JPH08182242A - Dustproof structure of bearing for motor - Google Patents

Abstract

PURPOSE: To surely prevent instrusion of dust into a bearing without increasing the man-hour required for assembling and machining work or the number of components, and to prevent the rotational resistance of a rotary shaft from increasing. CONSTITUTION: A motor housing 12 having an opening 12a at one end thereof is provided, at the other end thereof, with a bearing holding part having an insertion hole and an insertion hole 13a is made oppositely to the insertion hole in a head 13 fixed to one end of the housing. A rotary shaft 14 is held at the opposite ends thereof by first bearing 21 and a second bearing inserted into respective insertion holes. A cooling fan 23 is fitted, at a boss 23a thereof, over the rotary shaft such that the boss 23a abuts against the first bearing having a outer ring 21a being retained by means of a bearing retainer 24 fitted idly to the rotary shaft. An inner ring 24b projects from the inner circumferential edge of the retainer toward the fan and an outer ring 23e is projected from the fan toward the retainer to define a labyrinth along with the boss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dustproof structure suitable for a bearing for rotatably holding a rotating shaft of a motor used in a power tool, particularly a hand grinder, a hand drill and the like.

[0002]

2. Description of the Related Art Conventionally, as a bearing dustproof structure of this type, a rotating shaft is rotatably held in a casing A through a bearing, and a casing B having a dust collecting fan chamber is connected to the casing A to output the output of the rotating shaft. A dust collecting fan shaft that is inserted into the dust collecting fan chamber is integrally provided at an end portion, and the dust collecting fan that is fitted to the dust collecting fan shaft close to the bearing is housed in the dust collecting fan chamber. There is disclosed a dust collecting hammer drill in which a labyrinth is formed between the back surface of the dust collecting fan and the casing A (Actual Kaihei 3-59111). In this dust collecting hammer drill, the felt is arranged in the groove of the casing A forming the labyrinth, and the convex portion of the dust collecting fan forming the labyrinth is in contact with the felt. With the dust collecting hammer drill configured in this way, dust is generated during the drilling work of concrete etc. with this drill, and this dust flows into the dust collecting fan chamber by the suction force of the dust collecting fan, but this dust is the labyrinth. Also, it is blocked by the felt so that it does not enter the bearing.

On the other hand, the rotating shaft is surrounded by the housing and is held by a bearing, the outer peripheral portion of the bearing is substantially completely surrounded by a bearing cap, and a seal portion is formed at one end of the cap and the other end is formed. Japanese Patent Laid-Open No. 57-117421 discloses a dustproof mechanism for a bearing in which a folded-back portion is provided at an end and a seal portion of a cap is configured to slide in contact with an outer circumference of a rotary shaft. In the bearing dustproof mechanism thus configured, since the bearing is substantially completely surrounded by the bearing cap, dust does not enter the bearing and the life of the bearing can be extended.

[0004]

However, in the above-mentioned conventional dust collecting hammer drill, it is necessary to form a groove for forming a labyrinth in the casing A, and there is a problem that the shape of the casing A is restricted. Further, in the above dust collecting hammer drill, the felt has to be arranged in the groove of the casing A, and there is a problem that the number of parts called this felt increases and the number of assembling steps increases, so that the convex part of the dust collecting fan always contacts the felt. However, there is also a problem that this contact increases the rotational resistance of the rotary shaft. Further, in the above-mentioned conventional bearing dust-proof mechanism, since the bearing cap is in the shape of a bag, there are problems that the number of steps for assembling the cap to the bearing is increased and that molding of the cap is relatively difficult. Further, in the above-mentioned bearing dustproof mechanism, the seal portion of the bearing cap is always in contact with the rotary shaft, and this contact also causes a problem that the rotational resistance of the rotary shaft increases.

An object of the present invention is to reliably prevent dust from entering the bearing without increasing the number of assembling steps, the number of processing steps, and the number of parts, and for a motor that does not increase the rotational resistance of the rotary shaft. It is to provide a dustproof structure of the bearing.

