﻿ 油缸缓冲装置结构参数对缓冲性能影响分析
 舰船科学技术  2020, Vol. 42 Issue (2): 132-136 PDF

Analysis of cylinder buffering device′s structure parameters to buffering performance effects
KUANG Quan, ZHANG Zhen-hai, ZHU Shi-jian
College of Naval Architecture and Ocean, Naval University of Engineering, Wuhan 430033, China
Abstract: Open and close noise of the hydraulic cylinder driving mechanism is one of the most important factors that affects the vibration and noise performance of ship mechanical equipment. Adding buffering device can reduce the impact vibration effectively during opening-closing process of driving mechanism. This paper focuses on the buffering device of cylindrical variable—throttling area, then derived functional relationship that buffering cavity pressure and piston velocity changes with piston displacement in which case load was considered. After that, the impacts of different structure parameters: unilateral clearance, diameter at large end of buffering cover, cone length and cone angle on buffering performance was analyzed, optimized design scheme of buffering device was also obtained. The results show that: the unilateral clearance is the most influential factors of buffering performance, secondly are diameter at large end of buffering cover and cone length, cone angle has the least influence on buffering performance. After optimized design, the piston velocity near the stroke end point has reduced 98%, this can reduce open and close noise of hydraulic cylinder driving mechanism effectively.
Key words: buffering device     load     structure parameters     buffering performance     vibration and noise
0 引　言

1 缓冲装置数学模型

 图 1 缓冲装置结构简图 Fig. 1 Structure diagram of buffering device

${P_1}$ 为进油压力， ${A_1}$ 为进油压力作用面积， ${A_1} = \dfrac{{\text{π}}}{4}({D^2} - {d^2})$ ${P_2}$ 为缓冲腔压力； ${A_2}$ 为缓冲腔压力作用面积， ${A_2} = \dfrac{{\text{π}}}{4}({D^2} - D_1^2)$ 。式中： $D$ 为液压缸内径；d为活塞杆直径； ${D_1}$ 为缓冲套大端直径。假定油液为不可压缩流体，流动状态为紊流，密封件摩擦阻力相对于惯性力可以忽略不计。以活塞为分析对象，进行受力分析如下：

 ${p_1}{A_1} - {p_2}{A_2} - F = ma {\text{。}}$ (1)

 $Q = {v_x}{A_2} {\text{。}}$ (2)

 $Q = {C_q}A\sqrt {\frac{{2\left| {\Delta p} \right|}}{\rho }} {\text{。}}$ (3)

 $\left| {\Delta p} \right| = \frac{{{Q^2}\rho }}{{2{C_q}^2{A^2}}} = \frac{{{{({v_x}{A_2})}^2}\rho }}{{2{C_q}^2{A^2}}} {\text{。}}$ (4)

 $\begin{array}{l} { A} = \left[ {3\left[ \begin{array}{l} 0.004\;36D_1^2\arccos \left[ {1 - \dfrac{{{L_2}\tan \alpha }}{{{{{D_1}}}/{2}}}} \right] - \\ \dfrac{{{D_1}}}{2}\sin \left[ {\arccos \left[ {1 - \dfrac{{{L_2}\tan \alpha }}{{{{{D_1}}}/{2}}}} \right]} \right] \times \\ \left(\dfrac{{{D_1}}}{2} - {L_2}\tan \alpha \right) \\ \end{array} \right] + {A_3}} \right] \times {10^{ - 6}} {\text{。}} \end{array}$ (5)

1）从缓冲腔压力开始形成到进油压力 ${p_1}$ 达到溢流阀开启压力 ${p_{1\max }}$ 为止，这个过程活塞做匀速运动， ${v_x} = {v_0}$ 。设进油压力 ${p_1}$ 刚好达到溢流阀开启压力 ${p_{1\max }}$ 时，缓冲腔压力为 ${p_{22}}$ ，则 ${p_{22}} = \dfrac{{{p_{1\max }}{A_1} - F}}{{{A_2}}}$ ，与式（4）、式（5）联立可以求出此时对应的 ${L_x}$ ，取为 ${L_{x0}}$ 。根据式（4）得第1阶段缓冲腔压力变化方程如下：

 ${p_2} = \frac{{A_2^2\rho v_0^2}}{{2{C_q}^2{A^2}}} {\text{。}}$ (6)

2）从进油压力 ${p_1}$ 达到溢流阀开启压力 ${p_{1\max }}$ 开始，到缓冲结束，这个过程活塞做变减速运动，加速度 $a$ 不为定值。假设速度函数连续、可导、可局部线性化，计算时把这一段距离分成若干段非常小的 $\Delta {L_x}$ ，则每个小段内，活塞可近似视为作匀减速运动，其对应的加速度为 ${a_x}$ 。设任意小段起始位置的速度为 ${v_{x - 1}}$ $x \geqslant 1$ ），任意小段结束位置的速度为 ${v_x}$ ，则

 ${v_x} = \sqrt {v_{x - 1}^2 - 2{a_x}\Delta {L_x}} {\text{。}}$ (7)

 ${p_2} = \frac{{A_2^2\rho (v_{x - 1}^2 - 2{a_x}\Delta {L_x})}}{{2{C_q}^2{A^2}}} {\text{，}}$ (8)

 ${a_x} = \frac{{2{C_q}^2{A^2}(F - {p_{1\max }}{A_1}) + A_2^3\rho v_{x - 1}^2}}{{2(A_2^3\rho \Delta {L_x} - {C_q}^2{A^2}m)}} {\text{。}}$ (9)

2 参数对缓冲性能影响分析

 图 2 AMESim仿真模型 Fig. 2 Simulation model of AMESim

2.1 单边间隙

 图 3 不同单边间隙下活塞速度与缓冲腔压力随活塞位移变化曲线 Fig. 3 Curves of buffering cavity pressure and piston velocity changes with piston displacement under different unilateral clearances

2.2 缓冲套大端直径

 图 4 不同缓冲套大端直径下活塞速度与缓冲腔压力随活塞位移变化曲线 Fig. 4 Curves of buffering cavity pressure and piston velocity changes with piston displacement under different diameters at large end of buffering cover
2.3 圆锥段长度

 图 5 不同圆锥段长度下活塞速度与缓冲腔压力随活塞位移变化曲线 Fig. 5 Curves of buffering cavity pressure and piston velocity changes with piston displacement under different cone lengths
2.4 锥角

 图 6 不同锥角下活塞速度与缓冲腔压力随活塞位移变化曲线 Fig. 6 Curves of buffering cavity pressure and piston velocity changes with piston displacement under different cone angles
3 参数优化与缓冲性能分析

 图 7 活塞速度与缓冲腔压力随活塞位移 Fig. 7 Curves of buffering cavity pressure and piston velocity changes with piston displacement

4 结　语

1）单边间隙对缓冲腔压力和活塞速度的影响最大，缓冲套大端直径、锥角的影响次之，圆锥段长度对缓冲性能的影响最小。

2）有缓冲与无缓冲相比，活塞在到达行程终点前的速度（盖板与止挡板的撞击速度）下降约为98%，缓冲过程较为平缓，没有出现较大的液压冲击。

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