Scotch Yoke Research Articles

Scotch-Yoke mechanism for a syringe pump - A case study

Syringe Pump is mainly used in microfluidics, where precise flow rate is required. Precise flow rate is achieved by using minimum torque and at low speed, for such requirements a mechanism has to be constructed. The input is from a stepper motor, so a rotary to linear motion converting mechanism is required, which will work efficiently on such low torque applications. This work mainly looks into feasibility of scotch yoke rather than conventionally used crank and slider mechanism. Scotch yoke is a rotary to linear conversion mechanism. It contains mainly two parts i) a rolling scotch and ii) a sliding yoke. The yoke is driven by a pin eccentrically placed on the scotch. Since proximity of the mechanism is nearer to the source, the loss accounted is less in the case of scotch yoke. In this work both crank-slider and scotch-yoke are examined through simulation using MSC ADAMS software and the maximum velocity of that can be achieved is obtained analytically through Kinematic analysis of scotch-yoke mechanism.

Energy behavior of an electromechanical system with internal impacts and uncertainties

This paper analyzes the maximal energy stored in an elastic barrier due to the impacts of a pendulum fitted within a vibro-impact electromechanical system considering the existence of epistemic uncertainties in the system parameters. The vibro-impact electromechanical system is composed of two subsystems. The first subsystem is the electromechanical system composed by a motor, cart and pendulum, and the second is an elastic barrier. The first will be called striker system. The pendulum is fitted within the cart. Its suspension point is fixed in the cart, so that it may exist a relative motion between cart and pendulum. The influence of the DC motor in the dynamic behavior of the pendulum is considered. The coupling between the motor and the cart is made by a scotch yoke mechanism, so that the motor rotational motion is transformed in horizontal cart motion over a rail. The pendulum is modeled as a mathematical pendulum (bar without mass and particle of mass mp at the end). A flexible barrier, placed inside the cart, constrains the pendulum motion. Due to the relative motion between the cart and the pendulum, impacts may occur between these two elements. The objective of the paper is to analyze the energy stored in the barrier due to impacts as a function of some parameters of the electromechanical system from a deterministic and from a stochastic viewpoint. The system is designed as an aid in drilling. The impacts damage or fracture the rock and facilitate the conventional drilling.

Design and Testing of an Innovative Wire Transmission for a Quarter-Turn Actuator

The object of this work is the development of an innovative wire actuator in collaboration with Velan ABV S.p.A., which will be mainly used in applications in which high efficiency and linear behavior are desirable specifications. In this work, the main features of the proposed actuator, which is protected by a patent, are evaluated and compared with respect to a conventional solution consisting of a scotch yoke (SY) transmission system. The comparison is performed using both the simulation results and the experimental data. In order to identify the efficiency and the dynamical response of the innovative actuator, the authors have designed a hydraulic test rig, which can be configured to perform different testing procedures. In this way, it is possible to perform both static tests to identify actuator efficiency, and dynamic ones, in which an assigned load or a valve impedance function is simulated to verify the response of the tested actuator in realistic conditions. Finally, the proposed test rig has been successfully employed to perform both reliability and fatigue tests in which the actuator is subjected to realistic and repetitive loads.

Dual Side Water Pumping System using Scotch Yoke Mechanism

The aim of the paper is to design and develop a dual side water pumping system using scotch yoke mechanism. The reciprocating motion of the plunger is utilized for the pumping action. The plunger is reciprocated with the help of a cam plate. By this action the water is pumped with very high pressure and to various heads. This can be utilized for various applications like lubrication in machines and water pumping in agriculture field. The cam plate gets the drive from the motor for its rotation and converts that rotary motion to useful dual side reciprocating motion. The motor is powered with the aid of electric power. Thus the water is pumped from source to various heads.

