空氣彈簧的結構及要點分析StructuRE and key points analysis of air spring

現如今，空氣彈簧的使用範圍變得越來越廣，尤其是在許多震動設備上，空氣彈簧成為了必不可少的設備之一。因而，探討空氣彈簧在震動設備上的應用十分有必要，這也是提升應用效果的重要工作之一。

空氣彈簧的結構形式及特點

空氣彈簧是利用橡膠氣囊裏面的壓縮空氣的反作用力當做彈性恢複力的一種彈性元件。空氣彈簧憑借其良好的減振和隔振性能而被大量應用於汽車、鐵道車輛、艦船、航空、工業等領域的動力機械、電子設備、儀器儀表、化工機械等設備。

1、空氣彈簧結構形式

空氣彈簧是在柔性的橡膠囊中充入有一定壓力的空氣，利用空氣的可壓縮性實現彈性功效的非金屬彈簧。空氣彈簧主要分為囊式空氣彈簧和膜式空氣彈簧兩類。

在現如今機械設計過程中，空氣彈簧早已像齒輪一樣，能夠當做標準件對待，按照載荷的重量和幾何安裝尺寸就能夠選擇相對應的空氣彈簧。

2、空氣彈簧的特點

(1)空氣彈簧的彈性系數是可變的，隨著所加載荷的增加，彈性系數也隨之增大。空氣彈簧能夠設計各種以滿足各種性能要求的效果曲線，是因為空氣彈簧具有非線性的效果。

(2)空氣彈簧橡膠本體較為輕，空氣的質量也十分小，空氣彈簧的重量大部分來自上蓋和下蓋，不像鋼彈簧，金屬質量較為重。

(3)空氣彈簧的承載力可按照橡膠氣囊內充氣壓力的大小進行調節，則針對同一空氣彈簧，可以通過調節充氣壓力的大小來滿足不同的承載力需要。

(4)由於空氣彈簧以空氣為彈性介質，當壓縮時，內摩擦小，因而隔振效果較為好。此外，空氣彈簧有很好的消除噪音能力，是因為空氣和橡膠傳播聲音的能力都較為弱。

(5)空氣彈簧抗疲勞能力較為強，實驗表明:針對通常情況下的鋼板彈簧可承受的應力循環數為50萬至60萬次，而一般空氣彈簧能夠可達到300萬次左右，高質量空氣彈簧可承受的應力循環數能夠可達到500萬次以上。因而空氣彈簧在抵抗應變這方面功效突出。

(6)但製造空氣彈簧工藝要求高且繁雜，因而成本較高。

空氣彈簧的控製系統

空氣彈簧的控製系統伴隨著其他相關的高新科技的發展發生了兩次變革，經曆了三個發展階段:機械控製，電子控製和智能控製。但不論哪種控製系統都大體上包含三個子模塊:空氣供給系統(氣源)，控製元器件(包括軟件)，安全裝置(保證空氣彈簧的正常運行)。三種控製系統的氣源和安全裝置伴隨著控製元器件的不同會有相應的差異，但是它們最根本的差異在於控製元器件，對於機械控製系統來講，它的控製元器件主要是高度控製閥，使用其自動地對空氣彈簧實現充氣和排氣，實現空氣彈簧高度的控製；電控系統較機械控製系統前進了一大步，是一個質的飛躍，這也是運用電子控製器(ECU)采集各種類型傳感器傳來的信號，對信號實現分析後將控製信號發送給執行器(主要是各種電磁閥)，從而實現對空氣彈簧的控製；智能控製系統是在電控系統的基礎之上依靠現如今自動控製理論發展起來的，它主要是對ECU的軟件部份實現了改進，不但可以控製空氣彈簧的高度和剛度，而且可以使用模糊神經網絡等控製技術可以實現空氣彈簧非線性特性的控製。

幾個影響空氣彈簧因素分析

氣室與附加氣室容積的比例，空氣彈簧形狀、材料、尺寸，以及氣室與附加氣室之間的節流孔的大小，對系統剛度和固有頻率都會有相應的影響。

1、簧囊橡膠材料本身剛度對系統一階諧振頻率的影響。實驗證明，橡膠氣囊材料本身剛度對空氣彈簧剛度影響極大，這也是導緻空氣彈簧剛度理論值與實驗值差異比較大的原因。橡膠氣囊材料剛度越大，空氣彈簧的剛度就越大，其一階諧振頻率越高，其結果提高了系統工作時最小工作頻率。因而，橡膠氣囊隔震系統應當減小材料剛度，減小自振頻率，使得空氣彈簧隔振器的承載能力留出足夠的餘量情況下，系統最小工作頻率盡可能低。

2、振動台橫向振動時，簧囊橡膠材料剛度要大上許多。橡膠空氣彈簧的本體結構柔軟，因而具有軸向、橫向和旋轉向的綜合隔震作用。機械式振動台橫向振動時，簧囊橡膠材料剛度要大上許多。

3、在空氣彈簧和附加氣室之間設一節流孔，當空氣流過節流孔時，因為阻力而吸收一小部分振動能量，進而起到減振阻尼的作用。除去影響系統的剛度和固有頻率之外，節流孔的大小主要影響了系統的阻尼。

系統剛度隨節流孔開度增大而減小，阻尼隨節流孔的增大先增大後減小，附加氣室容積的增大能使系統剛度減小並使阻尼比增大，激勵頻率的增大會增大系統剛度並減小系統阻尼比，靜載荷的變化對系統振動特性影響不大。

Nowadays, the use of air spring has become more and more widely, ESPECially in many vibration equipment, air spring has become one of the essential equipment. Therefore, it is necessary to explore the application of air spring in vibration equipment, which is also one of the important work to improve the application effect.

