CN110520251B

CN110520251B - Power tool

Info

Publication number: CN110520251B
Application number: CN201880022484.6A
Authority: CN
Inventors: 宫城贵则; 清水裕之; 远藤大辅
Original assignee: Nitto Kohki Co Ltd
Current assignee: Nitto Kohki Co Ltd
Priority date: 2017-03-29
Filing date: 2018-03-22
Publication date: 2022-09-20
Anticipated expiration: 2038-03-22
Also published as: GB2573953A; TWI677412B; CN110520251A; KR20190116429A; GB2573953B; KR102303876B1; WO2018180835A1; TW201900356A; JP6581725B2; GB201912066D0; DE112018001786T5; JPWO2018180835A1

Abstract

The invention provides a power tool which can enter the inner part of a shell more easily and safely. A power tool (10) is provided with a commutator motor (14) in a housing (12), and the housing (12) is provided with: the portable terminal includes a first housing section (30), a second housing section (32) movable relative to the first housing section (30), a tapping screw (34) fixing them, and a cover (36) sandwiched between the first housing section (30) and the second housing section (32). When the tapping screw (34) is unscrewed, the tapping screw (34) is displaced in a direction away from the first housing section (30), engages with the engagement ring (50) of the second housing section (32), and further displaces the second housing section (32) in the direction away from the first housing section. The cover (36) is thereby in a removable state. When the tapping screw (34) is tightened, the second housing section (32) is displaced in a direction approaching the first housing section (30) by the tapping screw (34), and returns to a state where the cover (36) is clamped.

Description

Power tool

Technical Field

The present invention relates to a power tool having a power unit in a housing.

Background

In a power tool having a power unit in a housing, an operator usually performs maintenance on the power unit and the like disposed in the housing by detaching the housing. For example, patent document 1 discloses a grinding machine including a commutator motor as a power unit in a housing including a motor housing and a rear cover. In general, a commutator motor supplies current to a rotor by bringing carbon brushes into contact with a commutator rotating together with the rotor, but the carbon brushes are gradually worn by friction with the rotating commutator, and therefore need to be replaced periodically. In this grinder, the fixing screw for fixing the rear cover to the motor case is removed to remove the rear cover, and then the carbon brush is replaced.

Prior art documents

Patent literature

Patent document 1: japanese patent laid-open publication No. 2007 & 152479

Disclosure of Invention

Problems to be solved by the invention

In the power tool in which a part of the housing needs to be removed for maintenance of the power unit disposed in the housing as in the conventional grinding machine described above, the removed screw may be lost, and a delicate operation is required for attaching the screw once removed, which is troublesome. Further, when a part of the housing is removed, components such as electronic circuits and wiring disposed in the housing are exposed to the outside, and thus, these components may be damaged.

In view of the above-described problems of the prior art, an object of the present invention is to provide a power tool including a power unit in a housing, the power tool being capable of more easily and safely entering the inside of the housing.

Means for solving the problems

That is, the present invention is a power tool including a power unit in a housing, wherein,

the housing includes:

a first housing section;

a second housing section displaceable relative to the first housing section;

a fixing mechanism for fixing the second housing section to the first housing section;

an interior access opening for accessing an interior of the housing; and

a cover that is sandwiched between the first housing section and the second housing section after being fixed by the fixing mechanism to close the internal access opening,

the fixing mechanism is displaced in a direction away from the first housing part when rotated in a first direction and displaced in a direction toward the first housing part when rotated in a second direction opposite to the first direction,

the fixing mechanism is configured to engage with the second housing section in the direction away from the first housing section when the fixing mechanism is rotated in the first direction and displaced in the direction away from the first housing section, thereby displacing the second housing section in the direction away from the first housing section to release the clamping, and the cover can be removed from between the first housing section and the second housing section,

when the fixing mechanism is rotated in the second direction and displaced in a direction approaching the first housing portion, the fixing mechanism engages with the second housing portion in the direction approaching the second housing portion, thereby displacing the second housing portion in the direction approaching the second housing portion, and clamping the cover between the first housing portion and the second housing portion.

