CN116039562A - Automatic defogging system and defogging method for automobile - Google Patents

Abstract

The invention provides an automatic defogging system for an automobile, which comprises an LIN chip, an MCU, a humidity sensitive chip, an NTC thermistor and a high-precision resistor, wherein the LIN chip comprises a 3.3V power module, the LIN chip provides 3.3V voltage for the NTC thermistor, the MCU and the humidity sensitive chip, the high-precision resistor is connected with the NTC thermistor in series, the MCU is communicated with the humidity sensitive chip through an IIC bus, the high-precision resistor is electrically connected with the MCU, the MCU collects the voltage of the high-precision resistor, the MCU is in communication connection with the LIN chip, and the LIN chip is in communication connection with a rear end controller for controlling an air conditioner through an LIN transmission channel. The invention also provides a defogging method of the automatic defogging system of the automobile.

Description

Automatic defogging system and defogging method for automobile

Technical Field

The invention relates to the field of automobile temperature and humidity sensors, in particular to an automatic defogging system and a defogging method thereof.

Background

When the ambient humidity is high or the air temperature is low, the inside of the front windshield of the automobile is liable to be fogged, and the line of sight in front of the driver becomes blurred, and if the vehicle is traveling at this time, the driving safety is seriously affected. Therefore, a new automatic defogging system for the automobile is necessary to be designed, defogging on the inner side of the front windshield is performed in advance, and driving safety is improved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides an automatic defogging system for an automobile and a defogging method thereof, and at least solves part of the problems in the prior art.

The invention is realized in the following way:

the invention provides an automatic defogging system for an automobile, which comprises an LIN chip, an MCU, a humidity sensitive chip, an NTC thermistor and a high-precision resistor, wherein the LIN chip comprises a 3.3V power module, the LIN chip provides 3.3V voltage for the NTC thermistor, the MCU and the humidity sensitive chip, the high-precision resistor is connected with the NTC thermistor in series, the MCU is communicated with the humidity sensitive chip through an IIC bus, the high-precision resistor is electrically connected with the MCU, the MCU collects the voltage of the high-precision resistor, the MCU is in communication connection with the LIN chip, and the LIN chip is in communication connection with a rear end controller for controlling an air conditioner through an LIN transmission channel.

Further, the LIN chip adopts an ATA663231 chip.

Further, the MCU adopts a PIC16F15325 chip.

Further, the humidity sensitive chip adopts an SHT31-DIS chip.

Further, the automatic defogging system of the automobile further comprises a power supply for providing 12V voltage for the LIN chip.

Further, the NTC thermistor is arranged on the FPC flexible circuit board, an opening for the NTC thermistor to directly contact the inner side of the front windshield is formed in the FPC flexible circuit board, and the back surface of the FPC flexible circuit board is tightly attached to the inner side of the front windshield.

The invention also provides a defogging method of the automatic defogging system of the automobile, which comprises the following steps:

s1, an input 12V voltage supplies power to an LIN chip, the LIN chip is provided with a 3.3V power module, and 3.3V voltage generated by the LIN chip supplies power to an NTC thermistor, an MCU and a humidity-sensitive chip;

s2, the MCU is communicated with the humidity-sensitive chip through the IIC bus to acquire a temperature and humidity value detected by the humidity-sensitive chip, and the temperature and humidity value is brought into an algorithm to acquire a dew point temperature according to the algorithm of the dew point temperature;

s3, the high-precision resistor is connected with the NTC thermistor in series, a temperature voltage signal input into the MCU is the voltage of the high-precision resistor, the voltage of the high-precision resistor is divided by the resistance value of the high-precision resistor to obtain the current flowing through the NTC thermistor and the high-precision resistor circuit, the voltage of the high-precision resistor is subtracted by 3.3V to obtain the voltage of the NTC thermistor, the voltage of the NTC thermistor is divided by the current flowing through the NTC thermistor and the high-precision resistor circuit to obtain the resistance value of the NTC thermistor, the RT table is searched, the temperature value corresponding to the resistance value of the NTC thermistor is obtained by the MCU, at the moment, the temperature value corresponding to the resistance value of the NTC thermistor and the dew point temperature are compared, if the temperature value corresponding to the resistance value of the NTC thermistor is larger than the dew point temperature, the fog risk does not exist, and if the temperature value corresponding to the resistance value of the NTC thermistor is equal to or smaller than the dew point temperature, the fog risk exists, and a defogging signal is generated;

