JP2015098068A - Driving tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent initial leakage to an exhaust passage when a head valve is opened, in an air-recycle type driving tool in which, after impact, compressed air supplied into a piston upper chamber is recycled into a piston lower chamber through a recycle passage, to thereby return the piston to the upper movement end.SOLUTION: A driving tool is constituted as follows. When a head valve 20 is opened, after a seal ring 25 abuts on a seal part 21c of a valve guide 21 to block an exhaust passage 24 to an accumulator 8, an adjustment seal part 22c is separated from the inner peripheral surface of the head valve 20, to thereby open the accumulator 8 to a piston upper chamber 11U, and to start supply of compressed air.

Description

  The present invention relates to a driving tool such as a nailing machine using compressed air as a driving source.

The compressed air drive type driving tool supplies a driving tool into a driving path one by one from a tool body in which a piston for driving is built, a handle portion gripped by a user, and a magazine loaded with a number of driving tools. A driving tool supply unit is provided. The driving path is provided in a nose portion provided in the tool body. A driving driver provided on the piston moves down in the driving passage, whereby one driving tool supplied from the driving tool supply unit is hit and driven out from the injection port.
The tool body includes a cylinder for airtightly accommodating the piston and a head valve for opening and closing the piston upper chamber of the cylinder. The head valve is opened and closed via a trigger valve that operates by operating a switch lever provided on the handle. By pulling the switch lever, the head valve is opened and compressed air flows from the accumulator into the piston upper chamber. When compressed air flows into the piston upper chamber, the piston is moved down and driven.
When the pull operation of the switch lever is released after the driving is completed, the head valve is closed and the flow of compressed air into the piston upper chamber is blocked, while the piston is lifted by the compressed air (return air) that flows into the piston lower chamber. Returned to dead point.
There are generally two methods for obtaining return air for returning the piston to the top dead center after hitting the driving tool. One is a system in which a part of the compressed air that has flowed into the piston upper chamber at the stage of lowering the piston flows into the return air chamber, and then flows into the piston lower chamber side to obtain return air. In this system, all the compressed air in the piston upper chamber is exhausted when the piston moves up (at the time of return). Hereinafter, this method is referred to as “normal exhaust method” for convenience.
The other is the stage where the head valve is closed by releasing the switch lever pull operation after the piston reaches the lower end, and then the piston upper chamber enters the return air chamber via the recycle passage branched from the exhaust passage. This is an air recycling method in which a part of the compressed air in the upper chamber of the piston is returned to the return air chamber by communicating, and flows into the lower chamber side of the piston to obtain return air. According to this air recycling method, a part of the compressed air in the piston upper chamber is reused as return air, and only the remaining compressed air is exhausted through the exhaust passage. Techniques relating to this air-recycling type driving tool are disclosed in the following patent documents.
According to the latter air recycling method, almost all of the compressed air that flows into the piston upper chamber when the piston moves down is efficiently consumed by the striking force of the piston. You can gain power. Also, according to the latter air recycling method, the compressed air that flows into the piston upper chamber and is consumed for generating impact force is not exhausted to the outside as in the former normal exhaust method, but is reused as return air. Therefore, it is possible to efficiently consume the compressed air and reduce the exhaust noise.

Japanese Patent No. 3344425

However, the latter air recycling type driving tool has the following problems. In the air recycling system, the head valve has a function for opening and closing the accumulator with respect to the piston upper chamber (accumulator opening and closing function) and a function for opening and closing the exhaust passage (and hence the recycling passage) with respect to the piston upper chamber (exhaust passage opening and closing function). ). The former accumulator opening / closing function is a function for supplying compressed air to the piston upper chamber, and the latter exhaust passage opening / closing function is to exhaust the compressed air in the piston upper chamber or return air (to return the piston to the upper moving end). This is a function necessary for reuse as compressed air supplied to the piston lower chamber.
As described above, in the air recycling method, the head valve needs to have both functions, and the vertical movement distance (opening / closing stroke) of the head valve is set larger than that in the normal exhaust method. As a result, in the conventional air recycling system, the accumulator is temporarily in communication with both the piston upper chamber and the exhaust passage when the head valve moves down, and a part of the compressed air supplied from the accumulator is There was a problem of exhausting wastefully through the exhaust passage.
In the present invention, in an air recycle driving tool that reuses part of the compressed air in the piston upper chamber, which is exhausted in the normal exhaust system, as return air, it is supplied from the accumulator to the piston upper chamber when the head valve is opened. The purpose is to eliminate the phenomenon of initial leakage in which a part of the compressed air leaked to the exhaust passage side, thereby reducing the exhaust noise and efficiently consuming the compressed air and obtaining a large striking force. And

