CN1415507A - Intelligent windowscreen wiper - Google Patents

Abstract

The invention discloses a brand-new intelligent wiper, which is characterized in that a specially designed rain sensor is installed on the top of the car in the windward direction to identify and detect the amount of rain (snowflakes, freezing rain) in real time, and the single-chip microcomputer instructs the wiper motor to automatically work at the optimum In the speed (gear) state, the driver can always have a good line of sight without frequent operations. This smart wiper adopts AC anti-stray capacitance rain detection circuit, correlator technology and other means, which has the advantages of reliable operation, strong anti-interference ability, good real-time performance, and high cost performance. It can be widely used in various types of automobiles, speedboats and other corresponding workplaces.

Description

smart wiper

technical field

The invention relates to an intelligent wiper.

Background technique

When the car is running in rainy and snowy days, the front windshield glass will be blurred. In order to ensure that the driver has a good line of sight, a wiper and a washing device are installed on the car. The traditional car wiper is usually controlled by a manual switch to control the speed of the wiper motor or the intermittent working time of the wiper, which increases the driver's operating frequency.

Contents of the invention

The present invention provides an intelligent wiper for the above problems, which can automatically adjust the speed of the wiper motor in time according to the change of rainfall, so as to achieve better control of the wiper; the driver does not need to frequently operate the manual switch of the wiper to maintain a good line of sight .

The technical solution provided by the present invention is: an intelligent wiper, including a wiper, a wiper motor and a transmission mechanism for driving the reciprocating movement of the wiper. The interface circuit, the wiper motor speed control circuit electrically connected with the wiper motor, the output terminal of the rain sensor is connected with the input of the rain signal detection and conditioning circuit, and the rain signal detection and conditioning circuit processes the signal of the rain sensor and outputs a corresponding The signal is sent to the single-chip microcomputer, and the single-chip microcomputer outputs the control signal to control the operation of the speed regulating circuit of the wiper motor through the control interface circuit.

The above-mentioned rain sensor is composed of several capacitor plates connected in parallel and electrically insulated, and bolts that fix the capacitor plates as a whole and are electrically insulated from the capacitor plates.

The rain sensor can also be provided with a casing, and the casing is provided with a rain inlet and a rainwater outlet.

The above rainfall signal detection and conditioning circuit consists of a sine wave oscillator, a capacitance measurement circuit, a sine wave 90-degree phase shifter, a phase-shifted sine wave amplitude adjustment circuit, a comparator and a Smitt trigger to form a sine wave/square wave conversion circuit, analog Composed of a switch and an active low-pass filter, the output of the sine wave oscillator is connected to the input terminal of the capacitance measurement circuit and the 90-degree sine wave phase shifter, and the output terminal of the capacitance measurement circuit and the 90-degree sine wave phase shifter is connected to the analog Switch, the analog switch output is connected to the input terminal of the active low-pass filter.

The present invention can also be provided with a temperature sensor and a detection circuit and a snow melting heating device, wherein the temperature sensor and the detection circuit are composed of a temperature sensor, a voltage reference circuit, a temperature measuring bridge and a comparator, and the temperature sensor causes the output voltage of the temperature measuring bridge The voltage is connected to the input terminal of the comparator, and the output of the voltage reference circuit is used as the working voltage of the temperature measuring bridge.

The above-mentioned snow-melting heating device is composed of four PTC constant-temperature heating sheets and (corresponding) relays formed after waterproof treatment, and the heating sheets are connected to the power supply through the contacts of the relays.

The invention can automatically adjust the speed of the wiper motor in time according to the change of rainfall, thereby realizing the best control of the wiper; and can control the wiper motor to work at the corresponding speed, and the driver can always maintain the best speed without frequently operating the manual switch of the wiper. line of sight. The invention has the advantages of reliable operation, strong anti-interference ability, good real-time performance, high cost performance and the like, and can be widely used in corresponding working occasions such as various automobiles and speedboats.

