Chassis vehicle- the most important high-tech group, on the work of which many characteristics of the vehicle depend. The serviceability of all its components and assemblies is a guarantee of safety on the road. In turn, the core of the chassis is the suspension of the car. The damping system serves to connect the wheels with the car body, and its main goal is to smooth out as much as possible all vibrations caused by roadway defects, and at the same time effectively realize the energy of the vehicle's movement.
Structure
TO modern machines there are many requirements. They must be well controlled and at the same time stable, silent, comfortable and safe. To realize all these wishes, engineers need to carefully consider the suspension device.
To date, there is no universal standard. Each automaker has its own tricks and modern developments in its arsenal. However, all types of suspensions are characterized by the presence of such objects:
- elastic element.
- Guiding part.
- stability stabilizer.
- shock absorber devices.
- Wheel support.
- fasteners.
elastic element
Automobile suspension contains elastic elements made of metal and non-metal parts. They are necessary to redistribute the shock load received by the wheels when meeting with road irregularities. Metal elastic parts include springs, torsion bars and springs. Non-metallic elements are rubber bumpers and buffers, pneumatic and hydropneumatic chambers.
metal objects
Historically, the very first appeared springs. From the point of view of design, these are metal strips of different lengths interconnected. In addition to the effective redistribution of the load, the springs absorb well. Most often they are used in the undercarriage of trucks.
Torsion bars are sets of plates or rods that work in twisting. Usually the rear suspension of the car is torsion bar. Devices of this type are used, in addition, by Japanese and American manufacturers of off-road vehicles.
Metal springs are part of the running gear of any modern car. These elements can have constant or variable stiffness. Their elasticity depends on the geometry of the rod from which they are made. If the diameter of the bar varies throughout, then the spring has a variable stiffness. Otherwise, the elasticity is constant.
non-metal objects
Elastic non-metallic parts are used in conjunction with metal parts. Rubber elements - bumpers and buffers - not only participate in the redistribution of dynamic loads, but also absorb.
Pneumatic and hydropneumatic chambers are used in active suspension designs. Their action is determined by the properties of only compressed air (pneumatic chambers) or gas and liquid (hydropneumatic chambers). These elastic elements make it possible to change the vehicle clearance and the stiffness of the damping system automatically. In addition, they provide a high level of running smoothness. Hydropneumatic chambers were the first to be developed. They showed up in cars. brands Citroen in the 1950s. Today, pneumatic and hydropneumatic suspensions are optionally equipped with business class cars: Mercedes-Benz, Audi, BMW, Volkswagen, Bentley, Lexus, Subaru, etc.
Guide part
Suspension guide elements are racks, levers and swivel joints. Their main functions:
- Keep the wheels in the correct position.
- Maintain the trajectory of the wheels.
- Provide a connection between the shock absorption system and the body.
- Transfer the energy of movement from the wheels to the body.
Roll Stabilizer
The vehicle suspension would not provide the vehicle with the necessary stability without a stabilizing device. It fights the centrifugal force that tends to tip the car over when cornering and reduces body roll.
Technically, the stabilizer roll stability- This is a torsion bar that connects the depreciation system and the body. The higher its rigidity, the better car keeps the road. On the other hand, excessive elasticity of the stabilizer reduces suspension travel and reduces the smoothness of the vehicle.
As a rule, both axles of the machine are equipped with anti-roll bars. But if the rear suspension of the car is torsion bar, the device is installed only in front. Mercedes-Benz engineers were able to completely abandon it. They developed a special type of adaptive suspension with electronic body position control.
Shock-absorbing devices
In order to soften strong vibrations, the suspension is supplied with shock absorbers. These objects are pneumatic or fluid cylinders. There are two main types of shock absorbers:
- Unilateral.
- Bilateral.
