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OtherSensorTypes / WheelSpeed

Wheel Speed Sensor

The "hall effect" wheel speed sensor is highly robust and designed specifically for high reliability automotive applications. It does not require a magnet to trigger it, just a moving metal "target", for example a bolt on the back of the brake disk. For direct connection to the Data Logger Units a "pull up resistor" is required. If the sensor is ordered with a cable, this resistor is already included and will be ready for immediate use with the Data Logger Units.

The sensor will function from a 4.5 to 24 VDC power supply. Output is digital, current-sinking (open collector). Reverse polarity protection is standard. If power is inadvertently wired backwards, the sensor will not be damaged. Built-in protection against pulsed transients to =60V, -40V is also included.

Optimum sensor performance is dependent on the following variables which must be considered in combination:

• Target material, geometry and speed
• Sensor?target gap
• Ambient temperature
• Magnetic material in close proximity

Typical applications include:

Automotive and Heavy Duty Vehicle:

• Camshaft and crankshaft speed/position
• Transmission speed
• Tachometers
• Anti-skid/traction control

Industrial:

• Sprocket speed
• Chain link conveyor speed and distance
• Stop motion detector
• High speed low cost proximity
• Tachometers, counters

Key features are:

• Senses ferrous metal targets.
• Digital current sinking output (open collector)
• Better signal to noise ratio than variable reluctance sensors.
• Sensor electronically self adjusts to slight variations in run-out and variations in temperature.
• Fast operating speed – over 100 kHz
• EMI resistant
• Reverse polarity protection and transient protection (integrated into Hall I.C.)
• Wide continuous operating temperature range.

Installation

The sensor comes with 3 wires, the red wire should be connected to the 5v output from the Data Logger Units, the black wire should go to the ground connection and the white wire should go to one of the frequency inputs.

Mounting Dimensions

Target guidelines.

The Target Guidelines table provides basic parameters when an application is not restricted to a specific target.

Any target wheel that exceeds the following minimum specifications can be sensed over the entire temperature range of -40^o to 150^oC with any sensing gap up to .080 in. (2,0mm). This data is based on a 4 in (102mm) diameter wheel, rotating 10 to 3600 rpm.

Reference Target Dimensions

Sensor Output (with pull-up resister added to output circuit)

Reference Target/Conditions

Characteristics will vary due to target size, geometry, location and material. Sensor specifications were derived using a cold-rolled steel reference target. See the table, below for the reference target configuration and evaluation conditions:

Target

Test Conditions

Connecting the sensor to a data logger DL1/DL2/DASH2

If the sensor has been supplied by Race Technology with a cable attached then wires from the sensors are:

• Red - Connect to the +5v reference output from the DL1/DL2/DASH2
• Back - Connect to ground (0v) on the DL1/DL2/DASH2
• White - Signal output from the sensor, this can be connected to any of the wheel speed, frequency or low level RPM inputs on the DL1/DL2/DASH2

If the sensor has been supplied without any cable, then the user will have to add in a pull up resistor - if the sensor has been supplied with cable then this resistor is already "built in" as part of the cabling assembly. In the case that the sensor has been supplied without cabling then it has to be connected up as follows: