Laser-welded joint structure between insulation frame and bearing cup of fan and method of forming same

A laser-welded joint structure between insulation frame and bearing cup of fan includes a base having a bearing cup and a stator having at least one insulation frame. The insulation frame includes a sleeve portion defining a bore axially extending therethrough. The sleeve portion is provided on an inner wall surface with at least one pressing section that radially projects into the bore to press a lower side against an upper end of the bearing cup and a bearing received therein. A portion of at least one lateral side of each pressing section that is in contact with the upper end of the bearing cup is melted by laser beam to form a laser-welded joint, so that the insulation frame and the bearing cup are integrally connected together at reduced manufacturing cost and have increased structural strength. A method of forming the laser-welded joint structure is also disclosed.

FIELD OF THE INVENTION

The present invention relates to a joint structure between insulation frame and bearing cup of fan, and more particularly, to a laser-welded joint structure between insulation frame and bearing cup of fan that gives the insulation frame and the bearing cup an increased structural strength at reduce manufacturing cost. The present invention also relates to a method of forming such laser-welded joint structure between an insulation frame and a bearing cup of a fan.

BACKGROUND OF THE INVENTION

There are various kinds of devices, including fans, which are driven by a motor to operate. Therefore, the quality of the motor determines the quality of the device using same. Among others, the bearing is an element that has most important influence on the motor operation. The bearing that fails to lubricate and hold the rotary shaft of the motor in place will produce noise during motor operation or even shortens the motor service life in a worse condition.

To enable sufficient lubricating effect, the bearing for fan is usually an oil-impregnated bearing received in a bearing cup made of a metal material, such as copper. The metal bearing cup is processed by turning and has relatively high precision, so that the oil-impregnated bearing can be easily and properly fitted in the metal bearing cup by way of press fit. Meanwhile, it is also easier to control the tightness of a copper ring that is arranged in the bearing cup by tight fit to locate above the oil-impregnated bearing. The copper ring holds down the bearing in the bearing cup and prevents the bearing from moving out of the bearing cup when it rotates along with the fan's rotary shaft, so that the fan can operate stably.

While the metal bearing cup has the advantage of allowing easy control of the accurate fit between it and the copper ring and the oil-impregnated bearing, it has relatively complex structure and involves complicated processing procedures. When the metal bearing cup has to be additionally turned for forming a stepped inner wall surface for supporting the oil-impregnated bearing thereon, or when the metal bearing cup has an inner diameter too much different from the outer diameter of the oil-impregnated bearing, additional turning is required to expand the inner diameter of the metal bearing cup until an allowable tolerance between the bearing cup inner diameter and the bearing outer diameter is reached. In this case, the overall manufacturing cost of the fan is inevitably increased.

The bearing cup in conventional fans can also be integrally formed of a plastic material by injection molding for use with the oil-impregnated bearing. A copper ring is also provided in the plastic bearing cup above the oil-impregnated bearing for holding down the bearing, so that the bearing is prevented from moving out of the bearing cup when it rotates along with the fan's rotary shaft and the fan can operate stably. While the plastic injection molded bearing cup can be manufactured at lower cost compared to the metal bearing cup, it has its own problem. That is, the bearing cup integrally formed by injection molding tends to have an inner diameter with a relatively large size tolerance, which results in difficulty in well control of the tightness of the copper ring in the bearing cup. When the inner diameter of the injection molded bearing cup is too large, the copper ring is loosely fitted in the bearing cup and fails to effectively hold down the oil-impregnated bearing and prevent the same from moving out of the bearing cup. On the other hand, when the inner diameter of the injection molded bearing cup is too small, different structural damages tend to occur, such as a broken bearing cup and a deformed or shrunk oil-impregnated bearing.

Therefore, the conventional fans, either having a metal bearing cup or a plastic injection molded bearing cup, all have a copper ring for holding down the bearing in the bearing cup to ensure stable fan operation. However, with the trend of designing and manufacturing slim-type electronic products, such as notebook computers, miniature cooling fans having reduced overall thickness are also developed to match the slim-type electronic products.

