Maha Fluid Power (Part 1) – Research Overview

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From this post, iHydrostatics will switch the topic to research field of pump & Motor. 3 posts will be issued to introduce Maha Fluid Power Center in Purdue University. During the last decade, Maha research center has achieved fruitful achievements on fluid power transmission and control. Part 1 is to have an overview of Maha research works; Part 2 is to introduce the frontier study of piston micro-surface profile; Part 3 is to have a look at the softwares that Maha has developed for pump&System design and optimization.

1Research ActivitiesFirst of all, iEditor would like to introduce a video in which Professor Monika has presented the main areas her team is working on. Hope you will get a general overview what they are doing and what they have achieved in these areas. Take a look.

Efficient Hydraulic Actuation and Drive Systems1Advanced Energy-Saving Circuits for Hydraulic ActuationThis research area involves the development of novel throttle-less hydraulic actuation architectures together with necessary motion control concepts, to improve system efficiency while maintaining or improving productivity.
In August 2010, a prototype 5-ton DC excavator built at Maha, using pump-controlled actuation (PCA) for all functions showed 40% fuel savings in side-by-side measurements against a standard 5-ton excavator using load-sensing architecture.

2Novel Energy-Saving Electrohydraulic Steer-by-Wire System via Pump Displacement Control ActuationPump displacement control (DC) is an energy-efficient alternative to traditional valve control. A novel steer-by-wire (SBW) technology based on DC actuation is also within the research scope. Hydraulic schematic of this kind of system is shown below. Two main components are together performed in the DC steering system: a dedicated variable displacement pump and a tactile feedback device to control the steering wheel torque level.

Meanwhile, a high-fidelity nonlinear dynamic model is generated for the entire vehicle system, which includes a hydraulics module modeled in MATLAB Simulink and a mechanics model in MSC Adams software as shown below, the two models are coupled at the steering actuator interface.

3Novel Blended Hybrid Architecture“Blended Hydraulic Hybrid” has several advantages over existing hydraulic hybrid transmission configurations. The core of this system combines a hydrostatic transmission with a uniquely connected high pressure accumulator. This partial separation of power transmission from energy storage enables the blended hybrid to maximize efficiency through an optimal combination of system pressure and unit displacements.

Design and Optimization of Piston Pumps and Motors1Multi-Domain ModelingMaha has combined experimental research with advanced multi-domain modeling to discover the secrets of the fluid film lubrication performance between the three primary sliding interfaces of a swash plate type axial piston pump or motor:
Piston/cylinder block bore interface
Cylinder block/valve plate interface
Slipper/swash plate interface

The major breakthrough most recently on the tribological sliding interface in Maha Fluid Power Center was the discovery of the fundamental importance of elasto-hydrodynamic and thermal effects on film generation and film stability.Fluid Film Finite Volume Non-Isothermal Flow Model, Solids Finite Element Heat Transfer Model and Solids Finite Element Elastic Deformation Model are coupled together and communicate with each other during the simulation. In this way, more accurate results can be simulated to predict the behavior and performance of the main tribological interfaces.
Piston/Cylinder BlockFluid-Structure-Thermal Interaction Model

Slipper/Swash PlateFluid-Structure-Thermal Interaction Model

Valve Plate/Cylinder BlockFluid-Structure-Thermal Interaction Model

2TransModelSimulation software TransModel is developed to investigate different factors such as rotating group design and hose dimensions which have an effect on the overall noise of the system, the approach of this simulation model aims to reduce the noise generation at the system level.

2Test RigsMaha center currently has 11 test rigs designed to support various researches. Limited to the content of post, iEditor only share 5 of them. If you are interested in more information, please feel free to contact iHydrostatics.
1EHD Test RigThe EHD test rig is designed to measure the dynamic pressure field in the gap between piston and cylinder and the surface temperature distribution in the cylinder of a swash plate axial piston pump. A special test pump with a single piston cylinder assembly has been designed for this test rig.

2OLEMS Test RigThis rig is designed to investigate the temperature behavior in swash plate axial piston pumps. Sixty thermocouples are mounted around a single cylinder to measure the temperature field during operation of the pump. Telemetry is used for data transfer from the rotating cylinder block to the data acquisition board. The measured results are used for the development of a more precise method to calculate the non-isothermal gap flow between piston and cylinder in swash plate type axial piston machines.

3Tribo Test RigThe heart of the test rig, the Tribo pump (below, left), is designed to measure the dynamic axial and circumferential friction forces between the piston and cylinder. Data is transmitted wirelessly from the rotating kit to a data acquisition via a telemetry system.

4Hardware-in-the-Loop Transmission Test RigThe test rig (left) can be easily switched between a series hybrid and a novel blended hydraulic hybrid transmission. The test rig (right) is designed for the purpose of testing powertrains and powertrain control concepts.

5Slipper Film Thickness Measurement Test RigA swash plate type piston pump was modified to incorporate six high-speed eddy current displacement transducers into the swash plate running face. These sensors directly measure the transient fluid film thickness between the swash plate and slipper during actual machine operation.

3Test Beds
In addition to the stationary test rigs, the Maha Fluid Power Research Center also houses several vehicles that either have been used or are being used currently as platforms for demonstrating and/or investigating new fluid power systems concepts.
In addition to the stationary test rigs, the Maha Fluid Power Research Center also houses several vehicles that either have been used or are being used currently as platforms for demonstrating and/or investigating new fluid power systems concepts.
5-ton wheel loader was overhauled to implement a displacement controlled (DC) steer-by-wire (SbW) system.
Mini-excavator prototype with DC hydraulic hybrid was entirely overhauled to implement the latest advance in DC actuation.
For the purpose of demonstrating active vibration damping through displacement control, a Bobcat skid-steer loader was modified.

4More about Maha
More again. Follow the steps of Professor Monika to have a vivid tour of Maha Fluid Power Research Center. Hope you will enjoy it.

REFERENCES

[1]. Maha Fluid Power Research Center. 2014 Annual Report.
[2]. YouTube video.

STATEMENT

[1]. Copyright of the pictures, videos and paragraphs quoted in this post belong to the original author.
[2]. iHydrostatics is only the platform to share but not create information, iHydrostatics post is NOT intended for academic research.
[3]. This post reprint should be noted with “iHydrostatics Original”.