JP2013019277A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To take measures against vibration of an irregular-pitch fan as conventional measures against vibration due to the non-uniform blown air volume of the irregular-pitch fan have been insufficient, whereas use of a so-called irregular-pitch fan as a fan built into a power tool can reduce generation of uncomfortable blade passing noise (NZ noise) peculiar to the fan.SOLUTION: In a handy cleaner 1 having the irregular-pitch fan built-in as a dust attracting fan 30, the dust attracting fan 30 is supported in a body housing 21 via a fan case 24 covered with an elastic cover 23. In addition, by changing a blow-out direction from a radial direction to backward through blow-out ports 24b-24b, air is prevented from directly blowing against the body housing 21 to reduce vibration of a handle 25.

Description

  The present invention relates to a power tool such as a screw tightening tool, a drill for drilling, a hand-held small vacuum cleaner (handy cleaner), a dust collector, or the like, which is equipped with an electric motor as a drive source.

  For example, an electric tool such as the screw tightener includes a fan for mainly cooling a motor that is rotated by an electric motor as a drive source. The handy cleaner includes a suction force generating fan that is rotated by an electric motor. Fans built in these power tools cause vibration and noise due to their rotation, and therefore, a device for reducing them has been conventionally used. Patent Documents 1-4 listed below disclose techniques for reducing noise and vibration related to this type of fan. In particular, Patent Document 1-2 discloses a technique for reducing noise such as wind noise using a so-called unequal pitch fan. This unequal pitch fan is one in which the mounting angles (positions and intervals around the rotation axis) of each blade are unevenly arranged according to a certain standard such as a so-called golden angle, for example, to reduce unpleasant noise such as NZ sound. Can do. The “NZ sound” means a narrow band sound having a frequency of NZ / 60 [Hz] (N: fan rotation speed [1 / min], Z: blade number).

JP 2010-144530 A Utility Model Registration No. 3148914 Japanese Patent No. 3071977 Japanese Patent No. 3460350 JP2003-111698A

However, the conventional unequal pitch fan or a power tool having the unequal pitch has a problem in that the air flow unevenness occurs due to the unequal pitch of the blades, and this air flow unevenness causes vibration.
An object of the present invention is to reduce vibration of an unequal pitch fan built in a power tool, for example.

The above problems are solved by the following invention.
A first invention is a power tool including a centrifugal fan type unequal pitch fan that blows wind in all radial directions, unlike a pitch of at least one of a plurality of blade pitches. And a fan case that houses the unequal pitch fan, and vibration caused by uneven air volume of the unequal pitch fan between the fan case and a handle portion that is provided on a main body housing and is gripped by a user. It is the power tool which provided the vibrational absorption part for absorbing.
According to the first aspect of the invention, the omnidirectional blowing type unequal pitch fan is installed as a motor cooling fan or a dust suction fan, whereby generation of an uncomfortable blade passing sound (so-called NZ sound) or the like can be suppressed. Therefore, it is possible to reduce the noise of a power tool such as a handy cleaner in which this is installed as a dust suction fan. In addition, vibrations caused by unevenness in the blown air volume are suppressed from being absorbed through the vibration absorbing portion and transmitted to the handle portion, so that the user is less affected by the hand holding the handle portion. Thus, the usability of the power tool can be improved.
A second invention is a power tool according to the first invention, wherein the fan case is covered with an elastic cover as the vibration absorbing portion, and the fan case is supported on the main body housing via the elastic cover.
According to the second invention, the vibration generated by the unequal pitch fan is reduced by the elastic cover as the vibration absorbing portion and transmitted to the main body housing and the handle portion, thereby reducing the vibration of the power tool. To improve its usability.
According to a third invention, in the first or second invention, the radiating direction of the unequal pitch fan is shielded by the fan case, and the blowing direction of the wind is changed from the radiating direction to the axial direction so that the wind is directly applied to the main body housing. It is a power tool that does not blow.
According to the third invention, the blowing direction of the wind of the unequal pitch fan, which is a centrifugal fan, is converted from the radial direction to the axial direction by the fan case, so that it does not blow directly to the main body housing located in the radial direction. It is possible to suppress the vibration generated due to the uneven air volume of the unequal pitch fan from being transmitted to the main body housing. For this reason, the fan case functions as a vibration absorber. Since the vibration of the main body housing is suppressed by the fan case as the vibration absorbing portion, the vibration of the user's hand holding the handle portion is reduced and the usability of the power tool can be improved.

