34, and drive power of the motor 44 is transmitted to the spindle 34 by the bevel gear 52. The motor 44 is electrically connected to a control unit, which is not shown in the figure, and the motor 44 is driven by the control unit.

Switch Mechanism 60

As shown in FIG. 1 and FIG. 3 to FIG. 6, the switch mechanism 60 is configured as a mechanical portion to switch the motor 44 to drive or stop state. The switch mechanism 60 comprises the switch 62, the slide bar 64 as a switching portion, the switch lever 66 as an operating portion, and the motor stop lever 68 as a stop portion. The motor stop lever 68 is connected to a suspension device 72 and the switch 62 and is part of a transmission mechanism (transmission member) that is displaced by the force received by the suspension device 72. The transmission mechanism also includes a coupling ring 74 that connects the suspension device 72 and the motor stop lever 68. The motor stop lever 68 itself may be used as the transmission mechanism in the present invention.

Switch 62

The switch 62 is housed in the tail cover 22 and held by the switch holding portion 26 of the motor housing 24. The switch 62 comprises a substantially rectangular block-shaped switch body 62A and a plunger 62B protruding rearwardly from the switch body 62A. The switch body 62A is housed in the switch housing portion 26A of the switch holding portion 26, and the plunger 62B is disposed at the rear portion of the switch housing portion 26A. When the plunger 62B is pressed toward the front, the switch 62 is switched from an OFF state to an ON state. The switch 62 is electrically connected to the control unit, and outputs an output signal to the control unit according to a pressured state on the plunger 62B by the slide bar 64, which is described below, and the motor 44 is switched to the drive or stop state by the control unit. The switch body 62A contains a mechanism (e.g., spring) that forces the plunger 62B backward, and the plunger 62B is constantly being pushed backward. Therefore, when the plunger 62B is pressed forward, it must be pressed forward against backward force applied to the plunger 62B.

Slide Bar 64

The slide bar 64 is formed in the form of a substantially long plate that extends in the front-back direction and has the left-right direction as thickness direction. The slide bar 64 is housed in a left end of the inside of the housing cylinder portion 28 and the tail cover 22, and is disposed adjacent to the inner circumference of the housing cylinder portion 28 and the tail cover 22. In detail, the front end portion of the slide bar 64 is disposed on the right side of the lever attachment portion 28B of the housing cylinder portion 28, and the rear end portion of the slide bar 64 is disposed on the front side of the lever guide portion 22A of the tail cover 22. The front end portion of the slide bar 64 is slidably coupled to the housing cylinder portion 28 in the front-back direction by the switch lever 66 described further below, and the rear end portion of the slide bar 64 is supported in the front-back direction by the switch holding portion 26 of the motor housing 24. Specifically, the slide bar 64 is configured to be able to move between an OFF position (position shown in FIG. 3) and an ON position (position shown in FIG. 6), which is moved forward from the OFF position. The following description assumes that the slide bar 64 is positioned in the OFF position.

A lever coupling portion 64A is formed at the front end portion of the slide bar 64 for coupling the switch lever 66 described further below. The lever coupling portion 64A is positioned offset to the left side with respect to the slide bar 64. A coupling hole 64B is formed through the lever coupling portion 64A, and the coupling hole 64B is formed in a substantially C-shape open to the rear side when viewed from the left side.

A supported portion 64C, which is supported by the motor stop lever 68 described further below, is formed at the rear end portion of the slide bar 64. The supported portion 64C is positioned offset to the right side relative to the slide bar 64, and the front end portion of the supported portion 64C is formed in the substantially crank shape in plan view and connected to the slide bar 64. The switch pressure portion 64D is integrally formed at the rear end portion of the supported portion 64C. The switch pressure portion 64D is formed in the substantially rectangular plate shape with the front-back direction as the thickness direction and the left-right direction as the longitudinal direction, and extends from the supported portion 64C to the right side. A tip (right end) portion of the switch pressure portion 64D is inserted from the left side within the rear portion of the switch housing portion 26A of the switch holding portion 26 and is supported by the switch housing portion 26A, slidable in the front-back direction. The tip of the switch pressure portion 64D is disposed adjacent to the rear side of the plunger 62B of the switch 62. When the slide bar 64 slides from the OFF position to the ON position, the plunger 62B is pressed by the switch pressure portion 64D and the switch 62 is switched from the OFF state to the ON state. A chamfer portion 64E is formed at a corner portion that is a connection portion between the supported portion 64C and the switch pressure portion 64D.

