Driving tool

A driving tool in a form of a combustion type nail driving machine 1 for injecting a nail by combustion gas is provided. The driving tool includes a lower pusher which is arranged at a distal end in a projecting direction of a nose through which the nail passes, formed with an elongated hole, and adapted to come into contact with a wood, an upper pusher which is urged by the lower pusher, and an extending-contracting mechanism interposed between the lower pusher and the upper pusher. The extending-contracting mechanism includes a bush which is in contact with the upper pusher and formed with a threaded hole, and a screwing part which can be screwed into the threaded hole after passing through the elongated hole. The screwing part includes a bolt which connects the lower pusher and the bush, and a lever.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims the benefit of priority from the prior Japanese Patent Application No. 2006-305535, filed on Nov. 10, 2006; the entire contents of which are incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a driving tool.

2. Description of Related Art

In a driving tool for driving a fastening piece such as a nail, driving of the nail or the like has been heretofore controlled by cooperation between a mechanism such as a trigger by which an operator inputs power and a mechanism for detecting that the driving tool is in contact with an object to be worked such as wood (a detecting mechanism).

In this detecting mechanism, a pusher is provided in an injection part in the driving tool from which the fastening piece is injected, as shown in JP-A-2000-334678. After it has been detected that this pusher has come into contact with the object to be worked, driving operation is conducted. By providing this pusher, too deep sinking or too short sinking of the fastening piece when it has been driven is avoided.

SUMMARY

In case where the pusher is always at a constant position with respect to the injection part, too deep sinking or too short sinking of the fastening piece may sometimes occur depending on types of wood. In order to avoid this phenomenon, mechanisms for changing the position of the pusher with respect to the injection part are disclosed as described in the related art.

In the mechanism disclosed in JP-A-2000-190251, an adjusting dial concerned with change of the position of the pusher is fixed by engagement between projected portions and recessed portions. However, they are not always reliably fixed, and so, it has sometimes happened that the adjusting dial is rotated, when it has accidentally struck some other member, and the position of the pusher is changed.

Besides, the mechanisms disclosed in JP-A-2000-334678, JP-A-2004-154870, and JP-A-2004-351523 are so complicated that the driving tools have become heavy in weight, and the number of maintenances has increased, resulting in high cost.

In view of the above, it is an object of the invention to provide a driving tool provided with a pusher whose position can be reliably fixed with a simple structure.

In order to solve the above described problem, there is provided according to the invention, a driving tool including: an injection part defining a passage for a fastening piece; a lower pusher being provided in the injection part so as to swing and to be brought into contact with an object to be worked; and an upper pusher adapted to slide in association with the lower pusher, wherein the driving tool further includes: a fixing part being in contact with the upper pusher and formed with a threaded hole; a threaded part being screwed into the threaded hole thereby to tightly connect the lower pusher to the fixing part; and a grasping part being provided between the threaded part and the fixing part, and capable of being grasped, wherein the threaded part has an engaging part adapted to be engaged with the grasping part, whereby the grasping part is movable between an engaged position in which it can be engaged with the engaging part and a non-engaged position in which it cannot be engaged with the engaging part. According to this structure, the structure of the driving tool can be simplified, and driving depth can be adjusted.

In the driving tool, it would be preferable that the lower pusher has an elongated hole which extends in the injecting direction, the lower pusher is fixed between the threaded part and the fixing part, when the threaded part is screwed into the threaded hole after passing through the elongated hole, and the lower pusher can move in the elongated hole, by rotating the grasping part while it is in the engaged position thereby to release the threaded part from screwed engagement. According to this structure, the structure of the driving tool can be simplified, and driving depth can be adjusted.

Moreover, it would be preferable that a spring for urging the grasping part with respect to the threaded part is interposed between the threaded part and the grasping part, and the grasping part moves to the engaged position against urging force of the spring.

According to this structure, the grasping part is prevented from moving to the engaged position, unless the grasping part is intentionally moved to the engaged position. As the results, it is possible to prevent the screwing part from rotating accidentally.

