Crank Rotation Research Articles

A computational fluid dynamics model to evaluate the inlet stroke performance of a positive displacement reciprocating plunger pump

A computational fluid dynamics model of the middle chamber of a triplex positive displacement reciprocating pump is presented to assess the feasibility of a transient numerical method to investigate the performance of the pump throughout the 180° of crank rotation of the inlet stroke. The paper also investigates, by means of computational fluid dynamics, the pressure drop occurring in the pump chamber during the first part of the inlet stroke in order to gain a better understanding of the mechanisms leading to cavitation. The model includes the compressibility of the working fluid and the lift of the inlet valve as a function of the pressure field on the inlet valve surfaces. It also takes into account the valve spring preload in the overall balance of forces moving the valve. Simulation of the valve motion was achieved by providing the solver with two user-defined functions. The plunger lift–time history was defined by the crank diameter and connecting rod length. This paper will demonstrate the feasibility and reasonable accuracy of the method adopted by comparison with experimental data.

2A1-U01 脳波を用いた人とロボットの協調に向けた基礎的検討 : 作業中の負荷変化時の脳波解析(人間機械協調)

In this paper, aiming at human-robot cooperation using electroencephalogram (EEG), we studied on EEG when the load changed during a task. EEG and electromyogram (EMG) signals were recorded during a crank rotation task, where the load of the task was changed at random timing. Frequency spectra of the recorded EEG signals were analyzed, and difference between ON and OFF of the load was observed.

A New Postural Force Production Index to Assess Propulsion Effectiveness During Handcycling

The aim of this study was to propose a new index called Postural Force Production Index (PFPI) for evaluating the force production during handcycling. For a given posture, it assesses the force generation capacity in all Cartesian directions by linking the joint configuration to the effective force applied on the handgrips. Its purpose is to give insight into the force pattern of handcycling users, and could be used as ergonomic index. The PFPI is based on the force ellipsoid, which belongs to the class of manipulability indices and represents the overall force production capabilities at the hand in all Cartesian directions from unit joint torques. The kinematics and kinetics of the arm were recorded during a 1-min exercise test on a handcycle at 70 revolutions per minute performed by one paraplegic expert in handcycling. The PFPI values were compared with the Fraction Effective Force (FEF), which is classically associated with the effectiveness of force application. The results showed a correspondence in the propulsion cycle between FEF peaks and the most favorable postures to produce a force tangential to the crank rotation (PFPI). This preliminary study opens a promising way to study patterns of force production in the framework of handcycling movement analysis.

The Methods to Study the Influence of the Clearance in the Case of Great Speeds and Small Speeds

In kinematic couplings, clearances are inevitable for their operation. The size of these clearances but as a consequence of use, causes a malfunction of the mechanism to which it belongs. The law of motion of driveline changes, big clearances, non-technological system causes vibration, leading to discomfort, uncertainty, and thus reach its degradation. In the paper we shall make a few of geometric and mechanical type considerations about the clearances in the linkages, linkages planes with joint rotation links. Based on mathematical algorithm developed and applied crank mechanism, the model presented in [1], this paper scientifically developed mathematical model, proposing mathematical models to study the influence of the size of the clearance in general dynamic calculation mechanisms. Mechanism considered is crank connecting rod mechanism with clearance cinematic coupling between rod and crank rotation. The paper makes a study of the influence on the dynamic behavior of the crank rod mechanism at high speeds, but also general method algorithm is developed and accurate method to assess the dynamic behavior of multi-body mechanism. The first case is considered a constant angular speed motor and thus determine the elemental expressions that establish the mechanism position, velocity and acceleration expressions in the two directions heads elements. Finally we obtain the expression of the normal reaction force, as well as position expression that defines its angle. With reaction force can specify phase (contact, flight, impact) [1], the behavior of the journal. For the case of general method - the method multi-body - the exact method are established liaison relationships between the parameters , write matrices , inertia matrix. Use Lagrange equations, if non-holonomic constraints. Matrix differential equation of motion is written and it can be solved numerically using Runge-Kutta method of order four. Of the iterative method, we obtain the parameters used in calculating the reaction force expression that can be evaluated accurately in journal bearings behaviour. Any would be their source of appearance, they usually produce unwished effects during the mechanisms functioning.

