Hydro Pneumatic Cylinder Working Principle Pdf 34

Hydraulic pumps are a positive displacement pump whose working principle causes inherent output flow pulsation. Flow pulsation produces pressure pulsation when encountering liquid resistance. Pressure pulsation spreads in the pipeline and causes vibration, noise, damage, and even pipeline rupture and major safety accidents. With the development of airborne hydraulic systems with high pressure, power, and flow rate, the hazards of vibration and noise caused by pressure pulsation are also amplified, severely restricting the application and development of hydraulic systems. In this review paper, the mechanism, harm, and suppression method of pressure pulsation in hydraulic systems are analyzed. Then, the classification and characteristics of pulsation attenuators according to different working principles are described. Furthermore, the critical technology of simulation design, matching method with airborne piston pumps, and preliminary design method of pulsation attenuators are proposed. Finally, the development trend of pulsation attenuators is prospected. This paper provides a reference for the research and application of pressure pulsation attenuators.

As the power component of the hydraulic system, the hydraulic pump mainly includes the gear, impeller, and piston pumps [7], which are parts of the positive displacement pump whose working principle is shown in Figure 1. The piston reciprocates periodically in the pump cylinder to alternately increase and decrease the working volume in the cylinder to complete oil suction and pressure. The working principle of the positive displacement pump determines the flow pulsation of its output with periodic variation [8,9,10]. Figure 2 shows the flow rate characteristics of the nine pistons of the piston pump [11].

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Figure 15 presents single expansion chamber type (also called C-type), series type, K-type, and insert-pipe type expansion chamber type pulsation attenuators. When hydraulic oil with pulsation characteristics enters the chamber, the fluid suddenly expands and then compresses due to the action of the sudden expansion pipe and the compressibility of hydraulic oil. This process releases the pulsation energy of the fluid and reduces the pressure pulsation [11]. The working principle of this type of attenuator indicates that its attenuation to low-frequency pulsation is not obvious, but it has a good attenuation effect to high-frequency pulsation [6] and is small and easy to install. K-type and other pulsation attenuators with an insert-pipe have a better attenuation effect than the other attenuator types [62, 63].

Regeneration principles

Applying fluid flow to both ports of a single-rod cylinder makes it extend -- or at least try to extend. Because areas on opposite sides of the piston are unequal, the cap end of the cylinder always has more force than the rod side.

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