US20230302601A1 - Portable electric tool - Google Patents

Portable electric tool Download PDF

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Publication number
US20230302601A1
US20230302601A1 US18/177,301 US202318177301A US2023302601A1 US 20230302601 A1 US20230302601 A1 US 20230302601A1 US 202318177301 A US202318177301 A US 202318177301A US 2023302601 A1 US2023302601 A1 US 2023302601A1
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United States
Prior art keywords
weight
dust collection
output shaft
fan
cooling fan
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
US18/177,301
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English (en)
Inventor
Fumihide Sugita
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Makita Corp
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Makita Corp
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Assigned to MAKITA CORPORATION reassignment MAKITA CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: Sugita, Fumihide
Publication of US20230302601A1 publication Critical patent/US20230302601A1/en
Pending legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
    • B24B23/02—Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
    • B24B23/04—Portable grinding machines, e.g. hand-guided; Accessories therefor with oscillating grinding tools; Accessories therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
    • B24B23/005—Auxiliary devices used in connection with portable grinding machines, e.g. holders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/007—Weight compensation; Temperature compensation; Vibration damping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B55/00—Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B55/00—Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition
    • B24B55/06—Dust extraction equipment on grinding or polishing machines
    • B24B55/10—Dust extraction equipment on grinding or polishing machines specially designed for portable grinding machines, e.g. hand-guided
    • B24B55/102—Dust extraction equipment on grinding or polishing machines specially designed for portable grinding machines, e.g. hand-guided with rotating tools

