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

Abstract

The invention 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; the NTC thermistor, namely 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] The present invention relates to the field of temperature control of a vehicle thermal management system, and in particular to a small-size temperature control switch circuit for a vehicle thermal management system. Background Art

[0002] In vehicles, temperature control switches are mainly used to control air conditioning systems and cooling systems to ensure comfortable temperatures in the car and maintain the engine within the optimal operating temperature range. Specifically, the temperature control switch maintains a stable temperature in the car by regulating the working state of the air conditioning compressor, and automatically adjusts the speed of the cooling fan by sensing the temperature change of the coolant to prevent the engine from overheating or overcooling, thereby extending its service life. In traditional designs, in order to achieve low power consumption and high-precision temperature detection functions, a complex control circuit consisting of a low-power LDO (low-dropout linear regulator) and a dedicated temperature sensor chip is usually used. However, this method has many shortcomings: a large number of discrete components are required, and the circuits are complex, resulting in a large PCB size, high layout and wiring requirements, and complex production processes, which increases production costs and is not suitable for large-scale low-cost production.

[0003] In response to the above problems, this design proposes a simplified temperature control switch solution. By using NTC thermistors as temperature detection elements and using MOS tubes to build temperature control switch circuits with temperature detection functions, efficient and low-cost temperature control is achieved while reducing the number of discrete components. This design is not only simple in structure and easy to layout and wire, but also significantly reduces production costs, making it very suitable for large-scale production and application. This innovative design effectively solves the high cost and complexity problems existing in traditional designs while meeting customer needs. Summary of the invention

[0004] In order to achieve efficient and low-cost temperature control, the present invention proposes a small-size temperature control switch circuit for a vehicle thermal management system, comprising:

[0005] Input terminal, used to connect to the positive power supply VCC;

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

[0007] The resistance of thermistor TR1 decreases as the temperature of the vehicle thermal management system increases, and the voltage change across the thermistor TR1 is positively correlated with the resistance change; when the voltage across the thermistor TR1 decreases, the voltage on the voltage divider resistor increases accordingly;

[0008] A power processing module is used to process the positive power supply VCC connected to the input end and input the processed power supply into the voltage dividing resistor;

[0009] The switch module comprises a first MOS transistor Q1; a gate of the first MOS transistor Q1 is connected to an output of a voltage-dividing resistor;

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

[0011] The output end is connected to the drain of the first MOS tube Q1; when the first MOS tube Q1 is turned on, the output end outputs electric energy to the vehicle thermal management system, and when the first MOS tube Q1 is turned off, the output end stops outputting electric energy to the vehicle thermal management system.

[0012] Furthermore, the small-size temperature-controlled switch circuit further includes:

[0013] The first protection module is arranged at the input end, and is used to clamp the transient voltage below the safe voltage when the transient voltage exceeds the set threshold value at the input end;

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

[0015] Furthermore, the small-size temperature-controlled switch circuit further includes:

[0016] The reverse connection prevention module is set at the input end 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 anti-reverse connection module, and is used to filter out noise in the power output by the anti-reverse connection module, and input the filtered power into the voltage divider resistor.

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

[0019] One end of the first TVS tube TVS1 is connected to the positive power supply VCC, and is connected to the positive end 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 end OUT+ of the output end; the other end of the first TVS tube TVS1 is grounded and connected to the power processing module; the negative end of the first diode D1 is connected to the power processing module.

[0020] Furthermore, the power processing module includes:

[0021] A second voltage stabilizing diode D2, a first capacitor C1, a second capacitor C2 and a fourth resistor R4; wherein:

[0022] One end of the fourth resistor R4 is connected to the cathode end of the first diode D1, and the other end is connected to the cathode end of the second voltage-stabilizing diode D2, one end of the first capacitor C1, and one end of the second capacitor C2 in sequence, and then connected to one end of the voltage-dividing network; the positive end of the second voltage-stabilizing diode D2 is connected to the other end of the first TVS tube TVS1 and then grounded, and is simultaneously 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-dividing network.

[0023] Furthermore, the voltage-dividing network further includes a third capacitor C3 and a fourth capacitor C4; the voltage-dividing resistor includes: a first resistor R1, a second resistor R2 and a third resistor R3; in the voltage-dividing 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 end 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: a connection end of the thermistor TR1 and a parallel end of the second resistor R2 and the third resistor R3, one end of the fourth capacitor C4, and a 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 tube TVS2, which is arranged between the positive terminal OUT+ and the negative terminal OUT- of the output end, 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 end;

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

[0031] Furthermore, when the temperature of the vehicle thermal management system rises, the resistance of the thermistor TR1 decreases, causing the voltage across it to decrease, and the voltage applied to the gate of the first MOS tube Q1 decreases accordingly; when the gate voltage is lower than the threshold voltage of the first MOS tube Q1, the first MOS tube 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 increase, and the voltage applied to the gate of the first MOS tube Q1 also increases accordingly; when the gate voltage is higher than the threshold voltage of the first MOS tube Q1, the first MOS tube Q1 is turned on.