s4, the MCU sends a dew point temperature, a temperature value corresponding to the resistance value of the NTC thermistor and a defogging signal or not to the LIN chip;

s5, the LIN chip sends data to the rear-end controller through the LIN transmission channel, and once the rear-end controller obtains a defogging signal, the rear-end controller controls the air conditioner to blow hot air to defog in advance.

The invention has the following beneficial effects:

the invention provides an automatic defogging system for an automobile, which can defog the inner side of a front windshield in advance and improve the driving safety. The invention adopts a novel NTC thermistor mounting structure, so that the temperature of the inner surface of the windshield is detected more accurately, and the defogging control is more accurate.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic block diagram of an automatic defogging system for an automobile according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1, an embodiment of the invention provides an automatic defogging system for an automobile and a defogging method thereof, which comprises a LIN chip (ATA 663231), an MCU (PIC 16F 15325-E/JQ), a humidity sensitive chip (SHT 31-DIS), an NTC thermistor and a high-precision resistor, and fig. 1 is a schematic block diagram of the automatic defogging system for an automobile.

The input 12V voltage supplies power to the LIN chip, the LIN chip is provided with a 3.3V power supply module, the generated 3.3V voltage supplies power to the NTC thermistor, the MCU and the humidity sensitive chip, the high-precision resistor is connected with the NTC thermistor in series,

the MCU is communicated with the humidity sensitive chip through an IIC bus (integrated circuit bus) to acquire a temperature and humidity value detected by the humidity sensitive chip, the temperature and humidity value is brought into the algorithm according to the algorithm of the dew point temperature to acquire the dew point temperature,

the algorithm of the dew point temperature is the prior art, is deduced according to the existing corresponding relation between the temperature and humidity value and the dew point temperature, and is not described in detail,

the temperature voltage signal input to the MCU is the voltage of the high-precision resistor, the voltage of the high-precision resistor is divided by the resistance value of the high-precision resistor to obtain the current flowing through the NTC thermistor and the high-precision resistor circuit, the voltage of the high-precision resistor is subtracted by 3.3V to obtain the voltage of the NTC thermistor, the voltage of the NTC thermistor is divided by the current flowing through the NTC thermistor and the high-precision resistor circuit to obtain the resistance value of the NTC thermistor, the RT table is searched to obtain the temperature value corresponding to the resistance value of the NTC thermistor,

at this moment, the MCU obtains the temperature value and the dew point temperature that the resistance value of NTC thermistor corresponds, compares two values, if the temperature value that the resistance value of NTC thermistor corresponds is greater than dew point temperature, does not have the risk of fogging, if the temperature value that the resistance value of NTC thermistor corresponds is close or is less than dew point temperature, has the risk of fogging, produces defogging signal, MCU sends the defogging signal through RXD, TXD transceiver communication with dew point temperature, the temperature value that the resistance value of NTC thermistor corresponds and have the defogging signal, send LIN chip, LIN chip passes through LIN transmission channel with data transmission to the rear end controller, the rear end controller is in case obtained the defogging signal, and control the air conditioner carries out automatic defogging.

The NTC thermistor is usually arranged on the FPC flexible circuit board, the NTC thermistor is welded on the front surface of the FPC flexible circuit board, the back surface of the FPC flexible circuit board is stuck on the inner side of the front windshield, the FPC flexible circuit board is arranged between the NTC thermistor and the front windshield, the glass temperature cannot be accurately sensed, and the tested temperature data also need to be corrected. According to the invention, the FPC flexible circuit board is subjected to tapping treatment, the NTC thermistor is welded at the tapping position, the back surface of the FPC flexible circuit board is tightly attached to the inner side of the front windshield, the NTC thermistor is ensured to be directly contacted with the inner side of the front windshield through the tapping, and the temperature of the inner side of the front windshield is accurately sensed.