In this power tool, the second housing section is displaced by rotating a fixing mechanism for fixing the second housing section to the first housing section, and the cover can be removed. With this configuration, the fixing mechanism and the second casing section can be accessed without completely removing them from the first casing section. Therefore, when the power unit in the housing is taken into the housing for maintenance or the like, the fixing mechanism can be prevented from being lost, and the possibility that the power unit or the like is damaged by the power unit and other components in the housing being excessively exposed to the outside can be reduced. Further, when the cover is returned to the original state in which it is clamped, the fixing mechanism and the second housing section need not be attached to the first housing section again, and the fixing mechanism only needs to be rotated, so that the work can be performed more easily than in the conventional power tool.

The fixing means may be a fixing screw that is screwed into the first housing portion, and that is loosened when rotated in the first direction and tightened when rotated in the second direction.

More specifically, the present invention may be, in addition,

the set screw has a shaft portion and a head portion,

the second housing part has: an insertion hole through which the shaft portion is inserted; a recess connected to the insertion hole and receiving the head; a screw head engaging portion configured to cover a portion of the head portion and retain the head portion within the recess,

when the fixing screw is unscrewed by screwing, the head of the fixing screw engages with the screw head engaging portion, and the second housing section is displaced in the direction away from the screw head engaging portion. In this case, the screw head engaging portion may have a ring shape having a central opening, and the screw head engaging portion may be configured to be capable of screwing the fixing screw by inserting a tool into the central opening.

Further, the first housing portion may have a resin-made inner extension portion to which the fixing screw is screwed, and the fixing screw may be a tapping screw screwed into the inner extension portion.

With this configuration, it is not necessary to form a female screw portion into which a fixing screw is screwed in the manufacturing process of the first housing portion, and the manufacturing cost of the component can be reduced.

Further, the first housing portion may have a first locking portion, the second housing portion may have a second locking portion that is engaged with the first locking portion,

the engagement between the first locking portion and the second locking portion restricts a displacement range in which the second housing portion is displaced in the direction of the separation relative to the first housing portion, and the fixing mechanism is not completely detached from the first housing portion in the displacement range.

Specifically, the second locking portion may be a locking screw screwed into the second housing portion, the first housing portion may have an elongated hole for receiving a tip end portion of the locking screw, and an end portion of the elongated hole may be the first locking portion.

With this configuration, the second housing section is not displaced more than necessary. In addition, since the fixing screw cannot be removed from the first housing portion, the fixing screw can be more reliably prevented from being lost.

Specifically, the power unit may be a commutator motor having brushes disposed at a position where the brushes can be replaced through the internal access opening.

Hereinafter, embodiments of the power tool according to the present invention will be described with reference to the drawings.

Drawings

Fig. 1 is a side view of a power tool according to an embodiment of the present invention.

Fig. 2 is a top view of the power tool of fig. 1.

Fig. 3 is a side sectional view taken along line III-III of fig. 2.

Fig. 4 is a top sectional view taken along line IV-IV of fig. 3.

Fig. 5 is a first main part sectional view showing a removing action of the cover.

Fig. 6 is a second main part sectional view showing the removing action of the cover.

Fig. 7 is a third main part sectional view showing the removing operation of the cover.

Fig. 8 is a fourth main part sectional view showing the removing operation of the cover.

Fig. 9 is a top sectional view along the line IV-IV of fig. 3 in a state where the second housing part has been displaced to the position of fig. 7.

Detailed Description

As shown in fig. 1 to 3, a power tool 10 according to an embodiment of the present invention is an electric power tool including a commutator motor 14 as a power unit in a housing 12. A tool output shaft 20 drivingly connected to the rotation output shaft 16 of the commutator motor 14 via a bevel gear 18 is provided with a required member such as a disk-shaped polishing pad according to the application.