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

[0034] (1) The present invention uses thermistor TR1 as a temperature detection element and uses MOS tubes to form a temperature control switch, thereby reducing the number of discrete components required. Compared with the complex circuit using low-power LDO and dedicated temperature sensor chips in the traditional design, the present design greatly simplifies the overall structure;

[0035] (2) The simplified circuit design of the present invention not only reduces component procurement costs, but also reduces PCB size requirements due to simpler layout and wiring compared to traditional designs, thereby reducing production and assembly costs, making the design very suitable for large-scale low-cost production and improving market competitiveness;

[0036] (3) Since the present invention reduces the number of discrete components and simplifies the circuit design, the risk of circuit instability caused by component failure or connection problems is reduced, and the reliability and stability of the entire temperature control switch circuit are improved;

[0037] (4) The simple design and small number of components of the present invention reduce the complexity of the production process, making production and debugging easier, and also facilitating subsequent maintenance and repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention is a circuit diagram of a small-size temperature control switch for a vehicle thermal management system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0040] Embodiment 1

[0041] In order to solve the problem that the traditional design requires a large number of discrete components and complex circuits, resulting in a large PCB size, high layout and wiring requirements, and complex production processes, which in turn increases production costs and is not suitable for large-scale low-cost production, such as Figure 1 As shown, the embodiment of the present invention provides a small-size temperature control switch circuit for a vehicle thermal management system, comprising:

[0042] Input terminal, used to connect to the positive power supply VCC;

[0043] The first protection module is arranged at the input end, and is used to clamp the transient voltage below the safe voltage when the transient voltage exceeds the set threshold value at the input end;

[0044] The reverse connection prevention module is set at the input end 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 tube TVS1; the anti-reverse connection module includes: a first diode D1; wherein:

[0046] One end of the first TVS tube TVS1 is connected to the positive power supply VCC, and is connected to the positive end 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 end OUT+ of the output end; the other end of the first TVS tube TVS1 is grounded and connected to the power processing module; the negative end of the first diode D1 is connected to the power processing module.

[0047] In this embodiment:

[0048] The first TVS tube TVS1 is connected between the input terminal and the ground to handle transient voltage spikes that appear directly on the VCC power line. These transients may come from the power supply itself (for example, voltage fluctuations of the car battery) or external factors (such as lightning induction, load mutation, etc.), protecting the circuit from electrostatic discharge (ESD), lightning strikes, and other transient overvoltage events. Specifically, when a voltage exceeding the predetermined threshold of the first TVS tube TVS1 appears on the power line (i.e., the input terminal), the TVS tube will quickly turn on and clamp the transient voltage below a safe level, thereby protecting the subsequent circuit from damage. This safety level is the clamping voltage of the TVS tube, which is slightly higher than the normal operating voltage but much lower than the voltage level that may cause damage to the circuit. The TVS tube has a very fast response time, usually in the picosecond to nanosecond level, and can quickly start the protection mechanism before the transient voltage causes damage to sensitive electronic components.

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

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

[0051] The resistance of thermistor TR1 decreases as the temperature of the vehicle thermal management system increases, and the voltage change across the thermistor TR1 is positively correlated with the resistance change; when the voltage across the thermistor TR1 decreases, the voltage on the voltage divider resistor increases accordingly;

[0052] A power processing module is used to process the positive power supply VCC connected to the input end and input the processed power supply into the voltage dividing resistor;

[0053] The power processing module is electrically connected to the negative terminal of the anti-reverse connection module, and is used to filter out the clutter in the power output by the anti-reverse connection module, and input the filtered power into the voltage-dividing resistor.

[0054] The power processing module comprises:

[0055] A second voltage stabilizing diode D2, a first capacitor C1, a second capacitor C2 and a fourth resistor R4; wherein:

[0056] One end of the fourth resistor R4 is connected to the cathode end of the first diode D1, and the other end is connected to the cathode end of the second voltage-stabilizing diode D2, one end of the first capacitor C1, and one end of the second capacitor C2 in sequence, and then connected to one end of the voltage-dividing network; the positive end of the second voltage-stabilizing diode D2 is connected to the other end of the first TVS tube TVS1 and then grounded, and is simultaneously 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-dividing network.

