JP2017013164A - Power tool - Google Patents

Abstract

Provided is a power tool that has better workability when the rotation of a spindle is restricted by a rotation restriction mechanism as compared with the prior art. A grinder including a rotation restricting mechanism for restricting rotation of a spindle, and in a state in which a lock pin for spindle lock is half-pressed, a brake holder is connected to a spring by interlocking with the descent of the lock pin. The brake pad 52 is moved away from the brake rotor 53 and the braking force by the brake mechanism is reduced. [Selection] Figure 10

Description

  The present invention relates to a power tool that applies a braking force to a prime mover when an operation switch selects the prime mover off.

  2. Description of the Related Art Conventionally, a power tool having a brake mechanism that applies a braking force to a prime mover when an operation switch selects the prime mover off, such as a grinder shown in Patent Document 1 below, is known. When the grindstone is exchanged in the grinder, for example, a fixing pin provided in the gear case is engaged with the engaging portion on the spindle side in order to restrict the rotation of the spindle.

JP 2004-249420 A

  Since the fixing pin provided in the gear case and the engaging portion on the spindle side can be engaged at a predetermined rotational position, the user rotates the spindle while pressing the pin to engage the pin with the engaging portion. I will let you. In the conventional power tool, when the operation switch is selected to turn off the prime mover, a braking force is applied to the prime mover. Therefore, the torque required to rotate the spindle to align the rotational position of the pin and the engaging portion is increased. It was big and the workability was bad.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a power tool having better workability when the rotation of the spindle is regulated by a rotation regulating mechanism as compared with the conventional one.

One embodiment of the present invention is a power tool. This power tool
Prime mover,
A housing that houses the prime mover;
An operation switch capable of switching the prime mover on and off;
A brake mechanism that applies a braking force to the prime mover when the operation switch selects the prime mover off;
A spindle driven to rotate by the prime mover;
A rotation transmission mechanism for transmitting rotation of the prime mover to the spindle;
A rotation regulating mechanism capable of regulating the rotation of the spindle;
An operator for enabling the restriction by the rotation restricting mechanism,
When the operation unit is operated, the braking force by the brake mechanism is reduced compared to the case where the operation unit is not operated.

  When the operation unit is operated, the braking force by the brake mechanism may be eliminated.

  A transmission member that transmits the operation of the operation unit to the brake mechanism may be provided, and the braking force by the brake mechanism may be reduced by the operation of the transmission member by the operation of the operation unit.

  A detection switch that detects an operation of the operation unit, and an actuator that is activated when the operation of the operation unit is detected by the detection switch. Even if the braking force by the brake mechanism is reduced by the operation of the actuator Good.

  A control unit that controls driving of the prime mover is provided, and the control unit may not operate the prime mover when an operation of the operation unit is detected by the detection switch.

  A fan that generates cooling air directed forward in the housing may be provided, and the brake mechanism may be disposed in front of the prime mover in the 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.

  According to the present invention, it is possible to provide a power tool having better workability when the rotation of the spindle is regulated by the rotation regulating mechanism as compared with the conventional art.

FIG. 3 is a plan view of the grinder 1 according to the first embodiment of the present invention in which a part of the housing 3 is cut out in a state where the operation switch 5 is off and the lock pin 40 is not pressed. The principal part enlarged view of FIG. The side sectional view of the grinder 1 in the same state as FIG. The principal part enlarged view of FIG. The front view which notched a part of gear case 4 of the grinder 1 of the same state as FIG. The principal part enlarged view of FIG. FIG. 3 is a plan view of the grinder 1 with a part of the housing 3 cut away in a state where the operation switch 5 is turned off and the lock pin 40 is half-pressed. The principal part enlarged view of FIG. FIG. 8 is a side sectional view of the grinder 1 in the same state as in FIG. 7. The principal part enlarged view of FIG. The front view which notched a part of gear case 4 of the grinder 1 of the same state as FIG. The principal part enlarged view of FIG. FIG. 3 is a side sectional view of the grinder 1 in a state where the operation switch 5 is on and the lock pin 40 is not pressed. The sectional side view in the state where the operation switch 5 is OFF and the lock pin 40 is not pushed, of the grinder 2 according to Embodiment 2 of the present invention. FIG. 3 is a side sectional view of the grinder 2 in a state where the operation switch 5 is turned off and the lock pin 40 is half-pressed. The control block diagram of the grinder 2. 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, process, 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.

Embodiment 1
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. As shown in FIG. 3, 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 housing 3 (for example, made of resin) and a gear case 4.

