Cooling fan with circuit board positioning structure and an assembly method thereof

A cooling fan includes a fan frame, a circuit board, a stator-coil unit and an impeller. The fan frame includes a metal seat and a lateral wall. The metal seat includes an engaging face and an engaging portion arranged on the engaging face. The lateral wall is arranged on a periphery of the metal seat and includes an air inlet and an air outlet. The circuit board includes a positioning hole. The circuit board is press fit around the engaging portion of the metal seat via the positioning hole and adhered to the engaging face of the metal seat. The circuit board includes an insulation layer facing the metal seat. The stator-coil unit is mounted on the metal seat of the fan frame and electrically connected to the circuit board. The impeller is rotatably coupled with the stator-coil unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a cooling fan and an assembly method thereof and, more particularly, to a cooling fan having a metal seat and a circuit board easily mounted on the metal seat while insulation between the circuit board and the metal seat is ensured, as well as to an assembly method of the cooling fan.

2. Description of the Related Art

FIG. 1shows an engagement structure of a stator unit of a cooling fan disclosed in Taiwan Patent No. M387164. The cooling fan8includes a housing81, a stator unit82and a blade unit83. The housing81forms a seat811and a shaft tube812by integral injection. The seat811has a plurality of first engaging portions813. The stator unit82has a stator821consisting of a plurality of stacked coils and silicon steel plates. The stator821is coupled with a circuit board822and includes a plurality of second engaging portions823.

In assembly, the circuit board822is coupled to the bottom face of the stator821by forcing the second engaging portions823of the stator821through the holes of the circuit board822. The stator821is then mounted on the seat811by forcing the shaft tube812through the circuit board822and the stator821. Next, the first engaging portions813and the second engaging portions823are engaged with each other. Finally, the blade unit83is coupled with the shaft tube812to complete the assembly procedure of the cooling fan8.

However, the height of the cooling fan8cannot be reduced due to the arrangements of the first engaging portions813and the second engaging portions823. As a result, it is difficult to miniaturize the cooling fan8. Furthermore, it is inconvenient to assemble the cooling fan8due to the steps of coupling the circuit board822with the stator unit82and engaging the second engaging portions823with the first engaging portions813. Moreover, the first engaging portions813or the second engaging portions823could break during the assembly procedure, affecting the engagement between the seat811and the stator unit82. Still further, since the housing81is made of plastic, certain parts of the seat811(such as ribs) are fragile. Consequently, the structural strength of the cooling fan8is low, and the quality of the cooling fan8is poor.

To solve the problem, Taiwan Patent No. 1353509 discloses a fan casing structure as shown inFIG. 2. The fan casing9includes a support board91. The support board91includes a bottom plate911and a shaft tube portion912located at the center of the bottom plate911. The support board91may be mounted with certain components, such as a stator unit, a blade unit or the like, to construct a cooling fan.

Although the bottom plate911of the fan casing9has higher strength and quality, it is still inconvenient to assemble a cooling fan using the fan casing9and is still difficult to reduce the height of the cooling fan, as it is the case of the cooling fan8. This is because it is inconvenient to form the stator unit by assembling the silicon steel plates, the coils and the circuit board before the stator unit can be installed in the fan casing9(the coils and the circuit board are essential components to the stator unit, as can be readily appreciated by one skilled in the art). More importantly, it is also difficult to ensure satisfactory insulation between the circuit board and the bottom plate911, since the bottom plate911is made of metal.

SUMMARY OF THE INVENTION

It is therefore the objective of this invention to provide a method of assembly directed to assembly of a cooling fan. The method of assembly allows the stator-coil unit to be installed after assembly of the circuit board, simplifying the assembly procedure of the cooling fan.

It is another objective of this invention to provide a method of assembly directed to assembly of a cooling fan. The method of assembly allows easy arrangement of the enameled copper wire of the circuit board as well as easy positioning of the circuit board.

It is yet another objective of this invention to provide a cooling fan with satisfactory insulation between the metal seat and the circuit board when the circuit board is adhered to the metal seat.

It is yet another objective of this invention to provide a cooling fan with a reduced height by adhesion of the circuit board to the metal seat.

It is yet another objective of this invention to provide a cooling fan with convenient assembly by arrangement of an insulation layer between the circuit board and the metal seat. The insulation layer is in the form of a film with adhesion and insulation functions.

