Small motor

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to cooling a small motor, for example, a small motor used for an electric tool such as a drill.

【0002】

[Conventional technology]

Small motors used for electric tools such as drills generate heat from the sliding surface of the commutator 12 in contact with the brush due to its contact resistance and friction. It was provided.

【0003】

FIG. 13 is a vertical cross-sectional view of a main part of a small motor having a built-in cooling fan of the prior art (hereinafter referred to as the prior art 1). In FIG. 13, reference numeral 1 denotes a housing, which is formed of a metal material in the shape of a hollow cylinder with a bottom, and a permanent magnet 3 formed in the shape of an arc segment is fixed to the inner peripheral surface. The housing 1 is configured to face the permanent magnet 3 and support a rotor 8 composed of an armature iron core 9 and a commutator 12 wound with a coil 10. Reference numeral 14 denotes a brush, which is formed of a conductive elastic material and is provided on the end plate 4 so as to be slidably engaged with the commutator 12 and together with an input terminal which is electrically connected to the brush. Reference numeral 11 denotes a bearing, which is fixed to the bottom of the housing 1 and the central portion of the end plate 4 to rotatably support the rotor 8. 5, 6 and 7 are air holes, respectively, and are provided at appropriate positions on the housing 1 and the end plate 4. Reference numeral 13 denotes a cooling fan, which is provided between the armature core 9 of the rotor 8 and the commutator 12, and is formed to be rotatable integrally with the rotor 8.

【0004】

14 to 16 are a front view, a right side view, and a right side view of only the cooling fan 13 showing the rotor 8 of the 3-pole small motor equipped with the cooling fan 13 of the prior art 1, respectively. The rotor 8 is composed of an armature core 9, a coil 10, a commutator 12, a cooling fan 13, and a shaft 15 coupled to an external device. The cooling fan is formed by integrally connecting a plurality of fins 34 between the fixing fan ring 38 and the positioning fan ring 39 provided at intervals in the axial direction.

【0005】

When assembling the cooling fan 13 to the rotor 8, a commutator 12 is provided on the inner peripheral surfaces of the fan ring 38 for fixing the cooling fan 13, and in these figures, the inner peripheral surfaces of the five protrusions 37 are each provided. It abuts on the outer peripheral surface of the rotor 8 and is fixed to the rotor 8 by supplying an adhesive to the inside of the fixing fan ring 38. At this time, a plurality of bosses 36 provided on the end faces of the positioning fan ring 39 are for axial positioning, and may be inserted into the slots provided in the armature core 9 or the armature core 9 may be inserted. It is brought into contact with the end face.

【0006】

As shown in FIG. 13, when the rotor 8 having such a configuration is housed in the housing 1 and rotates, the air sucked from the housing air hole 5 by the cooling fan 13 that rotates integrally is generated in FIG. It passes over the commutator 12 from right to left, cools it, and is expelled from the fins 34 radially outward through the air holes 6 in the housing.

【0007】

However, in the cooling fan 13 of the prior art 1, the space between the fixing fan ring 38 and the commutator 12 is blocked by the positioning protrusion 37 and the adhesive, which makes it difficult for the air flow on the side surface of the commutator to flow, and the commutator slides. There is a drawback that the cooling effect of the surface is reduced. Further, the sliding surface 12 of the commutator in contact with the brush generates heat due to its contact resistance and friction, but in order to fix the cooling fan to the commutator that generates heat, a material having high heat resistance is used. It had the disadvantage of being necessary and costly.

【0008】

Therefore, conventionally, it has been considered that the commutator is not used for fixing and positioning the cooling fan, and only the end face of the armature core is used. Examples of such a cooling fan of the prior art (hereinafter referred to as the prior art 2) are shown in FIGS. 17 and 18. FIG. 18 is a side view of the cooling fan 13, and FIG. 17 is a cross-sectional view cut by the XX.

【0009】

In the cooling fan 13, the annular blade support 25 and the fan blade 26 are integrally supported on the cylindrical wall 27, and the tab 28 integrally provided on the cylindrical wall 27 is inserted between the armature cores and adhered. Is fixed to the rotor.

【0010】

However, although the cooling fan having such a configuration has the effect of not requiring a highly heat-resistant material, the cooling effect is shown in FIGS. 14 to 16 as will be described later with reference to FIG. It should not be better than the prior art 1. This is because the fan blade cannot be stably supported in such a configuration, and therefore the surface area of the fan blade cannot be increased.