It is an internal side view of the handy cleaner which equipped the fan which concerns on embodiment of this invention. It is a front view of a dust suction fan. This figure has shown the state which removed the shielding board (shroud). It is a perspective view of a dust suction fan. This figure has shown the state which removed the shielding board. It is a longitudinal cross-sectional view of a dust suction fan, Comprising: It is an expanded view of a blade | wing.

Next, an embodiment of the present invention will be described with reference to FIGS. In the embodiment described below, a handy cleaner 1 is illustrated as a power tool. The present embodiment is characterized by a dust suction fan 30 built in the handy cleaner 1. Since the basic configuration of the handy cleaner 1 does not require any change, it will be briefly described below.
The handy cleaner 1 includes a front dust collecting case 10 and a rear main body 20. A dust suction nozzle 11 is provided at the front end of the dust suction case 10. The dust is sucked into the dust suction case 10 through the dust suction nozzle 11. A dust suction filter 12 is disposed behind the dust suction nozzle 11. The dust filter 12 is mounted in a state of being covered with a filter frame 13 attached to the front portion of the main body portion 20, and is provided in a state of protruding from the front portion of the main body portion 20 into the dust absorption case 10. The dust filter 12 prevents the dust in the dust case 10 from entering the main body 20 side. By separating the dust-absorbing case 10 from the main body 20, the dust absorbed in the dust-absorbing case 10 can be discarded.
The main body portion 20 is a mechanism portion that generates a dust suction force in the dust suction case 10, and has a configuration in which an electric motor 22 as a drive source and a dust suction fan 30 that is rotated by the electric motor 22 are incorporated in the main body housing 21. . The dust-absorbing fan 30 is housed in the front portion of the main body 20 via a cylindrical fan case 24. A vibration absorbing elastic cover 23 is coated on the peripheral wall 24d of the fan case 24, in particular. The fan case 24 is supported by the main body housing 21 of the main body 20 via the elastic cover 23. In this embodiment, a rubber cover is used as the elastic cover 23, and this functions as a vibration absorbing portion. An electric motor 22 is attached to the rear base 24c of the fan case 24.

The dust suction fan 30 is an omnidirectional blow-out centrifugal fan. The front side of the fan case 24 communicates with the inside of the dust filter 12 through an air inlet 24a provided at the center thereof. The airflow generated by the rotation of the dust suction fan 30 is blown against the peripheral wall portion 24d of the fan case 24 to convert the flow backward, and the blowout ports 24b to 24b provided on the rear base portion 24c of the fan case 24 are converted. By blowing backward through the air outlet 24b, a wind flow (dust absorption force) for dust absorption is generated through the air inlet 24a. When the dust absorption force acts in the dust suction case 10 via the dust suction filter 12, dust is sucked into the dust suction case 10 via the dust suction nozzle 11. Further, the wind generated by the rotation of the dust suction fan 30 that is a centrifugal fan is blown rearward through the blowout ports 24 b to 24 b provided on the rear surface of the fan case 24, so that it does not blow directly to the main body housing 21. In this respect as well, the vibration of the main body housing 21 due to the air flow unevenness is suppressed.
A loop-shaped handle portion 25 that is gripped by the user is integrally provided on the upper portion of the main body housing 21. A trigger-type switch lever 28 that is pulled by the user with a fingertip is provided at the inner peripheral front portion of the handle portion 25. When the switch lever 28 is pulled (turned on) with the fingertip of the hand holding the handle portion 25, the main switch 29 is turned on and the electric motor 22 is activated. When the switch lever 28 is turned on, the LED light provided at the front portion of the handle portion 25 is turned on, and the vicinity of the tip of the dust suction nozzle 11 is illuminated brightly.
A battery pack 26 as a power source is attached to the rear surface of the main body portion 20 and the lower surface of the handle portion 25. The battery pack 26 is, for example, a 14.4 V lithium-ion battery, and a battery widely used as a power source for mainly hand-held power tools such as screw tightening tools and cutting machines can be used. The battery pack 26 can be repeatedly used by being removed from the battery mounting portion 27 of the slide mounting type and charged by a separately prepared charger.

