TW201915343A - Axial fan - Google Patents

Abstract

An axial fan comprises: a shaft, which is a rotating shaft; an air dynamic pressure bearing that through air dynamic pressure minimizes radial shifting of the shaft; a metal frame having a circular surface in the middle of which is provided a first hole through which the shaft passes, and having a cylindrical shape closed at one end; and a resinous impeller which covers the frame such that the frame is accommodated in the interior, and which is centered between the shaft and the inner side of a second hole provided to the center of the circular surface.

Description

Axial fan

The invention relates to an axial flow fan.

A wide variety of axial fans are widely known. For example, in the outer rotor type air blowing fan, an adjustment member that changes the natural frequency of the machine mounting portion is provided to suppress resonance (see Patent Document 1).

However, in the case where the axial flow fan has a shape in which a resin impeller covers a cylindrical metal rotor seat, the impeller may be cracked. This is due to the fact that once the axial fan is operated, the rotor seat will generate heat and the coefficient of linear expansion of the metal and resin will be different. In particular, in the case of such a fan, since the contact portion between the side surface forming the outer circumference of the rotor seat and the impeller is centered, it is impossible to make the contact portion have an excessive gap, and such a crack is likely to occur. Prior technical literature

Patent Document Patent Document 1: Japanese Patent No. 6138995

SUMMARY OF THE INVENTION An object of an embodiment of the present invention is to provide an axial flow fan which has improved durability in consideration of thermal expansion.

An axial flow fan according to the aspect of the present invention includes: a shaft member that is a rotating shaft; and a gas dynamic pressure bearing that suppresses radial fluctuation of the shaft member by gas dynamic pressure; the frame body is made of metal and has a cylindrical shape One end has a shape blocked by a circular surface, the circular surface is provided with a first hole through which the shaft member can pass, and an impeller is made of resin, and covers the frame body to house the frame body therein. The centering is completed between the inner side of the second hole provided at the center of the circular surface and the shaft member.

Form for carrying out the invention (embodiment)

Fig. 1 is a perspective view showing a configuration of an axial fan 10 according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing the configuration of the axial flow fan 10 of the embodiment.

The axial fan 10 can be used as, for example, a cooling fan for cooling the servo. The axial fan 10 includes a motor body 1, an impeller 2, and an outer base 3.

Fig. 3 is a perspective view showing the configuration of the motor main body 1 of the embodiment.

The motor body 1 is divided into a rotating body that rotates and a stationary portion that is stationary with respect to the rotation of the rotating body.

The rotating body of the motor body 1 is composed of a shaft member 11, a shaft seat 12, a frame body 13, and a magnet 14. The shaft seat 12 and the frame body 13 form a rotor seat.

The stationary portion of the motor body 1 is composed of a substrate 15, a plurality of coils 16, a core member 17, and a plurality of support members 18.

The shaft member 11 is a rotating shaft of the rotating body and has a cylindrical shape. The shaft member 11 is made of metal such as iron.

The shaft base 12 has an annular shape, a flat surface, and a rear surface that is fitted into the hole of the frame body 13. The shaft base 12 is joined in a state in which the upper portion of the shaft member 11 is fitted into a hole in the center of the surface. The bottom surface portion of the axle seat 12 is engaged with the upper portion of the frame body 13. The material of the shaft seat 12 is an object that selects a line expansion coefficient close to the metal of the material of the frame body 13, thereby suppressing the offset of the shaft seat 12 from the frame body 13 due to thermal expansion. Specifically, when the frame body 13 is made of iron, the shaft base 12 is preferably made of brass or steel. Brass is less prone to rust than steel and is therefore suitable for the material of the shaft seat 12.

The frame body 13 has a shape in which a circular surface (upper surface) which is closed at one end of the cylindrical shape is provided with a hole in the center where the shaft member 11 can protrude. The hole on the upper surface of the frame body 13 is in a state in which the shaft member 11 is penetrated, and the gap formed between the shaft member 11 and the frame body 13 can be covered by the shaft seat 12. The frame body 13 is made of metal such as iron. The frame body 13 is formed by press working.

The magnet 14 is a permanent magnet for providing a function as a rotor of the motor body 1. The magnet 14 has a cylindrical shape and is attached to the inner side of the frame body 13.

The substrate 15 has a circular plate shape and is provided at the center with a hole through which the shaft member 11 is inserted. The substrate 15 has a control circuit mounted to drive the motor body 1. A sensor 151 is provided on the substrate 15 to detect the rotational position of the rotor. Further, the substrate 15 can also be used for a sensorless motor in which the sensor 151 is not provided. Further, the substrate 15 may be mounted on the outer casing 3 without being mounted on the motor body 1. Such a configuration is used, for example, on a sensorless motor that is not provided with the sensor 151.