Said subject is solved by each following invention.
A first invention is a piston that reciprocates using compressed air as a drive source, a head valve that opens and closes an accumulator with respect to the piston upper chamber, an exhaust passage that exhausts compressed air in the piston upper chamber, and compression of the piston upper chamber. This is an air recycling type driving tool provided with a recycling passage for returning air to the piston lower chamber. According to the first aspect of the present invention, in the process of opening the head valve, the timing adjustment seal portion (adjustment seal) that shuts off the supply of compressed air from the accumulator to the piston upper chamber until the exhaust passage is blocked from the accumulator. Part).
According to the first aspect of the invention, when the head valve is opened to start the driving operation, after the exhaust passage is blocked with respect to the accumulator, the adjustment seal portion is opened to compress the accumulator to the piston upper chamber. Air supply is started. Thereby, when the compressed air starts to be supplied from the accumulator to the piston upper chamber, it is possible to eliminate the phenomenon of initial leakage in which a part of the compressed air leaks to the exhaust passage side. By eliminating the initial leakage into the exhaust passage, all of the compressed air that has flowed from the accumulator can be supplied to the piston upper chamber and efficiently consumed as the piston's downward motion thrust (striking force).
As described above, at the time of starting the driving operation, the compressed air can be efficiently consumed to obtain a large striking force, and since the initial leakage is eliminated, the wasteful consumption of the compressed air is eliminated and the exhaust noise is reduced. be able to.
A second invention is the driving tool according to the first invention, wherein a top cap is provided on the upper portion of the tool body, and an adjustment seal portion is provided between the top cap and the head valve.
According to the second invention, the adjustment seal portion is provided between the top cap and the head valve. Since the adjustment seal portion is provided between the top cap and the head valve, the adjustment seal portion is opened and closed by moving the head valve relative to the top cap.
A third invention is the driving tool according to the second invention, wherein the top cap is provided with a valve seat having elasticity, and an adjustment seal portion is provided between the valve seat and the head valve.
According to the third invention, the adjustment seal portion is provided between the head valve and the valve seat. For this reason, the adjustment seal portion is opened and closed as the head valve moves relative to the valve seat.
In a fourth aspect based on the third aspect, the valve seat includes an inner peripheral side cylindrical portion located on the inner peripheral side of the head valve, and a gap between the outer peripheral surface of the inner peripheral side cylindrical portion and the head valve. This is a driving tool provided with an adjustment seal portion.
According to the fourth invention, the inner peripheral side cylindrical portion of the valve seat is located on the inner peripheral side of the annular head valve. An adjustment seal portion is provided between the outer peripheral surface of the inner peripheral cylindrical portion and the inner peripheral side of the head valve. By opening the adjustment seal portion, the compressed air on the accumulator side flows into the piston upper chamber through a gap (air supply passage) between the inner peripheral side of the head valve and the inner peripheral side cylindrical portion of the valve seat. A driving operation is performed.

5th invention is a driving tool provided with the adjustment seal part in the inner peripheral side cylindrical part of the valve seat in 4th invention.
According to the fifth aspect of the present invention, the accumulator is closed by contacting the inner peripheral surface of the head valve with the adjustment seal portion, while the accumulator is removed by removing the adjustment seal portion from the inner peripheral surface of the head valve. Is opened and compressed air is supplied to the piston upper chamber.
In a sixth aspect based on the third aspect, the valve seat includes an outer peripheral cylindrical portion located on the outer peripheral side of the head valve, and is adjusted between the inner peripheral surface of the outer peripheral cylindrical portion and the head valve. It is a driving tool provided with a seal part.
According to the sixth aspect, the outer peripheral side cylindrical portion of the valve seat is located on the outer peripheral side of the head valve. An adjustment seal portion is provided between the inner peripheral surface of the outer peripheral side cylindrical portion and the outer peripheral surface of the head valve. When this adjustment seal portion is opened, compressed air on the accumulator side flows into the piston upper chamber through an air supply passage between the outer peripheral side cylindrical portion of the valve seat and the head valve.
A seventh invention is a driving tool according to the sixth invention, wherein a seal ring is attached to the inner peripheral side of the head valve to form an adjustment seal portion.
According to the seventh aspect of the invention, the seal ring is brought into contact with the outer peripheral surface of the inner peripheral cylindrical portion of the valve seat, whereby the adjustment seal portion is closed and the air passage between the accumulator and the piston upper chamber is blocked. It will be in the state.
When the adjustment seal portion for blocking between the accumulator and the piston upper chamber is provided between the inner peripheral cylindrical portion of the valve seat and the head valve (fourth invention), the inner periphery of the valve seat The configuration in which the adjustment seal portion is provided in the side cylindrical portion corresponds to the fifth invention, and the configuration in which the seal ring is attached to the inner peripheral side of the head valve and the adjustment seal portion corresponds to the sixth invention. To do.
The eighth invention is a piston that reciprocates using compressed air as a drive source, a head valve that opens and closes an accumulator with respect to the piston upper chamber, an exhaust passage that exhausts compressed air in the piston upper chamber, and compression of the piston upper chamber. This is an air recycling type driving tool provided with a recycling passage for returning air to the piston lower chamber. In the eighth invention, the timing at which the head valve is opened is set after the exhaust passage is blocked from the accumulator.
According to the eighth invention, after the exhaust passage is blocked from the accumulator, the compressed air is supplied from the accumulator to the piston upper chamber to perform a driving operation. For this reason, a large striking force can be obtained and exhaust noise can be reduced by efficiently consuming compressed air by eliminating the phenomenon of initial leakage to the exhaust passage.

