JP2017013166A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool which can suppress influence of brake dust.SOLUTION: In a grinder 1, a brake mechanism 50 applies brake force generated by friction to a motor 6 when an operation switch 5 selects OFF for the motor 6. The brake mechanism 50 is arranged on the windward side of cooling air generated by a fan 9 above the motor 6. A brake force generation part (mutual contact part between a brake pad 52 and a brake rotor 53) of the brake mechanism 50 is arranged in a brake housing space surrounded by an inner wall part 2d in a handle housing 2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power tool that applies a braking force to a motor when an operation switch is selected to turn off the motor.

  2. Description of the Related Art Conventionally, a power tool having a brake mechanism that applies a braking force to a motor when an operation switch is selected to turn off the motor, such as a grinder shown in Patent Document 1 below, is known. The brake mechanism that generates the braking force is desirably provided near the operation switch because it operates in conjunction with the operation switch. For this reason, when an operation switch exists behind the motor as in Patent Document 2 below, the brake mechanism is preferably arranged behind the motor.

JP 2004-249420 A JP 2012-61552 A

  As shown in Patent Documents 1 and 2, in the case of a configuration in which the cooling air generated by the fan flows from the rear of the motor to the front, if the brake mechanism is disposed behind the motor (upward of the cooling air), There was a problem that brake dust generated from the brake mechanism entered the motor by riding on cooling air.

  The present invention has been made in view of such a situation, and an object thereof is to provide a power tool capable of suppressing the influence of brake dust.

One embodiment of the present invention is a power tool. This power tool
A motor,
A housing for housing the motor;
An operation switch capable of switching on and off of the motor;
A brake mechanism that applies a braking force to the motor when the operation switch is selected to turn off the motor, and
The brake mechanism has a brake member movable so as to be close to and away from the motor, and exerts a braking force by bringing the brake member into contact with the motor.
The braking force generating portion of the brake mechanism is provided in a brake housing space whose periphery is covered with a partition wall in the housing.

The motor has a rotor;
The rotor is provided with a brake contact portion that can contact the brake member,
The brake contact portion is accommodated in the brake accommodating space so that the periphery is covered by the partition wall,
One of the rotor and the brake contact portion is provided with a projecting portion,
In the axial direction of the rotor, the partition wall and the projecting portion that overlap with the brake contact portion may form a communication path that communicates the brake housing space and the housing in a non-linear manner.

  A fan that generates cooling air in the housing may be provided, and the brake mechanism may be disposed above the cooling air from the motor.

  The housing may include a motor housing and a handle housing connected to one end of the motor housing, and the brake mechanism may be provided in the handle housing.

  The handle housing may be rotatable with respect to the motor housing.

  The handle housing may have a two-part structure and sandwich the brake mechanism.

  The handle housing may be coupled to the motor housing via vibration isolation means.

  An air inlet may be provided in the handle housing.

  It should be noted that any combination of the above-described constituent elements, and those obtained by converting the expression of the present invention between methods and systems are also effective as aspects of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the power tool which can suppress the influence of brake dust can be provided.

The top view which notched a part of motor housing 3 of the grinder 1 which concerns on embodiment of this invention. FIG. 3 is a side sectional view of the grinder 1 in a state where an operation switch 5 is turned off. The side sectional view in the state where operation switch 5 of grinder 1 is on. The principal part expanded plane sectional view in the state where the operation switch of the grinder 1 is OFF. FIG. 4 is an enlarged sectional view in the vicinity of a brake mechanism 50 in FIG. 3. AA sectional drawing of FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or equivalent component, member, etc. which are shown by each drawing, and the overlapping description is abbreviate | omitted suitably. In addition, the embodiments do not limit the invention but are exemplifications, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

  In the present embodiment, the configuration of the grinder 1 will be described as an example of a power tool with reference to FIGS. In addition, according to FIG. The grinder 1 includes a grindstone 10 as a tip tool (rotating tool), and is used for a grinding operation for flattening the surface of concrete, stone, or the like. The grindstone 10 has a disk shape and a diameter of, for example, 100 mm to 250 mm. In addition to the disc-shaped polishing grindstone or cutting grindstone, a disc-shaped brush or cutter can be attached as the tip tool. The grinder 1 includes a handle housing 2 (for example, made of resin), a motor housing 3 (for example, made of resin), and a gear case 4. The handle housing 2 and the motor housing 3 are examples of the housing of the present invention.