Single-sided shock absorbers are longer than double-sided ones. They provide a very smooth ride. However, when driving on roads with poor coverage, one-way shock absorbers do not have time to return the suspension to its original state before the next bump, and it “breaks through”. For this reason, double-sided "vibration dampers" have become more common.
Wheel support
Wheel supports are necessary to accept and redistribute the loads on the wheels.
Fasteners
Spherical bearing
Fasteners are needed so that the suspension of the car is a single whole. To connect nodes and assemblies, three types of connections are used:
- Bolted.
- Hinged.
- Elastic.
Bolted fasteners are rigid. They are necessary for the fixed articulation of objects. Swivel joints include a ball joint. It is an important part of the front suspension and ensures that the drive wheels can turn properly. Elastic fasteners are silent blocks and rubber-metal bushings. In addition to the function of connecting parts and attaching them to the body, these objects prevent the spread of vibrations and reduce noise.
All elements of the chassis are interconnected and most often perform several functions at the same time, so the definition of whether a spare part belongs to a particular group is conditional.
The suspension of a car is a set of elements that provide an elastic connection between the body (frame) and the wheels (bridges) of the car. The suspension is mainly designed to reduce the intensity of vibration and dynamic loads (shocks, shocks) acting on a person, a transported load or structural elements of a car when it is moving on an uneven road. At the same time, it must ensure constant contact of the wheel with the road surface and effectively transmit the driving force and braking force without deviating the wheels from the corresponding position. Proper suspension operation makes driving comfortable and safe. Despite its apparent simplicity, the suspension is one of the most important systems of a modern car and has undergone significant changes and improvements over the history of its existence.
History of appearance
Attempts to make the movement of the vehicle softer and more comfortable were made even in carriages. Initially, the axles of the wheels were rigidly attached to the body, and every bump in the road was transmitted to the passengers sitting inside. Only soft cushions on the seats could increase the level of comfort.
Dependent suspension with transverse springs
The first way to create an elastic "layer" between the wheels and the carriage body was the use of elliptical springs. Later, this solution was borrowed for the car. However, the spring has already become semi-elliptical and could be installed transversely. A car with such a suspension was poorly controlled even at low speeds. Therefore, soon the springs began to be installed longitudinally on each wheel.
The development of the automotive industry also led to the evolution of the suspension. Currently, there are dozens of their varieties.
The main functions and characteristics of the car suspension
Each suspension has its own characteristics and working qualities that directly affect the handling, comfort and safety of passengers. However, any suspension, regardless of its type, must perform the following functions:
- Absorption of shocks and shocks from the side of the road to reduce the load on the body and improve driving comfort.
- Vehicle stabilization while driving by ensuring constant contact of the wheel tire with pavement and limiting excessive body roll.
- Saving the specified travel geometry and wheel position to maintain steering precision while driving and braking.
Drift car with rigid suspension The rigid suspension of the car is suitable for dynamic driving, which requires an immediate and precise reaction to the driver's actions. It provides low ground clearance, maximum stability, resistance to roll and body sway. Mainly applied to sports cars.
Luxury car with energy-intensive suspension Most passenger cars soft suspension is used. It smooths out bumps as much as possible, but makes the car somewhat rolly and less manageable. If adjustable stiffness is required, a screw suspension is mounted on the car. It is a shock absorber strut with a variable spring force.
SUV with long travel suspension Suspension travel is the distance from the extreme upper position of the wheel when compressing to the extreme lower position when hanging the wheels. Suspension travel largely determines the "off-road" capabilities of the car. The greater its value, the greater the obstacle can be overcome without hitting the limiter or without sagging of the drive wheels.
suspension device
Any car suspension consists of the following main elements:
- elastic device– takes the load from the unevenness of the road surface. Types: springs, springs, pneumatic elements, etc.
- damping device— dampens vibrations of the body when driving through bumps. Types: all types.
- Guide device—provides a given movement of the wheel relative to the body. Kinds: levers, transverse and jet rods, springs. To change the direction of impact on the damping element in pull-rod and push-rod sports suspensions, rockers are used.