Definitions

  • the present invention relates to a portable electric tool.
  • orbital sanders As portable electric tools, orbital sanders have been known conventionally.
  • the orbital sanders cause a pad coupled at one end of an output shaft (for example, a motor shaft) to perform an eccentric circular motion (an orbital motion).
  • Sanding paper is attached to the pad.
  • a sanding/abrading operation can be performed by pressing the sanding paper against a processing target.
  • Japanese Patent Application Public Disclosure No. 2013-188804 discloses a fan attached to an output shaft and including two thick portions that function as weights. This fan has a function as a dust collection fan and a function as a motor cooling fan.
  • the present disclosure discloses a portable electric tool.
  • This portable electric tool may include an output shaft, a tool accessory, a dust collection fan, a motor, a motor cooling fan, a first weight, and a second weight.
  • the output shaft may extend in an axial direction and be rotatable.
  • the tool accessory may be configured to perform an eccentric circular motion according to the rotation of the output shaft.
  • the dust collection fan may be fixed to the output shaft so as to circumferentially surround the output shaft.
  • the motor may be disposed on an opposite side of the dust collection fan from the tool accessory in the axial direction and be configured to provide a rotational driving force to the output shaft.
  • the motor cooling fan may be disposed between the dust collection fan and the motor in the axial direction.
  • the first weight may be attached to one of the dust collection fan and the motor cooling fan and may have a specific gravity higher than the one of the fans.
  • the second weight may be disposed at a position different from the first weight in the axial direction.
  • the first weight and the second weight are disposed at axially different positions, and therefore centrifugal forces respectively applied to the first weight and the second weight can be prevented from being canceled out by each other. Therefore, the masses of the first weight and the second weight required to solve a couple unbalance can be reduced.
  • a large difference in specific gravity can be secured between the first weight and the one of the fans (the dust collection fan or the motor cooling fan) to which the first weight is attached, and the centrifugal force required to solve the couple unbalance can be efficiently generated. Therefore, the size of the first weight can be reduced. Furthermore, the weight of the one of the fans to which the first weight is attached can be reduced.
  • FIG. 1 is a perspective view of a sander according to a first embodiment.
  • FIG. 2 is a left side view of the sander.
  • FIG. 3 is a plan view of the sander.
  • FIG. 4 is a cross-sectional view taken along a line A-A illustrated in FIG. 3 .
  • FIG. 5 is a partial enlarged view of FIG. 4 .
  • FIG. 6 is a partial cross-sectional view taken along a line B-B illustrated in FIG. 3 .
  • FIG. 7 is a perspective view of the sander with a part of components removed therefrom.
  • FIG. 8 is a perspective view of a dust collection fan, a motor cooling fan, a first weight, and a second weight.
  • FIG. 9 is a perspective view of the dust collection fan, the motor cooling fan, the first weight, and the second weight.
  • FIG. 10 is a perspective view of the dust collection fan, the motor cooling fan, the first weight, and the second weight.
  • FIG. 11 is a schematic view illustrating a layout of the first weight and the second weight according to a second embodiment.
  • FIG. 12 is a schematic view illustrating a layout of the first weight and the second weight according to a third embodiment.
  • FIG. 13 is a schematic view illustrating a layout of the first weight and the second weight according to a fourth embodiment.
  • the first weight and the second weight may be disposed so as to be spaced apart from each other in the axial direction via a spacer. According to this configuration, a great distance can be secured between the first weight and the second weight in the axial direction due to the spacer. Therefore, the masses of the first weight and the second weight required to solve the couple unbalance can be further reduced.
  • the dust collection fan and the motor cooling fan may be disposed so as to be spaced apart from each other in the axial direction. This configuration allows the motor cooling fan to be disposed closer to the motor. Therefore, the motor cooling performance by the motor cooling fan can be improved.
  • the dust collection fan and the motor cooling fan may be disposed so as to be spaced apart from each other in the axial direction via the spacer. According to this configuration, the dust collection fan and the motor cooling fan can be spaced apart from each other by a great distance. Therefore, the motor cooling fan can be located further closer to the motor and the motor cooling performance can be further improved.
  • the first weight may be attached to the dust collection fan and may have a specific gravity higher than the dust collection fan.
  • the motor cooling fan may be fixed to the output shaft so as to circumferentially surround the output shaft.
  • the second weight may be attached to the motor cooling fan and may have a specific gravity higher than the motor cooling fan.
  • the dust collection fan may be made from light metal.
  • the first weight may be made from heavy metal. According to this configuration, the masses of the dust collection fan and the first weight can be optimized. In other words, the weight of the dust collection fan can be reduced, and the weight and the size of the first weight can also be reduced while the function of the first weight is maintained.
