TW202419224A - Electric grinding machine tools and their housings - Google Patents

Abstract

An electric grinding machine tool includes an electric motor, an airflow generating member, and a housing. The housing includes a hollow housing, a motor shield located in the hollow housing, two partitions located between the side walls of the motor shield and the hollow housing, at least one air outlet facing the airflow generating member, a first air inlet formed on the hollow housing, and at least one second air inlet formed on the hollow housing and spaced from the first air inlet. When the airflow generating member is activated, the first air inlet generates a pressure difference at an air inlet portion of the hollow housing near the motor shield to cause air to enter the second air inlet.

Description

Electric grinding machine tools and their housings

The present invention relates to an electric grinding machine tool, in particular to an electric grinding machine tool with a housing designed with a large air intake volume.

The existing electric grinding tool generally has an airflow generating member attached to an eccentric block, and the airflow generating member is used to generate airflow for internal heat dissipation, and discharge the waste heat generated by an electric motor or a circuit board when working. One implementation scheme is disclosed in EP2132000B1, or can refer to FIG1. In the technical scheme disclosed in FIG1, a grinding plate shield 61 of the electric grinding tool 60 is provided with a plurality of vents 611 arranged at intervals on the side, and the airflow generating member 62 is arranged close to the vents 611, and at the same time close to the port connecting the grinding plate shield 61 and a tool housing 63. Ideally, when the airflow generating member 62 rotates, air will be introduced from the vents 611 to dissipate heat. However, due to the following reasons: the vents 611 are arranged at intervals (as shown in FIG. 2 ), and the airflow generating member 62 is too close to the vents 611, the vents 611 cannot actually produce the expected effect. When one of the vents 611 is used for intake, another of the vents 611 that follows will produce exhaust, resulting in a short circuit. Due to the short-circuit problem (also known as short cycle), the air intake efficiency of the vents 611 does not meet expectations, and the heat dissipation effect of the airflow generating element 62 is limited to the eccentric block. Although the eccentric block is connected to the electric motor 64 and can conduct the waste heat, the shaft diameter of the shaft connecting the eccentric block and the electric motor 64 is too small, and the waste heat transfer speed is not as fast as the waste heat generation speed of the electric motor 64, resulting in continuous accumulation of waste heat, thereby affecting the user's feeling of holding the tool housing 63.

Furthermore, although the tool housing 63 is provided with a plurality of air inlets 631, the air pressure difference generated in the tool housing 63 when the airflow generating member 62 rotates is used to attract external air to enter through the air inlets 631 and generate airflow. However, as can be seen from the above, the airflow generating member 62 has a poor efficiency problem and cannot generate the required suction force, which will affect the air volume entering through the air inlets 631, and cannot effectively dissipate the heat of the electric motor 64, and the electric motor 64 still has a serious waste heat accumulation condition. Furthermore, in order to allow the airflow flowing in the tool housing 63 to pass through the location of the electric motor 64, the air inlet holes 631 in the tool housing 63 will not be directly close to the airflow generating part 62. In other words, there is a certain distance between the air inlet holes 631 and the airflow generating part 62, and the suction force is also attenuated due to the distance. In this way, the airflow generating part 62 alone cannot effectively generate a large amount of airflow in the tool housing 63.

The only solution to the problem of heat accumulation in electric grinding tools is to equip an electric grinding tool 70 with an active dust suction structure 71, as shown in FIG3 or EP2946710B1. As shown in FIG3, the air inlet of the active dust suction structure 71 is a suction port 721 opened on a grinding plate shield 72. When implemented, the active dust suction structure 71 will generate suction force in the space inside the grinding plate shield 72. The suction force is significantly greater than the suction force generated by an air flow generating member 73, and a plurality of air inlet holes 741 on a tool housing 74 inhale a large amount of gas. The large amount of gas sucked from the air inlet holes 741 is of great help to dissipate the heat of an electric motor 75.

However, not all electric grinding tools can be equipped with the active vacuum structure, and a solution to the heat accumulation of the electric motor when the electric grinding tool is not equipped with the active vacuum structure is still urgently needed.

The main purpose of the present invention is to solve the airflow design problem of the housing of a conventional electric grinding tool.