  The motor housing 3 has a substantially cylindrical shape as a whole, and a motor (electric motor) 6 is accommodated in the motor housing 3. Here, the motor 6 is a brush motor having a stator 6b and a rotor 6c. The motor 6 is connected to an external AC power source such as a commercial power source via the switch mechanism 8 and a power cord 7 drawn from the rear end of the handle housing 2. A fan 9 that rotates integrally with the output shaft 6 a of the motor 6 is provided in front of the motor 6 in the motor housing 3. The fan 9 generates cooling air that goes forward. The cooling air is taken into the handle housing 2 from a plurality of air inlets (wind windows) 2 c provided on both side surfaces of the handle housing 2, cools the motor 6 and the like, and has a plurality of exhaust ports (wind windows) provided in the gear case 4. ) Exhaust from 4a to the outside. A first bevel gear 21 is provided at the front end of the output shaft 6 a of the motor 6.

  The handle housing 2 is elastically attached (connected) to the rear end portion of the motor housing 3 via an elastic ring 31 as vibration isolating means. The handle housing 2 has a two-part structure, in which the left handle housing 2a and the right handle housing 2b are connected (coupled and integrated) with each other by a plurality of screws 101 (FIG. 1). The handle housing 2 can be rotated with respect to the motor housing 3 by releasing the handle lock by the handle lock operating portion 32. The handle housing 2 is provided with an operation switch (trigger switch) 5 for switching whether the motor 6 is energized (driving or stopping the motor 6). The operation switch 5 is rotatably supported on the handle housing 2 by a fulcrum 5a, and engages with a switch button 8a of a switch mechanism 8 that switches whether the motor 6 is energized. The switch button 8a is off when protruded as shown in FIG. 2, and is on when pressed as shown in FIG. The rotation of the operation switch 5 is transmitted to a later-described brake mechanism 50 through the link 5b. The link 5b is supported by the handle housing 2 so as to be rotatable by a fulcrum 5c (FIG. 5).

  The gear case 4 is made of a metal such as an aluminum alloy, and is attached to the front end portion of the motor housing 3. The opening at the lower end of the gear case 4 is closed by a packing land 11 as a lid member. The packing land 11 is fixed to the gear case 4 by screwing or the like. The packing land 11 serves as a holding member that holds a foil guard 30 described later. A spindle 20 is rotatably held inside the gear case 4. The spindle 20 is substantially orthogonal to the output shaft 6a (rotor rotation shaft) of the motor 6, and one end thereof penetrates the packing land 11 and protrudes to the outside. On the other hand, a second bevel gear 22 that meshes with a first bevel gear 21 attached to the output shaft 6 a of the motor 6 is provided (attached) on the other end side of the spindle 20 located in the gear case 4. The rotation of the motor 6 is converted by the first bevel gear 21 and the second bevel gear 22 serving as a rotation transmission mechanism (deceleration unit) by 90 degrees, and the rotation speed is reduced and transmitted to the spindle 20. That is, the spindle 20 is rotationally driven by the motor 6.

  The grindstone 10 is fixed to the spindle 20 by a wheel washer and a lock nut, and rotates integrally with the spindle 20. When the operation switch 5 provided in the handle housing 2 is operated, electric power is supplied to the motor 6 and the output shaft 6a of the motor 6 rotates. Then, the spindle 20 connected to the output shaft 6a via the first bevel gear 21 and the second bevel gear 22 rotates, and the grindstone 10 fixed to the spindle 20 rotates. A foil guard 30 that covers at least half or more of the outer periphery of the grindstone 10 is attached to the packing land 11. The wheel guard 30 is prevented from rotating during the operation so that its rotation position does not change, and if the rotation prevention is released, the rotation position can be changed according to the work contents.