It is a longitudinal cross-sectional view of the whole driving tool which concerns on embodiment of this invention. It is a longitudinal cross-sectional view of a tool main body. This figure shows an initial state (non-operating state). It is an enlarged view of the (III) part in FIG. It is a longitudinal cross-sectional view of a tool main body. This figure shows a stage where the head valve starts to move downward by pulling the switch lever. It is an enlarged view of the (V) part in FIG. It is a longitudinal cross-sectional view of a tool main body. This figure shows a stage in the middle of the downward movement of the head valve. It is an enlarged view of the (VII) part in FIG. It is a longitudinal cross-sectional view of a tool main body. This figure shows a stage where the piston starts to move downward by supplying compressed air to the piston upper chamber by closing the exhaust passage and opening the head valve. It is an enlarged view of the (IX) part in FIG. It is a longitudinal cross-sectional view of a tool main body. This figure shows a stage in which the piston has reached the lower moving end and the driving operation has been completed by fully opening the head valve. It is an enlarged view of the (XI) part in FIG. It is a longitudinal cross-sectional view of a tool main body. This figure shows a stage where the pulling operation of the switch lever is released after the driving operation is completed, and the head valve starts to rise as a result. It is an enlarged view of the (XIII) part in FIG. This figure shows a state where the exhaust passage is blocked and the head valve is opened, and the piston still remains at the lower moving end. It is a longitudinal cross-sectional view of a tool main body. This figure shows a state in which the head valve is closed and the exhaust passage is opened, and the piston starts to rise from the lower moving end. It is an enlarged view of the (XV) part in FIG. It is a longitudinal cross-sectional view of a tool main body. This figure shows a state where the piston is returned to the upper moving end. This figure is different from FIGS. 2 and 3 showing the initial state in that it shows a state before the head valve reaches the upper moving end. It is an enlarged view of the (XVII) part in FIG. It is a longitudinal cross-sectional view which shows 2nd Embodiment of an adjustment seal | sticker part. It is a longitudinal cross-sectional view which shows 3rd Embodiment of an adjustment seal | sticker part. It is a longitudinal cross-sectional view which shows 4th Embodiment of an adjustment seal | sticker part.

Next, an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, a driving tool 1 according to the present embodiment is a so-called air-recycling nail driver using compressed air as a driving source, and a tool main body 10 and a driving nose extending downward from a lower portion of the tool main body 10. Part 2, a handle part 3 gripped by the user, a magazine 4 loaded with a number of driving tools (not shown), and driving tools one by one from the magazine 4 in conjunction with the driving operation. A driving tool feeding mechanism 5 for supplying the driving tool into the driving path is provided.
The tool body 10 includes a cylinder 12 in which a piston 11 is housed. An impact driver 13 is provided at the center of the lower surface of the piston 11. A head valve 20 for opening and closing the accumulator 8 with respect to the upper chamber of the piston 11 (piston upper chamber 11U) is provided on the upper outer periphery of the cylinder 12. The present invention is characterized by a compressed air supply / exhaust structure for the piston upper chamber 11U formed by opening and closing the head valve 20. The driving tool 1 of this embodiment does not exhaust the compressed air that has flowed into the piston upper chamber 11U as it is after the driving operation, but returns it to the lower chamber (piston lower chamber 11D) side of the piston 11 to move the piston 11 downward. It has a recycling system that returns from the end to the upper end. Details of the tool body 10 will be described later.
The handle portion 3 is provided so as to extend from the side of the tool body 10 to the side. A trigger valve 6 for switching between supply and exhaust of the tool main body 10 is accommodated on the lower surface on the base side of the handle portion 3. Below the trigger valve 6, a switch lever 7 is provided that is pulled (turned on) by the fingertip of the hand holding the handle portion 3 by the user. By pulling the switch lever 7, the trigger valve 6 is turned on. When the trigger valve 6 is turned on, the head valve lower chamber 20D is opened to the atmosphere through the air switching passage 9. When the head valve lower chamber 20D is opened to the atmosphere, the head valve 20 is opened and a driving operation is performed. When the pulling operation of the switch lever 7 is released, the trigger valve 6 is turned off. When the trigger valve 6 is turned off, compressed air is supplied through the air switching passage 9 into the head valve lower chamber 20D. The compressed air in the head valve lower chamber 20D acts in a direction to close the head valve 20. When the head valve 20 is closed, the piston upper chamber 11U is closed with respect to the accumulator 8, and the supply of compressed air to the piston upper chamber 11U is shut off.
A joint 3 a for connecting an air hose (not shown) for supplying compressed air is provided at the rear end of the handle portion 3. Compressed air is stored inside the handle portion 3 (accumulator 8) by an air hose connected through the joint 3a. The compressed air in the accumulator 8 always flows into the head valve upper chamber 20U. The compressed air in the head valve upper chamber 20U acts in the direction in which the head valve 20 is opened.
Between the rear end side of the handle part 3 and the driving nose part 2, a magazine 4 and a driving tool feeding mechanism 5 are provided in a suspended state. By operating the driving tool feeding mechanism 5 in conjunction with the driving operation of the tool body 10, driving tools are supplied one by one from the magazine 4 to the nose portion 2. The driving nose portion 2 is provided with a driving passage. The driver 13 moves down in the driving path by the driving operation of the tool body 10, whereby one driving tool is driven out from the injection port 2 a.

