Volume 1 – Symposium: Tuesday, March 8

Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Components:Group A: Digital Hydraulics Group B: Intelligent Control Group C: Valves Group D | G | K: Fundamentals Group E | H | L: Mobile Hydraulics Group F | I: Pumps Group M: Hydraulic Component

Energy analysis of a hybrid electro-hydraulic system for efficient mobile hydraulics

Energy efficiency plays a significant role in mobile hydraulics due to the high amount of carbon dioxide and pollutants being released into the atmosphere. Efficiency improvements are urgently needed, so the electrification of mobile hydraulics represents a fantastic opportunity in this regard. This approach leads to electro-hydraulic systems that remove functional flow throttling in control valves and enable energy recovery. Fuels savings were already demonstrated in simulation, but the literature does not offer entire energy analyses of these electro-hydraulic solutions. This limitation prevents complete system-level comprehension and does not give enough insight to pinpoint areas for further efficiency improvements. Thus, this paper focuses on a hybrid system for excavators based on electro-hydraulic drives that is compared against the original valve-controlled layout. The objective is to quantify the energy flows insight the excavator during relevant operations and highlight the resulting energy losses. The outcomes confirm that electro-hydraulic solutions are suitable for a low-carbon economy. They indicate hydraulic actuators, speed-controlled pumps, and electric motors as the critical components for further energy efficiency enhancement excluding the combustion engine

Pressure compensator control – a novel independent metering architecture

This contribution presents an operating strategy for a novel valve structure for mobile machines’ working hydraulics which combines the flexibility and energetic benefits of individual metering with the functionality of common primary pressure compensation (IPC). The aim is to set up a system that uses a minimal amount of sensors and simple control algorithms. A control strategy theoretically described in /1/ is modified to facilitate the practical implementation on a mini excavator implement as a test rig. This test rig consists only of components that are currently available off-the-shelf to show that it is possible to develop an individual metering system under these economic restrictions. The novel is more energy efficient than common flow sharing systems but provides the same functionality. The control algorithm is experimentally evaluated in terms of functionality and energy consumption. Simulations show potential for further improvements

Hydraulic Hybrid Excavator: Layout Definition, Experimental Activity, Mathematical Model Validation and Fuel Consumption Evaluation

Energy saving and fuel consumption reduction techniques are among the principal interests for both academic institutions and industries, in particular, system optimization and hybridization. This paper presents a new hydraulic hybrid system layout for mobile machinery implemented on a middle size excavator. The hybridization procedure took advantage of a dynamic programming (DP) algorithm, which was also utilized for the hybrid components dimensioning and control strategy definition. A dedicated experimental activity on test bench was performed on the main components of the energy recovery system (ERS). The JCMAS working cycle was considered as the reference test for a fuel consumption comparison between the standard and the hybrid excavator. A fuel saving up to 8% on the JCMAS cycle, and up to 11% during the digging cycle, has been allowed by the proposed hybrid system

A hydraulic test stand for demonstrating the operation of Eaton’s energy recovery system (ERS)

Fuel cost represents a significant operating expense for owners and fleet managers of hydraulic off-highway vehicles. Further, the upcoming Tier IV compliance for off-highway applications will create further expense for after-treatment and cooling. Solutions that help address these factors motivate fleet operators to consider and pursue more fuelefficient hydraulic energy recovery systems. Electrical hybridization schemes are typically complex, expensive, and often do not satisfy customer payback expectations. This paper presents a hydraulic energy recovery architecture to realize energy recovery and utilization through a hydraulic hydro-mechanical transformer. The proposed system can significantly reduce hydraulic metering losses and recover energy from multiple services. The transformer enables recovered energy to be stored in a high-pressure accumulator, maximizing energy density. It can also provide system power management, potentially allowing for engine downsizing. A hydraulic test stand is used in the development of the transformer system. The test stand is easily adaptable to simulate transformer operations on an excavator by enabling selected mode valves. The transformer’s basic operations include shaft speed control, pressure transformation control, and output flow control. This paper presents the test results of the transformer’s basic operations on the test stand, which will enable a transformer’s full function on an excavator