[0006]

The structure of the present invention for achieving the above object will be described with reference to FIGS. 1, 2 and 5 corresponding to the embodiments. The first aspect of the present invention is, as shown in FIGS. 1 and 5, a cylindrical motor in which an opening 12a is formed at one end and a bearing holder 12b having an insertion hole 12c or a through hole is integrally provided at the other end. The housing 12, a bearing holder 13 attached to one end of the housing 12 so as to cover the opening 12a and having an insertion hole 13a formed so as to face the insertion hole 12c or the through hole, and an insertion hole near the one end serving as an output end. The rotary shaft 14 is rotatably held at the other end via the first bearing 21 inserted in 13a and the second bearing 22 inserted in the insertion hole 12c or the through hole. A cooling fan 23 having a boss 23a abutting against or closely fitted to the bearing 21 and a large number of blades 23b integrally formed on the boss 23a, and a first bearing of the rotary shaft 14. 21 and inserting the first bearing 21 is loosely fitted between the fan 23 hole 13
Bearing pressing plate 24 for fixing the outer ring 21a of the first bearing 21 to the bearing holder 13 in a state of being inserted in a
It is an improvement of the motor provided with. Its characteristic configuration is
An inner ring 24b projects from the inner peripheral edge of the bearing retainer plate 24 toward the fan 23, and an outer ring 23e projects from the fan 23 toward the bearing retainer plate 24. The outer ring 23e, the inner ring 24b, and the boss 2 are provided.
The labyrinth 25 is formed by 3a.

The second aspect of the present invention is, as shown in FIGS. 2 and 5, a cylinder integrally formed with an opening 12a at one end and a bearing holding portion 12b having an insertion hole 12c or a through hole at the other end. -Shaped motor housing 12 and housing 12
The insertion hole 1 is attached to one end of the so as to cover the opening 12a.
2c or the through hole, and the bearing holder 13 in which the insertion hole 13a is formed, and the other end through the insertion hole 12c or through the first bearing 21 inserted in the insertion hole 13a in the vicinity of one end serving as the output end. The second bearing 22 inserted in the hole
A rotary shaft 14 rotatably held via
A bearing cap 26 which is interposed between the insertion hole 12c or the through hole and the second bearing 22 and covers at least the outer peripheral surface of the second bearing 22, and an end surface of the second bearing 22 exposed from the insertion hole 12c or the through hole. It is an improvement of a motor provided with a dustproof ring 27 fitted to the rotary shaft 14 so as to cover it. The characteristic structure is that the dustproof ring 27 is formed in a hat shape, and the labyrinth 28 is formed by the ring 27, the inner peripheral edge of the insertion hole 12c or the through hole, and the end portion of the cap 26.

[0008]

[Function] The fan 23 that rotates with the rotation of the rotary shaft 14
As a result, an air flow containing dust is generated in the motor housing 12 from the other end toward one end. However, dust enters the first bearing 21 due to the labyrinth 25 formed by the outer ring 23e, the inner ring 24b, and the boss 23a. In addition, the labyrinth 28 formed by the dust-proof ring 27 and the inner peripheral edge of the insertion hole 12c or the through hole and the end of the cap 26 prevents dust from entering the second bearing 22.

[0009]

An embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIGS. 1 to 5, the motor 11 of the hand grinder 10 is an AC commutator motor in this example, and has a cylindrical motor housing 12 having an opening 12a at one end and an opening at one end of the housing 12. A head 13 mounted so as to cover the portion 12a, and a housing 12
And a rotary shaft 14 rotatably held by the head 13. The housing 12 is made of resin or aluminum alloy, and the other end of the housing 12 has an insertion hole 12c.
The bearing holding portion 12b having the above is provided integrally with the housing 12 (FIGS. 2 and 5). An insertion hole 13a formed in the head 13 so as to face the insertion hole 12c;
Bevel pinion 16 and bevel gear 17 that mesh with each other
And a gear housing portion 13b in which
And FIG. 5). An armature iron core 18 is fitted to the rotating shaft 14 substantially in the center thereof in the longitudinal direction.
9 is applied (FIG. 5). The first bearing 2 inserted into the insertion hole 13a is provided in the vicinity of one end which is the output end of the rotary shaft 14.
1 is press-fitted (FIGS. 1, 4, and 5), and the second bearing 22 inserted into the insertion hole 12c is press-fitted at the other end of the rotary shaft 14 (FIGS. 2 and 5). The bevel pinion 16 is fitted to the output end of the rotary shaft 14 (FIGS. 1, 4, and 5).

