Air quality sensor integrated with temperature detection and detection system

Abstract

This invention proposes an integrated temperature detection air quality sensor and detection system. The air quality sensor includes a MEMS sensor unit and a temperature detection unit. The MEMS sensor unit detects the air quality outside the vehicle and adjusts the heating power consumption. It includes a sensor chip, a MOSFET connected to the sensor chip, and multiple resistors. The sensor chip internally connects a heating circuit and a sensing circuit. The temperature detection unit detects the ambient temperature and includes a thermistor and a resistor and capacitor connected to the thermistor. The air quality detection system includes the aforementioned air quality sensor, an MCU module, a power management module, and a LIN communication module. The MCU module receives the detection signal from the air quality sensor and calculates and controls the heating power consumption of the air quality sensor. The power management module provides a stable operating voltage for the entire detection system. The LIN communication module enables communication between the detection system and other systems in the vehicle. This invention ensures the stability of the sensor module's operating temperature and gas-sensing performance.

Description

Technical Field

[0001] This invention relates to the field of semiconductor sensor technology, and in particular to an air quality sensor and detection system that integrates temperature detection. Background Technology

[0002] With the rapid development of the automotive industry, people's requirements for the air quality inside cars are increasing. Especially in urban environments, due to traffic congestion and environmental pollution, the air quality inside cars is often affected by harmful gases from the outside, such as volatile organic compounds (VOCs), CO, nitrogen oxides (NOx), and NH3. Prolonged exposure to these harmful gases can harm the health of drivers and passengers.

[0003] To improve this situation, the Automatic Air Quality System (AQS) was developed. This system monitors the air quality inside and outside the vehicle in real time. Through a high-sensitivity sensor integrated into the air intake, it accurately detects indicators such as PM2.5 particles and harmful gas concentrations in the outside air. When poor outside air quality is detected, such as in the presence of smog or exhaust pollution, the system automatically activates the recirculation mode to reduce pollutants entering the vehicle. The core component of AQS is the air quality sensor, among which metal-oxide-semiconductor (MOS) AQS sensors have received widespread attention due to their high sensitivity, fast response, and low cost. However, the performance of existing AQS sensors is severely affected in complex operating environments, especially under conditions of significant temperature variations, leading to errors in the detection results. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated temperature detection air quality sensor and detection system for detecting outside air quality and ambient temperature, and performing temperature compensation. This addresses the problem that the performance of existing AQS sensors is severely affected by large temperature variations, leading to errors in the detection results. The specific technical solution is as follows:

[0005] An air quality sensor with integrated temperature detection includes a MEMS sensor unit and a temperature detection unit. The MEMS sensor unit is used to detect the air quality outside the vehicle and adjust the heating power consumption. The temperature detection unit is used to detect the ambient temperature outside the vehicle. The MEMS sensor unit includes a sensor chip, a MOS transistor connected to the sensor chip, and multiple resistors. The sensor chip has a heating circuit and a sensitive circuit connected internally. The temperature detection unit includes a thermistor and a resistor and a capacitor connected to the thermistor.

[0006] Furthermore, the sensor chip is provided with a first pin, a second pin, a third pin, and a fourth pin. A heating resistor is connected between the first pin and the third pin to form a heating circuit. A gas-sensitive resistor is connected between the second pin and the fourth pin to form a sensitive circuit. The first pin and the second pin are respectively connected to a first resistor and a second resistor and then connected to the VCC terminal. The third pin is connected to the MOSFET. The MOSFET is connected to the third resistor and the fourth resistor and then connected to the PWM terminal. The fourth pin is connected to ground.

[0007] Furthermore, the thermistor and the fifth resistor are connected in series, the thermistor is connected in parallel with the first capacitor, and the common connection terminal of the thermistor, the fifth resistor, and the first capacitor is connected to the NTC terminal.

[0008] Furthermore, the sensor chip includes at least one of a MEMS carbon monoxide sensor chip, a MEMS ammonia sensor chip, or a MEMS nitrogen dioxide sensor chip.

[0009] Furthermore, the air quality sensor includes multiple MEMS sensor units, which employ different types of sensor chips.