  • the first weight may be attached to the dust collection fan by screwing. This configuration facilitates mounting of the first weight and the dust collection fan onto the output shaft.
  • the motor cooling fan may be made from synthetic resin.
  • the second weight may be made from metal. According to this configuration, the masses of the motor cooling fan and the second weight can be optimized. In other words, the weight of the motor cooling fan can be reduced, and the weight and the size of the second weight can also be reduced while the function of the second weight is maintained.
  • the second weight may include a through-hole through which the output shaft extends. According to this configuration, the second weight can be radially positioned with high accuracy. Further, the motor cooling fan is prevented from being deformed due to the centrifugal force applied to the second weight even when the motor cooling fan is made from synthetic resin.
  • the first weight may include a through-hole through which the output shaft extends. According to this configuration, the first weight can be radially positioned relative to the output shaft with high accuracy.
  • the spacer may be in the form of a first bearing rotatably supporting the output shaft.
  • the bearing originally required to rotatably support the output shaft can be utilized as the spacer, and therefore eliminates the necessity of disposing a spacer additionally. Therefore, the size of the portable electric tool can be reduced and the manufacturing cost can be cut down.
  • the dust collection fan, the motor cooling fan, the first weight, and the second weight may be fixed to the motor shaft by fastening them together. According to this configuration, the manufacturing process can be simplified.
  • the dust collection fan may include a shaft portion extending in the axial direction toward an opposite side from the output shaft and disposed eccentrically with respect to the output shaft.
  • the tool accessory may be fixed to the shaft portion via a second bearing rotatably supporting the shaft portion. According to this configuration, an eccentric circular motion of the tool accessory can be achieved with a simple configuration.
  • an orbital sander (hereinafter simply referred to as a sander) 10 as one exemplary embodiment will be described in further detail with reference to the drawings.
  • the sander 10 exemplarily cited in the present embodiment is also called a finishing sander.
  • the sander 10 includes an electric motor 60 , a motor shaft 61 , and a tool accessory (a sanding/polishing part) 30 .
  • One end of the motor shaft 61 is coupled with the tool accessory 30 via another member.
  • the sander 10 is configured in such a manner that the tool accessory 30 performs a processing (sanding, polishing, abrading, etc.) motion by a rotation of the electric motor 60 (the motor shaft 61 ).
  • a direction in which the motor shaft 61 extends is defined to be a vertical direction of the sander 10 .
  • One side in the vertical direction on which the tool accessory 30 is located is defined to be a lower side, and the opposite side therefrom is defined to be an upper side.
  • the longitudinal direction of the sander 10 perpendicular to the vertical direction is defined to be a front-rear direction of the sander 10 .
  • One side in the front-rear direction on which the tool accessory 30 is located is defined to be a front side, and the opposite side therefrom is defined to be a rear side.
  • a direction perpendicular to the front-rear direction and the vertical direction is defined to be a left-right direction of the sander 10 .
  • a right side in the left-right direction when the front side is viewed from the rear side is defined to be a right side of the sander 10
  • the opposite side therefrom is defined to be a left side of the sander 10 .
  • the sander 10 includes a housing 20 .
  • the housing 20 includes a front housing portion 21 , a grip portion 22 , and a rear housing portion 23 .
  • the front housing portion 21 and the rear housing portion 23 are coupled in the front-rear direction via a vertically separated forked form, and an upper-side coupling portion functions as the grip portion 22 .
  • a power source cord 26 extends out of the rear edge of the rear housing portion 23 .
  • the power source cord 26 is used to supply a commercial alternating-current power source to the electric motor 60 .
  • the power source of the electric motor 60 may be a battery detachably mounted on the sander 10 instead of the commercial power source.
  • a controller 65 is contained in the lower portion of the rear housing portion 23 .
  • the controller 65 is electrically connected to the power source cord 26 and the electric motor 60 , and controls the operation of the electric motor 60 by controlling power that is supplied to the electric motor 60 .
  • a switch 27 is provided at the front portion of the front housing portion 21 . The switch 27 is used to perform an operation of starting up and stopping the electric motor 60 .
  • the switch 27 is electrically connected to the controller 65 .
  • the electric motor 60 is contained in the front housing portion 21 .
  • the motor shaft 61 of the electric motor 60 extends vertically, and is rotatably supported by bearings 62 and 63 fixed to the front housing portion 21 .
  • the bearing 62 supports the upper end of the motor shaft 61
  • the bearing 63 supports the vicinity of the lower end of the motor shaft 61 .
