Electric Grinding Machine

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

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.

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.

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

Please refer to., and. The invention provides an electric grinding machine, which is a hand tool machine. The electric grinding machineincludes a housing, an electric motor, a motor end plate, and an airflow generating member. The housingis hollow and formed with at least one inlet hole. The electric motoris disposed in the housing; specifically, the electric motoris fixed to the motor end plate, and The electric motoris placed into the housingwhile the motor end plateis assembled with the housing. In addition to fixing the electric motorin the housing, the motor end platealso closes the electric motorpartially to restrict entries of external materials into the electric motor. The motor end plateis formed with at least one openingand at least one first annular structure, the at least one openingis not shielded by the electric motorand passes through the motor end plate. The at least one openingmay be a through hole, or a hollow portion of the motor end plate. The at least one first annular structureis disposed at a side of the motor end platedistanced from the electric motor. In one embodiment, a position of the at least one first annular structureis relative to a part of the electric motorclosed by the motor end plate.

Please refer to. The airflow generating memberis connected to the electric motor. The airflow generating memberis formed with at least one second annular structure, the at least one second annular structureis matched with the at least one first annular structure, and the at least one second annular structureand the at least one first annular structuremay be an annular wall or an annular slot, respectively. When the electric grinding machineis assembled, a gapis formed between the at least one second annular structureand the at least one first annular structure, and further a plurality of dust-blocking pointsin the gapare jointly defined by the at least one second annular structureand the at least one first annular structure. The plurality of dust-blocking pointsare located at turning points of the gapto achieve a dust-blocking effect by a non-straight path.

Please refer toand. The airflow generating memberrotates along with the electric motor, and a heat dissipation airflowis generated by rotation of the airflow generating memberin the housing. The heat dissipation airflowenters from the at least one inlet hole, flows through a surface of the electric motorand the at least one openingto the airflow generating member, and then exhausts from the housing. It should be understood that the gapformed by the at least one first annular structureand the at least one second annular structureis not located on a main path of the heat dissipation airflow. The heat dissipation airflowof the invention flowing through the surface of the electric motoreffectively reduces temperatures of the electric motorand improves a holding comfort of the user. Dust entrained by the heat dissipation airflowcannot enter from the surface of the electric motor, nor can dust entrained by the heat dissipation airflowenter the electric motorfrom between the airflow generating memberand the motor end plate. By the aforementioned design, the invention achieves a purpose of being dust-proof without affecting a movement of the airflow generating memberor additional disposal of other components. Furthermore, through the aforementioned structure, the invention makes a structure of the electric grinding machinemore compact and effectively reduces a volume thereof.

Please refer to. In an embodiment, a number of the at least one first annular structureand a number of the at least one second annular structureare 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 structureis one, and the number of the at least one first annular structureis two. One second annular structureand two first annular structuresare arranged at intervals, and the one second annular structureis located between the two first annular structures. The plurality of dust-blocking pointsare distributed at the turning points of the gapformed by the two first annular structuresand the one second annular structure. Furthermore, one of the two first annular structurescan be used to secure a bearing.

Please refer to. In an embodiment, through structural design, the at least one first annular structuredoes not contact the airflow generating member, and the at least one second annular structuredoes not contact the motor end plate. Further, the airflow generating memberis disposed between an eccentric blockand the motor end plate. Further, the airflow generating memberis located on the eccentric block, thereby ensuring that the at least one first annular structuredoes not contact the airflow generating member, and the at least one second annular structuredoes not contact the motor end plate. Based on the above, the eccentric blockis connected to a rotating shaftand is provided with a tool holderdisposed therein, the tool holderis provided for assembling a grinding disc. The tool holderrotates when the electric motorrotates, thereby driving the grinding discto rotate.

Please refer toand. In an embodiment, the airflow generating memberincludes a baseand a plurality of fan bladesdisposed on the base. The plurality of fan bladesare disposed on a surface of the basesame as the at least one second annular structure, and closer to an edge of the basethan the at least one second annular structure.

Please refer to. In an embodiment, the at least one openingis disposed close to a surface edge of the electric motorto minimize turbulence of the heat dissipation airflowgenerated here. In one embodiment, the motor end plateis formed with a plurality of openings, the plurality of openingsare disposed along the surface edge of the electric motor, and the plurality of openingscan be disposed at intervals in an equally-spaced manner. On the other hand, the at least one first annular structureis arranged within a projection range of the electric motor. Furthermore, the at least one first annular structureis located at the portion of the motor end platewhich closes the electric motor.

Please refer toand. The electric motorincludes a rotorand a statordisposed around the rotor. In one embodiment, a part of the statoris exposed on the surface of the electric motor. That is to say, the heat dissipation airflowdissipates heat for the statordirectly Please refer toand. The electric grinding machineincludes a control circuit boarddisposed in the housingand connected to the electric motor. In an embodiment, a position of the at least one inlet holeis arranged close to the control circuit board, so that the heat dissipation airflowpasses through the control circuit boardto dissipate heat from electronic components on the control circuit board.

Please refer toand. In an embodiment, the housingincludes an outlet holefacing the airflow generating member, and the outlet holeserves as an end of the heat dissipation airflowin the housing. In addition, exhausting the heat dissipation airflowof the invention may also be implemented in other ways, such as exhausting through a gapbetween the grinding discand a dust cover.