Description of drawings

Fig. 1 is a block diagram of the present invention;

Fig. 2 is the structural representation of rain sensor of the present invention;

Fig. 3 is the left view of Fig. 2;

Fig. 4 is a rainfall signal detection and conditioning circuit diagram of the present invention;

Fig. 5 is a single-chip microcomputer of the present invention and its control interface circuit diagram;

Fig. 6 is a power supply circuit diagram of the present invention;

Fig. 7 is a working mode switching switch and a speed regulating circuit diagram of the wiper motor of the present invention.

Detailed ways

Taking the three-speed wiper (low speed 27/s, medium speed 36/s, high speed 45/s) as an example, the present invention will be further described in detail in conjunction with the accompanying drawings and embodiments:

Referring to Fig. 1, the present invention comprises rainfall sensor 2, rainfall signal detection and conditioning circuit 3, temperature sensor and detection circuit 1, single-chip microcomputer and its control interface circuit 4, automatic and manual working mode switching switch and wiper motor speed regulating circuit 5, melting Snow heating device 6, single-chip watchdog circuit 7, wiper, motor and transmission mechanism 8 for driving the wiper to reciprocate.

As shown in Fig. 2 and Fig. 3, the core components of the rain sensor 2 of the present invention are 8 groups of capacitors, and the capacitor plates 10 are 16 stainless steel plates with a thickness of 0.5mm, and the multi-sheet capacitor plates 10 are connected in parallel to increase the rainfall capacity. Described rain sensor 2 can also be provided with shell 15, and shell 15 is provided with rain inlet 9 and rainwater outlet 13, is fixedly connected on the shell 15 on multi-chip capacitor plate 10, and capacitor plate 10 passes positive and negative electrode The wirings 16 and 17 are connected with the rainfall signal detection and conditioning circuit 3 . Four bolts 12 electrically insulated from the capacitor plates 10 fix 8 groups of capacitors as a whole, and the structure is arranged in a straight-through type, and the rainwater flowing into the capacitors can flow away from the car roof through the through-type capacitor plates 10 . It can be seen from the principle of capacitors that the capacitance is related to the dielectric constant of the medium between the capacitor plates 10, that is, the capacitance is related to the amount of rainfall. The present invention utilizes the capacitive sensor structure composed of medium (rainfall) to effectively solve the measurement of rainfall, and has the characteristics of high sensitivity, fast response, easy washing and the like.

Rainfall signal detection and conditioning circuit 3 of the present invention (see Fig. 4) is made up of U1D (741) and its peripheral components 10KHZ sine wave oscillator, U11A (OP07) and its peripheral components form the measuring circuit of capacitance Cx in rainfall sensor 2 , U1A (741) and its peripheral components form a sine wave 90-degree phase shifter, U1B (741) and its peripheral components form a phase-shifting sine wave amplitude adjustment circuit, U1C (741) and its peripheral components and Smitt triggers U4A, U4B (CD40106) form a sine wave/square wave conversion circuit. When the wiper working mode switching switch Switch (seeing Fig. 7) was switched to the automatic working state, the circuit of the present invention was just put into operation, as rainfall occurred, the size of the rainfall was converted into the variation of Cx capacitance in real time. The capacitors Cs1 and CS2 connected to both ends of Cx in Fig. 4 are the equivalent stray capacitance between the rain sensor connection cable and the ground. When Rf is large enough, U11A's output voltage Vc=-(Cx*Vi)/Cf, that is, the amplitude of the output sinusoidal AC voltage is proportional to Cx. In this circuit, Cs1 is equivalently connected in parallel with the sine wave signal of U1D, the existence of its equivalent capacitance does not generate a current flowing through Cx to U11A, and the influence on the output of U11A is negligible; Cs2 is connected to the inverting input terminal of U11A and is always In the virtual ground state, its existence will not affect the output of U11A, so the design of this part of the circuit can better suppress the influence of stray capacitance, ensuring the reliability and accuracy of the rainfall measurement results. The output signal of the sine wave oscillator is not only the signal source of the measurement circuit of Cx, but also the reference signal source of the sine wave 90-degree phase shifter. The output is connected to the input terminal of the measurement circuit of the capacitor Cx, and the other is connected to the 90-degree sine wave phase shifter. device input. The sine wave 90-degree phase shifter outputs to the sine wave amplitude adjustment circuit, and after the waveform conversion is completed by the sine wave/square wave conversion circuit, it is output to the switch control terminal of the analog switch U5A (CD4016), and the corresponding input terminal of U5A is measured with the capacitance Cx The output terminals of the circuit are connected, so the sinusoidal signal output by the Cx measurement circuit and the square wave of the same frequency after a phase shift of 90 degrees are used to realize the correlation operation through the analog switch U5A, thereby effectively improving the anti-noise ability of the system. The operation result is input to the active low-pass filter formed by U3 (741) and its peripheral components. The larger the Cx is, the larger the amplitude of the input signal is. The active low-pass filter finally converts the input signal into a level signal output. The greater the amplitude of the input signal, the greater the output level amplitude, so that the rainfall signal detection and conditioning circuit can effectively convert the change of Cx into The size change of the level amplitude. In order to ensure the reliability and accuracy of Cx measurement, this circuit uses a dual power supply operational amplifier chip.