[0057] Specifically:

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

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

[0060] The switch module comprises a first MOS transistor Q1; a gate of the first MOS transistor Q1 is connected to an output of a voltage-dividing resistor;

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

[0062] The voltage divider network also includes a third capacitor C3 and a fourth capacitor C4; the voltage divider resistor includes: 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 end 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: a connection end of the thermistor TR1 and a parallel end of the second resistor R2 and the third resistor R3, one end of the fourth capacitor C4, and a 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 end is connected to the drain of the first MOS tube Q1; when the first MOS tube Q1 is turned on, the output end outputs electric energy to the vehicle thermal management system, and when the first MOS tube Q1 is turned off, the output end stops outputting electric energy to the vehicle thermal management system.

[0068] The voltage-dividing network in the present invention includes a voltage-dividing resistor and a thermistor TR1, wherein: the resistance of the thermistor TR1 decreases as the temperature of the vehicle thermal management system increases, and the voltage change at both ends of the thermistor TR1 is positively correlated with the resistance change; when the voltage at both ends of the thermistor TR1 decreases, the voltage on the voltage-dividing resistor increases accordingly; a switch module, which includes a first MOS tube Q1; the gate of the first MOS tube Q1 is connected to the output of the voltage-dividing resistor; the voltage-dividing network is used to adjust the voltage applied to the first MOS tube Q1 according to the voltage change at both ends of the thermistor TR1; an output end, which is connected to the drain of the first MOS tube Q1; when the first MOS tube Q1 is turned on, the output end outputs electric energy to the vehicle thermal management system, and when the first MOS tube Q1 is turned off, the output end stops outputting electric energy to the vehicle thermal management system; that is, the present invention uses an NTC thermistor, i.e., the thermistor TR1, as a temperature detection element, and uses a MOS tube to form a temperature-controlled switch, thereby reducing the number of discrete components required. Compared with the complex circuit using a low-power LDO and a dedicated temperature sensor chip in a traditional design, the present design greatly simplifies the overall structure.

[0069] The first MOS transistor Q1 is used as a switch element, and whether it is turned on or not depends on whether the voltage difference between the 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 MOS transistor Q1) is lower than the threshold voltage, Q1 is in the cut-off state and the output is turned off; when the voltage across the thermistor TR1 is higher than the threshold voltage, the MOS transistor is turned on and the output is turned on. Specifically:

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

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

[0072] In this embodiment, the vehicle thermal management system is an air conditioning system or a cooling system in the vehicle.

[0073] Specifically, for the vehicle's cooling system, the temperature control switch formed by the voltage divider resistor, thermistor TR1 and the first MOS tube Q1 in this embodiment automatically controls the switching state of the cooling fan, that is, the state of output to the cooling system, by sensing the change in the coolant or the ambient temperature of the cooling system. When the temperature rises, causing the gate voltage to be higher than the threshold voltage of the first MOS tube Q1, the temperature control switch will trigger the fan to start, that is, output electrical energy to the cooling system to help reduce the engine temperature; conversely, if the temperature drops, causing the gate voltage to be lower than the threshold voltage of the first MOS tube Q1, the fan will be turned off, that is, the output to the cooling system will be stopped to save energy.

[0074] It should be explained that the temperature detected by the thermistor TR1 depends on its installation location and application scenario. If the thermistor TR1 is placed near the fan or directly in contact with the coolant, engine and other parts that need to monitor the temperature, then it is indeed detecting the temperature of these parts. For example, in a cooling system, TR1 may be used to monitor the coolant temperature to decide when to start or stop the fan.

[0075] For the vehicle's air conditioning system, the temperature control switch formed by the voltage divider resistor, thermistor TR1 and the first MOS tube Q1 in this embodiment senses the change of the ambient temperature in the vehicle, and automatically controls the working state of the air conditioning compressor to maintain the temperature in the vehicle within the set range. When the temperature in the vehicle rises, causing the gate voltage to be higher than the threshold voltage of the first MOS tube Q1, the temperature control switch will trigger the air conditioning compressor to start, that is, output power to the air conditioning system to help reduce the temperature in the vehicle; conversely, if the temperature in the vehicle drops, causing the gate voltage to be lower than the threshold voltage of the first MOS tube Q1, the air conditioning compressor will be turned off, that is, the output of power to the air conditioning system will be stopped to save energy.

