Small-size temperature control switch circuit for vehicle thermal management system

Abstract

The utility model discloses a small-size temperature control switch circuit for a vehicle thermal management system, and relates to the field of automobiles. In the small-size temperature control switch circuit, a voltage dividing network comprises a voltage dividing resistor and a thermistor TR1; the switch module comprises a first MOS (Metal Oxide Semiconductor) tube Q1; the grid electrode of the first MOS tube Q1 is connected with the output of the divider resistor; the voltage dividing network is used for adjusting the voltage applied to the first MOS tube Q1 according to the voltage change at the two ends of the thermistor TR1; the output end is connected with the drain electrode of the first MOS tube Q1; when the first MOS tube Q1 is switched on, the output end outputs electric energy to the vehicle thermal management system, and when the first MOS tube Q1 is switched off, the output end stops outputting the electric energy to the vehicle thermal management system; according to the utility model, the thermistor TR1 is used as a temperature detection element, and the MOS tube is used for forming the temperature control switch, so that the number of required discrete components is reduced, and compared with a complex circuit adopting a low-power-consumption LDO and a special temperature sensor chip in the traditional design, the design greatly simplifies the overall structure.

Description

Technical Field

[0001] This utility model relates to the field of temperature control in vehicle thermal management systems, and more particularly to a small-sized temperature control switch circuit for vehicle thermal management systems. Background Technology

[0002] In vehicles, temperature control switches are primarily used to control the air conditioning and cooling systems to ensure a comfortable interior temperature and maintain the engine within its optimal operating temperature range. Specifically, the temperature control switch maintains a stable interior temperature by regulating the operation of the air conditioning compressor and automatically adjusts the speed of the radiator fan by sensing changes in coolant temperature to prevent the engine from overheating or overcooling, thus extending its lifespan. Traditionally, to achieve low-power and high-precision temperature detection, a complex control circuit consisting of a low-power LDO (low-dropout linear regulator) and a dedicated temperature sensor chip is typically used. However, this approach has several drawbacks: it requires a large number of discrete components, resulting in complex circuitry, larger PCB size, stringent layout and routing requirements, and complex manufacturing processes, thereby increasing production costs and making it unsuitable for large-scale, low-cost production.

[0003] To address the aforementioned issues, this design proposes a simplified temperature control switch solution. By employing an NTC thermistor as the temperature sensing element and using a MOSFET to construct a temperature control switch circuit with temperature sensing functionality, efficient and low-cost temperature control is achieved while reducing the number of discrete components. This design not only features a simple structure and easy layout and wiring but also significantly reduces production costs, making it ideal for mass production and applications. This innovative design effectively solves the problems of high cost and complexity inherent in traditional designs while meeting customer needs. Utility Model Content

[0004] To achieve efficient and low-cost temperature control, this invention proposes a small-sized temperature control switch circuit for a vehicle thermal management system, comprising:

[0005] The input terminal is used to connect to the positive power supply VCC.

[0006] The voltage divider network includes voltage divider resistors and a thermistor TR1, wherein:

[0007] The resistance of thermistor TR1 decreases as the temperature of the vehicle's thermal management system increases, and the change in voltage across its terminals is positively correlated with the change in resistance. When the voltage across thermistor TR1 decreases, the voltage across the voltage divider resistor increases accordingly.

[0008] The power processing module is used to process the positive power supply VCC connected to the input terminal and input the processed power supply to the voltage divider resistor;

[0009] A switching module, which includes a first MOSFET Q1; the gate of the first MOSFET Q1 is connected to the output of a voltage divider resistor;

[0010] The voltage divider network is used to adjust the voltage applied to the first MOSFET Q1 according to the voltage change across the thermistor TR1;

[0011] The output terminal is connected to the drain of the first MOSFET Q1. When the first MOSFET Q1 is turned on, the output terminal outputs electrical energy to the vehicle thermal management system. When the first MOSFET Q1 is turned off, the output terminal stops outputting electrical energy to the vehicle thermal management system.

[0012] Furthermore, the small-sized temperature control switch circuit also includes:

[0013] First protection module: Located at the input terminal, used to clamp the transient voltage below a safe voltage when a transient voltage exceeding a set threshold appears at the input terminal;

[0014] The second protection module is located at the output terminal and is used to clamp the transient voltage below a safe voltage when a transient voltage exceeding a set threshold appears at the output terminal.

