Car window closer. Free Technical Library article

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Car window closer

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Encyclopedia of radio electronics and electrical engineering / Automobile. Electronic devices

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On sale now you can find imported devices that manufacturers call "modules for the movement of car windows in one direction." They are automatic electronic units that raise the side windows of the car when it is armed. The relatively high cost of such modules and the desire to equip your car with additional functions prompted the author of this article to independently develop such a device, which received a shorter name from Russian motorists - a glass closer. The closer is designed to alternately close the four door windows of the passenger compartment and the upper hatch (the priority is selected by the user when connected) when the security alarm installed on the vehicle switches to the armed mode. The command to turn on the electric motors of the power windows is a signal that comes in the form of a pulse with a duration of 1 s from the output of the security alarm and is intended to control the central lock of the car.

Depending on the car model, the active voltage level of the central lock control signal can be either high (close to 12 V) or low (close to zero) relative to the common wire. To do this, the closer has two input contacts, the choice of one of which depends on the level of the control pulse. Another pair of contacts of the input connector is provided for receiving a pulse from a security alarm to interrupt the operation of the window lift mechanisms (for the ignition lock, this pulse serves as a command to unlock the passenger compartment doors). One pin of this pair is for the active high pulse, and the other is for the active low pulse. The interruption allows you to stop the operation of the power window mechanisms at any time, for example, if a child left in the car is in the window opening.

Also, a signal from the ignition switch when the key is in the first position (“ACC” - battery) and from the door limit switches can serve as a prohibition to start the operation of the window lift mechanisms. With the doors open, the signal on the corresponding pin of the closer input connector should be low. The motor rotor of each power window mechanism rotates until the glass is raised to the stop, after which it stops. When the rotor rotates, an alternating voltage component appears in the vehicle's on-board network, which occurs due to the peculiarities of the operation of the electric motor collector. As soon as the rotor stops, the variable component will disappear. The closer captures this moment and generates a command to turn off the power to the electric motor. Another condition for turning off the power supply of the electric motor is the excess of the maximum set time of its continuous operation - 9 s. The glass closer diagram is shown in fig. one.

Car window closer. Schematic diagram of the glass closer

(click to enlarge)

The main node of the device is the DD2 microcontroller. The control signals are fed to the input connector X2. The closer output node consists of four transistor-relay cells. The relay contacts supply power to the electric motors of the door windows (the sunroof control channel is not shown in the diagram). With the arrival of a signal from the security alarm to lock the doors, relay K1 is activated, and through contacts K1.1, power is supplied to the power window motor of the driver's door for a period of 0,75 s, of which, during the last 0,25 s, the DD2 microcontroller measures the frequency of the variable component of the onboard voltage network from the operation of the electric motor. The alternating voltage is pre-amplified by the element DD1.1. Resistor R2 forms a feedback circuit of the element and translates its transistors into a linear section of the input characteristic. Through the inverter DD1.2, the amplified signal is fed to the input RA4 of the microcontroller DD2, configured as the input of the timer-counter pulses. If the frequency of the alternating voltage exceeds 200 Hz, i.e. the motor is running, the motor relay K1 remains on. As soon as the rotor of the electric motor stops, i.e. the glass is raised to the limit, relay K1 releases the armature, the electric motor turns off, relay K2 is activated, the next electric motor turns on - the process repeats, and so on until the windows of all doors are raised. As mentioned, each power window motor first turns on for a time of 0,75 seconds. A delay of 0,5 s before starting to measure the frequency is necessary so that the motor, after switching on, has time to reach a stable operating mode.

