TWI823670B - Electric grinding tool machine and its grinding disc cover - Google Patents

Abstract

An electric grinding machine tool and its grinding disk cover are provided. The electric grinding machine tool includes a holding body, an electric motor, a grinding disk, and an air flow generating member. When the electric motor rotates, the air flow generating member forms a cooling air flow in the holding body. The grinding disc cover is assembled with the holding body and covers the air flow generating member therein. The grinding disc cover includes a The cover body, a set of interfaces, and a release port facing the grinding disc. The cover body does not have a vent other than the set of interfaces and the release port. The release port is viewed from the direction of the set of interfaces to the release port. The inner wall of the release port has a drainage section, an air outlet section with a slope different from that of the drainage section, and an arc-shaped turning section connecting the drainage section and the air outlet section.

Description

Electric grinding tool machine and its grinding disc cover

The present invention relates to an electric grinding machine tool, and in particular to an electric grinding machine tool using a grinding disk cover that can guide the direction of air outflow and without lateral ventilation holes.

Existing electric grinding tools generally have an air flow generating member attached to an eccentric block so as to generate cooling airflow through the air flow generating member and discharge the waste heat generated during operation of the electric grinding machine tool. One of the implementations is as disclosed in EP2132000B1, or as shown in Figure 1 . In the technical solution disclosed in FIG. 1 , a grinding disc cover 61 of the electric grinding tool machine 60 is provided with a plurality of vent holes 611 arranged at intervals in the side direction. The air flow generating member 62 is disposed close to the vent holes 611 , and at the same time Close to the port where the grinding disc cover 61 is connected to a holding body 63 . Ideally, when the air flow generating member 62 rotates, the air flow generating member 62 will introduce air from the vent holes 611 to dissipate heat. However, the vent holes 611 are spaced apart and the air flow generating member 62 is too close to the vent holes 611. Because of this, in fact, the vent holes 611 cannot produce the expected effect. When one of the vent holes 611 is for air intake, the other one that follows the vent hole 611 will produce exhaust. It can be said that A short flow problem (also called a short circulation) occurs, as shown in Figure 2 , causing the air intake efficiency of the vents 611 to not meet expectations. The short flow problem causes the heat dissipation effect of the air flow generating member 62 to be limited to an eccentric Although the eccentric block can dissipate waste heat because it is connected to an electric motor 64, the shaft diameter of the shaft connecting the eccentric block to the electric motor 64 is generally small, and the waste heat transfer speed is not as fast as that generated by the electric motor 64 itself. Heat, causing waste heat to accumulate continuously and affecting the user's feeling when holding it.

Furthermore, although some embodiments have a plurality of air inlet holes 631 on the holding body 63, and the rotation of the air flow generating member 62 attracts external air to enter through the air inlet holes 631 to form a cooling air flow, but as mentioned above, It can be seen that the air flow generating member 62 has a problem of poor air intake efficiency and cannot generate the required suction force, so that the cooling air flow volume is insufficient to effectively dissipate the heat of the electric motor 64 , and the waste heat accumulation of the electric motor 64 is still serious. In addition, the starting point of the aforementioned design is to enhance the heat exchange with the electric motor 64 through large air volume. However, the existing implementation does not carry out a fluid design for the grinding disc cover 61 and is only given the function of shielding a grinding disc 65 . The existing inner wall of the grinding plate cover 61 is a bevel, and the end of the bevel faces the grinding plate 65. The above design will cause the aforementioned heat dissipation airflow to be directed to the grinding plate 65 when it is exhausted, and will hit the grinding plate 65, causing the grinding plate to Turbulent flow is generated in the shield 61, which will affect the exhaust air and prevent the originally expected large air flow from being realized.

Currently, the only solution that can solve the aforementioned problems is to implement an electric grinding machine tool 70 with an active dust suction structure 71, as shown in Figure 3 or EP2946710B1. Referring to Figure 3 to illustrate, the air inlet of the active dust suction structure 71 is a suction inlet 721 opened on a grinding disc cover 72. During implementation, the active dust suction structure 71 will be connected to the grinding disc cover 72. The inner space generates a suction force, which is significantly greater than the suction force generated by an air flow generating member 73, and a plurality of air inlet holes 741 on the holding body 74 sucks in a large amount of gas. The large amount of gas sucked in from these air inlet holes 741 is harmful to an electric motor. The heat dissipation of 75 helps a lot.