Details of the tool body 10 are shown in FIG. The tool body 10 includes a cylindrical body housing 14. The upper portion of the main body housing 14 is airtightly closed by the top cap 15, and the lower portion is airtightly closed by the front cap 16. An upper moving end damper 17 is attached to the lower surface of the top cap 15. A lower moving end damper 18 is attached to the upper surface of the front cap 16.
The cylinder 12 is accommodated on the inner peripheral side of the main body housing 14. When the piston 11 moves down in the cylinder 12, the driver 13 drives in and moves down in the driving passage of the nose portion 2, and the driving tool is hit.
A piston upper chamber 11U that is an upper portion of the cylinder 12 is opened and closed by a cylindrical head valve 20. The head valve 20 is disposed on the outer peripheral side of a valve guide 21 attached to the outer peripheral side of the cylinder 12. The head valve 20 is supported on the outer peripheral side of the valve guide 21 so as to be vertically displaceable. A compression spring 23 is interposed between the lower part of the head valve 20 and the lower part of the valve guide 21 in the head valve lower chamber 20D. By this compression spring 23, the head valve 20 is always urged in a direction in which it is displaced upward (in the closing direction). In a state in which compressed air is supplied into the head valve lower chamber 20D through the air switching passage 9 by turning off the trigger valve 6 (non-operating state), the head valve 20 is lifted by the air pressure and the urging force of the compression spring 23. And is held in the closed position of the upper moving end. In the closed state of the head valve 20, the piston upper chamber 11 </ b> U is airtightly blocked from the accumulator 8.
On the contrary, when the head valve lower chamber 20D is opened to the atmosphere through the air switching passage 9 by turning on the trigger valve 6, the head valve 20 is against the compression spring 23 by the compressed air in the head valve upper chamber 20U. Accordingly, the piston upper chamber 11U is opened with respect to the accumulator 8.

A cylindrical sheet holder 19 is attached to the lower surface of the top cap 15 and around the upper moving end damper 17. The upper part of the cylinder 12 enters the inner peripheral side of the sheet holder 19. A urethane rubber valve seat 22 is attached along the outer peripheral surface of the seat holder 19. The valve seat 22 also has a cylindrical shape, and includes a base portion 22a projecting in the radial direction and a cylindrical inner peripheral side cylindrical portion 22b extending axially downward from the inner peripheral side of the base portion 22a. . When the head valve 20 moves upward and its upper end is brought into contact with the lower surface of the base portion 22a of the valve seat 22, the upper moving end position of the head valve 20 is regulated and the piston upper chamber 11U is connected to the accumulator. 8 is in a state of being airtightly cut off from 8 (a state in which the accumulator 8 is closed).
As shown in FIG. 3, in order to adjust the timing at which an exhaust passage 24 (to be described later) is closed and the timing at which the accumulator 8 is opened with respect to the piston upper chamber 11U on the outer peripheral surface of the inner cylindrical portion 22b of the valve seat 22. The adjustment seal portion 22c is integrally provided. As shown in the drawing, the adjustment seal portion 22c is formed so as to protrude in the radial direction along the outer peripheral surface of the lower end portion of the inner peripheral cylindrical portion 22b. The piston upper chamber 11U is also hermetically sealed from the accumulator 8 by contacting the adjustment seal portion 22c with the inner peripheral surface of the head valve 20. The position of the adjustment seal portion 22c in the vertical direction is that the adjustment seal portion 22c is separated from the inner peripheral surface of the head valve 20 after the exhaust passage 24 is hermetically closed by the seal ring 25 in the process of opening the head valve 20. The accumulator 8 is set at a position where the accumulator 8 is relatively disengaged and opened with respect to the piston upper chamber 11U.