【0011】

[Problems to be Solved by the Invention]

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, improve the configuration of the cooling fan, form a stable air flow, increase the air volume with less power, and wind near the commutator. Is to increase the cooling effect of the commutator.

【0012】

Further, an object of the present invention is to provide a low-cost compact motor that can be used even with a material having low heat resistance while improving the mounting configuration of the cooling fan to stably support the cooling fan.

【0013】

[Means for solving problems]

In FIG. 1, which is a vertical cross-sectional view of a main part of a 5-pole rotor small motor incorporating a cooling fan of the present invention, reference numeral 1 denotes a housing, which is formed of a metal material into a bottomed hollow cylinder and is permanently formed on the inner peripheral surface. Fix the magnet 3. The housing 1 is configured to face the permanent magnet 3 and support a rotor 8 composed of an armature iron core 9 and a commutator 12 wound with a coil 10. The rotor 8 is composed of an armature core 9, a coil 10, a commutator 12, a cooling fan 13, and a shaft 15 coupled to an external device. Reference numeral 14 denotes a brush, which is made of a conductive elastic material and is provided so as to be slidably engaged with the commutator 12. 5, 6 and 7 are air holes, respectively, and are provided at appropriate positions on the housing 1 and the end plate 4. Reference numeral 13 denotes a cooling fan, which is positioned and fixed to the end face of the armature core 9 of the rotor 8 and is rotatably formed integrally with the rotor 8.

【0014】

As seen in FIGS. 2 to 4, the cooling fan has a plurality of fins 34 integrally connected between the first fan ring 32 and the second fan ring 33 provided at intervals in the axial direction. It is formed. As can be seen in FIG. 2, a gap through which air flows is provided between the inner diameter of the first fan ring 32 and the circumferential surface of the commutator 12. Then, such a cooling fan 13 is positioned by two adjacent pairs of bosses 31 and 31 provided on the end face of the second fan ring 33, and the second fan ring is an armature iron core by an adhesive. It is glued to the end face of 9.

【0015】

As can be seen in FIG. 6, the boss 31 of the cooling fan 13 is provided along the angle of the blade portion 17 of the core, and when this is inserted into the gap of the winding portion of the armature core, the core blade portion 17 is provided. It is provided so as to be in contact with the insulated inner peripheral surface of the. The groove 30 between the two adjacent pairs of bosses 31 is provided slightly deeper than the end face of the second fan ring 33 in contact with the end face of the armature core, as shown as a in FIG. Has been done.

【0016】

The second fan ring 33 of the cooling fan 13 is fixed to the end face of the protruding armature core 9 with an adhesive. At this time, in order to further increase the fixing force, a step for the purpose of an adhesive pool is used. Is provided. This is shown as groove 29 in FIGS. 3 and 5. Further, an appropriate number of protrusions 40 are provided between the bosses 31 as shown in FIGS. 20 to 21, for example, on the surface of the second fan ring 33 to be adhered to the end surface of the armature core 9. In particular, when a high-viscosity adhesive is used, a space for attaching the adhesive is secured.

【0017】

Further, as seen in FIG. 4 or 5, the fin 34 of the cooling fan 13 of the present invention has an angle from the middle of the fin toward the tip, and the thickness of the fin is reduced on the tip side.

【0018】

BEST MODE FOR CARRYING OUT THE INVENTION

1 to 5 are the first embodiments in which the present invention is applied to a small motor having a 5-pole rotor, and FIG. 1 shows a main part of such a small motor incorporating the cooling fan of the present invention. It is a vertical sectional view.

【0019】

In FIG. 1, reference numeral 1 denotes a housing, which is formed of a metal material such as soft iron in the shape of a bottomed hollow cylinder, and a permanent magnet 3 formed in the shape of an arc segment is fixed to the inner peripheral surface, and an opening thereof is formed. The end plate 4 is fitted to the housing. The housing 1 is configured to face the permanent magnet 3 and support a rotor 8 composed of an armature iron core 9 and a commutator 12 wound with a coil 10. The rotor 8 is composed of an armature core 9, a coil 10, a commutator 12, a cooling fan 13, and a shaft 15 coupled to an external device. Reference numeral 14 denotes a brush, which is formed of a conductive elastic material and is provided on the end plate 4 so as to be slidably engaged with the commutator 12 and together with an input terminal which is electrically connected to the brush. Reference numeral 11 denotes a bearing, which is fixed to the bottom of the housing 1 and the central portion of the end plate 4 to rotatably support the rotor 8. 5, 6 and 7 are air holes, respectively, and are provided at appropriate positions on the housing 1 and the end plate 4. Reference numeral 13 denotes a cooling fan, which will be described in detail later. It is positioned and fixed to the end face of the armature core 9 of the rotor 8 and is rotatably formed integrally with the rotor 8.