[0076] Since the temperature detected by thermistor TR1 depends on its installation location and application scenario. If thermistor TR1 is placed inside the car or near the air outlet of the air conditioner, etc., where the temperature needs to be monitored, then it is indeed detecting the temperature of these areas. For example, in an air conditioning system, NTC may be used to monitor the air temperature in the car to decide when to start or stop the air conditioning compressor. Specifically:

[0077] Temperature rise: When the temperature in the car rises above the set value, the resistance of thermistor TR1 decreases, the voltage across it decreases, and the voltage on the voltage divider increases, causing the voltage applied to the gate of the first MOS tube Q1 to increase. When the gate voltage is higher than the threshold voltage of the MOS tube, the MOS tube is turned on, the air conditioning compressor starts, and the cooling function starts to work, helping to reduce the temperature in the car.

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

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

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

[0081] Thermistor TR1 and voltage divider resistors (R1, R2, R3) together form a voltage divider network. This network is used to provide a control voltage for the gate of the first MOS tube Q1. Specifically:

[0082] Resistance of thermistor TR1: When the ambient temperature increases, 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 becomes smaller, so the voltage across it also decreases accordingly.

[0084] Gate voltage drops: Since TR1 is connected to the ground side, the reduction in its resistance means that the voltage applied to the gate of the first MOS tube Q1 will drop, because TR1 now bears a smaller voltage drop relative to the total voltage divider network.

[0085] In this case, as the resistance of TR1 decreases, the gate voltage will also decrease until it is lower than the threshold voltage of the MOS tube. At this time, the MOS tube will be cut off and the output will be turned off.

[0086] The reduction in the resistance of thermistor TR1 will cause the voltage across it in the voltage divider network to decrease. Here we need to further explain:

[0087] 1. Total resistance reduction

[0088] The resistance of thermistor TR1 decreases, resulting in a total resistance of the entire voltage divider network R total Here, R total =R 1 +(R 2 ||R TR1 )+R 3 ; Among them, R 1 Represents the resistance value of R1, R 2 Represents the resistance value of R2, R 3 Represents the resistance value of R3, R TR1 Indicates the resistance value of TR1, R 2 ||R TR1 Represents the parallel equivalent resistance of R2 and TR1.

[0089] 2. Current increase

[0090] According to Ohm's law, I = V / R, as the total resistance R total Decreases, and the current I through the entire voltage divider network will increase. Because the power supply voltage Vcc remains unchanged, the current increases.

[0091] 3. The voltage drop on thermistor TR1 decreases. Although the current increases, the resistance of TR1 decreases significantly. According to the voltage drop formula V TR1 =I×R TR1 , the voltage drop across the thermistor TR1 actually decreases. Even though the current increases, due to R TR1 The total voltage drop is still reduced even though the resistance of TR1 resistor changes with temperature in a nonlinear manner, and within a certain temperature range, this change is very significant. Specifically, the resistance of TR1 (negative temperature coefficient thermistor) decreases significantly with increasing temperature, which is determined by its material properties. The carrier concentration inside the TR1 material increases sharply with increasing temperature, resulting in a rapid decrease in resistance. Therefore, when the temperature rises, the resistance of TR1 decreases rapidly. In other words, the reason why the resistance of TR1 decreases more is the result of the combined effect of its material properties and the working principle of the voltage divider network. The nonlinear resistance change characteristic of TR1 enables it to quickly reduce its resistance when the temperature rises, 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 MOS transistor Q1 is connected to the node between TR1 and R2, the voltage applied to the gate will be the voltage of the node relative to the ground. As the resistance of TR1 decreases, the voltage drop across it decreases, so the voltage on the gate also decreases.

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

[0095] The second protection module includes: a second TVS tube TVS2, which is arranged between the positive terminal OUT+ and the negative terminal OUT- of the output end, 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 end;

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

[0098] The second protection module is set at the output end to protect the circuit and the vehicle thermal management system from transient overvoltage events. Specifically, when a transient voltage exceeding the set threshold appears at the output end (such as a voltage spike caused by a sudden load change, power supply fluctuation, or external interference), the module will respond quickly and clamp the transient voltage to a safe level to prevent these transient voltages from damaging subsequent circuits or devices.

