Hydrodynamic bearing device, and spindle motor and information apparatus equipped with same

A hydrodynamic bearing device, comprising:

• a shaft;
• a sleeve that has a bearing hole wherein the shaft is mounted in said bearing hole in a state of being capable of relative rotation;
• a first gap that is formed between the shaft and the bearing hole of the sleeve;
• a communicating path that is formed in part of the sleeve and allows communication between an open end side and a closed end side of the bearing hole in the sleeve;
• a first hydrodynamic groove that is formed in the outer peripheral surface of the shaft and/or the inner peripheral surface of the bearing hole of the sleeve;
• a sleeve cap that is provided on an open end side of the sleeve and has a center hole;
• a substantially circular second gap that is formed between the sleeve cap and the end surface on the open end side of the sleeve, and forms a lubricant reservoir;
• a thrust bearing member that is fixed to the open end side of the shaft and is disposed so as to be near the inner peripheral surface of the center hole of the sleeve cap;
• a third gap that is formed between the outer periphery of the thrust bearing member and the inner peripheral surface of the center hole of the sleeve cap, and is open to the atmosphere;
• a fourth gap that is formed between the thrust bearing member and the end surface of the sleeve;
• a lubricant that accumulates in the first gap, the communicating path, the second gap, and the fourth gap, wherein the first gap, the communicating path, the second gap, and the fourth gap communicate with each other;
• and
• a circulation passage that includes the communicating path, the first gap, and the second gap, wherein the lubricant circulates through said circulation passage.