[0015] Furthermore, the small-sized temperature control switch circuit also includes:

[0016] The reverse connection protection module, located at the input terminal, is used to prevent the polarity of the positive power supply VCC from being reversed, protecting the circuit from damage caused by reverse power connection.

[0017] Furthermore, the power processing module is electrically connected to the negative terminal of the reverse connection protection module to filter out noise in the power output of the reverse connection protection module and input the filtered power to the voltage divider resistor.

[0018] Furthermore, the first protection module includes a first TVS diode (TVS1); the reverse connection protection module includes a first diode (D1); wherein:

[0019] One end of the first TVS diode TVS1 is connected to the positive power supply VCC, and is then connected to the positive terminal of the first diode D1 and one end of the second protection module in sequence, and then connected to the vehicle thermal management system through the positive terminal OUT+ of the output terminal; the other end of the first TVS diode TVS1 is grounded and connected to the power processing module; the negative terminal of the first diode D1 is connected to the power processing module.

[0020] Furthermore, the power processing module includes:

[0021] The second Zener diode D2, the first capacitor C1, the second capacitor C2, and the fourth resistor R4; wherein:

[0022] One end of the fourth resistor R4 is connected to the negative terminal of the first diode D1, and the other end is connected in sequence to the negative terminal of the second Zener diode D2, one end of the first capacitor C1, and one end of the second capacitor C2, and then connected to one end of the voltage divider network; the positive terminal of the second Zener diode D2 is connected to the other end of the first TVS diode TVS1 and then grounded, and is also connected to the other end of the first capacitor C1 and the other end of the second capacitor C2, and then connected to the other end of the voltage divider network.

[0023] Furthermore, the voltage divider network also includes a third capacitor C3 and a fourth capacitor C4; the voltage divider resistors include: a first resistor R1, a second resistor R2, and a third resistor R3; in the voltage divider network:

[0024] One end of the first resistor R1 is connected to one end of the second capacitor C2 in the power processing module, and the other end is connected to one end of the second resistor R2 and one end of the third resistor R3 in sequence.

[0025] The other end of the second resistor R2 is connected in parallel with the other end of the third resistor R3; the parallel connection of the second resistor R2 and the third resistor R3 is connected to one end of the thermistor TR1.

[0026] One end of the third capacitor C3 is connected in sequence to: the connection end of the thermistor TR1 and the parallel connection end of the second resistor R2 and the third resistor R3, one end of the fourth capacitor C4, and the gate of the first MOS transistor Q1.

[0027] The other end of the third capacitor C3 is connected to the other end of the second capacitor C2 in the power processing module, and is sequentially connected to the other end of the thermistor TR1, the other end of the fourth capacitor C4, and the source of the first MOS transistor Q1.

[0028] Furthermore, the second protection module includes: a second TVS diode TVS2, disposed between the positive terminal OUT+ and the negative terminal OUT- of the output, wherein:

[0029] One end of the second TVS tube TVS2 is connected to the positive terminal of the first diode D1, and is connected to the vehicle thermal management system through the positive terminal OUT+ of the output terminal.

[0030] The other end of the second TVS tube, TVS2, is connected to the drain of the first MOSFET, Q1, and is connected to the vehicle thermal management system through the negative terminal OUT- of the output terminal.

[0031] Furthermore, when the temperature of the vehicle thermal management system rises, the resistance of the thermistor TR1 decreases, resulting in a decrease in the voltage across its terminals, and the voltage applied to the gate of the first MOSFET Q1 decreases accordingly; when the gate voltage is lower than the threshold voltage of the first MOSFET Q1, the first MOSFET Q1 is turned off.

[0032] Furthermore, when the temperature of the vehicle thermal management system decreases, the resistance of the thermistor TR1 increases, causing the voltage across it to rise, and the voltage applied to the gate of the first MOSFET Q1 also increases accordingly; when the gate voltage is higher than the threshold voltage of the first MOSFET Q1, the first MOSFET Q1 is turned on.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] (1) This utility model uses a thermistor TR1 as a temperature sensing element and a MOS transistor to build a temperature control switch, which reduces the number of discrete components required. Compared with the complex circuit of using a low-power LDO and a dedicated temperature sensor chip in the traditional design, this design greatly simplifies the overall structure.

