Main parameters and common problems of hydraulic pump
Main parameters and common problems of hydraulic pump
(5) The way to control the vibration and noise of the hydraulic pump is that the noise types of the hydraulic pump mainly include mechanical noise and fluid noise. Therefore, from the perspective of selection, use and maintenance, the main ways to control the vibration and noise of the hydraulic pump are as follows.
① Low noise hydraulic pump and prime mover are preferred.
② In order to reduce the mechanical vibration and noise, it is necessary to improve the machining and installation accuracy of the related parts of the hydraulic pump set.
③ When the hydraulic pump set is placed on the top cover of the oil tank, vibration isolation measures (such as adding rubber vibration isolation pad) should be taken under the base of the pump set to cut off the transmission channel of mechanical noise and prevent oil tank vibration.
④ If the installation space is allowed, the non upper hydraulic pump station should be considered, and the pump set and the oil tank should be placed separately (Fig. T), so as to isolate the influence of the vibration of the pump set on the oil tank.
⑤ The inlet and outlet of the hydraulic pump are connected by hose (Fig. T) to cut off the mechanical vibration of the pump.
⑥ Increase the structural rigidity of the oil tank, such as setting stiffeners, so that it is not easy to be excited; on the premise of ensuring heat dissipation, strive to reduce the surface area of the oil tank to reduce its radiation noise.
⑦ Reasonable design and installation of pipeline. On the premise of meeting the use requirements, by changing the length of the pipeline to avoid the external excitation frequency and resonance point; configure a certain number of pipe clamps to improve the connection stiffness of the pipeline to prevent its vibration; if necessary, the viscoelastic damping material can be wound on the outer wall of the pipeline to absorb the vibration energy of the pipeline and reduce the amplitude through the internal friction of the material, so as to reduce the intensity of sound radiation.
⑧ The specific measures to prevent the fluid noise caused by the vibration caused by the pressure and flow changes in the hydraulic system are as follows.
a. Hydraulic components and pipe joints shall be well sealed to prevent air from entering the system and local low pressure in the system, so as to reduce the noise caused by cavitation. Therefore, the speed of the hydraulic pump should not be too high. Under the same power, the large flow pump should be selected to work at low speed, so as to avoid the local low pressure area caused by the high flow rate and the noise caused by the air precipitation in the oil. Improve and improve the oil absorption performance of the hydraulic pump, such as the oil viscosity should not be too high, the resistance loss of the oil absorption filter should be small; reasonable piping [as shown in Figure U (a), most of the oil of the double pump flows through the large flow pump (low pressure), while the small flow pump is easy to produce cavitation noise due to insufficient oil absorption, so the piping in Figure U (b) is more reasonable], and the oil absorption pipe of the pump should be short and thick. The hydraulic pump is installed below the oil tank or the supercharged oil tank is adopted. The pressure difference between the inlet and outlet of the control valve should not be too large. Generally, the pressure ratio between the inlet and outlet should not be greater than 3.5.
b. Prevent hydraulic shock noise. When the system has hydraulic shock, it will be accompanied by violent noise. Therefore, we should try to prevent the system from hydraulic shock. For example, slow down the opening and closing speed of hydraulic system valve; slow down the braking speed of actuator; prevent load mutation, etc.
c. Prevent pressure pulsating noise. The periodic flow pulsation of hydraulic pump is the main source of pressure pulsation. Because of the pressure pulsation, the components and pipes in the system will vibrate periodically, and the noise will be excited. Especially when the pulsating frequency is close to or coincides with the natural frequency of the pipe system, the resonance of the system will be excited and the noise will increase. The natural frequency of the piping itself can be adjusted by reasonably determining the position of the pipe clamp to avoid resonance pipe length.
d. The accumulator or Helmholtz resonance muffler is set near the hydraulic pump.
e. Limit noise propagation. When the above-mentioned noise control measures fail to achieve the expected effect, the sound insulation, sound absorption and other technical measures can be taken to limit the transmission of noise. For example, cover the hydraulic station with sound insulation cover. The acoustic enclosure should be designed according to the user. In the design, structural materials with large sound insulation capacity should be selected (such as placing lead foil and other high-density materials in the middle of the sound insulation board), and the inner surface of the sound insulation cover should have good sound absorption capacity (porous materials such as glass fiber and plastic are commonly used as sound absorption materials). The selected sound insulation structure design scheme (Figure V) should be sound insulation and ventilation and heat dissipation.