The secondary purpose of the present invention is to solve the problem that the electric motor of the conventional electric grinding machine tool has heat accumulation and is difficult to discharge.

To achieve the above-mentioned object, the present invention provides an electric grinding machine tool, comprising an electric motor, an airflow generating member, and a housing. The airflow generating member rotates when the electric motor is started, and the housing comprises a hollow housing, a motor shield disposed in the hollow housing and providing the electric motor, two partitions disposed between a side wall of the motor shield and the hollow housing, at least one side facing the air outlet of the airflow generating member, at least one first air inlet formed on the hollow housing, and at least one first air inlet formed on the hollow housing and connected to the first air inlet. The motor shield is provided with a second air inlet separated by a second air inlet, the connection line of the two partitions divides the motor shield into an air inlet portion and an air outlet portion connected to the air inlet portion, the air outlet is close to the air outlet portion, the first air inlet faces the air inlet portion of the motor shield, and when the airflow generating element is started, the first air inlet generates a pressure difference at the air inlet portion close to the motor shield in the hollow outer shell to cause air to enter the second air inlet.

In one embodiment, the motor shield includes a top surface connected to the side wall, and the two partitions are connected to the side wall and allow the airflow to pass through the top surface.

In one embodiment, two auxiliary partitions cooperating with the two partitions are disposed in the hollow outer shell.

In one embodiment, the electric grinding tool includes a circuit board disposed in the housing and electrically connected to the electric motor, the housing has a grip portion on which the electric motor is mounted, and a holding portion on which the circuit board is mounted and extends from the grip portion, the first air inlet is located in the grip portion, and the second air inlet is located in the holding portion and faces the circuit board.

In one embodiment, the grip portion includes a head section and a neck section extending from the head section and close to the airflow generating member, and the first air inlet is close to the position where the neck section is connected to the grip portion.

In one embodiment, the air inlet position of the second air inlet is lower than the air inlet position of the first air inlet.

In one embodiment, the housing is composed of a plurality of housing parts, one of which is formed with the motor cover, the two partitions, the air outlet, the first air inlet and the second air inlet.

In one embodiment, the air outlet is arranged along the edge of the motor cover.

In addition to the above, the present invention also provides a housing of an electric grinding tool, comprising a hollow outer shell, a motor shield, two partitions, at least one air outlet, at least one first air inlet and at least one second air inlet. The motor shield is located in the hollow outer shell, the two partitions are located between the side wall of the motor shield and the hollow outer shell, and the two partitions are located on two opposite sides of the motor shield. The air outlet is formed on one of the hollow shell and the outer edge of the motor shield, the first air inlet is formed on the hollow shell, the first air inlet and the air outlet are respectively located on both sides of the two partitions, the first air inlet faces the motor shield and is close to one of the two partitions, the second air inlet is formed on the hollow shell, the second air inlet and the first air inlet are located on the same side of the two partitions, and the distance from the second air inlet to the air outlet is greater than the distance from the first air inlet to the air outlet.

In one embodiment, two auxiliary partitions cooperating with the two partitions are disposed in the hollow outer shell.

In one embodiment, the hollow housing is divided into a grasping portion and a gripping portion extending from the grasping portion, the first air inlet is located at the grasping portion, and the second air inlet is located at the gripping portion.

In one embodiment, the grip portion includes a head section and a neck section extending from the head section, and the first air inlet is close to the position where the neck section is connected to the grip portion.

In one embodiment, the air inlet position of the second air inlet is lower than the air inlet position of the first air inlet.

In one embodiment, the hollow housing is formed by a plurality of housing components, one of which forms part of the hollow housing, the motor shield, the two partitions, the air outlet, the first air inlet and the second air inlet.

In one embodiment, the air outlet is arranged along the edge of the motor cover.

Through the above implementation of the present invention, compared with the conventional use, the following features are provided: the first air inlet of the present invention is affected by the airflow generating element before the second air inlet, and a pressure difference is generated at the air inlet portion of the hollow housing near the motor shield, causing the second air inlet to inlet air, specifically improving the problem that the airflow in the housing is generated solely by the suction force of the airflow generating element in the past, and the airflow is easily insufficient to dissipate heat inside the housing. The first air inlet and the second air inlet of the present invention inlet air together, so that a large airflow can be generated inside the housing, increasing heat exchange with the motor shield, and effectively removing the accumulated waste heat generated by the operation of the electric motor from the motor shield. In addition, the present invention allows the airflow to completely pass through the top surface of the motor shield through the two partitions, so that the temperature rise of the part of the hollow shell provided for the user to hold is no longer drastic, which greatly increases the comfort of the user's palm when holding and using for a long time.