【0020】

When the rotor 8 having such a configuration rotates, the air sucked from the housing air hole 5 by the integrally coupled cooling fan 13 passes over the commutator 12 from right to left in FIG. Is discharged from the fins of the cooling fan 13 radially outward through the air hole 6 of the housing.

【0021】

FIG. 2 is a right side view showing the 5-pole rotor 8 of FIG. 1, and FIGS. 3 and 4 are a front view and a right side view of the cooling fan 13. The cooling fan is formed by integrally connecting a plurality of fins 34 between the first fan ring 32 and the second fan ring 33 provided at intervals in the axial direction. As can be seen in FIG. 2, a gap through which air flows is provided between the inner diameter of the first fan ring 32 and the outer peripheral surface of the commutator 12. Then, such a cooling fan 13 is positioned with respect to the armature core by two adjacent pairs of bosses 31 and 31 provided on the end face of the second fan ring 33, and is second by an adhesive. The fan ring is glued to the end face of the armature core 9.

【0022】

As the cooling fan 13 rotates, the air that cools the commutator 12 passes through the gap between the commutator 12 and the first fan ring, and the first and second, especially as seen in FIG. It will be discharged through the openings 35 formed by the fan rings 32, 33 and each fin 4. In the cooling fan 13 of the present invention, the fins 34 are reliably and stably supported by the first and second fan rings 32 and 33, and the cooling fan 13 itself is reliably and stably on the end face of the armature core as described later. Therefore, the area of the opening 35 serving as the air passage and the surface area of the fins 34 can be increased, thereby enhancing the cooling effect.

【0023】

FIG. 6 is a detailed view showing an enlarged portion A cut along the line II shown in FIG. In FIG. 6, 10 is a coil, 16 is a core constituting an armature core, 17 is a core blade, 18 is an insulating coating of core 16, 19 is a winding gap, and 31 is a pair of positioning bosses. 30 is the groove between the two paired bosses.

【0024】

As can be seen in FIG. 6, the boss 31 of the cooling fan 13 is provided along the angle of the blade portion 17 of the core, and when this is inserted into the gap of the winding portion of the armature core, the core blade portion 17 is provided. It is provided so as to be in contact with the insulated inner peripheral surface of the. The groove 30 between the two adjacent pairs of bosses 31 is provided slightly deeper than the end face of the second fan ring 33 in contact with the end face of the armature core, as shown as a in FIG. Has been done. Therefore, the boss 31 can easily bend inward (in the direction indicated by the arrow in FIG. 6).

【0025】

The side of the armature core 9 facing the winding part is coated with a coating 18 for insulation, and this coating method is also usually performed by spraying a powdered material to cure it. The thickness of the film is not constant, and even one armature core is not constant depending on the location. The boss 31 comes into contact with the inner peripheral surface of the core blade portion having this inconsistent dimension, but as described above, the groove 30 is formed deeper than the end surface of the second fan ring 33, and the boss 31 is easily bent inward. Therefore, it is possible to absorb the variation in the thickness of the insulating coating layer and cope with it.

