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Brushless motor having lubrication system for upper and lower bearings
| Details |
Inventors: Ohi, Shinichi; Umegaki, Fuhito; Takemasa, Masami; Haraguchi, Tatsuo; Gunji, Yoshihide; Ohsawa, Hiroshi;
Assignee: Zexel Corporation (Tokyo, JP)
Primary Examiner: Dougherty; Thomas M.
Assistant Examiner: Jones; Judson H.
Attorney, Agent or Firm: Wenderoth, Lind & Ponack
The present invention offers a simple structure that facilitates the mounting of bearings, that maintains lubricating oil at a sufficient level in the bearing portions and that maintains an optimal distance between a rotor and a case housing for preventing freezing, for preventing reduction of the capacity and for preventing noise. Bearing stoppers provided between the bearings of the brushless motor and the bearing holders, which hold the upper end edge of each bearing, are secured at a projection formed at the internal circumferential surface of each bearing holder. A felt, which comes in contact with the lower portion of each bearing stopper and also comes in contact with the bearing at one side is provided, with holes communicating with the felt formed at the lower surface of the bearing stopper. In addition, the lower limit of the distance h between the lower end of the rotor and the upper end surface of the case housing is set at 1.5 mm. This prevents water from forming a connection between the rotor and the case housing due to capillary action and surface tension. In addition, the upper limit of the distance h is set at or under 8 mm, which represents the critical point for the capacity and the noise. This ensures that the capacity is maintained at a satisfactory level and also prevents noise from increasing. Moreover, a washer group, which comprises at least one each of a resin washer, a rubber washer and a POM (polyoxymethylene) washer is provided between a sensor magnet that is secured to the lower end of the rotating shaft and the lower bearing. |
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DETAILED DESCRIPTION Accordingly, a first object of the present invention is to provide a brushless motor with a simple structure that facilitates the mounting of bearings and allows lubricating oil to be maintained at a sufficient level at the bearing portions.
Thus, according to the present invention, in a brushless motor comprising a rotating shaft, bearings that support the rotating shaft rotatably, bearing holders that hold the bearings, a rotor that is secured to the rotating shaft, a permanent magnet provided circularly at the rotor, a stator that generates a rotating magnetic field at the permanent magnet, an excitation coil that is wound around the stator, a control circuit board in which an excitation circuit for applying power to the excitation coil is wired and a case housing in which the control circuit board is housed, a bearing stopper is provided between each bearing and bearing holder to hold the upper end edge of the bearing, secured by a retaining claw formed on the internal circumferential surface of the bearing holder.
With this, after mounting the bearing in the bearing holder, the bearing can be held by mounting the bearing stopper at the bearing holder, making it possible to reduce the number of steps required for mounting the bearing.
In addition, according to the present invention, a felt is provided to come in contact with the lower portion of the bearing stopper with its inner surface in contact with the bearing, and in the lower surface of the bearing stopper, a hole is formed that communicates with the felt.
This allows the lubricating oil spattered from the upper end portion of the bearing in the direction of the radius to be collected in the bearing stopper and allows it to be supplied to the felt via the hole formed in the bearing stopper.
As a result, lubricating oil can be replenished to the bearing through this felt, making it possible to maintain the quantity of lubricating oil at the bearing at a constant level at all times.
Moreover, an oil guide which inclines gradually downward toward the outside in the direction of the radius may be provided, for instance, at the lower end surface of a component provided at the upper portion of the bearing, i
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Generators or Motors 