The detailed description and technical contents of the present invention are as follows with reference to the accompanying drawings:

Referring to FIGS. 4 to 7 , the present invention provides an electric grinding machine tool 20, comprising a housing 21, an electric motor 23, an airflow generating member 24, and a grinding disc 25. The housing 21 comprises a hollow housing 211, a motor shield 212 for mounting the electric motor 23, two partitions 213, at least one air outlet 214, at least one first air inlet 215, and at least one second air inlet 216. The hollow housing 211 can be formed by assembling a plurality of housing parts 217, the motor shield 212 is located in the hollow housing 211, and the motor shield 212 can be a component directly formed from one of the housing parts 217. The motor shield 212 of the present invention is not tightly attached to the inner wall of the hollow shell 211, so that the shell 21 forms a ventilation gap 218 between the hollow shell 211 and the motor shield 212. In addition, the two partitions 213 are located between the side walls of the motor shield 212 and the hollow shell 211. More specifically, the two partitions 213 are located on two opposite sides of the motor shield 212. The two partitions 213 are located in the ventilation gap 218, but it should be understood that the two partitions 213 do not completely divide the ventilation gap 218 into two areas, and the two partitions 213 are only used to guide the airflow to flow to the part not blocked by the two partitions 213. Specifically, the motor shield 212 includes a side wall 219 and a top surface 220 connected to the side wall 219. The two partitions 213 are connected to the side wall 219 and allow airflow to pass through the top surface 220. Furthermore, the connection line of the two partitions 213 divides the motor shield 212 into an air inlet portion 221 and an air outlet portion 222, and the air inlet portion 221 is still connected to the air outlet portion 222.

On the other hand, please refer to FIG. 6 and FIG. 7 , the air outlet 214 of the present invention faces the airflow generating member 24, and the air outlet 214 is formed on one of the outer edges of the hollow shell 211 and the motor shield 212. The air outlet 214 is disposed near the air outlet portion 222 of the motor shield 212, and the first air inlet 215 corresponds to the air inlet portion 221 of the motor shield 212. In other words, the air outlet 214 and the first air inlet 215 are located on both sides of the two partitions 213, respectively. Moreover, the air outlet 214 is the outlet of the airflow in the shell 21, and the airflow generating member 24 draws the gas in the hollow shell 211 from the air outlet 214, so that the gas flows in the shell 21, generating an airflow. In one embodiment, the air outlet 214 is disposed along an edge of the motor cover 212 .

Referring again to FIG. 5 and FIG. 6 , the first air inlet 215 is formed on the hollow housing 211 and faces the motor shield 212. The first air inlet 215 is close to one of the two partitions 213. Moreover, the second air inlet 216 and the first air inlet 215 are located on the same side of the two partitions 213. The second air inlet 216 and the first air inlet 215 are formed in the hollow housing 211 at intervals. The distance from the second air inlet 216 to the air outlet 214 is greater than the distance from the first air inlet 215 to the air outlet 214. As mentioned above, please refer to FIG. 6, FIG. 8 and FIG. 9. When the present invention is implemented, the first air inlet 215 is closer to the air outlet 214 and is affected by the airflow generating member 24 before the second air inlet 216. It can be said that the first air inlet 215 generates air intake first (as indicated by 261 in FIG. 8). The air intake of the first air inlet 215 will generate a pressure difference at the air intake portion 221 near the motor shield 212 in the middle shell outer shell 211. The aforementioned air pressure difference will act on the second air inlet 216, causing the air intake of the second air inlet 216 (as indicated by 262 in FIG. 8). Accordingly, the problem that the airflow in the shell is generated solely by the suction of the airflow generating member in the past, which is easy to make the airflow insufficient to cope with the heat dissipation inside the shell, is specifically improved. Referring again to FIG. 7 to FIG. 9 , the first air inlet 215 and the second air inlet 216 of the present invention simultaneously take in air, which can generate a large air flow inside the housing 21, increase the heat exchange with the motor shield 212, and effectively remove the accumulated waste heat generated by the operation of the electric motor 23 from the motor shield 212. In addition, the present invention further allows the air flow to completely pass through the top surface 220 of the motor shield 212 through the two partitions 213, so that the waste heat on the motor shield 212 is effectively discharged, greatly increasing the comfort of the palm of the user when holding and using for a long time.