  • a motor cooling fan 40 is disposed below the electric motor 60 .
  • the motor cooling fan 40 is fixed to the motor shaft 61 so as to circumferentially surround the motor shaft 61 (the fixation method therefor will be described below).
  • air is introduced into the housing 20 from outside via intake ports 24 formed on the front housing portion 21 and the grip portion 22 (refer to FIGS. 1 and 2 ).
  • This air passes through the electric motor 60 and flows axially (the direction in which the motor shaft 61 extends), is directed radially outward at the motor cooling fan 40 , and is exhausted out of the housing 20 via an exhaust port 25 formed on the front housing portion 21 (refer to FIGS. 1 and 2 ).
  • the electric motor 60 is cooled with the aid of such an air flow.
  • a dust collection fan 50 is disposed below the motor cooling fan 40 .
  • the dust collection fan 50 and the motor cooling fan 40 are axially spaced apart from each other via the bearing 63 .
  • the layout of the motor cooling can 40 and the dust collection fan 50 axially spaced apart from each other allows the motor cooling fan 40 and the electric motor 60 to be located closer to each other. Therefore, the motor cooling performance can be improved.
  • the dust collection fan 50 is fixed to the lower end of the motor shaft 61 so as to circumferentially surround the motor shaft 61 (the fixation method therefor will be described below).
  • the dust collection fan 50 includes a generally disk-shaped face plate 51 , a shaft portion 52 , and a plurality of blades 53 .
  • the shaft portion 52 protrudes cylindrically downward from the face plate 51 at around the center of the face plate 51 .
  • a hole 54 is formed inside the shaft portion 52 .
  • the plurality of blades 53 radially extends on the radially outer side with respect to the shaft portion 52 on the lower surface of the face plate 51 .
  • a shaft insertion hole 55 is formed on the face plate 51 so as to be in communication with the hole 54 .
  • the shaft insertion hole 55 has an inner diameter larger than the hole 54 .
  • the dust collection fan 50 is fixed to the motor shaft 61 in a state that the lower end of the motor shaft 61 is inserted in the shaft insertion hole 55 .
  • the hole 54 of the shaft portion 52 is coaxial with the motor shaft 61 , but the shaft portion 52 is eccentric with respect to the motor shaft 61 .
  • the shaft portion 52 is rotatably supported by a bearing 64 . Therefore, the bearing 64 is eccentric with respect to the motor shaft 61 .
  • a space containing the dust collection fan 50 is in communication with a dust collection passage 28 extending in the front-rear direction in the lower portion of the rear housing portion 23 .
  • a dust collection bag 29 is detachably mounted at the rear edge portion of the rear housing portion 23 . When the dust collection bag 29 is mounted, the dust collection passage 28 and the inside of the dust collection bag 29 are in communication with each other.
  • the tool accessory 30 is located at the lowermost portion of the sander 10 , and includes a pad 31 and a base 32 disposed above the pad 31 .
  • the pad 31 and the base 32 each have a generally triangular shape pointed on the front side thereof as viewed vertically.
  • the pad 31 and the base 32 are coupled via a vertically extending bolt 33 .
  • a plurality of through-holes 34 which extends through the pad 31 vertically, is formed on the bottom surface of the pad 31 (only one through-hole 34 is visible in the cross-section illustrated in FIG. 5 ).
  • a space 35 which is in communication with the through-holes 34 , is generated between the pad 31 and the base 32 .
  • This space 35 is in communication with the dust collection passage 28 .
  • Sanding paper (not illustrated) is attached to the bottom surface of the pad 31 . Holes are formed on this sanding paper at positions corresponding to the through-holes 34 of the pad 31 .
  • the bearing 64 which supports the shaft portion 52 of the dust collection fan 50 , is fixed to the tool accessory 30 . Therefore, the tool accessory 30 is coupled with the motor shaft 61 via the bearing 64 and the dust collection fan 50 . Further, as illustrated in FIGS. 5 to 7 , the tool accessory 30 is further coupled with the front housing portion 21 via a vertically extending connector 70 . As illustrated in FIG. 7 , the connector 70 is disposed on each of the front portion and the rear portion of the front housing portion 21 .
  • each of the connectors 70 includes six foot portions 71 , an upper plate portion 75 , and a lower plate portion 76 (the number of foot portions 71 is 12 in total).
  • the foot portions 71 , the upper plate portion 75 , and the lower plate portion 76 are joined as an integrally molded member made from a single material, and the material thereof is TPE (thermoplastic elastomer).
  • the upper plate portion 75 and the lower plate portion 76 each have a rectangular shape elongated in the left-right direction and flat in the vertical direction, and the foot portion 71 has a generally columnar shape extending vertically.
  • the foot portions 71 are unevenly distributed with three of them located for each of the left and right edge portions.
  • the six foot portions 71 are lined up in a row.
  • Each of the foot portions 71 includes a top portion 72 , a bottom portion 73 , and an intermediate portion 74 .
  • the top portion 72 and the bottom portion 73 are conically shaped, and the intermediate portion 74 is columnarly shaped.
  • the upper plate portion 75 is immovably held on the front housing portion 21 .
  • the lower plate portion 76 is immovably held on the base 32 .