The coil 16 and the core member 17 are provided inside the frame body 13. Each of the coils 16 is wound around the core member 17, and is disposed around the shaft member 11 at equal intervals on the circumference. The coil 16 and the core member 17 have a function as a stator of the motor body 1. Further, the core member 17 may also be composed of a plurality of members. For example, the core member 17 may be a structure in which a thin plate is stacked in the direction of the rotation axis to suppress eddy current loss.

The plurality of support members 18 include a member that supports the rotating body to be rotatable relative to the stationary portion of the motor body 1, and a member that supports the stationary portion of the motor body 1 to be fixed to the outer base 3. For example, the support member 18 is a member for arranging the coil 16 and the core 17, or a rod-shaped member that is inserted through the small hole of the substrate 15 to fix the stationary portion to the outer casing 3.

Fig. 4 is a perspective view showing a configuration of the impeller 2 of the embodiment as seen from the lower side. FIG. 5 is a perspective view showing a state in which the impeller 2 of the embodiment is mounted on the motor main body 1.

The impeller 2 is made of a resin such as plastic. The impeller 2 has a shape in which a plurality of blades 22 are provided on the impeller body 21, and the impeller body 21 has a shape in which one end of the cylindrical shape is blocked. Further, the impeller body 21 has a shape in which a hole for fitting the outer peripheral surface of the shaft base 12 is provided at the center on the circular surface (upper surface). In order to prevent cracks caused by thermal expansion, the periphery of the hole of the upper surface of the impeller body 21 has a sufficient thickness. The shape of the inner side of the impeller body 21 is a shape in which the frame body 13 can be fitted from the upper portion. A concave portion coated with an adhesive may be disposed on the inner side of the impeller body 21, and the adhesive is used to adhere to the frame body 13. The blade 22 is shaped to allow wind to flow in the direction of the rotation axis when it is shaped to rotate. The impeller 2 is configured to cover the frame body 13 and is provided with a hole into which the outer shape of the shaft seat 12 can be fitted to the upper surface. By fitting the outer shape of the shaft base 12 into the hole on the upper surface of the impeller 2, the motor body 1 is in a centering state. The inner circumferential surface of the impeller body 21 and the outer circumferential surface of the frame body 13 are adhered by an adhesive.

Fig. 6 is a perspective view showing a configuration in which the outer casing 3 of the embodiment is vertically cut.

The outer casing 3 is provided with a cup portion 31, a plurality of stationary blades (ribs) 32, an outer shape portion 33, a bearing sleeve 34, and a magnetic bearing 35.

The cup portion 31 is disposed at the center of the bottom surface portion of the outer housing 3. The cup portion 31 is where the motor body 1 is mounted. The motor body 1 is disposed on the bottom surface of the cup portion 31 such that the impeller 2 is positioned above. The substrate 15 is configured to be fixed inside the cup portion 31. The outer shape of the cup portion 31 is larger than the outer shape of the substrate 15. Therefore, in a state where the motor body 1 is mounted, there is a slight gap between the outer edge of the outer periphery of the cup portion 31 and extending in the vertical direction and the substrate 15. Further, when the substrate 15 is mounted on the outer casing 3, the substrate 15 is disposed to adhere to the outer edge of the cup portion 31, and at the position where the central hole is penetrated by the shaft member 11, the inner circumference of the hole A little gap is created.

The stationary blades 32 are disposed at equal intervals around the cup portion 31 to connect the outer peripheral surface of the cup portion 31 and the inner peripheral surface of the outer shape portion 33. The stationary blade 32 is shaped to pass the wind between the adjacent two stationary blades 32 in the direction of the rotation axis as the rotating body rotates. In order to ensure the flow characteristics of the air, the stationary blade 32 is formed into a thin shape using a flexible material such as a resin.

The outer shape portion 33 is a portion covering the outermost side of the axial flow fan 10. The outer shape portion 33 has a shape in which a quadrangular flange portion is provided at both ends of the cylindrical portion of the motor main body 1, and the flange portion is provided with a hole for mounting the axial flow fan 10 at the mounting portion.

A bearing sleeve 34 is provided at the center of the cup portion 31. The bearing sleeve 34 has a cylindrical shape. The motor body 1 is mounted such that the shaft member 11 is inserted into the bearing sleeve 34. The bearing sleeve 34 is a gas dynamic pressure bearing for suppressing the radial variation of the shaft member 11. When the shaft member 11 is rotated, the gap between the shaft member 11 and the bearing sleeve 34 is kept constant due to the dynamic pressure of the gas around the shaft member 11, whereby the fluctuation of the shaft member 11 is suppressed. Therefore, when the shaft member 11 is rotated, the shaft member 11 and the bearing sleeve 34 remain untouched.