  Hereinafter, the brake mechanism 50 of the grinder 1 will be described. The brake mechanism 50 applies a braking force by friction to the motor 6 when the operation switch 5 selects that the motor 6 is off. The brake mechanism 50 is disposed above the cooling air generated by the fan 9 rather than the motor 6. As shown in FIGS. 4 to 6, the braking force generating portion (the mutual contact portion between the brake pad 52 and the brake rotor 53) of the brake mechanism 50 is an inner wall portion (inner wall rib) whose periphery is a partition wall in the handle housing 2. It is provided in the brake accommodating space covered with 2d. The inner wall 2d protrudes from the inner surfaces of the left handle housing 2a and the right handle housing 2b and is abutted against each other (FIG. 6).

  The brake mechanism 50 includes a brake holder 51 as a holding member, a brake pad 52 as a brake member, a brake rotor 53 as a brake contact portion, and a pair of springs 54 (FIG. 5). The brake holder 51 includes a main body portion 51a that holds the brake pad 52, a shaft portion 51b, and a flange portion 51c as an engaging portion. The main body 51a is located in the brake accommodating space. As shown in FIG. 4, the main body 51a has a pair of notches 51e, and support walls (support ribs) 2e rising from the inner surfaces of the left handle housing 2a and the right handle housing 2b enter the notches 51e and brake. The holder 51 is supported (clamped). The shaft portion 51b rises from the rear end surface of the main body portion 51a and extends rearward from the inside to the outside of the brake accommodating space. The shaft portion 51b has a small diameter portion 51d outside the brake accommodating space, and the flange portion 51c is provided at the rear end portion of the small diameter portion 51d. The flange portion 51 c engages with the tip of a U-shaped or U-shaped link 5 b that rotates in conjunction with the operation switch 5. The shaft portion 51b approaches or contacts the inner wall portion 2d of the handle housing 2 over the entire circumference.

  The brake pad 52 is provided on the front end surface of the main body 51 a of the brake holder 51 and is located in the brake accommodating space. The brake rotor 53 is located in the brake accommodating space, is provided so as to be able to rotate integrally with the output shaft 6a of the motor 6 (for example, attached by a bolt 57 as shown in FIG. It faces the front end face of the main body 51a. As shown in FIG. 5, the pair of springs 54 is provided between the main body 51 a of the brake holder 51 and the inner wall 2 d of the handle housing 2 at the top and bottom of the shaft 51 b of the brake holder 51. Energize forward.

  In front of the brake rotor 53, a collar (tubular body) 55 is provided around the rotation shaft (output shaft 6a) of the rotor 6c (press-fitted into the rotor rotation shaft). The collar 55 has a role of determining an axial position of the brake rotor 53. The collar 55 has flange portions 55b and 55c as projecting portions having different axial positions on the outer peripheral surface. The inner wall portion 2d of the handle housing 2 enters the concave groove 55a between the flange portions 55b and 55c with a slight gap over the entire circumference (having a labyrinth structure). The inner wall portion 2d and the flange portions 55b and 55c of the handle housing 2 whose radial position overlaps with the brake rotor 53 form a communication path that communicates in and out of the brake accommodating space in a non-linear manner.

  As shown in FIG. 2, when the operation switch 5 is in the OFF state, the brake holder 51 is urged forward (brake rotor 53 side) by the spring 54, the brake pad 52 is pressed against the brake rotor 53, and the brake mechanism 50 The braking force works. On the other hand, as shown in FIGS. 3 and 5, when the operation switch 5 is on, the link 5 b that rotates in conjunction with the operation of turning on the operation switch 5 is caught by the flange portion 51 c of the brake holder 51. The brake holder 51 is retracted (engaged) against the bias of the spring 54, the brake pad 52 is separated from the brake rotor 53, and the braking force by the brake mechanism 50 is lost (the brake mechanism 50 is released). .

  According to the present embodiment, the following effects can be achieved.

(1) Since the braking force generating portion of the brake mechanism 50 is provided in the brake housing space whose periphery is covered with the inner wall portion 2d in the handle housing 2, most of the brake dust generated from the brake mechanism 50 is the brake housing space. The brake dust is prevented from entering the motor 6. In particular, when the motor 6 is a motor with a brush, when brake dust enters the contact area of the brush, the energization efficiency to the motor 6 is reduced, but this can be effectively suppressed. .

