Technology, this paper combines the LTM series all-terrain lift introduced by Xuzhou Construction Machinery Group Company from Liebherr, Germany.
Taking the engine as an example, the structure, principle and characteristics of the hydro-pneumatic suspension system are briefly introduced.
Keywords: structure principle of hydro-pneumatic suspension
1 suspension overview
Suspension refers to all the connecting devices between the frame and the axle that transmit force, and generally consists of elastic elements, shock absorbers and guides.
The structure consists of three parts, and its function is to add vertical reaction force (supporting force) and longitudinal reaction force (traction force and braking force) to the wheel.
Power) and lateral reaction, as well as the torque generated by these reactions, are transmitted to the frame according to people's predetermined purpose, thus ensuring the correctness of the car.
Always driving. Suspension can be divided into passive suspension and semi-active suspension according to whether the performance of suspension is controlled during vehicle driving.
Frame and active suspension are three basic types. A suspension that does not need input energy for control is called a passive suspension; Input a small amount of energy
Controllable damping suspension with adjustable damping coefficient is called semi-active suspension; A controllable suspension that adjusts the control force by inputting external energy.
This is called active suspension. Of course, some documents do not strictly distinguish the boundary between semi-active suspension and active suspension. Think that as long as there is external
When energy changes the dynamic characteristics, the suspension system is called "active". Passive suspension is the earliest and most widely used.
A kind of suspension, after more than 100 years of development and continuous improvement, the design and manufacture of passive suspension is relatively mature, and its cost is relatively high.
Although it is cheap, once the elastic elements and shock absorbers of the passive suspension are installed on the vehicle, the performance of the suspension is fixed and cannot be changed.
Exert control; Semi-active suspension and active suspension are the research hotspots in the field of ride comfort dynamics, and semi-active suspension and active suspension are adopted.
After suspension, the ride comfort of the vehicle is indeed improved, but compared with passive suspension, it has high cost and poor reliability and is only used for
High-end cars, racing cars and important heavy vehicles.
2 Characteristics and application status of hydro-pneumatic suspension
Hydro-pneumatic suspension belongs to passive suspension, but hydro-pneumatic suspension has the structure type of active suspension, so only active suspension can
Some functions and performance of. The 1992 LTM system introduced by Xuzhou Construction Machinery Group Co., Ltd. from Liebherr, Germany.
The all-terrain truck crane and QAY25 all-terrain truck crane designed and produced by Xuzhou Heavy Machinery Factory in 2002 are listed.
This is the hydro-pneumatic suspension. The so-called oil-gas suspension means that oil is used to transmit pressure and inert gas (usually nitrogen) is used as elastic medium.
The throttle hole and one-way valve in the suspension cylinder are one of the shock absorber components in the suspension. Figure 1 shows the oil and gas of LTM 1032 crane.
Shape connection diagram between suspension, frame and axle.
2. 1 Characteristics of hydro-pneumatic suspension
Nonlinear stiffness. The stiffness of passive suspension is basically unchanged because the stiffness of elastic elements is mostly linear, so
The natural vibration frequency f of the frame changes with the change of the frame mass m; However, in the hydro-pneumatic suspension, the stiffness of elastic elements is low.
It is nonlinear and gradually increases (decreases), so the vibration frequency of the car body can not follow the car body through parameter optimization design.
Quality changes or little changes.
B unit energy storage ratio is large. Under the condition of nitrogen inflation pressure of 6Mpa, the unit weight energy storage of oil-gas spring is leaf spring.
Energy storage per unit weight is 3500 times, which is beneficial to reduce the mass and structural size of suspension.
The height of the car body can be adjusted freely. By adjusting the suspension cylinder synchronously or independently, the height of the frame can be up and down, up and down or up and down.
Left and right lifting is very important to improve the passing performance and driving performance of vehicles.
D rigid locking. By cutting off the connecting oil path between the oil cylinder and the accumulator and other hydraulic components, the compressibility of oil is reduced.
Point, can make the oil-gas suspension in a rigid state, in this state, the vehicle can bear a large load and can move slowly.
E nonlinear damping. It can quickly suppress the vibration of the frame and has good shock absorption.
2.2 Application fields of hydro-pneumatic suspension
A military vehicle. Such as "Centauri" wheeled armored vehicle produced in Italy and AMX- 10RC wheeled transport aircraft produced in France.
Cars, lithium saw wheeled tanks made in Switzerland, etc.
All-terrain truck crane. For example, the LTM series cranes produced by Liebherr Company in Germany and Grove Company in the United States.
AT series cranes, RK series cranes produced by Japan Iron and Steel Corporation and QAY25 cranes produced by Xuzhou Heavy Machinery Factory.
Machine.
C scraper machinery. For example, the TS-24B self-scraper produced by Caterpillar Company in the United States.
D-wheel excavator. Such as 10 ton wheel excavator produced by Hitachi Construction Machinery Company.
E mining dump truck. For example, CAT789 dump truck produced by Caterpillar Company in the United States and VMER90 produced by Volvo Company in Sweden.
SH380 and SH382 dump trucks produced by Shanghai Heavy Truck Factory.
2.3 Present situation of oil and gas suspension technology
Oil-gas suspension technology began with the oil-gas shock absorber invented by Carnaud in the late 1960s, which was first applied in German and German.
Japanese heavy vehicles will be gradually applied to military special vehicles and construction machinery vehicles. Current hydro-pneumatic suspension
There are many types of commercial structures, such as single-chamber oil-gas separation, double-chamber oil-gas separation and oil-gas mixing. On the technical side,
The qualitative and quantitative research abroad is comprehensive, and there are many problems such as how to design structural parameters and how the changes of structural parameters affect oil and gas.
The performance of suspension should be said to have good research results, but because it is the key to structural design, it belongs to the business secret of enterprises.
Close to, so it is difficult to see the relevant information, at best, it is just a simplified mathematical model, simulation and simulation of hydro-pneumatic suspension.