[0010] This invention also provides an air quality detection system with integrated temperature detection, including the aforementioned air quality sensor with integrated temperature detection, and further including an MCU module, a power management module, and an LIN communication module. The air quality sensor, the power management module, and the LIN communication module are all connected to the MCU module. The air quality sensor is used to detect the air quality and ambient temperature outside the vehicle. The MCU module is used to receive the detection signal from the air quality sensor and simultaneously calculate and control the heating power consumption of the air quality sensor. The power management module is used to provide a stable operating voltage for the entire detection system. The communication module is used for the detection system to communicate with other systems in the vehicle and provide the obtained air quality values ​​to other systems for corresponding processing.

[0011] Furthermore, the first pin, second pin, PWM terminal, and NTC terminal of the air quality sensor are connected to the MCU module. The MCU module can obtain the power consumption of the heating circuit in real time by acquiring the voltage signal of the first pin. The MCU module can obtain the corresponding gas concentration by acquiring the voltage signal of the second pin and the characteristics of the thermistor. The MCU module can obtain the current ambient temperature by acquiring the voltage signal of the NTC terminal and the characteristics of the thermistor. The MCU module uses a PID algorithm to calculate based on the current ambient temperature and outputs a PWM wave with an adjustable duty cycle to control the on / off state of the heating circuit, thereby adjusting the heating power consumption and allowing the sensor chip to operate within a suitable temperature range.

[0012] Furthermore, the LIN communication module includes a LIN communication chip and resistors, capacitors, inductors, and ESD diodes connected to the LIN communication chip.

[0013] Furthermore, the power management module includes a TVS diode, a rectifier diode, an inductor, and multiple capacitors connected to the power input terminal, and also includes a power management chip and an inductor and multiple capacitors connected to the power management chip.

[0014] This invention provides an integrated temperature detection air quality sensor and detection system, which has the following features:

[0015] Beneficial effects:

[0016] This invention provides an integrated temperature detection air quality sensor and detection system that integrates air quality detection, temperature detection, and temperature compensation into one unit. It has a built-in NTC temperature sensor and automatically realizes temperature compensation. By modulating power consumption with PWM, it realizes different temperature power consumption of various gas sensor chips, ensuring the stability of the sensor module's operating temperature and gas sensing performance. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the internal circuit structure of an air quality sensor that integrates temperature detection.

[0018] Figure 2 This is a schematic diagram of an air quality monitoring system that integrates temperature detection.

[0019] Figure 3 This is a partial schematic diagram of an air quality monitoring system that integrates temperature detection.

[0020] Figure 4 This is a partial schematic diagram of an air quality monitoring system that integrates temperature detection. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clearly illustrate the purpose of the embodiments of the present invention.

[0022] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connection" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0023] In the description of this invention, terms such as "upper," "lower," "left," "right," "front," "back," "center," "horizontal," "vertical," "top," "bottom," "inner," and "outer," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0024] Example 1: This example provides an air quality sensor with integrated temperature detection. (See attached document.) Figure 1 As shown, this air quality sensor integrates a MEMS sensor unit and a temperature detection unit. The MEMS sensor unit detects the air quality outside the vehicle and adjusts heating power consumption, while the temperature detection unit detects the ambient temperature. This air quality sensor ensures the stability of the sensor module's operating temperature and gas-sensing performance.

[0025] The following is a detailed description of the air quality sensor with temperature compensation.

[0026] As a specific implementation of a MEMS sensor unit, the MEMS sensor unit includes a sensor chip U1, a MOSFET, and multiple resistors, including a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The sensor chip U1 has a first pin 1, a second pin 2, a third pin 3, and a fourth pin 4. The sensor chip U1 internally includes a heating resistor R. H and sensitive resistor R S Heating resistance R H A heating circuit is formed between the first pin 1 and the third pin 3 of the sensor chip U1, and the sensitive resistor R SA sensitive circuit is formed between pin 2 and pin 4 of sensor chip U1. One end of the first resistor R1 is connected to pin 1 of the heating circuit of sensor chip U1, and the other end is connected to VCC. One end of the second resistor R2 is connected to pin 2 of the sensitive circuit of sensor chip U1, and the other end is connected to VCC. The drain of the MOSFET is connected to pin 3 of the heating circuit of sensor chip U1. One end of the source of the MOSFET is connected to ground, and the other end is connected to the gate of the MOSFET. One end of the third resistor R3 is connected to the gate of the MOSFET, and the other end is connected to ground. One end of the fourth resistor R4 is connected to the gate of the MOSFET, and the other end is connected to the PWM port. Pin 4 of sensor chip U1 is grounded.