Please refer to Table 1 and Table 2. Table 1 is a temperature rise comparison table of the electric grinding tool 20 of the present invention (referred to as the present invention in the table), the conventional electric grinding tool without an active dust suction structure (referred to as conventional without dust suction in the table), and the electric grinding tool with an active dust suction structure (referred to as conventional with dust suction in the table). The temperature measurement point is the user's palm grip (such as 40 marked in Figure 4), and the setting conditions are load 180W, sandpaper #80, and grinding disc 6 inches. The basic conditions of Table 2 are the same as those of Table 1, and the only difference is that the temperature measurement point is the user's finger grip (such as 41 marked in Figure 4).

Table I Ambient temperature Machine tool operating time 10 minutes 15 minutes 20 minutes 25 minutes 30 minutes The invention 22.3 28.8 30.9 31.7 31.8 31.7 Use no dust 22.8 37.4 43.3 48.1 51.9 53.1 Use a vacuum cleaner 21.8 31.9 31.4 32.3 31.0 32.0

Table II Ambient temperature Machine tool operating time 10 minutes 15 minutes 20 minutes 25 minutes 30 minutes The invention 22.3 24.8 25.2 24.9 24.4 24.3 Use no dust 22.8 45.1 51.8 54.7 62.3 61.1 Use a vacuum cleaner 21.8 27.9 28.9 28.1 29.2 28.9

It can be understood from Table 1 and Table 2 that when the vacuum cleaner is used continuously for 15 minutes, the temperature rise of the palm measurement point and the finger grip measurement point is obvious. Since the temperature measured from the outside of the machine tool is so high, it is conceivable that the temperature inside the machine tool is even higher, which highlights the problem of waste heat accumulation derived from the use of the internal parts of the shell because the airflow generated in the shell of the existing machine tool is insufficient to dissipate the heat of the shell. On the other hand, the electric grinding machine tool 20 of the present invention has no dramatic temperature rise during multiple testing times, which shows that the design of the first air inlet 215 and the second air inlet 216 of the present case does achieve the purpose of coordinated air intake, so that the airflow flowing in the shell 21 is increased, and the waste heat generated by the operation of the electric motor 23 is quickly taken out. On the other hand, the temperature change at the palm measurement point further highlights that the two partitions 213 of the present invention allow the airflow to completely pass through the top surface 220 of the motor shield 212, so that the temperature rise of the part of the hollow shell 211 provided for the user to hold is no longer drastic, greatly increasing the comfort of the user's palm when holding and using for a long time.

Next, by comparing the temperature of the present invention and the temperature of the conventional vacuum cleaner during the operation of multiple machine tools, it can be clearly found that the present invention, when not equipped with an active vacuum cleaner structure, has a palm measurement point and a finger grip measurement point temperature comparable to that of the conventional vacuum cleaner, and also has a significantly better performance than the conventional vacuum cleaner at the finger grip measurement point (Table 2). It can be said that the present invention has indeed improved the problem of heat accumulation of the electric motor 23 that the conventional structure has not been able to solve.

Referring again to FIG. 4 , FIG. 5 and FIG. 7 , in one embodiment, the electric grinding tool 20 includes a circuit board 27, which is disposed in the housing 21 and electrically connected to the electric motor 23. The housing 21 can be divided into a grip portion 223 on which the electric motor 23 is mounted, and a grip portion 224 on which the circuit board 27 is mounted and extends from the grip portion 223. The first air inlet 215 is located at the grip portion 223, and the second air inlet 216 is located at the grip portion 224 and faces the circuit board 27. Further, the grip portion 223 can include a head section 225, and a neck section 226 extending from the head section 225 and close to the airflow generating member 24. The head section 225 mainly faces the palm of the user when the user holds the device, and the neck section 226 is provided for the user to grip the device with fingers. The first air inlet 215 is located near the connection between the neck section 226 and the gripping portion 224 .