  The housing 3 has a substantially cylindrical shape as a whole, and a motor (electric motor) 6 as a prime mover is accommodated in the housing 3. The housing 3 holding the motor 6 is used as a handle of the grinder 1. The motor 6 is a motor with a brush here. The motor 6 is connected to an external AC power source such as a commercial power source via a power cord 7 drawn from the rear end of the housing 3. 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 housing 3. The fan 9 generates cooling air that goes forward. The cooling air is taken into the housing 3 from a plurality of air inlets (wind windows) 3b provided at the rear portion of the housing 3 to cool the motor 6 and the like, and from a plurality of air outlets (wind windows) 4a provided in the gear case 4. Exhausted outside. A first bevel gear 21 is provided at the front end of the output shaft 6 a of the motor 6. The housing 3 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 includes an operation portion 5 a exposed on the surface of the housing 3, and a slide bar 5 b that engages with the operation portion 5 a and extends forward and backward in the housing 3. The rear end portion of the slide bar 5b is engaged with a switch lever 8 that switches whether the motor 6 is energized. The switch lever 8 is off when tilted backward as shown in FIG. 3, and is on when tilted forward as shown in FIG. The operation switch 5 is urged rearward (in the direction in which it is turned off) by a spring 5c as urging means, but the operation portion 5a is slid forward to the locking projection 3a shown in FIG. By hooking, the operation switch 5 can be locked in the ON state (the switch lever 8 is tilted forward). The operation switch 5 in the on state is shown in FIG.

  The gear case 4 is made of a metal such as an aluminum alloy, and is attached to the front end portion of the 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 housing 3 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.

  The gear case 4 is provided with a lock pin (lock member) 40 for locking the spindle for restricting (fixing) the rotation of the spindle 20 when the grindstone 10 is replaced. As shown in FIGS. 4 and 6, the lock pin 40 includes a flange portion 40 a exposed above the gear case 4 and a pin portion 40 b extending from the flange portion 40 a into the gear case 4. The second bevel gear 22 is provided with a hole (engagement portion) 22a into which the tip of the pin portion 40b of the lock pin 40 can be fitted (engaged). The pin portion 40b of the lock pin 40 and the hole portion 22a of the second bevel gear 22 are examples of the rotation restricting mechanism of the present invention. Moreover, the flange part 40a of the lock pin 40 is an illustration of the operation part of the present invention for enabling the restriction by the rotation restriction mechanism.

  In order to validate the restriction (spindle lock) by the rotation restricting mechanism, the lock pin 40 is pushed down (half-pressed) until it approaches the upper surface of the second bevel gear 22, the grindstone 10 is rotated, and the pin of the lock pin 40 is rotated. The pin portion 40b may be pushed into the hole portion 22a when the position of the hole portion 22a of the second bevel gear 22 is aligned with the portion 40b. The lock pin 40 is urged upward by a spring 41 as an urging means. When the hand is released from the lock pin 40, the lock pin 40 comes out of the hole 22a of the second bevel gear 22, and the spindle lock Is released.

  A brake mechanism is provided in front of the motor 6 and the fan 9 in the housing 3. The brake mechanism applies a braking force to the motor 6 when the operation switch 5 selects that the motor 6 is off. The brake mechanism includes a brake holder 50, a spring 51 as an urging means, a brake pad 52, and a brake rotor 53. The lower part of the brake holder 50 is rotatably supported by the housing 3. The brake holder 50 is urged rearward by the spring 51. The brake pad 52 is provided on the rear surface of the brake holder 50. The brake rotor 53 is provided (attached) so as to be integrally rotatable with the output shaft 6 a of the motor 6, and faces the rear surface of the brake holder 50 with the brake pad 52 interposed therebetween.

  1 to 6, that is, in a state where the operation switch 5 is OFF and the lock pin 40 is not pressed, the brake holder 50 is biased toward the brake rotor 53 by the spring 51, and the brake pad 52 is moved to the brake rotor 53. The braking force is applied by the brake mechanism. On the other hand, although details will be described later, in the state shown in FIGS. 7 to 12, that is, in the state where the operation switch 5 is turned off and the lock pin 40 is half-pressed, the brake holder 50 is moved in accordance with the lowering of the lock pin 40. The brake pad 52 is separated from the brake rotor 53 and the braking force by the brake mechanism is reduced (preferably the braking force is lost). In the state shown in FIG. 13, that is, in the state where the operation switch 5 is on and the lock pin 40 is not pressed, the brake holder 50 is rotated forward against the bias of the spring 51 by the slide bar 5 b of the operation switch 5. The brake pad 52 is moved away from the brake rotor 53, and the braking force by the brake mechanism is lost (the brake is released).