【0026】

Further, the boss 31 has a boss tip thicker than the boss root on the ring side. To illustrate this, see FIGS. 7 and 8 showing cross sections along lines II-II of FIG. As described above, when the boss 31 is inserted into the gap of the armature core winding portion, it bends inward according to the variation in the thickness of the insulating coating layer. At that time, as shown in FIG. In addition, if the base of the boss is not thinned, the side surface of the boss 31 will not be parallel to the armature core, in other words, the boss 31 will contact the armature core at the base of the boss instead of the entire surface. Become. In this case, the elastic force of the boss acts to move the cooling fan away from the armature core, that is, to raise it. In the present invention, in order to prevent this, as shown in FIG. 8, the root portion of the side surface of the boss is thinned so that the root portion does not come into contact with the insulating coating but comes into contact with the tip portion thereof. As a result, it is possible to suppress the force to pull out when the boss bends inward and prevent the cooling fan from rising. The cooling fan 13 positioned on the end face of the armature core 9 using such a boss 31 has its second fan ring 33 fixed to the end face of the armature core 9 with an adhesive. At this time, in order to further increase the fixing force, a step is provided for the purpose of adhering. This is shown as groove 29 in FIGS. 3 and 5. Further, on the surface of the second fan ring 33 to be adhered to the end surface of the armature iron core 9, an appropriate number of protrusions 40 are formed between the bosses 31, for example, as shown in FIGS. 20 to 21 in pairs. It is provided on both sides of the boss pair 31 to secure a space for attaching the adhesive, especially when a high-viscosity adhesive is used. In FIGS. 22 and 23, when a high-viscosity adhesive, for example, an adhesive having a viscosity of about 0.6 to 0.7 mm is used and attached to the end face of the armature core with a width of 1 mm, the height of the protrusion is 0.5. A good adhesive effect can be obtained by setting the thickness to about mm. As described above, since the cooling fan is adhered to the end face of the armature core instead of the commutator that generates heat, it is not necessary to use a material having high heat resistance, and therefore, it can be manufactured at low cost. .. As the cooling fan material, for example, 66 nylon (PA66) polyamide can be used, and as the adhesive, for example, an epoxy-based, urethane-based, or ester-based adhesive can be used. When using a low-viscosity adhesive, the step shown as the groove 29 in FIG. 3 or 5 corresponds to it, and when using a high-viscosity adhesive, a protrusion 40 as shown in FIGS. 20 to 21 is provided. It can be dealt with by.

【0027】

Further, as seen in FIG. 4 or 5, the fin 34 of the cooling fan 13 of the present invention is provided with an angle from the middle of the fin toward the tip, and the thickness of the fin is reduced on the tip side. This directs the wind radially outward, regardless of the direction of rotation of the motor and therefore the cooling fan.

【0028】

The air from the fins 34 is perpendicular to the surface of the fins 34 in order to allow more air to escape through the air holes 6 drilled in the housing 1 on the radial outside of the fins 34 of the cooling fan 13 and to improve the cooling effect. It is desirable to point outward as much as possible from the fin 34, not in the direction. However, in the case of a motor that needs to be reversed forward and reverse, this cannot be achieved by making the shape of the cooling fin 34, for example, a dogleg shape or an arc shape.

【0029】

In the present invention, by configuring the fin shape of the cooling fan as described above, the wind can be directed outward in the radial direction regardless of whether the fan is rotated in the forward or reverse direction, and therefore the cooling effect can be improved. it can.

【0030】

9 to 12 are the second embodiments in which the present invention is applied to a small motor having a 3-pole rotor. 9 and 10 are front views and right side views showing a three-pole rotor, and FIGS. 11 and 12 are front views and right side views of the cooling fan 13.

【0031】

This second embodiment is the same as the first embodiment except that the rotor has three poles. The configuration of the cooling fan 13 is also different from the first embodiment of 5 pairs in that the number of positioning bosses 31 is 3 pairs, as seen in FIG. 12, but it is basic. Is the same as in the first embodiment.

【0032】

FIG. 19 shows the experimental results of measuring the case surface temperature for the prior art 1, the prior art 2, and the present invention. The horizontal axis represents the passage of measurement time, and the vertical axis represents the change in temperature measured on the surface of the case. Regarding the prior art 1 and the present invention, the standard case and the one with an additional air hole were measured, respectively. In both cases, the present invention has a lower temperature rise and an excellent cooling effect than the prior art. You can see that there is. According to this measurement result, the prior art 2 is the worst in terms of the cooling effect, although it has the effect that the cooling fan does not need to be fixed on the commutator surface having a high temperature as described above.

【0033】

FIG. 20 is a left side view and a front view of the 5-pole cooling fan. In this figure, a configuration is shown in which protrusions 40 are provided on both sides of each boss pair 31 on the surface of the second fan ring 33 to be adhered to the end face of the armature iron core, and the second fan ring is provided by the protrusions 40. It is possible to secure a space for attaching the adhesive between the 33 and the end face of the iron core 9. The height of the protrusion 40 is preferably about 0.4 to 0.6 mm, although it depends on the viscosity of the adhesive. FIG. 21 shows the case where it is applied to a cooling fan for 3 poles.

【0034】

FIG. 22 shows a configuration in which the cooling fan 13 shown in FIG. 20 is attached to the armature core 9. Protrusions 40 are provided on both sides of the boss pair 31, in other words, two protrusions 40 are provided between the boss pairs 31. An adhesive 41 can be attached between the protrusions to attach a cooling fan. Since the axial height of the protrusion 40 is set to 0.4 to 0.6 mm, the part surrounded by the end faces of the protrusion 40, the second fan ring 33, and the armature core 9 becomes an "adhesive pool", and the second 2 The fixing force can be increased compared to the case where the fan ring and the end face of the armature core are directly bonded.