A cooling fan including a fan frame, a circuit board, a stator-coil unit and an impeller is disclosed in an embodiment of the invention. The fan frame includes a metal seat and a lateral wall. The metal seat comprises an engaging face and an engaging portion arranged on the engaging face. The lateral wall is arranged on a periphery of the metal seat and defines an air inlet and an air outlet. The circuit board includes a positioning hole. The circuit board is press fit around the engaging portion of the metal seat via the positioning hole and adhered to the engaging face of the metal seat. The circuit board includes an insulation layer facing the metal seat. The stator-coil unit is mounted on the metal seat of the fan frame and electrically connected to the circuit board. The impeller is rotatably coupled with the stator-coil unit.

In a preferred form shown, the engaging portion has one end protruding from the engaging face of the metal seat. The end of the engaging portion is adapted to be coupled with the stator-coil unit.

In the preferred form shown, the end of the engaging portion extends through the positioning hole of the circuit board. The end of the engaging portion protrudes from the circuit board.

In the preferred form shown, the stator-coil unit forms a positioning groove. The end of the engaging portion extends into the positioning groove.

In the preferred form shown, the stator-coil unit comprises a shaft-coupling member, a silicon steel plate unit and a coil unit. The shaft-coupling member has one end being a fixed end. The fixed end is coupled with the engaging portion of the metal seat. The silicon steel plate unit is fit around the shaft-coupling member. The coil unit is formed by an enameled copper wire wound around a predetermined portion of the silicon steel plate unit.

In the preferred form shown, the positioning groove is formed between the fixed end of the shaft-coupling member and the silicon steel plate unit.

In the preferred form shown, the circuit board comprises at least one electrical contact. The coil unit comprises at least one electrical connection end electrically connected to the at least one electrical contact.

In the preferred form shown, the metal seat comprises a wire-positioning hole on the engaging face. A wire channel extends from the periphery of the metal seat to an edge of the wire-positioning hole. The circuit board comprises a lead wire. The lead wire has a first end electrically coupled to the circuit board. The lead wire has a second end passing through the wire-positioning hole and extending along the wire channel for connection to an external power source or a driving circuit.

In the preferred form shown, the circuit board further comprises an electrical connection port aligned with the wire channel.

In the preferred form shown, the lateral wall is a plastic material formed on the periphery of the metal seat by integral injection molding.

In the preferred form shown, the cooling fan further comprises a cover coupled with the lateral wall. The cover has a hole corresponding to the air inlet.

In the preferred form shown, the metal seat further comprises a plurality of vents.

Furthermore, an assembly method of a cooling fan is disclosed. The assembly method comprises providing a fan frame having a metal seat, providing a circuit board having a positioning hole and an insulation layer, and mounting the circuit board on the metal seat by fitting the circuit board around an engaging portion of the metal seat via the positioning hole. The insulation layer faces the metal seat. The assembly method further comprises mounting a stator-coil unit on the metal seat and electrically connecting the stator-coil unit to the circuit board. The assembly method further comprises rotatably coupling an impeller with the stator-coil unit.

In a preferred form shown, the assembly method further comprises providing a shaft-coupling member. A silicon steel plate unit that is wound with a coil unit is coupled with an outer circumferential face of the shaft-coupling member.

In the preferred form shown, the assembly method further comprises pulling an electrical connection end of the coil unit from the coil unit before the stator-coil unit is mounted on the metal seat, and electrically connecting the electrical connection end to the circuit board when the stator-coil unit is mounted on the metal seat.

In the preferred form shown, the assembly method further comprises pulling out at least one lead wire from the circuit board along a wire channel of the metal seat when the stator-coil unit is mounted on the metal seat, thereby connecting the lead wire to an external power source or a driving circuit.

In the preferred form shown, the assembly method further comprises electrically connecting a first end of the lead wire to an electrical connection port of the circuit board, and extending a second end of the lead wire to the outside via the wire channel when the electrical connection port is aligned with the wire channel.