  Hereinafter, a configuration for reducing the braking force by the brake mechanism when the lock pin 40 is in the half-pressed state will be described. As shown in FIGS. 2 and 4, the brake holder 50 is provided with a tongue piece (engaging portion) 50 a that extends obliquely forward (rises). On the other hand, as shown in FIGS. 2, 4, and 6, the transmission member 42 that transmits the operation (vertical movement) of the lock pin 40 to the tongue piece 50 a is rotatably supported by the gear case 4. The transmission member 42 includes a shaft portion 42a and arm portions 42b and 42c. The shaft portion 42 a is rotatably supported by the gear case 4. The arm portion 42 b extends from the front end portion of the shaft portion 42 a and engages with the lock pin 40. The arm portion 42 c extends from the rear end portion of the shaft portion 42 a and engages with the tongue piece portion 50 a of the brake holder 50. The three parts of the shaft part 42a and the arm parts 42b and 42c are orthogonal to each other.

  6 and 12, when the lock pin 40 is half-pressed, the transmission member 42 has the arm portion 42b pushed downward by the flange portion 40a of the lock pin 40, and counterclockwise when viewed from the front. Rotate to. Then, the engagement state of the arm portion 42c and the tongue piece portion 50a changes from the state of FIG. 2 to the state of FIG. 8 (the arm portion 42c slides along the slope of the tongue piece portion 50a), and the brake holder 50 As shown in FIG. 10, it is pulled by the piece 50a and rotates forward as shown in FIG. 10, the brake pad 52 is separated from the brake rotor 53, and the braking force by the brake mechanism is reduced (preferably Will be zero). When the hand is released from the lock pin 40, the lock pin 40 returns upward due to the urging of the spring 41, the transmission member 42 also returns to the original rotational position shown in FIG. 6, and the braking force by the brake mechanism is restored.

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

(1) Since the braking force by the brake mechanism is reduced when the lock pin 40 is half-pressed, the operator can rotate the grindstone 10 with a light force (torque) after half-pressing the lock pin 40. The relative position between the pin portion 40b of the pin 40 and the hole portion 22a of the second bevel gear 22 can be easily aligned, and the workability of the spindle lock is improved.

(2) Since the brake mechanism is provided in front of the motor 6 (downward of the cooling air from the motor 6), the brake dust can be prevented from entering the motor 6.

Embodiment 2
In the present embodiment, the configuration of the grinder 2 will be described as an example of a power tool with reference to FIGS. The grinder 2 is different from the grinder 1 shown in the first embodiment in the configuration for reducing the braking force by the brake mechanism when the lock pin 40 is half-pressed. As shown in FIG. 14, the gear case 4 holds a micro switch 61 that engages with the flange portion 40 a of the lock pin 40. The micro switch 61 is a detection switch that detects a half-press of the lock pin 40. The micro switch 61 is turned off when the lock pin 40 is not pushed, and turned on when the lock pin 40 is pushed more than half-pressed.

  An actuator 62 is held in the housing 3 and the gear case 4. The actuator 62 linearly moves the movable member 63 (see the enlarged portion in FIGS. 14 and 15) with an electromagnet, and is, for example, a solenoid actuator having a solenoid and a spring therein. When the actuator 62 is activated, the movable member 63 is pulled in by electromagnetic force (FIG. 15), and when the actuator 62 is stopped, the movable member 63 is pushed out by a spring (FIG. 14). The spring in the actuator 62 may be omitted. The actuator 62 starts when one of the micro switch 61 and the operation switch 5 is turned on, and stops when both the micro switch 61 and the operation switch 5 are turned off.

  14 and 15, the movable member 63 of the actuator 62 includes a pin portion 63a and a flange portion 63b. A flange portion 63b is provided at the tip of the pin portion 63a. The flange portion 63 b engages with the tongue piece portion 50 a of the brake holder 50. The tongue piece portion 50 a is an engaging portion that extends in a hook shape from the brake holder 50 and is hooked (engaged) with the flange portion 63 b of the movable member 63.

  As shown in FIG. 14, when the operation switch 5 is off and the lock pin 40 is not pressed, the actuator 62 is stopped and no pulling force is applied to the movable member 63, and the brake holder 50 is moved to the brake rotor 53 by the spring 51. The brake pad 52 is pressed against the brake rotor 53, and the braking force by the brake mechanism works. On the other hand, as shown in FIG. 15, when the operation switch 5 is turned off and the lock pin 40 is half-pressed, the micro switch 61 is turned on by the flange portion 40 a of the lock pin 40 and the actuator 62 is activated to move the movable member 63. Is pulled in and the brake holder 50 pulls the tongue 50a forward, the brake holder 50 rotates forward against the bias of the spring 51, the brake pad 52 is separated from the brake rotor 53, and the brake mechanism The braking force becomes small (preferably zero). Similarly, when the operation switch 5 is turned on, the braking force by the brake mechanism is lost by the operation of the actuator 62. In this embodiment, even when the operation switch 5 is turned on, the brake holder 50 is rotated forward by the actuator 62 to eliminate the braking force. Therefore, the slide bar 5b of the operation switch 5 is compared with the first embodiment. It is shorter forward.

