So-called electro-hydraulic power Electro-hydraulic power steering EHPS for short, exactly the same the booster principle with mechanical hydraulic power, hydraulic pump driven by the engine via a belt while with mechanical hydraulic power the biggest difference is no longer in use, but replaced by a power-driven electronic pump.
Advantage of the electro-hydraulic power is first reflected in the energy, electronic pump driven by the energy generator and battery output power, the power of the engine itself is no longer consumed, the electronic pump start-up and shut down all controlled by an electronic system without do the steering movements, electronic pump off, that unlike mechanical hydraulic booster pump as always linkage with the engine, to further reduce energy consumption.
Electro-hydraulic power steering system steering control unit from the storage tanks, booster, electric pump, steering gear, power steering sensors, power steering control unit and the electric pump which is a whole structure.
Secondly, the electro-hydraulic power steering system of the electronic control unit, it is possible by the vehicle speed sensor, a lateral acceleration sensor, steering angle sensor, the sensor information processing, by changing electronic pump flow in real time to change the intensity of the size of the power steering, that is, along with speed variable power-assisted function. Of course, not only the electro-hydraulic power can be achieved help with the speed variable.
This hydraulic type EPS in the conventional hydraulic power steering system based on the addition of the solenoid valve for controlling liquid flow, a speed sensor and an electronic control unit, etc., the electronic control unit according to the detected vehicle speed signal, the control solenoid valve, so that the steering power magnification continuously adjustable to meet the high and low speed when the power steering requirements. Simply put, when the low-speed large steering, electronic control unit drives the electronic hydraulic pump to output large power at a high speed, so that the driver fight direction effort; automobile traveling at high speed, the hydraulic control unit drives the electronic hydraulic pump at a lower speed operation need not affect the high-speed hit shift at the same time, saving a portion of the engine power. Is the current use of the more common types of power steering systems in the form.
Compared to the electronic power steering system, it is unique in its more on the structure of a detection of the angular velocity of the steering wheel rotation speed sensor (power steering sensor).
Electro-hydraulic power features: both from the point of view of technology, function, or economic, electro-hydraulic power are more mechanical hydraulic power advantage, however, electro-hydraulic power did not able to replace the mechanical hydraulic power, mainly due to the following aspects:
An electro-hydraulic power costs higher. Relatively mechanical-hydraulic power system, adding the electronic control system replaced the electronic pump, electro-hydraulic power higher manufacturing costs, the technology is also more complex, also will increase the difficulty and cost of maintenance.
Reliability is less than the the mechanical hydraulic power. Electro-hydraulic power will appear to the steering mechanism and the failure of the hydraulic mechanism, but also increase the possibility of failure of the electrical system, and thus less than traditional hydraulic power system reliability.
Boost efforts are limited. Although there are obvious advantages to use the electronic pump, electronic pump, however, need to be driven by the electric energy of the generator is able to provide the maximum current of the power itself of the vehicle generator and the battery are limited, so the power of the electronic pump also restricted, capable of carrying the load is limited. Therefore, using electro-hydraulic power models are mostly small and medium-sized vehicles. Electro-hydraulic power systems on some vehicles need a larger boost efforts beyond the reach of the.
4. Evolution of mechanical hydraulic power system. With the development of the technology, with the speed of the electro-hydraulic power variable function in the evolution of mechanical hydraulic power system has been able to achieve (using electromagnetic valve technology), even in the mechanical-hydraulic power steering system based on the derived can active steering gear ratio, higher reliability and load bearing the mechanical hydraulic power system is still welcomed by the manufacturers.
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