GB2496722A - Hammer drill switch with dust discharge hole - Google Patents

Abstract

The hammer drill (1, Figure 1) includes a rotatable portion that is capable of selecting at least two operation modes by slidingly operating a clutch provided in a housing (2, figure 1) using a switching lever 11 from outside the housing. A grip portion 13 of the switching lever is provided with a bottomed hole 16 that houses a lock button 17. The grip portion is provided with a communication hole 25 that communicates between the bottomed hole and the outside of the grip portion. The hole is capable of discharging dust that has entered into the grip portion. The hole may be formed along the direction of protrusion and depression of the lock button. The hole may be formed as a pair of slits with an elongated rectangular shape. The slit may be tapered in shape.

Description

The present invention relates to a hammer drill on which at least two operation modes

are selectable.

A hammer drill is provided with a clutch that is disposed between a rotating mechanism and a hammering mechanism that are installed inside a housing, and the clutch can be selectively linked to both the mechanisms. By switching a slide position of the clutch from outside the housing, it is possible to select a plurality of operation modes, such as a drill mode in which a bit that is held on a leading end of the housing is caused to rotate only, a hammer drill mode in which the bit is hammered in addition to being rotated, and a hammer mode in which the bit is hammered only.

A switching lever is used to switch the slide position of the clutch. As disclosed in Japanese Patent Application Publication No. JP2004-167638A, for example, a switching lever including a rotating portion, a grip portion and a lock button is known. The rotating portion is rotatably held on the housing and engages with the clutch. The grip portion is provided contiguously to the rotating portion on the outer side of the housing, and formed in a radiating direction from a center of rotation of the rotating portion. The lock button can protrude from and be depressed into a bottomed hole that is provided in the grip portion. The lock button is housed in the grip portion such that it is urged in a direction of protrusion from the grip portion, and engages with a guide groove that is provided on the outer surface of the housing. Engagement recesses are provided successively in the guide groove. At switching positions of the grip portion corresponding to the operation modes, the lock button protrudes further and is engaged by each of the engagement recesses.

Therefore, when switching between the operation modes, the lock button is pushed inside the grip portion, thus releasing the engagement with the engagement recess in that position. Then, while continuing to press in the lock button, the grip portion is rotated to the switching position corresponding to the desired operation mode. In the corresponding switching position, the lock button once more protrudes and engages with the engagement recess, thus applying the desired operation mode.

However, with the above-described switching mechanism, due to the structure in which the lock button housed in the grip portion protrudes and is depressed, sometimes dust can enter into the bottomed hole from a gap between the lock button and the grip portion. If this dust accumulates inside the bottomed hole, slidability of the lock button deteriorates and there is a risk that it becomes difficult to push in the lock button, or that the lock button does not completely protrude in the position of the engagement recess.

In light of the foregoing, it is an aim of the present invention to provide a hammer drill in which slidability of a lock button can be maintained and ease of use is not compromised even when dust entcrs inside a grip portion.

In order to achieve the above-described object, according to a first aspect of the invention, a communication hole is provided in a grip portion, the communication holc communicating betwccn a bottomed hole housing a lock button and the outsidc of the grip portion and allowing dust that has entered inside the grip portion to be discharged.

A second aspcct of the invention is structured such that, in the configuration of the first aspect, the communication hole is formed along the direction of protrusion and depression of the lock button.

A third aspect of the invention is structured such that, in the configuration of the first or second aspect, the communication hole is formed as a pair.

A fourth aspect of the invention is structured such that, in the configuration of any one of the first to third aspects, a plurality of engagement recesses are successively formed in the guide groove, and an engaging portion of the lock button engages with the engagement recesses in the direction of protrusion, at switching positions of the operation modes. The engaging portion and the engagement recesses have a tapered shape, in which they taper in the direction of protrusion.

According to the first aspect of the invention, as the grip portion of a switching lever is provided with the communication hole that can discharge infiltrated dust, it is possible to maintain slidability of the lock button and provide superior usability, even when dust has entered into the grip portion from a gap betwccn the lock button and the grip portion.

According to the second aspect of the invention, in addition to the effects of the first aspect, it is possible to enhance the effect of discharging the dust by the communication hole as a result of guiding the dust that has entered inside the grip portion to the communication hole by the operation of depressing the lock button.

According to the third aspect of the invention, in addition to the effects of the first and second aspects, it is possible to evenly and efficiently discharge the dust by providing the communication hole as a pair.

