JP3469751B2 - Small motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cooling a small motor, for example, a small motor used for an electric tool such as a drill.

[0002]

2. Description of the Related Art A small motor used for an electric tool such as a drill generates heat due to its contact resistance and friction from a sliding surface of a commutator 12 which is in contact with a brush. Conventionally, a cooling fan has been provided.

FIG. 13 is a vertical cross-sectional view of a main part of a small-sized motor (hereinafter referred to as prior art 1) having a conventional cooling fan built therein. In FIG. 13, reference numeral 1 denotes a housing, which is formed of a metal material in a hollow cylindrical shape with a bottom, and has an arc segment-shaped permanent magnet 3 fixed to the inner peripheral surface thereof. Inside the housing 1, the coil 1 faces the permanent magnet 3.
It is configured to support a rotor 8 including an armature core 9 wound with 0 and a commutator 12. Reference numeral 14 denotes a brush, which is made of a conductive elastic material and has a commutator 12
It is provided on the end plate 4 so as to be slidably engaged with the brush and an input terminal electrically connected to the brush. Reference numeral 11 denotes a bearing, which is fixed to the bottom portion of the housing 1 and the central portion of the end plate 4 and rotatably supports the rotor 8. Reference numerals 5, 6, and 7 are air holes, which are provided at appropriate positions of the housing 1 and the end plate 4.
A cooling fan 13 is provided between the armature core 9 of the rotor 8 and the commutator 12, and is formed so as to be rotatable integrally with the rotor 8.

14 to 16 are a front view, a right side view, and a right side view of only the cooling fan 13, respectively, showing a rotor 8 of a three-pole small-sized motor in which a cooling fan 13 of the prior art 1 is mounted. The rotor 8 includes an armature core 9, a coil 10,
It is composed of 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, which are provided at intervals in the axial direction.

When the cooling fan 13 is assembled to the rotor 8, the fan ring 38 for fixing the cooling fan 13 is attached.
The inner peripheral surface of each of the plurality of protrusions 37 provided on the inner peripheral surface of each of the five projections 37 in FIG. Is fixed to the rotor 8 by supplying. At this time, the plurality of bosses 36 provided on the end surface of the positioning fan ring 39 are for axial positioning, and are inserted into the slots provided in the armature core 9 or the bosses 36 of the armature core 9 are inserted. It is brought into contact with the end face.

When the rotor 8 having such a structure is housed in the housing 1 and is rotated as shown in FIG.
By the cooling fan 13 that rotates integrally, the air sucked from the housing air holes 5 passes over the commutator 12 from the right to the left in FIG.
4 is discharged radially outward through the air holes 6 in the housing.

However, the cooling fan 1 of the prior art 1
No. 3 has a drawback in that the space between the fixing fan ring 38 and the commutator 12 is blocked by the positioning projection 37 and the adhesive, the flow of air on the side surface of the commutator becomes difficult to flow, and the cooling effect on the sliding surface of the commutator is reduced. There is. Further, the sliding surface 12 of the commutator, which is in contact with the brush, generates heat due to the contact resistance and friction, but a material having high heat resistance is used to fix the cooling fan to the commutator that generates heat. There is a drawback that it is necessary and expensive.

Therefore, conventionally, it has been considered to use only the end face of the armature core without using the commutator for fixing and positioning the cooling fan. An example of such a conventional cooling fan (hereinafter referred to as the conventional technique 2) is shown in FIGS. 17 and 18. FIG. 18 is a side view of the cooling fan 13, and FIG. 17 is a sectional view taken along the line XX.

In the cooling fan 13, an annular blade support 25 and a fan blade 26 are integrally supported by a cylindrical wall 27, and the tab 2 integrally provided on the cylindrical wall 27.
8 is inserted between the armature cores and is fixed to the rotor by adhesion.

However, although the cooling fan having such a structure has an effect of not requiring a material having high heat resistance, as will be described later with reference to FIG. It is not good to compare with the prior art 1 shown in FIG. This is because the fan blade cannot be stably supported in such a configuration,
Therefore, the surface area of the fan blade cannot be increased.

[0011]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, improve the structure of the cooling fan, form a stable air flow, and use less power. This is to increase the amount of air flow and let the air flow near the commutator to enhance the cooling effect of the commutator.