The level output of the active low-pass filter in Fig. 4 is connected with the noninverting input terminals of the three comparators U7A, U7B and U7C (741) in Fig. 5, and the levels of the inverting input terminals of these three comparators are respectively Representing the critical values of small, medium and heavy rain, the output terminals of these three comparators are respectively connected to the corresponding pins P1.0, P1.1 and P1.2 of the microcontroller (80C51). The single-chip microcomputer can judge whether it is raining and the amount of rainfall by inquiring about the level changes of these pins, and output corresponding control signals through the corresponding pins P1.3, P1.4, P1.5 through Q1, Q2 and Q3 are amplified to drive the speed relays CA, CB and CD to make corresponding actions, thereby controlling the opening and speed of the wiper motor. In order to ensure the reliable operation of the single-chip microcomputer, the single-chip microcomputer and its control interface circuit in Figure 5 also use a watchdog circuit 7, which is built with the microprocessor monitoring chip MAX813L as the core, and the control pin of the chip is connected to the P1.7 pin of the single-chip microcomputer , the output pin is connected to the REST pin of the single-chip microcomputer. If the program of the single-chip microcomputer runs away due to various interferences or power failure occurs, MAX813L will output a reset signal to restore the normal operation of the single-chip microcomputer. The wiper device of the present invention is also compatible with the single-chip microcomputer system on the existing automobile.

In view of having only +12V power supply on the car, so the present invention has adopted the power conversion circuit that is made up of U6 (CW34063) and its peripheral components as shown in Figure 6, it transforms +12V input into-12V output, and U9 (7805 ) transforms the +12V input into a +5V output to meet the different needs of the related chips in the system for the power supply voltage.

