Rolling bearing for inverter-driven motor and inverter-driven motor therewith

Abstract

A rolling bearing for an inverter-driven motor has the thickness of an oil film in a steady operation condition stably maintained in a specific range, by which the withstand voltage can be controlled, and the discharge due to the shaft voltage of the inverter-driven motor is prevented and electrolytic corrosion can be suppressed. The rolling bearing for an inverter-driven motor has an inner ring, an outer ring, a rolling element, and grease, wherein a root mean square roughness of a raceway surface of at least one of the inner ring and the outer ring is 4 to 16 nm, and an oil film parameter [Lambda] in steady operation is at least 17.5.

Description

technical field [0001] The present invention relates to a rolling bearing capable of suppressing electric corrosion for use in an inverter-driven motor such as an air conditioner motor, and an inverter-driven motor using the rolling bearing. Background technique [0002] In recent years, a pulse width modulation (Pulse Width Modulation) method (hereinafter, referred to as a PWM method) driven by an inverter is often used for motors. In such a PWM-based inverter drive, since the neutral point potential of the winding is not zero, a potential difference (hereinafter referred to as shaft voltage) may be generated between the outer ring and the inner ring of the bearing. This shaft voltage contains high-frequency components caused by commutation. When the shaft voltage reaches the insulation breakdown voltage of the oil film inside the bearing, a small current flows inside the bearing, thereby generating discharge between the inner and outer rings of the bearing and the rolling ...

AI Technical Summary

Problems solved by technology

[0007] However, in the technique of providing the discharge brush, when the conductivity is impaired due to the wear of the discharge brush, there is a problem that the resistance of the discharge brush is higher than the resistance between the inner and outer rings and the rolling elements, and the resistance between the inner and outer rings is higher than that between the inner and outer rings. The problem of re-starting of energization; the problem of damage inside the bearing due to the wear powder generated from the discharge brush

In addition, in the technology of making the contact surface of the inner and outer rings and rolling elements rough and easy to discharge, measures are taken to avoid large damage to the raceway surface by frequent and repeated small discharges, but no matter how small the discharge is, it may cause damage to the raceway surface. The roughness of the contact surface becomes larger, which eventually leads to the problem of reduced bearing life

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