The above-described dust suction fan 30 is mainly devised for noise reduction. The dust suction fan 30 is a so-called unequal pitch fan. In general, an unequal pitch fan can suppress generation of an unpleasant blade passing sound called a keen specific to the fan because the blade passing cycle is irregular. The dust suction fan 30 includes a circular substrate (disk) 31 fixed to the output shaft of the electric motor 22, and an annular shielding plate 32 disposed substantially parallel to the substrate 31 at a predetermined interval. A plurality of blades 33 to 33 arranged at unequal pitches are provided between the shielding plate 32 and the substrate 31. The air inlet 24 a of the fan case 24 is aligned with the air inlet 32 a in the center of the shielding plate 32. The dust suction fan 30 with the shielding plate 32 removed is shown in FIG.
A plurality of blades 33 to 33 are formed integrally with the substrate 31. Each blade 33 extends along the spiral path in the radial direction from the vicinity of the center (rotation center J) of the substrate 31. The inner peripheral side proximal end portion of each blade 33 is located on substantially the same circumference with the rotation center J as the center, and the circumferential interval between the inner peripheral proximal ends of the adjacent blades 33 and 33 ( The pitch: angle θ) is not constant and varies at irregular angular intervals in the circumferential direction. However, the curvatures of the blades 33 to 33 are generally aligned. For this reason, the space | interval between the outer peripheral side edge parts of the blade | wings 33 and 33 adjacent to the circumferential direction is not constant, but is non-uniform | heterogenous.

As shown in FIG. 4, the range of the blades 33 on the inner peripheral end side and projecting into the intake holes 32 a of the shielding plate 32 gradually decreases as the height dimension from the substrate 31 reaches the inner peripheral side. It is inclined in the direction. Hereinafter, the inclination range in which the height changes is referred to as an inducer 33a of the blade 33. Between the board | substrate 31 and the shielding board 32, the height dimension from the board | substrate 31 of each blade | wing 33 is substantially constant. Hereinafter, a range in which the height is substantially constant is referred to as a main body portion 33 b of the blade 33. The flow of wind generated by the rotation of the dust suction fan 30 is directed outward in the radial direction through the air inlet 24 a and the air inlet 32 a of the shielding plate 32. From this, the wind inlet of each blade 33 is largely opened by the inducer 33a, and thereby the flow of wind flowing between the blades 33 and 33 through the intake hole 32a can be made smooth.
In FIG. 4, the shape of the inducer 33 a of each blade 33 is different as indicated by a solid line and a two-dot chain line. The surface areas of the inducers 33a are different from each other by appropriately changing the shapes of the inducers 33a. By changing the size or surface area of the inducer 33a, the amount of air flowing into the main body 33b of each blade 33 can be controlled. The larger the size or surface area of the inducer 33a, the greater the amount of air taken. On the other hand, the larger the interval θ between the adjacent blades 33, 33, the larger the blown-out air volume. As a result, there is a possibility that vibrations may occur due to non-uniformity in the blown-out air volume (uneven air volume).
For this reason, in a portion where the interval θ between the blades 33, 33 is large, the surface area of the inducers 33a, 33a is reduced to suppress the amount of air to be taken in, so that the air is blown out radially between the main body portions 33b, 33b. By suppressing the air volume, the air volume unevenness can be reduced or eliminated as a whole of the dust suction fan 30. As described above, in the present embodiment, as a countermeasure against the vibration caused by the airflow unevenness, the airflow unevenness due to the nonuniformity (unequal pitch) of the interval θ is offset by appropriately changing the shape or the surface area of the inducers 33a to 33a. As a result, vibration is reduced.

According to the dust suction fan 30 according to the present embodiment configured as described above, since a so-called unequal pitch fan is used as the dust suction fan 30, unpleasant noise such as NZ noise can be reduced.
A dust suction fan 30 is accommodated in the fan case 24, and the surface of the fan case 24 is covered with an elastic cover 23 as a vibration absorbing portion. The dust suction fan 30 is supported by the main body housing 21 through the elastic cover 23. For this reason, the vibration generated due to the dust suction fan 30 being an unequal pitch fan is suppressed from being absorbed by the elastic cover 23 and transmitted to the main body housing 21, thereby the user holding the handle portion 25. Therefore, it is possible to improve the usability of the handy cleaner 1 by reducing the vibration transmitted to the hand.
Further, the blowing direction of the wind of the dust suction fan 30 which is a centrifugal fan is converted by the fan case 24 from the radial direction to the rear in the axial direction through the blowing ports 24b to 24b. For this reason, the wind generated by the dust suction fan 30 is not directly blown onto the main body housing 21, thereby making it difficult for vibration caused by the air volume unevenness to be transmitted to the main body housing 21. As described above, the fan case 24 (particularly, the peripheral wall portion 24d) serving as the vibration absorbing portion absorbs the vibration caused by the air volume unevenness and does not transmit to the main body housing 21, so that the user who holds the handle portion 25 The vibration received by the hand can be suppressed, and the usability of the handy cleaner 1 can also be improved in this respect.
In addition, the unevenness (variation) of the blown air flow due to the unequal pitch fan is corrected or reduced by appropriately changing the surface area of the inducer 33a of each blade 33, thereby making the blown air flow uniform. Therefore, the vibration of the dust suction fan 30 itself can be reduced.