  • the above-described sander 10 operates in the following manner.
  • the motor shaft 61 starts a rotation.
  • the bearing 64 coupling the motor shaft 61 and the tool accessory 30 , and the shaft portion 52 of the dust collection fan 50 are eccentric with respect to the motor shaft 61 as described above. Therefore, when the motor shaft 61 is rotated, the tool accessory 30 performs an eccentric circular motion (an orbital motion) while changing horizontal relative positions of the top portion 72 and the bottom portion 73 of each of the foot portions 71 .
  • each of the intermediate portions 74 is placed in an inclined posture connecting the top portion 72 and the bottom portion 73 .
  • the inclination direction of the intermediate portion 74 is also rotated while being deformed.
  • the tool accessory 30 is moved so as to draw a circle along a horizontal surface while keeping this posture without being rotated itself.
  • the processing sanding, polishing, abrading, etc.
  • the dust collection fan 50 includes the eccentric shaft portion 52 and the shaft portion 52 is supported by the bearing 64 , by which an eccentric circular motion can be achieved with a simple configuration.
  • the sander 10 includes a configuration for solving a static unbalance and a couple unbalance with the aid of counterweights (a first weight 80 and a second weight 90 ), thereby reducing the vibration.
  • a configuration for solving a static unbalance and a couple unbalance with the aid of counterweights (a first weight 80 and a second weight 90 ), thereby reducing the vibration.
  • the first weight 80 is attached to the dust collection fan 50 .
  • the first weight 80 is generally shaped like a semi-circular plate, and includes an annular portion 81 at the center of the circular arc thereof.
  • the annular portion 81 includes a shaft through-hole 82 , through which the motor shaft 61 extends. Therefore, the first weight 80 can be radially positioned relative to the motor shaft 61 with high accuracy.
  • annular portion 56 is formed around the shaft insertion hole 55 of the dust collection fan 50 .
  • the annular portion 56 annularly protrudes from the face plate 51 upward.
  • the annular portion 56 is fitted inside the annular portion 81 in a state that the first weight 80 is attached to the dust collection fan 50 .
  • the first weight 80 can be radially positioned relative to the dust collection fan 50 with high accuracy.
  • the face plate 51 of the dust collection fan 50 has such a shape that approximately a half of the outer edge portion thereof is bent upward along the circumferential direction.
  • This bent portion corresponds to a portion where the first weight 80 is not attached. Therefore, as illustrated in FIG. 8 , the both circumferential edge portions of the bent portion and the diametrically extending end surface of the first weight 80 are in abutment with each other in the state that the first weight 80 is attached to the dust collection fan 50 . Therefore, the first weight 80 can be circumferentially positioned relative to the dust collection fan 50 with high accuracy.
  • the first weight 80 is attached to the dust collection fan 50 by threadably engaging a screw 58 (refer to FIG. 5 ) with a screw hole 57 of the dust collection fan 50 and a screw hole 83 of the first weight 80 (refer to FIG. 10 ).
  • a screw 58 (refer to FIG. 5 ) with a screw hole 57 of the dust collection fan 50 and a screw hole 83 of the first weight 80 (refer to FIG. 10 ).
  • This facilitates the mounting of the first weight 80 and the dust collection fan 50 onto the motor shaft 61 .
  • the first weight 80 and the dust collection fan 50 may be individual separate members until they are eventually mounted on the motor shaft 61 .
  • the materials of the first weight 80 and the dust collection fan 50 are selected in such a manner that the first weight 80 has a specific gravity higher than the specific gravity of the dust collection fan 50 .
  • a centrifugal force required to solve the couple unbalance can be efficiently generated by securing a difference in specific gravity between the first weight 80 and the dust collection fan 50 . In other words, the mass of the first weight 80 can be reduced.
  • the dust collection fan 50 is made from light metal (for example, aluminum, magnesium, titan, or an alloy containing any of them). Therefore, the weight of the dust collection fan 50 can be reduced as much as possible while the strength required for the dust collection fan 50 , which is subjected to the load of the tool accessory 30 , is ensured.
  • the first weight 80 is made from heavy metal (for example, iron, zinc, copper, or an alloy containing any of them (for example, yellow brass)). According to this configuration, a large difference in specific gravity can be secured between the first weight 80 and the dust collection fan 50 , and the centrifugal force required to solve the couple unbalance can be extremely efficiently generated. This leads to reductions in the weight and the size of the first weight 80 .
  • the materials of the first weight 80 and the dust collection fan 50 can be selected in any manner as long as the specific gravity of the first weight 80 is higher than the specific gravity of the dust collection fan 50 .
  • the second weight 90 is attached to the motor cooling fan 40 .
  • the motor cooling fan 40 and the second weight 90 are individual separate members in the present embodiment, but, as long as the motor cooling fan 40 and the second weight 90 are kept in contact with each other inseparably in a state that the motor cooling fan 40 and the second weight 90 are eventually mounted on the motor shaft 61 , such a contact state is intended to be included in the state that the second weight 90 is attached to the motor cooling fan 40 herein.
