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CAR WIPER

MECHANISM

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 The wipers combine two mechanicaltechnologies to perform their task:

A combination electric motor and worm

gear reduction provides power to thewipers. A linkage converts the rotational output of

the motor into the back-and-forth motion of

the wipers.

Introduction

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In order to generate this type of force toaccelerate the wiper blades back and forthacross the windshield quickly. a worm gear isused on the output of a small electric motor.

 The worm gear reduction can multiplythe torque of the motor by about ! times"while slowing the output speed of the electric

motor by ! times as well. The output of thegear reduction operates a linkage that movesthe wipers back and forth.

Motor and Gear Reduction

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Inside the motor#gear assembly isan electronic circuit that senses when the

wipers are in their down position. The circuitmaintains power to the wipers until they areparked at the bottom of the windshield"then cuts the power to the motor. This

circuit also parks the wipers between wipeswhen they are on their intermittent setting.

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A short cam is attached to the output shaftof the gear reduction. This cam spinsaround as the wiper motor turns. The cam isconnected to a long rod$ as the cam spins" itmoves the rod back and forth. The long rodis connected to a short rod that actuatesthe wiper blade on the driver%s side. Another

long rod transmits the force from the driver-side to the passenger-side wiper blade.

Linkage

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Wiper Blades

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Pivot Points

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Wiper Blade !pes

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Wiper Controls

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A new type of wiper system is starting to appear on carsthat actually does a good &ob of detecting the amount ofwater on the windshield and controlling the wipers.

'ne such system is made by T() Inc system.

 T() Inc. uses optical sensors to detect the moisture. The sensor is mounted in contact with the inside of thewindshield" near the rearview mirror.

 The sensor pro&ects infrared light into the windshield ata *degree angle. If the glass is dry" most of this light is

re+ected back into the sensor by the front of thewindshield. If water droplets are on the glass" theyre+ect the light in di,erent directions the wetter theglass" the less light makes it back into the sensor.

Wiper Advance"ents

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 The electronics and software in the sensorturn on the wipers when the amount of lightre+ected onto the sensor decreases to apreset level. The software sets the speed ofthe wipers based on how fast the moisturebuilds up between wipes. It can operate thewipers at any speed. The system ad&usts the

speed as often as necessary to match withthe rate of moisture accumulation.