Air compression tool

Abstract

Provided is an air pressure tool in which an O-ring is less likely to come off a valve stem of a relief valve. A driving tool as an air pressure tool has a chamber (33) that stores compressed air, and a relief valve (2) provided to the chamber. The relief valve has an inflow flow path (7a) that communicates with the chamber, and a discharge flow path (7b) formed on a downstream side of the inflow flow path (7a) and having a larger diameter than the inflow flow path. A valve stem (3) moves along the inflow flow path. An O-ring (6) that seals the inflow flow path is fitted to an annular groove on an outer periphery of the valve stem. A bleed groove is formed in the valve stem. The bleed groove has an inlet portion that opens to an inner peripheral chamber and a discharge outlet that opens to the discharge flow path, to discharge compressed air from the inner peripheral chamber to the discharge flow path when the O-ring, due to the internal pressure of the chamber, goes beyond the inflow flow path and further compresses air in the inner peripheral chamber between a wall surface of the annular groove and an inner peripheral surface of the O-ring toward the middle of the discharge flow path.

Description

Technical Field

[0001] This invention relates to compressed air tools. Background Technology

[0002] Compressed air tools utilize compressed air for their operations. For example, compressed air is supplied to the tool from an air supply source (air compressor). A typical compressed air tool is a drive tool, which uses compressed air as power to drive fasteners such as nails, threaded parts, and staples into a workpiece. A drive tool has: a chamber for storing compressed air; a piston that moves up and down due to the compressed air; and a pneumatic motor that obtains torque from the compressed air. While the pneumatic motor rotates the screwdriver head, the piston lowers the screwdriver head. Thus, the screwdriver head drives the threaded part into the workpiece.

[0003] Conventionally, such pneumatic tools have included an overflow valve (see, for example, Patent Document 1) in their chambers that opens the chamber to the atmosphere when the internal pressure becomes abnormal. The overflow valve, for example, has an O-ring mounted on the valve stem, which seals the flow path between the chamber and the external air.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-237374

[0005] A relief valve typically returns to its original state once the chamber is opened to the atmosphere and the internal pressure returns to normal. However, under extremely high internal pressure, the O-ring may detach from the valve stem during operation. Therefore, to reuse the relief valve, the O-ring needs to be re-embedded into the valve stem. This requires resuming the relief valve's operation. Consequently, relief valves that prevent the O-ring from easily detaching from the valve stem were previously preferred. Summary of the Invention

[0006] According to one feature of this disclosure, the air compressor tool includes: a chamber for storing compressed air; and an overflow valve disposed within the chamber. The overflow valve has: an inflow passage communicating with the chamber; and a discharge passage formed downstream of the inflow passage, and having a larger diameter than the inflow passage. A valve stem moves along the inflow passage. An O-ring sealing the inflow passage is fitted in an annular groove on the outer periphery of the valve stem. A venting path is formed in the valve stem. The venting path has an inlet at an opening in the inner peripheral chamber and an outlet at an opening in the discharge passage, for discharging compressed air from the inner peripheral chamber to the discharge passage when compressed air enters the inner peripheral chamber between the wall of the annular groove and the inner peripheral surface of the O-ring midway through the inflow passage towards the discharge passage due to the internal pressure of the chamber.

[0007] Therefore, as the O-ring expands towards the discharge path, the compressed air entering the inner circumferential chamber promotes further expansion. However, simultaneously, the compressed air is discharged from the inner circumferential chamber to the discharge path via the venting path. This prevents the O-ring from expanding and dislodging from the valve stem. As a result, the need for re-inserting the O-ring into the valve stem for reuse of the relief valve is eliminated. Attached Figure Description

[0008] Figure 1 This is a cross-sectional view of the injection tool.

[0009] Figure 2 yes Figure 1 The view of the section along line II-II.

[0010] Figure 3 It is a 3D view of the valve stem.

[0011] Figure 4 yes Figure 2 A view of the section along line IV-IV.

[0012] Figure 5 This diagram shows the state where the relief valve is working and the O-ring seal is released.

[0013] Figure 6 This is a diagram illustrating the function of the venting groove.

[0014] Figure 7 This is a partial cross-sectional view of the relief valve involved in other embodiments.