An exhaust passage 24 is provided between the head valve 20 and the valve guide 21. The exhaust passage 24 is branched into a recycle passage 28 through vent holes 21 a to 21 a provided in the valve guide 21. The recycle passage 28 is provided between the cylinder 12 and the valve guide 21. After striking the driving tool, in the upward movement process of the piston 11, the compressed air in the piston upper chamber 11U is recirculated into the piston lower chamber 11D through the recycling passage 28. The piston 11 is returned to the upper moving end by the compressed air recirculated into the piston lower chamber 11D through the exhaust passage 24 and the recycle passage 28.
The exhaust passage 24 is airtightly blocked from the piston upper chamber 11U by a seal ring 25 attached to the upper inner peripheral surface of the head valve 20. As shown in FIGS. 2 and 3, the seal ring 25 is separated from the seal portion 21 c of the valve guide 21 in a state where the head valve 20 is located at the closed position in which the upper end portion is in contact with the base portion 22 a of the valve seat 22. doing. In this state, the exhaust passage 24 and the recycle passage 28 are open to the piston upper chamber 11U (exhaust passage open state). On the contrary, as shown in FIGS. 8 to 13, when the head valve 20 moves downward from the closed position and the seal ring 25 comes into contact with the seal portion 21 c of the valve guide 21, the exhaust passage 24 and the recycle passage 28 become pistons. It will be in the state closed airtight with respect to the upper chamber 11U (exhaust passage interruption | blocking state).
In the former exhaust passage open state, the adjustment seal portion 22 c of the valve seat 22 is in contact with the inner peripheral surface of the head valve 20 and the exhaust passage 24 is airtightly blocked from the accumulator 8. As the head valve 20 moves downward, the seal ring 25 integrally moves downward, and then the seal ring 25 comes into contact with the seal portion 21c of the valve guide 22 so that the exhaust passage 24 and the recycle passage 28 are airtight from the piston upper chamber 11D. Blocked. In the downward movement process of the head valve 20, the adjustment seal portion 22 c of the valve seat 22 is in contact with the inner peripheral surface of the head valve 20 until the seal ring 25 contacts the seal portion 22 c of the valve guide 22. Thus, the relative positions of the seal ring 25 and the adjustment seal portion 22c are set appropriately.

After the exhaust passage 24 is hermetically blocked by the seal ring 25, the adjustment seal portion 22 c of the valve seat 22 is detached from the inner peripheral surface of the head valve 20 in the process in which the head valve 20 further moves downward. When the adjustment seal portion 22c is relatively disengaged from the inner peripheral surface of the head valve 20, the piston upper chamber 11U is opened to the accumulator 8, so that compressed air is supplied to the piston upper chamber 11U. When the accumulator 8 is opened, the exhaust passage is cut off as described above, so that the initial leak in which the compressed air flowing from the accumulator 8 flows into the exhaust passage 24 and the recycle passage 28 does not occur.
Therefore, the timing at which the head valve is opened when the adjustment seal portion 22c is relatively disengaged from the inner peripheral surface of the head valve 20 is such that the seal ring 25 contacts the seal portion 22c of the valve guide 22 and the exhaust passage. 24 is set after being shut off.
The exhaust passage 24 reaches an exhaust chamber 26 provided around the valve guide 21. The exhaust chamber 26 communicates with the exhaust passage 27 through an exhaust hole 20 a provided on the lower side of the head valve 20.
The downstream side of the recycle passage 28 communicates with the return air chamber 30 via a check valve 21 b provided at the lower part of the valve guide 21. The check valve 21b prevents the compressed air that has once returned to the return air chamber 30 from flowing back to the recycle passage 28 side. The return air chamber 30 is airtightly defined between the lower portion of the cylinder 12 and the main body housing 14. The return air chamber 30 communicates with the cylinder lower chamber 11D through an air passage 31 provided in the lower portion of the cylinder 12.

Hereinafter, a series of driving operations of the driving tool 1 will be described in order. 2 and 3 show an initial state (non-operating state) of the driving tool 1. In this initial state, as a result of the compressed air being supplied to the head valve lower chamber 20D through the air switching passage 9, the head valve 20 is closed. For this reason, the piston upper chamber 11U is cut off from the accumulator 8. Further, in this initial state, the head valve 20 is positioned and closed at the upper moving end, so that the seal ring 25 is spaced upward from the seal portion 21 c of the valve guide 21. Therefore, the exhaust passage 24 and the recycle passage 28 are open to the piston upper chamber 11U.
As shown in FIG. 4, when the trigger valve 6 is turned on by pulling the switch lever 7, the head valve lower chamber 20 </ b> D is exhausted through the air switching passage 9. Therefore, as shown in FIGS. 4 and 5, the head valve 20 starts to move down against the compression spring 23 by the air pressure in the head valve upper chamber 20U. At this stage, since the adjustment seal portion 22c of the valve seat 22 is in contact with the inner peripheral surface of the head valve 20, the piston upper chamber 11U is still cut off from the accumulator 8. Further, although the head valve 20 starts to move downward, the seal ring 25 is still separated from the seal portion 21c of the valve guide 21 as shown in the figure. For this reason, the exhaust passage 24 and the recycle passage 28 are open with respect to the piston upper chamber 11U.
As shown in FIGS. 6 and 7, when the head valve 20 further moves down, the flow area between the exhaust passage 24 and the exhaust chamber 26 is reduced by the exhaust throttle portion 20 c provided on the inner peripheral surface of the head valve 11. Is almost interrupted. Also at this stage, since the adjustment seal portion 22c of the valve seat 22 is in contact with the inner peripheral surface of the head valve 20, the piston upper chamber 11U is still airtightly blocked from the accumulator 8.