Downsizing the electric machines of energy-efficient electro-hydraulic drives for mobile hydraulics

The poor energy efficiency of state-of-the-art mobile hydraulics affects the carbon dioxide released into the atmosphere and the operating costs. These crucial factors require urgent improvements that can be addressed by the electrification of fluid power. This approach has already generated electro-hydraulic drives that remove flow throttling and enable energy recovery. However, the entire power managed by the actuators of conventional systems must pass through the electric machines. This characteristic is unfeasible for medium-to-high power applications since they need electric motors and electronics with high power ratings and large onboard generation of electricity. Thus, this paper applies to a hydraulic excavator’s boom the idea of splitting the power being transferred to/from the actuator between the hydraulic and electric domains (i.e., a centralized hydraulic power supply is involved). The objective is downsizing the power rating of the boom’s electric components while maintaining the highpower output of the hydraulic actuator. The results show the expected behavior of the hybrid excavator in terms of motion control, but only 57% of the boom’s peak power is now exchanged electrically. The resulting electric machine with 61% downsizing favors the system’s cost and compactness supporting the electrification process that is aligned with the low-carbon economy

Toward Supervisory-Level Control for the Energy Consumption and Performance Optimization of Displacement-Controlled Hydraulic Hybrid Machines

Environmental awareness, production costs and operating expenses have provided a large incentive for the investigation of novel and more efficient fluid power technologies for decades. In the earth-moving sector, hydraulic hybrids have emerged as a highly efficient and affordable choice for the next generation hydraulic systems. Displacementcontrolled (DC) actuation has demonstrated that, when coupled with hydraulic hybrids, the engine power can be downsized by up to 50% leading to substantial savings. This concept has been realized by the authors‘ group on an excavator prototype where a secondary-controlled hydraulic hybrid drive was implemented on the swing. Actuatorlevel controls have been formulated by the authors‘ group but the challenge remains to effectively manage the system on the supervisory-level. In this paper, a power management controller is proposed to minimize fuel consumption while taking into account performance. The algorithm, a feedforward and cost-function combination considers operator commands, the DC actuators‘ power consumption and the power available from the engine and hydraulic hybrid as metrics. The developed strategy brings the technology closer to the predicted savings while achieving superior operability

An idea of the electronic control system for the multifunctional hydraulic machine

The paper presents an electronic control system for application in mobile hydraulic systems. Key components of the system and its advantages have been discussed. A multifunctional hydraulic machine, its design and operation principle have been presented. The concept of control work machine with the electronic control system has been developed. The benefits of integration of these systems have been highlighte

The Working Hydraulics of Valve-Controlled Mobile Machines: Classification and Review

Productivity, reliability, controllability, flexibility and affordable costs represent key aspects in mobile machines. Additionally, due to the high fuel price and to the introduction of stringent emission regulations for diesel engines, the reduction of fuel consumption while persevering the existing performance is the current demand. In order to satisfy and maximize the above requirements, different hydraulic system architectures have been developed during the last decades. Both academia and industry have been investing considerable resources delivering numerous outcomes that require a classification. This review paper closes this gap by analyzing and classifying the working hydraulics of non-hybrid, valve-controlled mobile machines starting from the 1980s to the state-of-the-art. Hydraulic layouts are addressed and categorized by both discussing their fundamentals and evolutions, and by pointing out their pros and cons in a way to provide the readers with a comprehensive overview of the systems currently available on the market and at the research stage

Factors affecting the development of collaborative improvement with strategic suppliers

The research presented in this paper was aimed at increasing the current understanding of the process of developing collaborative improvement in Extended Manufacturing Enterprises (EME). Theory suggests a number of factors to affect that process, including shared sense of direction (i.e. vision), trust, power, and commitment. Based on action research of three EMEs involving a total of thirteen companies from five European countries, the present study identifies a number of additional factors. Factors exogenous to, but impacting, the collaboration are joint history and culture. Endogenous factors are approach to establishing the collaboration, project organisation, change and improvement competence, ways and modes of communicating, and political behaviour. Not only do these factors influence each other, they also strongly affect the development of collaborative improvement