Kazumi Ishikawa

A Novel Cableless Magnetic Actuator Capable of Reversible Motion in a Thin Pipe

This paper proposes a new type of a cableless magnetic actuator that exhibits a high speed locomotion and considers reversible motion of the cableless actuator due to control of a magnetic field by using coils outside a pipe. This actuator contains a mechanical inverter that directly transforms dc from button batteries into ac. The mechanical dc-ac inverter incorporates a mass-spring system and a curved beam with a concentrated mass that switches under an electromagnetic force. The actuator is moved by inertia force of the mass-spring system due to mechanical resonance energy. Experimental result shows that the actuator is able to move upward at a speed of 16.5 mm/s by using 10 button batteries when pulling 10 g load mass. The results hold great promise for the creation of highly mobile actuator capable of moving in pipes with diameters of under 8 mm.

Design of outer-rotor-type multipolar switched reluctance motor for electric vehicle

In an electric vehicle (EV) with in-wheel motors, reducing the weight of the motor is a very important problem in order to improve the driving performance. In this paper, we examine the lightweight design of an outer-rotor-type multipolar switched reluctance (SR) motor applied to a prototype EV. We design three SR motors which have different yoke widths and calculate the motor characteristics at a steady rotational speed based on a finite element method. We discuss the optimum relationship between a pole and yoke widths.

Performance characteristics of a new type of linear parametric motor with double driving surfaces

This paper describes the structure and the performance characteristics of a new type of linear parametric motor with double driving surfaces. The static thrust Fs of the linear motor is larger than nearly 1.5 times and the thrust-to-mass ratio (Fs/M) is improved by approximately 1.65 times compared to values for a 4-legged linear parametric motor.

A new type 4-legged linear parametric motor with excellent performance

This paper describes the operating principle and the basic characteristics of a new type of linear parametric motor which eliminates a part of the magnetic circuit of the 4-legged linear parametric motor. A double-sided linear motor using the new type of linear parametric motor has an improved thrust-to-mass ratio because part of the magnetic circuit has been eliminated.

Improvement of the performance characteristics of a linear parametric motor with open magnetic circuit

This paper describes the structure and the performance characteristics of a linear parametric motor with open magnetic circuit. The static thrust Fs is increased approximately 17% by placing an iron plate having the most suitable dimensions on the magnetic poles.

Some Considerations on the Directional Control of a Linear Parametric Motor

This paper describes two methods for the directional control of a linear parametric motor. The first uses a circuit-changing switch. The direction of this linear parametric motor can be controlled by exchanging the power supply circuit and tuning the capacitor circuit. In the second method, which we call separately excited control, the linear motor has two power supplies, and the velocity or direction of the mover can be easily controlled by regulating the primary voltage phase difference. The experimentally ascertained features of these two methods are described.

Impedance Measurement Using a Resonance Circuit for Detecting Steel Bars and Cables Inside Pliable Plastic Conduit Tubes Buried in Concrete Walls and Slabs

In order to detect steel bars and power cables inside pliable plastic conduit tubes buried in concrete walls and slabs during the renovation of old buildings, we have developed a new nondestructive inspection (NDI) system. This system, which enables high precision detection and easy handling at low cost, works by measuring the impedance due to the inductance change of a solenoid coil which exposes the test material to a magnetic field. In this system, the solenoid coil is connected to a compensating capacitor with a series-resonant circuit to reduce the impedance and multiply the impedance change by increasing the quality factor, Q, i.e., the ratio of the inductive reactance, ?L, to the coil resistance, R, which contributes to improving the signal-to-noise ratio for detection. This paper describes the validity of the design method of this NDI system. Firstly, the fractional deviation of inductance, ?, the inductance changes between with and without a steel bar and power cables were analyzed. The deviations due to the eddy currents and magnetization induced in the steel bars and power cables were computed through 3-D magnetic field analysis taking eddy currents at 5, 40 and 800 kHz into account. Secondly, the rates of change of impedance (RCIs) and phase angles were measured with the impedance meter of the newly developed NDI system. This system was designed so that the value of became roughly 200 and the resonance frequencies became about 5, 40 and 800 kHz. For steel bars, the predicted RCIs, which were calculated from the computed s multiplied by the designed Q factor, roughly matched those measured. In case of power cables, the tendency of predicted RCIs were roughly in accord with those measured. The validity of the design methods detecting system was verified. In addition, the analysis and measurement proved that this NDI system can distinguish steel bars from power cables by the polarity of the phase angle.

On the Air Gap Flux-Density Distribution and Characteristics of Linear Parametric Motors

The structure and operation of a four-legged linear parametric motor include such excellent features as a very simple construction and negligible operating maintenance. We calculated the performance characteristics of such linear motors numerically, using a two-dimensional static field analysis program, and obtained the flux density distribution in the gap. We here show that the performance characteristics of four-legged linear parametric motors can be improved by decreasing the thickness at the center of the common magnetic circuit.

Dynamic Pipe Fracture in Water Pipeline

In the case of sudden valve closure waterhammer creates the most powerful pressure and damage to pipeline systems. The best way to protect the pipeline system is to eliminate waterhammer. The main reasons of waterhammer occurrence are valve closing, initial velocity, and static pressure. However, it is not always so easy to eliminate waterhammer. More or less, waterhammer occurs when the valve is being closed. In this study the pipe fracture caused by static water pressure, gradually increased pressure, and suddenly increased pressure are compared experimentally in a breaking PVC test pipe. The classification of the quasi-static zone, the dynamic zone, and the impact zone are shown in the results of those experiments by considering the fracture patterns of test pipes and impulse. The results of the maximum pressure are used to design the pipeline even though it is in the dynamic zone. The impact zone is shown in this study, which is influenced by not only the dynamic characteristics of pipe materials but also by the acceleration term of the momentum equation.

Improvement of moving characteristics of cableless micro-actuator and consideration of reversible motion

We previously proposed a novel cableless micro-actuator that provides propulsion using the mechanical resonance energy of a system excited by an electromagnetic force. However, it was possible for that the actuator to move only one direction and comparative low speed locomotion. This paper proposes a cableless micro-actuator that exhibits a high speed locomotion and considers reversible motion of the cableless actuator due to control of a magnetic field by using coils outside the pipe. This actuator contains a mechanical inverter that directly transforms DC from button batteries into AC. The mechanical DC-AC inverter incorporates a one-degree-of-freedom-model and a curved beam with a concentrated mass that switches under the electromagnetic force. The actuator is moved by inertia force of the one-degree-of-freedom-model due to mechanical resonance energy. Experimental results show that the actuator can move upwards at a speed of 16.5 mm/s by using 10 button batteries when pulling 10 g load mass. The results hold great promise for the creation of highly mobile actuators capable of moving in thin pipes with diameters of under 8 mm.