As shown in FIGS. 8 and 9, when the head valve 20 further moves down, the seal ring 25 comes into contact with the seal portion 21c of the valve guide 21, and the exhaust passage 24 is airtightly blocked from the piston upper chamber 11U. It becomes. Thereafter, the adjustment seal portion 22c of the valve seat 22 is relatively separated from the inner peripheral surface of the head valve 20, so that the piston upper chamber 11U is opened to the accumulator 8. When the piston upper chamber 11U is opened with respect to the accumulator 8, compressed air is supplied to the piston upper chamber 11U, whereby the piston 11 starts to move downward.
Thus, as the head valve 20 moves downward, the seal ring 25 comes into contact with the seal portion 21c of the valve guide 21, and the exhaust passage 24 is thereby airtightly blocked from the piston upper chamber 11U. Later, the adjustment seal portion 22c is relatively separated from the inner peripheral surface of the head valve 20, whereby the accumulator 8 is opened and compressed air is supplied to the piston upper chamber 11U. Therefore, a part of the compressed air that has flowed from the accumulator 8 into the piston upper chamber 11U does not flow into the exhaust passage 24 and the recycle passage 28, and so-called initial leakage can be eliminated.
As shown in FIGS. 10 and 11, when the head valve 20 reaches the lower end and the accumulator 8 is fully opened, the piston 11 reaches the lower end and the driving operation is completed. Until the piston 11 reaches the lower end, the seal ring 25 is maintained in contact with the seal portion 21c of the valve guide 21, and the exhaust passage 24 and the recycle passage 28 are airtight from the piston upper chamber 11U and the accumulator 8. It is kept in a blocked state. While the piston 11 extends from the upper moving end to the lower moving end, the piston lower chamber 11D, the return air chamber 30, the recycle passage 28, and the exhaust chamber 26 are maintained in an exhaust state (atmospheric release state).

After the piston 11 reaches the lower moving end and the driving operation of one driving tool is performed, the pulling operation of the switch lever 7 is released and the trigger valve 6 is turned off, and then the head valve lower chamber 20D passes through the air switching passage 9. Compressed air is supplied. By supplying compressed air to the head valve lower chamber 20D, the head valve 20 is moved up and closed. 12 and 13 show a state in which the trigger valve 6 is turned off and the head valve 20 starts to move upward. At this stage, the exhaust passage 24 and the recycling passage 28 are closed with respect to the piston upper chamber 11U and the accumulator 8. For this reason, the return air for moving the piston 11 positioned at the lower moving end upward is not supplied to the piston lower chamber 11D. Therefore, as shown in the drawing, the piston 11 is still positioned at the lower moving end.
In the process in which the head valve 20 further moves upward, the adjustment seal portion 22c of the valve seat 22 is brought into contact with the inner peripheral surface of the upper end, and the accumulator 8 is closed. At this stage, the supply of compressed air to the piston upper chamber 11U is shut off, while the exhaust passage 24 and the recycle passage 28 are kept shut off.
After the accumulator 8 is closed in this way, the head valve 20 further moves upward, so that the seal ring 25 is removed from the seal portion 21c of the valve guide 21 and the exhaust passage 24 is opened as shown in FIGS. In this way, when the head valve 20 is closed, the exhaust passage 24 is opened after the accumulator 8 is closed, thereby preventing so-called after-leakage.
14 and 15, the seal ring 25 is removed from the seal portion 21c and the exhaust passage 24 is opened, while the exhaust chamber 26 is throttled by the exhaust throttle portion 20c. Therefore, the compressed air in the piston upper chamber 11U is compressed. Preferentially flows from the exhaust passage 24 through the vent holes 21a to 21a to the recycle passage 28 side. The compressed air that has flowed into the recycle passage 28 flows into the return air chamber 30, and further supplied to the piston lower chamber 11D through the air passage 31, whereby the piston 11 starts to move upward as shown in FIG.

While the piston 11 moves upward, the compressed air in the piston upper chamber 11U is returned to the return air chamber 30 via the recycle passage 24, whereby the return air is continuously supplied to the piston lower chamber 11D. As described above, the piston 11 that has reached the lower moving end is returned to the upper moving end by recycling (reusing) the compressed air in the piston upper chamber 11U through the exhaust passage 24 and the recycle passage 28.
As shown in FIGS. 16 and 17, the exhaust chamber 26 is throttled by the exhaust throttle portion 20 c of the head valve 20 before the head valve 20 reaches the upper moving end. For this reason, the compressed air that has flowed into the exhaust passage 24 from the piston upper chamber 11U preferentially flows into the return air chamber 30 via the recycle passage 28 and is efficiently reused as return air.
After the piston 11 is returned to the upper end, the head valve 20 returns to the initial state shown in FIGS. 2 and 3 when the head valve 20 is returned to the upper end. At the stage where the head valve 20 is returned to the upper moving end, the interval between the exhaust throttle portion 20c of the head valve 20 and the valve guide 21 is increased, and the exhaust throttle portion 20c is opened. When the exhaust throttle portion 20c is opened, the compressed air in the piston upper chamber 11U and the exhaust passage 24 is exhausted to the atmosphere through the exhaust chamber 26, the exhaust holes 20a to 20a, and the exhaust passage 27.
Further, even if the remaining compressed air that flows into the piston lower chamber 11D through the return air chamber 30 is connected, an exhaust hole provided on the lower side of the piston 11 at the upper part of the cylinder 12 and returned to the upper moving end. The gas is exhausted to the piston upper chamber 11U side through 12a, and finally exhausted to the atmosphere through the exhaust passage 27. Thus, a series of driving operations by one pulling operation of the switch lever 7 is completed.