The conventional miniature fans have a metal or a plastic bearing cup that can receive an oil-impregnated bearing therein but not the copper ring. This is because the currently available technique fails to manufacture a copper ring that can match the size of the bearing cup of the miniature fan. Therefore, the existing miniature fans do not have a copper ring mounted in the bearing cup thereof. As a result, when the miniature fans operate, the oil-impregnated bearing thereof tends to slide in the bearing cup to produce noise, shorten the fan service life, and adversely affect the fan rotational efficiency.

It is therefore tried by the inventor to develop a laser-welded joint structure between insulation frame and bearing cup of fan to solve the problems and disadvantages in prior art fan structures.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a laser-welded joint structure between insulation frame and bearing cup of fan to reduce the fan manufacturing cost.

Another object of the present invention is to provide a laser-welded joint structure between insulation frame and bearing cup of fan that gives the insulation frame and the bearing cup an increased structural strength.

A further object of the present invention is to provide a fan that employs a laser-welded joint structure between an insulation frame and a bearing cup thereof, so as to hold a bearing in place in the bearing cup and achieve stable fan operation; and the fan can be a general axial flow fan or a miniature centrifugal or axial flow fan.

A still further object of the present invention is to provide a method of forming a laser-welded joint structure between an insulation frame and a bearing cup of a fan to reduce the fan manufacturing cost.

A still further object of the present invention is to provide a method of forming a laser-welded joint structure between an insulation frame and a bearing cup of a fan, so as to give the insulation frame and the bearing cup an increased structural strength.

A still further object of the present invention is to provide a method of forming a laser-welded joint structure between an insulation frame and a bearing cup for general axial flow fan or miniature centrifugal or axial flow fan, so as to hold a bearing in place in the bearing cup and achieve stable fan operation.

To achieve the above and other objects, the laser-welded joint structure between insulation frame and bearing cup of fan according to the present invention includes a base and a stator. The base has a bearing cup forward projected therefrom to internally define a bearing receiving hole for accommodating a bearing therein. The stator includes at least one insulation frame, which has a sleeve portion fitted around the bearing cup and a bore axially extending through the sleeve portion and communicating with the bearing receiving hole. The sleeve portion is provided on an inner wall surface with one or more pressing sections that radially inward project into the bore with a lower side thereof pressing against the bearing and an upper end of the bearing cup. A portion of at least one lateral side of each pressing section that is in contact with the upper end of the bearing cup is melted by laser beam, for example, to form a welded joint, via which the pressing section is connected to the upper end of the bearing cup. With the laser-welded joint structure between insulation frame and bearing cup of fan according to the present invention, it is able to effectively increase the structural strength of the insulation frame and the bearing cup and reduce the fan manufacturing cost.

To achieve the above and other objects, the method of forming laser-welded joint structure between insulation frame and bearing cup of fan according to the present invention includes the steps of (a) providing a base and a stator; the base having a bearing cup internally defining a bearing receiving hole for accommodating a bearing therein; the stator including at least one insulation frame, which has a sleeve portion and a bore axially extending through the sleeve portion and communicating with the bearing receiving hole; and the sleeve portion being provided on an inner wall surface with at least one pressing section that radially inward projects into the bore; (b) fitting the sleeve portion around the bearing cup to press a lower side of each pressing section against the bearing and an upper end of the bearing cup; and (c) projecting a laser beam to melt a portion of one lateral side of each pressing section that is in contact with the upper end of the bearing cup, so as to form a welded joint that integrally connects the insulation frame to the bearing cup. With the method of forming laser-welded joint structure between insulation frame and bearing cup of fan according to the present invention, it is able to effectively increase the structural strength of the insulation frame and the bearing cup and reduce the fan manufacturing cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.

Please refer toFIGS. 1 and 2Athat are exploded and assembled perspective views, respectively, of a laser-welded joint structure between insulation frame and bearing cup of fan according to a first preferred embodiment of the present invention; and toFIG. 2Bthat is a vertical sectional view ofFIG. 2A. As shown, the first preferred embodiment of the present invention includes a base10and a stator13. The base10has a bearing cup101axially forward extended from a center of the base10. The bearing cup101internally defines an axially extended bearing receiving hole1011for accommodating a bearing12therein. In the illustrated first preferred embodiment, the bearing12is shown as an oil-impregnated bearing. However, in practical implementation of the present invention, the bearing12is not necessarily limited to the oil-impregnated bearing, but can be a ball bearing, a hydro bearing or other types of bearings.