Design, Modeling, and Experimental Validation of a Novel Infinitely Variable Transmission Based on Scotch Yoke Systems

A novel infinitely variable transmission (IVT) based on scotch yoke systems is designed to provide a continuously varied output-to-input speed ratio from zero to a specified value. By changing the crank length of scotch yoke systems, the speed ratio of the IVT can be continuously adjusted. The IVT consists of a pair of noncircular gears and two modules: an input-control module and a motion conversion module. The input-control module employs two planetary gear sets to combine the input speed of the IVT with the control speed from the stepper motor that changes the crank length of scotch yoke systems. The motion conversion module employs two scotch yoke systems to convert the combined speeds from the input-control module to translational speeds of yokes, and the translational speeds are converted to output speeds through rack–pinions. The speed ratio between the output of the motion conversion module and the input of the input-control module has a shape of a sinusoidal-like wave, which generates instantaneous variations. Use of scotch yoke systems provides a benefit to isolate the interaction between the crank length and the shape of the speed ratio, and a pair of noncircular gears can be used to eliminate the instantaneous variations of the speed ratio for all crank lengths. A prototype of the IVT was built and instrumented, and its kinematic behavior was experimentally validated. A driving test was conducted to examine the performance of the IVT.

Numerical simulation and experimental investigation of a novel Scotch yoke for a Gifford-McMahon cryocooler

A novel Gifford-McMahon (GM) cycle, called an asymmetric GM cycle, is proposed. In an asymmetric GM cycle, the displacer moves slowly when it is adjacent to the upper dead point but moves rapidly when it is adjacent to the lower dead point. Therefore, the expansion process is longer, while the discharging process is shorter than in a conventional GM cycle. Meanwhile, the duration of the charging process can be kept the same as that in a conventional GM cycle. Accordingly, the phase shift between the pressure and the displacement can be improved, and the mass flow rate into the expansion space can also be increased. Therefore, the P-V work and the cooling capacity can be increased. To implement the GM cycle, a novel Scotch yoke was invented. In the Scotch yoke, there is a concave part at the upper center of the slide groove and a convex part at the lower center of the slide groove. The effect of the Scotch yoke has been confirmed by numerical simulation and experimental investigation. With a conventional Scotch yoke, the cooling capacity was 44 W at 37.4 K at the first stage and 1.0 W at 3.94 K at the second stage. With a novel Scotch yoke, the cooling capacity was 44 W at 35.9 K at the first stage and 1.0 W at 3.96 K at the second stage. The cooling capacity at the first stage at 40 K was improved by about 10%, from 51.5 W to 57.3 W.

Two parametric excited nonlinear systems due to electromechanical coupling

This paper analyzes the behavior of two electromechanical systems. In the first part of the work, a simple system is analyzed. It is composed of a cart, whose motion is excited by a DC motor (motor with continuous current). The coupling between the motor and the cart is made by a mechanism called scotch yoke, so that the motor rotational motion is transformed in horizontal cart motion over a rail. The developed model of the system takes into account the influence of the DC motor in the dynamic behavior of the system. It is formulated as an initial value problem, in which the coupling torque between the mechanical and electric systems appears as a parametric excitation. By simulations, it is verified that the system has a periodic solution with a relation 2:1 between the period of rotation of the disk (part of the electromechanical system) and the period of the current in the DC motor. In the second part of the work, a pendulum is embarked into the cart. Its suspension point is fixed in cart, so that there exists a relative motion between the cart and the pendulum. The excitation of the pendulum comes from the motion of the cart, so it is not controlled and can vary widely because the pendulum can store energy. The pendulum acts as a hidden parameter of the system. The influence of the embarked pendulum in the dynamic behavior of the system is investigated and it is shown how it can affect the solutions of the dynamic equations.

가슴 착용형 보행 재활로봇의 개발

This paper describes the development of a chest-wearable robot that can efficiently perform self walking rehabilitation without a helper. The features of the developed robot are divided into three parts. First, as a mechanical characteristic, the conventional elbow crutch is attached at the forearm. However, the proposed robot is attached to the patient's chest, enabling them to feel free to use their hands and eliminate the burden of the arms. Second, as a characteristic of the driving algorithm, pressure sensors attached to the chest automatically perceive the patient's walking intention and move the robot-leg thereafter. Also, for safety, it stops operating when an obstacle is found in front of the patient by using ultrasonic sensors and generates a beeping sound. Finally, by using the scotch yoke mechanism, supporting legs are moved up and down using a rotary servo motor without excessive torque that is generated by large ground reaction forces. We showed that the developed robot can effectively perform self walking rehabilitation through walking experiments, and its performance was verified using Electromyograph (EMG) sensors.

