Mcphersonindependent suspension is an important part of the safety structure of the car. For a long time, the driving control and comfort of the car are closely related to the suspension system in the chassis structure, and the simplicity and complexity of the suspension structure also directly determines the cost of automobile manufacturing. the level of. Mcphersonindependent suspension is one of many suspension systems, which has won a wide range of market applications due to its simple structure, low cost and acceptable comfort.
Development history:
In the human body, bones are often connected by soft tissue, which acts as a buffer to protect the bones and insulates excess vibration from traveling to the brain and damaging brain cells. In the composition structure of the car, the role of the suspension system is just the same as the soft tissue in the human body structure. The suspension system is the whole support system composed of the elastic components, shock absorber and force transmission devices between the body and the tire. These three components are responsible for buffering, damping and force transmission respectively. The specific responsibility of the suspension system is to support the car body, filter out the unnecessary shaking of the road, and provide a smooth and comfortable riding environment for drivers and passengers.
So far, the suspension system has formed independent, semi-independent and non-independent three types. In modern cars, most use independent suspension, according to different structural forms, independent suspension can be divided into transverse arm type, longitudinal arm type, multi-link type, candle type and McPherson type. And in many kinds of independent suspension, McPherson type and simple structure, low cost, comfort is the most widely used. The McPherson independent suspension has been in use since its invention, but its structure has evolved into a complex system that now includes transverse stabilizer bars and even sub-frames. The reason why this suspension can be widely used is that its structure is very compact, does not take up much space, and manufacturing costs are not high. From tiny transport at Otto familiar to the pursuit of speed and manipulation of the limit of the BMW M3, Porsche 911, without exception, are in the front overhang adopted the simple structure, good extensibility suspension system, just in order to adapt to different market positioning and product demands, set-up in spring damping coefficient and structure match on each different.
The Mcphersonindependent suspension wheel is also along the kingpin slide suspension, but not exactly the same as the candle-type suspension, its kingpin can swing, Mcphersonindependent suspension is a combination of swing arm and candle-type suspension. Compared with the double transverse arm suspension, the advantages of Mcphersonindependent suspension are: compact structure, small changes in front wheel positioning parameters when the wheel beats, good handling stability, coupled with the cancellation of the upper transverse arm, bring convenience to the engine and steering system layout; Compared with candle-type suspension, the lateral force of its sliding column has been greatly improved. Mcphersonindependent suspension is applied to the front suspension of small and medium-sized cars. The front suspension of Porsche 911, Domestic Audi, Santana, Xiali, Fukang and other cars are Mcphersonindependent suspension. While the Mcphersonindependent suspension is not the most technical suspension construction, it is still a durable independent suspension with strong road adaptability .
There is another record about Mcphersonindependent suspension in the history of automobile industry. McPherson was born in Illinois in 1891. After graduating from University, he worked in in Europe for many years and joined the engineering center of General Motors in 1924. In the 1930s, GM Chevrolet division wanted to design a real small car, and the chief designer was McPherson. He is very interested in designing small cars. His goal is to control the quality of this four seat car within 0.9 tons and the wheelbase within 2.74 meters. The key to the design is the suspension. McPherson changed the prevailing front suspension mode of leaf spring and torsion bar spring at that time, and creatively combined the shock absorber and coil spring on the front axle. Practice has proved that this suspension form has the advantages of simple structure, small occupied space and good maneuverability. Later, McPherson changed jobs to Ford. In 1950, the two cars produced by Ford’s subsidiary in the UK were the first commercial cars in the world to use Mcphersonindependent suspension. Mcphersonindependent suspension
Because of its simple structure and superior performance, it is praised as a classic design by experts.
Mcphersonindependent suspension is one of the most widely used car front suspension in the world. Mcphersonindependent suspension is composed of coil spring, shock absorber and triangular lower swing arm. Most models will also add lateral stabilizer bar. The main structure is simple, that is, the coil spring is sleeved on the shock absorber. The shock absorber can avoid the forward, rear, left and right offset of the coil spring when it is stressed, limit the spring to vibrate up and down, and use the stroke length and tightness of the shock absorber to set the soft, hard and performance of the suspension. Mcphersonindependent suspension has simple structure, so it is light and fast in response. In addition, under the geometric structure of a lower rocker arm and strut, it can automatically adjust the camber angle of the wheel, so that it can adapt to the road surface when cornering and maximize the grounding area of the tire. Although the Mcphersonindependent suspension is not a suspension structure with high technical content, the performance of the Mcphersonindependent suspension in driving comfort is still satisfactory, but due to its straight cylinder structure, it lacks blocking force to the impact in the left and right directions, The anti braking effect is poor, the suspension stiffness is weak, the stability is poor, and the turning roll is obvious.
Aufbau principle:
The figure shows the McPherson front independent suspension of Jet-ta. The cylindrical shock absorb 7 is a sliding column, the inner end of the yaw arm 12 is connected with the vehicle body through the hinge 10, and its outer end is connected with the steering knuckle 8 through the ball hinge 15. The upper end of the shock absorb is connected with the vehicle body through the vibration isolation block assembly 2 with bearing (which can be regarded as the upper hinge point of the shock absorb), and the lower end of the shock absorb is connected with the steering knuckle. Most of the lateral force on the wheel is borne by the yaw arm through the steering knuckle, and the rest is borne by the shock absorb piston and piston rod. Therefore, compared with candle suspension, this structure reduces sliding friction and wear to a certain extent.
The connecting line between the center of the upper hinge of the cylindrical shock absorb and the center of the ball hinge at the outer end of the yaw arm is the main pin axis. This structure is also a kingpin free structure. When the wheel jumps up and down, the angle of the kingpin axis changes because the lower fulcrum of the shock absorb swings with the yaw arm. This indicates that the wheel moves along the oscillating kingpin axis. Therefore, when the suspension is deformed, the positioning angle and track width of the main pin will change. However, if the arrangement of the linkage is properly adjusted, these positioning parameters of the wheel can change very little.
Advantages and disadvantages：
The main advantages :
Mcphersonindependent suspension has good responsiveness and handling, and simple structure, small footprint, low cost, light weight, suitable for the placement of large engines and small car body.
Other advantages
Other advantages of Mcphersonindependent suspension are:
A. Due to the large effective distance C, the force acting on the car body connection points E and D is small.
B. There is only a small distance D between G and N;
C. Spring stroke is large
D. Three supports are omitted
E. Easy to construct front floor shape
Disadvantages :
When driving on uneven roads, the wheel is easy to turn automatically, so the driver must keep the direction of the steering wheel hard, when subjected to violent impact, the slide column is easy to cause bending, thus affecting the steering performance. Poor stability, roll resistance and braking nodding ability is weak, adding the stabilizer bar can alleviate the problem but cannot fundamentally solve the problem, durability is not high, shock absorb is prone to oil leakage and needs to be replaced regularly.
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Post time: Apr-22-2022