The microcontroller program provides that the operating time of each electric window motor will in any case not exceed 9 s. When the car is disarmed, the signal to unlock the door locks is simultaneously fed to the interruption input of the door closer through pin 2 (or 5) of connector X2. After that, the DD2 microcontroller proceeds to execute the interrupt routine, which, in turn, gives the command to stop the motor if its rotor is rotating. Then the program goes into the waiting mode for a new impulse to close the windows. In order for the operation of the power windows to be disabled in the "ACC" position of the ignition lock, the contact of the lock corresponding to this position must be connected to pin 4 of the connector X2 of the closer. Contact 1 of connector X2 is connected to the negative terminal of the "Door open" indicator lamp on the dashboard of the car. If there is no such indicator, then with four pieces of insulated wire, the output of the door switch of each door that is connected to the interior lighting lamp will have to be connected to this contact. In the gap of each piece of wire in a convenient place, it is necessary to include a separating diode (for example, KD522B) with the anode to pin 1 of the connector. In this case, the VD1 diode (see the diagram in Fig. 1) should be closed with a wire jumper. The power supply is connected to connector X1. Since the power window motors are powered through this connector, it is necessary to connect the device to the on-board network through a 20 A fuse (it is installed before connector X1). The cross section of the supply copper wires must be at least 1,5 mm2. The use of such a fuse is due to the fact that in the operating mode each of the motors consumes a significant current (up to 10 A), and the starting current surge cannot be ignored. The contacts of the XZ connector are included in the break of the wires supplying the electric motors of the corresponding power windows, according to the diagram shown in fig. 2: the movable contact of the relay is to the electric motor, and the fixed closed contact is to the button.

In the figure, the cross marks the place where the power supply circuit of the power window motor of the driver's door is broken. The letter designation of the contacts of the XZ connector indicates the interior door: PL - front left, PP - front right, ZP - rear right, ZL - rear left. If the control circuit of the car's window regulators is such that when the lift button is pressed, the negative wire of the power source is connected to the electric motor through it, then the open contact of each executive relay must be connected to the negative wire of the vehicle's on-board network. When adjusting the device on a car, you may need to select the resistor R2. With the ratings of the C1R1R2 circuit elements indicated in the diagram, the device installed on the Honda car works clearly, without false positives. To control the sunroof motor, use the RB1 output (pin 7) of the DD2 microcontroller. The RA1 output (pin 18) is configured to implement the ignition switch illumination function for 6 s after the driver's door is opened and 6 s after it is closed. The backlight lamp EL1 is connected according to the diagram in fig. 3.

Instead of a lamp and a transistor, you can install an LED that matches the color and brightness of the glow. The anode of the LED must be connected to the resistor R1, and the cathode to the common wire. If the brightness of the glow is insufficient, it can be increased by selecting a resistor. I think it would not be superfluous to install a toggle switch that allows, if necessary, to turn off the closer (turn off the power supply) when operating the machine in the cold season, when the windows are almost always closed. The ignition switch illumination function will also be disabled in this case. If it is used and needed constantly, then the installed toggle switch should not turn off the closer's power, but break the signal wire connected to pin 3 (or 6) of connector X2. The device uses a PIC16F84A-04I/P microcontroller; voltage stabilizer, you can use any five-volt, taking into account the difference in the pinout. The actuating unit uses BS-115C relays from Bestar. It is possible to replace them with TR81-12VDC or domestic automotive relays (for example, 711.3747-02) with the correction of the dimensions of the printed circuit board and the pattern of conductors. Chip K561LN2 is replaceable by CD4049. The inputs of these microcircuits are capable of operating with a voltage exceeding the supply voltage (in this case, 5 V). We will replace the 1N4734A zener diode with the KS156A, and instead of the 1N4744A, the domestic KS515A will do. Both zener diodes perform protective functions and are closed during normal operation. All parts of the glass closer are mounted on a printed circuit board made of fiberglass laminated on both sides with a thickness of 1 mm. The drawing of the board is shown in fig. four.

Car window closer. Closer printed circuit board

At those points on the board where the printed conductors of one side are connected to the conductors of the other, the leads of the parts should be soldered securely. At eight soldering points of the relay outputs on the part installation side, tubular caps should be installed, flared and pre-soldered. Capacitors C4 and C5 are soldered on the print side to the terminals of resistors R7 and R8. The board is placed in a plastic box of suitable dimensions and fixed in it with hot glue. To protect against moisture from the outside, a vinyl cover is pulled over the box. A box with a closer is installed under the driver's door trim.

Download microcontroller programs

Author: V. Surov, Gorno-Altaisk, Radio No. 4 2008; Publication: cxem.net

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