A02 太陽熱発電システムの評価に用いる200Wスターリングエンジン発電機の開発(スターリングエンジン・熱音響エンジン)

Research of an energy system corresponding to ZEH (Zero Energy House) is advanced so as to aim at reduction of the energy consumed in domestic use. The authors are developing a hybrid heat source Stirling engine CHP (combined heat and power) system, which uses solar and woody biomass for a heat source and supplies power generation and warm water. This paper describes a development of a 200W Stirling engine generator driven by solar energy using a solar collector made by a Fresnel lens. It has an α (2-piston) type structure operated by a Scotch yoke mechanism and now is made experimentally.

Multi-Function Operating Machine: A Conceptual Model

This paper presents the concept of Multi-Function Operating Machine mainly carried out for production based industries. Industries are basically meant for Production of useful goods and services at low production cost, machinery cost and low inventory cost. Today in this world every task have been made quicker and fast due to technology advancement but this advancement also demands huge investments and expenditure, every industry desires to make high productivity rate maintaining the quality and standard of the product at low average cost. We have developed a conceptual model of a machine which would be capable of performing different operation simultaneously, and it should be economically efficient .In this machine we are actually giving drive to the main shaft to which scotch yoke mechanism is directly attached, scotch yoke mechanism is used for sawing operation. On the main shaft we have use bevel gear system for power transmission at two locations. Through bevel gear we will give drive to drilling centre and grinding centre. The model facilitate us to get the operation performed at different working centre simultaneously as it is getting drive from single power source. Objective of this model are conservation of electricity (power supply), reduction in cost associated with power usage, increase in productivity, reduced floor space.

The rolling scotch yoke mechanism applied to a small air compressor for oil-free operations

The rolling scotch yoke mechanism (RSYM), a variation of the scotch yoke mechanism, is developed in this work. The RSYM is not a mechanism by rigorous definition because the output position is not uniquely determined by the input position, however has several advantages over other reciprocating mechanisms. Unlike a conventional scotch yoke mechanism whose crank pin slides relative to the yoke, the bearing wrapping crank pin of the RSYM rolls without slipping on the yoke in the most range of operation except two small intervals where it slips. Because the friction force is very small in these brief slip intervals, the mechanism generates a much smaller amount of heat than the conventional scotch yoke mechanism. This enables the RSYM to operate in an oil-free condition while retaining all advantages of the scotch yoke mechanism. A double-cylinder air compressor for an oil-free operation was constructed by adopting the RSYM and tested to demonstrate practicality of the design.

Numerical and Experimental Investigations of JetImpingement on a Periodically Oscillating-Heated FlatPlate

Abstract: In the present paper, the impingement of air jet on a heated flat platesubjected to a periodic oscillation is numerically and experimentally investigated.The motivation of the present research is the desire to enhance the heat transfercharacteristics during the cooling process of a heated flat plate which can be foundin many relevance industrial applications. In order to improve the heat transfercharacteristics, a novel idea is utilized, where a periodical oscillation movementin form of sine wave produced from a Scotch yoke mechanism is applied to theheated flat plate. The obtained numerical results showed a good agreement withthe performed experimental measurements. Moreover, an increase of the Nusseltnumber is obtained from an oscillated plate in comparison with that obtained froma fixed plate. This reveals the enhancement of the heat transfer characteristics of aheated flat plate as a result of the applied periodic oscillation movement.Keywords: Numerical simulation, Experimental measurements, Jet impingement,heat transfer, periodically oscillating flat plate, turbulence modeling.1 IntroductionRecently, the technology of jet impingement cooling of heated surfaces has re-ceived a great attention due its heat transfer effectiveness in many industrial andengineering applications, such as: cooling of photovoltaic cells [Royne and Dey(2004)], electronics cooling [Narumanchi, et al. (2003)], steel making process[Viskanta and Incropera (1990)], cooling of gas turbine blades [Liu and Feng (2011)],and even in food-processing operations [Sarkar, et al. (2006)]. Consequently, ex-tensive researches have been carried out over several decades to explore the thermo-

