Browse Topic: Hydraulic and pneumatic hybrid power

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Pressure-Dependent Nonlinearities of a Compact Hydropneumatic Strut with Integrated Gas–Oil Chamber10-09-01-00081/24/2025
Hydropneumatic Struts (HPS) are widely implemented in automobile, aerospace, and construction industries, mainly for the purpose of vibration and shock absorption. The HPS design with integrated gas–oil chamber is relatively more compact and robust, while mixing gas and oil inside the HPS generates gas–oil emulsion and more nonlinearities. This study formulated a nonlinear analytical model of the compact HPS with gas–oil emulsion, considering the real gas law and pressure-dependent LuGre friction model. The polytropic version of the van der Waals (vdW) method for real gas is applied to represent the thermodynamic behavior of nitrogen. The experimental data were collected at a near temperature of 30°C with three charging pressures under excitations in the frequency range of 0.5–6 Hz, considering two flow connection configurations between chambers as one- and two-bleed orifice. The nonlinear behavior of the gas volume fraction of the emulsion was identified based on peak strut velocity and charge pressure. Discharge coefficients of bleed and check valves were determined as a function of the instantaneous pressure difference between chambers. The parameters of the pressure-dependent LuGre model, such as the stiction force and Coulomb force apart from stiffness and damping coefficient of bristle deflection, were also investigated considering the effect of pressure variation. Compared to the generally used ideal gas and models, the proposed model considerably improved the prediction accuracy of the total force and pressures of HPS, with normalized root-mean-square deviations of about 8%.
Seifi, Abolfazl, Yao, Yumeng, Yin, Yuming, Moore, Masih, Rakheja, Subhash
A Power-Split Hybrid Hydraulic Vehicle Transmission Modeling and Comparative Analysis2010-01-201010/5/2010
Recent innovative drives in hydraulics could introduce very competitive hybrid hydraulic vehicles (HHV). These drives has been considered and analyzed only in the serial HHV architecture. The series-parallel transmission architecture, also called power-split or e-CVT is highlighted as the most popular concept for full (strong) hybrid electric vehicles (HEV). The examples are one-mode power-split in Toyota Prius and two-mode (compound) power-split in GM-Allison EVT. Ambitions to make the hybrid hydraulic power trains better and more efficient would certainly require deeper analysis of more complex power-split (series-parallel) HHV transmission structures and related optimal controls. This paper presents bond graph based mathematical model of kinematics of a one-mode and a two-mode power-split hybrid hydraulic vehicle transmissions which are based on their hybrid electrical counterpart. Such models serve as a basis for the analysis of the steady-state behavior of two representative power-split HHV transmissions. The analysis encloses the power train power flow. Related consideration of limitations and possible energy recuperation is given, too. Obtained kinematics mathematical models provide the basis for their upgrade with dynamics effects using bond-graphs, and the example is given in the paper, as well.
Petric, Josko
Design and Control Considerations for a Series Heavy Duty Hybrid Hydraulic Vehicle2009-01-271711/2/2009
Hybrid hydraulic power trains are a natural fit for heavy duty vehicle applications due to their high power density. This paper describes the analytical formulae available for sizing a series hybrid hydraulic vehicle without changing the engine size. Sizing of pump, accumulator and motor are addressed specifically. A control strategy is also suggested for operating the engine and powertrain pressure close to the best efficiency zones. An example is then given using an FMTV (Family of Medium Tactical Vehicles) platform with a CAT C7 engine. Simulation results are generated using VPSET (Vehicle Propulsion Systems Evaluation Tool), an SwRI-developed vehicle modeling and simulation tool. The hydraulic components are sized according to the recommendations in this paper. The suggested control strategy is implemented in VPSET and performance of the series hydraulic hybrid configuration is compared with that of a conventional powertrain.
Surampudi, Bapi, Nedungadi, Ashok, Ostrowski, Gregory, Montemayor, Alan, Gruenewald, Heather
Validation of a Dynamic Model of a Hybrid Pneumatic Power System2009-01-13044/20/2009
The automotive manufacturing industry has been under tremendous pressure to develop high-efficiency power-train systems because of the considerations of protection of the global environment from vehicle pollution, reduction in fuel consumption, and maintenance of a high level of performance by end-user vehicles. Besides the conventional hybrid electric vehicles, an innovative hybrid pneumatic power system (HPPS) is undergoing research and considered to be a promising technology; it replaces the battery’s electrochemical energy with a high-pressure air storage tank and enables the internal combustion engine (ICE) to function at its sweet spot. The HPPS, which effectively merges both the high-pressure air flow from the storage tank and the recycled exhaust flow from the ICE, thereby increases the thermal efficiency of the ICE and transforms the merged flow energy into mechanical energy using a high efficiency turbine. This paper focuses on the major research process into HPPSs, including overall dynamic simulation and experimental validation. By using the latest simulation tool ITI-Sim, this study demonstrates an experiment which can be operated precisely according to the requirements of various driving conditions under which a car actually runs on the road in accordance with the regulated running vehicle test mode. HPPS is expected to increase the performance of the entire system from 15% to 39%, and is likely to replace the traditional system in the coming years.
Huang, K. David, Nam-Nguyen, Hoai, Quang, Khong Vu
Riveter, Power, Pneumatic-Hydraulic Blind Rivet InstallationAS85188 (Historical)3/29/2002
This specification covers pneumatic-hydraulic tools for use in the installation of type I blind rivets conforming to MIL-R-7885 (see 6.1).
EG-1B Hand Tools Committee
**See J1926/01, /02 & /03***J1926_198808 (Current)8/1/1988
Hydraulic Tube Fittings Committee
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