According to the invention, there is further provided a driving tool comprising a housing, a motive power part provided in the housing, a control part for controlling operation of the motive power part, an actuating part which is actuated by the motive power part to inject a fastening piece to an object to be worked, and an injection part which is provided at an end of the housing in an injecting direction in which the fastening piece is injected, and defines a passage for the fastening piece which is injected by the actuating part, characterized in that the control part includes a lower pusher which is arranged at a distal end of the injection part in the injecting direction, and adapted to come into contact with the object to be worked, an upper pusher which is urged by the lower pusher, and an extending-contracting mechanism which is interposed between the lower pusher and the upper pusher, the lower pusher is formed with an elongated hole extending in the injecting direction, the extending-contracting mechanism includes a bush formed with a threaded hole and adapted to be brought into contact with the upper pusher, and a screwing part which can be screwed into the threaded hole after passing through the elongated hole, the screwing part includes a threaded part which is screwed into the threaded hole thereby to tightly connect the lower pusher to the bush, and a grasping part which can be grasped, the threaded part has an engaging part which can be engaged with the grasping part, and the grasping part is so constructed as to be movable between an engaged position in which it can be engaged with the engaging part, and a non-engaged position in which it cannot be engaged with the engaging part.

According to this structure, the structure of the control part for controlling the motive power part can be simplified. Moreover, by rotating the screwing part, it becomes possible to restrict the position of the lower pusher, but the screwing part can be rotated only when the grasping part is in the engaged position. As the results, by usually arranging the grasping part in the non-engaged position, it is possible to make the screwing part non-rotatable, and hence, the screwing part can be prevented from rotating accidentally.

According to the invention, there is further provided a driving tool including: an injection part which defines a passage for a fastening piece, a lower pusher being slidably provided in the injection part and adapted to come into contact with an object to be worked, and an upper pusher which slides in association with the lower pusher, wherein the driving tool further includes: a fixing part which is arranged in contact with the upper pusher; a threaded part for tightly connecting the lower pusher to the fixing part; and a grasping part being provided between the threaded part and the fixing part and capable of being grasped, wherein the threaded part has an engaging part which can be engaged with the grasping part, and wherein the grasping part is movable between an engaged position in which it can be engaged with the engaging part and a non-engaged position in which it cannot be engaged with the engaging part. According to this structure, it is possible to easily adjust the position of the lower pusher, only by rotating the grasping part.

According to the driving tool of the invention, it is possible to provide the driving tool provided with the pusher whose position can be reliably fixed with the simple structure.

DESCRIPTION OF THE EMBODIMENTS

Referring toFIGS. 1 to 6, a driving tool in an embodiment according to the invention will be described. A combustion type nail driving machine1as shown inFIG. 1is a driving tool in which explosive power of combustible gas is used as motive power, and a nail is used as a fastening piece. The combustion type nail driving machine1includes a housing2as an outer shell, and a head cover3which is formed with a suction port (not shown) is attached to an upper part of the housing2. A handle4is extended from a side part of the housing2. The handle4is provided with a trigger switch5, and a battery4A is detachably inserted into the handle4. The trigger switch5cooperates with a head switch (not shown) which will be described below, so that the nail can be injected only when both of the switches are turned on.

A bomb chamber29is formed in the housing2at a position where the handle4is extended, and a gas bomb30containing combustible liquid gas is detachably contained in the bomb chamber29. A magazine6loaded with the nails (not shown) is provided in a lower part of the handle4.

A nose7coupled to a cylinder20, which will be described below, and forming an injection part to be opposed to a work28is extended from a lower end part of the housing2. The nose7guides sliding motion of a driver blade23A, which will be described below, and the nail (not shown) to be driven into the work28. A lower pusher9to be butted against the work28is held at an end7A of the nose7so as to protrude in a direction of injecting the nail (not shown).

The lower pusher9which includes a first pusher9A surrounding the end7A of the nose, and a second pusher9B extended from the end7A is arranged so as to reciprocally slide with respect to the end7A. Moreover, as shown inFIG. 3, the first pusher9A is formed with a hole9a, and the second pusher9B is formed with an elongated hole9bwhich extends in the injecting direction. The first pusher9A and the second pusher9B are arranged in such a manner that the hole9aand the elongated hole9bmay be overlapped, and the second pusher9B may come into contact with a bush10which will be described below.

As shown inFIG. 1, an upper pusher8which is fixed to a combustion chamber frame14, which will be described below, is disposed in a cylinder20which is located above the lower pusher9. A spring (not shown) is interposed between the upper pusher8and the cylinder20. Consequently, the upper pusher6is urged downward with respect to the cylinder20.