A spring housing portion 64F is formed in the middle portion of the left side of the slide bar 64 in the front-back direction. The spring housing portion 64F is formed in a concave shape open to the left side and in a substantially rectangular shape with the front-back direction as the longitudinal direction when viewed from the left side. The spring housing portion 64F houses a return spring 70 configured as a compression coil spring. The front end portion of the return spring 70 is engaged with the rear end surface of the housing cylinder portion 28, and the rear end portion of the return spring 70 is engaged with a rear surface of the spring housing portion 64F. The return spring 70 forces the slide bar 64 toward the rear side (OFF position side).

Switch Lever 66

The switch lever 66 is formed in the shape of the substantially crank-shaped plate in cross-sectional view from upper side. The switch lever 66 is disposed on the left side of the lever attachment portion 28B of the motor housing 24 and between the upper and lower pairs of engagement ribs 28E, and is attached on the lever attachment portion 28B, movable in the front-back direction. A coupling shaft 66A protruding to the right is integrally formed in the rear portion of the switch lever 66. The coupling shaft 66A is formed in a substantially T-shape when viewed from the front-back direction, and the tip of the coupling shaft 66A protrudes to both sides in the up-down direction. The middle portion of the coupling shaft 66A in the left-right direction is inserted into the attachment hole 28C of the lever attachment portion 28B, slidable in front-back direction. The middle portion of the coupling shaft 66A in the left-right direction inserts through the coupling hole 64B of the slide bar 64, and the slide bar 64 and the switch lever 66 are coupled so that they can move together in the front-back direction. In other words, the switch lever 66 is configured to be slidable between the OFF position and the ON position together with the slide bar 64. In the OFF position of the switch lever 66, the coupling shaft 66A contacts the inner circumference of the attachment hole 28C in the motor housing 24 to hold the switch lever 66 and the slide bar 64 in the OFF position.

Portions protruding to both sides in the up-down direction at the tip of the coupling shaft 66A are configured as a fulcrum portion 66B (see FIG. 5). The fulcrum portion 66B is formed in a substantially semicircular shape convex to the left when viewed from the upper side, and is disposed adjacent to the right side of the lever coupling portion 64A of the slide bar 64. This restricts a movement of the switch lever 66 to the left side. A hook portion 66C bent to the right is formed at the front end portion of the switch lever 66, and the hook portion 66C contacts the rear end portion of the plate portion 28D of the motor housing 24. The force of the return spring 70 is transmitted to the coupling shaft 66A, and the switch lever 66 is held slightly inclined to the right side toward the front in plan view. The switch lever 66 is configured to be pivotable with the fulcrum portion 66B as a fulcrum. Specifically, by pressing the rear end portion of the switch lever 66 to the right, the switch lever 66 pivots with the fulcrum portion 66B as the fulcrum, and the hook portion 66C is displaced to the left. Then, by sliding the switch lever 66 to the ON position while pivoting it, the hook portion 66C is disposed in front of and engages the engagement rib 28E. As a result, the ON position of the switch lever 66 and the slide bar 64 is maintained. In other words, the switch 62 is maintained in the ON state (hereinafter referred to as an ON-lock state). The hook portion 66C and the engagement rib 28E are part of an ON-lock mechanism that enables the switch lever 66 to be held in the ON position (switch 62 in the ON state) even when operating force is released.

Motor Stop Lever 68

The motor stop lever 68 is provided on the tail cover 22 and constitutes a coupling member that couples the suspension device 72 to the tail cover 22 (grinder 10). As mentioned above, the motor stop lever 68 is also a member (or mechanism) connecting the suspension device 72 and the switch 62. The motor stop lever 68 is formed in the form of the substantially long plate that extends in the front-back direction and has the left-right direction as the thickness direction. The motor stop lever 68 is housed in the lever guide portion 22A of the tail cover 22, movable in the front-back direction and is inserted in the communicating hole 22B, movable in the front-back direction. In detail, the motor stop lever 68 is configured to be movable between an initial position (the position shown in FIG. 1, FIG. 3, and FIG. 6) and a withdrawn position (the position shown in FIG. 7), which is moved rearward from the initial position. In a normal state, the motor stop lever 68 is positioned in the initial position, and when a tensile force to the rear side is received from the suspension device 72, the motor stop lever 68 is withdrawn to the rear side and slides to the withdrawn position. In the present invention, the initial position and the withdrawn position may be rephrased as an initial state and an operating state, respectively.

A pair of upper and lower stopper portions 68A are formed at the front end portion of the motor stop lever 68, and the stopper portions 68A protrude to both sides of the motor stop lever 68 in the up-down direction. The rear surface of the stopper portions 68A is formed along a surface orthogonal to the front-back direction. An inclined surface 68B is formed on the right side of the front end portion of the motor stop lever 68. The inclined surface 68B is inclined to the left side toward the front side in the plan view from the upper side.