According to the fourth aspect of the invention, in addition to the effects of the first to third aspects, it is possible to inhibit looseness of the lock button at the switching position of the opcration mode, and reliably determine the position of the grip portion.

Hereinafter, exemplary embodiments of the present invention will be explained with reference to the appended drawings, in which: FIG. lisa side view of a hammer drill.

FIG. 2 isa cross-sectional view along a line A-A shown in FIG. 1.

FIG. 3 is a cross-scctional vicw along a line B-B shown in FIG. 1.

FIG. I is a general view showing an example of a hammer drill 1 and FIG. 2 is a cross-sectional view along a line A-A shown in FIG. 1. The hammer drill 1 has a known structure in which a tool holder 3 protrudes to the front (the left side in FIG. 1) of a housing 2 that houses a motor (not shown in the drawings), the tool holder 3 being provided with a chuck 4 to which a bit can be detachably attached. A rotating mechanism that rotates the tool holder 3, and a hammering mechanism that hammers the bit are installed inside the housing 2. A reference numeral 5 refers to a handle that is formed to the rear of the housing 2 and that has a switching lever 6, and a reference numeral 7 refers to a battery pack that is a power source attached to a lower portion of the handle 5.

The rotating mechanism is structured such that a gear is externally and rotatably attached to a counter shaft 8. The counter shaft 8 is disposed below and in parallel to the tool holder 3, and the gear on the counter shaft 8 meshes with a gear provided on the tool holder 3. Further, the hammering mechanism is structured such that, behind the gear, an arm is coupled to a boss sleeve which is externally attached to the counter shaft 8, the arm being coupled to the boss sleeve via a swash bearing. The arm is coupled to a piston cylinder 9 that is inserted inside the tool holder 3. Inside the piston cylinder 9, a striker is attached such that the striker can move in the front-rear direction via an air chamber. The striker can strike an impact bolt that is provided to the front of the striker. The rotating mechanism and the hammering mechanism are known mechanisms.

In addition, a clutch 10 is externafly attached to the counter shaft 8 between the gear and the boss sleeve, such that the clutch 10 can slide along the counter shaft 8. The clutch 10 is provided, at both ends, with engaging tabs that engage with the gear and the boss sleeve.

Various operation modes can be selected by selecting a slide position of the clutch 10.

Specifically, by selecting one of a forward position in which the clutch 10 engages with the gear only, a rearward position in which the clutch 10 engages with the boss sleeve only, and an intermediate position in which the clutch 10 engages simultaneously with the gear and the boss sleeve, it is possible to select between a drill mode, a hammer mode and a hammer drill mode. In the drill mode, the tool holder 3 rotates via the gear and causes the bit to rotate. In the hammer mode, the piston cylinder 9 is caused to reciprocate by rocking of the arm and the bit is hammered via the impact bolt being struck by the striker coupled to the piston cylinder 9. In the hammer drill mode, the rotation of the tool holder 3 and the hammering of the impact bolt are performed simultaneously The slide position of the clutch 10 can be selected by a switching lever 11 that is provided on the housing 2. The switching lever 11 has a rotating portion 12 that is rotatably fitted to the housing 2, and a grip portion 13 that is contiguously formed on the outer side of the rotating portion 12 (the outer side of the housing 2) in a direction radiating from a center of rotation of the rotating portion 12. An engagement pin 14, which is urged to protrude toward an inner side of the housing 2 by a coil spring 15 and which engages with the clutch 10, is provided on the rotating portion 12 in a position that is eccentric relative to the center of rotation. Specifically, the eccentric movement of the engagement pin 14 as a result of the rotation of the rotating portion 12 causes the clutch 10 to move to the left and to the right.

Meanwhile, a bottomed hole 16 that is open at one end is formed in the grip portion 13, and a lock button 17 is provided inside the bottomed hole 16. As shown in FIG. 3, the lock button 17 is provided such that it can fit with the bottomed hole 16 and slide along the bottomed hole 16. At the same time, the lock button 17 is urged in a direction to protrude from the grip portion 13 by a coil spring 18 that is provided between the lock button 17 and the bottom of the bottomed hole 16.

It should be noted that the engaging portion 19 is provided on the outer surface of the lock button 17 on the side of the housing 2, and the engaging portion 19 engages with an arc-shaped guide groove 20 that is formed in the outer surface of the housing 2 centering around the rotating portion 12. The position of protrusion of the lock button 17 is thus regulated. Further, three engagement recesses 21 to 23 are formed on the outer peripheral side (the side in the direction of protrusion of the lock button 17) of the guide groove 20 such that they each protrude in a successive state from the guide groove 20. The engagement recesses 21 to 23 regulate the rotation of the grip portion 13 at each of the switching positions of the various operation modes at which the engaging portion 19 is engaged. Here the engagement recess 21 is the switching position of the drill mode, the engagement recess 22 is the switching position of the hammer drill mode, and the engagement recess 23 is the switching position of the hammer mode.