According to the driving tool 1 of the present embodiment configured as described above, when the head valve 20 is opened by the pulling operation of the switch lever 7, the seal ring 25 comes into contact with the seal portion 21c of the valve guide 21 and the exhaust passage. Since the adjustment seal portion 22c is relatively disengaged from the inner peripheral surface of the head valve 20 and the accumulator 8 is opened after the block 24 is shut off, a part of the compressed air flowing from the accumulator 8 into the piston upper chamber 11U. The conventional initial leakage phenomenon that flows into the exhaust passage 24 can be eliminated.
Since the phenomenon of initial leakage when the head valve 20 is opened can be eliminated, all of the compressed air flowing in from the accumulator 8 is efficiently consumed as the downward thrust (striking force) of the piston 11, thereby obtaining a large striking force. Can do.
Further, exhaust noise can be reduced by eliminating the initial leakage to the conventional exhaust passage side.
Further, when the head valve 20 is moved downward and opened, the accumulator 8 is opened after the exhaust passage 24 is closed to prevent initial leakage, so the head valve 20 is moved upward. In the closed stage, the exhaust passage 24 is opened after the accumulator 8 is closed, thereby preventing so-called after-leakage.
Therefore, the exhaust passage 24 in the present embodiment is configured to be opened only in a state where the accumulator 8 is always closed during a series of driving operations, thereby eliminating both initial leakage and rear leakage.

Various modifications can be made to the embodiment described above. For example, although the configuration in which the adjustment seal portion 22c is provided on the inner peripheral cylindrical portion 22b of the valve seat 22 is illustrated, the adjustment seal portion can be provided in various forms. For example, as shown in FIG. 18, a seal ring can be attached to the inner peripheral side of the head valve 20 to form the adjustment seal portion 32. Also with the adjustment seal portion 32 according to the second embodiment, when the head valve 20 is opened, the adjustment seal portion 32 is detached from the inner circumferential side cylindrical portion 22b of the valve seat 22 after the exhaust passage 24 is closed. By opening the accumulator 8, initial leakage and after-leakage are prevented.
Further, for example, as shown in FIG. 19, instead of the exemplified valve seat 22, a valve seat 35 having an outer peripheral cylindrical portion 35 a is attached to the outer peripheral side of the seat holder 19, while an adjustment seal portion is provided on the outer peripheral surface of the head valve 20. It is good also as a structure which attached the seal ring as 33. FIG. In the case of the third embodiment, the outer peripheral side cylindrical portion 35a of the valve seat 35 is located on the outer peripheral side of the head valve 20, and the adjustment seal portion 33 is brought into contact with the inner peripheral surface of the outer peripheral side cylindrical portion 35a. As a result, the accumulator 8 is closed with respect to the piston upper chamber 11U. When the head valve 20 is moved downward and the adjustment seal portion 33 is removed from the inner peripheral surface of the outer cylindrical portion 35a, the accumulator 8 is opened and compressed air flows into the piston upper chamber 11U.
When the head valve 20 is opened, the timing at which the adjustment seal portion 33 is removed from the inner peripheral surface of the outer cylindrical portion 35a is set after the exhaust passage 24 is hermetically closed by the seal ring 25. For this reason, the initial leakage and the rear leakage can be prevented also by the adjustment seal portion 33 according to the third embodiment.
Furthermore, as shown in FIG. 20, a sealing convex portion may be integrally provided on the lower inner peripheral surface of the outer peripheral cylindrical portion 35 a to form the adjustment seal portion 34. Also in the fourth embodiment, the accumulator 8 is opened with respect to the piston upper chamber 11U by the adjustment seal portion 34 being relatively disengaged from the outer peripheral surface of the head valve 20 when the head valve 20 is opened. Since the timing at which the adjustment seal portion 34 is opened is also set after the exhaust passage 24 is shut off, the initial leak and the rear leak are prevented, and the compressed air is efficiently supplied to the piston upper chamber 11U, resulting in a large impact force. In addition to being able to obtain, exhaust air noise can be reduced by eliminating unnecessary air consumption.