As shown in fig. 3, the commutator motor 14 includes: a rotor 22 mounted to be rotatable relative to the housing 12; a stator 24 disposed around the rotor 22 and fixed to the housing 12; and two brushes 26 arranged to contact the commutator 23 attached to the rotor 22. A switch 28 is mounted on the housing 12, and the driving of the commutator motor 14 is started/stopped by operating the switch 28. The brush 26 slides with the commutator 23 rotating at a high speed, and thus gradually wears. Therefore, after the power tool 10 is used for a certain period of time, the brush 26 needs to be replaced with a new one.

The housing 12 has: a first housing part 30 that holds the commutator motor 14; a second housing section 32 attached to the rear of the first housing section 30; a tapping screw (fixing mechanism, fixing screw) 34 that fixes the second casing section 32 to the first casing section 30; and two covers 36 held by being sandwiched between the first and

second casing sections

30 and 32. The second housing section 32 is attached to the first housing section 30 such that the front end portion 32a covers the outer peripheral surface 30a of the rear end portion of the first housing section 30, and is slidably displaceable in the direction of the longitudinal axis L with respect to the first housing section 30. Between the rear end recess 30b of the first case section 30 and the front end recess 32b of the second case section 32, an internal access opening 37 for accessing the interior of the case 12 is formed. The internal access opening 37 is closed by a cover 36 in the use state of the power tool 10. The first case portion 30 has an inner extension 38 extending into the second case portion 32, and a hole 40 into which the tapping screw 34 is screwed is formed in the inner extension 38. The tapping screw 34 is screwed into the hole 40 of the inner extension 38 while forming a thread groove in the side wall of the hole 40 and fixed. The first housing portion 30 is entirely formed of resin to facilitate screwing of the tapping screw 34 in the inner extension portion 38.

The second housing portion 32 has: an insertion hole 46 through which the shaft portion 42 of the tapping screw 34 is inserted; a recess 48 connected to the insertion hole 46 and receiving the head 44 of the tapping screw 34; and a metal engaging ring (screw head engaging portion) 50 that is press-fitted and fixed into the recessed portion 48 so as to cover the peripheral portion of the head 44 of the upper tapping screw 34 in the direction of the longitudinal axis L. The head 44 of the tapping screw 34 is held in the recess 48 by a snap ring 50. Therefore, the tapping screw 34 cannot be taken out from the second housing section 32. When the tapping screw 34 is screwed or unscrewed to or from the first housing portion 30, a tool such as a screwdriver is inserted through the central opening 52 of the engagement ring 50, and the tapping screw 34 is screwed. Instead of the structure in which the engaging ring 50 is press-fitted into the recess 48, a groove may be provided on the inner circumferential surface of the recess 48, and the screw head engaging portion may be configured by fitting a retaining ring into the groove.

A circuit board 60 is disposed on the internal extension portion 38 of the first case portion 30 so as to be covered by the second case portion 32. An LED62 for indicating the state of the power tool 10 is mounted on the circuit board 60. The circuit board 60 is put in a resin case and is mounted by sliding from the rear side (right side in the drawing) of the first housing portion 30 with respect to the inner extension portion 38 of the first housing portion 30. At a position of the second housing section 32 matching the LED62, a light diffusing member 64 for diffusing light of the LED62 is arranged. Thus, the light emitted from the LED62 is diffused by the light diffusion member 64, and the outer surface of the light diffusion member 64 emits light with substantially uniform brightness, so that the emission of the LED62 can be easily seen.

As shown in fig. 4, a locking screw (second locking portion) 54 extending in a direction orthogonal to the longitudinal axis L is further screwed into the second housing section 32. Further, an elongated hole 56 extending in the direction of the longitudinal axis L is formed in the inner extension portion 38, and the distal end portion 58 of the locking screw 54 is received in the elongated hole 56.

As described above, the brush 26 of the commutator motor 14 is worn by friction with the commutator 23, and therefore, needs to be replaced periodically. In the power tool 10, the brush 26 can be replaced in the following procedure.

