Electric power steering

The EUR consists of the following main elements:

• Torsion shaft steering shaft
• Electric motor
• Electronic control unit (ECU)
• Torque sensor (non-contact)
• Rotor position sensor

The principle of operation of the electric power steering:

The electric amplifier is installed on the steering shaft of the car, the parts of which are interconnected by a torsion shaft , with a torque sensor installed. When the steering wheel rotates, the torsion shaft is twisted, recorded by the torque sensor.

Based on the data received from the torque sensor, as well as data from the speed and crankshaft speed sensors, the electronic control unit calculates the necessary compensation force and sends a command to the amplifier motor.

1st option:
The electric motor and gearbox are located on the steering column, the full moment exits already from the steering wheel shaft.

2nd option:
The gearbox is mounted on the rail itself, which allows not to overload the steering shaft and its joints.

The advantages of the EUR in comparison with the hydraulic power steering (GUR) are:

• Simplicity of design and maintenance. Power steering, in contrast to the EUR, requires constant monitoring of the liquid level, pump maintenance.
• The compactness of the mechanism. The EUR is mounted on the steering shaft and does not require additional space under the hood of the car.
• Profitability. The electric motor of the EUR is switched on only when the steering wheel is rotated, while the power steering pump works continuously, creating an additional load on the engine, thereby increasing fuel consumption.
• Easy setup. Only by changing the ECU program it is possible to achieve different operating modes under various circumstances, such as a decrease in the compensation force with increasing vehicle speed. In the case of power steering, this will require additional active elements in the design.

The disadvantages of the EUR in comparison with the power steering:

• Small (less) power due to the power of the generator. The EUR is installed only on light vehicles, insufficient power will not allow it to be used on heavy SUVs or trucks, without fear of the load on the on-board network of the car and the amplifier motor. At the same time, the ESD consumes a relatively high current from the onboard network, creating a significant load: for example, the ESD of the Suzuki Wagon R shown above can consume up to 30 Amps from the onboard network, which is 40% of the generator power (the specified current is the maximum standing motionless, with less driving, and after 60 km / h the EUR will be turned off altogether, in order to avoid excessive controllability).

• In heavy operation, for example, during prolonged movement on a muddy dirt road, the electric motor of the EUR will overheat. To prevent its failure, the control unit begins to limit the maximum current, respectively, the steering wheel is "heavier", and ultimately turns off completely. To restore normal operation, it is necessary to stop the car for a while, in order to cool the motor windings, after which operation will be restored.

The disadvantages inherent in both the EUR and the power steering, in comparison with the steering without an amplifier:

• Occurrence of danger when driving in the event of a failure of both types of power steering (the driver’s response may not be sufficient to detect failure of the power steering system in a timely manner if this occurs when the vehicle turns).

• Power steering
• Power steering
  • Power Steering
  • Power steering

• video explaining the principle of electric power steering