A further object of the present invention is to provide a low-cost small-sized motor which can improve the mounting structure of the cooling fan to support it stably and use a material having low heat resistance.

[0013]

FIG. 1 is a longitudinal sectional view of a main part of a 5-pole rotor small motor incorporating a cooling fan according to the present invention. In FIG. 1, reference numeral 1 denotes a housing, which is a hollow cylinder having a bottom and made of a metal material. And the permanent magnet 3 is fixed to the inner peripheral surface. In this housing 1, facing the permanent magnet 3,
It is configured to support a rotor 8 including an armature core 9 formed by winding a coil 10 and a commutator 12. 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. Reference numerals 5, 6, and 7 are air holes, which are provided at appropriate positions of the housing 1 and the end plate 4. 13 is a cooling fan, and the armature core 9 of the rotor 8
It is positioned and fixed to the end surface of the rotor and is rotatably formed integrally with the rotor 8.

As shown in FIGS. 2 to 4, the cooling fan includes a plurality of fins 3 between a first fan ring 32 and a second fan ring 33 which are axially spaced from each other.
4 are integrally connected. Between the inner diameter of the first fan ring 32 and the circumferential surface of the commutator 12, as shown in FIG. 2, there is a gap through which air flows. The cooling fan 13 is positioned by the two adjacent bosses 31, 31 provided on the end surface of the second fan ring 33, and the second fan ring is attached by an adhesive to the armature core. It is adhered to the end face of 9.

As shown 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 the boss 31 is inserted into the gap of the winding portion of the armature core, It is provided so as to contact the insulated inner peripheral surface of the blade portion 17. This pair of two adjacent bosses 31
The groove 30 between them is provided slightly deeper than the end surface of the second fan ring 33 that is in contact with the end surface of the armature core, as indicated by a in FIG.

The second fan ring 33 of the cooling fan 13 is fixed to the end surface of the projecting armature core 9 with an adhesive. At this time, in order to increase the fixing force, the purpose is to collect the adhesive. There is a step. This is shown in Figure 3.
And in FIG. 5 as groove 29. Also,
An appropriate number of projections 40 are provided on the surface of the second fan ring 33 that is bonded to the end surface of the armature core 9 between the bosses 31, as shown in FIGS. When using a high-viscosity adhesive, a space for attaching the adhesive is secured.

Further, as shown in FIG. 4 or 5, the fins 34 of the cooling fan 13 of the present invention have an angle toward the tip from the middle of the fins, and the fins are thinned on the tip side. is there.

[0018]

1 to 5 show a first embodiment in which the present invention is applied to a small motor having a five-pole rotor, and FIG. 1 has such a cooling fan of the present invention built therein. FIG. 4 is a vertical cross-sectional view of a main part of the small motor thus made.

In FIG. 1, reference numeral 1 denotes a housing, which is formed of a metal material such as soft iron into a hollow cylindrical shape with a bottom, and a permanent magnet 3 formed in an arc segment shape is fixed to the inner peripheral surface of the housing. The end plate 4 is fitted in this opening. An armature core 9 is provided inside the housing 1 so as to face the permanent magnet 3 and a coil 10 is wound around the armature core 9.
And a commutator 12 to support the rotor 8. 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 electrically connected to the brush.
Reference numeral 11 denotes a bearing, which is fixed to the bottom portion of the housing 1 and the central portion of the end plate 4 and rotatably supports the rotor 8. Reference numerals 5, 6, and 7 are air holes, which are provided at appropriate positions of the housing 1 and the end plate 4. Reference numeral 13 denotes a cooling fan, which will be described in detail later, but is positioned and fixed to the end surface of the armature core 9 of the rotor 8 and is formed so as to be rotatable integrally with the rotor 8.

When the rotor 8 having such a structure rotates,
By the cooling fan 13 integrally connected, the air taken in from the housing air hole 5 passes over the commutator 12 from the right to the left in FIG. The air is discharged to the outside in the direction through the air holes 6 of the housing.