The magnetic bearing 35 is provided at a portion located at the bottom surface of the bearing sleeve 34. The magnetic bearing 35 is mainly composed of a permanent magnet. The magnetic bearing 35 suppresses the thrust direction of the shaft member 11 by the attraction force or repulsive force generated by the magnetic properties of the permanent magnets. Therefore, the shaft member 11 and the magnetic bearing 35 remain untouched. Further, if it is a bearing capable of suppressing the fluctuation of the shaft member 11 in the thrust direction, it is not limited to the magnetic bearing 35, and may be any type of bearing. As with the magnetic bearing 35, as long as it is a non-contact type bearing that keeps the shaft member 11 untouched, it is excellent in durability and suitable for high-speed rotation, but may be a contact type bearing.

Next, the centering of the axial fan 10 will be described.

As shown in FIGS. 1 and 2, the portion where the outer peripheral surface of the upper portion of the boss 12 contacts the inner side of the hole of the upper surface of the impeller 2 is the centering portion SN of the axial fan 10. When the axial fan 10 is manufactured, centering adjustment is performed at the centering point SN so that the center of the rotating shaft of the shaft member 11 becomes a desired position.

Since the axial fan 10 is manufactured at a normal temperature, it is necessary to consider the heat generated by the operation of the axial fan 10 to cause the components to thermally expand. The effect of this thermal expansion is that the centering point SN is relatively small, and the centering point SN is located inside the hole having a diameter smaller than the inner peripheral surface of the impeller 2. For example, in consideration of thermal expansion, if a gap of 50 to 150 μm is required between the inner circumferential surface of the impeller 2 and the outer circumferential surface of the frame body 13, the centering portion SN is the inner circumferential surface of the shaft seat 12 and the inner side of the hole of the upper surface of the impeller 2. The gap is only required to be 0 to 50 μm.

Since the centering adjustment is performed at the centering portion SN, it is not necessary to perform centering at the contact between the inner circumferential surface of the impeller 2 and the outer circumferential surface of the frame body 13, so that the difference in linear expansion coefficient between the impeller 2 and the frame body 13 can be considered. , fully widen the gap at the contact to avoid cracks. Further, by providing the centering portion SN on the inner side of the hole having a diameter smaller than the inner peripheral surface of the impeller 2, it is necessary to ensure a narrow gap width in consideration of thermal expansion, so that the centering accuracy can be improved. .

Next, an example of a method of correcting the mass imbalance of the rotating body of the axial fan 10 will be described.

The shaft seat 12 is disposed around the upper portion of the shaft member 11. The material of the shaft seat 12 is brass which is relatively heavy in weight and easy to be machined. Therefore, the mass balance correction by the minus balance method is performed by cutting the shaft base 12. Here, a method of correcting the mass imbalance by drilling a circular hole in a drilling machine will be described as an example, but what is to be used and how to perform the cutting process.

First, the mass balance of the rotating body of the axial flow fan 10 is measured. Based on this measurement, it is determined where the drilling machine is drilled in the shaft seat 12 and the depth. According to the result of this decision, the drill is drilled in the shaft seat 12. The location and depth of the hole can be determined mechanically by using a conventionally known method. Therefore, it is also possible to automate the work of correcting the machining from the measurement of the mass balance to the determination of the position and depth of the hole and the mass imbalance of the shaft seat 12.

Further, the method of correcting the mass imbalance is not limited to the above method, and may be performed in any manner. For example, a mass balance correction in the plus balance mode can also be performed. As a specific example, a groove is provided around the upper portion of the shaft member 11, and an adhesive having a relatively large specific gravity is applied to the groove to perform mass imbalance correction.

According to the present embodiment, since the center hole is centered at the centering portion SN where the outer peripheral surface of the shaft seat 12 to which the shaft member 11 is fitted and the inner surface of the upper surface of the impeller 2 is centered, it is not necessary to be in the impeller. Centering is performed between the inner circumferential surface of the second surface and the outer circumferential surface of the frame body 13. Therefore, it is possible to ensure that the gap between the inner circumferential surface of the impeller 2 and the outer circumferential surface of the frame body 13 is wide in consideration of thermal expansion. Therefore, it is possible to prevent the impeller 2 from being cracked due to the difference in the linear expansion coefficient of the material of the impeller 2, that is, the resin and the material of the frame 13, that is, the metal.

Further, since the diameter of the centering portion SN of the impeller 2 is smaller than the diameter of the inner peripheral surface of the impeller 2, the magnitude of the change due to thermal expansion also becomes small. Therefore, by centering at the centering point SN, the width of the gap in consideration of thermal expansion can be made smaller than the case where centering is performed on the inner circumferential surface of the impeller 2, so that the accuracy of the centering can be improved.