[0015] Figure 8 This diagram illustrates the expansion of the O-ring in an overflow valve without a vent groove.

[0016] Figure 9 It means in Figure 8 A diagram showing the state of the O-ring detached from the valve stem in the relief valve.

[0017] Explanation of reference numerals in the attached figures

[0018] 1...Injection tool; 2...Overflow valve; 3...Valve stem; 3a...Sliding part; 3b...Head; 3c...Sliding body part; 3d...Stop part; 3e...Leg part; 3i...Slit; 4...Annular groove; 4a...Upstream side wall; 4b...Downstream side wall; 4c...Bottom surface; 4d...Inner peripheral chamber; 5a~5d...Vent groove (5); 5e, 75e...Inlet part; 5f, 75f...Outlet; 6...O-ring; 6a...Inner peripheral surface; 6b...Outer peripheral surface; 7...Valve box; 7a...Inflow path; 7b...Outflow path; 7c...Base; 7d...Conical surface; 7e...Abutment surface; 7f...Inner peripheral surface of cylinder; 7 g... Pin hole; 20... Tool body; 21... Body housing; 22... Cylinder; 23... Piston; 24... Screwdriver head; 25... Downward moving end damper; 26... Head rotating part; 27... Nose; 27a... Drive-in passage; 27b... Contact arm; 28... Gear train; 30... Handle; 31... Trigger; 32... Start valve; 33... Chamber; 40... Screw cartridge; 40a... Screw feed mechanism; 45... Pneumatic motor; 50... Cover; 51... Pressure regulating valve; 52... Connector; 70... Valve stem; 75... Vent hole; 90... Overflow valve; B... Screw; H... Air hose; W... Fastener. Detailed Implementation

[0019] According to other features of this disclosure, the venting path is formed by a groove in the wall of the annular groove, which is formed on the downstream side wall supporting the O-ring from the downstream side of the compressed air. The groove extends radially in the valve stem. Therefore, compared with, for example, a construction in which a through hole is formed in the valve stem and the inner peripheral chamber is connected to the discharge flow path through the through hole, the venting path can be obtained simply.

[0020] According to other features of this disclosure, multiple grooves are formed on the downstream sidewall of the annular groove. Therefore, compared to the case where only one groove is formed, the compressed air entering the inner peripheral chamber is rapidly discharged to the discharge path. Thus, the expansion of the O-ring can be more effectively suppressed.

[0021] According to other features of this disclosure, the pneumatic tool has a handle that is held by the user and houses a chamber. An overflow valve is provided on the end face of the handle. Therefore, the direction of compressed air discharged from the overflow valve is axial towards the handle. Therefore, even when compressed air is discharged from the overflow valve, the chance of compressed air coming into contact with the operator is reduced.

[0022] According to other features of this disclosure, the pneumatic tool has a pressure regulating valve that reduces the pressure of external compressed air and supplies it to the chamber. The pneumatic tool has a drive tool body equipped with a screwdriver for driving fasteners into place using compressed air from the chamber. Therefore, the external compressed air is reduced to an appropriate pressure for operating the screwdriver via the pressure regulating valve.

[0023] According to other features of this disclosure, the pneumatic tool includes: a chamber for storing compressed air; and an overflow valve disposed within the chamber. The overflow valve has: an inflow passage communicating with the chamber; and a discharge passage formed downstream of the inflow passage, and having a larger diameter than the inflow passage. A valve stem moves along the inflow passage. An O-ring sealing the inflow passage is fitted into an annular groove on the outer periphery of the valve stem. An O-ring detachment suppression structure is provided, which limits the possibility that the O-ring may radially expand and detach from the valve stem midway as it crosses the inflow passage and approaches the discharge passage due to the internal pressure of the chamber.

[0024] Therefore, the O-ring detachment-inhibiting structure prevents the O-ring from expanding radially or detaching from the valve stem. This eliminates the need for the restoration work of re-embedding the O-ring into the valve stem for reuse of the relief valve.

[0025] like Figure 1 As shown, the drive tool 1 is, for example, a handheld screw (threaded part) fastening tool known as a so-called screw drive machine. The drive tool 1 includes: a tool body 20 with an impact mechanism; a handle 30 for the user to hold; a screw magazine 40 capable of holding multiple screws B; and a pneumatic motor 45.