A cooling fan 23 is provided on the rotary shaft 14 so as to be located between the first bearing 21 and the armature core 18.
Are fitted (FIGS. 1, 4 and 5). This fan 23
Is a centrifugal fan, the inner ring 21b of the first bearing 21
And a plurality of blades 23b integrally formed on the boss 23a. A pipe-shaped core metal 23c made of steel or aluminum alloy is embedded in the boss 23a.
The boss 23 a is fitted to the rotary shaft 14 by press-fitting the boss 23 into the knurled portion 14 a formed on the rotary shaft 14. An annular diffuser ring 23d, which plays a role of a diffuser, is provided around the outer periphery of the multiple blades 23b.
It is provided integrally with b, and the gap between the outer peripheral surface of the ring 23d and the inner peripheral surface of the housing 12 is 0.5 to 1.0 m.
It is set within the range of m. This eliminates the need for a baffle (not shown) that has conventionally played the role of a diffuser, can reduce the number of parts and the manufacturing cost, and can prevent foreign matter from being trapped between the blade 23b and the baffle. It is like this.

The rotary shaft 14 is located between the first bearing 21 and the blades 23b of the fan 23, and the boss 23a.
The bearing retainer plate 24 is loosely fitted so as to be located on the outside. The holding plate 24 has a pair of claws 24a, 24a at both ends.
Respectively (FIGS. 3 and 4). These nails 24
Reference numerals a and 24a denote a pair of recesses 1 formed so as to sandwich two mounting holes 13d and 13f, which are diagonally located, out of the four mounting holes 13c to 13f of the head 13 to the housing 12.
The outer ring 21a of the first bearing 21 in the insertion hole 13a is inserted into the outer ring 21a of the head 1 by being loosely inserted into each of 3g and 13h and pressed by one end surface of the housing 12 to elastically deform.
It is designed to be fixed to 3. Bearing retainer plate 24
An inner ring 24b is projected from the inner peripheral edge of the fan toward the fan 23, and an outer ring 23e is projected from the fan 23 toward the bearing pressing plate 24. Outer ring 23
e is located outside with a predetermined gap from the outer surface of the inner ring 24b.
The labyrinth 25 is formed by b and the boss 23a (FIGS. 1, 4, and 5).

On the other hand, the insertion hole 12c and the second bearing 22
A bearing cap 26 made of rubber or resin is interposed between the outer peripheral surface of the second bearing 22 and the outer ring 22 of the bearing 22.
Of the both end faces of a, the end face opposite to the end face exposed from the insertion hole 12c is covered (FIGS. 2 and 5). The dustproof ring 27 is attached to the rotary shaft 14 so as to cover the end surface of the second bearing 22 exposed from the insertion hole 12c.
The ring 27 is formed of resin or aluminum alloy into a hat shape having a collar portion 27a at the outer peripheral edge. Further, a plurality of convex portions 27b are provided on the outer peripheral surface of the collar portion 27a at equal intervals. The outer diameter of the dustproof ring 27 is formed to be substantially the same as the outer diameter of the bearing cap 26.
7a is provided away from the outer ring 22a of the second bearing 22 by a predetermined distance in the axial direction. Bearing holder 12
The dustproof ring 2 is provided on the peripheral wall forming the insertion hole 12c of b.
A ring-shaped protrusion 12d is provided so as to cover the outer peripheral surface of the dustproof ring 27 with a predetermined gap from the outer peripheral surface of 7. The end portion of the cap 26 facing the dustproof ring 27 is formed to extend toward the flange portion 27a of the ring 27, and the end portion of the cap 26 formed to extend toward the flange portion 27a and the flange portion 27a. A predetermined gap is formed between them.
Dustproof ring 27, inner peripheral edge of insertion hole 12c, and cap 26
A labyrinth 28 is formed by the ends of the. Reference numerals 21c and 22c denote metal or rubber seal members that are preassembled on both end surfaces of the first and second bearings 21 and 22 (FIGS. 1, 2 and 4).