[0035] (2) The simplified circuit design of this utility model not only reduces the component procurement cost, but also reduces the PCB size requirement due to the simpler layout and wiring compared to the traditional design, thereby reducing the production and assembly costs. This makes the design very suitable for large-scale low-cost production and improves market competitiveness.

[0036] (3) Since this utility model reduces the number of discrete components and simplifies the circuit design, it reduces the risk of circuit instability caused by component failure or connection problems, and improves the reliability and stability of the entire temperature control switch circuit.

[0037] (4) The simple design and fewer components of this utility model reduce the complexity of the production process, making production and debugging easier, and also facilitating later maintenance and repair. Attached Figure Description

[0038] Figure 1 This is a circuit diagram of a small-sized temperature control switch for a vehicle thermal management system, according to an embodiment of the present invention. Detailed Implementation

[0039] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0040] Example 1

[0041] To address the issue that traditional designs require a large number of discrete components and complex circuitry, resulting in larger PCB sizes, stringent layout and routing requirements, and complex manufacturing processes, thus increasing production costs and making them unsuitable for large-scale, low-cost production, such as... Figure 1 As shown, this utility model embodiment proposes a small-sized temperature control switch circuit for a vehicle thermal management system, comprising:

[0042] The input terminal is used to connect to the positive power supply VCC.

[0043] First protection module: Located at the input terminal, used to clamp the transient voltage below a safe voltage when a transient voltage exceeding a set threshold appears at the input terminal;

[0044] The reverse connection protection module, located at the input terminal, is used to prevent the polarity of the positive power supply VCC from being reversed, protecting the circuit from damage caused by reverse power connection.

[0045] The first protection module includes a first TVS diode (TVS1); the reverse connection protection module includes a first diode (D1); wherein:

[0046] One end of the first TVS diode TVS1 is connected to the positive power supply VCC, and is then connected to the positive terminal of the first diode D1 and one end of the second protection module in sequence, and then connected to the vehicle thermal management system through the positive terminal OUT+ of the output terminal; the other end of the first TVS diode TVS1 is grounded and connected to the power processing module; the negative terminal of the first diode D1 is connected to the power processing module.

[0047] In this embodiment:

[0048] The first TVS diode, TVS1, is connected between the input terminal and ground to handle transient voltage spikes that appear directly on the VCC power line. These transients may originate from the power supply itself (e.g., voltage fluctuations in a car battery) or external factors (such as lightning strikes, load surges, etc.), protecting the circuit from electrostatic discharge (ESD), lightning strikes, and other transient overvoltage events. Specifically, when a voltage exceeding a predetermined threshold value of the first TVS diode, TVS1, appears on the power line (i.e., the input terminal), the TVS diode quickly turns on, clamping the transient voltage below a safe level, thus protecting downstream circuitry from damage. This safe level is the clamping voltage of the TVS diode, which is slightly higher than the normal operating voltage but far lower than the voltage level that could damage the circuit. TVS diodes have very fast response times, typically in the picosecond to nanosecond range, allowing them to quickly activate the protection mechanism before transient voltages damage sensitive electronic components.

[0049] The first diode, D1, is used to prevent circuit damage caused by incorrect power supply wiring. It also has the function of smoothing out pulse voltages, which can reduce the impact of power supply fluctuations on subsequent circuits.

[0050] The voltage divider network includes voltage divider resistors and a thermistor TR1, wherein:

[0051] The resistance of thermistor TR1 decreases as the temperature of the vehicle's thermal management system increases, and the change in voltage across its terminals is positively correlated with the change in resistance. When the voltage across thermistor TR1 decreases, the voltage across the voltage divider resistor increases accordingly.

[0052] The power processing module is used to process the positive power supply VCC connected to the input terminal and input the processed power supply to the voltage divider resistor;

[0053] The power processing module is electrically connected to the negative terminal of the reverse connection protection module to filter out noise in the power output of the reverse connection protection module and input the filtered power to the voltage divider resistor.