Optimal Design of Compensatory Cam for Precision Corn Planting Device of Furrow Seeder with Vertical Dropping with Whole Plastic-Film Mulching on Double Ridges

The design focus of precision corn planting device of furrow seeder with vertical dropping with whole plastic-film mulching on double ridges is to optimize its compensatory cam, and it aims to make compensation for the horizontal velocity of soil opener when the whole machine is moving forward. Under the precondition of ensuring sowing with vertical dropping by soil opener, the structure of compensatory cam shall also meet the requirements of smooth transition, space and cost saving. In order to achieve the above-mentioned design goals, the forward speed of machines and tools, the horizontal distance between the supporting point of amplification mechanism and the centering point of crank rotation, and the horizontal distance between cam and the centering point of crank rotation are taken as the experimental factors, offset circle radius, small-curvature radius and mass are regarded as the experimental indicators, therefore three factors and three levels orthogonal experiment is carried out, it is obtained that the optimal combination is A1B2C1 by analyzing the results of experiment.

Dynamic characteristics of suction valves for reciprocating compressor with stepless capacity control system

The dynamic characteristics of suction valves for reciprocating compressor with a stepless capacity control system are studied in this article. The self-acting valve model that is applicable for stepless capacity control condition is derived. For the suction valve movement controlled by actuator, a simulation of the hydraulic and mechanical system is conducted. An experimental platform is setup, which is used to test the valve dynamic when it is controlled by actuator. The results from the mathematical model show that the valve impact speeds are influenced by the valve lift, Mach number of the flow in the valve clearance and the initial crank rotation angle of the valve closing process. The simulation results agree well with experimental results. The simulated maximum speed is about 0.53 m/s, and the maximum speed tested by experiment is about 0.58 m/s, both of which are much lower than the speed of the automatic valve (3 m/s). In addition, simulation results show that the maximum speed is at constant when the hydraulic piston stroke increases, which is much different from the automatic valve. It becomes apparent from the aforementioned results that with stepless capacity control system the dynamic characteristics of the suction valve are changed. The valve can be limited at a low speed, and the valve impact speeds to seat and stopper decrease significantly, which would be helpful for extending the life of the valve plate.

Upgrading of associated petroleum gas into methane-rich gas for power plant feeding applications. Technological and economic benefits

Laboratory studies of the reaction of steam reforming of light hydrocarbons into methane–hydrogen mixture were performed. Ni- and Ru-containing systems were studied as the catalysts. The design, scale-out, and operation of an APG catalytic reformer integrated with evaporator-heat-exchanger, water condenser and flame burner were reported. Conversion of heavier hydrocarbon components into methane–hydrogen gas mixture exceeded 95–99% during testing the catalytic reformer at 270–360°C. Increasing reaction temperature led to increasing H2 and CO contents in the reaction mixture and complete conversion of LPG and ethane fractions. Both initial and reformed APG were used for fueling a power generation unit on the base of gas internal combustion engine MTES-30. In case of initial APG fueling, the power derating was 22%, exhaust gas contained black smoke. When the power generation unit was fueled by methane–hydrogen mixture produced by APG catalytic reforming, the engine power attained the nominal value; the engine showed excellent dynamic and temperature characteristics, stably supported crank rotation frequency.According to economic analysis concerning different types of power plants with electric power of ∼1000kW, the plants equipped with a catalytic reformer of APG into methane–hydrogen mixture show faster payback of capital investments, as compared to the plants fed by APG directly, due to longer service life, longer overhaul intervals, and low rated power losses. Сatalytic reforming of APG into methane–hydrogen mixture is a promising approach for solving APG utilization problem.