  • the second weight 90 is shaped like a circular sector, and includes an annular portion 91 at the center of the circular arc thereof.
  • the annular portion 91 includes a shaft through-hole 92 , through which the motor shaft 61 extends. Therefore, the second weight 90 can be radially positioned relative to the motor shaft 61 with high accuracy.
  • the second weight 90 is disposed at a position opposite from the first weight 80 with the motor shaft 61 interposed therebetween as viewed axially.
  • the motor cooling fan 40 includes a generally partial disk-shaped face plate 41 , a plurality of blades 42 , and a proximal portion 44 .
  • a shaft through-hole 43 through which the motor shaft 61 extends, is formed at the center of the circular arc of the face plate 41 .
  • the proximal portion 44 protrudes in a circular arc form from the face plate 41 upward on the radially outer side with respect to the shaft through-hole 43 .
  • the plurality of blades 42 radially extends from the proximal portion 44 radially outward on the upper surface of the face plate 41 .
  • the proximal portion 44 has a shape in conformity with the annular portion 91 of the second weight 90 . Therefore, the second weight 90 can be radially positioned relative to the motor cooling fan 40 with high accuracy. Further, as illustrated in FIGS. 8 and 9 , the both circumferential edge portions of the proximal portion 44 of the motor cooling fan 40 and the both circumferential edge portions of the second weight 90 are in abutment with each other in the state that the second weight 90 is attached to the motor cooling fan 40 . Therefore, the second weight 90 can be circumferentially positioned relative to the motor cooling fan 40 with high accuracy.
  • the materials of the second weight 90 and the motor cooling fan 40 are selected in such a manner that the second weight 90 has a specific gravity higher than the specific gravity of the motor cooling fan 40 .
  • a centrifugal force required to solve the couple unbalance can be efficiently generated by securing a difference in specific gravity between the second weight 90 and the motor cooling fan 40 . In other words, the mass of the second weight 90 can be reduced.
  • the motor cooling fan 40 is made from synthetic resin. Therefore, the weight of the motor cooling fan 40 can be reduced.
  • the second weight 90 is made from metal.
  • the second weight 90 may be made from heavy metal similarly to the first weight 80 . According to this configuration, a large difference in specific gravity can be secured between the second weight 90 and the motor cooling fan 40 , and the centrifugal force required to solve the couple unbalance can be extremely efficiently generated. This leads to reductions in the weight and the size of the second weight 90 .
  • the materials of the second weight 90 and the motor cooling fan 40 can be selected in any manner as long as the specific gravity of the second weight 90 is higher than the specific gravity of the motor cooling fan 40 .
  • the motor shaft 61 extends through the shaft through-hole 92 of the second weight 90 . Therefore, a reaction force works on the motor shaft 61 in reaction to the centrifugal force applied to the second weight 90 , and therefore the motor cooling fan 40 is prevented from being deformed due to the centrifugal force applied to the second weight 90 even when the motor cooling fan 40 is made from synthetic resin.
  • the dust collection fan 50 , the motor cooling fan 40 , the first weight 80 , and the second weight 90 are fixed to the motor shaft 61 by fastening them together. More specifically, as illustrated in FIG. 5 , a screw hole 66 is formed in the motor shaft 61 . The screw hole 66 extends from the lower end toward the upper side of the motor shaft 61 . The screw hole 66 is in communication with the hole 54 of the dust collection fan 50 . The inner diameter of the screw hole 66 is smaller than the inner diameter of the hole 54 . Further, a flange 67 is formed on the motor shaft 61 .
  • the flange 67 has an outer diameter larger than the inner diameter of the annular portion 91 of the second weight 90 , and the flange 67 and the annular portion 91 are axially in abutment with each other.
  • a plate 69 is placed in abutment with the lower edge of the bearing 64 below the motor shaft 61 .
  • a conical hole shaped so as to conform with the screw head of a flat-head machine screw 68 is formed at the center of the plate.
  • the dust collection fan 50 , the first weight 80 , the bearing 63 , the motor cooling fan 40 , and the second weight 90 are axially pressed tightly between the head portion of the bolt engaged with the lower end of the shaft portion 52 , and the flange 67 .
  • the dust collection fan 50 , the motor cooling fan 40 , the first weight 80 , and the second weight 90 are fixed to the motor shaft 61 . According to this configuration, the manufacturing process can be simplified.
  • the motor cooling fan 40 and the second weight 90 are individual separate members until they are fastened together in this manner, but they may be integrated during the manufacturing process.
  • the motor cooling fan 40 and the second weight 90 may be joined together by fixation using a bolt or may be manufactured integrally by insert-molding.
  • the first weight 80 and the second weight 90 are disposed at axially different positions, and therefore the centrifugal forces respectively applied to the first weight 80 and the second weight 90 can be prevented from being canceled out by each other.