Further, a cooling fan including a fan frame, a circuit board, a stator-coil unit and an impeller is disclosed in another embodiment of the invention. The fan frame comprises a metal seat and a lateral wall. The metal seat comprises an engaging face and an engaging portion arranged on the engaging face. The lateral wall is arranged on a periphery of the metal seat and defines an air inlet and an air outlet. The circuit board is adhered to the engaging face of the metal seat. The circuit board comprises an insulation layer facing the metal seat. The insulation layer is in the form of a film with adhesion and insulation functions. The stator-coil unit is coupled with the fan frame and electrically connected to the circuit board. The impeller is rotatably coupled with the stator-coil unit.

Still further, an assembly method of a cooling fan is disclosed. The assembly method comprises providing a fan frame having a metal seat, providing a circuit board having an insulation layer which is adhesive and insulating, and adhering the circuit board to the metal seat when the insulation layer faces the metal seat. The assembly method further comprises mounting a stator-coil unit on the metal seat and electrically connecting the stator-coil unit to the circuit board. The assembly method further comprises rotatably coupling an impeller with the stator-coil unit.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3shows a cooling fan including a fan frame1, a circuit board2, a stator-coil unit3and an impeller4according to a preferred embodiment of the invention. The circuit board2may be mounted in the fan frame1and is electrically connected to an external power source or a driving circuit. The impeller4is rotatably coupled with the stator-coil unit3, so that the impeller4can be driven by the stator-coil unit3.

The fan frame1includes a metal seat11and a lateral wall12. The metal seat11includes an engaging face111and an engaging portion112mounted on the engaging face111. The engaging portion112has one end112aprotruding from the engaging face111. The engaging portion112may be a sleeve for coupling with the stator-coil unit3. The lateral wall12is arranged on the periphery of the metal seat11and defines an air inlet121and an air outlet122. The lateral wall12is preferably a plastic material formed on the periphery of the metal seat11by integral injection molding, thereby achieving convenient assembly and reducing the costs of the cooling fan.

The metal seat11may have a plurality of vents113to increase the quantity of air entering the fan frame1. The metal seat11also includes a wire-positioning hole114on the engaging face111. The metal seat11further includes a protrusion115extending from the periphery of the metal seat11to the edge of the wire-positioning hole114. Thus, a wire channel116may be formed on the bottom face of the protrusion115for positioning the lead wire of the circuit board2. A cover117may couple with the fan frame1. Specifically, the cover117may couple with the top edge of the lateral wall12. The cover117has a hole corresponding to the air inlet121.

The circuit board2is adhered to the engaging face111of the metal seat11. The circuit board2includes a base plate20and an insulation layer21. The insulation layer21is arranged on one face of the metal seat11facing the metal seat11. The insulation layer21is preferably in the form of a film with adhesion and insulation functions (such as a twin adhesive or resin) to firmly adhere the circuit board2to the engaging face111of the metal seat11. The circuit board2includes at least one electrical contact22to which the stator-coil unit3is electrically connected.

The circuit board2further includes a positioning hole23extending through the base plate20and the insulation layer21. The circuit board2is press fit around the engaging portion112of the metal seat11via the positioning hole23. The end112aof the engaging portion112can be forced through the positioning hole23to protrude from the circuit board2, firmly mounting the stator-coil unit3on the engaging portion112. The circuit board2may further include a lead wire24and an electrical connection port25. The lead wire24has a first end electrically connected to the electrical connection port25, as well as a second end passing through the wire-positioning hole114. The lead wire24is connected to the external power source (or the driving circuit) via the wire channel116. Thus, the lead wire24may be properly positioned in the wire channel116, achieving convenient connection between the circuit board2and the external power source (or the driving circuit).

The stator-coil unit3includes a shaft-coupling member31, a silicon steel plate unit32and a coil unit33. The shaft-coupling member31is any structure that can be rotatably coupled by the impeller4, such as a shaft tube that receives a bearing. The shaft-coupling member31has one end being a fixed end311, as shown inFIG. 4. The silicon steel plate unit32is fit around the shaft-coupling member31. An enameled copper wire is wound around a predetermined portion of the silicon steel plate unit32to form the coil unit33. The coil unit33has at least one electrical connection end331electrically connected to the at least one electrical contact22of the circuit board2.

A positioning groove34is formed between the fixed end311of the shaft-coupling member31and the silicon steel plate unit32, as shown inFIG. 4. Therefore, when the fixed end311of the shaft-coupling member31is coupled with the engaging portion112of the metal seat11, the end112aof the engaging portion112may be forced into the positioning groove34. This firmly mounts the stator-coil unit3on the fan frame1to obtain reinforced coupling between the stator-coil unit3and the fan frame1.

