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Classification Of Automobile Suspension System
Mar 08, 2018

According to the different control forms, it is divided into passive suspension and active suspension.

It can be divided into independent suspension and non independent suspension according to the different automobile guiding mechanism.

The structural features of the non-independent suspension are that the two wheels are connected by an integral axle, and the wheel together with the axle is suspended by the elastic suspension under the frame or the body. Non-independent suspension has the advantages of simple structure, low cost, high strength, easy maintenance and small change of front wheel alignment during driving, but is largely discontinued in modern cars because of its poor comfort and handling stability Mostly used on trucks and buses.

The independent suspension is that the wheels on each side are individually suspended on the frame or under the body through an elastic suspension. The advantages are: light weight, reducing the impact on the body, and improve the ground adhesion of the wheels; can be used less soft soft spring spring to improve the car's comfort; can make the engine position decreases, the car's center of gravity has been reduced, and thus Improve the driving stability of the car; the left and right wheels beat independently, and they are irrelevant to each other, which can reduce the body's tilt and vibration. However, the independent suspension has the disadvantages of complicated structure, high cost and inconvenient maintenance. Most modern cars use independent suspensions. According to their different structural forms, independent suspensions can be divided into horizontal arms, longitudinal arms, multi-links, candlesticks, and McPherson-type suspensions.

Arm suspension is the wheel in the car horizontal plane swing independent suspension, according to the number of cross arm is divided into double wishbone and single wishbone suspension.

Single-wishbone has the advantages of simple structure, high roll center, strong anti-roll ability. However, with the increase of the speed of modern vehicles, the high center of roll will cause the wheelset to change greatly when the wheel beats, the tire wear will be aggravated, and the vertical force of the left and right wheels will shift too much when the cornering turns, resulting in the increase of rear wheel camber and decrease The rear wheel side stiffness, resulting in high-speed drift tail serious conditions. Single wishbone independent suspensions are mostly used on rear suspensions, but they are not widely used because they cannot meet the requirements of high speed driving.

The double wishbone independent suspension is divided into equal length double wishbone and unequal length double wishbone suspension according to whether the upper and lower cross arms are of equal length. The double wishbone suspension of equal length can maintain the inclination of the kingpin while the wheel is beating up and down, but the wheelbase changes greatly (similar to the single-arm type), resulting in serious tire wear, and it has been rarely used. For unequal length double wishbone suspension, as long as the appropriate choice, optimize the length of the upper and lower arm, and through a reasonable arrangement, you can make the wheelbase and front wheel positioning parameters are within the acceptable limits of change, to ensure that the car With good driving stability. Unequal length double wishbone suspension has been widely used in the front and rear suspension car, part of the sports car and the rear of the car also uses this suspension structure.

The multi-link suspension is a suspension that is composed of (3 - 5) rods combined to control the position of the wheels. The multi-link type can make the wheels oscillate around an axis that forms a two-degree angle with the longitudinal axis of the car, which is a horizontal arm type and a longitudinal arm type of compromise, and appropriately selects the angle formed by the axis of the swing arm and the longitudinal axis of the automobile. The advantages of the cross arm type and the long arm type suspension can be obtained to varying degrees, and can meet different performance requirements. The main advantage of the multi-link suspension is that when the wheel beats the wheelbase and toe-in change is very small, and the braking state can be steered smoothly according to the driver's intention regardless of whether the car is driving or not. The disadvantage is that the car Shaft swinging at high speed.

Trailing arm independent suspension refers to the suspension structure of the wheel swinging in the longitudinal plane of the car, and is divided into two types: single trailing arm and double trailing arm. Single-trailing arm suspension when the wheel up and down the caster will make the kingpin greater change, so a single trailing arm suspension is not used in the steering wheel. The two swing arms of the double-longitudinal suspension are generally of equal length and form a parallel four-bar structure so that when the wheels run up and down, the caster angle remains constant. Double vertical arm suspension used in the steering wheel.

The structural feature of the candle suspension is that the wheel moves up and down along the king pin axis that is rigidly fixed to the frame. The advantages of the candle suspension are: when the suspension is deformed, the orientation angle of the kingpin will not change, only the wheelbase and the wheelbase slightly change, therefore, it is particularly beneficial to the steering stability and the driving stability of the vehicle. However, the candle suspension has a major drawback: that is, the lateral force when the vehicle is traveling is entirely absorbed by the kingpin sleeved on the kingpin sleeve, so that the friction resistance between the sleeve and the kingpin is increased, and the wear is also serious. The candle suspension is now not used much.

The McPherson Suspension wheel is also a suspension that slides along the kingpin, but unlike the candle suspension, its kingpin is swingable, and the MacPherson suspension is swingarm and candlestick. Suspension combination. Compared with the double wishbone suspension, the McPherson suspension has the advantages of compact structure, small front wheel alignment parameter variation when the wheel is beating, good steering stability, and due to the cancellation of the upper cross arm, The arrangement of the engine and steering system brings convenience; the lateral force on its struts is greatly improved compared to the candle suspension. MacPherson suspensions are used in the front suspension of small and medium sized cars. The front suspensions of Porsche 911, domestic Audi, Santana, Xiali, and Fukang are MacPherson independent suspensions. Although the MacPherson suspension is not the suspension structure with the highest technical content, it is still a durable, independent suspension with strong road adaptability.

Active suspension is developed over the past decade, a new type of computer-controlled suspension. It brings together the mechanics and electronics of the technical knowledge, is a more complex high-tech devices. For example, the French Citroen Sandy Ya equipped with active suspension, the center of the car suspension system is a microcomputer, the suspension of the five sensors were sent to the microcomputer speed, front wheel brake pressure, pedaling the accelerator pedal speed, Body vertical amplitude and frequency, steering wheel angle and steering speed and other data. The computer continuously receives these data and compares it with the preset thresholds to select the appropriate suspension state. At the same time, the microcomputer independently controls the actuators on each wheel and generates twitches by controlling the change of the oil pressure in the shock absorber so as to generate the required suspension motion at any time and on any wheel. Therefore, the Santiya sedan has a variety of driving mode options, as long as the driver drove the deputy instrument panel in the "normal" or "exercise" button, the car will automatically set the best suspension, in order to maximize Good comfort.

Active suspension has the function of controlling body movement. When the car brake or turning inertia caused by spring deformation, the active suspension will produce a force against inertia to reduce the body position changes. For example, the German Mercedes-Benz 2000 Cl sports car, when the vehicle turns the suspension sensor will immediately detect the body tilt and lateral acceleration. Based on the information from the sensor, the computer compares it with the preset critical value and immediately determines at what position the load is added to the suspension so that the body tilt is minimized.