Air suspension with adjustable stiffness and ride height
Air suspension with adjustable stiffness and ride height is set
to off-road vehicles or vehicles business class and is used to create
additional comfort when driving.
Air suspension will reduce the
ride height depending on the speed, and the center of gravity down and
significantly increased exchange rate stability. The driver can choose
from several levels of clearance.
The pressure in the strut is
created by a separate compressor. All elements are combined with plastic
ducts and the air flow is regulated by solenoid valves. The data from
four sensors located on the axes, and three acceleration sensors mounted
on the body, the control unit receives an adaptive air suspension.
Thus, the computer in a few milliseconds gives the command to
reconfigure each shock absorber, suspension depends on road.
Damping
force is adjusted automatically. Under a heavy load in the harness
supplied additional air that is discharged with decreasing load. In
addition, the adaptive air suspension provides auto adjusting the ground
clearance. In this case, the clearance of the car, regardless of the
load remains within the specified values.
Infinitely variable
rigidity air suspension is designed to provide a high level of comfort
thanks to the computer control of the testimony of the various types of
sensors.
While there is no need for tougher the suspension, for
example, in high-speed driving on the road with good pavement,
suspension remains comfortably soft. Changing the damping of each wheel
individually reduces the risk of body movements, which could affect
passenger comfort.
In cornering, or when driving off adaptive suspension automatically reduces the buildup of body and pecks.
The principle of operation of air suspension vehicle.
Characteristics
of suspension affects many operational qualities of the car: ride,
comfort, driving stability, durability, as the machine itself, and a
number of its parts and components. In heavy traffic conditions, it is
possible the suspension, not the engine power, determine the average and
maximum speed.
Experience in operating commercial vehicles shows
that the rough roads average speed drops to 35-40%, fuel consumption
increases by 50-70%, turnaround decreases by 35-40%. The productivity of
vehicles is reduced by 32-36%, and the cost of transport increased by
50-60%. Add to that the loss caused by overspending metal, fuel, rubber,
and the incremental cost of labor. To reduce these losses can or
improve roads, which is expensive, or improve the car's suspension,
which is even more expensive, but in terms of thousands of cars is
cheaper.
All the same road with a smooth surface impose the
suspension is very strict. After all, speed is constantly increasing,
and the requirements for handling and stability of automobiles and
trains harder. Placing three-section pnevmoelement.
in equalizing rear axle car Tatra-815
Analysis of the
design of the car shows that the weighting of the vehicle determined by
the ratio of the payload to the weight of itself, is constantly growing.
The desire for minimum curb weight, increase the weight coefficient of
the vehicle and wearing comfort leads to the fact that the suspension
with steel springs not
always able to fit into the requirements for them. In many cases, the suspension should:
- The maximum smoothness without significant mutual displacements sprung and unsprung parts of the car;
- The minimum clearance between the body (chassis) and axles;
- Constant height of a step or floor level when the load changes.
If
the linear characteristics of the traditional elastic elements can not
achieve acceptable natural frequency equal to 90-120 min-1, forcing
designers to contact with non-linear elastic elements, progressive
characteristic: Pneumatic and hydro-pneumatic, has a number of
advantages.
First, these elastic elements have more energy in the
main working range and large deflections, and hence, reducing the
amplitude of the oscillations, reducing the amount of energy absorbed
shocks, facilitate adjustment. In the suspensions with steel elastic
elements and performance density is achieved only through a strong
design complexity.
The second advantage - the ease of automatic
control and dynamic stiffness of the suspension in accordance with the
load, which allows you to get a great ride and improve the performance
of the other. For the same size Suspension allows you to have a high
degree of commonality for different duty vehicles with a significant
difference in the magnitude of the sprung mass. This is the third
advantage. Fourth, pnevmoelementy have extremely long life, unattainable
for steel elastic elements. Such as cylinders buses GMC nursed to 1
million miles.
Permanent position of the body facilitates
ensuring the correct kinematic suspension and steering actuator lowers
the center of gravity of the car and, therefore, increase its stability.
At any load provided proper position lights for safer night driving. It
- five. Sixth, to improve vehicle stability when braking on air
suspension often given another function: just adjust the braking forces
at the wheels depending on the load changes on them.
Modern suspension (cargo) of the vehicle consists of three main components:
1. Elastic elements, which receive dynamic loads between the body or frame vehicle and road.
2. Elements, absorbing vibration suspension.
3. Node is responsible for stabilizing the vehicle relative to the plane of the road.
At
this point in trucks, a variety of vehicle suspension design and
engineering of the elastic elements. First of all, it yourself car
tires, which efficiently absorb minor road irregularities. The larger
wheels and lower the pressure in it, the greater the obstacle car
crossed without much impact on the load frame. Heavy dump trucks with
their huge wheels do without additional suspension components, as their
tires effectively dampen road roughness. Slow wheel tractors and
machinery in the form of an elastic element content with only air in the
tires.