[0026] like Figure 1 As shown, the tool body 20 has a cylindrical body housing 21. An impact mechanism comprising a cylinder 22 and a piston 23 is housed within the body housing 21. A long, rod-shaped screwdriver head 24 is attached to the lower surface of the piston 23. The screwdriver head 24 extends downwards. The screwdriver head 24 protrudes from the cylinder 22 via the inner circumferential side of a downwardly moving end damper 25 located at the lower part of the cylinder 22.

[0027] like Figure 1 As shown, a drive nose 27 is provided at the lower part of the tool body 20. The drive nose 27 extends downward for a considerable distance. The screwdriver head 24 enters the interior of the drive nose 27 (drive passage 27a).

[0028] like Figure 1 As shown, the handle portion 30 extends laterally from the side of the tool body 20. A chamber 33 containing compressed air is provided inside the handle portion 30. An actuation valve 32 is provided on the lower surface of the base of the handle portion 30. A trigger 31 is provided below the actuation valve 32 and on the side of the tool body 20.

[0029] like Figure 1 As shown, the trigger 31 is pulled upwards by the fingertips of the hand holding the handle 30. Pulling the trigger 31 activates the start valve 32. The start valve 32 supplies compressed air to the tool body 20 from the chamber 33. The supplied compressed air causes the piston 23 to move downwards within the cylinder 22. The downward movement of the piston 23 causes the screwdriver head 24 to move downwards within the drive passage 27a.

[0030] like Figure 1 As shown, screws B are supplied one by one from the screw cartridge 40 into the driving passage 27a. Multiple screws B, for example, a connecting screw band made of resin, are loaded into the screw cartridge 40 in a wound state. The screw cartridge 40 is connected to the driving nose 27 via a screw feed mechanism 40a. Screws B are supplied into the driving passage 27a in conjunction with the driving action via the screw feed mechanism 40a. A screw B supplied into the driving passage 27a is impacted by a screwdriver head 24.

[0031] like Figure 1 As shown, an annular head rotating part 26 is clamped between the tool body 20 and the screwdriver nose 27. The head rotating part 26 is configured to rotate about the axis of the screwdriver head 24. The screwdriver head 24 is always inserted into the inner circumference of the head rotating part 26. The head rotating part 26 has the following functions: it allows the screwdriver head 24 to move up and down reciprocatingly, and it allows the screwdriver head 24 to rotate about the head axis (head fastening direction).

[0032] like Figure 1 As shown, the pneumatic motor 45 rotates the head rotating part 26 in the head tightening direction. A multi-stage gear system 28 is sandwiched between the head rotating part 26 and the pneumatic motor 45. The rotational power of the pneumatic motor 45 is transmitted to the head rotating part 26 through the gear system 28. As a result, the head rotating part 26 rotates about the axis of the screwdriver head 24. With the rotation of the head rotating part 26, the screwdriver head 24, which is inserted into its inner circumference, rotates integrally in the screw tightening direction.

[0033] like Figure 1 As shown, the downward movement of piston 23 causes screwdriver head 24 to move downward in drive passage 27a, and the head rotating part 26 rotates screwdriver head 24 in the head tightening direction. Thus, relative to the fastened part W, screw B is impacted and rotated, thereby tightening it.

[0034] like Figure 1As shown, the contact arm 27b is positioned at the lower part of the driving nose 27 in a manner that allows for vertical displacement. By pressing down the driving tool 1 with the contact arm 27b abutting against the fastening portion of the fastener W, the contact arm 27b moves upward relative to the driving nose 27. The driving action of the tool body 20 is performed based on both the activation operation that moves the contact arm 27b upward and the trigger 31 being pulled. This prevents accidental driving actions.

[0035] like Figure 1 As shown, a cover 50 that airtightly seals the chamber 33 is installed at the end of the handle portion 30. A connector 52 for connecting an air hose H is provided on the cover 50. The connector 52 is connected to the chamber 33 via a pressure regulating valve 51. Compressed air at an appropriate pressure is supplied to the chamber 33 through the pressure regulating valve 51.