The invention provides a circuit design scheme of an automatic defogging sensor of an automobile, which is characterized in that the temperature and humidity in a cab are detected, then the temperature and humidity value is brought into an algorithm, the foggy dew point temperature is calculated, the temperature of the inner surface of a front windshield is detected, finally judgment is carried out, if the temperature of the inner surface of the front windshield is higher than the dew point temperature, the foggy risk is avoided, and if the temperature of the inner surface of the front windshield is close to or lower than the dew point temperature, the foggy risk exists, and at the moment, an air conditioner is required to blow hot air, and defogging is carried out in advance.

What is not described in detail in this specification is prior art known to those skilled in the art.

The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims (7)

1. An automatic defogging system of car, its characterized in that: the intelligent air conditioner comprises a LIN chip, an MCU, a humidity sensitive chip, an NTC thermistor and a high-precision resistor, wherein the LIN chip comprises a 3.3V power module, the LIN chip provides 3.3V voltage for the NTC thermistor, the MCU and the humidity sensitive chip, the high-precision resistor is connected with the NTC thermistor in series, the MCU is communicated with the humidity sensitive chip through an IIC bus, the high-precision resistor is electrically connected with the MCU, the MCU collects the voltage of the high-precision resistor, the MCU is in communication connection with the LIN chip, and the LIN chip is in communication connection with a rear end controller for controlling the air conditioner through an LIN transmission channel.

2. The automatic defogging system for a vehicle as recited in claim 1, wherein: the LIN chip adopts an ATA663231 chip.

3. The automatic defogging system for a vehicle as recited in claim 1, wherein: the MCU adopts a PIC16F15325 chip.

4. The automatic defogging system for a vehicle as recited in claim 1, wherein: the humidity sensitive chip adopts an SHT31-DIS chip.

5. The automatic defogging system for a vehicle as recited in claim 1, wherein: and a power supply for providing 12V voltage to the LIN chip.

6. The automatic defogging system for a vehicle as recited in claim 1, wherein: the NTC thermistor is arranged on the FPC flexible circuit board, an opening for the NTC thermistor to directly contact the inner side of the front windshield is formed in the FPC flexible circuit board, and the back surface of the FPC flexible circuit board is tightly attached to the inner side of the front windshield.

7. A defogging method for an automatic defogging system of an automobile, comprising:

s1, an input 12V voltage supplies power to an LIN chip, the LIN chip is provided with a 3.3V power module, and 3.3V voltage generated by the LIN chip supplies power to an NTC thermistor, an MCU and a humidity-sensitive chip;

s2, the MCU is communicated with the humidity-sensitive chip through the IIC bus to acquire a temperature and humidity value detected by the humidity-sensitive chip, and the temperature and humidity value is brought into an algorithm to acquire a dew point temperature according to the algorithm of the dew point temperature;

s3, the high-precision resistor is connected with the NTC thermistor in series, a temperature voltage signal input into the MCU is the voltage of the high-precision resistor, the voltage of the high-precision resistor is divided by the resistance value of the high-precision resistor to obtain the current flowing through the NTC thermistor and the high-precision resistor circuit, the voltage of the high-precision resistor is subtracted by 3.3V to obtain the voltage of the NTC thermistor, the voltage of the NTC thermistor is divided by the current flowing through the NTC thermistor and the high-precision resistor circuit to obtain the resistance value of the NTC thermistor, the RT table is searched, the temperature value corresponding to the resistance value of the NTC thermistor is obtained by the MCU, at the moment, the temperature value corresponding to the resistance value of the NTC thermistor and the dew point temperature are compared, if the temperature value corresponding to the resistance value of the NTC thermistor is larger than the dew point temperature, the fog risk does not exist, and if the temperature value corresponding to the resistance value of the NTC thermistor is equal to or smaller than the dew point temperature, the fog risk exists, and a defogging signal is generated;

s4, the MCU sends a dew point temperature, a temperature value corresponding to the resistance value of the NTC thermistor and a defogging signal or not to the LIN chip;

s5, the LIN chip sends data to the rear-end controller through the LIN transmission channel, and once the rear-end controller obtains a defogging signal, the rear-end controller controls the air conditioner to blow hot air to defog in advance.

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