[0054] The power processing module includes:

[0055] The second Zener diode D2, the first capacitor C1, the second capacitor C2, and the fourth resistor R4; wherein:

[0056] One end of the fourth resistor R4 is connected to the negative terminal of the first diode D1, and the other end is connected in sequence to the negative terminal of the second Zener diode D2, one end of the first capacitor C1, and one end of the second capacitor C2, and then connected to one end of the voltage divider network; the positive terminal of the second Zener diode D2 is connected to the other end of the first TVS diode TVS1 and then grounded, and is also connected to the other end of the first capacitor C1 and the other end of the second capacitor C2, and then connected to the other end of the voltage divider network.

[0057] Specifically:

[0058] The second Zener diode D2 is used to stabilize the voltage, ensuring that even if the input voltage fluctuates, the voltage output to the subsequent circuit can remain at a constant level, providing reliable power to the circuit.

[0059] The first capacitor C1 and the second capacitor C2 are used to filter out high-frequency noise and interference in the power supply, ensuring that a clean and stable power supply is provided to the subsequent circuits.

[0060] A switching module, which includes a first MOSFET Q1; the gate of the first MOSFET Q1 is connected to the output of a voltage divider resistor;

[0061] The voltage divider network is used to adjust the voltage applied to the first MOSFET Q1 according to the voltage change across the thermistor TR1;

[0062] The voltage divider network further includes a third capacitor C3 and a fourth capacitor C4; the voltage divider resistors include: a first resistor R1, a second resistor R2, and a third resistor R3; in the voltage divider network:

[0063] One end of the first resistor R1 is connected to one end of the second capacitor C2 in the power processing module, and the other end is connected to one end of the second resistor R2 and one end of the third resistor R3 in sequence.

[0064] The other end of the second resistor R2 is connected in parallel with the other end of the third resistor R3; the parallel connection of the second resistor R2 and the third resistor R3 is connected to one end of the thermistor TR1.

[0065] One end of the third capacitor C3 is connected in sequence to: the connection end of the thermistor TR1 and the parallel connection end of the second resistor R2 and the third resistor R3, one end of the fourth capacitor C4, and the gate of the first MOS transistor Q1.

[0066] The other end of the third capacitor C3 is connected to the other end of the second capacitor C2 in the power processing module, and is sequentially connected to the other end of the thermistor TR1, the other end of the fourth capacitor C4, and the source of the first MOS transistor Q1.

[0067] The output terminal is connected to the drain of the first MOSFET Q1. When the first MOSFET Q1 is turned on, the output terminal outputs electrical energy to the vehicle thermal management system. When the first MOSFET Q1 is turned off, the output terminal stops outputting electrical energy to the vehicle thermal management system.

[0068] The voltage divider network in this invention includes a voltage divider resistor and a thermistor TR1. The resistance of the thermistor TR1 decreases as the temperature of the vehicle's thermal management system increases, and the voltage change across it is positively correlated with the resistance change. When the voltage across the thermistor TR1 decreases, the voltage across the voltage divider resistor increases accordingly. The switching module includes a first MOSFET Q1. The gate of the first MOSFET Q1 is connected to the output of the voltage divider resistor. The voltage divider network is used to adjust the voltage applied to the first MOSFET Q1 according to the voltage change across the thermistor TR1. The output terminal is connected to the drain of the first MOSFET Q1. When the first MOSFET Q1 is turned on, the output terminal outputs electrical energy to the vehicle's thermal management system; when the first MOSFET Q1 is turned off, the output terminal stops outputting electrical energy to the vehicle's thermal management system. In other words, this invention uses an NTC thermistor, i.e., thermistor TR1, as the temperature sensing element and utilizes a MOSFET to build a temperature control switch, reducing the number of discrete components required. Compared to the complex circuits of traditional designs using low-power LDOs and dedicated temperature sensor chips, this design greatly simplifies the overall structure.