First, as shown in fig. 5, the tapping screw 34 is screwed and loosened by left-handed (first direction) from a state where the second casing section 32 is fixed to the first casing section 30 by the tapping screw 34. Then, the tapping screw 34 is displaced in a direction (rightward as viewed in the drawing) away from the first housing part 30 along the longitudinal axis L, and the head 44 engages with the engaging ring 50 as shown in fig. 6. When the tapping screw 34 is further loosened, the engaging ring 50 is pressed against the head 44 of the tapping screw 34, and the second casing section 32 is displaced in a direction away from the first casing section 30 together with the tapping screw 34. When the second case section 32 is displaced to the position of fig. 7, the sandwiching of the cover 36 by the first case section 30 and the second case section 32 is released. Thereby, as shown in fig. 8, the cover 36 can be removed from between the first and

second casing sections

30 and 32.

When the second casing section 32 is at the position shown in fig. 7, as shown in fig. 9, the distal end portion 58 of the locking screw 54 engages with the end portion (first locking portion) 66 of the elongated hole 56, and the second casing section 32 cannot be displaced further in the direction away from the first casing section 30. That is, the displacement range of the second casing section 32 relative to the first casing section 30 is limited by the locking screw 54 and the end portion 66 of the elongated hole 56. The tapping screw 34 has a length that does not fall off the first housing section 30 within this displacement range.

As shown in fig. 8, when the cover 36 is removed, the inner access opening 37 closed by being covered with the cover 36 is exposed. Removal of the old brush 26 from the brush holder 70 and installation of the new brush 26 to the brush holder 70 can both be performed through the internal access opening 37. After a new brush 26 is attached to the brush holder 70, the cover 36 is attached again, and the tapping screw 34 is screwed and tightened by being screwed right-handed (in the second direction). Thus, the tapping screw 34 is displaced in a direction approaching the first casing section 30, engages with the second casing section 32, and displaces the second casing section 32 in the direction approaching. When returning to the state of fig. 5 in which the second casing section 32 is fixed to the first casing section 30, the cover 36 is again sandwiched between the first casing section 30 and the second casing section 32. The replacement operation of the brush 26 is thus completed.

In the power tool 10, when replacing components such as the brush 26 disposed in the housing 12, it is not necessary to remove the second housing section 32 and the tapping screw 34, which are part of the housing 12. Therefore, the components such as the circuit board 60 and the LED62 disposed inside the housing 12 are not exposed to the outside, and the possibility of damaging these components by carelessness is small. In addition, the tapping screw 34 can be prevented from being lost. The tapping screw is screwed into a hole while forming a thread groove in an inner peripheral surface of the hole of the object, but when the tapping screw once attached is removed and attached again to the same hole, the thread groove may be formed at a position different from the previous position. As a result, the strength of the inner circumferential surface of the hole is reduced, and the inner circumferential surface may be broken by repeating such operation a plurality of times, and the tapping screw may not be held. In the power tool 10, since the brushes 26 and the like can enter the housing 12 without removing the tapping screw 34 as described above, damage to the screw hole by the tapping screw 34 can be prevented. Further, since the displacement range of the second housing section 32 is restricted by the locking screw 54 and the elongated hole 56, the tapping screw 34 cannot be removed, and the tapping screw 34 is not removed carelessly, which can prevent the above-described problem more reliably.

The power tool 10 according to the embodiment of the present invention has been described, but the present invention is not limited thereto, and various modifications can be made. For example, the inner extension 38 of the first housing portion 30 into which the tapping screw 34 is screwed may be formed of resin, and the entirety of the first housing portion 30 is not necessarily required to be resin. As a fixing screw for fixing the second casing section 32 to the first casing section 30, a general screw may be used instead of the tapping screw 34. Wherein in this case, internal threads need to be preformed in the inner extension 38. Alternatively, a screw integrated with a washer may be used as the fixing screw, and the second housing portion 32 may be configured to hold the washer instead of the head 44 of the screw. The fixing mechanism between the second case 32 and the first case 30 may be a fixing mechanism other than a screw. For example, the following structure is also possible: the fixing mechanism is attached to the inner peripheral surface of the first housing portion so that the projection portion thereof engages with the inclined groove, and is rotated to displace the fixing mechanism in a direction away from and in a direction toward the first housing portion. The present invention is not limited to an electric power tool including a commutator motor, and is also applicable to a power tool including other power units such as a brushless motor, an air motor, and an engine. Further, the power tool includes a movable or fixed drill device, a machine tool such as a drill press, and the like.