【0035】

[Effect of the invention]

In the cooling fan of the present invention, the fins are reliably and stably supported by the first and second fan rings, and the cooling fan itself is securely and stably attached to the end face of the armature core, so that the opening serves as a wind passage. It is possible to increase the area of the fan and the surface area of the fins, thereby enhancing the cooling effect. As described above, since the cooling fan is adhered to the end face of the armature core instead of the commutator that generates heat, it is not necessary to use a material having high heat resistance, and therefore, it can be manufactured at low cost. ..

【0036】

The boss provided on the second fan ring comes into contact with the insulating coating layer on the inner peripheral surface of the core blade whose dimensions of the armature core are not constant, but forms a groove deeper than the end surface of the second fan ring. Since the boss is configured to bend inward easily, it is possible to absorb the variation in the thickness of the insulating coating layer and cope with it. In addition, the base of the boss is made thinner so that it does not come into contact with the insulating coating at the base, but at the tip of the boss, which suppresses the force that the boss tries to pull out when it bends inward, and the cooling fan It is possible to prevent lifting.

【0037】

The second fan ring of the cooling fan is fixed to the end face of the armature core using an adhesive. At this time, a step for the purpose of collecting the adhesive or a space for attaching the adhesive by a protrusion is provided. Therefore, the adhesive force can be further increased.

【0038】

Further, the fins of the cooling fan of the present invention are angled from the middle of the fin toward the tip, so that the wind is directed outward in the radial direction regardless of the rotation direction of the motor and therefore the cooling fan. The cooling effect can be improved.

[Simple explanation of drawings]

[Figure 1]

It is a vertical sectional view of a main part of a small motor of a 5-pole rotor with a built-in cooling fan of the first embodiment.

[Figure 2]

It is a right side view which shows the 5 pole rotor in 1st Embodiment.

[Fig. 3]

It is a front view of the cooling fan in 1st Embodiment.

[Fig. 4]

It is a right side view of the cooling fan in 1st Embodiment.

[Fig. 5]

It is a left side view of the cooling fan in 1st Embodiment.

[Fig. 6]

It is sectional drawing of the part A of FIG.

[Fig. 7]

It is a cross-sectional detailed view along the line II-II of FIG. 6 when the boss root is not thinned.

[Fig. 8]

It is a cross-sectional detailed view along the line II-II of FIG. 6 when the boss root portion is thinned.

[Fig. 9]

It is a front view of the 3-pole rotor to which the cooling fan of the 2nd Embodiment is attached.

[Fig. 10]

It is a right side view of the 3-pole rotor to which the cooling fan of the 2nd Embodiment is attached.

[Fig. 11]

It is a front view of the cooling fan in 2nd Embodiment.

[Fig. 12]

It is a left side view of the cooling fan in the 2nd Embodiment.

[Fig. 13]

It is a vertical cross-sectional view of a main part of a small motor with a built-in cooling fan of the prior art 1.

[Fig. 14]

It is a front view which shows the rotor of the prior art 1.

[Fig. 15]

It is a right side view which shows the rotor of the prior art 1.

[Fig. 16]

It is a right side view of only the cooling fan of the prior art 1.

[Fig. 17]

It is sectional drawing of the cooling fan of the prior art 2.

[Fig. 18]

It is a side view of the cooling fan of the prior art 2.

[Fig. 19]

The experimental results of measuring the case surface temperature for the prior art 1, the prior art 2, and the present invention are shown.

[Fig. 20]

It is a left side view and the front view of the 5-pole cooling fan provided with a protrusion.

[Fig. 21]

It is a left side view of the cooling fan for 3 poles equipped with a protrusion.

[Fig. 22]

It is a front view of the rotor which attached the cooling fan which provided the protrusion.

[Fig. 23]

It is a cross-sectional view of III-III of FIG. 23, and is an enlarged view of the bonding portion between the second fan ring and the core.

[Explanation of symbols]

1 housing 3 Permanent magnet 4 end plate 5 ~ 7 wind holes 8 rotor 9 Armature iron core 10 coils 11 Bearings 12 commutator 13 Cooling fan 14 brush 15 shaft 16 cores 17 Core blade 18 Insulation coating 19 Winding gap 29 Ring groove 30 Groove between bosses 31 Positioning boss 32 1st fan ring 33 2nd fan ring 34 fins 35 openings 40 protrusions 41 Adhesive