[0036] like Figure 2 As shown, the pressure regulating valve 51 has a small-diameter cylindrical portion 51a and an intermediate cylindrical portion 51b. In the flow path formed in the small-diameter cylindrical portion 51a and the intermediate cylindrical portion 51b, a valve stem 51c, a valve body 51d, a valve seat 51e, a first spring 51f, and a second spring 51g are provided. Compressed air supplied to the pressure regulating valve 51 from the connector 52 causes the valve body 51d to overcome the force of the first spring 51f and move away from the valve seat 51e. Therefore, the compressed air is depressurized by the first spring 51f and supplied into the chamber 33.

[0037] like Figure 1 As shown, an overflow valve 2 is disposed adjacent to the pressure regulating valve 51 on the cover 50. The overflow valve 2 opens the chamber 33 to the atmosphere, thereby maintaining a suitable pressure within the chamber 33. Details of the overflow valve 2 are as follows... Figure 2 As shown below.

[0038] like Figure 2 As shown, the overflow valve 2 has a valve housing 7 having a flow path communicating with the chamber 33. A valve stem 3 movable along the flow path and a compression spring 8 applying force to the valve stem 3 towards the closed side are provided in the valve housing 7. An O-ring 6 is provided on the outer circumferential surface of the valve stem 3.

[0039] like Figure 2As shown, the valve box 7 has an inflow path 7a communicating with the chamber 33 and an outflow path 7b communicating with the downstream side of the inflow path 7a, and these serve as flow paths. The inflow path 7a extends in a straight line from one side of the cover portion 50, and its cross-sectional circle diameter has a smaller diameter than the inner circumferential surface 7f of the cylinder of the outflow path 7b. The outflow path 7b has a tapered surface 7d on its upstream side, whose diameter increases from upstream to downstream. The upstream portion of the tapered surface 7d is connected to the inner wall of the inflow path 7a. The outflow path 7b has an inner circumferential surface 7f on its downstream side, whose diameter is larger than that of the inflow path 7a. The diameter of the inner circumferential surface 7f is larger than the diameter of the downstream portion of the tapered surface 7d, therefore, a step is formed between the tapered surface 7d and the inner circumferential surface 7f. The step constitutes an abutment surface 7e that restricts the upstream movement of the stop portion 3d of the valve stem 3. A base 7c for a compression spring 8 is provided at the downstream end of the inner circumferential surface 7f of the cylinder. The inflow path 7a and the outflow path 7b are generally arranged in a straight line.

[0040] like Figure 3 As shown, from upstream to downstream, the valve stem 3 sequentially includes a sliding portion 3a, a stop portion 3d, and a leg portion 3e. The sliding portion 3a is approximately cylindrical, and a feed angle is formed on its outer peripheral surface. Figure 2 The O-ring 6 shown has an annular groove 4. A sliding portion 3a has a head 3b on the upstream side of the annular groove 4. The downstream side of the head 3b forms the upstream sidewall 4a of the annular groove 4. The sliding portion 3a has a sliding body portion 3c on the downstream side of the annular groove 4. The upstream side of the sliding body portion 3c forms the downstream sidewall 4b of the annular groove 4. Rounded corners are provided between the upstream sidewall 4a and the bottom surface 4c, and between the downstream sidewall 4b and the bottom surface 4c. The annular groove 4 has a bottom surface 4c, and the depth of the annular groove 4 is smaller than the diameter of the O-ring 6.

[0041] like Figure 3 , Figure 4 As shown, a venting groove 5 is formed on the downstream sidewall 4b. Multiple venting grooves 5 are formed on the downstream sidewall 4b, for example, four. The multiple venting grooves 5 are arranged at approximately equal intervals along the circumference. Each venting groove 5 has an inlet portion 5e near the bottom surface 4c of the annular groove 4 and extends radially. The inlet portion 5e is, for example, located near the end of the rounded corner between the bottom surface 4c and the downstream sidewall 4b. Each venting groove 5 has an outlet 5f on its radially outer side. The outlet 5f is located on the outer periphery of the local orthogonal section of the O-ring 6, opening into the inflow path 7a (or the outflow path 7b). The end of the outlet 5f opens on the outer peripheral surface of the sliding portion 3a. The width of the venting groove 5 is, for example, about half the wire diameter of the O-ring 6. The depth of the venting groove 5 is, for example, less than half the diameter of the O-ring 6.