  • the masses of the first weight 80 and the second weight 90 required to solve the couple unbalance can be reduced.
  • the first weight 80 and the second weight 90 are axially spaced apart from each other via the bearing 63 , a great axial distance can be secured between the first weight 80 and the second weight 90 .
  • the masses of the first weight 80 and the second weight 90 required to solve the couple unbalance can be further reduced.
  • the bearing 63 functions as a spacer for axially spacing the first weight 80 and the second weight 90 away from each other.
  • the bearing 63 originally required to rotatably support the motor shaft 61 can be utilized as the spacer, and therefore eliminates the necessity of disposing a spacer additionally. Therefore, the size of the sander 10 can be reduced and the manufacturing cost can be cut down.
  • a spacer may be additionally prepared and disposed between the first weight 80 and the second weight 90 .
  • the second embodiment is different from the first embodiment in terms of the fact that a balancer 180 is attached at the lower end of the motor shaft 61 instead of the first weight 80 attached to the dust collection fan 50 .
  • the balancer 180 has a center of gravity on the opposite side of the motor shaft 61 from the second weight 90 .
  • Such a configuration can also bring about advantageous effects equivalent to the first embodiment because the second weight 90 and the balancer 180 are axially spaced apart from each other.
  • the first weight 80 may be attached to the dust collection fan 50 instead of the second weight 90 attached to the motor cooling fan 40 , although this is not illustrated.
  • the third embodiment is different from the first embodiment in terms of the fact that the motor cooling fan 40 and the dust collection fan 50 are not axially spaced apart from each other.
  • the first weight 80 is attached to the lower side of the dust collection fan 50
  • the second weight 90 is attached to the upper side of the motor cooling fan 40 . Therefore, the first weight 80 and the second weight 90 are disposed at axially different positions.
  • Such a configuration can also contribute to reducing the masses of the first weight 80 and the second weight 90 required to solve the couple unbalance compared to the configuration in which the first weight 80 and the second weight 90 are disposed at the axially same position.
  • the fourth embodiment is different from the first embodiment in terms of the fact that a spindle 368 is disposed in parallel with the motor shaft 61 .
  • the motor shaft 61 and the spindle 368 are coupled via an endless belt 369 so as to be able to transmit power.
  • the tool accessory 30 is coupled at the distal end of the spindle 368 , although this is not illustrated.
  • the motor cooling fan 40 and the second weight 90 are attached at around the upper end of the spindle 368 , and a balancer 380 is attached at the lower end of the spindle 368 .
  • the balancer 380 has a center of gravity on the opposite side of the spindle 368 from the second weight 90 .
  • Such a configuration can also bring about advantageous effects equivalent to the first embodiment because the second weight 90 and the balancer 380 are axially spaced apart from each other.
  • the above-described embodiments can be applied to not only orbital sanders but also various portable electric tools accompanied by an eccentric circular motion.
  • the above-described embodiments can also be applied to random orbit sanders, polishers, and the like.
  • the sander 10 is one example of a “portable electric tool”.
  • the motor shaft 61 and the spindle 368 are one example of an “output shaft”.
  • the tool accessory 30 is one example of a “tool accessory”.
  • the dust collection fan 50 is one example of a “dust collection fan”.
  • the motor cooling fan 40 is one example of a “motor cooling fan”.
  • the electric motor 60 is one example of a “motor”.
  • the first weight 80 is one example of a “first weight”
  • the second weight 90 is one example of a “second weight”.
  • the second weight 90 and the first weight 80 can also be construed as one example of the “first weight”and one example of the “second weight”, respectively.
  • the balancers 180 and 380 are one example of the “first weight” or the “second weight”.
  • the bearing 63 is one example of a “spacer” and a “first bearing”.
  • the shaft portion 52 is one example of a “shaft portion”.
  • the bearing 64 is one example of a “second bearing”.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Grinding-Machine Dressing And Accessory Apparatuses (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Portable Power Tools In General (AREA)
US18/177,301 2022-03-22 2023-03-02 Portable electric tool Pending US20230302601A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022-045518 2022-03-22
JP2022045518A JP2023139802A (ja) 2022-03-22 2022-03-22 携帯用研磨機

Publications (1)

Publication Number Publication Date
US20230302601A1 true US20230302601A1 (en) 2023-09-28

Family

ID=87930953

Family Applications (1)

Application Number Title Priority Date Filing Date
US18/177,301 Pending US20230302601A1 (en) 2022-03-22 2023-03-02 Portable electric tool

Country Status (4)

Country Link
US (1) US20230302601A1 (de)
JP (1) JP2023139802A (de)
CN (1) CN116787283A (de)
DE (1) DE102023106563A1 (de)

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5854896B2 (ja) 2012-03-12 2016-02-09 株式会社マキタ サンダ

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CN116787283A (zh) 2023-09-22
JP2023139802A (ja) 2023-10-04
DE102023106563A1 (de) 2023-09-28

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