In the dust-proof structure of the motor bearing constructed as described above, when the rotary shaft 14 rotates, the shaft 14 rotates.
As the fan rotates, the fan 23 rotates to generate an air flow for cooling the motor 11 from the other end to the one end in the motor housing 12. The air flow contains a relatively large amount of dust such as metal powder ground by the disc-shaped grindstone 29, but the labyrinth 25 formed by the outer ring 23e, the inner ring 24b, and the boss 23a causes the first bearing 2 to rotate.
Dust does not enter the inside of 1, and the dustproof ring 27 and the insertion hole 12
The labyrinth 28 formed by the inner peripheral edge of c and the end of the cap 26 prevents dust from entering the second bearing 22. At the entrance of the labyrinth 28, a dustproof ring 27
Since the plurality of convex portions 27b provided on the upper end rotate to knock off the dust, the dust does not lean on the labyrinth 28 either. As a result, the first and second bearings 21,
22 has a longer life.

Although the dustproof structure of the present invention is applied to the bearing of the motor of the hand grinder in the above embodiment,
The dustproof structure of the present invention may be applied to a bearing of a motor such as a hand drill, an electric circular saw, or a dust collector. In addition, although an AC commutator motor is used as the motor in the above-described embodiments, a DC commutator motor, an induction motor, a synchronous motor or another motor may be used. Further, in the above-described embodiment, the bearing holding portion integrally provided at the other end of the motor housing has the insertion hole in which the insertion inner surface is closed. However, if the second bearing can be inserted, the insertion inner surface is opened. It may be a through hole. In this case, it is necessary to completely cover the end surface of the second bearing facing the insertion inner surface with a bearing cap in order to prevent dust from entering the second bearing. Further, in the above embodiment, the cooling fan boss and the first
Although the boss is brought into contact with the inner ring of the bearing, the boss may be brought close to the inner ring of the first bearing to form a predetermined gap between the boss and the inner ring.

[0015]

As described above, according to the present invention, the inner ring is projected from the inner peripheral edge of the bearing retainer plate for fixing the outer ring of the first bearing to the bearing holder toward the cooling fan. Since the outer ring is projected toward the bearing retainer plate and the labyrinth is formed by the outer ring, the inner ring and the boss, even if the air flow containing dust flows into the motor housing by the cooling fan, 1 No dust will enter the bearing. Further, in comparison with the conventional dust collecting hammer drill in which the shape of the casing A is restricted and the space for mounting the bearing retainer plate for fixing the outer race of the bearing to the housing cannot be secured, the present invention ensures the outer race of the first bearing by the bearing retainer plate. Can be fixed to the bearing holder. Further, compared with the conventional dust collecting hammer drill in which the number of parts called felt is increased and the number of assembling steps is increased, the number of assembling steps and the number of parts are not increased in the present invention, and the manufacturing cost is not increased. Further, in comparison with the conventional dust collecting hammer drill in which the rotation resistance of the rotating shaft increases due to the contact of the convex portion of the dust collecting fan with the felt, the present invention does not have such contact in the dustproof structure, so that rotation of the rotating shaft is prevented. The resistance does not increase.

