Abstract

The paper investigates hydraulic wave propagation phenomena through hydraulic circuits of power transmission systems by means of numerical approaches. The actuation circuit of a Dual-Clutch Transmission (DCT) power transmission system supplied by a Gerotor pump is analyzed. A steady state approach is adopted to detect resonance phenomena due to Gerotor design parameters and circuit lengths, while one-dimensional numerical models are implemented to predict the pressure oscillations through the hydraulic ducts for the whole pump operating domain. CFD-1D pipelines are adopted to address the pressure oscillation behavior through the hydraulic pipeline, while spectral maps and order tracking techniques are used to evaluate their fluctuation intensity in function of the pump speed rate. The numerical models are validated with experimental tests performed on an ad hoc test rig for power transmission systems and a good match is found between the numerical and the experimental results. Pump design parameters as well as hydraulic accumulators and resonators are numerically investigated to quantitatively evaluate their improvement on the circuits’ hydro-dynamic behavior. Furthermore, simplified numerical models are implemented to investigate the frequency response behavior of the hydraulic circuits by means of linear analysis. This approach resulted to be particularly effective for the prediction of the resonance frequencies location, and it can be adopted as an optimization tool since significant simulation time can be saved. Finally, the performance of the circuits operating with an eco-friendly fluid is evaluated numerically and the results are compared with the ones obtained with a traditional petroleum-based oil.

Highlights

  • Numerical models are important tools in the design of hydraulic circuits for the prediction of their hydrodynamic behavior to evaluate their performance and detect unexpected anomalies, such as pressure oscillations and resonances that may generate instabilities and undesired noises

  • The hydraulic circuit of the power transmission systems of high-performance cars are generally characterized by strict geometrical constraints, due to the necessity of lightweight and compact systems design, and high speed volumetric pump as supply system, such as Gerotor gear pumps system since they guarantee high performance for the wide operating range of the engine speed

  • The hydraulic circuit of a Dual-Clutch Transmission (DCT) power transmission system adopted in high performance cars is analyzed by means of lumped and distributed parameters models for the investigation of resonance phenomena due to system design

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Summary

Introduction

Numerical models are important tools in the design of hydraulic circuits for the prediction of their hydrodynamic behavior to evaluate their performance and detect unexpected anomalies, such as pressure oscillations and resonances that may generate instabilities and undesired noises. The hydraulic circuit of a Dual-Clutch Transmission (DCT) power transmission system adopted in high performance cars is analyzed by means of lumped and distributed parameters models for the investigation of resonance phenomena due to system design. These circuits are characterized by several components, such as pumps, valves, pistons, and ducts, which could resonate in specific actual operating conditions. The performance of the circuit operating with petroleum-based oil and eco-friendly fluid are compared to evaluate the applicability of biodegradable fluid in the power transmission field to reduce the environmental impact

Materials and Methods
Results
Steady State Model
Base Circuit
Modified Circuits
Full Text
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