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 includes a first fan ring 32 and a second fan ring 33, which are provided at intervals in the axial direction.
Is formed by integrally connecting a plurality of fins 34 between. Between the inner diameter of the first fan ring 32 and the outer peripheral surface of the commutator 12, there is a gap through which air flows, as can be seen especially in FIG. The cooling fan 13 is positioned with respect to the armature core by two adjacent bosses 31, 31 provided on the end surface of the second fan ring 33, and the cooling fan 13 is secondly bonded by an adhesive. The fan ring is bonded to the end surface of the armature core 9.

When the cooling fan 13 rotates, the commutator 1
The air that has cooled the 2 passes through the gap between the commutator 12 and the first fan ring and by the first and second fan rings 32, 33 and each fin 4, as can be seen especially in FIG. It will be discharged through the formed opening 35.
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 as will be described later, the cooling fan 13 itself is surely and stably attached to the end face of the armature core. Since it is attached in such a manner, it is possible to increase the area of the opening 35 and the surface area of the fins 34 that serve as the air passages, thereby enhancing the cooling effect.

FIG. 6 is a detailed view showing an enlarged portion A cut along the line II shown in FIG. In FIG.
Reference numeral 10 is a coil, 16 is a core constituting an armature core, 17
Is a core blade portion, 18 is an insulating coating of the core 16, 1
9 is a winding gap, 31 is a pair of positioning bosses,
30 is a groove between two bosses in a pair.

As shown 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 the boss 31 is inserted into the gap of the winding portion of the armature core, It is provided so as to contact the insulated inner peripheral surface of the blade portion 17. This pair of two adjacent bosses 31
The groove 30 between them is provided slightly deeper than the end surface of the second fan ring 33 that is in contact with the end surface of the armature core, as indicated by a in FIG. Therefore, the boss 31 is easily bent inward (in the direction shown by the arrow in FIG. 6).

The side of the armature core 9 facing the winding portion is provided with a coating 18 for insulation, and this coating method is also usually carried out by spraying a powdery material to cure it. The thickness of the coating film is not constant, and even one armature core is not constant depending on its location. The boss 31 comes into contact with the inner peripheral surface of the core blade portion whose size is not constant, but as described above, the groove 30 is formed deeper than the end surface of the second fan ring 33.
Since the boss 31 is configured to be easily bent inward, variations in the thickness of the insulating coating layer can be absorbed and dealt with.

Further, the boss 31 is formed such that the boss tip is thicker than the ring-side boss root. To illustrate this, refer to FIGS. 7 and 8 which show cross-sections along the line II-II of FIG. As described above, when the boss 31 is inserted into the gap of the armature core winding portion, the boss 31 bends inward according to the variation in the thickness of the insulating coating layer. At that time, as shown in FIG. If the boss root 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 root of the boss rather than at its entire surface. Become.
In this case, the elastic force of the boss acts so as to lift the cooling fan away from the armature core, that is, to lift it. In order to prevent this, the present invention, as shown in FIG. 8, thins the root portion of the side surface of the boss, and does not contact the insulating coating at the root portion, but makes contact with the tip portion thereof. As a result, it is possible to suppress the force of the boss when the boss bends inward and prevent the cooling fan from rising. The armature core 9 is formed by using such a boss 31.
The second fan ring 33 of the cooling fan 13 positioned on the end surface of the is fixed to the end surface of the armature core 9 with an adhesive. At this time, in order to further increase the fixing force, a step for the purpose of collecting the adhesive is provided. this is,
It is shown as a groove 29 in FIGS. 3 and 5. In addition, the second fan ring 3 adhered to the end surface of the armature core 9
On the surface of FIG. 3, an appropriate number of protrusions 40 are provided between the bosses 31, for example, on both sides of the pair of bosses 31 as shown in FIGS. A space for attaching the adhesive is secured when the adhesive is used. Figure 2
2, 23, a high viscosity adhesive, for example 0.6-
Use an adhesive with a viscosity of about 0.7 mm and 1
When attached to the end face of the armature core with a width of mm, the height of the protrusion is 0.5
A good adhesion effect can be obtained by setting the thickness to about mm.
In this way, the cooling fan is not a commutator that generates heat, but is bonded to the end face of the armature core, so that 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, epoxy type,
Urethane-based or ester-based adhesives can be used. When using a low-viscosity adhesive, the step shown as the groove 29 in FIG. 3 or FIG. 5 corresponds, and when using a high-viscosity adhesive, the protrusion 40 as shown in FIGS. It can be dealt with.

