Patent Application
20210094147
This application claims the benefit of priority to Japanese Patent Application No. 2019-175940, filed on Sep. 26, 2019, the entire contents of which are hereby incorporated by reference.
The present invention relates to a grinder including a brake assembly that applies a brake to a rotating output shaft of a motor and an interlocking assembly that turns on or off the brake assembly in cooperation with a switch lever.
A known grinder described in, for example, Japanese Unexamined Patent Application Publication No. 2018-111185 includes a brake assembly including a brake plate, a brake member, and a coil spring. The brake plate is fixed to an output shaft of a motor. The brake member faces the brake plate in front and includes a brake shoe. The coil spring presses the brake member toward the brake plate.
The known grinder includes an interlocking assembly including a slide bar. A switch lever turns on or off a switch for driving the motor. When the switch lever is depressed, the slide bar advances toward the brake member to move the brake shoe away from the brake plate. The interlocking assembly is a link member that advances the slide bar when the switch lever is depressed and retracts the slide bar when the switch lever is returned to an initial position. A lever member is located behind the switch lever. The lever member is in contact with a plunger included in the switch and swings vertically in cooperation with the switch lever.
When the switch lever is depressed, the slide bar advances via the link member to cause the brake assembly to release the brake. At the same time, the lever member is depressed and the switch is then turned on to rotate the output shaft. When the switch lever is released from being depressed, the lever member is released from being depressed and the switch is then turned off. At the same time, the slide bar retracts and the brake assembly then operates to apply a brake on the output shaft.
In the known interlocking assembly, the link member releases and operates the brake assembly, and the lever member turns on and off the switch. This structure increases the number of components and can cause a cumulative tolerance lowering the operability or causing the brake assembly and the switch to operate at different times.
One or more aspects of the present invention are directed to a grinder that has a simple structure with fewer components to allow a brake assembly and a switch to operate easily and reliably.
A first aspect of the present invention provides a grinder, including:
A second aspect of the present invention provides a grinder, including:
The structure according to the above aspects of the present invention causes the slide bar for turning on and off the brake assembly to turn on and off the switch directly or indirectly via the link member. This structure reduces the number of components and eliminates the likelihood of a cumulative tolerance lowering the operability or causing the brake assembly and the switch to operate at different times. In other words, both the brake assembly and the switch may be operated easily and reliably with a simple structure including fewer components.
Embodiments of the present invention will now be described with reference to the drawings.
The motor housing 3 is cylindrical and holds the motor 4 facing frontward. The brake holder 5 is cylindrical. A bearing plate 13 holding a bearing 14 is located between the brake holder 5 and the gear housing 6. The motor 4 includes its output shaft 15 extending through the brake holder 5 and held on the bearing plate 13 via the bearing 14. The output shaft 15 has its distal end protruding into the gear housing 6. The output shaft 15 receives a first bevel gear 16 fastened to the distal end.
The motor 4 is a commutator motor. The motor 4 includes a stator 17 and a rotor 18. The stator 17 is held on the motor housing 3. The rotor 18 extends through the stator 17 and includes the output shaft 15 along its axis. The rotor 18 includes a commutator 19 in its rear portion. The output shaft 15 receives a fan 20 for cooling the motor located in front of the stator 17. The motor housing 3 includes a baffle plate 21 in its front portion. The baffle plate 21 covers the outer periphery of the fan 20 from the rear. The output shaft 15 has its rear end held, via a bearing 23, by a holder 22 in the rear portion of the motor housing 3.
The spindle 8 is held, via upper and lower bearings 24, orthogonal to the output shaft 15 inside the gear housing 6 and a bearing box 6a, which is located in the lower portion of the gear housing 6. The spindle 8 receives, on its upper portion, a second bevel gear 25 meshing with the first bevel gear 16. The spindle 8 has its lower end protruding from the bearing box 6a. The lower end of the spindle 8 may receive a tip tool 28, such as a grinding disc, in a detachable manner with an inner flange 26 and an outer flange 27. The bearing box 6a includes a tool cover 29 on its lower portion. The tool cover 29 covers the rear half of the tip tool 28 from above. The gear housing 6 has multiple outlets 30 in its upper front surface.