[0069] The first MOSFET Q1 acts as a switching element, and its conduction depends on whether the voltage difference between its gate and source exceeds its threshold voltage. When the voltage across the thermistor TR1 (i.e., the voltage applied to the gate of the first MOSFET Q1) is lower than the threshold voltage, Q1 is in the off state, and the output is off; when the voltage across the thermistor TR1 is higher than the threshold voltage, the MOSFET is on, and the output is on. Specifically:

[0070] When the temperature of the vehicle's thermal management system rises, the resistance of the thermistor TR1 decreases, causing the voltage across it to drop, and the voltage applied to the gate of the first MOSFET Q1 decreases accordingly; when the gate voltage is lower than the threshold voltage of the first MOSFET Q1, the first MOSFET Q1 is turned off.

[0071] When the temperature of the vehicle's thermal management system decreases, the resistance of the thermistor TR1 increases, causing the voltage across it to rise, and the voltage applied to the gate of the first MOSFET Q1 also increases accordingly; when the gate voltage is higher than the threshold voltage of the first MOSFET Q1, the first MOSFET Q1 is turned on.

[0072] In this embodiment, the vehicle thermal management system is the vehicle's air conditioning system or cooling system.

[0073] Specifically, for the vehicle's cooling system, this embodiment uses a temperature control switch formed by a voltage divider resistor, a thermistor TR1, and a first MOSFET Q1 to automatically control the on / off state of the cooling fan—that is, the output state to the cooling system—by sensing changes in the temperature of the coolant or the ambient temperature of the cooling system. When the temperature rises, causing the gate voltage to exceed the threshold voltage of the first MOSFET Q1, the temperature control switch triggers the fan to start, thus outputting electrical energy to the cooling system to help reduce the engine temperature. Conversely, if the temperature drops, causing the gate voltage to fall below the threshold voltage of the first MOSFET Q1, the fan is turned off, thus stopping the output to the cooling system to save energy.

[0074] It's important to explain that the temperature detected by the thermistor TR1 depends on its installation location and application. If the thermistor TR1 is placed near the fan or in direct contact with components requiring temperature monitoring, such as the coolant or engine, then it is indeed detecting the temperature of those components. For example, in a cooling system, TR1 might be used to monitor the coolant temperature to determine when to start or stop the fan.

[0075] For the vehicle's air conditioning system, this embodiment uses a temperature control switch formed by a voltage divider resistor, a thermistor TR1, and a first MOSFET Q1 to sense changes in the ambient temperature inside the vehicle and automatically control the operating state of the air conditioning compressor to maintain the interior temperature within a set range. When the interior temperature rises, causing the gate voltage to exceed the threshold voltage of the first MOSFET Q1, the temperature control switch triggers the air conditioning compressor to start, i.e., outputs electrical energy to the air conditioning system to help lower the interior temperature; conversely, if the interior temperature drops, causing the gate voltage to fall below the threshold voltage of the first MOSFET Q1, the air conditioning compressor is turned off, i.e., the output of electrical energy to the air conditioning system is stopped to save energy.

[0076] The temperature detected by the thermistor TR1 depends on its installation location and application. If the thermistor TR1 is placed inside the vehicle cabin or near air conditioning vents, where temperature monitoring is required, then it is indeed detecting the temperature in those areas. For example, in an air conditioning system, an NTC might be used to monitor the air temperature inside the cabin to determine when to start or stop the air conditioning compressor. Specifically:

[0077] Temperature rise: When the temperature inside the vehicle exceeds the set value, the resistance of thermistor TR1 decreases, the voltage across it decreases, while the voltage across the voltage divider resistor increases, resulting in an increase in the voltage applied to the gate of the first MOSFET Q1. When the gate voltage is higher than the threshold voltage of the MOSFET, the MOSFET turns on, the air conditioning compressor starts, and the cooling function begins to work, helping to lower the temperature inside the vehicle.

[0078] Temperature reduction: When the temperature inside the vehicle drops below the set value, the resistance of the thermistor TR1 increases, the voltage across it rises, and the voltage applied to the gate of the first MOSFET Q1 decreases accordingly. When the gate voltage is lower than the threshold voltage of the MOSFET, the MOSFET is turned off, the air conditioning compressor stops working, thereby saving energy and avoiding overcooling.

[0079] It should also be noted that each MOSFET has a specific threshold voltage. The MOSFET will only enter the conduction state when the gate voltage exceeds this threshold voltage, that is, a low impedance path will be established between the source and the drain.

