| 1. |
- Heeger, Thomas, et al.
(författare)
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A New Degree of Freedom for Variable Axial Piston Pumps with Valve Plate Rotation
- 2021
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Ingår i: Proceedings of the 17:th Scandinavian International Conference on Fluid Power, SICFP’21, June 1-2, 2021, Linköping, Sweden. - Linköping : Linköping University Electronic Press. - 9789179290139 ; , s. 117-133
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Konferensbidrag (refereegranskat)abstract
- Conventionally, variable axial piston machines vary displacement by adjusting the length of the piston stroke, which can be done by adjusting the angle of the swash plate in swash plate machines or the angle of the cylinder block in bent axis machines. Another possibility to achieve variable displacement is to rotate the valve plate and thus adjust the effective use of the piston stroke. An advantage of this method is that it only requires small forces and is easier to control in comparison to conventional displacement adjustment.This idea is not new, and the concept was studied decades ago, but unfortunately, cavitation and high pressure peaks in the bridge between the kidneys hindered a successful implementation of valve plate rotation.Using a double pump with opposing pistons offers the potential to overcome these obstacles, as the displacement can be adjusted by joint rotation of both valve plates, and the effective bridge angles can be adjusted by relative rotation of the valve plates. This paper presents a methodology to optimise valve plate kidney angles for a double pump with rotating valve plates. Optimisation results for exemplary sets of operating points are presented. At high setting ratios, power losses and flow pulsations can be reduced. The risk of cavitation and high pressure peaks can be eliminated, but at the expense of cross-porting and increased losses at low setting ratios and high speeds.
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| 2. |
- Kärnell, Samuel, 1993-, et al.
(författare)
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Pump-Controlled Actuators with Dump Valves
- 2021
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Ingår i: Proceedings of the 17:th Scandinavian International Conference on Fluid Power. - Linköping : Linköping University Electronic Press. - 9789179290139
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Konferensbidrag (refereegranskat)
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| 3. |
- Larsson, L. Viktor, 1990-, et al.
(författare)
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Control Optimisation of a Pump-Controlled Hydraulic System using Digital Displacement Pumps
- 2021
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Ingår i: Proceedings of the 17:th Scandinavian International Conference on Fluid Power, SICFP’21, June 1-2, 2021, Linköping, Sweden. - : Linköping University Electronic Press. - 9789179290139
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Konferensbidrag (refereegranskat)abstract
- When dealing with electrification of working machines, energy-efficient operation is key to maximise the usage of the limited capacity of on-board batteries. Previous research indicate that plenty is gained by reducing component and system losses by means of design. In contrast, this paper focuses on how to maximise energy efficiency by means of control optimisation. Dynamic programming with backward-facing simulationis used to find the optimal electric motor speed trajectory for a scooptram machine equipped with pump control, using digital displacement pumps with dynamic flow sharing as enabling technology. The results show that low shaft speed is preferred to minimise drag losses from parasitic components, partly facilitated by the relatively high and operation point-independent efficiencies of the pumps and electricmotor. The results indicate energy reduction of 5 - 9 %, where higher figures could beexpected for other, more hydraulic-intense applications, such as excavators.
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| 4. |
- Raduenz, Henrique, 1990-, et al.
(författare)
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Improving the efficiency of valve-controlled systems by using multi-chamber actuators
- 2021
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Ingår i: Proceedings of the 17:th Scandinavian International Conference on Fluid Power, SICFP’21, June 1-2, 2021, Linköping, Sweden. - : Linköping University Electronic Press. - 9789179290139 ; , s. 224-236
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Konferensbidrag (refereegranskat)abstract
- This paper outlines how multi-chamber actuatorscan improve the efficiency of valve-controlled systems.Resistive control is a major source of energy losses invalve-controlled systemsthat share the same pumpto drive multiple loads. In the proposed concept, by selectingdifferent chambers,the load on the multi-chamber actuator can be transformed into different pressure and flow rate levels, allowingthe adaptation of its load to the loads on otheractuators. Thiscan lead to a reduction of resistive control energy losses that occur between pump and actuatorswhen driven simultaneously.Suchsystemsareseen as an intermediate solution between resistive conventionalhydraulics and throttle-less digital hydraulics. As a casestudyto highlight the possible efficiency improvement, a concept of a load sensing system with a conventional and a multi-chamber actuatoris analysed. To determine itsefficiency,the equations that describe its static behaviour are presented. Evaluating them for a set ofload forces and speeds demonstrates how the load transformation occursand how it canimprove efficiency.
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| 5. |
- Rankka, Amy, 1991-
(författare)
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Loss Analysis and Concept Comparison for Electrically Driven Hydraulic Loader Crane
- 2021
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Ingår i: Proceedings of the 17:th Scandinavian International Conference on Fluid Power, SICFP’21, June 1-2, 2021, Linköping, Sweden. - Linköping : Linköping University Electronic Press. - 9789179290139 ; , s. 237-251
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Konferensbidrag (refereegranskat)abstract
- The load-sensing system has for a long time been the most energy efficient hydraulic system widely used for mobile machines. When replacing the combustion engine drive with an electric drive with a battery as energy source an incentive for using more energy efficient systems arise. Some promising examples of more energy efficient systems are independent metering systems, pump controlled systems and open flow control systems. Before getting to deeply involved in a specific design, an investigation of the intended application is of importance. The objective of this study is to present a large number of energy efficient designs for the hydraulic system of an electrified loader crane by the means of a loss analysis and a high level concept comparison. To be able to cover a large design space all systems are modeled based on static pressure-flow relations for their components.Based on measurements, the losses from simultaneous operation, backpressure losses and load holding valve losses are found to be the largest loss contributors in the hydraulic system. If an electrical supply system is added to the reference load sensing system, the overall efficiency is found to be 23 %. The hydraulic system it is found to account for 62 % of the losses and the drive system for 38 %.The concept comparison shows that a two or four pump system with recuperation possibilities can decrease the energy consumption of the complete system on the studied working pattern by about 50 %.
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