  A controller 60 as a control unit is provided at the rear part in the housing 3. The controller 60 controls each block constituting the motor driving circuit 70 shown in FIG. 16 and controls the driving of the motor 6. In the motor drive circuit 70, a power supply circuit 71 is a circuit for supplying a current to a controller 60 and an actuator 62 made of, for example, a microcomputer. The controller 60 monitors on / off of the microswitch 61. When the microswitch 61 is turned on, the switching element 72 such as an FET is turned on, and the output current of the power supply circuit 71 is supplied to the actuator 62 to start the actuator 62 ( Release the braking force by the brake mechanism). When the micro switch 61 is on, the controller 60 does not operate the motor 6 even if the operation switch 5 is turned on. The resistor 73 is a detection resistor that detects a current flowing through the motor 6. When the controller 60 detects the terminal voltage of the resistor 73 and detects that the current flowing through the motor 6 exceeds a predetermined value, the controller 60 turns off the switching element 74 such as a triac and stops the energization of the motor 6 (overcurrent). Prevention function).

  Other points of the present embodiment are the same as those of the first embodiment. The present embodiment can achieve the same effects as those of the first embodiment. In the present embodiment, if the power cord 7 is disconnected when the operation switch 5 is turned on, the actuator 62 stops and the braking force by the brake mechanism is restored. Therefore, when the power cord 7 is disconnected during work, the grindstone 10 Can be stopped quickly. Further, since the controller 60 does not operate the motor 6 even when the operation switch 5 is turned on when the micro switch 61 is turned on, the grindstone 10 rotates even if the operation switch 5 is turned on unexpectedly when the grindstone 10 is replaced. Can reduce the risk.

  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.

  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. The prime mover may be other than an electric motor (such as an engine).

1, 2 grinder, 3 housing, 3a locking projection, 3b air inlet (wind window), 4 gear case, 4a exhaust port (wind window), 5 operation switch (trigger switch), 5a operation section, 5b slide bar, 5c spring, 6 motor (electric motor), 6a output shaft, 7 power cord, 8 switch lever, 9 fan, 10 grinding wheel, 11 packing land (holding member), 20 spindle, 21 first bevel gear, 22 second bevel gear, 22a hole Part (engagement part), 30 wheel guard, 40 lock pin (lock member), 40a flange part (operation part), 40b pin part, 41 spring, 42 transmission member, 50 brake holder, 50a tongue piece part (engagement part) ), 51 Spring, 52 Brake pad, 53 Brake rotor, 60 Controller (Control) Control part), 61 micro switch (detection switch), 62 actuator, 63 movable member, 63a pin part, 63b flange part, 70 motor drive circuit, 71 power supply circuit, 72 switching element, 73 resistance, 74 switching element

Claims (6)

Prime mover,
A housing that houses the prime mover;
An operation switch capable of switching the prime mover on and off;
A brake mechanism that applies a braking force to the prime mover when the operation switch selects the prime mover off;
A spindle driven to rotate by the prime mover;
A rotation transmission mechanism for transmitting rotation of the prime mover to the spindle;
A rotation regulating mechanism capable of regulating the rotation of the spindle;
An operator for enabling the restriction by the rotation restricting mechanism,
A power tool characterized by reducing a braking force by the brake mechanism when the operation unit is operated as compared to a case where the operation unit is not operated.   The power tool according to claim 1, wherein when the operation unit is operated, a braking force by the brake mechanism is eliminated.   The power tool according to claim 1, further comprising: a transmission member that transmits an operation of the operation unit to the brake mechanism, wherein a braking force by the brake mechanism is reduced by an operation of the transmission member by an operation of the operation unit.   A detection switch that detects an operation of the operation unit, and an actuator that is activated when an operation of the operation unit is detected by the detection switch, and the braking force by the brake mechanism is reduced by the operation of the actuator. Item 3. The power tool according to Item 1 or 2.   The power tool according to claim 3, further comprising a control unit that controls driving of the prime mover, wherein the control unit does not operate the prime mover when an operation of the operation unit is detected by the detection switch.   6. The power tool according to claim 1, further comprising a fan that generates cooling air directed forward in the housing, wherein the brake mechanism is disposed in front of the prime mover in the housing.

Images