In the first to fourth embodiments described above, the configuration in which the adjustment seal portion is provided between the valve seat 22 attached to the top cap 15 and the head valve 20 is illustrated, but the inner peripheral side cylindrical portion 22b is omitted. The adjustment seal portion is provided between the head valve 20 and the seat holder 19 or the cylindrical portion is integrally provided on the lower surface of the top cap 15, and the adjustment seal portion is provided between the cylinder portion and the head valve. Also good.
Further, although not shown, an adjustment seal portion may be provided between the head valve 20 and the cylinder 12. After the exhaust passage 24 (and hence the exhaust chamber 26 and the exhaust passage 27) is closed with respect to the accumulator 8 between the inner peripheral surface of the head valve 20 and the outer peripheral surface of the cylinder 12, the piston upper chamber 11U is connected to the accumulator. By providing the adjustment seal portion that opens, the phenomenon of initial leakage and rear leakage to the exhaust side can be eliminated.
In such a configuration, the upper end portion of the head valve 20 can have a function as an opening / closing valve of the accumulator 8 for the piston upper chamber 11U.
As described above, the compressed air supplied from the accumulator 8 to the piston upper chamber 11U is returned to the piston lower chamber 11D through the exhaust passage 24 and the recycle passage 28 after the piston is moved downward, thereby moving the piston 11 to the upper end. In the air-recycling type driving tool configured to return, the timing of opening the head valve 20 is set after the exhaust passage 24 is blocked from the accumulator 8, thereby reducing the phenomenon of initial leakage and rear leakage of compressed air. As a result, it is possible to efficiently consume compressed air and obtain a large striking force, and to reduce exhaust noise.
The present invention is not limited to a driving tool in which the recycling passage 28 is branched from the exhaust passage 24 via the vent holes 21a to 21a as illustrated, but driving in a form in which the exhaust passage and the recycling passage are independently provided. The same applies to tools. In this case, similar effects can be obtained by adopting a configuration in which the accumulator is opened with respect to the piston upper chamber after both the exhaust passage and the recycle passage are closed along with the downward movement of the head valve.

DESCRIPTION OF SYMBOLS 1 ... Driving tool 2 ... Driving nose part 3 ... Handle part, 3a ... Joint 4 ... Magazine 5 ... Driving tool feeding mechanism 6 ... Trigger valve 7 ... Switch lever 8 ... Accumulator (accumulation chamber)
9 ... Air switching passage 10 ... Tool body 11 ... Piston 11U ... Piston upper chamber, 11D ... Piston lower chamber 12 ... Cylinder, 12a ... Exhaust hole 13 ... Driver 14 ... Main body housing 15 ... Top cap 16 ... Front cap 17 ... Up End damper 18 ... Lower moving end damper 19 ... Seat holder 20 ... Head valve 20a ... Exhaust hole, 20c ... Exhaust throttle 20U ... Head valve upper chamber, 20D ... Head valve lower chamber 21 ... Valve guide 21a ... Vent hole, 21b ... Check valve, 21c ... Seal portion 22 ... Valve seat 22a ... Base portion, 22b ... Inner peripheral cylindrical portion, 22c ... Adjustment seal portion 23 ... Compression spring 24 ... Exhaust passage 25 ... Seal ring 26 ... Exhaust chamber 27 ... Exhaust passage 28 ... Recycling passage 30 ... Return air chamber 31 ... Air passage 32 ... Adjustment seal portion (second embodiment)
33 ... Adjustment seal portion (third embodiment)
34 ... Adjustment seal portion (fourth embodiment)

Claims (8)

A piston that reciprocates using compressed air as a drive source, a head valve that opens and closes an accumulator with respect to the upper chamber of the piston, an exhaust passage that exhausts compressed air in the upper chamber of the piston, and a compressed air in the upper chamber of the piston below the piston A driving tool with a recycling passage that returns to the chamber,
A driving tool including an adjustment seal portion that shuts off supply of compressed air from the accumulator to the piston upper chamber until the exhaust passage is shut off from the accumulator during the opening process of the head valve. 2. The driving tool according to claim 1, wherein a top cap is provided on an upper portion of the tool body, and the adjustment seal portion is provided between the top cap and the head valve. The driving tool according to claim 2, wherein a valve seat having elasticity is provided on the top cap, and the adjustment seal portion is provided between the valve seat and the head valve. The driving tool according to claim 3, wherein the valve seat includes an inner peripheral side cylindrical portion located on an inner peripheral side of the head valve, and an outer peripheral surface of the inner peripheral side cylindrical portion, the head valve, A driving tool provided with the adjustment seal portion in between. The driving tool according to claim 4, wherein the adjustment seal portion is provided on an inner peripheral side cylindrical portion of the valve seat. The driving tool according to claim 3, wherein the valve seat includes an outer peripheral side cylindrical portion positioned on an outer peripheral side of the head valve, and the inner peripheral surface of the outer peripheral side cylindrical portion is interposed between the head valve and the head valve. A driving tool provided with the adjustment seal portion. The driving tool according to claim 6, wherein a seal ring is attached to an outer peripheral side of the head valve to form the adjustment seal portion. A piston that reciprocates using compressed air as a drive source, a head valve that opens and closes an accumulator with respect to the upper chamber of the piston, an exhaust passage that exhausts compressed air in the upper chamber of the piston, and a compressed air in the upper chamber of the piston below the piston A driving tool having a recycle passage for returning to the chamber, wherein the timing for opening the head valve is set after the exhaust passage is blocked from the accumulator.

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