Spark ignition internal combustion engine efficiency improvement - a variable compression ratio option

Pressure to reduce energy consumption is increasing. The problem of vehicle fuel consumption and emissions is approached by exploring various vehicle propulsion options, assessing their net eff�ectiveness on a energy conversion basis and on a usability (consumer appeal) basis. Life Cycle Assessment (LCA) of various options indicates that internal combustion engine powered vehicles compare favourably because of low production cost in spite of only achieving modest energy conversion efficiency in operation. Spark ignition (SI) homogeneous charge engines have dominated as passenger vehicle power plants, and are likely to maintain their prevalence for passenger vehicle propulsion into the future, but efficiency improvements are required and achievable. Throttling losses are a signifi�cant contributor to reduced efficiency at low load for SI engines which is the load range most employed in standard driving behaviour. An Induction Air Motor (IAM) was conceived, designed, simulated and prototyped to evaluate the potential to recover some of the work the engine does to reduce its intake air pressure for low load operation. The prototyped IAM produced work which potentially could contribute to the engine output while reducing the intake pressure resulting in improved efficiency. However, further eff�ort is required to reduce the friction in the IAM and optimise the work produced by the IAM. An alternative strategy for efficiency improvement involves high Compression Ratio (CR) in conjunction with a reduced compression stroke volume achieved by Late Valve Closing (LVC). Such an arrangement of the Atkinson cycle is shown by simulation to produce improved brake efficiency in SI engines. In this cofin�guration, the maximum power produced by the engine is considerably lower than the maximum power that is achieved by the same displacement for a full compression stroke. To achieve both the improved efficiency at low load using the Atkinson confi�guration and the power achievable from a full induction stroke, the engine requires Variable Compression Ratio (VCR). Assessment of VCR concepts from literature and patents identifi�ed that the complexity of continuously variable compression ratio designs prevented their development to production-ready con�figurations. A simulation of fuel consumption over a standard driving cycle showed that a two-position VCR arrangement produces the same bene�t as a continuously variable CR for physically achievable piston-rod-crank cofin�gurations. Experiments with supporting simulations were performed for a previously patented two-position VCR device, an eccentric link in the big-end of the connecting rod. This work concludes that the eccentric link is not a viable VCR mechanism. An alternative VCR device involving a hydraulic connecting rod was prompted by further experiments and simulations which identifi�ed the behaviour of oil when compressed at high rates in a hydraulic cylinder impacted by a falling mass. The oil impact work suggested that oil chambers of cross-sectional area that could be arranged in a conventional connecting rod could readily support the loads experienced by the rod in a conventionally con�figured engine, so the design and prototyping of a hydraulic connecting rod proceeded. Experiments and simulation confi�rmed that a relatively easily manufactured hydraulic connection rod can be successfully operated in an engine, achieving controllable two-position VCR. Further development of the hydraulic connecting rod control device and improved production techniques are recommended for this new two-position hydraulic VCR device

On-sky single-mode fiber coupling measurements at the Large Binocular Telescope

The demonstration of efficient single-mode fiber (SMF) coupling is a key requirement for the development of a compact, ultra-precise radial velocity (RV) spectrograph. iLocater is a next generation instrument for the Large Binocular Telescope (LBT) that uses adaptive optics (AO) to inject starlight into a SMF. In preparation for commissioning iLocater, a prototype SMF injection system was installed and tested at the LBT in the Y-band (0.970-1.065 $\mu$m). This system was designed to verify the capability of the LBT AO system as well as characterize on-sky SMF coupling efficiencies. SMF coupling was measured on stars with variable airmasses, apparent magnitudes, and seeing conditions for six half-nights using the Large Binocular Telescope Interferometer. We present the overall optical and mechanical performance of the SMF injection system, including details of the installation and alignment procedure. A particular emphasis is placed on analyzing the instrument's performance as a function of telescope elevation to inform the final design of the fiber injection system for iLocater.Comment: 11 pages, 7 figure

Miniaturized modular manipulator design for high precision assembly and manipulation tasks

In this paper, design and control issues for the development of miniaturized manipulators which are aimed to be used in high precision assembly and manipulation tasks are presented. The developed manipulators are size adapted devices, miniaturized versions of conventional robots based on well-known kinematic structures. 3 degrees of freedom (DOF) delta robot and a 2 DOF pantograph mechanism enhanced with a rotational axis at the tip and a Z axis actuating the whole mechanism are given as examples of study. These parallel mechanisms are designed and developed to be used in modular assembly systems for the realization of high precision assembly and manipulation tasks. In that sense, modularity is addressed as an important design consideration. The design procedures are given in details in order to provide solutions for miniaturization and experimental results are given to show the achieved performances

Design and Evaluation of the LOPES Exoskeleton Robot for Interactive Gait Rehabilitation

This paper introduces a newly developed gait rehabilitation device. The device, called LOPES, combines a freely translatable and 2-D-actuated pelvis segment with a leg exoskeleton containing three actuated rotational joints: two at the hip and one at the knee. The joints are impedance controlled to allow bidirectional mechanical interaction between the robot and the training subject. Evaluation measurements show that the device allows both a "pa- tient-in-charge" and "robot-in-charge" mode, in which the robot is controlled either to follow or to guide a patient, respectively. Electromyography (EMG) measurements (one subject) on eight important leg muscles, show that free walking in the device strongly resembles free treadmill walking; an indication that the device can offer task-specific gait training. The possibilities and limitations to using the device as gait measurement tool are also shown at the moment position measurements are not accurate enough for inverse-dynamical gait analysis

N<i>e</i>XOS – the design, development and evaluation of a rehabilitation system for the lower limbs

Recent years have seen the development of a number of automated and semi-automated systems to support for physiotherapy and rehabilitation. These deploy a range of technologies from highly complex purpose built systems to approaches based around the use of industrial robots operating either individually or in combination for applications ranging from stroke to mobility enhancement. The NeXOS project set out to investigate an approach to the rehabilitation of the lower limbs in a way which brought together expertise in engineering design and mechatronics with specilists in rehabilitation and physiotherapy. The resulting system has resulted in a prototype of a system which is capable in operating in a number of modes from fully independent to providing direct support to a physiotherapist during manipulation of the limb. Designed around a low cost approach for an implementation ultimately capable of use in a patients home using web-baased strategies for communication with their support team, the prototype NeXOS system has validated the adoption of an integrated approach to its development. The paper considers this design and development process and provides the results from the initial tests with physiotherapists to establish the operational basis for clinical implementation

A multisensing setup for the intelligent tire monitoring

The present paper offers the chance to experimentally measure, for the first time, the internal tire strain by optical fiber sensors during the tire rolling in real operating conditions. The phenomena that take place during the tire rolling are in fact far from being completely understood. Despite several models available in the technical literature, there is not a correspondently large set of experimental observations. The paper includes the detailed description of the new multi-sensing technology for an ongoing vehicle measurement, which the research group has developed in the context of the project OPTYRE. The experimental apparatus is mainly based on the use of optical fibers with embedded Fiber Bragg Gratings sensors for the acquisition of the circumferential tire strain. Other sensors are also installed on the tire, such as a phonic wheel, a uniaxial accelerometer, and a dynamic temperature sensor. The acquired information is used as input variables in dedicated algorithms that allow the identification of key parameters, such as the dynamic contact patch, instantaneous dissipation and instantaneous grip. The OPTYRE project brings a contribution into the field of experimental grip monitoring of wheeled vehicles, with implications both on passive and active safety characteristics of cars and motorbikes