Displacement magnification (DM) is one of the key indicators to measure the performance of a micromanipulator. Based on the principle of triangle amplification, a series of three-stage displacement amplification (DA) micromanipulators is designed in this paper, which is driven by a piezoelectric actuator. The mechanism is composed of a compound rhombus mechanism, a bridge mechanism and two parallelogram mechanisms. The compound rhombus mechanism is located at the front end and has high stiffness characteristics. The bridge mechanism is located at the back end and is connected to the parallelogram mechanism to realize the parallel output of the clamping end. The DM model of the mechanism is established. On this basis, the structural size optimization design is carried out. With the goal of maximizing the DM, the key geometric parameters such as the thickness and length of the hinge and the section size of the key rod are selected as the design variables. Considering the constraints of material strength and input stiffness, the parameters of the micromanipulator are optimized. The correctness of the optimization method is verified by finite element simulation and experimental test. The results show that the DM of the optimized micromanipulator is significantly improved under the premise of maintaining sufficient stiffness, which can effectively guide the performance improvement and structural design of the micromanipulator.

To address the mid-to-high frequency howling noise issue in the suspension control pump of a certain vehicle model and improve its NVH (Noise, Vibration, and Harshness) performance, a systematic study on noise mechanism analysis and optimization design was conducted based on a combination of experimental testing and computational fluid dynamics (CFD) simulation. Standardized tests in an anechoic chamber identified the core noise characteristic as howling caused by mid-to-high frequency “double-peak” coupling, with the original prototype’s noise level measured at 63.6 ∼ 64.7 dBA. CFD simulations revealed the multi-faceted coupled noise mechanism, including uneven flow field pressure fluctuations, vortex generation in pipelines, gear meshing resonance, and the superposition of motor and gear frequencies. Finally, an optimized structural solution for the pressure relief zone was proposed. Through simulation and experimental validation, the optimized low-pressure oil cavity pressure fluctuation amplitude was reduced by 28%, while the high-pressure oil cavity’s fluctuation amplitude decreased by 21%, lowering the noise level to 53.4 ∼ 54.1 dBA. The findings indicate that the coupled effect of hydrodynamic excitation imbalance and frequency superposition is the primary cause of howling noise. Flow field optimization enables fundamental noise control, providing a comprehensive technical framework for NVH performance enhancement in automotive oil pump components, with significant engineering application value.