Structure and characteristics of air spring

Air spring is an elastic element which uses the reaction force of compressed air in rubber airbag as elastic restoring force. Air spring is widely used in power machinery, electronic equipment, instrumentation, chemical machinery and other equipment in the fields of automobile, railway vehicle, ship, aviation, industry and so on.

1. Air spring structure

Air spring is a kind of non-metallic spring which is filled with air with certain pressure in flexible rubber capsule, which makes use of the compressibility of air to realize elastic effect. Air spring is mainly divided into two types: bag type air spring and membrane type air spring.

In today's mechanical design process, air spring has long been like a gear, can be treated as a standard part, according to the weight of the load and geometric installation dimensions can choose the corresponding air spring.

2. Characteristics of air spring

(1) The elastic coefficient of air spring is variable, and the elastic coefficient increases with the increase of load. Air spring can design various effect curves to meet various performance requirements because of its nonlinear effect.

(2) The rubber body of the air spring is lighter, and the air mass is also very small. Most of the weight of the air spring comes from the upper cover and the lower cover. Unlike the steel spring, the metal mass is heavier.

(3) The bearing capacity of the air spring can be adjusted according to the inflation pressure in the rubber airbag. For the same air spring, the different bearing capacity needs can be met by adjusting the inflation pressure.

(4) Because the air spring takes air as elastic medium, when compressed, the internal friction is small, so the vibration isolation effect is better. In addition, the air spring has a good ability to eliminate noise, because the ability of air and rubber to transmit sound is relatively weak.

(5) The experimental results show that the number of stress cycles that the leaf spring can bear is 500000 to 600000 times, while the general air spring can reach about 3 million times, and the high-quality air spring can bear more than 5 million cycles. Therefore, the effect of air spring in resisting strain is outstanding.

(6) However, the manufacturing process of air spring requires high and complicated technology, so the cost is high.

Control system of air spring

With the development of other related high-tech, the control system of air spring has undergone two changes and experienced three development stages: mechanical control, electronic control and intelligent control. However, no matter what kind of control system, it generally includes three sub modules: air supply system (air source), control components (including software), and safety device (to ensure the normal operation of air spring). The air source and safety device of the three control systems will have corresponding differences along with the difference of control components, but their most fundamental difference lies in the control components. For the mechanical control system, its control component is mainly the height control valve, which can automatically inflate and exhaust the air spring to realize the control of air spring height; the electronic control system is more mechanical The control system has made a big step forward, which is a qualitative leap. It is also the use of electronic controller (ECU) to collect the signals from various types of sensors, and send the control signals to the actuator (mainly various solenoid valves) after the signal is analyzed, so as to realize the control of the air spring; the intelligent control system is based on the electronic control system and relies on the present automatic control theory It can not only control the height and stiffness of the air spring, but also control the nonlinear characteristics of the air spring by using fuzzy neural network and other control technologies.

Analysis of several factors affecting air spring

The ratio of the volume of the air chamber to the additional chamber, the shape, material and size of the air spring, as well as the size of the throttle hole between the air chamber and the additional air chamber, have corresponding effects on the system stiffness and natural frequency.

1. The influence of the stiffness of the rubber material on the first-order resonance frequency of the system. The experimental results show that the stiffness of the rubber airbag material has a great influence on the stiffness of the air spring, which is also the reason for the large difference between the theoretical value and the experimental value of the air spring stiffness. The greater the material stiffness of the rubber airbag, the greater the stiffness of the air spring, and the higher the first-order resonance frequency, which results in the increase of the minimum working frequency of the system. Therefore, the rubber air bag isolation system should reduce the material stiffness and natural vibration frequency, so that the minimum working frequency of the system can be as low as possible when the bearing capacity of the air spring isolator is sufficient.

2. When the shaking table vibrates laterally, the stiffness of the spring bag rubber material is much larger. Because of its soft structure, rubber air spring has comprehensive isolation effect in axial, transverse and rotational directions. When the mechanical shaking table vibrates laterally, the stiffness of the spring bag rubber material is much larger.

3. A throttle hole is set between the air spring and the additional air chamber. When the air flows through the orifice, it absorbs a small part of the vibration energy due to the resistance, thus playing the role of vibration damping. In addition to affecting the stiffness and natural frequency of the system, the size of the orifice mainly affects the damping of the system.

The system stiffness decreases with the increase of orifice opening,