Shigeo Ikai

Thrust bearing using a magnetic fluid lubricant under magnetic fields

Abstract This paper describes a thrust bearing using a magnetic fluid lubricant under a magnetic field. The critical pressures of the bearing versus the magnitude of the magnetic flux densities have been investigated experimentally. It is shown that the critical pressures of the proposed bearing are larger than those of the normal lubricated bearing under high speeds.

A torque-controllable electromagnetic multiple-disc brake

Abstract This paper describes a new type of electromagnetic multiple-disc brake for controlling braking torque. The brake consists of a rare-earth permanent magnet, an electromagnet and multiple friction discs. The friction torque is controlled by the electric current in a coil of the electromagnet. In the analysis the design formulae for the brake are first derived from electromagnetic theory and tribological considerations, then the transient braking torque under the electric current control is derived and vibrations of the disc considered. To verify the present system and the analysis, experimental tests were made on the brake.

Steady state responses of a relaxation-suspension system with unsymmetrical damping force.

This paper presents theoretical and experimental results for the steady state response of a relaxation-suspension system considering the unsymmetrical damping force under periodic excitation. the unsymmetrical damping force has two different values in period of the stroke velocity. In the analysis, exact solutions are obtained by considering the continuity of the response at the boundary in which the damping force varies. Numerical calculations are carried out for various values of the ratio of the damping coefficient. It is found that the reference line of the vibration in the relaxation-suspension system maintains a constant value within the range of the high frequency ratio, while the reference line in the direct-suspension system varies proportionally to the change of frequency ratio. The experimental values agreed fairly well with the theoretical results.

Measurement of masses of magnetic particles in a fluid with low density. A method using a laser and NMR.

This paper is concerned with a method for measuring masses of the magnetic particles in a fluid such as a magnetic fluid. Two methods are proposed, one of which is the phase difference procedure by use of a laser, and the other is the nuclear magnetic resonance (NMR) procedure. Experimental tests have been carried out to find masses of the magnetic particles in the magnetic fluid with various densities by using the methods mentioned above. It is clarified that the present methods are applicable to measure the masses in a fluid, including a few particles.

Dynamic transmission torque of a flexible multiple-disc clutch and brake to intermittent loads

Abstract This paper is concerned with a transmission torque of a flexible multiple-disc clutch subjected to dynamic loads. The analysis has been developed on the problem of the clutch subjected to a dynamic load which varies as a half-rectified sine function with time. In the analysis, the elastodynamic theory of a circular plate has been extended to this problem by application of the Laplace transform method. The dynamic pressures and the reaction forces along the edge between discs have been obtained from the conditions of continuity between discs, and from which the transmission torque of the clutch has been concluded. Numerical results of the transmission torque versus time and the deflections and bending moments in the clutch have been given for some important cases