ELECTRIC GRINDING MACHINE

Description

FIELD OF THE INVENTION

The invention relates to an electric grinding machine, and more particularly to an electric grinding machine with a dust-proof design.

BACKGROUND OF THE INVENTION

One of the most criticized problems of electric grinding machines is that heat generated by an electric motor or a control circuit board under a prolonged grinding operation will easily cause a user's palms to feel high temperatures, which makes it difficult to sustain the use of the machine.

Although there are many solutions to this problem, such as disclosed by CN106392836B, TWI796281, due to the fact that the electric motor needs to be equipped with a motor end plate to limit an entry of dust, a position of an airflow generating member is restricted.

SUMMARY OF THE INVENTION

A main object of the invention is to solve the problem that structures of conventional electric grinding machines.

In order to achieve the above objects, the invention provides an electric grinding machine, including a housing, an electric motor, a motor end, and an airflow generating member. The housing is formed with at least one inlet hole. The motor end plate is formed with at least one opening and at least one first structure, the at least one opening does not be shielded by the electric motor, and the at least one first annular structure is disposed at a side distanced from the electric motor. The airflow generating member rotates with the electric motor, the airflow generating member generates a heat dissipation airflow in the housing, and the heat dissipation airflow enters from the at least one inlet hole, flows through a surface of the electric motor, and passes through the at least one opening to a position of the airflow generating member. The airflow generating member is formed with at least one second annular structure matched with the at least one first annular structure, and a plurality of dust-blocking points are jointly defined by the at least one first annular structure and the at least one second annular structure.

In one embodiment, a number of the at least one first annular structure and a number of the at least one second annular structure are N and N+1, respectively, and N is greater than or equal to one.

In one embodiment, the airflow generating member includes a base and a plurality of fan blades disposed on the base, the plurality of fan blades is disposed on a face of the base same as the at least one second annular structure, and the plurality of fan blades is closer to an edge of the base than the at least one second annular structure.

In one embodiment, the at least one opening is disposed close to a surface edge of the electric motor, and the at least one first annular structure is arranged within a projection range of the electric motor.

In one embodiment, the electric motor includes a rotor and a stator disposed around the rotor, and a part of the stator is exposed on the surface of the electric motor.

In one embodiment, the electric grinding machine includes a control circuit board disposed in the housing and connected to the electric motor, and at least one inlet hole is disposed close to the control circuit board.

In one embodiment, the housing includes an outlet hole facing the airflow generating member.

In one embodiment, the airflow generating member is disposed between an eccentric block and the motor end plate.

In one embodiment, the at least first annular structure is not in contact with the airflow generating member, and the at least second annular structure is not in contact with the motor end plate.

Through the aforementioned implementation of the invention, the invention has the following characteristics compared with the prior art. The heat dissipation airflow of the invention passes through the surface of the electric motor, which can effectively reduce temperature of the electric motor and increase the user's holding comfort. The dust entrained by the heat dissipation airflow cannot enter from the surface of the electric motor, nor can the dust entrained by the heat dissipation airflow enter the electric motor from between the airflow generating member and the motor end plate. Through the design of the at least first annular structure and the at least second annular structure, the invention achieves a purpose of being duct-proof without affecting a movement of the airflow generating member or additional disposal of other components. Furthermore, through the aforementioned structure, the invention makes a structure of the electric grinding tool more compact and effectively reduces a volume thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section view of an embodiment of an electric grinding machine of the invention.

FIG. 2 is an exploded view of a portion of an embodiment of the electric grinding machine of the invention.

FIG. 3 is a structural view of a motor end plate and an airflow generating member of an embodiment of the electric grinding machine of the invention.

FIG. 4 is a cross-section view of a portion of an embodiment of the electric grinding machine of the invention.

FIG. 5 is a first airflow path diagram of an embodiment of the electric grinding machine of the invention.

FIG. 6 is a second airflow path diagram of an embodiment of the electric grinding machine of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description and technical content of the invention are described below with reference to the accompanying drawings.

Please refer to FIG. 1. FIG. 2, and FIG. 3. The invention provides an electric grinding machine 20, which is a hand tool machine. The electric grinding machine 20 includes a housing 21, an electric motor 22, a motor end plate 23, and an airflow generating member 24. The housing 21 is hollow and formed with at least one inlet hole 211. The electric motor 22 is disposed in the housing 21; specifically, the electric motor 22 is fixed to the motor end plate 23, and The electric motor 22 is placed into the housing 21 while the motor end plate 23 is assembled with the housing 21. In addition to fixing the electric motor 22 in the housing 21, the motor end plate 23 also closes the electric motor 22 partially to restrict entries of external materials into the electric motor 22. The motor end plate 23 is formed with at least one opening 231 and at least one first annular structure 232, the at least one opening 231 is not shielded by the electric motor 22 and passes through the motor end plate 23. The at least one opening 231 may be a through hole, or a hollow portion of the motor end plate 23. The at least one first annular structure 232 is disposed at a side of the motor end plate 23 distanced from the electric motor 22. In one embodiment, a position of the at least one first annular structure 232 is relative to a part of the electric motor 22 closed by the motor end plate 23.