Description of reference numerals:

a power tool 10; a housing 12; a commutator motor (power unit) 14; a rotary output shaft 16; a bevel gear 18; a tool output shaft 20; a rotor 22; a commutator 23; a stator 24; a brush 26; a switch 28; a first housing portion 30; outer peripheral surface 30 a: a rear end concave portion 30 b; a second housing portion 32; a front end portion 32 a; a front end concave portion 32 b; a tapping screw (fixing screw) 34; a cover 36; an interior access opening 37; an inner extension 38; a hole 40; a shaft portion 42; a head 44; an insertion through hole 46; a recess 48; an engaging ring (screw head engaging portion) 50; an opening 52; a locking screw (second locking portion) 54; the elongated hole 56; a front end portion 58; a circuit substrate 60; an LED 62; a light diffusion member 64; an end (first engaging portion) 66; a brush holder 70; the long side axis L.

Claims

1. A power tool having a power unit in a housing, wherein,

the housing includes:

a first housing section;

a second housing section displaceable relative to the first housing section;

an interior access opening for accessing an interior of the housing; and

the fixing mechanism is displaced in a direction away from the first housing section when rotated in a first direction, and is displaced in a direction toward the first housing section when rotated in a second direction opposite to the first direction,

the fixing mechanism is configured to engage with the second casing section in the direction of separation when the fixing mechanism is rotated in the first direction and displaced in the direction of separation from the first casing section, to displace the second casing section in the direction of separation to release the clamping, and to be able to remove the cover from between the first casing section and the second casing section,

the fixing mechanism is configured to engage with the second casing section in the approaching direction when the fixing mechanism is rotated in the second direction and displaced in a direction approaching the first casing section, thereby displacing the second casing section in the approaching direction and sandwiching the cover between the first casing section and the second casing section,

the fixing means is a fixing screw screwed to the first housing portion, and is loosened when rotated in the first direction and tightened when rotated in the second direction,

the second housing portion has a screw head engaging portion arranged to cover a part of a head of the fixing screw, and when the fixing screw is unscrewed by being screwed, the head of the fixing screw is engaged with the screw head engaging portion to displace the second housing portion in the direction away from the screw head,

the screw head engaging portion is formed in an annular shape having a central opening, and the screw rotation operation of the fixing screw can be performed by inserting a tool into the central opening.

2. The power tool according to claim 1,

the second housing part has: an insertion hole through which a shaft portion of the fixing screw is inserted; and a recess connected to the insertion hole and receiving the head,

the screw head snap is configured to retain the head within the recess.

3. The power tool according to claim 1 or 2, wherein,

the first housing portion has a resin-made inner extension portion to which the fixing screw is screwed, and the fixing screw is a self-tapping screw screwed into the inner extension portion.

4. The power tool according to claim 1 or 2, wherein,

the first housing part has a first locking part, the second housing part has a second locking part engaged with the first locking part,

5. The power tool according to claim 4,

the second locking portion is a locking screw screwed to the second housing portion, the first housing portion has an elongated hole for receiving a tip end portion of the locking screw, and an end portion of the elongated hole serves as the first locking portion.

6. The power tool according to claim 1 or 2, wherein,

the power unit is a commutator motor having brushes disposed at a position where the brushes can be replaced through the internal access opening.

7. A power tool having a power unit in a housing, wherein,

the housing is provided with:

a first housing portion;

a second housing section displaceable relative to the first housing section;

an interior access opening for accessing an interior of the housing; and

the first housing portion has a first locking portion, the second housing portion has a second locking portion engaged with the first locking portion,

a displacement range in which the second housing section is displaced in the direction of the separation with respect to the first housing section is restricted by engagement of the first locking section with the second locking section, and the fixing mechanism is not completely detached from the first housing section within the displacement range,