speed sensor.pptx

speed sensor pracnetastion

1. SPEED SENSOR

2. CONTENTS: INTRODUCTION SPEED SENSOR CONSTRUCTION WORKING OF SPEED SENSOR TYPES OF SPEED SENSOR APPLICATIONS ADVANTAGES DISADVANTAGES

3. INTRODUCTION: The speed sensor, an essential component for the operation of several on-board systems, allows the magnetic rotation speed to be measured in order to provide a voltage corresponding to the rotation speed . It is widely used in the aeronautics, automotive and precision engineering sectors.

4. SPEED SENSOR CONSTRUCTION: The most common wheel speed sensor system consists of a ferromagnetic toothed reluctor ring (tone wheel) and a sensor (which can be passive or active). The tone wheel is typically made of steel and may be an open-air design, or sealed. The number of teeth is chosen as a trade-off between low-speed sensing/accuracy and high-speed sensing/cost. Greater numbers of teeth will require more machining operations and produce a higher frequency output signal which may not be as easily interpreted at the receiving end, but give a better resolution and higher signal update rate. In more advanced systems, the teeth can be asymmetrically shaped to allow the sensor to distinguish between forward and reverse rotation of the wheel.

5. A passive sensor typically consists of a ferromagnetic rod which is oriented to project radially from the tone wheel with a permanent magnet at the opposite end. The rod is wound with fine wire which experiences an induced alternating voltage as the tone wheel rotates, as the teeth interfere with the magnetic field. Passive sensors output a sinusoidal signal which grows in magnitude and frequency with wheel speed. A variation of the passive sensor does not have a magnet backing it, but rather a tone wheel which consists of alternating magnetic poles produce the alternating voltage. The output of this sensor tends to resemble a square wave , rather than a sinusoid, but still increases in magnitude as wheels speed increases.

6. WORKING OF SPEED SENSOR : How does the speed sensor work? The vehicle speed sensor measures the rotational speed of the gears in your transmission system . Then, it converts this measurement into an analog signal or a low voltage square wave signal and relays it to electronic control units (ECUs) inside your car

7. TYPES OF SPEED SENSOR: Magnetic speed sensors. O ptical speed sensors. H all effect speed sensors. G ear tooth sensor. T ransmission speed sensors. W heel speed sensors. ABS wheel speed sensors. A ngular speed sensors

8. APPLICATIONS: The speed sensor, an essential component for the operation of several on-board systems, allows the magnetic rotation speed to be measured in order to provide a voltage corresponding to the rotation speed. It is widely used in the aeronautics, automotive and precision engineering sectors .

9. ADVANTAGES: Variable reluctance sensors are passive sensors as they don’t require external power supply As the wire and magnets used are pretty inexpensive, these sensors are low cost sensors They are light weight, robust and can work in harsh(high temperature and high vibration) environments

10. DISADVANTAGES: Target material must be ferrous only. As the magnitude of the induced voltage in these sensors is proportional to target speed, it becomes difficult to design circuitry appropriate for very low speed signals. Thus Variable Reluctance sensors have a definite lower limit on the speed of the target. Though sensors themselves are cheap, the cost advantage is offset by the additional electronic circuitry required to process the low amplitude induced voltages.

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