Design and testing of an MRI-compatible cycle ergometer for non-invasive cardiac assessments during exercise

BackgroundMagnetic resonance imaging (MRI) is an important tool for cardiac research, and it is frequently used for resting cardiac assessments. However, research into non-pharmacological stress cardiac evaluation is limited.MethodsWe aimed to design a portable and relatively inexpensive MRI cycle ergometer capable of continuously measuring pedalling workload while patients exercise to maintain target heart rates.ResultsWe constructed and tested an MRI-compatible cycle ergometer for a 1.5 T MRI scanner. Resting and sub-maximal exercise images (at 110 beats per minute) were successfully obtained in 8 healthy adults.ConclusionsThe MRI-compatible cycle ergometer constructed by our research group enabled cardiac assessments at fixed heart rates, while continuously recording power output by directly measuring pedal force and crank rotation.

Dynamic Behaviour of a Novel Compliant MEMS Force Amplifier by MATLAB/SIMULINK

High force amplification in micro-scale can be achieved by MEMS compliant systems and such systems have been recently preferred to obtain high output forces in micro actuators due to its monolithic structure and ease of fabrication. We studied the mechanism of novel MEMS force amplifier in dynamic mode by modeling its rigid body mechanism with Matlab/Simulink programming. Kinematic analysis and dynamic response of the MEMS compliant system was obtained by modeling of velocity and acceleration parameters, and ramp input function, respectively. We found that the output force goes to infinity at zero-crank angle and there is 2650 times force amplification by a given very small crank rotation about 2.30.

Modelling and analysis of an ionic polymer-metal composite (IPMC)-rocker-based four-bar for variable path generation using the Euler—Bernoulli approach

This article evaluates the dynamic performance of a partially compliant four-bar mechanism having an ionic polymer-metal composite (IPMC)-based rocker. The rigid link rocker is replaced with an IPMC actuator for variable path generation. The study aims to address the size limitations of a traditional variable length rigid link rocker, which is actuated by an electric motor for miniature micro-scale applications. Dynamic modelling is carried out taking into account the bending property of the IPMC and Grashof criterion. Simulations are also performed based on the effective length of IPMC following the Euler—Bernoulli approach with input voltage. The investigation demonstrates that by controlling the bending of IPMC along with the rotation of crank, a definite work volume can be generated at the rocker tip.

1A1-L13 粘弾性特性を考慮したクランクタスクの動作分析

It is important to clarify how the stiffness and the torque of human arm are controlled in the interaction with the environment. So far, the stiffness of human arm has been measured by adding perturbation. But, it is difficult to measure the stiffness in isotonic movements with various loads, because the perturbation provides the unexpected stiffness increase by antagonistic muscles. In this paper, the musculoskeletal model with six muscles is used to estimate the joint torque in crank rotation tasks. The muscular excitation for random disturbance is evaluated.

Kinematic analysis and synthesis of an adjustable six-bar linkage

This paper investigates the kinematics of an adjustable six-bar linkage where the rotation of the input crank is converted into the oscillation of the output link. This single-degree-of freedom planar linkage will be used as a variable-speed transmission mechanism where the input crank rotates at a constant speed and the output link consists of an overrunning clutch mounted on the output shaft. The analysis uses a novel technique in which kinematic coefficients are obtained with respect to an independent variable. Then kinematic inversion is used to express the kinematic coefficients with respect to the input variable of the linkage. This technique decouples the position equations and provides additional insight into the geometry of the adjustable linkage. The angle through which the output link oscillates, for each revolution of the input crank, can be adjusted by a control arm. This arm allows a fixed pivot to be temporarily released and moved along a circular arc about a permanent ground pivot. The paper shows how to determine the angle of oscillation of the output link for a specified position of the fixed pivot and investigates the extreme positions of the output link corresponding to the extreme positions of a point on the coupler link. For this reason, the paper includes a study of the geometry of the path traced by a coupler point and determines the location of the ground pivot of the control arm which will cause the output link to remain stationary during a complete rotation of the input crank. Finally, the paper shows how the kinematic analysis results can be used, in a straightforward manner, to redesign the control arm.