[0027] In a MEMS sensor unit, resistor R1 and heating resistor R H Connected in series, making the heating resistor R H The voltage at pin 2 is maintained at a suitable operating voltage, while the MOSFET controls the circuit's on / off state to keep the chip operating at a stable and suitable temperature. By acquiring the voltage at pin 2, the corresponding gas concentration can be obtained based on the characteristic curve of the sensitive material.

[0028] As one specific implementation of the temperature detection unit, the temperature detection unit includes a fifth resistor R5, a thermistor RT, and a first capacitor C1. The fifth resistor R5 and the thermistor RT are connected in series. The other end of the fifth resistor R5 is connected to the VCC terminal. The thermistor RT is connected to ground. The first capacitor C1 is connected in series with the thermistor RT. The common terminal of the fifth resistor R5, the thermistor RT, and the capacitor C1 is connected to the NTC port.

[0029] Preferably, the air quality sensor may include multiple MEMS sensor units, each employing a different type of sensor chip. Each sensor chip is connected to a heating circuit and a sensing circuit, enabling the detection of multiple toxic and harmful gases. For example, if the air quality sensor includes three MEMS sensor units, with sensor chips for carbon monoxide, ammonia, and nitrogen dioxide respectively, and each of these three sensor chips is connected to a heating circuit and a sensing circuit, then the air quality sensor can simultaneously detect three toxic and harmful gases: CO, NOx, and NH3.

[0030] Example 2: This example provides an air quality detection system with integrated temperature detection. (See attached document.) Figure 2As shown, the system includes not only the air quality sensor provided in Embodiment 1, but also an MCU module, a communication module, and a power management module. The air quality sensor detects the air quality and temperature outside the vehicle. The MCU module receives the detection signal from the air quality sensor and simultaneously calculates and adjusts the heating power consumption to eliminate the impact of ambient temperature changes on the sensor chip. The power management module provides a stable operating voltage for the entire air quality detection system. The communication module enables the air quality detection system to communicate with other systems in the vehicle, providing the obtained air quality values ​​to these other systems for appropriate processing.

[0031] As one specific implementation of the communication module, see [link / reference]. Figure 3 As shown, the communication module includes a LIN communication chip U2, a sixth resistor R6, a second capacitor C2, a first inductor L1, and an ESD diode D1. One end of the sixth resistor R6 is connected to VCC, and the other end is connected to the RXD pin of the LIN communication chip U2. One end of the second capacitor C2 is connected to ground, and the other end is connected to the output terminal of the LIN communication chip U2 and the first inductor L1. The other end of the first inductor L1 is connected to the ESD diode D1, and the other end of the ESD diode D1 is connected to ground. The remaining pins of the LIN communication chip U2 are connected to the corresponding pins in the MCU module.

[0032] As one specific implementation of the power management module, see [link / reference]. Figure 4 As shown, the power management module includes a TVS diode D2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, a rectifier diode D3, a second inductor L2, a power management chip U3, a seventh resistor R7, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, and a third inductor L3. Specifically, the TVS diode D2 is connected in parallel with the third capacitor C3 and the fourth capacitor C4, with one end of its common terminal connected to ground and the other end connected to the power input terminal. One end of the rectifier diode D3, together with the common terminal of the TVS diode D2, the third capacitor C3, and the fourth capacitor C4, is connected to the power input terminal, and the other end is connected to the second inductor L2. The common connection terminal of the rectifier diode D3 and the second inductor L2 is connected to ground through the fifth capacitor C5. The other end of the second inductor L2 is connected to the sixth capacitor C6 and the seventh capacitor C7, which are connected in parallel to ground, and is also connected to the power input terminals of the LIN communication chip U2 and the power management chip U3. The output of power management chip U3 is first connected to the eighth capacitor C8 and the ninth capacitor C9, which are connected in parallel to ground. Then, it is connected to the third inductor L3. The other end of the third inductor L3 is connected to one end of the tenth capacitor C10, which simultaneously outputs a stable VCC. The other end of the tenth capacitor C10 is connected to ground. The EN pin of power management chip U3 is connected to the seventh resistor R7, and the other end of the seventh resistor R7 is connected to ground.

[0033] Optionally, the MCU module can be a BAT32 series microcontroller. The MCU control circuit is existing technology and will not be described in detail here.