[0042] like Figure 3 , Figure 4As shown, the stop portion 3d is approximately cuboid. The four corners of the stop portion 3d are chamfered in a curved shape. The four corners of the stop portion 3d are sized to abut against the contact surface 7e, and the interference between the four corners and the contact surface 7e restricts the upstream movement of the valve stem 3. The end of the compression spring 8 abuts against the downstream surface of the stop portion 3d.

[0043] like Figure 2 , Figure 3 As shown, the leg 3e is generally a hollow cylinder, and from upstream to downstream, it has a main body 3f, a middle abdomen 3g, and an end portion 3h. The diameters of the main body 3f, the middle abdomen 3g, and the end portion 3h decrease sequentially. The end portion 3h is always inserted into the through hole of the base 7c. This suppresses large-scale movement of the end of the leg 3e. The diameter of the middle abdomen 3g is larger than the through hole of the base 7c. Therefore, when the valve stem 3 moves downstream, the middle abdomen 3g abuts against the upper surface of the base 7c. This restricts the downstream movement of the valve stem 3. In the leg 3e, a plurality of slits 3i, for example, four, are formed along its entire axial length. This allows the leg 3e to elastically reduce its diameter. A compression spring 8 is fitted around the outer periphery of the leg 3e.

[0044] like Figure 2 As shown, the compression spring 8 is a helical spring. The first end of the upstream side of the compression spring 8 abuts against the downstream surface of the stop portion 3d. The second end of the downstream side of the compression spring 8 abuts against the upstream surface of the base 7c. The base 7c is fixed near the outlet of the discharge flow path 7b. Specifically, a pin hole 7g is formed near the outlet of the discharge flow path 7b. A spring pin (not shown) is inserted into the pin hole 7g, and the base 7c is fixed by the spring pin.

[0045] like Figure 2 As shown, the O-ring 6 is made of rubber and is annular. The O-ring 6 is annular and can be elastically expanded in diameter. In its natural state, the inner diameter of the O-ring 6 at the sliding portion 3a is smaller than the diameter of the bottom surface 4c of the annular groove 4. The outer diameter of the O-ring 6 is larger than the outer diameter of the sliding portion 3a (head 3b and sliding body 3c). Therefore, for the O-ring 6 fitted into the annular groove 4, the inner circumferential surface 6a abuts against the bottom surface 4c of the annular groove 4, and the outer circumferential surface 6b extends out of the annular groove 4. Thus, the O-ring 6 cooperates with the valve stem 3 to seal the inflow path 7a.

[0046] When the internal pressure of chamber 33 is below a predetermined value, the relief valve 2... Figure 5As shown by the imaginary line, the valve stem 3 presses the O-ring 6 tightly against the inflow passage 7a. This seals the inflow passage 7a. Here, the O-ring 6 is pressed against the inner wall of the inflow passage 7a and elastically deforms. As a result, the O-ring 6 elastically deforms towards the bottom surface 4c of the annular groove 4. Consequently, the area of ​​the O-ring 6 abutting against the bottom surface 4c of the annular groove 4 increases. Furthermore, the pressing pressure between the O-ring 6 and the bottom surface 4c of the annular groove 4 increases. When the internal pressure of the chamber 33 reaches a predetermined level, the valve stem 3 overcomes the force of the compression spring 8 and moves downstream.

[0047] like Figure 5 , Figure 6 As shown, the O-ring 6 moves downstream together with the valve stem 3, passing the inflow path 7a and reaching the conical surface 7d. Compared to the inner wall of the inflow path 7a, the force pressing the O-ring 6 radially inward on the conical surface 7d is smaller, therefore, the O-ring 6, due to its own elasticity, attempts to return to its original natural state. That is, the outer circumferential surface 6b of the O-ring 6 expands in diameter. As the O-ring 6 moves downstream, it is pressed downstream by the internal pressure of the inflow path 7a. Therefore, the downstream side of the O-ring 6 is pressed by the downstream sidewall 4b of the annular groove 4. On the other hand, the upstream side of the O-ring 6 moves away from the upstream sidewall 4a of the annular groove 4. At least when the O-ring 6 reaches the conical surface 7d, its upstream side moves away from the upstream sidewall 4a of the annular groove 4.

