Pneumatic nail gun

Abstract

Disclosed is a pneumatic nail gun, which relates to a power tool, including a gun body and a nail feeder, inside the gun body being provided a cylinder assembly, a drive assembly and a locking assembly, the cylinder assembly including a first cylinder provided with a first piston, a second cylinder provided with a second piston, and a striker, the second cylinder including a cylinder barrel, the second piston being disposed in the cylinder barrel, the second piston and the striker having an initial position and a nail-striking position; the cylinder barrel has a vent hole, the vent hole being at least locally higher than a top surface of the second piston at the initial position, allowing for compressed air in the first cylinder to flow through the vent hole into the second cylinder to act on the second cylinder so that the second piston drives the striker to move from the initial position to the nail-striking position. The disclosure increases the active contact area of the compressed air acting on the second piston, so that the second piston may achieve a larger initial action force, increasing the initial movement speed of the second piston driving the striker to move downward, thereby increasing the movement speed of the second piston driving the striker upon nail driving.

Description

FIELD

[0001] The subject matter described herein relates to a power tool, and more particularly relates to a pneumatic nail gun.BACKGROUND

[0002] A nail gun is a handheld nail-driving tool that uses a fast-moving striker to drive nails into wood or other materials. Based on various sources of driving force, nail guns are divided into electric nail guns, pneumatic nail guns, and manual nail guns, etc. Existing nail guns generally adopt a dual-cylinder structure, in which when a large piston in the larger cylinder moves to compress air in the larger cylinder to a predetermined extent, a piston in the smaller cylinder is released, causing the compressed air in the larger cylinder to flow through a gas flow passage into the smaller cylinder to push the small piston in the smaller cylinder to move rapidly, and then the fast-moving small piston drives the striker to move synchronously, the fast-moving striker driving the nail into an object such as wood, whereby nail driving is completed. However, the existing dual-cylinder pneumatic nail gun has a complex air flow passage structure through which compressed air flows from the larger cylinder into the smaller cylinder, which is highly demanding on airtightness of concerned components; in addition, due to a long compressed air flow path and a small active contact area where the compressed air acts on the small piston, the initial action force received by the small piston is insufficient, which launches a low initial movement speed, so that the small piston obtains a low velocity in driving the striker to nail, leading to an insufficient nail penetration depth; moreover, the low driving velocity cannot drive a nail effectively into a harder object, which would deteriorate user experience.SUMMARY

[0003] To overcome the drawbacks of conventional technologies, a pneumatic nail gun is provided; by setting vent holes on a cylinder barrel of a second cylinder, compressed air in the first cylinder may directly flow through the vent holes into the second cylinder to act on a second piston, which effectively increases a nail penetration depth and effectively drives a nail into a harder object, whereby user experience is improved.

[0004] A pneumatic nail gun described herein comprises a gun body and a nail feeder, inside the gun body being provided a cylinder assembly, a drive assembly and a locking assembly, the cylinder assembly comprising a first cylinder provided with a first piston, a second cylinder provided with a second piston, and a striker driven by the second piston, the first piston being driven by the drive assembly and having a vent position and a compressed position, the second cylinder being provided in the first cylinder and passing through the first piston, the second cylinder comprising a cylinder barrel, the second piston being disposed in the cylinder barrel, the second piston and the striker having an initial position and a nail-striking position, the locking assembly limiting the second piston to the initial position during a process of the first piston moving from the vent position to the compressed position, wherein the cylinder barrel has a vent hole providing communication between an inside of the first cylinder and an inside of the second cylinder, the vent hole being at least locally higher than a top surface of the second piston at the initial position, allowing for compressed air in the first cylinder to flow through the vent hole into the second cylinder to act on the second cylinder so that the second piston drives the striker to move from the initial position to the nail-striking position.

[0005] In some implementations, at least 50% of an area of the vent hole is set higher than the top surface of the second piston at the initial position.

[0006] In some implementations, an entirety of the vent hole is set higher than the top surface of the second piston at the initial position.

[0007] In some implementations, a plurality of vent holes are provided at intervals along a circumferential direction of the cylinder barrel; and / or, the vent holes are shaped into at least one of round holes, square holes, rectangular holes, elliptical holes, arc-shaped holes, and triangular holes.

[0008] In some implementations, a sealing ring axially positioned is sleeved circumferentially on the second piston, and the vent hole is set higher than the sealing ring at the initial position.

[0009] In some implementations, a shock-absorbing cushion is provided on the top surface of the second piston, the shock-absorbing cushion being provided with a grooved structure configurable for the compressed air to flow through.

[0010] In some implementations, an outside diameter of the shock-absorbing cushion is smaller than that of the second piston; and / or, the vent hole is set locally higher than a top surface of the shock-absorbing cushion at the initial position.