In the initial position of the motor stop lever 68, the front portion of the motor stop lever 68 is disposed adjacent to the left side of the supported portion 64C of the slide bar 64, supporting the motor stop lever 68 from the left side. In other words, the motor stop lever 68 is configured as the member that limits the movement of the rear end portion of the slide bar 64 to the left side and maintains a posture of the slide bar 64. Thickness of the motor stop lever 68 is substantially equal to an offset amount to the right side of the supported portion 64C of the slide bar 64.

In the withdrawn position of the motor stop lever 68, it is set so that a support state of the slide bar 64 against the supported portion 64C by the motor stop lever 68 is released (see FIG. 7). In other words, in the withdrawn position of the motor stop lever 68, it is set to allow the supported portion 64C to move to the left side. As will be described in detail further below, it is set so that when the motor stop lever 68 is moved to the withdrawn position with the slide bar 64 positioned in the ON position, the pressure of the plunger 62B of the switch 62 on the switch pressure portion 64D changes the posture of the slide bar 64 so that the rear end portion of the slide bar 64 is displaced to the left side, and the switch pressure portion 64D is released from its pressured state. In the withdrawn position of the motor stop lever 68, the rear surface of the stopper portion 68A of the motor stop lever 68 contacts the stopper surface 22C of the tail cover 22 to prevent the motor stop lever 68 from being withdrawn rearward from the communicating hole 22B of the tail cover 22. Furthermore, in the withdrawn position of the motor stop lever 68, the tip of the inclined surface 68B of the motor stop lever 68 is set to overlap the chamfer portion 64E of the slide bar 64 in the OFF position in the front-back direction (see FIG. 7).

A suspension coupling portion 68C is formed at the rear end portion of the motor stop lever 68, and the suspension coupling portion 68C protrudes from the motor stop lever 68 to the left side. A suspension hole 68D is formed through the suspension coupling portion 68C in the up-down direction. The coupling ring 74 of the suspension device 72 is inserted into the suspension hole 68D, and the suspension device 72 is coupled to the motor stop lever 68. One end portion of a strap, not shown, is inserted into the suspension device 72, and other end portion of the strap is fixed to a hanging member when the grinder 10 is being used. When the grinder 10 is removed from an operator's hand, the grinder 10 is suspended by the strap to prevent the grinder 10 from falling to ground. It may be configured so that said one end portion of the strap, not shown, is directly inserted into the suspension coupling portion 68C, i.e., the motor stop lever 68 may be configured to serve as the suspension device.

Operation and Effect

Next, the operation and effects of the grinder 10 of the present embodiment will be described.

During processing with the grinder 10 configured as described above, the operator grips the housing cylinder portion 28 of the motor housing 24 and the tail cover 22. Then, by the operator's sliding the switch lever 66 from the OFF position to the ON position, the slide bar 64 slides from the OFF position to the ON position together with the switch lever 66. As a result, the switch pressure portion 64D of the slide bar 64 presses the plunger 62B of the switch 62 toward the front, causing the switch 62 to switch from the OFF state to the ON state. As a result, the control unit drives the motor 44, and the spindle 34 and the grindstone 40 rotates. Thus, the grinder 10 can apply grinding processing. In the ON position of the switch lever 66, the hook portion 66C of the switch lever 66 engages the engagement rib 28E of the motor housing 24, and the grinder 10 is in the ON-lock state. To release the ON-lock state of the grinder 10, the operator pushes the rear end of the switch lever 66 in the right direction, which causes the switch lever 66 to pivot (rotate) in a counterclockwise direction when viewed from the upper side. As a result, the hook portion 66C and the engagement rib 28E are disengaged and the ON-lock state is released.

In working with the grinder 10, the operator holds the grinder 10 by hand. Here, the grinder 10 has the motor stop lever 68 coupled to the suspension device 72. Therefore, if the grinder 10 were to fall away from the operator's hand, the strap fixed to the suspension device 72 would cause the grinder 10 to be suspended. This prevents the grinder 10 from falling to the ground.

Since a center of gravity of grinder 10 is set around motor 44, when the grinder 10 is in the suspended state, the grinder 10 is suspended so that the front side of grinder 10 faces vertically downward, and a tensile force acts on the motor stop lever 68 to the rear side (vertically upward). This tensile force withdraws the motor stop lever 68 from the initial position to the withdrawn position. As a result, the support state of the motor stop lever 68 to the supported portion 64C of the slide bar 64 is released.

