1. Introduction
integral part of the backbone of the front and rear axle and front axle is the sub-frame. The frame is not a complete frame, but it supported by the front axle and a rear portion connected to the hanging bracket, and the suspension so that the axle is connected to the “n-frame”, a “sub-frame.” The role of sub-frame is vibration and noise barriers, reduce its direct access to the cabin, so they are mostly in luxury cars and sport utility vehicles, some of the car’s engine is mounted on a subframe. No sub conventional monocoque frame, the suspension is directly connected to the steel body. Therefore axles front and rear suspension rocker arm mechanism mostly spare parts, not assembly. Front and rear suspension may be mounted on the first subframe, a configuration of the axle assembly, which is then mounted to the car body together.
2, the main function
sub-frame Of course, this sub-frame with a suspension assembly, in addition to the design, installation can bring various advantages beyond convenience and, most important thing is for comfort and suspension stiffness increased.
not directly connected to the car engine body rigidity. But it is connected by a suspension to the vehicle body. We often see that the suspension of the vehicle body and the engine cushion rubber connection. As technology advances, more and more types of suspension, high-end vehicles with hydraulic suspension. Suspended role is to isolate engine vibration. That role under suspension, engine vibration can be transmitted to the cockpit as little as possible. Since the engine speed range in each segment has a different vibration characteristics, so good suspension means to effectively shield the respective vibration speed range section. That’s why we open some of the better matching of high-end car, whether the engine is 2000 rpm or 5000 rpm in, while driving reason not feel too much engine vibration.
the point of attachment of the subframe and the vehicle body like the engine mount the same. Usually a need to connect the axle assembly and the vehicle body by four suspension points, so can guarantee its connection stiffness, but also have a good vibration insulation effect.
This total suspension with a sub-frame5 steps can reduce the incoming vibrations. The first stage is absorbed by the soft rubber shock deformation of the tire of the table, which a large amount of deformation capable of absorbing high-frequency vibration, the second-stage shock absorbing deformation of the tire as a whole, which mainly absorb a slightly higher level than the first road vibration, such as vibration caused by stones and the like. The third stage is suspended on the vibration isolation rubber bush within each of the rocker arm connection point, this part mainly reduce the impact of the suspension assembly. The fourth stage is a suspension of up and down movement, this movement is mainly absorb long-wave shock, vibration is caused when too over-ditch threshold. Level 5 is a shock-absorbing suspension sub-frame, where the main absorption stage is not completely shield the first four vibration.
For the sub-frame so that, in the performance of the main object is to reduce the incoming road vibration and to improve the rigidity of the suspension system is connected, thus with the sub-frame chassis car driver will feel very solid, very compact. The suspension subframe hardness setting is also facing suspension tuning as the same can not avoid a contradiction. If the suspension subframe design is soft, it can be well isolated from vibration generated when cars, but too soft suspension sub-frame design will bring greater movement of deformation during high-speed turns, which can cause tires inaccurate positioning, thereby reducing the handling stability. Stiffer subframe mount, can bring very high connection stiffness, but very limited noise vibration isolation. So engineers tend to choose rubber gasket suitable for positioning stiffness and use models in the design and matching sub-frame.
3, advantages:
a good frame can bring the suspension 2 can be isolated connection stiffness road vibration bring good comfort cartridge 3 into the suspension member, increasing the versatility of the suspension, reduce development costs. 4. The cartridge member easy to install, reduces assembly costs.
4, disadvantages:
1 sub-frame increases a large vehicle weight, with the weight can be reduced while aluminum-But the increase will cost. 2. reduce driving stability, steering feel does not directly rarely used on the car.