[0048] like Figure 5 , Figure 6 As shown, the outer peripheral surface 6b of the O-ring 6 abuts against the conical surface 7d. Therefore, compressed air flowing into the flow path 7a enters the inner peripheral surface 6a of the O-ring 6 through the space between the upstream side of the O-ring 6 and the upstream sidewall 4a of the annular groove 4. Then, the compressed air presses the inner peripheral surface 6a of the O-ring 6 radially outward, thereby expanding the diameter of the inner peripheral surface 6a of the O-ring 6. As a result, the inner peripheral surface 6a of the O-ring 6 moves away from the bottom surface 4c of the annular groove 4. Consequently, the compressed air flows downstream of the O-ring 6 through the space between the inner peripheral surface 6a of the O-ring 6 and the bottom surface 4c of the annular groove 4. That is, the compressed air flows into the inner peripheral chamber 4d enclosed by the bottom surface 4c of the annular groove 4, the downstream sidewall 4b, and the inner peripheral surface 6a of the O-ring 6. Thus, the compressed air aims to further expand the diameter of the O-ring 6. For this purpose, a venting groove 5 is formed in the valve stem 3.

[0049] For reference, use Figure 8 and Figure 9The case of the overflow valve 90 without the vent groove 5 is explained. Assuming the vent groove 5 is absent, there is no release space for the compressed air entering the inner circumferential chamber 4d. Therefore, the compressed air in the inner circumferential chamber 4d presses against the inner circumferential surface 6a of the O-ring 6. As a result, the O-ring 6 further expands in diameter. If the O-ring 6 moves away from the conical surface 7d or away from the downstream sidewall surface 4b of the annular groove 4, the compressed air is discharged towards the discharge path 7b, and the expansion of the O-ring 6 does not continue. However, if the O-ring 6 continues to expand in diameter without moving away from either side, then... Figure 9 This causes the O-ring 6 to shift axially relative to the annular groove 4. Therefore, in this situation, the operator must re-insert the O-ring 6 into the valve stem 3, resulting in an interruption of the operation.

[0050] On the other hand, such as Figure 6 The vent groove 5 shown allows compressed air entering the inner circumferential chamber 4d to be discharged to the discharge path 7b. Therefore, it prevents the O-ring 6 from expanding due to the compressed air pressing against the inner circumferential surface 6a. During this period, the valve stem 3 moves further downstream, reaching... Figure 5 The position is shown by the solid line. Therefore, on the radially outer side of the O-ring 6, the inflow path 7a and the outflow path 7b are connected, and the chamber 33 is open to the atmosphere. Therefore, the axial misalignment of the O-ring 6 relative to the annular groove 4 is suppressed.

[0051] As mentioned above, Figure 1 , Figure 2 As shown, the injection tool 1 has a chamber 33 for storing compressed air and an overflow valve 2 disposed in the chamber 33. The overflow valve 2 has an inflow passage 7a communicating with the chamber 33 and a discharge passage 7b formed downstream of the inflow passage 7a and having a diameter larger than the inflow passage 7a. Figure 5 As shown, the valve stem 3 moves along the inflow path 7a. An O-ring 6 is fitted in the annular groove 4 on the outer periphery of the valve stem 3 to seal the inflow path 7a. A venting path (e.g., venting grooves 5a to 5d) is formed on the valve stem 3. The venting path has an inlet 5e opening in the inner peripheral chamber 4d and an outlet 5f opening in the discharge path 7b, so that when compressed air enters the inner peripheral chamber 4d between the wall of the annular groove 4 and the inner peripheral surface 6a of the O-ring 6 due to the internal pressure of the chamber 33, the compressed air is discharged from the inner peripheral chamber 4d to the discharge path 7b.

[0052] Therefore, the O-ring 6 moves together with the valve stem 3 to the discharge flow path 7b and expands in diameter. Compressed air entering the inner circumferential chamber 4d further promotes the expansion of the O-ring 6. Simultaneously, the compressed air is discharged from the inner circumferential chamber 4d to the discharge flow path 7b through the venting path. Thus, the expansion of the O-ring 6 is prevented from disengaging from the valve stem 3. As a result, the recovery operation of re-embedding the O-ring 6 into the valve stem 3 for reuse of the relief valve 2 is eliminated.

