Articles three common steering assist system - mechanical hydraulic power

Friend to its early automobile steering is no booster device, thanks to the driver's physical as turning the power source, in fact, we are now also occasionally to see there is no power steering device models, this car is open heavy steering wheel impressed, driving safety and other considerations, but also in order to reduce the pilot workload, people invented the power steering system.
The power steering is to assist the driver in a motor vehicle reorientation mitigate the force strength of the steering wheel for the driver, of course, the power steering on driving safety, economy certain role. Car power steering system configuration and current information can be found, can be roughly divided into three categories, the first mechanical hydraulic steering system; electro-hydraulic power steering system; class III electric power steering systems.
The mechanical hydraulic power steering system
Provide hydraulic power steering hydraulic pump by the engine through a belt drive, which means that only the engine running, the steering pump to be able to operate, which is why the engine stall disappearance of the steering wheel booster. In the steering unit, can be rotated with the steering column has a mechanical valve, when the steering wheel is not turning left, the piston on both sides of the chamber pressure, a consistent state of equilibrium. When the steering wheel is rotated, the mechanical valve connected on the steering column will be the corresponding open or closed, fluid from the side through the hydraulic cylinder is no longer directly under reflux to the oil tank, the other side of fluid to continue to inject the hydraulic cylinder, the piston sides of a pressure difference is generated, it will under the role of the hydraulically driven, thereby generating auxiliary efforts to promote the steering rod, so that the wheel steering, so that we turn the steering wheel, the force required to be greatly reduced.
Hydraulic power steering system has another advantage, is to enhance the comfort and security, the wheel pounding and encounter potholes cause tire non-autonomous steering, hydraulic piston can be a good buffer and absorb shock that is transmitted to the vibration on the steering wheel greatly reduced. This structure also enhance the safety of vehicles such as the use of traditional rack-and-pinion mechanism in the steering tires encounter potholes suddenly change direction, the rack gear steering wheel reversal, a "hatchet man" will lead, it is easy driver's hand is hurt, there will not be such a problem in the hydraulic power vehicles.

Mechanical-hydraulic power steering system is generally by a hydraulic pump, tubing, pressure and flow control valve, V-drive belt, storage tanks and other components constitute.

Mechanical-hydraulic power type: according to the way of fluid flow within the system can be divided into different atmospheric pressure hydraulic power and the constant flow hydraulic power. Atmospheric pressure hydraulic power system characteristics regardless of the steering wheel is in the middle position or steering position, the steering wheel to remain stationary or in rotation, oil always keep the pressure in the system piping; normally flow hydraulic steering booster system steering pump always work, but when the hydraulic power system does not work, the oil pump is in the idle state, the load of the pipeline than atmospheric, most hydraulic power steering systems are often streamed. Can see, steering pumps are essential components Either way, it can be input the engine mechanical energy into fluid pressure.

Mechanical hydraulic power features: the entire system are the mechanical structure, mechanical hydraulic pump driven by a belt on the steering column hydraulic mechanical valve body, no electronic system, the technology is mature and stable, high reliability, applicable to a wide range ofeven if the vehicle's hydraulic system failure, loss of help, was able to rely on traditional rack-and-pinion mechanism for steering. The disadvantage is that the more complex structure, space, higher manufacturing costs, but also makes the difficulty and cost of maintenance are high. And hydraulic pump driven by the engine belt, regardless of the car turned to whether the system should work, it will consume part of the engine power, affect fuel economy and vehicle dynamics, especially for the power itself is relatively weak small row the amount of models more obvious. Also, because the pressure of the hydraulic pump is also relatively easy to damage the power steering system, the service life is affected. In addition, the purely mechanical-hydraulic power system booster efforts can not be adjusted, it is difficult to take into account the different needs of the low-speed and high-speed driving on the pointing accuracy. May wish to recall: On this car, especially when low-speed turn, feel the direction of the sink, and the engine is relatively effortless.