is provided with a reference voltage divider resistor, which is used to adjust the reference voltage of the comparator. The output of the comparator is connected to the control circuit.

2. The liquid level detection device according to claim 1, characterized in that, The liquid level sensor includes a sixth resistor, a seventh resistor, and a first capacitor. The seventh resistor and the first capacitor are connected in series to form a first branch, and the sixth resistor is connected in parallel with the first branch. One end of the sixth resistor and one end of the first branch are both connected to the liquid level output terminal of the PWM circuit. The liquid level output terminal is connected to the positive input terminal of the comparator. The other end of the sixth resistor and the other end of the first branch are both connected to the liquid level input terminal of the PWM circuit.

3. The liquid level detection device according to claim 2, characterized in that, The liquid level output terminal includes a second capacitor, one end of which is connected to one end of the sixth resistor and one end of the first branch, and the other end of which is connected to the non-inverting input terminal of the comparator; the liquid level input terminal includes a third capacitor, one end of which is connected to the other end of the sixth resistor and the other end of the first branch, and the other end of which is grounded.

4. The liquid level detection device according to claim 3, characterized in that, The PWM circuit further includes an eighth resistor and a fourth capacitor. The eighth resistor is located between the second capacitor and the positive input terminal. One end of the fourth capacitor is connected between the eighth resistor and the positive input terminal, and the other end of the fourth capacitor is grounded.

5. The liquid level detection device according to claim 4, characterized in that, The PWM circuit also includes a first resistor and a second resistor. The PWM output terminal of the control circuit is connected between the first resistor and the second resistor. The first resistor and the second resistor are connected in series to form a second branch. One end of the second branch is connected to the power supply, and the other end of the second branch is connected between the second capacitor and the eighth resistor.

6. The liquid level detection device according to claim 3, characterized in that, The PWM circuit also includes a fifth capacitor, one end of which is connected between the second capacitor and the liquid level sensor, and the other end of which is grounded.

7. The liquid level detection device according to claim 1, characterized in that, The reference voltage divider resistor includes a third resistor and a fourth resistor. One end of the third resistor is connected to the power supply, and the other end of the third resistor is connected to the inverting input terminal of the comparator. One end of the fourth resistor is connected to the inverting input terminal, and the other end of the fourth resistor is grounded.

8. The liquid level detection device according to claim 1, characterized in that, The PWM circuit also includes a fifth resistor, one end of which is connected to the power supply, and the other end of which is connected between the output of the comparator and the control circuit.

9. A thermal management system, characterized in that, Includes the liquid level detection device according to any one of claims 1 to 8.

10. A vehicle, characterized in that, Includes the thermal management system as described in claim 9.

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