However, not all electric grinding tools can be equipped with the active dust suction structure, and it is still necessary to find a solution to the heat accumulation in the electric motor when the electric grinding tool is not equipped with the active dust suction structure.

The main purpose of the present invention is to solve the problem of the actual impact of the conventional grinding disc cover design on the heat dissipation air flow.

A secondary purpose of the present invention is to solve the problem of heat accumulation in the electric motor of a conventional electric grinding machine tool that is difficult to discharge.

To achieve the above object, the present invention provides an electric grinding tool machine, which includes a holding body, an electric motor, an eccentric block, a grinding disc, an air flow generating member, and a grinding disc cover. The holding body is formed with at least one air inlet, the electric motor is located in the holding body, the eccentric block is connected to the electric motor and rotates with the electric motor, the grinding disc is assembled with the eccentric block, and the air flow generating member Attached to the eccentric block, the air flow generating member generates a cooling air flow in the holding body when the electric motor rotates. The grinding plate cover is assembled with the holding body and covers the air flow generating member therein. The grinding plate cover includes a covering body, an assembly formed on one end of the covering body and assembled with the holding body. an interface, and a release port formed on the other end of the shield body and facing the grinding disc. The cover body does not have vents other than the set of interfaces and the release port. The release port is the only exhaust part of the grinding disc cover. When viewing the release port from the direction of the set of interfaces to the release port, the release port The inner wall of the mouth has a drainage section, an arc-shaped turning section, and an air outlet section with a slope different from that of the drainage section in sequence. The arc-shaped turning section allows the heat dissipation air flow to pass between the grinding disc cover and the grinding disc. An air flow direction when the air is discharged is parallel to the grinding disc.

In one embodiment, the air flow generating member has a base plate and a plurality of fan blades spaced on the base plate. The distance between the top edge of each fan blade and the holding body is greater than each longitudinal height of the fan blades. 50% of the distance between the outer edge of each fan blade and the grinding disc cover is greater than 50% of each radial width of the fan blades.

In one embodiment, the horizontal height of the release port is equal to or lower than the horizontal height of the substrate in the grinding disc cover.

In one embodiment, the distance between the release opening and each of the fan blades is greater than the diameter width of each of the fan blades.

In one embodiment, the mask body has an inclined surface between the set of interfaces and the release port, the inclined surface is connected to the drainage section of the release opening, and the slope of the drainage section is the same as the slope of the slope.

In addition to the above, the present invention further provides a grinding disc cover for an electric grinding tool machine, which includes a cover body, an assembly interface formed on one end of the cover body, and an assembly interface formed on the other end of the cover body and connected with the cover body. The release port of this set of interfaces is coaxially set. The caliber of the release port is larger than the caliber of the set of interfaces. Viewing the release port from the direction of the set of interfaces to the release port, the inner wall of the release port has a drainage section, an arc-shaped turning section, and a slope different from that of the set of interfaces. The air outlet section of the drainage section. Wherein, the mask body does not have any ventilation opening other than the set of interfaces and the release opening.

In one embodiment, the mask body has an inclined surface between the set of interfaces and the release port, the inclined surface is connected to the drainage section of the release opening, and the slope of the drainage section is the same as the slope of the slope.

In one embodiment, the mask body has a connecting ring formed around the set of interfaces, and a continuous concave and convex structure is formed on the inside of the connecting ring.

According to the foregoing description of the invention, compared with the conventional technology, the present invention has the following characteristics: the grinding disc cover of the present invention uses the inner wall of the release port to produce a Coanda effect, so that the heat dissipation airflow is discharged not toward the grinding disc. Turbulence must be avoided to allow the cooling air flow to flow smoothly. Furthermore, since the heat dissipation air flow is discharged smoothly, the heat dissipation air flow generated in the electric grinding tool machine is enhanced, thereby solving the existing problem that the electric motor of the electric grinding tool machine is difficult to dissipate heat.