- Roll Stabilizer- Reduces body roll.
- Rubber-metal hinges- provide elastic connection of the suspension elements with the body. Partially cushion, soften shocks and vibrations. Types: silent blocks and bushings.
- Suspension travel stops- limit the suspension travel in extreme positions.
Pendant classification
Basically, suspensions are divided into two large types: and independent. This classification is determined by the kinematic diagram of the suspension guide.
dependent suspension
The wheels are rigidly connected by means of a beam or a continuous bridge. The vertical position of the pair of wheels relative to the common axis does not change, the front wheels are swivel. Device rear suspension similar. It happens spring, spring or pneumatic. In the case of installing springs or air springs, it is necessary to use special rods to fix the bridges from moving.
Differences between dependent and independent suspension - simple and reliable in operation;
- high load capacity.
- poor management;
- poor stability at high speeds;
- less comfort.
Independent suspension
The wheels can change vertical position relative to each other while remaining in the same plane.
- good handling;
- good vehicle stability;
- great comfort.
- more expensive and complex design;
- less reliable operation.
Semi-independent suspension Semi-independent suspension or torsion beam- This is an intermediate solution between dependent and independent suspension. The wheels still remain connected, however, there is the possibility of their slight movement relative to each other. This property is provided due to the elastic properties of the U-shaped beam connecting the wheels. Such a suspension is mainly used as a rear suspension for budget cars.
Types of independent suspensions
McPherson
- the most common front axle suspension modern cars. Lower arm connected to the hub by means of a ball joint. Depending on its configuration, a longitudinal jet thrust. A suspension strut with a spring is attached to the hub assembly, its upper support is fixed to the body.
The transverse link, mounted on the body and connecting both levers, is a stabilizer that counteracts the roll of the car. The lower ball joint and shock absorber cup bearing allow the wheel to turn.
The rear suspension parts are made according to the same principle, the only difference is the lack of the ability to turn the wheels. The lower arm has been replaced with longitudinal and transverse rods that fix the hub.
- simplicity of design;
- compactness;
- reliability;
- inexpensive to manufacture and repair.
- average handling.
Double wishbone front suspension
More efficient and complex design. The second transverse arm acts as the upper attachment point of the hub. A spring or can be used as an elastic element. The rear suspension has a similar structure. This suspension scheme provides better handling of the car.
Air suspension
air suspension The role of the springs in this suspension is performed by compressed air bellows. With the possibility of adjusting the height of the body. It also improves ride comfort. Used on luxury cars.
hydraulic suspension
Lexus hydraulic suspension height and stiffness adjustment The shock absorbers are connected to a single closed loop with hydraulic fluid. allows you to adjust the stiffness and height ground clearance. If the vehicle has a control electronics and a function, it automatically adjusts itself to road and driving conditions.
Sports independent suspensions
screw suspension(coilovers) Screw suspension, or coilovers - suspension struts with the ability to adjust the stiffness directly on the car. Thanks to threaded connection the lower stop of the spring, you can adjust its height, as well as the amount of ground clearance.
Push-rod and pull-rod hangers
These devices were developed for racing cars with open wheels. The basis is a two-lever scheme. The main feature is that the damping elements are located inside the body. The design of these types of suspension is very similar, the difference lies only in the location of the load-bearing elements.
The difference between push-rod and pull-rod sports suspensions Push-rod sports suspension: load-bearing element - pushrod, works in compression.
Suspension- a set of devices that provide an elastic connection between the sprung and unsprung masses Suspension reduces the dynamic loads acting on the sprung mass. It consists of three devices:
- elastic
- guiding
- damping
elastic device 5, vertical forces acting from the road are transferred to the sprung mass, dynamic loads are reduced and ride smoothness is improved.