[0034] Connect the first pin 1, second pin 2, and PWM terminal of the MEMS sensor unit in the air quality sensor, as well as the NTC terminal of the temperature detection unit, to the microcontroller of the MCU module. The microcontroller can obtain the corresponding gas concentration by acquiring the voltage signal at the second pin 2 of the sensitive circuit and the characteristics of the gas-sensitive material. It can also obtain the power consumption of the heating circuit in real time by acquiring the voltage signal at the first pin 1 of the heating circuit, and obtain the current ambient temperature by acquiring the voltage signal at the NTC terminal of the temperature detection unit and the characteristics of the thermistor. The MCU module performs a PID algorithm based on the current temperature and outputs a PWM wave with an adjustable duty cycle to control the on / off state of the heating circuit, thereby adjusting the heating power consumption and keeping the chip operating within a suitable temperature range to eliminate the influence of ambient temperature changes on the sensor chip.

[0035] Those skilled in the art should understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the invention. Any changes or modifications made by those skilled in the art based on the embodiments of the present invention and the above disclosure shall fall within the protection scope of the claims.

Claims

1. An air quality sensor integrating temperature detection, characterized in that: The system includes a MEMS sensor unit and a temperature detection unit. The MEMS sensor unit is used to detect the air quality outside the vehicle and adjust the heating power consumption. The temperature detection unit is used to detect the ambient temperature outside the vehicle. The MEMS sensor unit includes a sensor chip, a MOS transistor connected to the sensor chip, and multiple resistors. The sensor chip has a heating circuit and a sensitive circuit connected inside. The temperature detection unit includes a thermistor and a resistor and a capacitor connected to the thermistor. The sensor chip is provided with a first pin, a second pin, a third pin, and a fourth pin. A heating resistor is connected between the first pin and the third pin to form a heating circuit. A gas-sensitive resistor is connected between the second pin and the fourth pin to form a sensitive circuit. The first pin and the second pin are respectively connected to the first resistor and the second resistor and then connected to the VCC terminal. The third pin is connected to the MOSFET. The MOSFET is connected to the third resistor and the fourth resistor and then connected to the PWM terminal. The fourth pin is connected to ground. The thermistor and the fifth resistor are connected in series, the thermistor is connected in parallel with the first capacitor, and the common connection terminal of the thermistor, the fifth resistor, and the first capacitor is connected to the NTC terminal.

2. The air quality sensor with integrated temperature detection according to claim 1, characterized in that: The sensor chip includes at least one of a MEMS carbon monoxide sensor chip, a MEMS ammonia sensor chip, or a MEMS nitrogen dioxide sensor chip.

3. The air quality sensor with integrated temperature detection according to claim 2, characterized in that: The air quality sensor includes multiple MEMS sensor units, which employ different types of sensor chips.

4. An air quality detection system with integrated temperature detection, comprising an air quality sensor with integrated temperature detection as described in any one of claims 1-3, characterized in that: It also includes an MCU module, a power management module, and a LIN communication module. The air quality sensor, the power management module, and the LIN communication module are all connected to the MCU module. The air quality sensor is used to detect the air quality and ambient temperature outside the vehicle. The MCU module is used to receive the detection signal from the air quality sensor and simultaneously calculate and control the heating power consumption of the air quality sensor. The power management module is used to provide a stable operating voltage for the entire detection system. The LIN communication module is used for the detection system to communicate with other systems in the vehicle and provide the obtained air quality values ​​to other systems for corresponding processing.

5. The air quality detection system with integrated temperature detection according to claim 4, characterized in that: The first pin, second pin, PWM terminal, and NTC terminal of the air quality sensor are connected to the MCU module. The MCU module can obtain the power consumption of the heating circuit in real time by acquiring the voltage signal of the first pin. The MCU module can obtain the corresponding gas concentration by acquiring the voltage signal of the second pin and the characteristics of the thermistor. The MCU module can obtain the current ambient temperature by acquiring the voltage signal of the NTC terminal and the characteristics of the thermistor. The MCU module uses a PID algorithm to calculate based on the current ambient temperature and outputs a PWM wave with an adjustable duty cycle to control the on / off state of the heating circuit, thereby adjusting the heating power consumption and allowing the sensor chip to operate within a suitable temperature range.

6. The air quality detection system with integrated temperature detection according to claim 4, characterized in that: The LIN communication module includes a LIN communication chip and resistors, capacitors, inductors, and ESD diodes connected to the LIN communication chip.

7. The air quality detection system with integrated temperature detection according to claim 4, characterized in that: The power management module includes a TVS diode, a rectifier diode, an inductor, and multiple capacitors connected to the power input terminal, and also includes a power management chip and an inductor and multiple capacitors connected to the power management chip.

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