What is a variable suspension, and what has it "changed"?
When dealing with different road conditions, the suspension is constant due to the spring stiffness and the damping coefficient of the shock absorber, so engineers want to use "variable suspension" to meet the needs of different road conditions. Variable suspension usually has two implementation forms, adjusting the height and softness of the suspension. So what methods have the respective manufacturers adopted to achieve it?
1. air suspension is the most ideal and widely used
The working principle of air suspension is simply to replace the traditional coil spring with a rubber airbag, and then collect it through the control unit The air compressor and other devices inject air into the airbag to realize the height adjustment of the vehicle body and the soft and hard suspension of the suspension. For example, on some bumpy roads, the control unit adjusts to reduce the air pressure in the airbag , Making the suspension "softer" improves the ride comfort of the occupants in the car, while driving on normal paved roads will increase the pressure, making the suspension "hard" and improving the driving stability of the vehicle. In addition to being hard, it can also adjust the height of the vehicle to ensure vehicle passability and driving stability. Therefore, air suspension can meet a variety of needs and is the most ideal suspension form at present. However, the durability of the airbag becomes its biggest shortcoming after the longevity, and the high cost makes it only suitable for some It is only used on high-end models.
2. Cadillac MRC electromagnetic suspension
Cadillac’s MRC electromagnetic suspension is an active variable suspension, which can change the size of the shock absorber according to the road conditions ahead. It uses magnetorheological technology, that is, adding magnetic oil inside the shock absorber,Then through the electrode, to change the magnetic oil particle arrangement structure, its control unit can achieve 1000 calculations per second, so as to achieve more delicate and accurate damping adjustment. The most intuitive experience in daily driving is that when the vehicle brakes suddenly, the vehicle will nod due to the inertia and center of gravity shift, and the electromagnetic suspension will make the front suspension harder in advance. Suppress the brake nodding amplitude; and when turning, it will provide stronger chassis support to the outer wheels, thereby reducing roll. Although the performance of MRC is very good, its fatal disadvantage is that it is relatively poor in standing and durability. For example, the electromagnetic suspension may fail in a long-term inventory car, and the internal shock absorber is not ordinary hydraulic fluid, but special purpose. Magnetic oil, when it comes to replacement, is also a significant cost.
3. Peugeot AMVAR variable damping suspension
Compared with Cadillac’s electromagnetic suspension, Peugeot’s variable damping suspension is relatively simple. It has a set of four front and rear wheels. The electronically controlled hydraulic shock absorber, and then according to the data provided by the vehicle height sensor on the four wheels and the three acceleration sensors on the vehicle body, the internal of the shock absorber is changed through the electric valve built in the shock absorber The oil passage of the shock absorber can change the oil flow to achieve the effect of changing the damping of the shock absorber. Therefore, Peugeot’s plan is to achieve a balance between performance and cost, but it also has problems. For example, the rear suspension of Peugeot 508L adopts a spring barrel integrated oblique arrangement, resulting in a short suspension stroke and difficulty in taking into account comfort even when driving. The mode is adjusted to "comfort" and the suspension is also stiffer, while the sports mode will be stiffer.
Whether it is a normal suspension or a variable suspension, manufacturers have made a trade-off between the corresponding cost and performance, and how consumers choose is also a trade-off between cost and demand.
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