Here, the switch pressure portion 64D of the slide bar 64 extends from the supported portion 64C to the right side, and the tip of the switch pressure portion 64D presses the plunger 62B of the switch 62 toward the front side. Therefore, in the ON position of the slide bar 64, a reaction force acting from the plunger 62B to the switch pressure portion 64D causes a clockwise rotational moment to act on the tip of the switch pressure portion 64D in the plan view (see arrow A in FIG. 6). In other words, a force is acting on the supported portion 64C, which is the rear end of the slide bar 64, to displace the supported portion 64C to the left.

In the suspended state of the grinder 10, as described above, the motor stop lever 68 is withdrawn to the withdrawn position to release the support state of the slide bar 64 to the supported portion 64C by the motor stop lever 68. Therefore, displacement of the supported portion 64C to the left side is permitted. As a result, in the suspended state of the grinder 10, the posture of the slide bar 64 is changed so that the rear end portion of the slide bar 64 is displaced (warped) to the left side, and the pressured state on the switch 62 by the switch pressure portion 64D is released (see FIG. 7). As a result, the switch 62 is switched from the ON state to the OFF state, and the drive of the motor 44 is stopped.

When the posture of the slide bar 64 is changed so that the rear end portion of the slide bar 64 is warped to the left side, the front end portion of the slide bar 64 is displaced to the right side. This causes the lever coupling portion 64A of the slide bar 64 to pull the coupling shaft 66A of the switch lever 66 to the right side, causing the rear end portion of the switch lever 66 to pivot so that the rear end portion of the switch lever 66 is displaced to the right side (by being forced in the right direction). In other words, the switch lever 66 pivots counterclockwise when viewed from the upper side. The movement of the switch lever 66 at this time (counterclockwise pivot) is similar to the above-mentioned movement during the ON-lock release operation by the operator. As a result, an engagement state between the hook portion 66C of the switch lever 66 and the engagement rib 28E of the housing cylinder portion 28 is released. In other words, the ON-lock state of the grinder 10 is released. Therefore, the slide bar 64 and the switch lever 66 slide from the ON position to the OFF position by the force of the return spring 70. At this time, the chamfer portion 64E at the rear end of the slide bar 64 is disposed to the right of the tip of the inclined surface 68B of the motor stop lever 68.

By pushing the motor stop lever 68 forward from the withdrawn position to the initial position, the motor stop lever 68 is returned to the initial position, and the supported portion 64C of the slide bar 64 is supported from the left side by the front portion of the motor stop lever 68. When the motor stop lever 68 is slid from the withdrawn position to the front side, the inclined surface 68B of the motor stop lever 68 contacts the chamfer portion 64E of the slide bar 64, which forces the rear end of the slide bar 64 to the right side, and the motor stop lever 68 is inserted between the supported portion 64C of the slide bar 64 and the tail cover 22. The inclined surface 68B or the chamfer portion 64E serves as a guide when returning the motor stop lever 68 to the initial position.

As described above, in the grinder 10, the switch 62 is switched from the OFF state to the ON state by moving slide bar 64 in housing 20 from the OFF position to the ON position. Here, the motor stop lever 68 is movably provided in the housing 20, and the motor stop lever 68 is configured to be able to be coupled to the suspension device 72. The motor stop lever 68 moves from the initial position to the withdrawn position when a rearward tensile force is received from the suspension device 72. At this time, the supported portion 64C of the slide bar 64 in the ON position moves to the left side, and the switch 62 switches from the ON state to the OFF state. Specifically, in the withdrawn position of the motor stop lever 68, a posture-maintaining state of the motor stop lever 68 with respect to the slide bar 64 in the ON position is released, the posture of the slide bar 64 is changed, and the switch 62 is switched from the ON state to the OFF state. Thus, while the grinder 10 is in the suspended state, the drive of the motor 44 is stopped and the grinder 10 can be placed in the non-operating state. When the grinder 10 is in the suspended state, the supported portion 64C of the slide bar 64 is moved to the left side (retreated state), so the switch 62 cannot be turned on even if the slide bar 64 is moved back and forth. In other words, activation of the motor 44 is also restricted in the grinder 10 in the suspended state.

The switch lever 66 is operably provided in the housing cylinder portion 28, and the switch lever 66 is coupled to the slide bar 64 in an integrally movable manner. In the ON position of the switch lever 66, the hook portion 66C of the switch lever 66 engages the engagement rib 28E of the housing cylinder portion 28, holding the switch lever 66 and the slide bar 64 in the ON position. This allows the grinder 10 to be in the ON-lock position for working. Furthermore, when the motor stop lever 68 is moved to the withdrawn position, the engagement state between the switch lever 66 and the engagement ribs 28E is released as described above. This allows the motor 44 in the driven state to be stopped and the switch lever 66 and the slide bar 64 to be returned to the OFF position when the grinder 10 is placed in the suspended state.

