The working principle of the accumulator of pump truck, and its basic fault judgment and treatment

Accumulator, as the name implies, is an appliance or device that stores energy. It is generally used in hydraulic and pneumatic circuits to store hydraulic or pneumatic energy. At the same time, when it is working, it instantly releases the stored hydraulic energy, thereby allowing a certain These actuators get a higher pressure or flow in an instant, allowing them to produce a certain action in an instant.

On the pump truck, the accumulator is used to control the swing of the S tube. When the piston of the concrete cylinder changes direction, the pendulum cylinder obtains the hydraulic energy released from the accumulator instantaneously, so that the S tube instantly connects with the concrete cylinder at the other end. , So as to achieve the continuity of pumping.

The above figure is the hydraulic principle diagram of the swing cylinder of the pump truck. When the electromagnetic directional valve is in the neutral position, the pressure oil generated by the oil pump is supplied to the accumulator. The longer the time, the greater the pressure oil pressure of the accumulator, which passes through the hydraulic control sequence valve. Realize pressure regulation.

The solenoid coil at one end of the electromagnetic reversing valve generates magnetic force, which pushes the spool to move, thereby realizing the reversal of the oil circuit. The pressure oil is connected with the pendulum cylinder. Whether it is from the rodless cavity or the rod cavity of the pendulum cylinder, the piston Will be pushed instantly, so that the movement of the S tube can be achieved in one step. After the swing cylinder action is completed, the solenoid coil is de-energized, the oil circuit is cut off, and the oil pump continues to supply oil to the accumulator to prepare for the next swing.

1.Classification of accumulators

According to different working methods, accumulators can be divided into spring type, heavy hammer type and gas-filled type. The pump truck uses gas-filled accumulators.

2.Internal structure and principle of inflatable accumulator

There is a bladder for storing inert gas inside the inflatable accumulator. Under normal circumstances, nitrogen with a pressure of 10Mpa needs to be flushed into the bladder, hence the name inflatable accumulator.

The working process of the inflatable accumulator is divided into two processes: pressure accumulation and pressure release. Specifically, when working, the pressure oil enters the accumulator from the lowermost poppet valve. When the pressure is greater than the air pressure in the bladder, the bladder Compressed by pressure oil, hydraulic energy is stored as gas internal energy in this way. This is because gas is compressible. The smaller its volume, the greater the stored gas energy. When the pressure outside the system is lower than the internal pressure of the accumulator, the oil in the accumulator flows to the outside under the action of high-pressure gas. This refers to the pressure oil flowing to the swing cylinder, which instantly releases a large amount of energy to obtain a faster speed.

3.Troubleshooting common faults of accumulators

There is a problem with the accumulator. The most intuitive performance is to see how fast the swing cylinder or S tube moves. Under normal circumstances, the commutation of the S tube is completed instantaneously. If the commutation speed of the S tube is slow, or the swing cylinder is weak, a large part of the reason is related to the accumulator.

First of all, you can see how much the pressure drop of the reversing pressure gauge is. Before and after work, it is normal for the pressure difference to be between 5-7Mpa. If the pressure difference value is less than 5Mpa, it means that the accumulator has not played the role of accumulating energy. Next, it is natural to check the air pressure in the accumulator bladder.

A sharp object can be used to top the charging valve of the accumulator. If it is easily opened, or the sound of airflow and oil mist is not heard after opening, it means that the pressure of the accumulator is not enough. There are also two situations here, one is that the bladder releases pressure to the outside through the inflation valve, and the other is that the pressure of the bladder is damaged and the pressure is leaked internally. It is also very simple to check whether the leakage is internal or external. Inflate the bladder directly. The swing cylinder works normally within a short period of time. If the swing is weak after a period of time, it is likely to be an external leakage. If the pressure returns within a short period of time It is not enough. It is very likely that the skin bladder is damaged and the air pressure leaks. At this time, the bladder needs to be replaced.

Precautions for replacing the bladder:

  1. Before disassembling the accumulator, the pressure of the distribution system and the air pressure in the bladder must be vented
  2. Before assembling the accumulator, the inside and the bladder of the accumulator need to be cleaned with hydraulic oil. Do not wear gloves during the entire installation process.