JPH11257280A - Axial-flow fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize an axial-flow fan by comprising a bearing housing a small diametral cylinder part integrally formed with a circular plate-like wall part arranged in the intermediate part of an electric motor retaining cylindrical part, arranging the circuit board of the driving circuit of the electric motor on the axial outside of the small diametral cylinder part, and increasing the parts loading area of the circuit board of the driving circuit of the electric motor. SOLUTION: A circular plate-like wall part 14 is arranged in the intermediate position of the cylindrical width of an electric motor retaining cylindrical part 13 so as to be integrated with the electric motor retaining cylindrical part 13 formed in a venturi case 10. A small diametral cylinder part 15 is formed coaxially with the electric motor retaining cylindrical part 13 so as to be integrated with the circular plate-like wall part 14. The small diametral cylinder part 15 has a function as a bearing housing. As means corresponding to desired electronic parts, a circuit board 42 is additionally arranged on the right side of the circular plate-like wall part 14 retaining the small diametral cylinder part 15, as shown in figure. The circuit board 42 is arranged on an outer side in the axial direction of the end part of the small diametral cylinder part 15, therefore the conventional relief hole penetrated through the small diametral cylinder part 15 in no more required. Therefore, a loading area for electronic parts 43 is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of an axial fan suitable for reducing the size and increasing the degree of integration of components mounted on a drive circuit incorporated in the axial fan.

[0002]

2. Description of the Related Art FIG. 6 is an enlarged sectional view of a conventional axial flow fan, and FIG. 7 is a front view of FIG. Venturi case 10
Constitutes an annular wind tunnel portion by a cylindrical outer wall 11 and a motor holding cylindrical portion 13 connected to the cylindrical outer wall 11 by legs 12. A bottom wall 16 is integrally formed at one end of the motor holding cylindrical portion 13, and a small-diameter cylindrical portion 15 is formed from the center of the bottom wall 16 toward the other end of the motor holding cylindrical portion 13. The small-diameter cylindrical portion 15 has a function as a bearing box, and the venturi case 10 is provided with an impeller 20 supported by the electric motor 3 so as to be freely rotatable.

The stator 31 of the electric motor 30 is fitted and held on the inner peripheral surface of the open end at the other end of the electric motor holding cylindrical portion 13 so as to be close to the top of the stator winding 31 a of the electric motor 30. A drive circuit 40 for driving and controlling the drive circuit 30 is provided.

Since the circuit board (1) 41 constituting the drive circuit 40 is disposed on the outer peripheral side of the small-diameter cylindrical portion 15, an escape hole through which the small-diameter cylindrical portion 15 is inserted is provided at the center as shown in FIG. It is necessary to provide the circuit board 41a, so that the area for mounting the electronic component 43 on the circuit board (1) 41 is reduced. In particular, for a circuit requiring high-level control or a special function, the electronic components 43 mounted on the circuit board (1) 41 are also diversified, so that the circuit board (1) 4
1, the mounting density is inevitably increased, and although not shown, double-sided mounting with a single circuit board is also required. Usually, as shown in FIG. 6, two circuit boards (1) 41,
In addition to using 41, a large number of circuit boards were also installed.

[0005]

According to the above conventional structure, the circuit board constituting the drive circuit is usually arranged outside the cylindrical surface of the bearing box (small-diameter cylindrical portion). Since a large clearance hole to be inserted had to be provided in the center of the circuit board, the electronic component mounting area of the circuit board corresponding to the clearance hole was reduced, and both sides of the circuit board were mounted to mount required electronic components. However, even if it is mounted on a board, it is often necessary to add a circuit board. SUMMARY An advantage of some aspects of the invention is to increase the mounting area of electronic components on a circuit board constituting a drive circuit of an electric motor and to reduce the size of an axial fan.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an axial fan in which an annular wind tunnel is formed by a cylindrical outer wall and a motor holding cylindrical portion connected to the cylindrical outer wall via a plurality of legs. A disk-shaped wall portion is provided at an intermediate portion of the motor holding cylindrical portion, and a small-diameter cylindrical portion formed integrally with the disk-shaped wall portion forms a bearing box, and a drive circuit for driving the motor includes the small-diameter drive circuit. A circuit board having a circuit board disposed axially outside the cylindrical portion, or a circuit board loosely fitted to the cylindrical surface of the small-diameter cylindrical portion, and at least one circuit board disposed axially outside the small-diameter cylindrical portion; The present invention is achieved by an axial fan characterized by having a plurality of circuit boards comprising: By using the circuit board of the drive circuit based on the above configuration, the area for mounting electronic components on the circuit board can be increased, and a drive circuit suitable for mounting a wide variety of electronic components can be obtained. The overall size can be reduced.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of an axial fan according to the present invention, and FIG. 2 is a venturi case 1 shown in FIG.
0 is a sectional view.

As shown in FIGS. 1 and 2, a disk-shaped wall portion 14 is integrally formed with the motor holding cylindrical portion 13 formed on the venturi case 10 at a position approximately at the center of the cylindrical width of the motor holding cylindrical portion 13. The small-diameter cylindrical portion 15 is formed coaxially with the motor holding cylindrical portion 13 integrally with the disk-shaped wall portion 14. The small-diameter cylindrical portion 15 has a function as a bearing box, and is provided at the left open end of the motor holding cylindrical portion 13 in the drawing.
The stator 31 of the electric motor is fitted and held, and the motor 30 is inserted into the interior space forming a concave portion having a U-shaped cross section by the three members of the motor holding cylindrical portion 13, the disk-shaped wall portion 14, and the small-diameter cylindrical portion 15. And a circuit board 41 on which electronic components 42 for driving the electric motor 30 are mounted and a driving circuit 40 is mounted.

