Structure of air spring

Air spring is a rubber metal composite which is made of rubber, cord and steel wire circle, which is bonded together by vulcanization process.

Rubber air bag is an important part of air spring, which is usually vulcanized (crosslinked) by inner rubber layer, outer rubber layer, cord layer and formed steel ring. According to the deformation mode of the rubber airbag, the structure of the air spring of commercial vehicle can be divided into two types: the bladder type and the membrane type.

1. Bladder air spring

The bladder air spring is a lantern shaped structure, and its curved bladder is composed of one or several segments in series, which are called single curved, double curved or multi curved bladder air spring respectively. The elastic deformation of the air spring is mainly obtained by the bending of the rubber air bag, which is composed of the rubber air bag, the auxiliary air chamber, the upper cover plate, the clamping ring, the buffer and so on.

2. Membrane air spring

Membrane air spring is a cylindrical structure, through the balloon curl to obtain elastic deformation, in order to achieve the overall expansion and contraction. The utility model is composed of a rubber air bag, an upper cover plate, a buffer block and a piston base. Sometimes the hollow inner cavity of the piston base also acts as an auxiliary air chamber.

Matters needing attention in installation and use of air spring

1. Working pressure

In order to avoid early damage of air spring due to too low or too high air pressure, the working air pressure of air spring should be within a strict range.

If the hoop seal is used for the air spring, the general inflation pressure shall not be less than 0.07MPa; if the rim clamp or pressure self seal is used, the inflation pressure shall not be less than 0.1MPa

Generally, the design pressure of air spring is one-third of the burst pressure. For better working environment, the design pressure of air spring can reach one-half of the burst pressure.

2. Working distance

The allowable stroke of the air spring is listed in the performance parameter table of each air spring. In order to ensure the service life of the air spring, the air spring is not allowed to exceed the allowable stroke of the air spring in use.

3. Installation conditions

When the air spring is installed, the upper cover plate and the lower cover plate or the base plate should have the same center line as far as possible to reduce the offset and tilt of the center line of the air spring. At the same time, it should also ensure that there is enough installation space, the air spring should not have friction with any parts, and should not have movement interference with any parts in the process of use, and should prevent the impact of hard objects.

4. Service conditions

In use, rubber air spring should be kept dry, cool and ventilated as far as possible. It should avoid exposure to the sun. It is forbidden to contact with acid, alkali, oil and other organic lubricants, and keep away from heat sources.

5. Replacement

When the air spring is replaced, it should be replaced according to its model and specification. If the air spring with the same model and specification cannot be obtained, it should be replaced by the air spring with the same performance.

Common faults of air spring

1. Capsule failure

(1) Rubber airbag surface is worn.

The gap between air spring and surrounding parts is insufficient, and it will be worn by friction with other parts of air suspension during operation. When hard objects such as sand or soil are attached outside the piston base of air spring, the reciprocating movement of rubber airbag and hard object friction will cause wear.

When the wear is serious, the rubber airbag will break. If the shock absorber is damaged, the air pipeline or brake system pipeline is loose, it will cause friction caused by interference with rubber airbag, and the surface of rubber airbag will be worn.

(2) There are chemical erosion holes on the surface of rubber airbag.

When the rubber airbag is stuck with grease, oil or gasoline, if it is not cleaned in time, the grease will corrode the surface of the rubber airbag, and chemical erosion holes will appear.

(3) The rubber gasbag was aging and wrinkled.

The rubber air bag is stained with grease and so on, which may lead to premature aging or normal aging.

(4) The rubber air bag is collapsed and cannot bear the load.

Leakage or blockage of air control pipeline; Height control valve failure; The air pressure in the air reservoir is too low to open the pressure protection switch.

2. Upper cover plate failure

(1) The upper cover plate is sunken.

The height of air suspension is too low, and the air spring works under low air pressure for a long time; Height control valve failure; The air pressure in the rubber airbag is too low, and the vehicle is overloaded seriously; The type of air spring used is wrong.

(2) The upper cover plate is raised.

The air suspension height is too high, and the air spring works under abnormal air pressure for a long time; Height control valve failure; The shock absorber is damaged or the model is not correct; The type of air spring used is wrong.

(3) The screws of the upper cover plate are loose and trip.

For the air spring with screw fastening sealing method, due to the different fastening force of the screws around the upper cover during assembly, the screws are not evenly stressed, which will slowly loosen and trip during operation.

3. Throttle valve failure, throttle valve falling off.

For the throttle valve with screw fastening to ensure the relative position between the adjusting seat and the valve sleeve, the screw is easy to loosen in the vibration process, resulting in the loosening and separation of the valve seat and the valve sleeve.

4. Air leakage

(1) The joint of the rubber air bag and the upper cover plate or the piston base is cracked, air leakage or air leakage at the root of the bolt. The air spring works in the range beyond the allowable stretching stroke for a long time;

(2) The air pressure in the rubber air bag is too high and the overload is serious;

(3) The air suspension shock absorber is damaged or the model is wrong;

(4) The eccentric contact of the buffer block results in local wear at the joint of the rubber bag and the upper cover plate edge or the piston base.

(5) In winter, the temperature is too low and the temperature difference is large, which leads to the rupture of the outer surface of the capsule.

Preventive measures to avoid air spring failure

(1) When assembling the air suspension, select the reasonable type of air spring in strict accordance with the technical indicators to prevent the air spring from working under too low or too high air pressure.

(2) During the installation process, ensure that the gap between the air spring and the surrounding parts is reasonable, and ensure that there is no friction between the air spring and other parts.

(3) The outer layer of the rubber capsule is made of high strength rubber material to improve the strength of the outer layer of the air spring capsule.

(4) Avoid chemical and oil substances contacting the surface of air spring rubber bag.

(5) For the sealed air spring with screw fastening, when the upper cover screw is loose or tripped, the screw shall be tightened with screw fastening glue. When the screw is broken, the screw with reliable quality shall be replaced.