Further, as shown in FIG. 4 or 5, the fins 34 of the cooling fan 13 of the present invention are angled toward the tip from the middle of the fin, and the thickness of the fin is reduced on the tip side. . This causes the wind to be directed radially outwards regardless of the direction of rotation of the motor and hence the cooling fan.

In order to increase the cooling effect by letting out more air from the air holes 6 formed in the housing 1 on the outer side of the fins 34 of the cooling fan 13 in the radial direction, the air from the fins 34 is directed toward the fins 34. It is desirable to be oriented radially outward from the fins 34 as much as possible rather than perpendicular to the surface. However, in the case of a motor that requires forward and reverse rotation, this cannot be achieved by forming the cooling fins 34 into, for example, a dogleg shape or an arc shape.

According to the present invention, the fin shape of the cooling fan is configured as described above, so that the wind can be directed to the outer side in the radial direction regardless of whether the fan is rotated in the forward or reverse direction, thus improving the cooling effect. Can be made.

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

The 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 that of the first embodiment of 5 pairs in that the number of the positioning bosses 31 is 3, as shown in FIG. The same as in the first embodiment.

FIG. 19 shows the results of an experiment in which the case surface temperature was measured for Conventional Technique 1, Conventional Technique 2, and the present invention. The horizontal axis represents the passage of measurement time, and the vertical axis represents
It represents the change in temperature measured on the case surface. Regarding the prior art 1 and the present invention, the standard case and the one with the addition of the air holes were measured, but in each case,
It can be seen that the present invention has a lower temperature rise and a better cooling effect than the prior art. According to the measurement result, the prior art 2 is the most inferior in terms of the cooling effect, even though there is an effect that it is not necessary to fix the cooling fan on the commutator surface having a high temperature as described above.

FIG. 20 is a left side view and a front view of a 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 that is adhered to the end face of the armature core. 33
It is possible to secure a space for attaching an adhesive between the core and the end surface of the iron core 9. The height of the protrusion 40 is preferably 0.4 to 0.6 mm, though it depends on the viscosity of the adhesive. FIG. 21 shows a case where it is applied to a three-pole cooling fan.

FIG. 22 shows the cooling fan 13 shown in FIG.
It shows a configuration in which 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 pair 31. An adhesive 41 can be attached between the protrusions to attach a cooling fan. The axial height of the protrusion 40 is 0.4 to 0.6 mm.
Since it is set to, the protrusion 40, the second fan ring 3
3. The portion surrounded by the end face of the armature core 9 becomes an “adhesive pool”, and the fixing force can be increased as compared with the case where the second fan ring and the end face of the armature core are directly bonded.

[0035]

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

The boss provided on the second fan ring is
Although it contacts the insulating coating layer on the inner peripheral surface of the core blade where the dimensions of the armature core are not constant, a groove is formed deeper than the end surface of the second fan ring, and the boss is configured to bend easily inward. It is possible to absorb and respond to variations in layer thickness. In addition, by making the root part of the boss thinner and contacting the tip part of the boss without contacting with the insulating coating, the force of the boss when it bends inward is suppressed and the cooling fan Lifting can be prevented.

In the cooling fan, the second fan ring is fixed to the end surface of the armature core by using an adhesive. At this time, a step for the purpose of accumulating the adhesive, or a space for applying the adhesive by a protrusion. Since the is provided, the fixing force can be further increased.

Further, the fin of the cooling fan of the present invention is
By providing the angle toward the tip from the middle of the fin, it is possible to direct the wind outward in the radial direction regardless of the rotation direction of the motor and therefore the cooling fan, and improve the cooling effect.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an essential part of a 5-pole rotor small-sized motor incorporating a cooling fan according to a first embodiment.

FIG. 2 is a right side view showing the five-pole rotor in the first embodiment.

FIG. 3 is a front view of the cooling fan according to the first embodiment.

FIG. 4 is a right side view of the cooling fan according to the first embodiment.

FIG. 5 is a left side view of the cooling fan according to the first embodiment.

FIG. 6 is a detailed cross-sectional view of a portion A of FIG.

7 is a detailed cross-sectional view taken along the line II-II in FIG. 6 when the boss root is not thinned.