[0099] Under normal circumstances, the second TVS tube TVS2 is in a high-resistance state and does not affect the normal operation of the circuit; when a transient voltage exceeding the set threshold appears at the output end, TVS2 quickly turns on to clamp the transient voltage below a safe level. This safety level is the clamping voltage of TVS2, which is slightly higher than the normal operating voltage but much lower than the voltage level that may cause damage to the circuit or equipment; by clamping the transient voltage, TVS2 effectively protects the subsequent circuits and the vehicle 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 transient voltage appears at the output end, the second protection module ensures that the cooling fan will not be damaged by overvoltage, thereby ensuring its normal operation and maintaining the engine temperature within an appropriate range;

[0102] In the air-conditioning system, transient voltage may cause damage to the air-conditioning compressor and its control circuit. The second protection module can effectively prevent this from happening and ensure 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 function, 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] The present invention not only reduces the component procurement cost by simplifying the circuit design, but also reduces the PCB size requirements because the layout and wiring are simpler than the traditional design, thereby significantly reducing the production and assembly costs, making the design very suitable for large-scale low-cost production and improving market competitiveness. In addition, reducing the number of discrete components and simplifying the circuit design effectively reduce the risk of circuit instability caused by component failure or connection problems, and improve the reliability and stability of the entire temperature control switch circuit. The simple design and a small number of components also reduce the complexity of the production process, making production and debugging easier, and also facilitating later maintenance and repair. In summary, the present invention has significant advantages in reducing costs, improving reliability and simplifying production, and provides strong support for large-scale applications.

[0105] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0106] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0107] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0108] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A small-size temperature control switch circuit for a vehicle thermal management system, characterized in that: include: Input terminal, used to connect to the positive power supply VCC; The voltage divider network includes a voltage divider resistor and a thermistor TR1, wherein: The resistance of thermistor TR1 decreases as the temperature of the vehicle thermal management system increases, and the voltage change across the thermistor TR1 is positively correlated with the resistance change; when the voltage across the thermistor TR1 decreases, the voltage on the voltage divider resistor increases accordingly; A power processing module is used to process the positive power supply VCC connected to the input end and input the processed power supply into the voltage dividing resistor; The switch module comprises a first MOS transistor Q1; a gate of the first MOS transistor Q1 is connected to an output of a voltage-dividing resistor; The voltage divider network is used to adjust the voltage applied to the first MOS transistor Q1 according to the voltage change across the thermistor TR1; The output end is connected to the drain of the first MOS tube Q1; when the first MOS tube Q1 is turned on, the output end outputs electric energy to the vehicle thermal management system, and when the first MOS tube Q1 is turned off, the output end stops outputting electric energy to the vehicle thermal management system.

2. A small-size temperature control switch circuit for a vehicle thermal management system according to claim 1, characterized in that: The small-size temperature-controlled switch circuit further includes: The first protection module is arranged at the input end, and is used to clamp the transient voltage below the safe voltage when the transient voltage exceeds the set threshold value at the input end; The second protection module is arranged at the output end, and is used to clamp the transient voltage below the safe voltage when the transient voltage exceeding the set threshold appears at the output end.

3. A small-size temperature control switch circuit for a vehicle thermal management system according to claim 2, characterized in that: The small-size temperature-controlled switch circuit further includes: The reverse connection prevention module is set at the input end 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-size 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 anti-reverse connection module, and is used to filter out the clutter in the power output by the anti-reverse connection module, and input the filtered power into the voltage-dividing resistor.

5. A small-size 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 tube TVS1; the anti-reverse connection module includes: a first diode D1; wherein: One end of the first TVS tube TVS1 is connected to the positive power supply VCC, and is connected to the positive end 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 end OUT+ of the output end; the other end of the first TVS tube TVS1 is grounded and connected to the power processing module; the negative end of the first diode D1 is connected to the power processing module.

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

7. A small-size temperature control switch circuit for a vehicle thermal management system according to claim 6, characterized in that: The voltage divider network also includes a third capacitor C3 and a fourth capacitor C4; the voltage divider resistor includes: 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 end 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: a connection end of the thermistor TR1 and a parallel end of the second resistor R2 and the third resistor R3, one end of the fourth capacitor C4, and a 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. The small-size 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 tube TVS2, which is arranged between the positive terminal OUT+ and the negative terminal OUT- of the output end, 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 end; The other end of the second TVS tube TVS2 is connected to the drain of the first MOS tube Q1 and is connected to the vehicle thermal management system through the negative terminal OUT- of the output end.

9. The 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 thermal management system rises, the resistance of the thermistor TR1 decreases, causing the voltage across it to decrease, and the voltage applied to the gate of the first MOS tube Q1 decreases accordingly; when the gate voltage is lower than the threshold voltage of the first MOS tube Q1, the first MOS tube Q1 is turned off.

10. The 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 thermal management system decreases, the resistance of the thermistor TR1 increases, causing the voltage across it to increase, and the voltage applied to the gate of the first MOS transistor Q1 also increases; When the gate voltage is higher than the threshold voltage of the first MOS transistor Q1 , the first MOS transistor Q1 is turned on.

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