The impeller4is rotatably coupled with the shaft-coupling member31of the stator-coil unit3. The impeller4has a shaft and a permanent magnet, with the shaft rotatably coupled with the shaft-coupling member31. There is an air gap between the permanent magnet and the stator-coil unit3. When the stator-coil unit3is electrically connected to the external power source (or the driving circuit), the stator-coil unit3generates magnetic fields that react with the permanent magnet through the air gap, driving the impeller4to rotate. Thus, a cooling effect is provided.

Referring toFIG. 5, an assembly method of the cooling fan includes a circuit board assembly step S1, a stator-coil unit positioning step S2and a final assembly step S3.

As shown inFIGS. 5 and 6, the circuit board assembly step S1is configured to provide the fan frame1with the metal seat11. The circuit board2may be press fit around the engaging portion112of the metal seat11via the positioning hole23. Alternatively, the circuit board2may be adhered to the engaging face111of the metal seat11. The circuit board2can be rapidly mounted on the metal seat11either way. If the circuit board2is adhered to the engaging face111of the metal seat11via the insulation layer21, the insulation layer21may be arranged on the bottom face of the circuit board2before the circuit board2is adhered to the metal seat11. Alternatively, the insulation layer21may also be arranged on the metal seat11before the circuit board2is adhered to the metal seat11. Moreover, the circuit board assembly step S1may be further configured to align the electrical connection port25of the circuit board2with the wire channel116, and to pull the lead wire24along the wire channel116to be connected to the external power source (or the driving circuit).

Referring toFIGS. 5 and 7, the stator-coil unit positioning step S2is configured to provide the shaft-coupling member31, so that the silicon steel plate unit32, which is wound with the coil unit33, will be coupled with the outer circumferential face of the shaft-coupling member31. Moreover, the electrical connection end331may be pulled out from the coil unit33in advance and kept aside for future connection to the electrical contact22of the circuit board2. Finally, the stator-coil unit3consisting of the shaft-coupling member31, the silicon steel plate unit32and the coil unit33is fit around the engaging portion112of the metal seat11. At this time, the electrical connection end331can be electrically connected to the electrical contact22of the circuit board2.

Referring toFIGS. 5 and 8, the final assembly step S3is configured to rotatably couple the impeller4with the shaft-coupling member31of the stator-coil unit3. Then, the cover117is preferably fixed on the top edge of the lateral wall12to complete the assembly procedure of the cooling fan, as shown inFIG. 4.

The embodiments of the invention are able to achieve many advantages based on the disclosed structures of the cooling fan, as well as based on the assembly method of the cooling fan, as described in detail below.

In one embodiment of the invention, since the stator-coil unit3can be mounted on the metal seat11after the circuit board2is mounted on the metal seat11, the cooling fan of the invention will have a simplified assembly procedure and a convenient assembly. In contrast, the conventional cooling fan8has a troublesome assembly procedure due to the fact that the circuit board822must be coupled with the stator821before the assembled stator811and circuit board822are mounted on the seat811.

During the assembly process, since the circuit board2is mounted on the metal seat11in advance, the enameled copper wire of the electrical connection end331can be properly arranged in a manner that allows the electrical connection end331of the coil unit33to be easily connected to the electrical contact22of the circuit board2when the stator-coil unit3is mounted on the metal seat11. Thus, the enameled copper wire will be arranged in convenience. The enameled copper wire will also be connected to the electrical contact22in convenience.

In the assembly method of the cooling fan, the lead wire24of the circuit board2is guided to the external power source (or the driving circuit) through the wire channel116, rapidly arranging and positioning the lead wire24.

In addition, one embodiment of the invention is able to provide improved insulation between the metal seat11and the circuit board2through the insulation layer21therebetween.

Furthermore, the circuit board2can be mounted on the engaging face111of the metal seat11when the circuit board2is press fit around the engaging portion112of the metal seat11via the positioning hole23. Alternatively, when the circuit board2is adhered to the metal seat11via the insulation layer21, the height of the cooling fan is reduced, and convenient assembly of the cooling fan is achieved.