• Tribology and Lubricants
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• 제3권2호
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• pp.72-80
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• 1987

A planocentric torque driver comprises a stationary internal gear with the teeth of a circular concave profile and an external gear of an epitrochoid curve. The contact mechanism of the teeth is examined and analyzed by means of computer simulation. Analyses of load variation on the tooth and strength of appliance is carried out. And the output device is examined. Finally, the design of a 59:1 reduction ratio torque driver is presented.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 B
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• pp.785-787
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• 1999

In this paper, recursive least square algorithm is presented to estimate the parameters of step motor under low-speed operation. Parameter estimation is important for compensating the input current by calculating the ratio of the motor torque constant and detent torque constant that causes torque-ripple in low-speed applications. On-line parameter estimation process is a preliminary procedure to apply step motor to adaptive control. Computer simulation shows that the estimated parameters converge in finite time.

• 오토저널
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• 제9권6호
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• pp.53-59
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• 1987

The effect of the three types of fuel vaporizing device on the engine torque and exhaust emission was investigated. Among the three types of fuel vaporizing device designed for the experiments, a 88mm long device with mesh around the inside pipe showed stable lean mixture combustion up to 21:1 air-fuel ratio and reduced the exhaustion of CO and HC. Compared with the general trend in the decrease of engine torque it was observed that the decrease of engine torque in this lean mixture combustion with the new device was small.

• 연구논문집
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• 통권33호
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• pp.53-65
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• 2003

Electrostatic micro-motors can be divided into three classes: (i) salient type side drive motor, (ii) radial gap type wobble motor, (iii) axial gap type wobble motor. The working mechanism, torque evaluation, fabrication, and operational characteristics of each micro motors are compared. It is proved that axial gap type wobble motor has the bigger generating torque than that of the other type. The gear ratio of wobble motors increases the driving torque at the cost of a decreasing angular speed and decreases the friction because of the rolling motion instead of sliding at the bearing. Techniques for characterizing micro-motors performance are presented.

• 소음진동
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• 제7권4호
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• pp.613-620
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• 1997

Steady and unsteady flows between rotating cylinders are of interest on lubrication, convective heat transfer and flow-induced vibration in large rotating machinery. Steady rotating flow is generated by rotating cylinder with constant velocity while the unsteady rotating flow by oscillating cylinder with homogeneoysly oscillating velocity. An analytical method is developed based on the simple radial coordinate transformation for the steady and unsteady rotating flows in concentric annulus. The governing equations are simplified from Navier-Stokes equatins. Considering the skin friction based on the radial variation of circumferential flow velocity, the torques acting on the fixed and the rotating cylinder are evaluated in terms of added-inertia and added-damping torque coefficients. The coefficients are found to be influenced by the oscillatory Reynolds number and the radius ratio of two cylinders; however, the effect of the oscillatory Reynolds number on the coefficients is minor in case of relatively low radius ratio.

• 한국정밀공학회지
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• 제14권3호
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• pp.35-40
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• 1997

The traction drive has advantages of having high efficiency and transmitting the power without blacklash. However, when high ratio of speed reduction is desired, excessively large size is required. In this study, a new type of traction drive is invented, designed and manufactured so that stable speed reduction mech- anisms are available by adopting a cross roller type drive. It has a simple structure, but produces high speed reduction ratio. Power loss is observed, and also, driving torque and torque transfer efficiency are calculated. Pre-loads are needed in order that the traction drive transfers power without slipping, and the spacer is enlarged due to the pre-loading. After all, the key point of pre-load mechanism is that the spacer's diameter becomes larger as pre-loads are applied.

• Journal of Mechanical Science and Technology
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• 제16권5호
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• pp.639-646
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• 2002

In this paper, thrust equations for a rubber belt CVT are derived by considering the geometry and mechanism of the mechanical actuators. In order to solve the thrust equations, an algorithm to calculate the speed ratio is suggested for the given driver speed and load torque based on the actuator characteristic equations and existing formula for the belt thrust forces. Experiments are performed to investigate the driver speed-load torque-speed ratio characteristics at a steady state. The speed and torque efficiencies are measured and used to modify the actuator equations. It is found that the modified equations well predict the steady state characteristics. In addition, the shift dynamic model for a rubber belt CVT is derived experimentally. Simulation results of the CVT shift dynamics are in good accordance with the experiments and it is noted that different coefficients are required to describe the CVT shift dynamics for the upshift and the downshift.

• 대한기계학회논문집B
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• 제24권4호
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• pp.561-569
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• 2000

The purpose of this study is to construct a testing equipment with which several characteristics of the domestically developed swashplate type axial piston motor can be tested and to develop a software with which the data from experiment can be stored and can be applied. The results of the study are as follows; 1) The leakage flow and the torque of the motor being stopped is propotional to supply pressure and their relation can be showed by linear equations. 2) The motor movement is not smooth below 50 rpm but it moves smoothly up 170 rpm. 3) When the motor starts or stops, the pressure rise ratio effects decisively to the max. torque.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.9-11
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• 1999

This paper presents the problems of design and theoretical model of electrostatically driven axial-gap type wobble motor. The motor design benefits from large axial rotor-to-stator overlap and large gear ratios, and motor designs with rotor radii of 50 and $100{\mu}m$ are capable of generating torques in the [nNm] range at high electrostatic fields. Because of the large gear ratio, smaller angular steps and lower rotational speed are obtained, compared to radial-gap motor design. Aspects like gear ratio, torque generation, excitation schemes and torque coverage, normal forces, friction are addressed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.753-754
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• 2006

In case of the synchronous reluctance motor, the torque is proportional to silency difference and the power factor is in proportion to silency ratio. This paper presents the rotor design variable that has a effect on silency difference and silency ratio for getting a maximum torque and a power factor in the synchronous reluctance motor. To carry through the object, a number of the analysis model is reduced by DOE (Design of Experiments) and the main effects are found by the FEM (Finite Element Analysis).