Design of reconfigurable coupled-serial-chain-based manipulation assistive aids

Our goal is to design a reconfigurable single degree-of-freedom (dof) articulated manipulation assistive aid, whose end-effector is required to closely approximate a series of constrained planar paths. To this end, we investigate the viability of the coupled-serial-chain configuration manipulator design created by constraining the relative rotations of a revolute-jointed serial-chain manipulator with linear cable–pulley couplings. The forward kinematics equations take the form of a finite trigonometric series in terms of the input crank rotations. Our proposed Fourier-based synthesis method exploits this special structure to facilitate the design synthesis of such manipulators. We then examine design enhancements, to permit this manipulator to be reconfigured for multiple sets of constrained end-effector tasks, by controlled variation of the principal structural parameters. Particular attention is paid to the creation of a physical prototype, which facilitates such reconfiguration.

The effect of piston friction on the torsional natural frequency of a reciprocating engine

The torsional vibration of systems involving engines exhibits some phenomena not typical of vibration in general. These effects result from the geometry of the reciprocating mechanism and are revealed by detailed kinematic and dynamic analyses. Apart from the system's inertia varying with crank rotation, recent work by the authors has shown that it is also affected by piston-to-cylinder friction. In previous published work, that omitted friction, differences were observed between the measured and the predicted natural frequency function. This short paper revisits those differences and includes friction effects.

Kinematic and Static Analyses of the Pedaling by Means of New Slider-Crank Mechanism

A slider-crank mechanism whose coupler curve is the approximate ellipse is designed so that a man may perform the pedaling of the elliptical motion of the foot. Because the thigh, the shank and the foot constitute the three-link chain, the system of a man and the bicycle with the slider-crank pedal mechanism is the planar seven-link mechanism with two degree freedom. The system of a man and the ordinary bicycle is the planar five-link mechanism with two degree freedom. Kinematic characteristics of these systems are analyzed with the given pattern of the pedal angle curve during a crank rotation. Then, the crank moment and the pin joint forces of these systems are calculated for given patterns of the hip moment and the knee moment during a crank rotation and the average crank moment are estimated. It makes comparative study of calculated and experiment results of the pedal force, the crank moment and physiological results of oxygen uptake and carbon dioxide output in usual crank pedaling and in slider crank pedaling.

1A1-A05 筋骨格ヒューマノイド小太郎の脊椎を利用した視覚に基づくクランク回し行動の獲得(ヒューマノイド)

Musculo-skeletal humanoid has many DOFs and flexible structure, so it can adapt to environment using hardware. To realize adaptation to environment, it is important for musculo-skeletal humanoid to modify its actions by using its own sensors because it is difficult to model for its complex structure. In this paper, by vision-based reinforcement learning, musculo-skeletal humanoid Kotaro aquires crank rotation behavior with flexible spine.

Valve timing and valve lift control mechanism for engines

A new type engine valve control system has been presented, in which both the valve lift and valve timing are controlled directly by electric motors. A mechanism of the valve timing control system is made of planetary gears. The outer gear is the timing pulley which has a timing belt driven by the crankshaft of an engine. Two planetary gears are inside of the pulley. The gears engage with the inner gear of the pulley. The center of the disc, which has centers of the planetary gear, is connected to the camshaft. Then, the crank rotation is transmitted to the camshaft, and rotations of sun gear are added to the rotations of camshaft. This means that when rotation angle of the sun gear is controlled, the phase between the inlet valve and the exhaust valve can be controlled. The lift control system is made of linear slider and ball screw. The cam shape of this system is three-dimensional. The height of the cam varies along the axis of the shaft. When the ball screw rotates, the camshaft slides in the axial direction, so that the lift of the cam varies. The control method is presented for the mechanism, in which valve phase and the lift are controlled continuously. Experimental tests have been carried out for the system.