Rice. Rear suspension on oblique levers of BMW cars:
1 – cardan shaft driving axle; 2 - support bracket; 3 - axle shaft; 4 - stabilizer; 5 - elastic element; 6 - shock absorber; 7 - suspension guide lever; 8 - bracket support
Guide device 7 - a mechanism that perceives the longitudinal and lateral forces acting on the wheel and their moments. The kinematics of the guide device determines the nature of the movement of the wheel relative to the carrier system.
damping device() 6 is designed to dampen vibrations of the body and wheels by converting vibration energy into heat and dissipating it into the environment.
The design of the suspension must provide the required smoothness of movement, have kinematic characteristics that meet the requirements of vehicle stability and controllability.
dependent suspension
Dependent suspension is characterized by the dependence of the movement of one wheel of the axle on the movement of the other wheel.
Rice. Scheme of dependent wheel suspension
The transfer of forces and moments from the wheels to the body with such a suspension can be carried out directly by metal elastic elements - springs, springs or using rods - a rod suspension.
Metal elastic elements have a linear elastic characteristic and are made of special steels with high strength at large deformations. Such elastic elements include leaf springs, torsion bars and springs.
Leaf springs are practically not used on modern passenger cars, with the exception of some models of multi-purpose vehicles. It can be noted the models of passenger cars that were previously produced with leaf springs in the suspension, which continue to be used at the present time. Longitudinal leaf springs were installed mainly in the dependent wheel suspension and served as an elastic and guiding device.
On passenger cars and trucks or minibuses, springs without springs are used, on trucks- with suspension brackets.
Rice. Springs:
a) - without a sprung; b) - with a sprung
Springs as elastic elements are used in the suspension of many cars. In the front and rear suspensions manufactured by various companies in most passenger cars, helical coil springs with a constant bar section and winding pitch are used. Such a spring has a linear elastic characteristic, and the necessary characteristics are provided by additional elastic elements made of polyurethane elastomer and rubber rebound buffers.
On passenger cars Russian production in suspensions, cylindrical helical springs with a constant rod cross section and pitch are used in combination with rubber impact buffers. On cars from manufacturers in other countries, for example, the BMW 3 Series, a barrel-shaped (shaped) spring with a progressive characteristic is installed in the rear suspension, achieved due to the shape of the spring and the use of a variable section bar.
Rice. Spiral springs:
a) a cylindrical spring; b) barrel spring
On a number of vehicles, a combination of coil and shaped springs with variable bar thickness is used to provide progressive performance. The shaped springs have a progressive elastic characteristic and are called "mini-blocks" for their small height. Such shaped springs are used, for example, in the rear suspension of Volkswagen, Audi, Opel, etc. Shaped springs have different diameters in the middle part of the spring and along the edges, and miniblock springs also have a different winding pitch.
Torsion bars, as a rule, of round section are used on cars as an elastic element and a stabilizer.
The elastic torque is transmitted by the torsion bar through splined or square heads located at its ends. Torsion bars on a car can be installed in the longitudinal or transverse direction. The disadvantages of torsion bars include their large length necessary to create the required stiffness and suspension travel, as well as the high alignment of the splines at the ends of the torsion bar. However, it should be noted that torsion bars have a small mass and good compactness, which allows them to be successfully used on passenger cars of medium and high classes.
Independent suspension
Independent suspension ensures that the movement of one wheel of the axle is independent of the movement of the other wheel. According to the type of guiding device, independent suspensions are divided into lever and MacPherson suspensions.
Rice. Scheme of independent linkage wheel suspension
Rice. MacPherson independent suspension scheme
Link suspension- suspension, the guiding device of which is a lever mechanism. Depending on the number of levers, there can be double-lever and single-lever suspensions, and depending on the swing plane of the levers - cross-lever, diagonal-lever and longitudinal-lever.
