Bosch produces several automotive sensors that measure various parameters. This includes a steering wheel angle sensor that measures angles from -780 to 780 degrees using magnets and resistance changes. A yaw sensor measures vehicle rotation around the vertical axis using oscillating masses in a magnetic field to detect rotational movement. Rotational speed sensors use inductive proximity to generate an AC voltage from a rotating toothed ring to determine engine and wheel speeds. These sensors output analog or digital signals for various vehicle control systems.

1. Bosch Sensors
Steering Wheel Angle Sensor.
This sensors can measure angles from -780º to 780º, it has a multiple rotation function
and a can interface.
Function.
When the steering wheel is turned, it rotates a gearwheel which in turn drives two other
special measuring gears which incorporate magnets. AMR elements change their
resistance as a function of the direction of the magnetic field. These values are there
inputted to a microprocessor via an ADC. By combining both angles of rotation, it is
possible to calculate the total angle of rotation. The steering-wheel angle is then
outputted in the form of an absolute angle across the total steering-column rotation
range. The angle of rotation is available immediately after the ignition is switched,
meaning that it is an absolute, non-volatile sensor. The values are outputted via CAN.
Output Signal.
Analog.
Throttle-valve angular
It is a potentiometic angular-position sensor with a linear characteristic curve. It has a
sturdy construction for extreme loading and is very compact.
These sensors are used in automotive applications in order to measure the angle of
rotation of the throttle valve.
Function
The throttle-valve angular-position sensor is a potentiometric sensor with a linear
characteristic curve. It generates a voltage ratio which is proportional to the throttle
valve’s angle of rotation. The rotor is attached to the throttle-valve shaft and when the
throttle valve moves, the sensor’s special wipers move over their resistance tracks so the
throttle’s angular position is transformed into a voltage ratio.

2. Output Signal
Analog.
Yaw Sensor (Gyrometer).
It is compact, highly integrated with electronics and can withstand mechanical or electrical
interference. It measures yaw rate and acceleration vertical to the rotary axis
simultaneously. It can measure from .2 to 100 degrees per second. It is used in automotive
engineering for vehicle dynamics control (ESP) and measures the vehicle’s rotation around
its vertical axis, while measuring the acceleration at right angles to the driving direction.
The sensor can differentiate between normal cornering and vehicle skidding movements.
Function
Two oscillatory masses each have a conductor attached through which AC flows. Since
both are located in a constant magnetic field, they are each subjected to an electro-
dynamic force which causes them to oscillate. If the masses are also subjected to
rotational movement, coriolis forces are also generated. This is a measure for the yaw
rate.
Output signal
Analog.
Inductive rotational-speed sensors
They are proximity, wear-free, rotational-speed measuring sensors. It has a sturdy design,
a powerful output signal and the measurement depends on the direction of rotation. They
measure engine speeds and wheel speeds for abs systems and convert these speeds into
electric signal.
Function
The sensor is surrounded by a winding and located opposite a rotating toothed pulse ring.
The soft-iron core is connected to a permanent magnet, whose magnetic field extends
into the ferromagnetic pulse ring. A tooth concentrates the magnetic field and amplifies
the magnetic flux in the coil, whereas the magnetic flux is attenuated by a tooth space.
Changes in magnetic flux are generated at the transitions between tooth space and tooth

3. edge. These changes in magnetic flux induce an AC voltage in the coil, the frequency of
which is suitable for determining the rotational speed.
Output signal
Digital.
Rotational speed sensor:
For this application we can use a Hall effect sensor, it is wear free, Insensitive to
dirt and contamination and it also is fuel and Oil resistant. Because of their characteristics
and operating systemthey are precise and reliable. Hall effect sensors are build up by a
semiconductor Wafer a permanent magnet and some Transistors arranged all together on
a plastic plug housing. The output signal from this sensor due to its IC is a digital signal
that can bring information about the speed, direction and position of the Crankshaft by
reading the Proximity of a tooth on the trigger wheel design. Also this information will
help the ABS and TCS systems.
Acceleration sensor:
Pyroelectric sensors up to +/- 5 g
Used to register information from the vehicle acceleration which are directly related to
the crankshaft speed. It is an electro-mechanical systemthat works by a bending
piezoelectric material that generates a mechanical Tension resulting in a charge of
electricity that will be measured in a Radiometric output signal. It's pyroelectric behavior
depends on temperature.
Piezoelectric sensors up to 35 g
They are used on occupant protection systems such as the Air bags, Seat belts, seat belts
blocking systemand others. Their main function is to detect and register acceleration
changes. The operating principle is based on a piezoelectric effect generated by pressure
changes.
Surface-Type micromechanical sensors +/- 10 g to +/-50 g
They are used to measure the acceleration y 2 different axes, it works by a capacitive
measuring principle, which consists on the capacitance between 2 charged seismic masses
suspended by some wave shaped springs working as a variable capacitance capacitor.