The circuit board (1) 41 disposed adjacent to the electric motor 30 is a conventional circuit board (1) shown in FIG.
As in the case of 41, an escape hole 41a is formed in the center portion to insert the small-diameter cylindrical portion 15, and is formed so as to fit loosely with the outer peripheral surface of the small-diameter cylindrical portion 15, so that an electronic component as a circuit board is mounted. As a means corresponding to a desired electronic component 43, a circuit board (2) is provided on the right side of the disc-shaped wall portion 14 holding the small-diameter cylindrical portion 15 in FIG.
42 are additionally arranged. The circuit board (2) 42
Since the end portion of the small-diameter cylindrical portion 15 is disposed outside in the axial direction, it goes without saying that the relief hole 41a at the center portion like the conventional circuit board (1) 41 shown in FIG.

Incidentally, the small-diameter hole 42a formed in the center of the circuit board (2) 42 shown in FIG. 3 avoids interference with the shaft end of the rotor 32 in the working process, and is not an essential requirement. . Thus, the electronic component 43 can be mounted up to near the center of the circuit board 42. That is,
As is apparent from comparison with FIG. 5 of the related art, in FIG. 4, the electronic component 43 indicated by hatching cannot be mounted on the circuit board (1) 41 arranged on the outer peripheral side of the conventional small-diameter cylindrical portion 15. The circuit board (2) 42 is required as a means for coping with the required reduction in the mounting amount of the electronic component 43. Motor holding cylindrical part 13 and disk-shaped wall part 14
And the small-diameter cylindrical portion 15 are integrally formed, and the circuit boards (1) 41,
The circuit board (2) 42 may be mounted on both sides in order to increase the mounting rate of the required electronic components 43, and may be used to stabilize the mounting of the circuit boards (1) 41 and (2) 42. Due to consideration, a disc-shaped wall seat 14a is formed on the disc-shaped wall portion 14 as shown in FIG. 2 to abut and hold the circuit board (1) 41 and the circuit board (2) 42. It is preferable to keep it.

In the present embodiment, the venturi case 10 is formed integrally with a motor holding cylindrical portion 13, a disk-like wall portion 14 at an intermediate portion thereof, and a small-diameter cylindrical portion 15 forming a bearing box. However, it is needless to say that the respective components may be combined with each other.

[0012]

According to the structure of the axial flow fan of the present invention, the mounting area of electronic components can be increased, and the use of a plurality of circuit boards necessary for mounting a large number of required electronic components can be kept to a minimum. As a result, the size of the axial fan can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of an axial fan according to the present invention.

FIG. 2 is a sectional view of a single venturi case of FIG. 1;

FIG. 3 is a front view showing a circuit board on which electronic components according to one embodiment of the axial flow fan according to the present invention are mounted.

FIG. 4 is an effect diagram of the circuit board of FIG. 3;

FIG. 5 is a front view showing a circuit board on which electronic components of a conventional axial fan are mounted.

FIG. 6 is a sectional view of an example of a conventional axial flow fan.

FIG. 7 is a front view of FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Venturi case 11 ... Cylindrical outer wall 12 ... Leg 13 ... Motor holding cylindrical part 14 ... Disk-shaped wall part 14a ... Disk-shaped wall seat 15 ... Small diameter cylindrical part 16 ... Bottom wall part 20 ... Impeller 30 ... Motor 31 ... stator 31a ... stator winding 32 ... stator 40 ... drive circuit 41 ... circuit board (1) 41a ... escape hole 42 ... circuit board (2) 42a ... small-diameter hole 43 ... electronic components

Claims (4)

[Claims] 1. An axial flow fan in which an annular wind tunnel is formed by a cylindrical outer wall and a motor holding cylindrical portion connected to the cylindrical outer wall via a plurality of legs, provided at an intermediate portion of the motor holding cylindrical portion. A disk-shaped wall portion; a small-diameter cylindrical portion integrally formed with the disk-shaped wall portion to form a bearing box; and a drive circuit for driving the electric motor. An axial fan characterized by being disposed axially outside a small-diameter cylindrical portion. 2. An axial flow fan having an annular wind tunnel formed by a cylindrical outer wall and a motor holding cylindrical portion connected to the cylindrical outer wall via a plurality of legs, provided at an intermediate portion of the motor holding cylindrical portion. A disk-shaped wall portion, a small-diameter cylindrical portion integrally formed with the disk-shaped wall portion to form a bearing box, and a drive circuit for driving the electric motor, wherein the drive circuit includes the small-diameter cylindrical portion. A circuit board loosely fitted on the cylindrical surface of at least one of the small-diameter cylindrical portions;
An axial fan having three circuit boards. 3. The axial flow fan according to claim 1, wherein the circuit board disposed outside the small-diameter cylindrical portion in the axial direction has a small hole facing the stator shaft of the electric motor. 4. The axial fan according to claim 1, wherein the disc-shaped wall portion has a plurality of seats for contacting the circuit board on at least one surface.