Further, a dustproof ring fitted to the rotary shaft is formed in a hat shape so as to cover the end surface of the second bearing exposed from the insertion hole or the through hole, and the ring and the inner peripheral edge of the insertion hole or the through hole and the cap are formed. If the labyrinth is formed by the end portions, even if an air flow containing dust flows into the motor housing, the labyrinth does not allow dust to enter the second bearing. In addition, the number of assembly steps of the bag-shaped bearing cap to the bearing is increased, and the present invention does not increase the number of assembly steps as compared with the conventional dust-proof mechanism of the bearing in which molding of the cap is relatively difficult. There is no pushing up.
Further, as compared with the conventional dustproof mechanism of the bearing in which the rotation resistance of the rotary shaft increases due to the contact of the seal portion of the bearing cap with the rotary shaft, in the present invention, the dustproof structure portion does not have such contact, so Rotational resistance does not increase.
Further, if a plurality of protrusions are provided on the outer peripheral surface of the dust-proof ring, the dust is knocked off by the rotation of the protrusions and is prevented from leaning on the labyrinth.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a portion A in FIG. 5 showing a dustproof structure of a bearing for a motor according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a B part in FIG.

FIG. 3 is a sectional view taken along the line CC of FIG.

FIG. 4 is a sectional view taken along the line DD of FIG.

5 is a cross-sectional view taken along the line EE of FIG.

[Explanation of symbols]

 11 Motor 12 Motor Housing 12a Opening 12b Bearing Holding 12c Insertion Hole 13 Head (Bearing Holder) 13a Insertion Hole 24b Inner Ring 14 Rotating Shaft 21 First Bearing 21a First Bearing Outer Ring 22 Second Bearing 23 Cooling Fan 23a Boss 23b Blade 23e Outer ring 24 Bearing retainer plate 25,28 Labyrinth 26 Bearing cap 27 Dustproof ring

Claims (2)

[Claims] 1. A cylindrical motor housing (12) integrally formed with an opening (12a) at one end and a bearing holder (12b) having an insertion hole (12c) or a through hole at the other end. An insertion hole which is attached to one end of the housing (12) so as to cover the opening (12a) and faces the insertion hole (12c) or the through hole.
(13a) is formed in the bearing holder (13), and the other end is the insertion hole (12c) through the first bearing (21) inserted in the insertion hole (13a) near one end serving as an output end. Alternatively, the rotary shaft (14) rotatably held through the second bearing (22) inserted into the through hole and the rotary shaft (14) contacting or approaching the first bearing (21). Boss
(23a) and a cooling fan (23) having a large number of blades (23b) integrally formed with the boss (23a), and the rotating shaft (14)
Among them, the first bearing (21) is loosely fitted between the first bearing (21) and the fan (23), and the first bearing (21) is inserted into the insertion hole (13a).
The outer ring (21a) of the first bearing (21) when inserted into the
To the bearing holder (13).
4), the fan (23) from the inner peripheral edge of the bearing retainer plate (24)
Inner ring (24b) is projected toward, the outer ring (23e) is projected from the fan (23) toward the bearing retainer plate (24), the outer ring (23e) and the inner ring ( A dustproof structure for a motor bearing, wherein a labyrinth (25) is formed by 24b) and the boss (23a). 2. A cylindrical motor housing (12) integrally formed with an opening (12a) at one end and a bearing holder (12b) having an insertion hole (12c) or a through hole at the other end. An insertion hole which is attached to one end of the housing (12) so as to cover the opening (12a) and faces the insertion hole (12c) or the through hole.
(13a) is formed in the bearing holder (13), and the other end is the insertion hole (12c) through the first bearing (21) inserted in the insertion hole (13a) near one end serving as an output end. Or, between the rotary shaft (14) rotatably held through the second bearing (22) inserted in the through hole and the insertion hole (12c) or the through hole and the second bearing (22). A bearing cap (26) interposed between the second bearing (22) and at least the outer peripheral surface of the second bearing (22), and an end surface of the second bearing (22) exposed from the insertion hole (12c) or the through hole. In a motor having a dustproof ring (27) fitted in the rotating shaft (14), the dustproof ring (27) is formed in a hat shape, and the ring (27) and the insertion hole (12c) or through hole Dustproof structure for motor bearing, characterized in that a labyrinth (28) is formed by the inner peripheral edge of the cap and the end of the cap (26). .