Flexoelectricity of a calamitic liquid crystal elastomer swollen with a bent-core liquid crystal

We have measured the electric current induced by mechanical distortion of a calamitic liquid crystal elastomer (LCE) swollen with a low molecular weight bent-core nematic (BCN) liquid crystal, and have determined, for the first time, the bend flexoelectric coefficient e3 of such a BCN-LCE composite. In one method, we utilise air-pressure to induce a mechanical bend deformation and flexoelectric polarization in a BCN-LCE film, and then measure the polarization current as a function of time. An alternative technique uses a rotary-motor driven scotch yoke to periodically flex the BCN-LCE; in this case, the magnitude and phase of the induced current are recorded via a lock-in amplifier. The flexoelectric coefficient, e3, was found to be ∼20 nC/cm2, and is stable in magnitude from room temperature to ∼65 °C. It is about one third the value measured in samples of the pure BCN; this fraction corresponds closely to the molar concentration of BCN in the LCE. The flexoelectric current increases linearly with the magnitude of the bend deformation and decays with frequency. These observations indicate a promising way forward towards producing very low-cost, self-standing, rugged electromechanical energy conversion devices.

Tandem design of mechanisms for function generation and output speed variation

A new approach for generation of functions based on application of a multi-gear drive is proposed. The approach provides solution to the functional ψ ( α ) = g n ( g n - 1 ( ⋯ ( g 1 ( α ) ) ) ) wherein ψ ( α ) is the function assigned for generation and g i ( α ) , i = 1 , … , n , is the transmission function of pair i of conjugated non-circular gears. The specifics characteristics of the proposed approach are: (a) integrated impact by application of n synchronized gear drives, (b) favourable shape of centrodes, and (c) observation of limits of pressure angle. In addition to the approach for function generation, tandem design for the following types of planar linkages has been developed: double-crank linkage, crank-slider linkage and Scotch–Yoke mechanism. Tandem design for mechanism formed by a rack and non-circular gear has been developed as well. The developed theory is illustrated with seven detailed numerical examples.

Fretting wear studies on diamond-like carbon coated Ti–6Al–4V

This work is concerned with the performance of diamond-like carbon (DLC) coated Ti–6Al–4V flat samples fretted against alumina ball in two environments—ambient air and simulated body fluid (Ringer solution). Hydrogenated DLC (H-DLC) coatings were prepared by radio frequency plasma enhanced chemical vapour deposition process. Raman scattering measurements were done on the coatings. Fretting wear tests were conducted at different normal loads using a fretting wear test rig working on scotch yoke mechanism. Wear scars on the tested specimens were observed using an optical microscope. Wear volume was calculated based on wear scar diameter measured along parallel and perpendicular to the fretting direction. Tangential force coefficient (TFC) values exhibited by DLC coated samples were lower than those exhibited by uncoated specimens in both ambient air and Ringer solution. Very low TFC values and low wear volume were observed for H-DLC coated samples tested in air at lower loads of 1.9 N and 4.9 N. It was attributed to occurrence of graphitisation and formation of transfer layer on alumina ball.

Dolphin-like propulsive mechanism based on an adjustable Scotch yoke

This paper addresses the design, construction, and motion control of an adjustable Scotch yoke mechanism generating desired kinematics for dolphin-like robots. Since dolphins propel themselves by dorsoventral oscillations following a sinusoidal path with alterable amplitudes, a two-motor-driven Scotch yoke mechanism is adopted as the primary propulsor to produce sinusoidal oscillations, where a certain combination of a leading screw mechanism and a rack and pinion mechanism driven by the slave motor are incorporated to independently change the length of the crank actuated by the master motor. Meanwhile, the output of the Scotch yoke, i.e., reciprocating motion, is converted into the up-and-down oscillations via a rack and gear transmission. A DSP-based built-in motion control scheme is then brought forth and applied to achieve dolphin-like propulsion. Preliminary tests, in a robotics context, confirm the feasibility of the devised mechanism severing as a dedicated propulsor for bio-inspired movements.