(2) Since the inner wall portion 2d of the handle housing 2 enters between the flange portions 55b and 55c of the collar 55 and forms a labyrinth structure over the entire circumference in front of the braking force generating portion, the inner wall portion that rotates relatively Brake dust can be prevented from going out of the brake accommodating space from between 2d and the collar 55.

(3) Since the operation switch 5 and the brake mechanism 50 are both located behind the motor 6, the mechanism (link 5b) for operating the brake mechanism 50 in conjunction with the operation switch 5 can be configured in a small and simple configuration.

  The present invention has been described above by taking the embodiment as an example. However, it is understood by those skilled in the art that various modifications can be made to each component and each processing process of the embodiment within the scope of the claims. By the way. Hereinafter, modifications will be described.

  Either of the flange portions 55b and 55c of the collar 55 may be omitted. The brake rotor 53 may be provided with projecting portions corresponding to the flange portions 55b and 55c of the collar 55 to form a labyrinth structure with the inner wall portion 2d of the handle housing 2. In this case, a part of the brake rotor 53 may be outside the brake accommodating space. The power tool may be of a type other than the grinder. For example, the present invention is suitable for a power tool to which a rotating tool having a relatively large moment of inertia such as a circular saw, a concrete cutter, a brush cutter, and a lawn mower can be attached. The motor 6 may be a brushless motor.

1 grinder, 2 handle housing, 2a left handle housing, 2b right handle housing, 2c air inlet (wind window), 2d inner wall (inner wall rib), 2e support wall (support rib), 3 motor housing, 4 gear case, 4a exhaust Mouth (wind window), 5 operation switch (trigger switch), 5a fulcrum, 5b link, 5c fulcrum, 6 motor (electric motor), 6a output shaft (rotor rotation shaft), 6b stator, 6c rotor, 7 power cord, 8 switch Mechanism, 8a switch button, 9 fan, 10 grindstone, 11 packing land (holding member), 20 spindle, 21 first bevel gear, 22 second bevel gear, 30 wheel guard, 31 elastic ring, 32 handle lock operation part, 50 Brake mechanism, 51 Brake holder, 51a Body part, 51b Shaft part, 51c Flange part, 51d Small diameter part, 51e Notch part, 52 Brake pad, 53 Brake rotor, 54 Spring, 55 Collar (cylindrical body), 55a Concave groove, 55b, 55c Flange part (projecting) Part), 57 bolt, 101 screw

Claims (8)

A motor,
A housing for housing the motor;
An operation switch capable of switching on and off of the motor;
A brake mechanism that applies a braking force to the motor when the operation switch is selected to turn off the motor, and
The brake mechanism has a brake member movable so as to be close to and away from the motor, and exerts a braking force by bringing the brake member into contact with the motor.
The braking force generating portion of the brake mechanism is a power tool provided in a brake accommodating space whose periphery is covered with a partition wall in the housing. The motor has a rotor;
The rotor is provided with a brake contact portion that can contact the brake member,
The brake contact portion is accommodated in the brake accommodating space so that the periphery is covered by the partition wall,
One of the rotor and the brake contact portion is provided with a projecting portion,
The axial direction of the rotor WHEREIN: The said partition and the said protrusion part which overlap with the said brake contact part form the communicating path which connects the said brake accommodating space and the inside of the said housing non-linearly. The described power tool.   The power tool according to claim 1, further comprising a fan that generates cooling air in the housing, wherein the brake mechanism is disposed on the cooling air from the motor.   The said housing has a motor housing and the handle housing connected with the end of the said motor housing, The said brake mechanism is provided in the said handle housing, The any one of Claim 1 to 3 The described power tool.   The power tool according to claim 4, wherein the handle housing is rotatable relative to the motor housing.   The power tool according to claim 4 or 5, wherein the handle housing has a two-part structure and sandwiches the brake mechanism.   The power tool according to any one of claims 4 to 6, wherein the handle housing is connected to the motor housing via vibration isolation means.   The power tool according to claim 4, wherein an air inlet is provided in the handle housing.

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