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

Referring to Figures 4 to 8, the present invention provides an electric grinding tool machine 20, which includes a holding body 21, an electric motor 22, an eccentric block 23, a grinding disc 24, an air flow generating member 25 and a grinding disc cover. Hood 26. Among them, the holding body 21 can be completed by splicing a plurality of housings 211. In addition to providing the electric motor 22, the internal space of the holding body 21 also provides a control circuit board 27 for controlling the operation of the electric motor 22. . One of the housings 211 is formed with a motor cover 212 that can cover the electric motor 22 therein. In addition, the holding body 21 is provided with a plurality of air inlet holes 213. The air inlet holes 213 can be respectively opened in the portion of the surface of the holding body 21 corresponding to the control circuit board 27, and the surface of the holding body 21 provides A part gripped by the user's fingers. In one embodiment, the holding body 21 has at least one air hole 214 connecting the inside of the holding body 21 and the grinding disc cover 26. The air hole 214 is provided in the housings 211 and is formed with the motor cover. On one of the covers 212 , the air hole 214 can be provided along the edge of the motor cover 212 . Further, the air hole 214 may be in an arc shape.

In addition, the electric motor 22 can be an internally rotating structure or an externally rotating structure. The eccentric block 23 is connected to a rotor 221 of the electric motor 22 and rotates with the rotor 221 . In one embodiment, the eccentric block 23 includes a first part 231 connected to the electric motor 22 , and a second part 232 connected to the first part 231 and whose center is offset from the center of the first part 231 . The grinding disc 24 is assembled on the eccentric block 23 , and an exhaust area 28 is defined between the grinding disc 24 and the edge of the grinding disc cover 26 .

Continuing with the above, please refer to FIG. 5 again. The air flow generating member 25 is attached to the eccentric block 23 and is located in the space defined by the grinding disc cover 26. The air flow generating member 25 moves together with the eccentric block 23. The air flow generating member 25 includes a base plate 251 and a plurality of fan blades 252 provided on the base plate 251. The fan blades 252 are of the same type. The fan blades 252 are only provided on the side of the base plate 251 facing the eccentric block 23. On the surface, the fan blades 252 are spaced apart and arranged in a circle on the base plate 251 . In order to smoothly introduce a large amount of gas into the holding body 21, the present invention is configured in the space defined by the grinding disc cover 26 based on the following conditions: the top edge of each fan blade 252 is in contact with the The distance between the holding bodies 21 (marked 30 in Figure 8) is greater than 50% of each longitudinal height of the fan blades 252, and the distance between the outer edge of each fan blade 252 and the grinding disc cover 26 The distance (marked 31 in FIG. 8 ) is greater than 50% of each radial width of the fan blades 252 , and the outer diameter of the airflow generating member 25 is greater than the distance from the air hole 214 to the center of the motor cover 212 . Based on the above conditions, the air flow generating member 25 is not close to the holding body 21 and the grinding disc cover 26, but can generate an air flow temporary storage area 29. The air flow temporary storage area 29 can make the air flow generating member 25 guide the air flow generating member 25. Wind effects remain smooth.

Please refer to Figures 5, 6 and 8 again. The grinding plate cover 26 is assembled with the holding body 21 and covers the airflow generating member 25 therein. The grinding disc cover 26 includes a cover body 261 , an assembly interface 262 formed on one end of the cover body 261 , and a release port 263 formed on the other end of the cover body 261 . According to the present invention, the grinding disc cover 26 does not have a vent other than the set of interfaces 262 and the release port 263. The set of interfaces 262 and the release port 263 are coaxially arranged, that is, the set of interfaces 262 and the release port 263 are arranged opposite to each other. Please refer to Figure 9. The release port 263 is the only exhaust part of the grinding plate cover 26. Use the set of interfaces 262 to observe the release port 263. The inner wall of the release port 263 has a A diversion section 264, an arc-shaped turning section 265, and an air outlet section 266. The drainage section 264 is connected to the inner wall surface of the shield body 261 close to the release opening 263 without any gap. The drainage section 264 and the inner wall surface of the shield body 261 close to the release opening 263 can jointly form a flat surface. The arc-shaped turning section 265 serves as a connector between the air outlet section 264 and the air outlet section 266. The air outlet section 266 and the air outlet section 264 have different slopes. Furthermore, the air outlet section 266 and the air outlet section 264 have different slopes. The angle between them is greater than 90 degrees. Furthermore, the air outlet section 266 can be parallel to the surface 241 of the grinding disc 24 facing the grinding disc cover 26 .