Referring again to FIG. 5 , in one embodiment, the hollow housing 211 is formed by the housing components 217 , one of which forms a portion of the hollow housing 211 , the motor shield 212 , the two partitions 213 , the air outlet 214 , the first air inlet 215 , and the second air inlet 216 .

Referring again to FIG. 6 , the first air inlet 215 of the present invention may be implemented in plural numbers. The plural first air inlets 215 may be symmetrically disposed on the left and right sides of the housing 21 about a central axis 228 of the housing 21 .

Referring again to Fig. 9, in one embodiment, the air inlet position of the second air inlet 216 is lower than the air inlet position of the first air inlet 215. Referring again to Fig. 6, in one embodiment, two auxiliary baffles 229 cooperating with the two baffles 213 are disposed in the hollow housing 211.

Referring to FIG. 5 , the electric grinding tool 20 of the present invention comprises an eccentric block 28 connected to the electric motor 23, and a grinding disc shield 29. The eccentric block 28 is stepped and has a first portion 281, and a second portion 282 located below the first portion 281 and offset from the axis of the first portion 281. The airflow generating member 24 is attached to the eccentric block 28 and is located in the space defined by the grinding disc shield 29. Furthermore, the airflow generating member 24 is hung on the second portion 282 of the eccentric block 28, and the bottom edge of the airflow generating member 24 is equal to or slightly higher than the bottom edge of the second portion 282 of the eccentric block 28. Furthermore, the airflow generating member 24 includes a substrate 241 and blades 242 disposed on the substrate 241. The blades 242 have the same shape and are only disposed on a surface of the substrate 241 facing the eccentric block 28. The blades 242 are disposed at intervals and arranged in a circle on the substrate 241. In one embodiment, in order to more smoothly introduce a large amount of gas into the housing 21, the airflow generating member 24 is arranged in the space defined by the grinding disk mask 29 based on the following conditions: the distance between the top edge of each of the fan blades 242 and the housing 21 (as indicated by 42 in FIG. 10 ) is greater than 50% of the longitudinal height of each of the fan blades 242, the distance between the outer edge of each of the fan blades 242 and the grinding disk mask 29 (as indicated by 43 in FIG. 10 ) is greater than 50% of the radial width of each of the fan blades 242, and the outer diameter of the airflow generating member 24 is greater than the distance from the air outlet 214 to the center of the motor mask 212. Based on the above conditions, the airflow generating member 24 of the present embodiment is not closely attached to the housing 21 and the grinding disc shield 29, and an airflow temporary storage area 30 can be generated. The airflow temporary storage area 30 can keep the air guiding effect of the airflow generating member 24 smooth.

Please refer to Figures 10 to 12, the grinding disc shield 29 is assembled with the housing 21 and covers the airflow generating member 24 therein. The grinding disc shield 29 includes a shield body 291, a combination interface 292 formed at one end of the shield body 291, and a release port 293 formed at the other end of the shield body 291. The grinding disc shield 29 does not have a vent other than the combination interface 292 and the release port 293. The combination interface 292 and the release port 293 are coaxially arranged, that is, the combination interface 292 and the release port 293 are arranged opposite to each other. In order to prevent the airflow from accidentally hitting the surface of the grinding disc 25 when it is discharged from the gap between the grinding disc shield 29 and the grinding disc 25, generating turbulence and affecting the overall efficiency of the airflow. Please refer to FIG. 11 , in one embodiment, the grinding disc shield 29 is observed from the interface 292 toward the release port 293, and the inner wall of the release port 293 has a drainage section 294, an arc-shaped turning section 295, and an air outlet section 296 in sequence. The drainage section 294 is seamlessly connected to the inner wall surface of the shield body 291 near the release port 293, and the drainage section 294 and the inner wall surface of the shield body 291 near the release port 293 together form a flat surface. The arc-shaped turning section 295 serves as a connector between the drainage section 294 and the air outlet section 296, and the air outlet section 296 has a different slope from the drainage section 294. Further, the angle between the air outlet section 296 and the drainage section 294 is greater than 90 degrees. Furthermore, the air outlet section 296 can be parallel to the side 251 of the grinding disc 25 facing the grinding disc mask 29. As mentioned above, when the airflow (as indicated by 50 in FIG. 12 ) passes through the release port 293, the wall surface of the release port 293 (i.e., the guide section 294, the arc-shaped turning section 295, and the air outlet section 296) will produce a wall adhesion effect (also known as the Coanda effect) to change the flow direction, and finally be discharged through the air outlet section 296. Accordingly, the guide design on the release port 293 prevents the airflow from being discharged toward the grinding disc 25, thereby avoiding the turbulence derived from directly hitting the grinding disc 25 and affecting the overall efficiency of the airflow.