[0080] The characteristic that the resistance of the thermistor TR1 (negative temperature coefficient thermistor) decreases with increasing temperature determines its behavior in the circuit of this embodiment. In this embodiment:

[0081] The thermistor TR1, together with the voltage divider resistors (R1, R2, R3), forms a voltage divider network. This network is used to provide the control voltage for the gate of the first MOSFET Q1. Specifically:

[0082] The resistance of thermistor TR1: When the ambient temperature rises, the resistance of TR1 decreases.

[0083] Changes in the voltage divider network: As the resistance of TR1 decreases, its proportion in the voltage divider network decreases, and therefore the voltage across it also decreases accordingly.

[0084] Gate voltage drop: Since TR1 is connected to ground, its reduced resistance means that the voltage applied to the gate of the first MOSFET Q1 will decrease, because TR1 now bears a smaller voltage drop relative to the overall voltage divider network.

[0085] In this case, as the resistance of TR1 decreases, the gate voltage will also decrease until it falls below the threshold voltage of the MOSFET. At this point, the MOSFET will be turned off, and the output will be shut down.

[0086] A decrease in the resistance of thermistor TR1 will lead to a decrease in the voltage across it in the voltage divider network. It is important to further explain this:

[0087] 1. Total resistance decreases

[0088] The decrease in the resistance of thermistor TR1 leads to a decrease in the total resistance R of the entire voltage divider network. total Decrease. Here, R total =R1+(R2||R TR1 +R3; where R1 represents the resistance of R1, R2 represents the resistance of R2, R3 represents the resistance of R3, and R TR1 This represents the resistance value of TR1, R2||R TR1 This represents the parallel equivalent resistance of R2 and TR1.

[0089] 2. Increased current

[0090] According to Ohm's law, I = V / R, as the total resistance R... total Decreasing the voltage divider will increase the current I through the entire voltage divider network. This is because the supply voltage Vcc remains constant, thus increasing the current.

[0091] 3. Although the current increases as the voltage drop across the thermistor TR1 decreases, the resistance of TR1 decreases significantly. According to the voltage drop formula V0... TR1 =I×R TR1 The voltage drop across the thermistor TR1 is actually reduced. Even with increased current, due to R... TR1 The overall voltage drop is still reduced significantly because the resistance of TR1 changes non-linearly with temperature, and this change is very significant within a certain temperature range. Specifically, the resistance of TR1 (negative temperature coefficient thermistor) decreases significantly with increasing temperature. This is determined by its material properties; the carrier concentration inside the TR1 material increases sharply with increasing temperature, leading to a rapid decrease in resistance. Therefore, the resistance of TR1 drops rapidly when the temperature rises. In other words, the reason why the resistance of TR1 decreases more significantly is due to the combined effect of its material properties and the working principle of the voltage divider network. The non-linear resistance change characteristic of TR1 allows it to rapidly reduce its resistance with increasing temperature, thereby affecting the current distribution and voltage distribution of the entire circuit and ensuring the efficient operation of the system.

[0092] 4. Gate voltage drops

[0093] Since the gate of the first MOSFET Q1 is connected to the node between TR1 and R2, the voltage applied to the gate is the voltage of that node relative to ground. As the resistance of TR1 decreases, the voltage drop across it decreases, and therefore the voltage on the gate also decreases.

[0094] The second protection module is located at the output terminal and is used to clamp the transient voltage below a safe voltage when a transient voltage exceeding a set threshold appears at the output terminal.

[0095] The second protection module includes: a second TVS diode, TVS2, disposed between the positive terminal OUT+ and the negative terminal OUT- of the output, wherein:

[0096] One end of the second TVS tube TVS2 is connected to the positive terminal of the first diode D1, and is connected to the vehicle thermal management system through the positive terminal OUT+ of the output terminal.

[0097] The other end of the second TVS tube, TVS2, is connected to the drain of the first MOSFET, Q1, and is connected to the vehicle thermal management system through the negative terminal OUT- of the output terminal.

[0098] The second protection module is located at the output terminal and is designed to protect the circuitry and vehicle thermal management system from transient overvoltage events. Specifically, when a transient voltage exceeding a set threshold occurs at the output terminal (e.g., a voltage spike caused by load changes, power fluctuations, or external interference), this module responds quickly to clamp the transient voltage below a safe level, preventing these transient voltages from damaging subsequent circuitry or equipment.