[0053] like Figure 4 As shown, the venting path is formed by a groove (e.g., venting groove 5a) formed on the downstream side wall 4b of the O-ring 6, which supports the compressed air downstream of the annular groove 4. The groove extends radially in the valve stem 3. Therefore, compared to a configuration in which a through hole is formed in the valve stem 3 and the inner peripheral chamber 4d is connected to the discharge flow path 7b through the through hole, the venting path can be obtained more easily.

[0054] like Figure 4 As shown, multiple venting grooves (e.g., four venting grooves 5a to 5d) are formed on the downstream sidewall 4b of the annular groove 4. Therefore, compared to the case where only one groove is formed, the compressed air entering the inner peripheral chamber 4d is rapidly discharged to the discharge flow path 7b. Thus, the expansion of the O-ring 6 can be suppressed more effectively.

[0055] like Figure 1 As shown, the injection tool 1 has a handle 30 that is held by the user and houses the chamber 33. An overflow valve 2 is provided on the end face of the handle 30. Therefore, the direction of compressed air discharged from the overflow valve 2 is axial towards the handle 30. Therefore, even when compressed air is discharged from the overflow valve 2, the chance of compressed air coming into contact with the operator is reduced.

[0056] like Figure 1 As shown, the drive tool 1 has a pressure regulating valve 51, which reduces the pressure of compressed air from the outside and supplies it to the chamber 33. The pneumatic tool has a drive tool body 20, which includes a screwdriver (e.g., screwdriver head 24) for driving fasteners (e.g., screw B) using compressed air from the chamber 33. Therefore, the compressed air from the outside is reduced to an appropriate pressure for operating the screwdriver via the pressure regulating valve 51.

[0057] like Figure 1 , Figure 2 As shown, an O-ring 6 is fitted into the annular groove 4 on the outer periphery of the valve stem 3 to seal the inflow path 7a. It has an O-ring detachment suppression structure (e.g., vent grooves 5a to 5d) that prevents the O-ring 6 from detaching from the valve stem 3 during its journey across the inflow path 7a and towards the discharge path 7b due to the internal pressure of the chamber 33.

[0058] Therefore, according to the O-ring detachment suppression structure, the O-ring 6 will not expand radially or detach from the valve stem 3. Thus, there is no need for the restoration operation of re-embedding the O-ring 6 into the valve stem 3 for reuse of the relief valve 2.

[0059] use Figure 7 Embodiment 2 will be described. Embodiment 2 is formed almost identically to Embodiment 1 described above. The insertion tool 1 in Embodiment 2 replaces... Figure 6 The valve stem 3 shown has Figure 7 The valve stem 70 is shown.

[0060] like Figure 7 As shown, a vent hole 75 is formed on the downstream sidewall 4b of the valve stem 70. The vent hole 75 is, for example, a drilled hole extending from the downstream sidewall 4b to the outer peripheral surface of the sliding body 3c. The inlet 75e of the vent hole 75 is located near the bottom surface 4c of the annular groove 4. Thus, the inlet 75e opens into the inner peripheral chamber 4d at an inner peripheral side closer to the center of the local orthogonal section of the O-ring 6. The inlet 75e is, for example, located near the end point of the fillet between the bottom surface 4c and the downstream sidewall 4b. The outlet 75f of the vent hole 75 opens on the outer peripheral surface of the sliding body 3c. Thus, the inlet 75e opens into the flow paths 7a and 7b at an outer peripheral side closer to the center of the local orthogonal section of the O-ring 6.

[0061] Alternatively, it can be replaced by the form described below. The vent 75 only needs to connect the inner peripheral chamber 4d with the flow paths 7a and 7b, and the orthogonal cross-sectional shape can be, for example, an ellipse or a polygon. To further increase the amount of compressed air discharged, multiple vents 75 can also be formed on the downstream side wall 4b, for example, four.

[0062] like Figure 1 As shown, the driving tool 1 uses compressed air to impact and rotate the screw B relative to the fastener W, thus tightening it. Alternatively, a pneumatic nail gun can be used. That is, the driving tool 1 can be any pneumatic tool with an overflow valve in the chamber; other examples include pneumatic impact screwdrivers, pneumatic hammers, and pneumatic wrenches.