Note that, in the hammer mode, a lock member 24 that is provided inside the housing 2 engages with the gear on the counter shaft 8 and regulates the rotation of the gear, and thus the rotation of the tool holder 3 and the bit is locked. However, in a switching position between the hammer mode and the hammer drill mode, a pressing portion (not shown in the drawings) that is provided on the rotating portion 12 causes the lock member 24 to separate from the gear, and thus a neutral mode is established in which the rotation of the tool holder 3 and the bit is free.

Here, each of the engagement recesses 21 to 23 has a tapered shape in which a width in the left-right direction becomes gradually narrower from the side that is contiguous with the guide groove 20 toward the side of protrusion. The engaging portion 19 that engages with the engagement recesses 21 to 23 also has a tapered shape in which a width in the left-right direction becomes gradually narrower in the direction of protrusion, matching the taper of the engagement recesses 21 to 23.

Further, in the grip portion 13, a pair of slits 25 is penetratingly formed in a side surface on the bottom surface side of the bottomed hole 16. The slits 25 are communication holes that communicate between the bottomed hole Th and the outside of the grip portion 13, and each of the slits 25 has an elongated rectangular shape in a cross section. The slits 25 are formed on both the eft and right sides of the coil spring 18 and are formed in parallel with the direction of protrusion and depression of the lock button 17. The slits 25 have a tapered shape in which an opening becomes larger in a width direction from the side that communicates with the outside of the grip portion 13 toward the side that communicates with the bottomed hole 16.

With the hammer drill 1 structured in the manner described above, when changing from, for example, the hammer drill mode shown in FIG. 3 to another of the operation modes, when the lock button 17 is pushed into the inside of the bottomed hole 16 against the urging force of the coil spring 18, the engaging portion 19 is separated from the engagement recess 22 and is allowed to rotate along the guide groove 20. Thus, in this state, the grip portion 13 can be rotated to the position of the engagement recess 21 or the position of the engagement recess 23. When the grip portion 13 reaches the position of the engagement recess 21 or the engagement recess 23, the lock button 17 protrudes due to the urging force of the coil spring 18. Then, the desired operation mode is applied as a result of the engaging portion 19 being engaged with the engagement recess 21 or the engagement recess 23.

At that time, the engaging portion 19 fits with the engagement recess 21 or the engagement recess 23 due to their mutually left-to-right tapered shapes. Thus, in combination with the lock button 17 being urged to protrude, there is no looseness of the lock button 17 in the rotation direction, and the grip portion 13 can be reliably held.

Then, even if dust that arises in operation enters into the bottomed hole 16 from the gap between the grip portion 13 and the lock button 17, as the grip portion 13 is provided with the slits 25 that communicate between the bottom portion of the bottomed hole 16 and the outside of the grip portion 13, the dust is discharged to the outside of the grip portion 13 via the slits 25, due to the operation of depressing the lock button 17, for example. As a result, it becomes difficult for dust to accumulate inside the bottomed hole 16. Further, abnormalities, in which it is difficult to push in the lock button 17 or in which the lock button 17 does not fully protrude at the positions of the engagement recesses 21 to 23, do not occur. In particular, as the opening of the slits 25 is wider on the side of the bottomed hole 16, the dust is easily guided to the slits 25 and accumulation of dust inside the bottomed hole 16 is effectively inhibited.

In this way, according to the hammer drill I of the above-described embodiment, as the grip portion 13 is provided with the slits 25 that communicate between the bottomed hole 16 and the outside of the grip portion 13 and that can discharge the dust that enters inside the grip portion 13. Thus, the slidability of the lock button 17 can be maintained even if dust enters inside the grip portion 13 from the gap between the lock button 17 and the grip portion 13 of the switching lever 11. Superior usability is therefore provided.

Particularly, here, the slits 25 are formed along the direction of protrusion and depression of the lock button 17, and thus, the dust that has entered inside the grip portion 13 is guided to the side of the slits 25 by the operation of depressing the lock button 17.

As a result, the effect of discharging the dust from the slits 25 can be further enhanced.

In addition, by forming the slits 25 as a pair, the dust can be discharged both evenly and effectively.