Various modifications can be made to the embodiment described above. For example, the blowing direction is changed by the elastic cover 23 and mainly the peripheral wall portion 24d of the fan case 24 as a vibration absorbing portion for absorbing vibration generated due to the air flow unevenness in the dust suction fan 30 which is an unequal pitch fan. Although the configuration is illustrated, instead of the elastic cover, for example, a sponge may be attached to the outer surface of the peripheral wall portion 24d or a brushing process may be performed to absorb vibration.
Further, instead of the peripheral wall portion 24d of the fan case 24, an equivalent peripheral wall portion as a vibration absorbing portion is provided on the main body housing 21 side via an elastic member, so that the air blown from the dust suction fan in the radial direction is directly It is good also as a structure which does not spray on the housing 21. FIG.
Furthermore, as a vibration absorbing part interposed between the handle part 25 and the dust suction fan 30, a structure having a handle floating structure (anti-vibration handle) for supporting the handle part 25 on the main body housing via an elastic member, A structure with a double structure, a structure in which a plurality of dust suction fans are connected in the axial direction to balance the air volume by shifting the phase, a structure in which the dust suction fan and the fan case are supported on the main body housing side via an electric motor, or These can be applied in appropriate combination. By providing these various forms of vibration absorbers, it is possible to make it difficult for vibration caused by uneven air flow of the unequal pitch fan to be transmitted to the handle part 25.
Further, as a measure for correcting or reducing the air flow unevenness caused by being an unequal pitch fan (air flow unevenness reducing measure M), the size or surface area of the inducer 33a is appropriately changed as illustrated above. In addition to this, for example, the thickness of each blade 33 is changed, or the so-called skew angle of the blade 33 (the angle of the blade 33 with respect to the substrate 31) is changed, and further, the turning angle of the blades 33 to 33 with respect to the radial direction However, the amount of blown air between the blades 33 and 33 is also nonuniform by changing the inclination with respect to the radial direction (the position in the substrate surface direction with respect to the radial direction passing through the blade base end (fan start point) in a plan view). Thus, the air flow unevenness can be canceled out, and vibration can be reduced.
Further, although the dust suction fan 30 of the handy cleaner 1 is illustrated as a power tool, the various exemplified airflow non-uniformity correction measures M are incorporated in other power tools such as a motor cooling fan or a blower fan such as a dust collector and an engine blower. The same applies to fans.

1 ... Handy cleaner (power tool)
2 ... LED light 10 ... Dust-absorbing case 11 ... Dust-absorbing nozzle 12 ... Dust-absorbing filter 13 ... Filter frame 20 ... Main body 21 ... Main body housing 22 ... Electric motor 23 ... Elastic cover 24 ... Fan case 24a ... Intake port, 24b ... Outlet port, 24c ... Rear base portion 24d ... Surrounding wall portion 25 ... Handle portion 26 ... Battery pack 27 ... Battery mounting portion 28 ... Switch lever 29 ... Main switch 30 ... Dust-absorbing fan 31 ... Substrate (disc)
32 ... Shield plate (shroud), 32a ... Intake hole 33 ... Blade, 33a ... Inducer, 33b ... Main body M ... Air flow unevenness correction measure J ... Fan rotation center

Claims (3)

Unlike the other pitches, at least one of the pitches of the plurality of blades is a power tool equipped with an unequal pitch fan that blows wind in all radial directions,
A fan case that includes the unequal pitch fan is provided, and vibration caused by uneven air volume of the unequal pitch fan is provided between the fan case and a handle portion that is held by a user provided in the main body housing. A power tool provided with a vibration absorbing part for absorbing. The power tool according to claim 1, wherein as the vibration absorbing portion, the fan case is covered with an elastic cover, and the fan case is supported on the main body housing via the elastic cover. 3. The power tool according to claim 1, wherein a radial direction of the unequal pitch fan is shielded by the fan case and a wind blowing direction is changed from the radial direction to an axial direction so that the wind is a main body housing. A power tool that prevents direct contact with the power tool.

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