Please refer to Figures 10 to 12. When the air flow generating member 25 rotates, a cooling air flow 40 is generated in the electric grinding machine 20. The cooling air flow 40 enters the holding body 21 from the air inlet 213 and passes through the holding body 21. The motor cover 212 sequentially passes through the air holes 214 , the air flow temporary storage area 29 and the air flow generating member 25 , and is finally discharged from the exhaust area 28 . When the heat dissipation airflow 40 passes through the release port 263, a Coanda effect (also known as the Coanda effect) will be generated due to the wall surface of the release port 263 (ie, the drainage section 264, the arc-shaped turning section 265, and the air outlet section 266). Or Coanda Effect), the heat dissipation air flow 40 changes the flow direction under the action of the arc-shaped turning section 265, and is finally discharged from the exhaust area 28 along the air outlet section 266. Specifically, the arc-shaped turning section 265 causes an airflow direction 41 when the cooling airflow 40 exits from between the grinding plate cover 26 and the grinding plate 24 to be parallel to the grinding plate 24 . Accordingly, the present invention uses the guide design on the release port 263 to prevent the heat dissipation airflow 40 from being discharged toward the grinding plate 24, thereby preventing the heat dissipation airflow 40 from directly hitting the grinding plate 24 and causing turbulence in the exhaust area 28. flow, which affects the overall efficiency of the cooling air flow 40. That is to say, the present invention uses the Coanda effect generated by the release opening 263 to guide the heat dissipation air flow 40 to be discharged smoothly.

Based on the above, through the cooperation of the grinding disc cover 26 and the air flow generating member 25, the present invention can still generate the heat dissipation that meets the heat dissipation requirements of the electric motor 22 when the electric grinding tool machine 20 is not equipped with an active dust suction structure. The air flow 40 specifically improves the problem of heat accumulation in the electric motor 22 being difficult to discharge, and increases the comfort of the user's palm when holding and using it for a long time. Please also refer to Table 1 and Table 2. Table 1 shows the electric grinding tool machine of the present invention (referred to as the present invention in the table) and the conventional electric grinding machine tool machine that does not have an active dust collection structure and has a grinding disc cover with a ventilation hole (Table 1). Temperature rise comparison table of an electric grinding tool machine equipped with an active vacuum structure (represented in the table as conventionally used without vacuuming) and an electric grinding tool equipped with an active vacuum structure (represented in the table as conventionally used with vacuuming). The temperature measurement point is the position of the user's palm (marked 50 in Figure 4). The setting conditions are load 180W, sandpaper #80, and grinding disc 6 inches. The basic conditions of Table 2 are the same as Table 1, the only difference is that the temperature measurement point is the user's finger grip (marked 51 in Figure 4).

Table I ambient temperature Machine tool running time 10 minutes 15 minutes 20 minutes 25 minutes 30 minutes invention 22.3 28.8 30.9 31.7 31.8 31.7 Used without vacuuming 22.8 37.4 43.3 48.1 51.9 53.1 Used to vacuum 21.8 31.9 31.4 32.3 31.0 32.0

Table II ambient temperature Machine tool running time 10 minutes 15 minutes 20 minutes 25 minutes 30 minutes invention 22.3 24.8 25.2 24.9 24.4 24.3 Used without vacuuming 22.8 45.1 51.8 54.7 62.3 61.1 Used to vacuum 21.8 27.9 28.9 28.1 29.2 28.9