Furthermore, the plurality of engagement recesses 21 to 23 are provided successively in the guide groove 20, and the engaging portion 19 of the lock button 17 is engaged with the engagement recesses 21 to 23 in the direction of protrusion, at the switching positions of the operation modes. The engaging portion 19 and each of the engagement recesses 21 to 23 have a tapered shape, in which they taper in the direction of protrusion, thus inhibiting looseness of the lock button 17 at the operation mode switching position. It is therefore possible to reliably determine the position of the grip portion 13.

It should be noted that the communication holes are not limited to being a pair, and there may be three or more communication holes, or, alternatively, there may be one communication hoLe. Further, the communication holes need not necessarily be tapered and the opening may have the same size on the bottomed hole side and on the outside.

Additionally, the communication hole is not limited to the elongated rectangular shape in the cross section, and can be changed as applicable, having, for example, a circular or elliptical shape or a square shape etc. in the cross section.

Furthcrmore, the position in which the communication hole is provided is not limitcd to the side of the bottom surface of the bottomed hole in the grip portion, and can be provided in a side surface that intersects with the direction of protrusion and depression of the lock button, or can be provided in a plurality of side surfaces.

Furthermore, the engaging portion of the lock button and the engagement recess need not necessarily have a tapered shape. Also, the operation modes need not be the four selectable operation modes (including the neutral mode) as in the above-described embodiment. For example, the present invention can be applied as long as the hammer drill can select between at least two operation modes, such as the three operation modes without the neutral mode, and so on. It goes without saying that the rotating mechanism and the hammering mechanism are also not limited to those of the above-described embodiment.

It is explicitly stated that all features discloscd in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure as well as for the purpose of restricting the claimed invention independent of the composition of the features in the embodiments and/or the claims. It is explicitly stated that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure as well as for the purpose of restricting the claimed invention, in particular as limits of value ranges.

Claims (1)

1. <claim-text>CLAIMS: 1. A hammer drill comprising: a rotating portion that is capable of selecting between at least two operation modes, by slidingly operating a clutch provided in a housing from outside the housing using a switching lever, the rotating portion being rotatably held on the housing and causing the switching lever to engage with the clutch; a grip portion that is provided on the outside of the housing contiguously with the rotating portion, the grip portion being formed in a radiating direction from a center of rotation of the rotating portion; and a lock button that is housed such that it is capable of protruding from and being depressed into a bottomed hole provided in the grip portion and such that it is urged in a direction of protrusion from the grip portion, the lock button engaging with a guide groove that is providcd in an outer surfacc of thc housing; characterized in that a communication hole is provided in the grip portion, the communication hole communicating between the bottomed hole and the outside of the grip portion and being capable of discharging dust that has entered into the grip portion.</claim-text> <claim-text>2. A hammer drill according to claim 1, wherein the communication hole is formed along the direction of protrusion and depression of the lock button.</claim-text> <claim-text>3. A hammer drill according to claim I or 2, wherein the communication hole is formed as a pair.</claim-text> <claim-text>4. A hammer drill according to any one of claims ito 3, wherein a plurality of engagement recesses are successively formed in the guide groove, and an engaging portion of the lock button engages with the engagement recesses in the direction of protrusion, at switching positions of the operation modes, the engaging portion and the engagement recesses having a tapered shape, in which they taper in the direction of protrusion.</claim-text> <claim-text>5. A hammer drill according to any one of claims Ito 4, wherein the communication hole is formed as a slit having an elongated rectangular shape in a cross section.</claim-text> <claim-text>6. A hammer drill according to claim 5, wherein the slit has a tapered shape, in which an opening is larger, in the width direction, on the side communicating with the bottomed hole than on the side communicating with the outside of the grip portion.</claim-text> <claim-text>7. A hammer drill according to any one of claims I to 6, wherein the lock button is urged in the direction of protrusion from the grip portion by a coil spring that is provided between the lock button and the bottom of the bottomed hole.</claim-text> <claim-text>8. A hammcr drill according to any one of claims I to 7, wherein the guide groove is formed in an arc shape centering around the rotating portion.</claim-text> <claim-text>9. A hammer drill according to any one of claims I to 8, wherein an engagement pin, which engages with the clutch, is provided on the rotating portion in a position that is eccentric to the center of rotation of the rotating portion, and a sliding operation of the clutch is possible due to eccentric movement of the engagement pin in line with rotation of the rotating portion.</claim-text> <claim-text>10. A hammer drill constructed and arranged to operate substantially as hereinbefore described with reference to the drawings.</claim-text>