|
|
We all know that with power windows you push the button up or down, and the windows move. But how does this really work?
It all begins with the car battery that sends the power to the power distribution box, from there the power is directed to the ignition; so that when you turn on the vehicle the windows will be in operation. From the ignition a wire runs to the fuse box before leading on to the window switch, this is essential in the case of a fault. The fuse will burn out therefore preventing any major costly repairs to larger components.
The switch works by closing and opening two different sets of wire circuits, and then the wires are redirected to the power windows motor. When you push the switch one way, one set closes and another opens. If you push the switch the other way the opposite sets open and close. This is necessary in determining which way the motor should run.
The majority of power windows work in the same way by having an automatic down feature on the driver side window; if you hold the switch down the window will lower until you release the switch, but if you just tap the switch, the window will open fully. Most power windows however, don’t have an automatic up feature due to the danger of something or someone becoming trapped. There is normally a circuit which determines the speed of the motor, if the motor slows down before the window is closed, it will stop and reverse the opposite way therefore opening the window again.
The power window motor is a small motor that has an attached worm gear. This worm gear is a length of metal with a spiral on one end, similar to that of a screw.
The worm is attached to a gear; this circular gear has teeth around the outside. We can all picture this as a form of cog. As the worm turns it moves the gear by linking the teeth inside the spiral; the gear is then linked to several spur gears. Spur gears are used to create gear reductions in machines with motors.
The worm is fixed at a specific angle to the gear, which allows the worm to turn the gear, but prevents the gear from turning the worm. The motion of the worm and gears create a gear reduction which gives enough force to turn or rotate things, this is called torque.
There are supporting bars below each electric window and attached to each bar is an arm. This arm slides along the bars as the window rises and falls. The other end of the arm has a plate with teeth that slot into the teeth of the gears; as the gears turn so does the arm and in turn raises or lowers the window glass. On the opposite side of the bars is a counter arm that counteracts the weight of the window, so if the main arm is raised on the right side of the window the counter arm will be raised on the left, ensuring that the glass rises and falls evenly and level.
The mechanisms are very similar in manual windows as that of power windows, but instead of the motor turning the gears the crank handle does the work.