Comprehensive Review Comparing the Development and Challenges in the Energy Performance of Pneumatic and Hydropneumatic Suspension Systems

The purpose of this review is to comprehensively compare the developments and challenges in the energy performance of unconventional pneumatic suspension (PS) and hydropneumatic suspension (HPS), which have special applications in passenger cars, trucks, military vehicles and agricultural equipment. The main differences between PS and HPS, as well as their advantages and disadvantages, are presented. The PS system is discussed along with its principle of operation, advances in development, principle of operation of air springs, their models, characteristics, vibration isolation, and simulation models. The HPS system is discussed, along with its operational principles, progress in development, models, and characteristics. This review also discusses new trends in HPS development, such as the effect of a pressure fluctuation damper (PFD) placed in a hydraulic cylinder on the damping performance index (DPI) of an HPS under off-road driving conditions. It highlights innovative solutions that can be expected in the future in PS and HPS systems, with the expectations of drivers and passengers. The review focused on trends and challenges in PS and HPS development, such as integration with electronics, smart solutions, customized solutions, emphasis on compliance with ecological and environmental requirements, and applications in electric vehicles (EVs) and autonomous vehicles (AVs).