As is well known, fluid dynamic bearing devices have features in, for example, their high speed rotation, high rotational accuracy, and quietness. Thus, the fluid dynamic bearing devices are suitably used as bearing devices for motors to be mounted to various electrical apparatus such as information apparatus, for example, as bearing devices for spindle motors to be built in disk drives such as HDDs, for fan motors to be built in PCs and other devices, or for polygon scanner motors to be built in laser beam printers (LBPs).
For example, in Patent Literature 1, there is disclosed a fluid dynamic bearing device (spindle motor) including a bearing sleeve made of sintered metal, a rotary member including a shaft portion inserted along an inner periphery of the bearing sleeve, and a hub portion arranged on an axially outer side with respect to one end surface of the bearing sleeve, and a radial bearing portion and a thrust bearing portion configured to support the rotary member in a non-contact manner respectively in a radial direction and a thrust direction. Along with rotation of the rotary member, a radial bearing gap of the radial bearing portion is formed between an inner peripheral surface of the bearing sleeve and an outer peripheral surface of the shaft portion opposed to the inner peripheral surface of the bearing sleeve, and a thrust bearing gap of the thrust bearing portion is formed between the one end surface of the bearing sleeve and an end surface of the hub portion opposed to the one end surface of the bearing sleeve. In this fluid dynamic bearing device, the bearing sleeve is fixed to an inner periphery of a housing having a bottomed cylindrical shape. An opening portion of the housing is formed between an outer peripheral surface of the housing and an inner peripheral surface of the hub portion, and is sealed by a sealing gap that retains an oil surface of lubricating oil. With this configuration, leakage of the lubricating oil to an outside can be prevented as much as possible, thereby being capable of stably maintaining desired bearing performance.