The stator13includes at least one insulation frame131, a silicon steel plate assembly137, and a plurality of coils138. The insulation frame131includes an upper insulation frame1311, a lower insulation frame1312, a sleeve portion133, and a bore134. The upper and the lower insulation frame1311,1312are assembled to an upper and a lower side of the silicon steel plate assembly137, respectively; and the coils138are wound on the upper and the lower insulation frame1311,1312. The sleeve portion133includes a first sleeve1331and a second sleeve1332, which are centered in the upper and the lower insulation frame1311,1312, respectively, to together enclose the bearing cup101therein. In brief, the sleeve portion133is fitted on around the bearing cup101.

In the illustrated first preferred embodiment, the insulation frame131and the bearing cup101are made of the same material. That is, the insulation frame131and the bearing cup101can be similarly made of a plastic material or a metal material. However, in practical implementation of the present invention, the insulation frame131and the bearing cup101may be otherwise made of different materials. For example, the insulation frame131may be made of a plastic material while the bearing cup101is made of a metal material; or alternatively, the insulation frame131may be made of a metal material while the bearing cup101is made of a plastic material.

The bore134axially extends from the first sleeve1331to the second sleeve1332of the sleeve portion133, and an open end of the bore134at the first sleeve1331of the sleeve portion133is communicable with the bearing receiving hole1011in the bearing cup101. The upper sleeve1331is provided on an inner wall surface with at least one pressing section135that radially inward projects into the bore134. The pressing section135has a lower side pressed against an upper end of the bearing cup101and the bearing12fitted in the bearing cup101to provide a holding-down force on the bearing12and accordingly, effectively hold the bearing12in place in the bearing cup101. In the illustrated first preferred embodiment, there are shown four pressing sections135equally spaced along the inner wall surface of the upper sleeve1331to extend into the bore134.

However, in practical implementation of the present invention, the number of the pressing sections135is not necessarily limited to four but can be increased or decreased according to required structural strength and holding-down force in design. Further, the pressing sections135can be otherwise non-equally spaced along the inner wall surface of the upper sleeve1331.

As can be seen inFIGS. 1,2A and2B, the pressing sections135radially inward extended from the inner wall surface of the upper sleeve1331respectively have a free end1351extended into a central area of the bore134to press against the bearing12. Further, a separating space136is defined between any two adjacent pressing sections135, and the separating spaces136are communicable with the bore134.

A portion of one lateral side of each pressing section135that is in contact with the upper end of the bearing cup101is welded to the upper end of the bearing cup101by way of laser processing, such as laser welding, to form a welded joint151thereat. That is, the welded joint151connects one lateral side of the pressing section135to the upper end of the bearing cup101, so that the pressing section135on the insulation frame131and the upper end of the bearing cup101are welded together to form an integral body. In this manner, both the insulation frame131and the bearing cup101can have effectively enhanced structural strength while the bearing12can be stably held in the bearing cup101.

In practical implementation of the present invention, the portions on both lateral sides of each pressing section135that are in contact with the upper end of the bearing cup101can be laser-welded to the upper end of the bearing cup101at the same time to form two welded joints151thereat.

By forming the welded joints151at the contact areas between the pressing sections135of the insulation frame131and the upper end of the bearing cup101, both of the insulation frame131and the bearing cup101can have effectively enhanced structural strength, and the stator13and the base10can be assembled together at reduced manufacturing cost.

FIGS. 4A and 4Bare assembled and exploded perspective views, respectively, of a fan1according to a second preferred embodiment of the present invention. Please refer toFIGS. 4A and 4Balong withFIG. 2A. The fan1adopts the laser-welded joint structure between insulation frame and bearing cup according to the first preferred embodiment of the present invention. While the fan1in the illustrated second preferred embodiment is a miniature centrifugal fan, it is understood the fan1is not necessarily limited thereto but can be, for example, an axial flow fan as that shown inFIGS. 5A and 5Bfor use with other electronic products, such as a notebook computer, a desktop computer, and other industrial or home electronic devices.

