Under normal circumstances, only a small part of the energy required for the steering of a car using a power steering system is the physical energy provided by the driver, and most of it is the hydraulic energy provided by the oil pump (or air compressor) driven by the engine (or motor) (or barometric energy).
It is used to convert part of the mechanical energy output by the engine (or motor) into pressure energy, and under the control of the driver, apply hydraulic or pneumatic forces in different directions to the steering gear or a transmission member in the steering gear to help the driver A series of parts with insufficient force are collectively called power steering gear. The types and working principles of power steering are introduced below.
(1) Type of power steering gear
According to the difference of energy transfer medium, there are two types of power steering gears: pneumatic type and hydraulic type. Pneumatic power steering is not suitable for trucks with extra-large loads, because the working pressure of the pneumatic system is low (generally not higher than 0.7MPa), and when used on heavy-duty vehicles, the size of its components will be too large. The working pressure of the hydraulic power steering gear can be as high as 10MPa or more, so the size of its components is very small. The hydraulic system works without noise, has a short working lag time, and can absorb shocks from uneven roads. Therefore, the hydraulic power steering gear has been widely used in various levels of automobiles.
According to the different arrangement and connection relationship of the mechanical steering gear, steering power cylinder and steering control valve in the steering device, the hydraulic power steering device is divided into integral type (mechanical steering gear, steering power cylinder and steering control valve) Design as one), combined type (design the mechanical steering gear and steering control valve together, and the steering power cylinder is independent) and separate type (the mechanical steering gear is independent, and design the steering control valve and steering power cylinder as a whole) Structure type.