Development history
Double wishbone independent suspension has an interesting name. It is said that this interesting name comes from a kind of turkey bone that people like to eat at Christmas in the west. When people start eating, they will make a wish on a V-shaped bone on the turkey, which is called the wishbone. Because there are two in the double wishbone suspension structure? Wish bone? Therefore, it is named double wishbone suspension.
The birth of double wishbone suspension is closely related to McPherson suspension. Their similarity is that the lower control arm is composed of a V-shaped or A-shaped front fork control arm, and the hydraulic shock absorber is used as a pillar to support the whole body. The difference is that the double wishbone suspension has an upper control arm connected to the strut shock absorber, which effectively enhances the overall reliability and stability of the suspension.
Structurally, McPherson suspension has only one lower control arm and one strut shock absorber.
The simplest structure makes its components usually multifunctional. For example, the strut shock absorber should act as the steering kingpin, not only to bear the weight of the vehicle itself, but also to deal with the jitter and impact from the road surface. If the McPherson suspension on one side of the vehicle is compressed by inertia when the vehicle is moving, the camber angle of the wheel will increase, so the more the suspension is compressed, the more difficult it is to control this deformation. Therefore, the application scope of McPherson suspension is mostly small or medium-sized cars. If the model level goes up, the McPherson suspension with simple structure will be somewhat inadequate.
Improve McPherson suspension? Fragile? It is necessary to adjust the suspension structure. Because the McPherson suspension has only two connecting parts, the lower control arm and the strut shock absorber, this forms a? l？ The shape of the structure, if you can? l？ If a control arm is added to the top of the V-shape, the structure of the suspension will be strengthened. Therefore, by implanting the control arm into McPherson suspension, the double wishbone suspension structure came into being. Compared with McPherson suspension, the physical characteristics of double wishbone suspension have changed obviously: when a suspension contracts due to inertia, the camber of the wheel changes relatively little, but the camber of the wheel can be improved by changing the relative length of the upper and lower control arms. Therefore, engineers have more freedom when designing and matching the double wishbone suspension, and can make the most reasonable adjustment for a certain characteristic of the car, such as sportiness or comfort.
In fact, at the beginning of vehicle chassis design, designers began to consider how to arrange complex suspension structures on the chassis to bring better handling or more stable comfort to the vehicle. In order to make the wheels fit the ground at any time and place, and achieve the unity of sportiness and riding comfort, designers often adopt double wishbone suspension structure, and increasing the damping of shock absorber and the hardness of spiral spring is also one of the countermeasures. At this time, McPherson suspension will increase the camber angle of the wheel because of the thin control arm, and at the same time increase the load on the inner side of the tire and aggravate the wear.
Because the traditional double wishbone suspension adopts a single guide structure, that is, the upper and lower control arms are connected with the strut shock absorber to control the up-and-down movement direction of the wheel, and the steering tie rod is connected with the kingpin to control the left and right direction of the wheel. From this point of view, shock absorption and steering are controlled by two independent mechanisms, but both of them have only one direction. With the continuous optimization and improvement of suspension structure, double wishbone suspension has developed a bidirectional control structure which can be responsible for wheel steering and up-and-down jitter at the same time. On Peugeot 407, the front suspension is called? Independent journal double fork front wheel system? Improved double wishbone suspension based on bidirectional control. In the improved suspension, the steering knuckle and the steering knuckle bracket are used to replace the situation that only the upper and lower control arms are used to restrain the wheel, and the steering of the wheel is completed by the steering knuckle hinge installed between the steering knuckle brackets. In the front suspension with steering mechanism, the steering knuckle bracket is connected with the steering knuckle ball hinge, stabilizer bar, hydraulic shock absorber and upper and lower arms. These two new parts are responsible for wheel runout and steering respectively. The new structure makes each part bear much less force than the traditional double wishbone, and the reliability is improved a lot. In addition, the dynamic performance is greatly improved, and the new double wishbone suspension obtains smaller kingpin camber and camber, and the automatic steering wheel positioning effect is more obvious.
aufbau principle
The double wishbone suspension consists of two upper and lower V-shaped or A-shaped control arms with different lengths and a strut hydraulic shock absorber. Generally, the upper control arm is shorter than the lower control arm. One end of the upper control arm is connected with the strut shock absorber, and the other end is connected with the vehicle body; One end of the lower control arm is connected to the wheel and the other end is connected to the vehicle body. The upper and lower control arms are also connected by connecting rods, and the connecting rods are also connected to the wheels. In the whole suspension structure, by connecting multiple fulcrums, the integrity of the upper and lower control arms and the whole suspension is improved.
