Technical Article

How to design the cylinder buffer device

In the hydraulic system, a hydraulic cylinder is used to drive objects with a certain mass. When the hydraulic cylinder moves to the end of the stroke, it has a large kinetic energy. If there is no deceleration treatment, the hydraulic cylinder piston and the cylinder head will mechanically collide, causing impact and noise. In order to alleviate and prevent such things from happening, a deceleration device can be installed in the hydraulic circuit or a buffer device can be installed in the cylinder.

Structural design principle of high-speed hydraulic cylinder buffer device

When the high-speed hydraulic cylinder is working, the piston terminal speed can reach more than 5m/s. If it directly collides with the end cover, under the action of inertial force and hydraulic pressure, not only the end cover will be damaged, but also a large impact load will be generated. The system has an adverse effect.

When the piston rod reaches the end of the stroke, the stop is stopped by the end of the hydraulic cylinder, and the piston, the piston rod, and the fixed nut continue to move forward. At this time, the piston and the stop form a throttle gap, between the piston and the stop. The pressure in the cavity increases, which opposes the inertial force of the piston and the hydraulic pressure acting on the left end of the piston, so as to achieve the purpose of buffering.

Structural design principle of large cylinder diameter and long stroke hydraulic cylinder buffer device

For horizontally installed large-bore and long-stroke hydraulic cylinders, due to the huge weight of the piston rod and piston, machining errors and installation errors of parts, the hydraulic cylinder is easy to cause rapid wear of the guiding part near the load-bearing side during operation. This leads to eccentricity of the guide element. These reactions on the buffer element, that is, the excessive coaxiality between the buffer ring and the buffer hole will cause operating difficulties or mechanical failure.

After the hydraulic cylinder enters the buffer stroke, the spring seat is pressed on the buffer step surface at the bottom of the cylinder under the action of the spring to form a mating surface. The two mating surfaces work together to convert mechanical energy into hydraulic energy, and the sealed oil passes through the small hole of the throttle valve slowly flows out of the oil discharge chamber. Due to the damping effect of the throttle orifice, the sealed oil is slowly released, thereby realizing the slow release of hydraulic energy, and then realizing the process of decelerating and braking the piston and the piston rod. Since the mating surface will not be affected by the coaxiality of the guide element and mechanical errors, the influence of eccentricity on the buffering process is eliminated.