The brake assembly 7 includes a brake plate 31, a brake member 32, and a coil spring 33. The brake plate 31 is integrally fixed to the output shaft 15. The brake member 32 receives the output shaft 15 extending through it, and is located in front of the brake plate 31 in a manner movable back and forth. The brake member 32 includes a brake shoe 34 on its rear surface. The coil spring 33 receives the output shaft 15 extending through it, and is located in front of the brake member 32. The coil spring 33 urges the brake member 32 rearward.
In a normal state, the brake member 32 is urged by the coil spring 33 to a braking position (on position), at which the brake shoe 34 is pressed against the brake plate 31. When pressed frontward against the urging force from the coil spring 33, the brake member 32 is at a brake release position (off position), at which the brake shoe 34 is away from the brake plate 31.
The rear cover 9 is shaped in a cup that opens frontward. The rear cover 9 accommodates the holder 22 of the motor housing 3 and a switch receiver 35. The switch receiver 35 is integral with the rear of the holder 22. The switch receiver 35 holds the switch 11 to have a plunger 36 protruding rearward. The switch 11 is a push switch. The switch 11 is turned on when the plunger 36 is depressed. The controller 10 is laterally accommodated to extend in the front-rear direction above the switch 11. The rear cover 9 has multiple inlets 37 (
A lever holder 40 is located on the lower surfaces of the motor housing 3 and the rear cover 9. The lever holder 40 has an opening extending in the front-rear direction. The lever holder 40 includes a switch lever 41. The switch lever 41 is used to turn on or off the switch 11. The switch lever 41 is a strip plate in a plan view and extends in the front-rear direction along the opening of the lever holder 40. The switch lever 41 has its front end engaged with the front edge of the lever holder 40 from inside the rear cover 9. The switch lever 41 includes right and left side plates 42 and a rear plate 43 that each stand upward. The right and left side plates 42 have a pair of engagement tabs 44 protruding into the rear cover 9 with the lever holder 40 in between as shown in
In other words, the switch lever 41 is held in a manner swingable about its front end in the vertical direction. When swung downward, the switch lever 41 is stopped where the engagement tabs 44 are engaged with the inner surface of the rear cover 9. This stop position is the initial position of the switch lever 41, at which the switch lever 41 protrudes downward through the opening of the lever holder 40.
An interlocking assembly 50 is located above the switch lever 41. The interlocking assembly 50 turns on or off the brake assembly 7 in cooperation with the operation of the switch lever 41. The interlocking assembly 50 includes a slide bar 51 and a link member 52.
The slide bar 51 is a plate narrower than the interval between the engagement tabs 44. The slide bar 51 extends in the front-rear direction. The slide bar 51 has its front end protruding frontward from the motor housing 3 to be in contact with the rear surface of the brake member 32 at the braking position. The slide bar 51 includes a standing portion 53 in its rear end. The rear end of the slide bar 51 is located rearward from the switch 11. The standing portion 53 stands upward behind the plunger 36.
The link member 52 is held by a pin 54, which extends in the lateral direction, in a rotatable manner below the holder 22. The link member 52 includes a front arm 55 and a rear arm 56. The front arm 55 and the rear arm 56 radially protrude with a predetermined angle between them in the rotation direction. The front arm 55 has its distal end located above the slide bar 51 and in contact with the upper ends of the engagement tabs 44. The rear arm 56 has its lower end engaged with the switch lever 41 through a through-hole 45 below the link member 52 in the switch lever 41.
When the brake member 32 is at the braking position, the slide bar 51 is at a retracted position to have the standing portion 53 located behind the plunger 36 without depressing the plunger 36 as shown in
In this state, when the switch lever 41 is depressed toward the rear cover 9, the right and left engagement tabs 44 are raised to press the front arm 55 upward. This causes the link member 52 to rotate clockwise in
As the slide bar 51 slides frontward, the advanced standing portion 53 depresses the plunger 36 to turn on the switch 11. In this manner, when the switch lever 41 is depressed, the slide bar 51 is at the advanced position and the link member 52 is at the right rotational position.
To operate the grinder 1 according to the present embodiment, the switch lever 41 is depressed with fingers holding the motor housing 3 and the rear cover 9 forming a grip. The engagement tabs 44 then raise the front arm 55 to rotate the link member 52 to the right rotational position as shown in
When the fan 20 rotates as the output shaft 15 rotates, outside air is drawn through the inlets 37 in the rear end of the rear cover 9. The drawn air flows through the rear cover 9 and the motor housing 3 to cool the motor 4, then through the brake holder 5, and exits through the outlets 30 in the gear housing 6.