The fan1includes a frame16, a rotor17, and a stator13as that in the first preferred embodiment of the present invention. The frame16has an air inlet161, an air outlet162communicable with the air inlet161, and a receiving space164defined in the frame16between the air inlet161and the air outlet162. A base10is provided in the frame16to locate near a central area of the receiving space164, and the rotor17is rotatably connected to a bearing cup101forward projected from the base10. The stator13is assembled to the bearing cup101in the same manner as that described in the first preferred embodiment of the present invention. When the fan1operates, the free ends1351of the pressing sections135are pressed against a bearing12mounted in the bearing cup101to hold the bearing12in place. Meanwhile, with the welded joints151formed between the pressing sections135of the insulation frame131of the stator13and the upper end of the bearing cup101, the insulation frame131and the bearing cup101both have largely increased structural strength.

FIG. 6is a flowchart showing four steps S1to S4included in a method according to a third preferred embodiment of the present invention for forming the laser-welded joint structure between insulation frame and bearing cup of fan as described in the first preferred embodiment of the present invention; andFIGS. 7A and 7Bare pictorial illustrations of the method according to the third preferred embodiment of the present invention. Please refer toFIGS. 6,7A and7B along withFIGS. 1 and 2A.

In the step S1, a base and a stator are provided. The base has a bearing cup, which internally defines a bearing receiving hole for accommodating a bearing therein; and the stator includes at least one insulation frame, which has a sleeve portion and a bore axially extending through the sleeve portion. The bore is communicable with the bearing receiving hole, and the sleeve portion is provided on an inner wall surface with at least one pressing section that radially inward projects into the bore.

More specifically, a base10and a stator13are provided. The base10has a bearing cup101that is forward extended from the base10and internally defines a bearing receiving hole1011for accommodating a bearing12therein. The stator13includes at least one insulation frame131, which has a sleeve portion133and a bore134axially extending through the sleeve portion133(i.e. the above-mentioned first and the second sleeve1331,1332). The bore134is communicable with the bearing receiving hole1011, and the first sleeve1331is provided on an inner wall surface with one or more pressing sections135that radially inward project into and are circumferentially equally or non-equally spaced in the bore134. Wherein, the insulation frame131and the bearing cup101can be made of different materials or the same material.

In the step S2, fit the sleeve portion around the bearing cup to press a lower side of the pressing sections against the bearing and an upper end of the bearing cup.

More specifically, the sleeve portion133is fitted around the bearing cup101with a lower side of the pressing sections135pressed against the bearing12and an upper end of the bearing cup101, as shown inFIG. 2A, so as to provide a holding-down force on the bearing12and accordingly, effectively hold the bearing12in place in the bearing cup101.

In the step S3, project a laser beam to melt a portion of one lateral side of each pressing section that is in contact with the upper end of the bearing cup, so as to form a welded joint that integrally connects the insulation frame to the bearing cup.

More specifically, as shown inFIG. 7A, use a laser device2to project a laser beam21on a portion of one lateral side of each pressing section135that is in contact with the upper end of the bearing cup101, so that the laser irradiated portions are molten and then set to form a plurality of welded joints151, via which the insulation frame131is connected to the bearing cup101to form an integral body.

In the step S4, project a laser beam to melt a portion of another lateral side of each pressing section that is in contact with the upper end of the bearing cup, so that the pressing sections are laser-welded at two lateral sides to the upper end of the bearing cup.

More specifically, as shown inFIG. 7B, use the laser device2to project the laser beam21on a portion of another lateral side of each pressing section135that is in contact with the upper end of the bearing cup101, so that the laser irradiated portions are molten and then set to further form a plurality of welded joints151. The welded joints151between two lateral sides of the pressing sections135and the upper end of the bearing cup101largely increase the structural strength of the insulation frame131and the bearing cup101.

With the method according to the third preferred embodiment of the present invention, the insulation frame of the stator and the bearing cup of a fan can be joined to obtain increased structural strength at effectively reduced cost; and the insulation frame and the bearing cup connected via the laser-welded joint structure can be more advantageously applied to general fans, such as axial flow fans, or to miniature fans, including centrifugal fans and axial flow fans, for use in different electronic products.

In conclusion, the present invention has the following advantages: (1) saving fan manufacturing cost; (2) utilizing the welded joints between the lateral sides of the pressing sections of the insulation frame and the upper end of the bearing cup to integrally connect the insulation frame to the bearing cup, effectively hold the bearing in place, and give the insulation frame and the bearing cup an increased structural strength; and (3) being applicable to general axial flow fans or miniature fans used with various electronic products, such as desktop and notebook computers.