DOI: 10.1088/1361-665X/acfc0b

Abstract

The piezoelectric hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by a piezoelectric stack connected to a hydraulic cylinder. For this type of piezoelectric actuator, the inertial force caused by the flow pulsation of the liquid will inhibit the movement of the piezoelectric vibrator and reduce its output performance. To solve these issues, two tubes were embedded into the piezoelectric-hydraulic hybrid actuation system for the first time to act as mechanical band-stop filters by interfering with the propagation of acoustic waves. The acoustic power transmission loss of the tube is derived from the one-dimensional wave equation. According to the experimental results, when the excitation frequency is close to the optimal operating frequency corresponding to the tubes, the liquid pulsation rate is reduced, the influence of inertial force on the actuator is weakened, and the output performance is relatively significantly improved. This strategy finally leads to a maximum no-load velocity of 153.5 mm/s and a maximum blocking force of 261.5 N for the hybrid actuator with 300 mm tubes; the maximum no-load velocity and blocking force of the hybrid actuator with 500 mm tubes are 94.45 mm/s and 230 N, respectively. Furthermore, this strategy can be used in other electrohydraulic actuators to enhance their capabilities.

文章摘要

压电液压致动器是一种混合装置，由连接到液压缸的压电堆驱动的液压泵组成。对于这类压电致动器来说，由液体的流量脉动引起的惯性力会抑制压电振子的运动，降低其输出性能。为了解决这些问题，首次将两根管道嵌入压电液压混合驱动系统中，使其干扰声波的传播来充当机械带阻滤波器。管道的声功率传输损耗由一维波动方程导出。实验结果表明，当激振频率接近该管道对应的最佳工作频率时，液体脉动率减小了，惯性力对致动器的影响减弱了，致动器的输出性能得到较为显著的改善。该策略最终使得具有300 mm管道长度的混合致动器的最大空载速度为153.5 mm/s，最大阻挡力为261.5 N；具有300 mm管道长度的混合致动器的最大空载速度和阻挡力分别为94.45 mm/s和230 N。此外，该策略还可用于其它电静液致动器以增强其功能。

图片摘要

  图中显示了这三种混合致动器的速度和效率与负载的关系图，激励电压为700 Vp-p，偏置压强为2 MPa；具有300 mm或500 mm波长管的混合致动器的激励频率分别为742 Hz和455 Hz。在外部负载条件下，带有四分之一波长管的混合致动器的速度大于没有四分之一波长管的混合致动器的速度。当负载增加时，这三种混合致动器的速度都减小，而这两种新型混合致动器的效率先增加然后减少。具有300 mm波长管的混合致动器在40 N负载下效率最高，为12.44%，其对应的速度为94.1 mm/s。当负载为60 N时，具有500 mm波长管的混合致动器具有6.28%的最高效率，此时的速度为39.1 mm/s。 值得一提的是，当施加到压电堆上的电压进一步增加时，混合执行器的性能可以进一步提高。

(a)                                                            (b)

Fig. 1. Plot of the velocity and efficiency versus load. (a) For the hybrid actuators with 300 mm wavelength tubes and without quarter-wavelength tubes. (b) For the hybrid actuators with 500 mm wavelength tubes and without quarter-wavelength tubes.

亮点:

1.混合致动器系统中嵌入的四分之一波长管通过干扰声波的传播成功地发挥了机械带阻滤波器的作用，有效地减少了液体的脉动，减弱了惯性力对混合执行器的影响，提高了其输出性能。

2.四分之一波长管的声功率传输损耗由一维波动方程导出，有助于读者理解其基本机理。

3.该策略为抑制高频流量脉动奠定了良好的基础。

4.所提出的策略为提高其它电静液致动器的输出性提供了参考。