It can be clearly understood from Table 1 and Table 2 that after continuous operation of the conventional vacuum cleaner for 15 minutes, the temperature of the palm measurement point and finger grip measurement point increased significantly, while the palm measurement point and finger grip measurement point located on the surface of the machine tool Since the measuring point is already so high, it can be inferred that the temperature of the electric motor located inside the machine tool will be higher due to the accumulation of waste heat. This highlights that the heat dissipation air flow generated by the conventional design cannot effectively dissipate the heat accumulation of the electric motor. The grinding plate cover Design really affects the efficiency of this cooling air flow. Continuing, by comparing the temperatures of the present invention and conventional vacuum cleaners during the operation time of multiple machine tools, it can be found that when the structure of the present invention is not equipped with the active vacuum structure, the temperature of the palm measurement point and the finger grip measurement point are different. In addition to being comparable to the performance of regular vacuum cleaners, it also produces significantly better performance than regular vacuum cleaners in the finger grip measurement point (Table 2). Based on this, it can be said that the design of the release port 263 of the grinding plate cover 26 of the present invention really affects the efficiency of the heat dissipation air flow 40, and indeed makes the heat dissipation air flow 40 meet the heat dissipation needs of the electric motor 22, which cannot be solved by improving the conventional structure. Heat accumulation problem in electric motor.

Please refer to FIG. 8 again. In one embodiment, the horizontal height of the release opening 263 is equal to or lower than the horizontal height of the base plate 251 of the air flow generating member 25 in the grinding disc cover 26 to effectively guide the heat dissipation air flow. 40.

Please refer to Figures 5 to 8 again. The diameter of the release port 263 is larger than the diameter of the set of interfaces 262. The grinding plate cover 26 is in a trumpet shape to allow the heat dissipation airflow 40 to enter the grinding plate cover 26 from the air hole 214. The flow speed is slowed down to prevent the cooling air flow 40 from being too strong and causing turbulence in the grinding disc cover 26 . In one embodiment, the distance (marked 32 in the figure) between the release opening 263 and each of the fan blades 252 is greater than the diameter width of each of the fan blades 252 . In addition, the mask body 261 has an inclined surface 267 between the set of interfaces 262 and the release port 263. The inclined surface 267 is connected to the drainage section 264 of the release port 263, and the slope of the drainage section 264 is consistent with the inclined surface 267. The slopes are the same, and further, there is no step difference between the drainage section 264 and the slope 267 . Furthermore, the height of a top end 268 of the inclined surface 267 is equal to or higher than the horizontal height of each of the fan blades 252 . The positions of the top end 268 and the release opening 263 of the inclined surface 267 respectively face the top and bottom ends of each of the fan blades 252, thereby effectively guiding the air discharge from the air outlet end 253 of each of the fan blades 252. The cooling air flow is 40.

Referring again to FIGS. 6 and 8 , in one embodiment, the mask body 261 has a connecting ring 269 formed around the set of interfaces 262 , and a continuous concave-convex structure 260 is formed on the inside of the connecting ring 269 . On the other hand, the holding body 21 has a connecting concave-convex structure 215 assembled with the continuous concave-convex structure 260 at the location where the set of interfaces 262 is provided.

To sum up, the above is only a preferred embodiment of the present invention. It should not be used to limit the scope of the present invention. That is, all equivalent changes and modifications made according to the patent scope of the present invention should still belong to the present invention. patent coverage.