[0063] like Figure 6 As shown, the end of the outlet 5f of the venting groove 5 opens on the outer peripheral surface of the sliding part 3a. Alternatively, the end of the outlet 5f may open on the downstream side wall 4b. That is, it can be that the outlet is located on the outer peripheral side of the flow path 7a, 7b, closer to the center of the local orthogonal section of the O-ring 6. Alternatively, the venting groove 5 can extend radially from the inlet 5e and cross the center, with the end of the outlet 5f opening on the downstream side wall 4b.

[0064] like Figure 4As shown, the venting groove 5 has four venting grooves 5a to 5d. Alternatively, only one venting groove 5a can be formed. In addition to the four venting grooves 5a to 5d, grooves can also be formed to form five or more venting grooves 5.

[0065] like Figure 2 As shown, the injection tool 1 has a chamber 33 with a pressure regulating valve 51 installed together with the relief valve 2. Alternatively, the chamber 33 may only have the relief valve 2 installed. That is, compressed air is supplied directly to the chamber 33 from an external air supply source. The relief valve 2 operates when the chamber 33 becomes under abnormal pressure due to a faulty air supply source, etc.

[0066] like Figure 3 As shown, the vent groove 5 is formed on the wall surface 4b of the annular groove 4 of the valve stem 3. Alternatively, the vent groove 5 can be formed on the conical surface 7d of the discharge flow path 7b in the valve box 7. The vent groove 5 formed on the conical surface 7d prevents the formation of the inner circumferential chamber 4d itself. As a result, the O-ring 6 will not be compressed and enlarged by the compressed air entering the inner circumferential chamber 4d. For example, the vent groove 5 extends from the upstream portion of the conical surface 7d towards the downstream portion, with the inlet portion 5e opening in the inflow flow path 7a and the outlet portion 5f opening in the contact surface 7e, functioning as an O-ring detachment suppression structure.

Claims

1. A compressed air tool, characterized in that, have: A chamber containing compressed air; and An overflow valve is disposed in the chamber. The overflow valve has: An inflow path, which communicates with the chamber; An outlet flow path is formed downstream of the inflow flow path and has a larger diameter than the inflow flow path; The valve stem moves along the inflow path; An O-ring is fitted into the annular groove on the outer periphery of the valve stem and seals the inflow path; as well as The venting path is formed in the valve stem. The annular groove has a bottom surface located on the inner circumference of the O-ring and a downstream side wall surface that supports the O-ring from the downstream side of the compressed air. The discharge flow path has a tapered surface that expands in diameter from the downstream end of the inflow flow path toward its own downstream side. When the O-ring is located in the inflow path, the outer circumferential surface of the O-ring abuts against the inner wall of the inflow path over its entire circumference, and the inner circumferential surface of the O-ring abuts against the bottom surface over its entire circumference. The pneumatic tool has an O-ring detachment suppression structure that prevents the O-ring from radially expanding and detaching from the valve stem when the O-ring, due to the internal pressure of the chamber, crosses the inflow path and moves towards the discharge path. The O-ring detachment suppression structure includes: an venting path located on the downstream sidewall and having an inlet opening towards the inner circumferential chamber between the bottom surface and the inner circumferential surface of the O-ring and an outlet opening towards the discharge flow path; a conical surface for the outer circumferential surface of the O-ring to abut against on the entire circumference; and a downstream sidewall for the downstream side surface of the O-ring to abut against.

2. The air compressor tool according to claim 1, characterized in that, The venting path is formed by a groove formed on the downstream sidewall, which extends radially on the valve stem.

3. The air compressor tool according to claim 2, characterized in that, A plurality of grooves are formed on the downstream sidewall of the annular groove.

4. The air compressor tool according to claim 3, characterized in that, It has: a handle extending laterally from the side of the tool body, which is held by the user and houses the chamber. The overflow valve is located on the end face of the handle on the side opposite to the tool body.

5. The air compressor tool according to claim 4, characterized in that, have: A pressure regulating valve that reduces the pressure of the compressed air from the outside and supplies it to the chamber; and The tool body is equipped with a screwdriver that uses compressed air from the chamber to drive in fasteners.

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