The wiper motor is the power source of the wiper system. According to its magnetic field structure, it can be divided into two types: wire-wound type and permanent magnet type. The latter has the advantages of small size, light weight, and simple structure. It is widely used in domestic and foreign automobiles. use. In order to achieve the best control purpose, the wiper motor adopts a three-speed permanent magnet motor or a stepless speed regulation motor, and can also use a two-speed motor or change the number of coils connected in series between the positive and negative brushes of the motor to transform the old two The speed motor is a three-speed working mode. In the circuit shown in Figure 7, when the working mode switching switch Switch is switched to the automatic working mode, the +12V power supply, +T and +B are connected, and the wiper stop position control terminal +N and +S are connected. For example, when the rain detection result of the single-chip microcomputer requires the wiper motor to work at low speed, the low-speed relay CA is energized, and its normally open contact CA1 is closed, and the power supply +T passes through +B, CA1, the "+1" terminal of the wiper motor, the wiper motor and ground, When the current enters the motor through the "+1" terminal of the motor, the number of coils connected in series is large, and the motor rotates at a low speed; when the rainfall becomes large, if the rain detection result of the single-chip microcomputer requires the wiper motor to work at a medium speed, the corresponding control signal output by the single-chip microcomputer is cut off first. Open the normally open contact CA1 of the relay CA, and then connect the medium speed relay CB, its normally open contact CB1 is closed, the power supply +T passes through +B, CB1, the "+2" terminal of the wiper motor, the wiper motor and ground, and the current When entering the motor through the "+2" terminal of the motor, the number of coils connected in series is reduced, and the motor rotates at a medium speed; when the rainfall is heavy, the single-chip microcomputer can also command the wiper motor to work at high speed, and the single-chip microcomputer outputs the corresponding control signal and disconnects the relay CB first. The normally open contact CB1 is connected to the high-speed relay CD, and its normally open contact CD1 is closed. At this time, the current enters the motor through the "+3" terminal of the motor, and the number of coils connected in series is the least, and the motor rotates at high speed. When the amount of rain changes from small to large, the single-chip microcomputer controls and increases the speed of the wiper motor in real time; when the rain decreases, the single-chip microcomputer controls the speed of the wiper motor after a delay for a period of time to ensure that the driver has the best line of sight. When the rain stops, the MCU will delay for a while before disconnecting the relays CA, CB and CD. If the wiper fails to swing to the lowest position and stops the driver's sight, the cam switch K in the wiper motor will turn to the left. side, the current passes through K, the +S terminal, +N terminal of the working mode switch, the normally closed switch CA2, CB2 and CD2 of the relay, the "+1" terminal of the wiper motor, the wiper motor and the ground, and the motor continues to rotate at a low speed. When the wiper swings to the lowest position, the cam switch K is automatically turned to the right, the current circuit is disconnected, and the motor stops rotating. The working mode of the wiper motor can also be switched to manual mode, and its working principle is the same as the traditional mode. This smart wiper is also equipped with a washing system. When it is necessary to spray the front windshield glass, turn on the spraying gear in the working mode switch Switch to the "ON" state, and the spraying motor D is put into operation to complete this function.

In order to complete the identification and measurement of snowfall and freezing rain, a temperature sensor 18 (see FIG. 3 ) and a detection circuit (see FIG. 4 ) and a snow melting heating device 6 (see FIG. 7 ) are also provided in the smart wiper. The temperature sensor 18 adopts TD1A, and the response time is less than or equal to 5 seconds in the flowing air. In the circuit, an LM10 chip is used to form a reference circuit to ensure the voltage accuracy of the temperature measuring bridge. The snow-melting heating device 6 is mainly composed of four PTC constant-temperature heating sheets 11 formed after waterproof treatment and corresponding relays. The heating sheet 11 is fixedly connected to the inner side of the sensor housing 15 (see Figures 2 and 3, in order to reduce heat loss, the sensor housing 15 can adopt interlayer, inner folder aluminum silicate particle 14 heat insulations), heating plate 11 links to each other with the power supply on the automobile through the contact of relay. The temperature sensor TD1A installed on the car shell is connected to the non-inverting terminal of the comparator U11. When the outside temperature is lower than 4°C, the comparator U11 outputs a low level to the INT1 terminal of the single-chip microcomputer. The single-chip microcomputer runs the interrupt service program and queries P1. 0, P1.1, P1.2 these pin level changes, if it is judged that there is freezing rain or snowfall, the corresponding control signal will be output through the corresponding pin P1.6 and amplified by Q4, and the relay CN will be energized. Its normally open contact CN1 is closed, the snow-melting heating device 6 works, the temperature of the rain sensor 2 rises rapidly, and the snowfall or freezing rain on the sensor 2 is dissolved into _H2O liquid, and finally the wiper is controlled to the corresponding speed after being processed by the single-chip microcomputer . When the snowfall or freezing rain changes from small to heavy, the speed of the wiper is immediately increased; from large to small, the delay of the speed of the wiper is reduced to ensure a higher scraping rate of the front windshield.

The rain sensor of the present invention can be installed on the top of the car in the windward direction, and is connected with the wiper control circuit part located in the console of the cab by a cable. The change of the rain can change the capacitance of the rain sensor in real time to detect the change of the electrical signal. The electrical signal is provided to the single chip microcomputer after preprocessing (snowflakes and freezing rain can also be converted into changes in capacitance in real time), and the single chip microcomputer controls the wiper motor to work at the optimal speed (stepless speed regulation) or the best speed gear (high , middle and low speed adjustments) to ensure that the driver has a good line of sight.