20: Electric grinding tool machine

21: Hold the body

211: Shell

212: Motor mask

213:Air intake hole

214: Air hole

215: Connect concave and convex structures

22: Electric motor

221:Rotor

23: Eccentric block

231:Part One

232:Part 2

24:Grinder disc

241: Noodles

25: Wind flow generating parts

251:Substrate

252:Fan blade

253:Outlet end

26: Grinding disc mask

261: Mask body

262:Group interface

263: Release port

264: Drainage section

265: Arc turning section

266: Air outlet section

267: Incline

268:Top

269:Connection ring

260: Continuous concave and convex structure

27:Control circuit board

28:Exhaust area

29: Fengliu temporary storage area

30:distance

31:distance

32:distance

40: Cooling air flow

41: Air flow direction

50: Palm measurement point

51: Finger grip measuring point

60: Electric grinding tool machine

61: Grinding disc mask

611:Vent hole

62:Wind flow generating parts

63: Hold the body

631:Air inlet

64: Electric motor

65:Grinder disc

70: Electric grinding tool machine

71: Active vacuum structure

72: Grinding disc mask

721:Suction port

73: Wind flow generating parts

74: Hold the body

741:Air inlet

75: Electric motor

Figure 1 is a schematic diagram of a conventional electric grinding machine tool (1). Figure 2 is a schematic diagram of the wind flow of a conventional grinding disc cover. Figure 3 is a schematic diagram (2) of the implementation of a conventional electric grinding machine tool. Figure 4 is a schematic view of the appearance of the electric grinding machine tool of the present invention. Figure 5 is an exploded schematic diagram of the structure of the electric grinding machine tool of the present invention. Figure 6 is a schematic cross-sectional view of the structure of the electric grinding tool machine of the present invention. Figure 7 is a schematic top view of the partial structure of the electric grinding tool of the present invention. Figure 8 is a schematic cross-sectional view of the partial structure of the electric grinding tool machine of the present invention (1). Figure 9 is a schematic cross-sectional view (2) of the partial structure of the electric grinding tool of the present invention. Figure 10 is a schematic diagram of the heat dissipation air flow path of the electric grinding tool machine of the present invention (1). Figure 11 is a schematic diagram (2) of the heat dissipation air flow path of the electric grinding tool machine of the present invention. Figure 12 is a schematic diagram (3) of the heat dissipation air flow path of the electric grinding tool machine of the present invention.

21: Hold the body

215: Connect concave and convex structures

25: Wind flow generating parts

251:Substrate

252:Fan blade

253:Outlet end

26: Grinding disc mask

261: Mask body

263: Release port

264: Drainage section

265: Arc turning section

266: Air outlet section

267: Incline

268:Top

269:Connection ring

260: Continuous concave and convex structure

29: Fengliu temporary storage area

30:distance

31:distance

32:distance

Claims (5)

An electric grinding tool machine, including: a holding body formed with at least one air inlet; an electric motor located in the holding body; an eccentric block connected to the electric motor and rotating with the electric motor; and a grinding disc , assembled with the eccentric block; an air flow generating member is attached to the eccentric block. When the electric motor rotates, the air flow generating member generates a cooling air flow in the holding body. The air flow generating member has a base plate and A plurality of fan blades are spaced on the base plate, the distance between the top edge of each of the fan blades and the holding body is greater than 50% of each longitudinal height of the fan blades; and a grinding disc cover is provided with the holding body. Hold the main body assembly and cover the air flow generating member therein. The distance between the grinding disc cover and the outer edge of each of the fan blades is greater than 50% of the radial width of each of the fan blades. The grinding disc The mask includes a mask body, an assembly interface formed on one end of the mask body and assembled with the holding body, and a release port formed on the other end of the mask body and facing the grinding disc. The mask body There is no ventilation port other than the set of interfaces and the release port. The release port is the only exhaust part of the grinding plate cover. When viewing the release port from the direction of the set of interfaces to the release port, the inner wall of the release port is It has a guide section, an arc-shaped turning section, and an air outlet section with a slope different from that of the guide section. The arc-shaped turning section allows the heat dissipation airflow to exit from between the grinding plate cover and the grinding plate. An airflow direction is parallel to the grinding disc. The electric grinding tool machine according to claim 1, wherein the horizontal height of the release port is equal to or lower than the horizontal height of the base plate in the grinding disc cover. The electric grinding machine tool according to claim 1 or 2, wherein the distance between the release port and each of the fan blades is greater than the diameter width of each of the fan blades. The electric grinding machine tool according to claim 3, wherein the shield body has an inclined surface between the set of interfaces and the release port, the inclined surface is connected to the drainage section of the release opening, and the slope of the drainage section is equal to The slope of this slope is the same. The electric grinding machine tool according to claim 4, wherein the height of the top of the inclined surface is equal to or higher than the horizontal height of each of the fan blades.

Images