LOW NOISE BLOWER FAN

Description

1. FIELD OF THE INVENTION

The present invention relates to a blower fan, and particularly to a blower fan which has low noise.

2. DESCRIPTION OF RELATED ART

Vibration of blower fans due to rotor imbalance is noisy. If the vibrations are of a high frequency and have a large amplitude, a fairly loud noise can be produced. This noise may become annoying to users of a device with such a blower fan.

Referring to FIG. 5, a conventional blower fan is shown. A case of the blower fan includes a base plate 20, and a bearing set 40 extends upwardly from the base plate 20. A pair of ball bearings 10 is supported by the bearing set 40. A shaft 50 is supported by the ball bearing 10. A sealing plate 30 is mounted on the base plate 20. Vibration of the shaft 50 is transmitted to the base plate 20 via the ball bearings 10, then to the sealing plate 30. If the sealing plate 30 and the base plate 20 have large amplitude vibrations, noise is produced. FIG. 6 is a graph showing noise characteristics of the conventional blower fan shown in FIG. 5. A peak noise level is nearly 40 dB.

What is needed is a blower fan that produces less noise.

SUMMARY OF THE INVENTION

An exemplary low noise blower fan includes a base plate for supporting a rotating shaft and a bearing. The shaft is rotated in the bearing. A pad made of damping material is attached to the base plate to dampen vibrations.

It is simple and economical to employ a damping pad to dampen vibrations thereby suppressing noise of the blower fan.

Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded isometric view of a blower fan in accordance with a preferred embodiment of the present invention, the blower fan including a pad;

FIG. 2 is an assembled cutaway view of the blower fan of FIG. 1;

FIG. 3 is a graph showing noise characteristics of the blower fan when the pad of FIG. 1 is made of bitumen;

FIG. 4 is a graph showing noise characteristics of the blower fan when the pad of FIG. 1 is made of composite materials;

FIG. 5 is a cutaway view of a conventional blower fan; and

FIG. 6 is a graph showing noise characteristics of the conventional blower fan of FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1 and 2, a case of a blower fan in accordance with a preferred embodiment of the present invention includes a base plate 100, and a sleeve 300 extending up from the base plate 100. A pair of ball bearings 400 is supported by the sleeve 300. A shaft 500 is supported by the ball bearings 400. The base plate 100 defines a recess in a surface, a sealing plate is received in the recess. The sealing plate 100 encloses one end of the sleeve adjacent the base plate 100. A pad 600 which is made of damping material is attached to the base plate 100 and covers the sealing plate 200. The pad 600 is pasted on the base plate 100 using glue. The sealing plate 200 is sandwiched between the base plate 100 and the pad 600. Vibration of the shaft 500 is transmitted to the base plate 100 via the ball bearings 400, then to the sealing plate 200, noise is generated mostly due to the vibration of the base plate 100 and the sealing plate 200. The pad 600 is capable of absorbing vibrations because of the energy-absorbing capacity of the elements constituting the pad 600. It is preferred that the pad 600 should cover most of the surface area of the base plate 100 of the case of the blower.

FIG. 3 is a graph showing noise characteristics of the blower fan when the pad 600 is made of bitumen. It can be seen that peak noise level is no higher than 20 dB. In FIG. 6, which depicts noise characteristics of a conventional blower fan, peak noise levels exceed 35 dB.

FIG. 4 is a graph showing noise characteristics of the blower fan when the pad is made of composite materials. It can be seen that peak noise level is less than 30 dB. Employing the pad 600 made of damping materials reduces noise of the blower fan.

The material of the pad 600 is not limited.

It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.