Continuing from the previous embodiment, and referring to FIG. 10 and FIG. 11 , in one embodiment, the level of the release port 293 is equal to or lower than the level of the substrate 241 of the airflow generating member 24 in the grinding plate shield 29. In addition, the diameter of the release port 293 is larger than the diameter of the set interface 292, and the grinding plate shield 29 is trumpet-shaped, so that the airflow velocity entering the grinding plate shield 29 from the air outlet 214 is slowed down to avoid excessive airflow velocity and turbulence in the grinding plate shield 29. In one embodiment, the distance between the release port 293 and each of the blades 242 (as indicated by 44 in FIG. 10 ) is larger than the diameter of each of the blades 242. Furthermore, the shield body 291 has a slope 297 between the set of interfaces 292 and the release port 293, the slope 297 is connected to the guide section 294 of the release port 293, and the slope of the guide section 294 is the same as the slope of the slope 297. On the other hand, in one embodiment, the distance from the outer edge of the air outlet 214 to the center of the motor shield 212 (as indicated by 45 in FIG. 6 ) is smaller than the outer diameter of the airflow generating member 24.

The above is only a preferred embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the scope of the patent application of the present invention should still fall within the scope of the patent of the present invention.

20: Electric grinding machine tool 21: Housing 211: Hollow housing 212: Motor shield 213: Partition 214: Air outlet 215: First air inlet 216: Second air inlet 217: Housing 218: Ventilation gap 219: Side wall 220: Top surface 221: Air inlet part 222: Air outlet part 223: Grip part 224: Grip part 225: Head section 226: Neck section 228: Middle axis 229: Auxiliary partition 23: Electric motor 24: Airflow generating part 241: Base plate 242: Fan blade 25: Grinding disc 251: Surface 261: airflow 262: airflow 27: circuit board 28: eccentric block 281: first part 282: second part 29: grinding disc shield 291: shield body 292: assembly interface 293: release port 294: flow section 295: arc turning section 296: air outlet section 297: inclined plane 30: airflow temporary storage area 40: palm measurement point 41: finger grip measurement point 42: distance 43: distance 44: distance 50: airflow 60: electric grinding tool 61: grinding disc shield 611: vent 62: airflow generating part 63: tool housing 631: Air inlet 64: Electric motor 70: Electric grinding machine tool 71: Active dust suction structure 72: Grinding disc cover 721: Inlet 73: Air flow generating part 74: Machine tool housing 741: Air inlet 75: Electric motor

Figure 1, a schematic diagram of the implementation of the first embodiment of the conventional electric grinding machine tool. Figure 2, a schematic diagram of the airflow of the first embodiment of the conventional electric grinding machine tool. Figure 3, a schematic diagram of the implementation of the second embodiment of the conventional electric grinding machine tool. Figure 4, a schematic diagram of the structure of the first embodiment of the electric grinding machine tool of the present invention. Figure 5, a schematic diagram of the decomposed structure of the first embodiment of the electric grinding machine tool of the present invention. Figure 6, a schematic diagram of the top view of the local structure of the first embodiment of the electric grinding machine tool of the present invention. Figure 7, a schematic diagram of the cross-section of the structure of the first embodiment of the electric grinding machine tool of the present invention. Figure 8, a schematic diagram of the airflow intake of the first embodiment of the electric grinding machine tool of the present invention. Figure 9, a schematic diagram of the airflow of the first embodiment of the electric grinding machine tool of the present invention (I). Figure 10, a schematic diagram of the enlarged local structure of the first embodiment of the electric grinding machine tool of the present invention (I). Figure 11, an enlarged schematic diagram of the partial structure of an embodiment of the electric grinding machine tool of the present invention (II). Figure 12, a schematic diagram of the airflow of an embodiment of the electric grinding machine tool of the present invention (II).