Fourier Methods for Kinematic Synthesis of Coupled Serial Chain Mechanisms

Single degree-of-freedom coupled serial chain (SDCSC) mechanisms are a class of mechanisms that can be realized by coupling successive joint rotations of a serial chain linkage, by way of gears or cable-pulley drives. Such mechanisms combine the benefits of single degree-of-freedom design and control with the anthropomorphic workspace of serial chains. Our interest is in creating articulated manipulation-assistive aids based on the SDCSC configuration to work passively in cooperation with the human operator or to serve as a low-cost automation solution. However, as single-degree-of-freedom systems, such SDCSC-configuration manipulators need to be designed specific to a given task. In this paper, we investigate the development of a synthesis scheme, leveraging tools from Fourier analysis and optimization, to permit the end-effectors of such manipulators to closely approximate desired closed planar paths. In particular, we note that the forward kinematics equations take the form of a finite trigonometric series in terms of the input crank rotations. The proposed Fourier-based synthesis method exploits this special structure to achieve the combined number and dimensional synthesis of SDCSC-configuration manipulators for closed-loop planar path-following tasks. Representative examples illustrate the application of this method for tracing candidate square and rectangular paths. Emphasis is also placed on conversion of computational results into physically realizable mechanism designs.

Dynamics of Slider-Crank Mechanisms with Flexible Supports and Non-Ideal Forcing

Transient and steady state dynamic response of a class of slider-crank mechanisms is investigated. Specifically, the class of mechanisms examined involves rigid members but compliant supporting bearings. Moreover, the mechanisms are subjected to non-ideal forcing. Namely, both the driving and the resisting loads are expressed as a function of the angular coordinate describing the crank rotation. First, an appropriate set of equations of motion is derived by applying Lagrange's equations. These equations are strongly nonlinear due to the large rigid body rotation of the crank and the connecting rod, as well as due to the nonlinearities associated with the bearing action and the form of the driving and the resisting loads. Consequently, the dynamics of the resulting dynamical system is examined by solving the equations of motion numerically. More specifically, transient response is captured by direct integration, while determination of complete branches of steady state response is achieved by applying appropriate numerical methodologies. Initially, mechanisms whose crankshaft is supported by bearings with rolling elements and linear stiffness characteristics are examined. Then, numerical results are presented for rolling element bearings with nonlinear stiffness characteristics. Finally, the study is focused on mechanisms supported by hydrodynamic bearings. In all cases, the attention is focused on investigating the influence of the system parameters on its dynamics. Moreover, models with constant crank angular velocity are first analysed, since they provide valuable insight into some aspects of the system dynamics. Eventually, the emphasis is shifted to the general case of non-ideal forcing, originating from the dependence of the driving and the resisting moments on the crankshaft motion.

Engine Valve Lift and Phase Control System

A new type engine valve control system has been presented, in which both valve lift and phase are controlled directly by electric motors. A mechanism of the phase control system is made of planetary gears. The outer gear is the timing pulley which has timing belt driven by the crank of an engine. Two planetary gears are inside of the pulley. The gears engage in inner gear of the pulley. The center of the disc which has centers of the planetary gear is connected to the camshaft. Then, the crank rotation is transmitted to the cam shaft, and rotation of sun gear is added to the rotation of cam shaft. This means that when rotation angle of the sun gear is controlled, phase of the cam can be controlled. The lift control system is made of linear slider and ball screw. The cam shape of this system is three-dimensional. The height of the cam varies along the axis of the shaft. Hence, when the ball screw rotates, the cam shaft slides in the axial direction, so that the lift of the cam varies. Experimental tests have been carried out for the system. lt is ascertained that both cam lift and phase can be controlled continuously.