As shown inFIGS. 1 and 3, the bush10and a bolt11are interposed between the upper pusher8and the lower pusher9. As shown inFIG. 3, the bush10is bent in a substantially L-shape, and a contact part10A to be brought into contact with the upper pusher8is defined in a part which is bent and extended in a direction perpendicular to the injecting direction. Moreover, the bush10is formed with a threaded hole10ainto which the bolt11can be screwed, in a substantially center part thereof in the injecting direction.

As shown inFIG. 4, the bolt11has a threaded part11A, a contact part11B, an engaging part11C, and a flange part11D. The threaded part11A is arranged at a tip end of the bolt11and so constructed as to be screwed into the threaded hole10a.

The contact part11B is arranged adjacent to the threaded part11A, and so constructed that a substantially round shape is formed in a sectional plane perpendicular to a longitudinal direction of the bolt11. A diameter of the round shape in the contact part11B is larger than the hole9a(SeeFIG. 3). In case where the bolt11is screwed into the threaded hole10aafter passing through the hole9aand the elongated hole9b, the lower pusher9can be clamped between the contact part11B and the bush10by spirally forwarding the bolt11, whereby the lower pusher9can be integrally fixed to the bush10. Consequently, when the lower pusher9has come into contact with the wood28, the upper pusher8is urged by the bush10which is fixed to the lower pusher9, and can move upward.

The engaging part11C is arranged adjacent to the contact part11B, and so constructed that a substantially hexagonal shape is formed in a sectional plane perpendicular to the longitudinal direction of the bolt11. A diameter of the engaging part11C is larger than the diameter of the contact part11B. The flange part11D is positioned adjacent to the engaging part11C, at a backward end of the bolt11.

As shown inFIG. 3, a lever12and a spring13are interposed between the bolt11and the bush10. The lever12is provided with a grip12A which can be grasped, and formed with a hole12awhich has a substantially hexagonal shape and can be engaged with the engaging part11C. The bolt11is inserted into the elongated hole9b, after passing through the hole12a, to be screwed into the threaded hole10a. These bolt11and lever12constitute a screwing part, and this screwing part and the bush10constitute an extending-contracting mechanism.

The spring13is interposed between the flange part11D and the lever12. Therefore, the lever12is urged by the spring13in a direction toward the distal end of the bolt11, that is, toward the lower pusher9. Consequently, the contact part11B is positioned in the hole12a, and the engaging part11C will be never positioned in the hole12a, unless the lever12is lifted against urging force of the spring13. This position is defined as a non-engaged position of the lever12, while the position where the engaging part11C is engaged with the hole12ais defined as an engaged position. Because the contact part11B has a substantially round shape in section, the contact part11B will never rotate together with the lever12. Even though the lever12is rotated in a state as shown inFIG. 3, the bolt11is restrained from rotating together.

A head cap15for covering an opening at an upper end of the housing2is fixed to the upper end of the housing2. As shown inFIG. 1, a motor18carried by a buffer member17is positioned in the head cap15at the opposite side to a combustion chamber26, which will be described below, and an ignition plug (not shown) opposed to the combustion chamber26is provided near the motor18.

In addition, the head switch (not shown) for detecting that the below described combustion chamber frame14is positioned at an upper end of stroke is provided in the housing2. When the combustion type nail driving machine1has been pressed to the work28by the lower pusher9, and the upper pusher8has moved upward up to a determined position, this head switch is tuned on thereby to start rotation of the motor18.

A fuel passage25is formed in the head cap15at a side adjacent to the handle4. The fuel passage25opens to a lower end face of the head cap15at its one end, and a gas bomb connecting part25A to be connected to the gas bomb30is formed at the other end thereof.

The combustion chamber frame14which is movable in the longitudinal direction of the housing2, whereby an upper end of the combustion chamber frame14can be brought into contact with the lower end face of the head cap15is provided in the housing2. This combustion chamber frame14moves along with the movement of the upper pusher8, because the upper pusher8is coupled and fixed to the combustion chamber frame14. The cylinder20which is in contact with an inner peripheral face of the combustion chamber frame14to guide the movement of the combustion chamber frame14is fixed to the housing2. The cylinder20is formed with an exhaust hole21at a center part in an axial direction thereof. This exhaust hole21is provided with a check valve (not shown) so as to selectively close the exhaust hole.