If it is a front-wheel drive vehicle, the double wishbone suspension assembled on the front wheel is equipped with steering mechanism besides the transmission mechanism between the upper and lower control arms, which makes its structure much more complicated than that without steering mechanism on the rear wheel. In the steering mechanism, the steering kingpin is determined by the connection position and angle between the steering wheel and the upper and lower control arms, and the steering wheel can rotate around the kingpin and jump up and down with the lower control arm. In the double wishbone suspension, the ball joint is usually used to meet the movement needs of the front wheel: the joint between the upper and lower control arms and the steering kingpin should not only support the front wheel to realize steering, but also control the up and down jitter of the wheel. However, due to the length difference between the upper and lower control arms, the design of double wishbone suspension is also put forward a severe test. If the length difference between the upper and lower control arms is too small, the wheel jitter will cause the left and right wheel gaps to be too large, which will accelerate the external wear of the tire. On the other hand, if the length difference between the upper and lower arms is too large, the camber angle will be too large when the wheel turns, which will accelerate the wear of the inner side of the tire. Therefore, by increasing the length of the upper and lower control arms, the variation of the wheel track can be reduced and the variation of the camber angle can be controlled.
In addition, the upper and lower control arms of the double wishbone suspension can offset the lateral force, so that the strut shock absorber can no longer bear the lateral force, but only deal with the up and down jitter of the wheel, so it has good directional stability in corners. Known? King of the bend? The front suspension of the prestigious mazda 6 is a double wishbone suspension. Therefore, when mazda 6 is driving in a corner, the roll is small, and the overall feeling of the car body is well maintained.
technical characteristics
superiority
Large lateral stiffness, excellent anti-roll performance, good grip performance and clear road feel.
First of all, the precise control of positioning parameters makes the wheel close to the ground, and the strong lateral rigidity provides good lateral support. The advantages of this structure are obvious for the handling performance of the vehicle. It is not only the first choice for Ferrari, Lamborghini, Maserati and other super sports cars, but also the shadow of the double wishbone can still be seen in the suspension structure adopted by F 1 racing cars today. The two triangular rocker arms also have excellent torsional strength and lateral stiffness, so the double wishbone suspension structure is often used in hard-core SUVs or pickup trucks, and the structure of the front double wishbone and the rear integral bridge is also a classic structure of hard-core off-road SUVs. For example, Grand Cherokee, Toyota Prado and Volkswagen Touareg all adopt double-arm suspension structure.
disadvantaged
The manufacturing cost is high and the setting of suspension positioning parameters is complicated.
Compared with McPherson suspension, its structure is more complicated, it takes up more space and costs more, so it is not suitable for small front suspension. In addition, the determination of positioning parameters requires accurate calculation and adjustment, and also requires higher technical strength of manufacturers.
Application vehicle type
Compared with McPherson suspension, double wishbone independent suspension has upper rocker arm, which not only needs
It takes up a lot of space, and its positioning parameters are difficult to determine. Therefore, due to the consideration of space and cost, this kind of suspension is generally not adopted for the front axle of small cars. However, it has the advantages of small roll, many adjustable parameters, large tire contact area and excellent grip performance, so most pure sports cars adopt double wishbone suspension, which can be said to be a suspension born for sports. Ferrari, Maserati and other super sports cars and F 1 Formula racing cars all use double wishbone front suspension. FAW Toyota Crown and Reiz also adopted double wishbone front suspension. Domestic cars with double wishbone front suspension mainly include FAW Toyota Crown and FAW Toyota Reiz, as well as Audi's luxury SUVQ7 and Volkswagen Touareg. Pure domestic products include China Kubao produced in 2007 and Ruiqi G5 produced by Chery. It is the first self-developed car with double wishbone structure, and the subsequent models will adopt more advanced air suspension system.
It should be noted that double wishbone suspension and double wishbone suspension have many characteristics, but the structure is simpler than double wishbone suspension, which can be called a simplified version of double wishbone suspension. Like the double wishbone suspension, the transverse stiffness of the double wishbone suspension is also large, and the upper and lower rocker arms are generally used. The Civic with double wishbone suspension at the rear of the car has better sportiness, and Honda Accord and mazda 6 both adopt double wishbone suspension at the front of the car.
The design of double wishbone suspension tends to be sporty, and its performance is better than McPherson suspension, but it is slightly worse than the real double wishbone suspension and multi-link front suspension. Domestic models with double wishbone front suspension mainly include: Guangzhou Honda Accord, FAW Car mazda 6 and Beijing Benz-Dyke Chrysler 300C. And Dongfeng Honda Civic with double wishbone rear suspension. Volkswagen luxury SUV Touareg front and rear suspension adopts double wishbone independent suspension.
Although the double wishbone independent suspension has many advantages, such as excellent lateral support and accurate wheel direction control. Due to the structure of upper and lower control arms, the response speed of wheels is slower than that of other forms of suspension due to the over-stability characteristics, and the structure of upper and lower control arms also leads to the increase of lateral installation space of this suspension. Therefore, double wishbone suspension often appears in luxury cars, full-size SUVs, pickup trucks and even super sports cars with wide bodies. For example, the familiar Cadillac Saiwei SLS, Citroen C6, Audi Q7, Volkswagen Touareg, and even the domestic ZTE Weiwei Tiger Leather Card, the front suspension adopts double wishbone structure. For sports cars such as Lamborghini Gallardo and Maserati 3000GT, which pay attention to handling performance, the front and rear suspensions are suspended with double wishbones, which shows that the double wishbones have a wide range of applications, and it is important that they can provide good lateral support for the body.
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