FIG. 8: Line II-I in FIG. 6 when the boss root is thin
It is a detailed sectional view taken along line I.

FIG. 9 is a view showing the cooling fan of the second embodiment mounted with 3
It is a front view of a polar rotor.

FIG. 10 is a right side view of the three-pole rotor to which the cooling fan of the second embodiment is attached.

FIG. 11 is a front view of a cooling fan according to a second embodiment.

FIG. 12 is a left side view of the cooling fan according to the second embodiment.

FIG. 13 is a vertical cross-sectional view of a main part of a small motor including a cooling fan according to the related art 1.

FIG. 14 is a front view showing a rotor of prior art 1.

FIG. 15 is a right side view showing a rotor of prior art 1.

FIG. 16 is a right side view of only the cooling fan of the related art 1.

FIG. 17 is a cross-sectional view of a cooling fan of prior art 2.

FIG. 18 is a side view of a cooling fan of prior art 2.

FIG. 19 shows the experimental results of measuring the case surface temperature for Conventional Technique 1, Conventional Technique 2, and the present invention.

20A and 20B are a left side view and a front view of a 5-pole cooling fan provided with protrusions.

FIG. 21 is a left side view of a three-pole cooling fan provided with protrusions.

FIG. 22 is a front view of a rotor to which a cooling fan having protrusions is adhered.

FIG. 23 is a sectional view taken along the line III-III in FIG. 23, and is an enlarged view of a bonded 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 brushes 15 shaft 16 cores 17 core blade 18 Insulation coating 19 Winding gap 29 Ring groove 30 Groove between bosses 31 Positioning boss 32 First Fan Ring 33 Second Fan Ring 34 fins 35 opening 40 protrusions 41 adhesive

Continuation of the front page (56) Reference JP-A-63-1341 (JP, A) JP-A-5-87091 (JP, A) JP-A-8-326693 (JP, A) JP-A-8-308657 (JP , A) JP-A-7-336924 (JP, A) JP-A-5-207692 (JP, A) JP-A-4-207935 (JP, A) JP-A-8-331807 (JP, A) 62-56800 (JP, U) Actual development Sho 62-168771 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02K 9/00-9/28 H02K 7/00-7 / 20 F04D 29/18-29/38

Claims (6)

(57) [Claims] 1. A housing having a bottomed hollow cylindrical shape and having a permanent magnet fixed to the inner peripheral surface thereof, an end plate fitted into an opening of the housing, and a coil facing the permanent magnet. A rotor comprising a wound armature core and a commutator, and a brush slidably engaged with the commutator, air holes are provided in the housing and end plates, and a cooling fan is provided in the rotor. In the small-sized motor integrally formed, the cooling fan includes a first fan ring, a second fan ring, a plurality of fins provided at equal intervals in the circumferential direction, and a second fan ring. A plurality of bosses provided on an end surface of the fan ring, wherein the plurality of fins form an opening serving as an air passage between them and the first fan ring and the second fan ring; First fa The ring has an inner peripheral surface having a diameter larger than that of the commutator outer peripheral surface to form an air passage therebetween, and the second fan ring has the bosses provided on the second fan ring wound on an armature core. A small motor characterized in that it is positioned by being inserted into the gap of the wire portion, and its end face is adhered to the end face of the armature core with an adhesive agent, whereby the cooling fan is fixed to the rotor. . 2. The plurality of bosses are configured in pairs of two, and when the bosses enter the winding portion gap, the outer peripheral side surface of the boss is the core blade portion of the armature core. The small motor according to claim 1, wherein the groove that is in contact with the inner surface and that is between the pair of bosses is deeper than the end surface of the second fan ring. 3. The small motor according to claim 1, wherein each of the plurality of bosses has a tip portion thicker than a root portion of the boss on the fan ring side. 4. The small motor according to claim 1, wherein a groove for accumulating an adhesive is provided on an end surface of the second fan ring which is adhered to an end surface of the armature core. . 5. The projection according to claim 1, wherein a projection is provided between the bosses to secure a space for the adhesive on the end surface of the second fan ring bonded to the end surface of the armature core. Small motor described in. 6. The small motor according to claim 1, wherein the fins of the cooling fan are made thinner from the middle to the tip.