Second in age and frequency of use in modern technology
elastic elements are springs. They come in different model, have a
different production technology, but they are the most massively used in
modern trucks, and they can be seen as a long-haul tractor, and on
construction equipment, urban retail delivery vehicles, military trucks
and racing. If previously installed on trucks thick packets
korotkolistovyh springs, on modern machines have significantly reduced
the number of springs, up to one-on some models, and the length
increased, which improved the ride and reduced structural weight. If
European manufacturers prefer long spring, their colleagues in the U.S.
soon. Therefore trucks with the North American continent tougher on the
go.
Air suspension widespread in Europe and the U.S. was 30-40
years ago. Its main advantage over the spring in the lower weight, it
supplies more cheaply, and the truck has a better ride. Factory price of
the truck with air suspension is higher than the machine with a spring,
but the replacement pads in operation for less than the whole spring.
In addition, trucks with air suspension smaller break asphalt roads, so
most long-haul trucks are equipped with bellows. Disadvantage of this
suspension is that it requires additional air valves and tubes and more
powerful air compressor. This system is afraid of water and the mud, so
the construction techniques used cup spring suspension. However, there
is the Dutch manufacturer of heavy construction equipment and Terberg
Ginaf, which are actively used air suspension of his own design for
trucks.
Air bags do not have a rigid connection to the frame of
the truck, and that the bridge does not "walk" in the design of the
vehicle suspension used longitudinal and transverse thrust. This also
complicates and increases the cost of construction.
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| Air Suspension |
In the case of schemes chetyrehballonnoy suspension bridge but
two (usually) longitudinal jet transverse rods requires (usually
V-shaped) of thrust. If the manufacturer sets the bridge two air bags,
the suspension design used trailing (properly called the jet thrust).
Rigidity is increased, then the transverse rod put one or even without
it. That silent blocks and bushes jet rods require attention and
periodic maintenance and replacement. roads at normal thrust nursed
250-350 thousand miles. In our case, they are unlikely to last for more
than 200 thousand kilometers. If you yawn when replacement thrust, you
can "get" for the repair of frogs, of course, if the time before power
does not coincide with the axis of the road train of broken bushes, not
deploy your truck across the road on the ice.
It should be noted that
today's manufacturers of trucks widely used combinations suspension,
consisting of springs and pnevmoelementov.
In North America for
construction equipment commonly used rubber-cast pads as an elastic
element. Such a suspension spring is much easier, and it does not have
the disadvantages of air suspension. Price rubber suspension is not very
different from the spring. But it is quite tough, and without air
suspension driver's seat can not do. Unfortunately, this type of
suspension is almost common.
Torsion bars are used primarily for
military applications. True, the famous brand Tatra trucks in some
building models are widely used torsion bars, both independently and in
combination with bellows. By light delivery truck Japanese and Korean
manufacturers front independent suspension sometimes made on the torque.
The
springs are used primarily for off-road all-wheel drive cars with
independent wheel suspension. In the German Army enough trucks MAN, with
6x6 and independent spring suspension on all wheels.
In order to
extinguish the buildup of the truck used in the design of the car shock
absorbers. They can be either single or double action. At the moment,
shock absorbers, usually hydraulic. On European motorways and European
climate shocks "live" 300-400 thousand miles. On our roads increases the
load on the suspension several times. well and frost can "kill" the
shock absorbers and 10 thousand kilometers: they flow, are broken or
torn rubber grommets "ears."
Sport trucks, special purpose
vehicles and military vehicles are equipped with hydropneumatic struts.
This is not a new invention, as in military vehicles are used for a long
time. But only recently started using these racks and the civil
engineering.
Hydropneumatic front are kind of active dampers
effectively perceive the increased loads and large amplitude
oscillations quenching. They can change their stiffness and other
characteristics depending on the application. They are used, usually in
trucks with leaf spring suspension. Such machines with the suspension
kept jumping and flying tens of meters without affecting the truck. the
potential of such a great suspension at various rally raids and
demonstrations of military equipment.
Last two years, special
vehicles and not only on him began to install a new generation of
hydro-pneumatic rack. Now they not only act as shock absorbers, but also
the role of the elastic element. Truck with a rack requires neither
springs nor springs or torsion bars. It's great to facilitate
construction. The characteristics of such hydropneumatic struts can
change from the cab, varying clearance, stiffness, suspension travel,
and even tilt the car to the left and right or forward and backward.
These racks fit well in the design of the vehicle with independent wheel
suspension, and this rover is not facing diagonal display wheels in
difficult road conditions. Hydropneumatic front of the new generation is
installed in their equipment vendors such as Ginaf and Terberg. While
timid these racks offer manufacturers of trailers on the suspension
trailers. Most likely, this design will be further spread and more
widely used.
