Application and market of precision spring:
Precision springs are used in defense, marine, aerospace, electronics, machinery, electrical, clocks and other fields.
Macpherson suspension (macphersan) is now a very common form of independent suspension, mostly used in the front wheels of vehicles. Simply put, the main structure of the Macpherson suspension is a torsion spring plus a shock absorber and Composed of A-shaped lower swing arm, the shock absorber can avoid the forward, backward, left and right deviation of the coil spring of the precision spring when it is stressed, and restrict the spring to only vibrate up and down, and can pass the shock absorber The stroke, damping, and coil springs of different hardness are used to adjust the suspension performance. The biggest feature of the MacPherson suspension is that it is relatively small, which is conducive to the layout of the relatively compact engine compartment. However, it is precisely because of the simple structure that the lateral direction Can not provide sufficient support, so the steering roll and brake nodding phenomenon is more obvious. Here is a detailed introduction to the structure and performance of the MacPherson suspension.
The history of MacPherson suspension:
The MacPherson suspension was born in response to the appearance of the front-engine front-wheel drive (ff) model. The ff model not only requires the engine to be placed horizontally, but also adds a gearbox, differential, drive mechanism, and steering gear. The front suspension space had to be compressed and significantly deleted, so engineers designed a space-saving and low-cost MacPherson suspension to meet the needs of the car.
Macphersan is the name of the inventor of this suspension system. He is a native of Illinois, USA, born in 1891. After graduating from university, he worked in aero engines in Europe for many years and joined General Motors in 1924. Center. In the 1930s, GM’s Chevrolet wanted to design a real small car, and the chief designer was McPherson. He was very interested in designing small cars, and the goal was to control the quality of this four-seater car to less than 0.9 tons. The wheelbase is controlled within 2.74 meters, and the key to the design is suspension. McPherson changed the prevailing front suspension method of leaf springs and torsion bar springs, creatively combining shock absorbers and coil springs, and installed them on the front axle. Above. Practice has proved that this type of suspension has a simple structure, a small footprint, and good maneuverability. Later, McPherson jumped to Ford. In 1950, Ford’s British subsidiary produced two cars, which were the first in the world. A commercial vehicle using MacPherson suspension.
The advantages and disadvantages of MacPherson suspension:
As can be seen from the above structural diagram, the structure of the Macpherson suspension is actually very simple, and the biggest advantage of this simplicity is that its weight is very light and its volume is small. For many front-engine front-wheel drive vehicles In other words, most of the space in the front part of the car is used to arrange the horizontal engine and gearbox, leaving not much space for the suspension, so the advantages of the small size and light weight of the MacPherson suspension will be very obvious.
The simple structure is also the biggest weakness of the MacPherson suspension. Compared with the double wishbone and multi-link suspension, because the shock absorber and the precision spring coil spring support and buffer the vehicle The force of the direction does not provide enough support. This makes the vehicle body has a more obvious roll when turning, and there is a more obvious nod when braking. Many small cars with MacPherson suspension are in order to control costs , It can only keep such defects. Although the roll of the vehicle can be reduced by adding anti-roll bars, it cannot cure this situation. However, on high-performance models such as BMW M3 and Porsche 911, by adjusting elastic elements and With the addition of tie rods and other adjustments, the MacPherson suspension can also become very powerful, but this also deviates from the characteristics of the MacPherson suspension of small size, light weight and low cost.
MacPherson suspension structure:
The MacPherson suspension is composed of a precision spring coil spring, a shock absorber, and an A-shaped lower arm. Most models will also add a stabilizer bar. The physical structure of the MacPherson independent suspension is a strut type shock absorber. It doubles as a king pin, withstands the up and down prestress from the body shake and ground impact, and the steering knuckle (also called the wheel, because the steering knuckle acts on the wheel) rotates along the king pin; in addition, the king pin can swing, which is characterized by The kingpin position and the front wheel positioning angle change with the up and down of the wheels, and the front wheel positioning changes little, which has good driving stability.
In the Macpherson-style independent suspension, in addition to the shock absorption effect, the strut-type shock absorber also has the role of supporting the body, so its structure must be compact and rigid enough, and it must be able to Shock absorption, and the spring and the shock absorber together constitute a sliding column that can move up and down. There is also a key component-the A-shaped lower arm, which is used to provide lateral support for the wheels and can withstand The prestress in the front and rear directions. During the movement of the vehicle, the impact force of the wheels in all directions must be borne by the two components of the strut shock absorber and the A-shaped lower arm.