Car suspension system refers to the entire support system composed of springs and shock absorbers between the body and tires. The function of the suspension system is to support the body and improve the riding experience. Different suspension settings will make the driver feel different.
According to 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 different car steering mechanisms.
Dependent suspension The structure of a non-independent suspension is that the wheels on both sides are connected by an integrated axle, and the wheels and the axle are suspended under the frame or the body through an elastic suspension. Non-independent suspensions have the advantages of simple structure, low cost, high strength, easy maintenance, and small changes in front wheel positioning during driving, but due to their poor comfort and handling stability, they are basically no longer used in modern cars. , Mostly used in trucks and buses.
Independent suspension Independent suspension means that the wheels on each side are individually suspended under the frame or body by elastic suspension. Its advantages are: light weight, reducing the impact of the vehicle body and improving the ground adhesion of the wheel; softer springs with less stiffness can be used to improve the comfort of the car; the position of the engine can be lowered, and the center of gravity of the car can also be reduced, thereby Improve the driving stability of the car; the left and right wheels jump separately and are irrelevant, which can reduce the tilt and vibration of the car body. 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 transverse arm, trailing arm, multi-link, candle, and Macpherson suspensions.
Wishbone suspension Wishbone suspension refers to an independent suspension with wheels swinging in the transverse plane of the car. It is divided into double-wishbone and single-wishbone suspensions according to the number of arms. The single wishbone type has the advantages of simple structure, high roll center, and strong anti-roll capability. However, with the increase of the speed of modern cars, too high the center of roll will cause the wheel track to change greatly when the wheel is bounced, and the tire wear will increase, and the vertical force of the left and right wheels will be excessively shifted during sharp turns, resulting in increased rear wheel camber and reduced The rear wheel’s sideways stiffness is caused, which results in severe working conditions of high-speed tail-flick. The single wishbone independent suspension is mostly used in the rear suspension, but because it cannot meet the requirements of high-speed driving, it is not widely used. Double-wishbone independent suspension is divided into two kinds of suspensions of equal-length double-wishbone and unequal-length double-wishbone according to whether the upper and lower cross-arms are equal in length. Equal-length double-wishbone suspension can keep the kingpin inclination constant when the wheel is jumping up and down, but the track change is large (similar to the single-wishbone type), which causes severe tire wear and is rarely used now. For unequal-length double-wishbone suspension, as long as the length of the upper and lower booms is properly selected and optimized, and the reasonable changes can be used to make the track and front wheel alignment parameters within acceptable limits, to ensure that the car Has good driving stability. The unequal-length double-wishbone suspension has been widely used in the front and rear suspension of cars, and some sports cars and the rear wheels of racing cars also adopt this suspension structure.
Multi-link suspension A multi-link suspension is a suspension in which the position of a wheel is controlled by the combination of 3-5 rods. The multi-link type can make the wheel swing around an axis that has two fixed angles with the longitudinal axis of the car. It is a compromise between the cross arm type and the trailing arm type. The angle formed by the swing arm axis and the longitudinal axis of the car is appropriately selected. The advantages of the transverse arm type and the trailing arm type suspension can be obtained to different degrees, and it can meet different performance requirements. The main advantage of a multi-link suspension is that the change of track length and toe is small when the wheel is beating. Whether the car is driving or braking, it can steer smoothly according to the driver’s intention. The disadvantage is that the car There is shaft swing at high speeds.
Trailing arm suspension The trailing arm type independent suspension refers to a suspension structure in which a wheel swings in a longitudinal plane of a car, and is further divided into a single trailing arm type and a double trailing arm type. The single trailing arm suspension will cause a large change in the caster angle of the king pin when the wheel is jumping up and down, so the single trailing arm suspension is not used on the steering wheel. The two swing arms of a double trailing arm suspension are generally made of equal length to form a parallel four-bar structure. In this way, the caster angle of the king pin remains unchanged when the wheels bounce up and down. Double trailing arm suspensions are mostly used on steering wheels.
Candle suspension The structural characteristics of the candle-type suspension are that the wheels move up and down along the axis of the kingpin rigidly fixed to the frame. The advantage of a candle-type suspension is that when the suspension is deformed, the positioning angle of the king pin will not change, only the wheelbase and wheelbase will change slightly, so it is particularly beneficial to the car’s steering stability and driving stability. However, the candle type suspension has a big disadvantage: that the lateral force of the car when traveling is all borne by the king pin sleeved on the king pin sleeve, which causes the friction resistance between the sleeve and the king pin to increase, and the wear is more serious. Candlestick suspensions are not widely used.
Macpherson suspension The wheels of MacPherson suspension are also sliding suspensions along the king pin, but it is not exactly the same as the candle suspension. Its king pin can swing. The MacPherson suspension is swing arm and candle type. Combination of suspension. Compared with the double wishbone suspension, the advantages of the McPherson suspension are: compact structure, small changes in the front wheel positioning parameters when the wheels are bouncing, and good handling stability. The arrangement of the engine and steering system brings convenience; compared with the candle-type suspension, the lateral force on its spool has been greatly improved. Macpherson suspension is mostly used in the front suspension of small and medium-sized cars. Although Macpherson suspension is not the most technical suspension structure, it is still a durable independent suspension with Strong road adaptability.
Active suspension Active suspension is a new type of computer-controlled suspension developed in the past decade. It brings together technical knowledge of mechanics and electronics, and is a relatively complex high-tech device. The active suspension has the function of controlling the movement of the vehicle body. When the inertia of the car during braking or cornering causes the spring to deform, the active suspension will generate a force that is opposed to the inertial force, reducing the change in body position.
The seemingly simple suspension system combines a variety of forces, which determines the stability, comfort and safety of the car, and is one of the key components of modern cars.
The spring has two main functions: one is to act as a suspension system or a buffer between the chassis and the ground, that is, to maintain comfort, and the second is to keep the car on the ground when traveling on uneven roads.