The electronic throttle valve is installed between the mass air flow sensor and the intake manifold. It regulates the air that is drawn in by the engine. The ratio of air to fuel changes depending on the opening angle of the throttle valve.

The position of the accelerator pedal and any other information from the engine control unit (ECU) are permanently synchronised. Based on all the measured data, the ECU determines the best possible position for the throttle valve. The throttle valve is actuated by a signal from the engine control unit. This electronic control is helpful for very efficient engine control.

Possible sources of faults are contamination due to deposits of dirt or soot or foreign bodies. In addition, the gears in the throttle valve are subject to signs of wear and can therefore become damaged over time. Other faults can be defects in the motor or potentiometer.

Hitachi Astemo has extensive and profound experience with electronic throttle bodies, as we have been supplying all established vehicle manufacturers for decades.

The Hitachi Astemo Aftermarket product programme currently consists of around 100 products.

With our current programme, we cover more than 50 million vehicles on the road in the EMEA region*. As part of the general expansion of our product coverage, we plan to continue to expand our programme significantly in the near future.

An important criterion for the development of an automobile is the compliance with the legal emission standards. In order to adhere to these emission standards it is, amongst other things, necessary to ascertain the exact relationship between the air mass to the fuel quantity. The ascertainment of the air mass is undertaken by the so-called “Air Flow Meters”.

It is used to measure the air mass flow in combustion engines (e.g. petrol and diesel motors) and provides the motor management or the fuel-injection system with relevant values via its electronic output signals. These values are needed by the motor management in order to exactly define the injected fuel quantity, dependent on the currently needed performance, the air pressure and the air temperature.

Assembly

The actual sensor is integrated in the flow channel of the pluggable sensor. These pluggable sensors are suitable for the installation in the air filter, as well as in so-called gauge tubes, which one can find in automobiles. An electronic measuring system transforms the sensor data into corresponding measuring data for the motor management / the fuel-injection system.

Function

The functional principle is based on an indirect measurement of the air current. A heating element is supplied with power during operation and thereby heated up. The on-rushing air now causes a cooling down of the heating element. The heat that is detracted from the heating element gives information about the on-rushing air mass. The larger the air mass, the larger the cooling down of the heating element is respectively the thereby created temperature difference.
The electronics that are integrated in the pluggable sensor analyzes this data and thereby allows for a precise ascertainment of the on-rushing air quantity.

Today our product portfolio consists of 302 air flow meters which cover a total of 10.455 vehicle types.

Shock absorbers

Shock absorbers play a crucial role in the vehicle chassis. They reduce the shocks and vibrations that occur while driving. Shock absorbers work in conjunction with the suspension springs to control and optimize the movement of the vehicle. The way shock absorbers work is based on a simple principle: they contain a piston rod that is moved up and down in a cylinder containing hydraulic fluid or gas. When the vehicle drives over a bump, the piston rod moves in the damber. The hydraulic fluid or gas is forced through the valves, creating resistance. This resistance converts the kinetic energy into heat, which is then dissipated through the shock absorbers.

By controlling the movement of the vehicle suspension, shock absorbers help to improve handling, maximise traction and increase ride comfort.

Shock absorbers can be damaged by various causes. These include:

• normal wear and tear: Like every component, shock absorbers are also subject to wear and tear over time. They can wear out as a result of daily use and driving over uneven roads.
• excessive load: If the vehicle is regularly overloaded or heavy loads are transported, shock absorbers can be overstressed and wear out prematurely.
• vehicle age: As the vehicle ages, the shock absorbers can lose performance and work less effectively.
• damage due to road damage: Driving over potholes, kerbs or other road damage can cause damage to the shock absorbers.
• malfunction of the seals: If the seals in the shock absorbers leak, this can lead to a loss of hydraulic fluid or gas and impair performance.

It is important to check the shock absorbers regularly and replace them if there are signs of wear or damage.

The Hitachi Astemo product programme currently consists of over 1,000 products. These are marketed under the Tokico brand.

An ignition coil is a component that transforms the battery’s low voltage to the thousands of volts required by the spark plugs to efficiently ignite the air / fuel mixture. Ignition coils consist of primary and secondary coils which have different numbers of copper windings on them. When the electric current of the primary coil is switched off, a high voltage is induced in the secondary coil. In the past, the high voltage was generated in one ignition coil and then passed on to the different cylinders by the ignition distributor and ignition cables. Modern engines today typically use 1 or 2 single coils per cylinder. The life cycle of an ignition coil is greatly dependent of the surrounding conditions in the engine itself. Changes in temperature and vibrations can have a great influence.

The following problems can occur when an ignition coil is damaged:

• Engine RPM will not increase or stuttering of the engine during acceleration can occur
• General stuttering of the engine
• The idle speed becomes unstable
• Problems during start of engine, even though battery and starter are functioning

Today our product portfolio consists of 505 ignition coils which cover a total of 15.696 vehicle types.

To ease the starting sequence and to secure an engine start below 0°C, glow plugs are used. Their task is to raise the temperature in the combustion chamber at the point where the diesel injection occurs.

Glow plugs have a very low resistance. In cold condition they have around 0,3Ω - 1Ω, this changes very fast with the rising temperature. This low resistance allows a high current to flow.
The task of the glow plug relay is not just to switch the current on and off.
Depending on the model year of the vehicle they are built-in and the type of used glow plugs, there are several timings to be considered. Additionally the temperature influences these timings:

• Pre-Heating Time
• Heating Time
• Post-Heating Time

The first units use internal timings for heating and only check the temperature to variegate these timings. At these units the current is switched with real relays.
Some units use 2 relays to handle the high current.

Newer units starting from around 2001, are completely controlled by the Electronic Diesel Control (EDC). Their communication is realized with a bus signal. These units are able to check if the glow plugs are defective. In these GPRs semiconductors are used instead of relays.

At the newest glow plug relays, starting from around 2007, the bus communication is realized with a LIN protocol. These have an advanced failure check mode.8

Today our product portfolio consists of 222 glow plug relays which cover a total of 16.697 vehicle types.