List of types of car suspensions
This article discusses only the main types of car suspensions, while there are actually many more types and subspecies of them, and besides, engineers are constantly developing new models and refining old ones. For convenience, here is a list of the most common. In the following, each of the suspensions will be considered in more detail.
- Dependent suspensions
- On a transverse spring
- On longitudinal springs
- With guide levers
- With support pipe or drawbar
- "De Dion"
- Torsion-lever (with connected or mated levers)
- Independent suspensions
- With swing axles
- On trailing arms
- spring
- Torsion
- hydropneumatic
- Pendant "Dubonnet"
- On double trailing arms
- On slanting levers
- On double wishbones
- spring
- Torsion
- Spring
- On rubber elastic elements
- Hydropneumatic and pneumatic
- Multi-link suspensions
- candle pendant
- Pendant "MacPherson" (swinging candle)
- On longitudinal and transverse levers
- Active suspensions
- Pneumatic suspensions
Due to the perception of acting forces and damping of vibrations. The suspension is part of the chassis of the car.
Vehicle suspension includes guiding and elastic elements, damping device, anti-roll bar, wheel support, as well as fastening elements.
Guide elements provide connections and transfer of forces to the car body. The guide elements determine the nature of the movement of the wheels relative to the car body. All kinds of levers are used as guide elements: longitudinal, transverse, double, etc.
The elastic element perceives the load from the unevenness of the road, accumulates the received energy and transfers it to the car body. distinguish between metallic and non-metallic elastic elements. Metal elastic elements are represented by a spring, a spring and a torsion bar.
Coiled springs made of round steel rods are widely used in passenger car suspensions. The spring can have constant and variable stiffness. A coil spring is usually of constant stiffness. Changing the shape of the spring (using a metal bar of variable cross section) allows you to achieve variable stiffness.
The leaf spring is used on trucks. The torsion bar is a metal elastic element that works on twisting.
Non-metallic include rubber, pneumatic and hydropneumatic elastic elements. Rubber elastic elements (buffers, chippers) are used in addition to metal elastic elements.
The operation of pneumatic elastic elements is based on the elastic properties of compressed air. They provide a high ride smoothness and the ability to maintain a certain amount of ground clearance.
The hydropneumatic elastic element is represented by a special chamber filled with gas and working fluid, separated by an elastic partition.
The damping device (shock absorber) is designed to reduce the amplitude of vibrations of the car body caused by the operation of the elastic element. shock absorber operation is based on hydraulic resistance that occurs when fluid flows from one cylinder cavity to another through calibration holes (valves).
There are the following designs of shock absorbers: single-pipe(one cylinder) and two-pipe(two cylinders). Double-tube shock absorbers are shorter than single-tube shock absorbers, they have a large scope, therefore they are more widely used on a car.
For single-tube shock absorbers, the working and compensation cavities are located in one cylinder. Changes in the volume of the working fluid caused by temperature fluctuations are compensated by the volume of the gas cavity.
A double-tube shock absorber includes two tubes located one inside the other. The inner tube forms a working cylinder, and the outer tube forms a compensation cavity.
In a number of designs of shock absorbers, it is possible to change the damping properties:
- manual adjustment of the valves before installing the shock absorber on the car;
- the use of electromagnetic valves with a variable area of the calibration holes;
- change in the viscosity of the working fluid due to the influence of an electromagnetic field.
Trailing arm suspension is used as the rear suspension of the car. Other types of suspensions can be used both on the front and on rear axle car. The most common on passenger cars received: on the front axle - MacPherson suspension, on the rear axle - multi-link suspension.
Some off-road and premium vehicles are fitted with air suspension, which uses air springs. A special place in the suspension design is occupied by hydropneumatic suspension, developed by Citroen. The design of pneumatic and hydropneumatic suspension is based on known types of suspensions.
Currently, many automakers are equipping their vehicles with active suspension. Variety active suspension is the so-called. adaptive suspension, which provides for automatic adjustment of the damping capacity of shock absorbers.