The present invention adopts means such as AC anti-stray capacitance rainfall detection circuit, correlator technology, etc., and has the advantages of reliable operation, strong anti-interference ability, good real-time performance and high cost performance, and can be widely used in various corresponding working occasions such as automobiles and speedboats.

Claims (10)

1. An intelligent wiper, comprising a wiper, a wiper motor and a transmission mechanism for driving the reciprocating motion of the wiper, characterized in that: a rain sensor, a rain signal detection and conditioning circuit, a single-chip microcomputer and a control interface circuit thereof, and a wiper The motor is electrically connected to the speed control circuit of the wiper motor, and the output terminal of the rain sensor is connected to the input of the rain signal detection and conditioning circuit. After the rain signal detection and conditioning circuit processes the output signal of the rain sensor, it outputs the corresponding signal to the microcontroller The output control signal controls the speed regulation circuit of the wiper motor to work through the control interface circuit. 2. The intelligent windshield wiper according to claim 1, wherein the rain sensor is composed of a plurality of capacitor plates connected in parallel and electrically insulated, and bolts that fix the capacitor plates as a whole and are electrically insulated from the capacitor plates. 3. The intelligent windshield wiper according to claim 2, wherein the rain sensor is provided with a casing, and the casing is provided with a rain inlet and a rainwater outlet. 4. The intelligent wiper according to claim 1, 2 or 3, characterized in that: the rainfall signal detection and conditioning circuit is composed of a sine wave oscillator, a capacitance measurement circuit, a sine wave 90-degree phase shifter, and a phase-shifted sine wave amplitude adjustment The circuit, comparator and Smitt trigger form a sine wave/square wave conversion circuit, an analog switch and an active low-pass filter. The output of the sine wave oscillator is connected to the capacitance measurement circuit and the input end of the sine wave 90-degree phase shifter. The capacitance measuring circuit and the output terminal of the sine wave 90-degree phase shifter are connected to the analog switch, and the output of the analog switch is connected to the input terminal of the active low-pass filter. 5. The intelligent wiper according to claim 1, 2 or 3, characterized in that: a temperature sensor, a detection circuit and a snow melting heating device are provided, wherein the temperature sensor and the detection circuit are composed of a temperature sensor, a voltage reference circuit, a temperature measuring circuit Composed of a bridge and a comparator, the temperature sensor causes a change in the output voltage of the temperature measuring bridge, which is connected to the input of the comparator, and the output of the voltage reference circuit is used as the working voltage of the temperature measuring bridge. 6. The intelligent windshield wiper according to claim 5, characterized in that: the snow-melting heating device is composed of four PTC constant-temperature heating sheets after waterproof treatment and a relay for controlling the heating sheet, and the heating sheet is connected to the power supply through the contact of the relay . 7. The intelligent wiper according to claim 1, 2 or 3, characterized in that: there is a switch for switching the automatic or manual working mode of the wiper. 8. The intelligent windshield wiper according to claim 1, 2 or 3, characterized in that: a single-chip watchdog circuit is provided, and the circuit is built with a microprocessor monitoring chip as the core, and the control pin of the chip is connected to the single-chip I/O The pins are connected, and the output pin is connected with the reset pin of the microcontroller. 9. The intelligent wiper according to claim 1, 2 or 3, characterized in that: the wiper motor speed regulating circuit is composed of a car battery, an ignition switch, a spray washing motor, a working mode switch, a relay and a wiper motor, and the car battery One way is connected to the spray washing motor through the ignition switch, and then through the working mode switch and ground; the other way is connected to the wiper motor through the working mode switching switch and relay. 10. The intelligent wiper according to claim 1, 2 or 3, characterized in that the wiper motor is a three-speed motor, a two-speed motor, a stepless speed regulating motor or an intermittent duty motor.

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