Please refer to FIG. 4. The airflow generating member 24 is connected to the electric motor 22. The airflow generating member 24 is formed with at least one second annular structure 241, the at least one second annular structure 241 is matched with the at least one first annular structure 232, and the at least one second annular structure 241 and the at least one first annular structure 232 may be an annular wall or an annular slot, respectively. When the electric grinding machine 20 is assembled, a gap 30 is formed between the at least one second annular structure 241 and the at least one first annular structure 232, and further a plurality of dust-blocking points 311 in the gap 30 are jointly defined by the at least one second annular structure 241 and the at least one first annular structure 232. The plurality of dust-blocking points 311 are located at turning points of the gap 30 to achieve a dust-blocking effect by a non-straight path.

Please refer to FIG. 5 and FIG. 6. The airflow generating member 24 rotates along with the electric motor 22, and a heat dissipation airflow 31 is generated by rotation of the airflow generating member 24 in the housing 21. The heat dissipation airflow 31 enters from the at least one inlet hole 211, flows through a surface of the electric motor 22 and the at least one opening 231 to the airflow generating member 24, and then exhausts from the housing 21. It should be understood that the gap 30 formed by the at least one first annular structure 232 and the at least one second annular structure 241 is not located on a main path of the heat dissipation airflow 31. The heat dissipation airflow 31 of the invention flowing through the surface of the electric motor 22 effectively reduces temperatures of the electric motor 22 and improves a holding comfort of the user. Dust entrained by the heat dissipation airflow 31 cannot enter from the surface of the electric motor 22, nor can dust entrained by the heat dissipation airflow 31 enter the electric motor 22 from between the airflow generating member 24 and the motor end plate 23. By the aforementioned design, the invention achieves a purpose of being dust-proof without affecting a movement of the airflow generating member 24 or additional disposal of other components. Furthermore, through the aforementioned structure, the invention makes a structure of the electric grinding machine 20 more compact and effectively reduces a volume thereof.

Please refer to FIG. 4. In an embodiment, a number of the at least one first annular structure 232 and a number of the at least one second annular structure 241 are N and N+1, respectively, wherein N is greater than or equal to one. Taking the drawings of the invention as an example, the number of the at least one second annular structure 241 is one, and the number of the at least one first annular structure 232 is two. One second annular structure 241 and two first annular structures 232 are arranged at intervals, and the one second annular structure 241 is located between the two first annular structures 232. The plurality of dust-blocking points 311 are distributed at the turning points of the gap 30 formed by the two first annular structures 232 and the one second annular structure 241. Furthermore, one of the two first annular structures 232 can be used to secure a bearing 25.

Please refer to FIG. 4. In an embodiment, through structural design, the at least one first annular structure 232 does not contact the airflow generating member 24, and the at least one second annular structure 241 does not contact the motor end plate 23. Further, the airflow generating member 24 is disposed between an eccentric block 224 and the motor end plate 23. Further, the airflow generating member 24 is located on the eccentric block 224, thereby ensuring that the at least one first annular structure 232 does not contact the airflow generating member 24, and the at least one second annular structure 241 does not contact the motor end plate 23. Based on the above, the eccentric block 224 is connected to a rotating shaft 221 and is provided with a tool holder 26 disposed therein, the tool holder 26 is provided for assembling a grinding disc 27. The tool holder 26 rotates when the electric motor 22 rotates, thereby driving the grinding disc 27 to rotate.

Please refer to FIG. 3 and FIG. 4. In an embodiment, the airflow generating member 24 includes a base 242 and a plurality of fan blades 243 disposed on the base 242. The plurality of fan blades 243 are disposed on a surface of the base 242 same as the at least one second annular structure 241, and closer to an edge of the base 242 than the at least one second annular structure 241.

Please refer to FIG. 4. In an embodiment, the at least one opening 231 is disposed close to a surface edge of the electric motor 22 to minimize turbulence of the heat dissipation airflow 31 generated here. In one embodiment, the motor end plate 23 is formed with a plurality of openings 231, the plurality of openings 231 are disposed along the surface edge of the electric motor 22, and the plurality of openings 231 can be disposed at intervals in an equally-spaced manner. On the other hand, the at least one first annular structure 232 is arranged within a projection range of the electric motor 22. Furthermore, the at least one first annular structure 232 is located at the portion of the motor end plate 23 which closes the electric motor 22.

Please refer to FIG. 3 and FIG. 4. The electric motor 22 includes a rotor 222 and a stator 223 disposed around the rotor 222. In one embodiment, a part of the stator 223 is exposed on the surface of the electric motor 22. That is to say, the heat dissipation airflow 31 dissipates heat for the stator 223 directly Please refer to FIG. 1 and FIG. 6. The electric grinding machine 20 includes a control circuit board 28 disposed in the housing 21 and connected to the electric motor 22. In an embodiment, a position of the at least one inlet hole 211 is arranged close to the control circuit board 28, so that the heat dissipation airflow 31 passes through the control circuit board 28 to dissipate heat from electronic components on the control circuit board 28.

Please refer to FIG. 4 and FIG. 6. In an embodiment, the housing 21 includes an outlet hole 212 facing the airflow generating member 24, and the outlet hole 212 serves as an end of the heat dissipation airflow 31 in the housing 21. In addition, exhausting the heat dissipation airflow 31 of the invention may also be implemented in other ways, such as exhausting through a gap 32 between the grinding disc 27 and a dust cover 29.