[0099] Under normal circumstances, the second TVS diode, TVS2, is in a high-impedance state and does not affect the normal operation of the circuit. When a transient voltage exceeding a set threshold appears at the output terminal, TVS2 quickly turns on, clamping the transient voltage to a safe level. This safe level is the clamping voltage of TVS2, which is slightly higher than the normal operating voltage but far lower than the voltage level that may damage the circuit or equipment. By clamping transient voltages, TVS2 effectively protects subsequent circuits and the vehicle's thermal management system from electrostatic discharge (ESD), lightning strikes, and other transient overvoltage events.

[0100] For different application scenarios:

[0101] In the cooling system, when a transient voltage appears at the output, the second protection module ensures that the cooling fan is not damaged by the overvoltage, thereby ensuring its normal operation and maintaining the engine temperature within a suitable range.

[0102] In air conditioning systems, transient voltages can damage the air conditioning compressor and its control circuits. The second protection module can effectively prevent this from happening, ensuring the stability and reliability of the air conditioning system.

[0103] Through the above design, the second protection module not only provides reliable transient voltage protection, but also enhances the safety and stability of the entire temperature control switch circuit, ensuring that the vehicle thermal management system can operate stably under various working conditions.

[0104] This invention simplifies circuit design, reducing component procurement costs and simplifying PCB size requirements compared to traditional designs. This significantly lowers production and assembly costs, making the design highly suitable for large-scale, low-cost production and enhancing market competitiveness. Furthermore, reducing the number of discrete components and simplifying circuit design effectively reduces the risk of circuit instability due to component failures or connection problems, improving the reliability and stability of the entire temperature control switch circuit. The simple design and fewer components also reduce manufacturing complexity, making production and debugging easier, and facilitating later maintenance and repair. In summary, this invention offers significant advantages in cost reduction, reliability improvement, and simplified production, providing strong support for large-scale applications.

[0105] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0106] Furthermore, in this utility model, the use of terms such as "first," "second," and "a" is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0107] In this utility model, unless otherwise explicitly specified and limited, the terms "connection," "fixing," etc., should be interpreted broadly. For example, "fixing" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0108] Furthermore, the technical solutions of the various embodiments of this utility model can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

Claims

1. A small-sized temperature control switch circuit for a vehicle thermal management system, characterized in that, include: The input terminal is used to connect to the positive power supply VCC. The voltage divider network includes voltage divider resistors and a thermistor TR1, wherein: The resistance of thermistor TR1 decreases as the temperature of the vehicle's thermal management system increases, and the change in voltage across its terminals is positively correlated with the change in resistance. When the voltage across thermistor TR1 decreases, the voltage across the voltage divider resistor increases accordingly. The power processing module is used to process the positive power supply VCC connected to the input terminal and input the processed power supply to the voltage divider resistor; A switching module, which includes a first MOSFET Q1; the gate of the first MOSFET Q1 is connected to the output of a voltage divider resistor; The voltage divider network is used to adjust the voltage applied to the first MOSFET Q1 according to the voltage change across the thermistor TR1; The output terminal is connected to the drain of the first MOSFET Q1. When the first MOSFET Q1 is turned on, the output terminal outputs electrical energy to the vehicle thermal management system. When the first MOSFET Q1 is turned off, the output terminal stops outputting electrical energy to the vehicle thermal management system.

2. The small-size temperature control switch circuit for a vehicle thermal management system according to claim 1, characterized in that, The small-sized temperature control switch circuit also includes: First protection module: Located at the input terminal, used to clamp the transient voltage below a safe voltage when a transient voltage exceeding a set threshold appears at the input terminal; The second protection module is located at the output terminal and is used to clamp the transient voltage below a safe voltage when a transient voltage exceeding a set threshold appears at the output terminal.

3. A small-sized temperature control switch circuit for a vehicle thermal management system according to claim 2, characterized in that, The small-sized temperature control switch circuit also includes: The reverse connection protection module, located at the input terminal, is used to prevent the polarity of the positive power supply VCC from being reversed, protecting the circuit from damage caused by reverse power connection.