In the slide bar 64, the switch pressure portion 64D extends from the rear end portion of the supported portion 64C to the right side, and the switch 62 is switched to the ON state when the switch pressure portion 64D presses the plunger 62B of the switch 62 to the front side. The motor stop lever 68 is disposed adjacent to the left side of the supported portion 64C to support the supported portion 64C and maintain the posture of the slide bar 64. In the withdrawn position of the motor stop lever 68, the posture-maintaining state of the slide bar 64 at the motor stop lever 68 is released. In the withdrawn position of the motor stop lever 68, the reaction force acting on the switch pressure portion 64D from the plunger 62B of the switch 62 displaces the supported portion 64C of the slide bar 64 in the ON position to the left side to release the pressured state on the switch 62 by the slide bar 64.

The motor stop lever 68 is coupled to the tail cover 22, movable in the front-back direction. The front portion of the motor stop lever 68 is disposed between the tail cover 22 and the supported portion 64C of the slide bar 64 to support the supported portion 64C. This allows the slide bar 64 to be supported by the motor stop lever 68 while preventing the supported portion 64C from being exposed to the outside. Thus, the posture of the slide bar 64 can be maintained by the motor stop lever 68 while the tail cover 22 provides protection to the slide bar 64. The rear end portion of the motor stop lever 68 has the suspension coupling portion 68C that is exposed to the outside of the tail cover 22. This allows the coupling ring 74 of the suspension device 72 to be inserted into the hole 68D of the suspension coupling portion 68C, thereby coupling the motor stop lever 68 and the suspension device 72.

The front end portion of the motor stop lever 68 is provided with the pair of upper and lower stopper portions 68A. In the withdrawn position of the motor stop lever 68, the stopper portions 68A contact the stopper surface 22C of the tail cover 22 to restrict the movement of the motor stop lever 68 to the rear side. This prevents the motor stop lever 68 from falling off the tail cover 22.

The inclined surface 68B is formed on the right side of the front end portion of the motor stop lever 68, and the inclined surface 68B slopes to the left toward the front side in plan view. This allows the motor stop lever 68 to be disposed adjacent to the left side of the slide bar 64 by pushing the supported portion 64C of the slide bar 64 up to the right side by the inclined surface 68B when the motor stop lever 68 in the withdrawn position is moved to the front side.

Moreover, in the OFF position of the slide bar 64 and in the withdrawn position of the motor stop lever 68, the chamfer portion 64E of the slide bar 64 is positioned to overlap the inclined surface 68B of the motor stop lever 68 in the front-back direction. Therefore, when the motor stop lever 68 in the withdrawn position is moved to the front, the motor stop lever 68 can be moved to the front while preventing the motor stop lever 68 from being caught on the slide bar 64. In other words, in the grinder 10 (the present invention), by returning the motor stop lever 68, which is in the withdrawn position after being pulled, to the initial position, the start and stop of the motor 44 can be controlled again by operation of the switch lever 66 (switch 62) by the operator. Since the grinder 10 is configured so that the ON-lock mechanism is released when the grinder is suspended, it is also possible to suppress unintentional restarting of the motor 44 when the motor stop lever 68 is returned to the initial position. The motor stop lever 68 may be configured so that it is always pushed forward by an elastic body such as a spring. In such a case, the elastic body (spring) for restoring the motor stop lever 68 to its initial position may be configured to extend when it is suspended (when it receives the weight of the grinder 10) and to compress or not extend when it is not suspended (when the load received is less than the weight of the grinder 10).

Variant 1 of the Switch Mechanism 60

Next, FIG. 8 and FIG. 9 are used to describe Variation 1 of the switch mechanism 60. In FIG. 8 and FIG. 9, members that are similarly configured to the present embodiment are marked with the same symbols. In Variation 1 of the switch mechanism 60, a support frame 80 is added as a switch support member. The support frame 80 is formed in the form of a substantially U-shaped frame open to the front, when viewed from the upper side, and is slidable in the front-back direction on the switch holding portion 26 of the housing 20. Specifically, the support frame 80 is configured to be movable between a normal position (position shown in FIG. 9A) and a separated position (position shown in FIG. 9B), which is moved forward from the normal position. The switch 62 is supported by the support frame 80 and is configured to be movable between the normal position and the separated position integrally with the support frame 80. Furthermore, the left side of the support frame 80 is inserted through a first hole 64G formed in the switch pressure portion