When the switch lever 41 is released from being depressed, the coil spring 33 urges the brake member 32 back to the braking position. In other words, the brake shoe 34 is pressed against the brake plate 31 to apply a brake on the rotating output shaft 15. At the same time, the brake member 32 slides the slide bar 51 to the retracted position. The slide bar 51 then pulls the rear arm 56 rearward to return the link member 52 to the left rotational position, and at the same time, moves the standing portion 53 rearward away from the plunger 36 to turn off the switch 11. In other words, releasing the switch lever 41 from being depressed turns off the switch 11 and then applies a brake.
The grinder 1 according to the first embodiment includes the housing 2 accommodating the motor 4 and extending in the front-rear direction and the switch 11 for driving the motor 4. The grinder 1 also includes the brake assembly 7 including the brake member 32 movable back and forth between the rear braking position, at which a brake is applied to the output shaft 15 in the motor 4, and the front brake release position, at which no brake is applied to the output shaft 15. The grinder 1 also includes the switch lever 41 movable between the initial position at which the switch lever 41 protrudes from the housing 2, and a depressed position at which the switch lever 41 is depressed into the housing 2. The grinder 1 also includes the slide bar 51 (sliding member) slidable between the advanced position (first position) to move the brake member 32 to the brake release position and the retracted position (second position) to move the brake member 32 to the braking position. The grinder 1 also includes the link member 52 rotatable between the right rotational position (first rotational position) to move the slide bar 51 to the advanced position with the switch lever 41 at the depressed position and the left rotational position (second rotational position) to move the slide bar 51 to the retracted position with the switch lever 41 at the initial position. The slide bar 51 turns on the switch 11 at the advanced position and off the switch 11 at the retracted position.
In other words, the slide bar 51 turning on and off the brake assembly 7 turns on and off the switch 11. This structure reduces the number of components and eliminates the likelihood of a cumulative tolerance lowering the operability or causing the brake assembly 7 and the switch 11 to operate at different times. In other words, both the brake assembly 7 and the switch 11 may be operated easily and reliably with a simple structure including fewer components.
The switch 11 is a push switch. The switch 11 includes the plunger 36 protruding rearward and is turned on when the plunger 36 is depressed by the slide bar 51 at the advanced position. In other words, the switch 11 may be easily turned on and off using the slide bar 51. The switch 11 is oriented to have the radially compact design of the rear cover 9, allowing easy gripping.
The slide bar 51 includes, in its rear end, the standing portion 53 for depressing the plunger 36. The plunger 36 is thus reliably depressed as the slide bar 51 advances.
The controller 10 for controlling the motor 4 in response to turning on or off of the switch 11 is located above the switch 11. Thus, the rear cover 9 uses a small space to accommodate the controller 10.
The controller 10 extends laterally in the front-rear direction. This allows the rear cover 9 to accommodate the controller 10 above the switch 11 without increasing the diameter.
When the switch lever 41 is depressed, the brake member 32 moves to the brake release position, and then the switch 11 is turned on. In other words, depressing the switch lever 41 reliably releases a brake before driving the motor 4.
In the first embodiment, the standing portion of the slide bar may be a separate member. The standing portion may also have a different shape. The controller may be positioned or oriented in a manner different from as described above.
Although the link member has the rear arm longer than the front arm in the first embodiment, the rear arm may be shorter than the front arm or both the arms may have the same length. A rear arm longer than a front arm as in the first embodiment will increase the displacement of the front arm when the switch lever is depressed, thus increasing the displacement of the rear arm. This may transfer movement larger than the actual movement of the switch lever to the slide lever, releasing a brake and depressing the plunger reliably. In contrast, a front arm longer than a rear arm may increase the depressing force to the switch lever and then transfer the increased force to the slide bar. This may allow a brake to be released with a small force against an increased urging force from the coil spring for a brake, and improve the operability.
Other embodiments of the present invention will now be described. Similar components as in the first embodiment are indicated by like reference numerals and will not be described repeatedly.