4. A small-sized temperature control switch circuit for a vehicle thermal management system according to claim 3, characterized in that, The power processing module is electrically connected to the negative terminal of the reverse connection protection module to filter out noise in the power output of the reverse connection protection module and input the filtered power to the voltage divider resistor.

5. A small-sized temperature control switch circuit for a vehicle thermal management system according to claim 4, characterized in that, The first protection module includes a first TVS diode (TVS1); the reverse connection protection module includes a first diode (D1); wherein: One end of the first TVS diode TVS1 is connected to the positive power supply VCC, and is then connected to the positive terminal of the first diode D1 and one end of the second protection module in sequence, and then connected to the vehicle thermal management system through the positive terminal OUT+ of the output terminal; the other end of the first TVS diode TVS1 is grounded and connected to the power processing module; the negative terminal of the first diode D1 is connected to the power processing module.

6. A small-sized temperature control switch circuit for a vehicle thermal management system according to claim 5, characterized in that, The power processing module includes: The second Zener diode D2, the first capacitor C1, the second capacitor C2, and the fourth resistor R4; wherein: One end of the fourth resistor R4 is connected to the negative terminal of the first diode D1, and the other end is connected in sequence to the negative terminal of the second Zener diode D2, one end of the first capacitor C1, and one end of the second capacitor C2, and then connected to one end of the voltage divider network; the positive terminal of the second Zener diode D2 is connected to the other end of the first TVS diode TVS1 and then grounded, and is also connected to the other end of the first capacitor C1 and the other end of the second capacitor C2, and then connected to the other end of the voltage divider network.

7. A small-sized temperature control switch circuit for a vehicle thermal management system according to claim 6, characterized in that, The voltage divider network further includes a third capacitor C3 and a fourth capacitor C4; the voltage divider resistors include: a first resistor R1, a second resistor R2, and a third resistor R3; in the voltage divider network: One end of the first resistor R1 is connected to one end of the second capacitor C2 in the power processing module, and the other end is connected to one end of the second resistor R2 and one end of the third resistor R3 in sequence. The other end of the second resistor R2 is connected in parallel with the other end of the third resistor R3; the parallel connection of the second resistor R2 and the third resistor R3 is connected to one end of the thermistor TR1. One end of the third capacitor C3 is connected in sequence to: the connection end of the thermistor TR1 and the parallel connection end of the second resistor R2 and the third resistor R3, one end of the fourth capacitor C4, and the gate of the first MOS transistor Q1. The other end of the third capacitor C3 is connected to the other end of the second capacitor C2 in the power processing module, and is sequentially connected to the other end of the thermistor TR1, the other end of the fourth capacitor C4, and the source of the first MOS transistor Q1.

8. A small-sized temperature control switch circuit for a vehicle thermal management system according to claim 7, characterized in that, The second protection module includes: a second TVS diode, TVS2, disposed between the positive terminal OUT+ and the negative terminal OUT- of the output, wherein: One end of the second TVS tube TVS2 is connected to the positive terminal of the first diode D1, and is connected to the vehicle thermal management system through the positive terminal OUT+ of the output terminal. The other end of the second TVS tube, TVS2, is connected to the drain of the first MOSFET, Q1, and is connected to the vehicle thermal management system through the negative terminal OUT- of the output terminal.

9. A small-size temperature control switch circuit for a vehicle thermal management system according to claim 1, characterized in that, When the temperature of the vehicle's thermal management system rises, the resistance of the thermistor TR1 decreases, causing the voltage across it to drop, and the voltage applied to the gate of the first MOSFET Q1 decreases accordingly; when the gate voltage is lower than the threshold voltage of the first MOSFET Q1, the first MOSFET Q1 is turned off.

10. A small-size temperature control switch circuit for a vehicle thermal management system according to claim 1, characterized in that, When the temperature of the vehicle's thermal management system decreases, the resistance of the thermistor TR1 increases, causing the voltage across it to rise, and the voltage applied to the gate of the first MOSFET Q1 also increases accordingly. When the gate voltage is higher than the threshold voltage of the first MOSFET Q1, the first MOSFET Q1 is turned on.

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