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If the car has a rain sensor, the driver does not need to adjust the wiper settings to quickly stop the wiper blade movement or get a better viewing angle. When driving on a wet road, the driver does not need to open the wiper, so the driver can concentrate on driving. If an additional "auxiliary lamp switch" is installed, the lamp will be turned on in the dim timeout condition, and no fuel will be wasted because the lamp is always on. Most current models use a single motor driven wiper system. The advantages of this system are self-evident, the use of a linkage mechanism to drive two wipers, the cost is relatively low. However, the noise of the wiper and the phenomenon of uncleanness in the rain and snow weather still occur from time to time.

1. Working principle of rain sensor:

Most rain sensors use an optical system consisting of a light emitting diode (LED), a light receiving diode (LRD), a surrounding environment sensor, an electric control unit (ECU), and several lenses.

The light emitted by the LED is reflected on the outer surface of the windshield at a total reflection angle, and the angle must be between 420 (glass-air) and 630 (glass-water). If it is said that upstream of the windshield, some light will be emitted twice, and this will cause the current from the LRD to decrease. The current is evaluated electronically, and the light emitted from the LED is reflected to the windshield area of ​​the LRD

This is called the "sensitive area" of the sensor. Only when rain drops reach this area can it be detected. In order to have a sensitive and reliable system, there must be a good ratio between the windshield area and the sensitive area.

2. Auto wiper system

Automobile windshield wiper system is composed of rain sensor, wiper motor, lever switch, relay and ECU. The rain sensor is installed on the windshield. When detecting rain in the sweeping area, the wiper moves with a good angle of view that allows the driver to always have a good perspective. There are two different systems.

1. Independent rainwater system: In this system, the rainwater sensor is directly connected to the wiper lever switch, wiper motor relay and wiper motor stop signal.

2. Network rain sensor: In this system, the rain sensor is connected to the bus, and it receives all information and sends all commands through the network.

After the driver turns on the system, the rain sensor controls all the sweeping behavior. It will command a single wiper to sweep at a low speed or sweep at a high speed. Because each driver has different expectations about how the wiper system is reflected, the sensitivity setting can make the system meet different needs of drivers. Bosch's new wiper motor can continuously sweep with changing speed.

Three, signal evaluation

1. Launcher

The transmitter consists of an analog-to-digital converter (DAC) and a power supply. The analog voltage control of the DAC determines the intensity of the light emitted by the LED. Generally, 2 to 4 LEDs are used. The current regulation of the transmitter is very important because the effectiveness of light conversion is very variable and has a temperature gradient. Generally, in LEDs, light is emitted in a pulsating manner to reduce losses and increase current. Another reason for using a wide range of emitter currents is that the emission of light through the windshield is not well regulated and has a large tolerance range. General windshields are 4-6mm thick and have a specific emission level for IR perpendicular to the surface. Different suppliers have different upper and lower time limits.

2. Receiver

The receiver consists of several LRDs, current-to-voltage converters, filters for clearing or low frequency offset, amplifiers, and ADCs. It generally also includes a microcontroller. LRD has a microcontroller which is controlled by the microcontroller to turn on and off. in case

When there is interference light, the LRD will be turned off. The wide range of emissions is the reason for using variable current-voltage conversion to ensure that the rest of the receiver system is in good condition. After the conversion, fortunately it was filtered. All DC or low frequency interference will be removed to obtain a pure signal. The interference is generally caused by the light in the surrounding environment. The amount of interference is measured by the microcontroller to determine whether the light path is satisfactory or saturated by sunlight, and will give a signal accuracy indication. The filtered signal is amplified and converted by the ADC.

3. Microcontroller

The microcontroller controls the entire system and evaluates the signal. Before the measurement is performed, the best working point is evaluated. Carry out the test with the test. The conversion ratio in the receiver is the least desirable to have a saturated signal in the ADC with the largest transmit current. After the emission current is evaluated, it generates a signal in the receiver. It is between the defined upper and lower limits. The upper limit is determined by the saturation effect and not by the accuracy of the ADC. The sensor starts to work at the operating point. Interference and signals are constantly being measured and evaluated. The gradient of the received signal over time is used by the rule system to evaluate the correct sweeping strategy, and the surrounding light is measured by an additional sensor to detect day or night conditions. At night, because water droplets have a greater impact on visibility, especially if the bright headlights of other vehicles are illuminated, the sensitivity will increase.

4. Sweep mode

Different sweeping modes are used to optimize the performance of all rain conditions, and the wiper speed mode for rain density is shown in the figure.

1. Direct mode

In the direct mode, there is a single wiping action at a low wiper speed. This is the most basic working state when the automatic mode is on and when the system detects a dry windshield. From this state, each rain event will directly trigger a single wiping movement. During the wiping process, the system decides to stop, continue wiping, or switch to high-speed wiping at a low speed.

2. Intermittent mode

This mode is for rainy conditions and runs a single wipe at low speed. Every few seconds, the sensor will detect raindrops, the time between two rains determines the interval between two single wipes. At the end of each interval, the time will be recalculated. The more rain, the shorter the interval, and vice versa. In the calculation, the previous pause will be taken into account to achieve a harmonious state. Otherwise, "nervous behavior" will annoy the driver. If the calculated pause is longer than the maximum pause, the system will switch to direct mode. In each wiping cycle, the sensor checks to decide whether to switch or continue wiping.

3. Wipe continuously

During the wiping cycle, the number of rains will be calculated and the size of the raindrops will be evaluated, which is used to obtain information on the intensity of the rain. According to this intensity, the rain sensor will produce a low speed, high speed or a specific wiping speed (such as 50r / min). Dynamic lag, which relies on this event in the final cycle, will prevent the system from quickly switching from one speed to another. Use the time reference of the wiper motor stop signal to ensure correct operation of all wiper motors under all conditions. If the motor wipes at a low speed, the detection time is reduced and the threshold between low and high speed is automatically increased. The rain sensor mode always reduces the speed from high speed to low speed before stopping to prevent the wiper from generating mechanical stress.

Vibratory Motor

Xinxiang Mina Import & Export Co., Ltd. , https://www.mina-motor.cn