As shown inFIG. 1, a piston23which is reciprocally movable with respect to the cylinder20is provided in the cylinder20. The piston23defines an upper chamber of the piston23and a lower chamber of the piston23inside the cylinder20. The driver blade23A is extended from a lower face of the piston23up to a position of the nose7, and a tip end of this driver blade23A becomes a position for striking the nail (not shown). Moreover, a bumper24formed of elastic material is arranged at a lower face of the cylinder20. Consequently, when the piston23has moved downward, the piston23strikes the bumper24at its lower dead center.

When the upper end of the combustion chamber frame14has come into contact with the head cap15, a combustion chamber26is defined by the head cap15, the combustion chamber frame14, and the upper chamber of the piston23. When the combustion chamber frame14is separated from the head chap15, a first flow passage communicated with an outside air is formed between the head cap15and the upper end of the combustion chamber frame14, and a second flow passage continued from the first flow passage is formed between the upper end of the combustion chamber frame14and the upper end of the cylinder20. Combustion gas and fresh air pass through these flow passages to flow around an outer peripheral face of the cylinder20, and the combustion gas and so on which have passed are exhausted from the exhaust port2aof the housing2. The above described suction port is formed for the purpose of supplying air into the combustion chamber26, and the combustion gas in the combustion chamber26is exhausted from the exhaust hole21.

Fans19are provided in the combustion chamber26. The fans19have three functions, as follows. When the combustion chamber frame14is in contact with the head cap15, the fans19rotate thereby to stir the air and the combustible gas to be mixed. After ignition, the fans19generate turbulent flow combustion thereby to accelerate the combustion. When the combustion chamber frame14is separated from the head cap15, and the first flow passage and the second flow passage are formed, the fans19exhaust the combustion gas in the combustion chamber26, and at the same time, cools down the cylinder20.

In the combustion type nail driving machine1, a distance from the lower pusher9to the nose7on occasion of driving the nail is changed depending on hardness and thickness of the wood28. In order to change a projecting amount of the lower pusher9from the nose7, the lever12is moved to the engaged position against the urging force of the spring13, as shown inFIG. 5, thereby allowing the engaging part11C to be engaged with the hole12a.

Because both the hole12aand the engaging part11C have a hexagonal shape, as shown inFIG. 6, the lever12and the bolt11can be rotated together. Therefore, the lever12is rotated by the grip12A, thereby to rotate the bolt11so as to spirally retreat. As the results, the lower pusher9is separated from the bush10, and the second pusher9B can slide with respect to the bush10and the first pusher9A in the injecting direction.

After the second pusher9B has slid with respect to the bush10and the first pusher9A in the injecting direction, and the lower pusher9has been positioned at the determined position, as shown inFIG. 7, the lever12is rotated to spirally advance the bolt11, whereby the first pusher9A and the second pusher9B is fixed to the bush10. Thereafter, by releasing a hand from the lever12, the lever12moves to the non-engaged position by the urging force of the spring13. In a state where the lever12is in the non-engaged position, the lever12and the bolt11will not be rotated together. Therefore, even though the lever12is rotated in this state, the bolt11will not be slackened, but can always keep the lower pusher9and bush10in a fixed state. Then, by arranging the grip12A along the injecting direction, as shown inFIG. 2, adjustment of the projecting amount of the lower pusher9from the nose7is completed.

The driving tool according to the invention is not limited to the above described embodiment, but various modifications and improvements can be made in a scope as described in the claims. For example, a scale9C may be formed on the first pusher9A at a position superposed on the second pusher9B, as shown inFIG. 8. In this manner, a moving amount of the second pusher9B with respect to the first pusher9A can be made clear, and it is possible to easily apprehend the projecting amount of the lower pusher9from the nose7.

Although the structure including the lever is employed in the grasping part, in the above described embodiment, the invention is not limited to this, but a structure including a member in a shape of a door knob may be employed. In this case too, it would be sufficient that the member can move between the non-engaged position and the engaged position with respect to the screwing part, and is kept in the non-engaged position in the ordinary state.

The invention can be applied to a driving tool for driving fastening pieces such as nails, staples and so on, by using gas, air, a motor etc. as motive power.