In a grinder 1A shown in
When the switch lever 41 is depressed, the engagement tabs 44 raise the front arm 55 to rotate the link member 52 to the right rotational position as shown in
When the switch lever 41 is released from being depressed, the coil spring 33 urges the brake member 32 back to the braking position. In other words, the brake shoe 34 is pressed against the brake plate 31 to apply a brake on the rotating output shaft 15. At the same time, the brake member 32 slides the slide bar 51 to the retracted position. The slide bar 51 then pulls the rear arm 56 rearward to return the link member 52 to the left rotational position. This causes the upper arm 57 to tilt frontward away from the plunger 36, turning off the switch 11.
The link member 52 according to the second embodiment turns on the switch 11 at the right rotational position (first rotational position) and turns off the switch 11 at the left rotational position (second rotational position).
In other words, the slide bar 51 that turns on and off the brake assembly 7 turns on and off the switch 11 via the link member 52. This structure reduces the number of components and eliminates the likelihood of a cumulative tolerance lowering the operability or causing the brake assembly 7 and the switch 11 to operate at different times. In other words, both the brake assembly 7 and the switch 11 may be operated easily and reliably with a simple structure including fewer components.
The switch 11 includes the plunger 36 protruding frontward. The switch 11 is a push switch and turns on when the plunger 36 is depressed by the link member 52 at the right rotational position. In this manner, the link member 52 easily performs the turning-on or off operation.
The link member 52 includes the upper arm 57 (arm) that depresses the plunger 36 at the right rotational position. This allows the plunger 36 to be reliably depressed as the link member 52 rotates.
The upper arm may have a different shape in the second embodiment. The link member may also include a separate arm member to turn on and off the switch. The front arm and the rear arm may have different lengths.
A grinder 1B shown in
When the switch lever 41 is depressed, the engagement tabs 44 raise the front arm 55 to rotate the link member 52 to the right rotational position as shown in
When the switch lever 41 is released from being depressed, the coil spring 33 urges the brake member 32 back to the braking position. In other words, the brake shoe 34 is pressed against the brake plate 31 to apply a brake on the rotating output shaft 15. At the same time, the brake member 32 slides the slide bar 51 to the retracted position. The slide bar 51 then pulls the rear arm 56 rearward to return the link member 52 to the left rotational position, and at the same time tilts the lever 46 rearward with the engagement hole 58 to turn off the switch 11A.
The slide bar 51 according to the third embodiment turns on the switch 11A at the advanced position and turns off the switch 11A at the retracted position.
In other words, the slide bar 51 that turns on and off the brake assembly 7 turns on and off the switch 11A. This structure reduces the number of components and eliminates the likelihood of a cumulative tolerance lowering the operability or causing the brake assembly 7 and the switch 11A to operate at different times. In other words, both the brake assembly 7 and the switch 11A may be operated easily and reliably with a simple structure including fewer components.
The switch 11A includes the lever 46 protruding downward. The switch 11A is a toggle switch and is turned on when the lever 46 is swung by the slide bar 51 at the advanced position. In this manner, the slide bar 51 may easily perform the turning-on or off operation.
The controller 10 is located on the right of the switch 11A. Thus, the rear cover 9 uses a small space to accommodate the controller 10 when the toggle switch is used.
The controller 10 extends vertically in the front-rear direction. This allows the rear cover 9 to accommodate the controller 10 beside the switch 11A without increasing its diameter.
In the third embodiment, the slide bar may engage with the lever of the switch using a recess formed on the slide bar, instead of using the engagement hole.
The controller may be located on the left of the switch, instead of on the right. The front arm and the rear arm may have different lengths.
Modifications common to the embodiments will now be described.
The switch lever may be formed on the top surface or the side surface of the housing instead of on the lower surface. In this case, the sliding member and the link member may also be located on the upper surface or the side surface together with the switch lever. The switch may be oriented differently.
Although a brake is released at the advanced position of the sliding member and a brake is applied at the retracted position of the sliding member, a different brake assembly may be used. A brake may be released at the retracted position (first position) of the sliding member, and a brake may be applied at the advanced position (second position) of the sliding member.
The switch lever may swing about the rear end, instead of about the front end.
The motor may be a brushless motor. The controller may be at a different location.
The grinder may not be powered by alternating current (AC) but may be powered by direct current (DC) from a battery pack attached on the rear end of the housing.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-175940 | Sep 2019 | JP | national |