4. Piezoelectric vibration sensor (Measurement of structure-borne noise/acceleration)
Function in a car. Are suitable for the detection of structure-borne acoustic oscillations as
can occur for example in case of irregular combustion in engines and on machines.
Design and function. A mass exerts compressive forces on a piezo-ceramic element in time
with the oscillation which generates the excitation. The forces result in charge transfer
within the ceramic and a voltage is generated between the top and bottom of the ceramic.
Output signal. Analog.
Piezoelectric vibration sensor (Signal evaluation module)
Function in a car. Evaluation of the analog signals from piezoelectric sensors.
Design and function. The analog signals are evaluated by a circuit integrated in the module.
The circuit contains a programmable amplifier, a band-pass filter, a rectifier, an integrator
and control logic circuit. A “measuring window” is set by a frequency divider which is
programmed, it generates the system clock for the analog stage and the test frequencies
depending upon the setting of the filter.
Output signal. Digital.
Micromechanical differential-pressure sensors hybrid design.
Function in a car. On internal-combustion engines, this sensor is used to measure the
differential pressure between the intake-manifold pressure of the drawn-in air and a
reference pressure which is inputted through a hose.
Design and function. It has a piezoresistive pressure-sensor element and suitable electronic
circuitry for signal amplification and temperature compensation mounted on a silicon chip.
Its measurement range goes from -100 kPa to 5 kPa. The measured pressure is applied to
the rear side of the silicon diaphragm, and a reference pressure is applied from above to
the diaphragm’s active surface.
Output signal. Analog.
Differential-pressure sensors
Function in a car. This sensor is used for measuring fuel-tank pressure.
Design and function. It is designed with a micromechanical pressure element with
diaphragm and connector fitting, also a silicon chip is integrated with piezoresistive sensor

5. element and a circuit for signal amplification together with temperature compensation. It
can measure from -2.5 kPa to 3.75 kPa. The measurement is carried out by routing the
monitored medium through the pressure connector and applying the prevailing pressure to
the piezoresistive sensor element.
Output signal. Analog.
Absolute-pressure sensor
Measures atmospheric pressure from 60 kPa to 160 kPa
Function:
This sensor comprises a temperature-compensated measuring element for determining the
barometric absolute pressure.In this monolithic integrated silicon pressure sensor, the
sensor element, and the respective evaluation circuitry with calibrated elements are all
united on a single silicon chip. The silicon chip is glued onto a hybrid substrate to facilitate
automatic SMD assembly.
Automotive application: Manifold vacuum measurement for engine management. Charge-
air-pressure measurement for charge-air pressure control, altitude-pressure-dependent
fuel injection for diesel engines.
Signal output: Analog
Piezoresistive absolute-pressure sensors in thick film technology
Measurement of pressures in gases up to 250 kPa
Function: Piezo-resistivethick-film strain gauges areprinted onto the bubble and protected
with glass against aggressive media. The strain gauges are characterized by high
measurement sensitivity as well as by linear and hysteresis-free behavior. When pressure
is applied, they convert mechanical strain into an electric signal.

6. Output: analog
Absolute-pressure sensors in micromechanical hybrid design
Measures pressures in gases up to 400 kPa
Function: This sensor is used to measure the absolute intake-manifold pressure. The
measured pressure is applied from above to the diaphragm’s active surface. A reference
vacuum is enclosed between the rear side and the glass base.
Output signal: Analog