212: Motor mask

213: Partition

214: Air outlet

215: First air intake

216: Second air intake

217: Shell parts

219: Side wall

220: Top

25: Grinding disc

251: Noodles

261: Airflow

262: Airflow

29: Grinding disc mask

291: Mask body

Claims (15)

An electric grinding machine tool comprises: an electric motor; an air flow generating element that rotates when the electric motor is started; and A housing, comprising a hollow housing, a motor shield disposed in the hollow housing and provided with the electric motor, two partitions disposed between a side wall of the motor shield and the hollow housing, at least one side of which faces the air outlet of the airflow generating member, at least one first air inlet formed on the hollow housing, and at least one second air inlet formed on the hollow housing and spaced from the first air inlet, the connection line of the two partitions distinguishes the motor shield into an air inlet portion and an air outlet portion connected to the air inlet portion, the air outlet is close to the air outlet portion, the first air inlet faces the air inlet portion of the motor shield, and when the airflow generating member is activated, the first air inlet generates a pressure difference at the air inlet portion of the hollow housing close to the motor shield to cause air to enter the second air inlet. An electric grinding tool as described in claim 1, wherein the motor cover includes a top surface connected to the side wall, and the two partitions are connected to the side wall and allow the airflow to pass through the top surface. An electric grinding tool as described in claim 1 or 2, wherein two auxiliary partitions cooperating with the two partitions are arranged in the hollow outer shell. An electric grinding machine tool as described in claim 1 or 2, wherein the electric grinding machine tool includes a circuit board disposed in the housing and electrically connected to the electric motor, the housing has a grip portion on which the electric motor is mounted, and a holding portion on which the circuit board is mounted and extends from the grip portion, the first air inlet is located in the grip portion, and the second air inlet is located in the holding portion and faces the circuit board. An electric grinding tool as described in claim 4, wherein the grip portion includes a head section and a neck section extending from the head section and close to the airflow generating member, and the first air inlet is close to the position where the neck section is connected to the grip portion. An electric grinding tool as described in claim 4, wherein an air inlet position of the second air inlet is lower than an air inlet position of the first air inlet. An electric grinding tool as described in claim 1, wherein the housing is composed of a plurality of shell parts, one of which forms the motor cover, the two partitions, the air outlet, the first air inlet and the second air inlet. An electric grinding tool as described in claim 1 or 7, wherein the air outlet is arranged along the edge of the motor cover. A housing of an electric grinding tool comprises: a hollow outer shell; a motor shield located in the hollow outer shell; two partitions located between the side wall of the motor shield and the hollow outer shell, the two partitions being located on two opposite sides of the motor shield; at least one air outlet formed on one of the hollow outer shell and the outer edge of the motor shield; at least one first air inlet formed on the hollow outer shell, the first air inlet and the air outlet being located on both sides of the two partitions respectively, the first air inlet facing the motor shield and close to one of the two partitions; and At least one second air inlet is formed on the hollow outer shell and is located on the same side of the two partitions as the first air inlet. The distance from the second air inlet to the air outlet is greater than the distance from the first air inlet to the air outlet. The shell of the electric grinding tool machine as described in claim 9, wherein two auxiliary partitions cooperating with the two partitions are arranged in the hollow outer shell. The shell of the electric grinding tool machine as described in claim 10, wherein the hollow outer shell is divided into a grasping portion and a holding portion extending from the grasping portion, the first air inlet is located in the grasping portion, and the second air inlet is located in the holding portion. The housing of an electric grinding tool machine as described in claim 10, wherein the grip portion includes a head section and a neck section extending from the head section, and the first air inlet is close to the position where the neck section is connected to the grip portion. A housing for an electric grinding tool machine as described in claim 12, wherein an air inlet position of the second air inlet is lower than an air inlet position of the first air inlet. The shell of an electric grinding tool machine as described in claim 9, wherein the hollow shell is formed by a plurality of shell parts, one of which forms a part of the hollow shell, the motor cover, the two partitions, the air outlet, the first air inlet and the second air inlet. The housing of the electric grinding tool as described in claim 9, wherein the air outlet is arranged along the edge of the motor cover.

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