D02 スコッチヨーク機構を用いたβ型スターリングエンジンの再生器特性(再生熱交換器の基本特性)

A β type Stirling engine which used a scotch yoke mechanism was made. This engine installed a regenerator into displacer piston for minimizing a dead space of fluid path. The mechanical loss of the engine was investigated at room temperature. For reducing the mechanical loss due to friction, several kinds of lubricant oil were tested. The influence of pore size of regenerator was made clear experimentally.

Two-dimensional lubrication analysis and design optimization of a Scotch Yoke engine linear bearing

Recent study has shown that the application of a Scotch Yoke crank mechanism to a reciprocating internal combustion engine reduces the engine's size and weight and generates sinusoidal piston motion that allows for complete balance of the engine. This paper describes detailed investigation of the performance of a linear bearing assembly, which is one of the key components of the Scotch Yoke mechanism. The investigation starts by solving Reynolds equation for the Scotch Yoke linear bearing. The two-dimensional lubricant flow is numerically simulated and the calculated results are compared with experimental results from a linear bearing test rig. The performance characteristics and a design sensitivity analysis of the bearing are presented. Dynamic testing and analysis of an instrumented linear bearing on a test rig are used to validate the numerical simulation model. The oil supply and lubrication mechanism in the linear bearing are analysed and described in detail. This work aims to provide new insights into Scotch Yoke linear bearing design. In addition, strategies for optimization of the linear bearing are discussed.

Insect-like flapping wing mechanism based on a double spherical Scotch yoke.

We describe the rationale, concept, design and implementation of a fixed-motion (non-adjustable) mechanism for insect-like flapping wing micro air vehicles in hover, inspired by two-winged flies (Diptera). This spatial (as opposed to planar) mechanism is based on the novel idea of a double spherical Scotch yoke. The mechanism was constructed for two main purposes: (i) as a test bed for aeromechanical research on hover in flapping flight, and (ii) as a precursor design for a future flapping wing micro air vehicle. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a "figure-of-eight" or a "banana" and the wing changes the angle of attack (pitching) significantly. The kinematic and aerodynamic data from free-flying insects are sparse and uncertain, and it is not clear what aerodynamic consequences different wing motions have. Since acquiring the necessary kinematic and dynamic data from biological experiments remains a challenge, a synthetic, controlled study of insect-like flapping is not only of engineering value, but also of biological relevance. Micro air vehicles are defined as flying vehicles approximately 150 mm in size (hand-held), weighing 50-100g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application, insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Since the semi-span of the insect wing is constant, the kinematics are spatial; in fact, an approximate figure-of-eight/banana is traced on a sphere. Hence a natural mechanism implementing such kinematics should be (i) spherical and (ii) generate mathematically convenient curves expressing the figure-of-eight/banana shape. The double spherical Scotch yoke design has property (i) by definition and achieves (ii) by tracing spherical Lissajous curves.

Speed Control of a 2-DOF Reciprocating Machine Using a Virtual-Vibration-Absorber Algorithm

A two-axis reciprocating machine, termed Complementary Scotch Yoke (CSY), is regulated via a novel control algorithm. Containing two independent driving motors, it is capable of converting two-axis rotary movements into double-mode linear harmonic motions. The axes are subject to periodic disturbances of quadruple characteristic frequencies when the machine undergoes harmonic motions. A feedback law emulating multi-mode vibration absorbers is designed to compensate for the periodic disturbances so that the driving axes are regulated at the set angular speeds. The virtual passive controller ensures stability of the unforced system, and it is shown that the periodic disturbances can be canceled out if the virtual vibration absorber has all of the characteristic frequencies of the disturbance. Experimental results on a CSY prototype confirm the effectiveness of the proposed method.