Further, by using the non-contact type gas dynamic pressure bearing as the bearing of the shaft member 11, the high-durability axial flow fan 10 suitable for high-speed rotation can be formed as compared with the contact type ball bearing. Further, by using a non-contact type magnetic bearing as the thrust bearing, it is possible to manufacture the axial flow fan 10 which is more suitable for high-speed rotation and excellent in durability.

Further, by providing the machinable shaft base 12, the mass imbalance correction of the rotating body can be easily performed in a negative balance manner.

Further, as a modification of the embodiment, the following configuration may be employed. The shaft seat 12 is not provided, and the burring is performed so that the hole on the upper surface of the frame body 13 is sized to fit the shaft member 11, and the circumference of the hole is vertically erected. The hole of the upper surface of the impeller 2 is reduced so as to be fitted to the outer peripheral surface of the hole of the frame body 13 through the punching. In this configuration, the contact between the inner side of the hole of the upper surface of the impeller 2 and the outer peripheral surface of the hole of the frame body 13 by the punching edge is regarded as the centering point SN. Therefore, as in the present embodiment, it is possible to ensure that the gap between the inner circumferential surface of the impeller 2 and the outer circumferential surface of the frame body 13 is wide in consideration of thermal expansion. Therefore, it is possible to suppress the occurrence of cracks due to the difference in the linear expansion coefficients of the two materials, thereby improving the durability. Moreover, compared with the case where centering is performed on the inner peripheral surface of the impeller 2, since centering can be performed in the smaller diameter, the precision of centering can be improved.

Further, the present invention is not limited to the above-described embodiments, and any constituent elements may be deleted, added, changed, or the like. Further, in a plurality of embodiments, constituent elements may be combined or exchanged to create a new embodiment. Even if the embodiment is different from the above-described embodiment, the same as the gist of the present invention will be described as an embodiment of the present invention, and the description thereof will be omitted.

1‧‧ ‧ motor body

10‧‧‧Axial fan

11‧‧‧ shaft parts

12‧‧‧ shaft seat

13‧‧‧ ‧ frame

14‧‧‧ magnet

15‧‧‧Substrate

151‧‧‧ sensor

16‧‧‧ coil

17‧‧‧ core pieces

18‧‧‧Support members

2‧‧‧ Impeller

21‧‧‧The impeller body

22‧‧‧ blades

3‧‧‧Outer stand

31‧‧‧ Cup parts

32‧‧‧ stationary wing

33‧‧‧ Shape part

34‧‧‧ bearing sleeve

35‧‧‧Magnetic bearing

SN‧‧‧ Center

Fig. 1 is a perspective view showing a configuration of an axial flow fan according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing the configuration of an axial flow fan of the embodiment.

Fig. 3 is a perspective view showing a configuration of a motor main body of the embodiment.

Fig. 4 is a perspective view showing a configuration of the impeller according to the embodiment as seen from the lower side.

Fig. 5 is a perspective view showing a state in which an impeller according to the embodiment is mounted on a motor body.

Fig. 6 is a perspective view showing a configuration in which an outer casing of the embodiment is vertically cut.

Claims (7)

An axial flow fan comprising: a shaft member and a rotating shaft; and a gas dynamic pressure bearing for suppressing radial variation of the shaft member by gas dynamic pressure; the frame body is made of metal and has a cylindrical shape One end has a shape blocked by a circular surface, the circular surface is provided with a first hole through which the shaft member can pass, and an impeller is made of resin, and covers the frame body to house the frame body therein. The centering is completed between the inner side of the second hole provided at the center of the circular surface and the shaft member. The axial flow fan of claim 1, wherein a gap between an outer circumferential surface of the frame body and an inner circumferential surface of the impeller is wider than a gap that is centered between the inner side of the second hole of the impeller and the shaft member. The axial flow fan of claim 1, comprising: a shaft seat that is annular, and that is engaged in a state in which the shaft member is fitted in the third hole, and is provided to block the first hole of the frame body; The centering is completed between the outer peripheral surface and the inner side of the second hole of the impeller. The axial flow fan of claim 3, wherein the aforementioned shaft seat is made of brass. The axial flow fan according to any one of claims 1 to 4, further comprising: a magnetic bearing that suppresses a thrust direction fluctuation of the shaft member by magnetism. The axial flow fan of claim 3 or 4, wherein the shaft seat is provided to correct the mass imbalance of the rotating body by being cut. A method for manufacturing an axial flow fan, comprising: providing a gas dynamic pressure bearing, wherein the gas dynamic pressure bearing suppresses a radial fluctuation of a rotating shaft, that is, a shaft member by a gas dynamic pressure; and covering the resin impeller The metal frame body has a shape in which the frame body is housed inside, and the frame body has a cylindrical shape and is closed by a circular surface. The circular surface is provided with a first hole through which the shaft member can pass. And centering between the inner side of the second hole provided at the center of the circular surface of the impeller and the shaft member.