[0011] In some implementations, the grooved structure comprises a plurality of radial grooves distributed at intervals in a circumferential direction and a plurality of circumferential grooves providing communication between the radial grooves.

[0012] In some implementations, the locking assembly comprises a fixed base disposed in the first cylinder, a locking bush disposed on top of the cylinder barrel and inserted in the fixed base, a lock core disposed on the second piston and insertable in the locking bush, and a sliding block slidably disposed on the fixed base and fitted with the lock core to limit the second piston to the initial position, a sealing grease being filled in a fitting interstice between the locking bush and the fixed base.

[0013] In some implementations, the fixed base is provided with a sliding groove in which the sliding block is mounted, a top side of the sliding groove being open, the sliding block being mounted in the sliding groove via a cover piece, an elastic pad being arranged between a top portion of the fixed base and a top wall of the first cylinder; or, the fixed base is provided with a sliding groove in which the sliding block is mounted and a groove cover configured to cover the sliding groove, a top side of the sliding groove being open, the sliding block being mounted in the sliding groove via a cover piece, the groove cover being configured to cover the top side of the sliding groove, an elastic sealing rib being arranged between a circumferential exterior wall of the groove cover and a circumferential interior wall of the sliding groove; or, the fixed base is provided with a sliding groove in which the sliding block is mounted, a bottom side of the sliding groove being open, the sliding block being mounted in the sliding groove via a cover piece, the cover piece being fixed together with the fixed base.

[0014] With the technical solutions noted supra, the present disclosure offers the following benefits: 1. The pneumatic nail gun described herein is set with a vent hole on the cylinder barrel of the second cylinder, the vent hole providing communication between the insides of the two cylinders. The compressed air in the first cylinder may directly flow through the vent hole into the second cylinder to act on the second piston, whereby an active contact area of the compressed air acting on the second piston is reasonably increased, so that the second piston may obtain a large initial action force, which increases an initial movement speed of the second piston released by the locking assembly to drive the striker to move downward, thereby increasing a movement speed of the second piston driving the striker to drive a nail; this achieves a greater nail penetration depth and enables the nail to be penetrated into a hard object, whereby user experience is improved. In addition, since the compressed air in the first cylinder may directly flow into the second cylinder via the vent hole to act on the second piston, there eliminates a need of setting on the locking assembly or another member a passage structure through which the compressed air flows from the first cylinder into the second cylinder, which lowers structural difficulty and airtight requirements of concerned members. 2. When the second piston is disposed at the initial position, at least 50% of the area of the vent hole is set higher than the top surface of the second piston; or, the entirety of the vent hole is set higher than the top surface of the second piston, which guarantees the amount of compressed air flowing through the vent hole into the second cylinder, so that the second piston and the striker may obtain an enough initial movement speed, whereby the nail driving effect is enhanced. 3. A plurality of vent holes are preferably arranged circumferentially at intervals, so that the compressed air in the first cylinder may flow rapidly through the vent holes in the second cylinder to act on the second piston, which enhances the movement speed of the second piston driving the striker to move from the initial position to the nail-striking position, thereby improving the nail driving effect. 4. The vent holes may adopt a uniform shape, or may adopt various shapes; by reasonably setting the structural patterns of the vent holes, the machining difficulty of the vent holes is lowered, which facilitates promotion of production efficiency. 5. When the second piston is disposed at the initial position, the vent hole is set higher than the sealing ring on the second piston so that the compressed air flowing through the vent hole into the second cylinder may effectively act on the second piston, which prevents direct discharge of the compressed air flowing through the vent hole into the second cylinder so that the compressed air can effectively act on the second piston; this enhances the effect of the compressed air acting on the second piston and enhances the nail driving effect. 6. By setting a grooved structure on the top surface of the shock-absorbing cushion, when the second piston is disposed at the initial position, the compressed air flowing into the second cylinder may flow in the grooved structure, which further increases the active contact area of the compressed air acting on the second piston, thereby further increasing the initial action force launched by the second piston to increase the movement speed of the striker in driving a nail, whereby the nail driving effect is enhanced. 7. Since the outside diameter of the shock-absorbing cushion is smaller than that of the second piston, the compressed air flowing through the vent hole into the second cylinder may directly and effectively act on the top surface of the second piston, which guarantees the initial movement speed of the second piston and the striker. When the second piston is disposed at the initial position, the vent hole is locally higher than the top surface of the shock-absorbing cushion, so that the compressed air flowing through the vent hole into the second cylinder may flow rapidly in the grooved structure, which enhances the effect of the compressed air acting on the second piston. 8. A sealing grease is filled in the fitting interstice between the locking bush and the fixed base; the sealing grease realizes airtightness between the locking bush and the fixed base, preventing leakage of compressed air from an assembly interstice between the locking bush and the fixed base, which would otherwise mitigate the action effect of the compressed air acting on the second piston. 9. An elastic pad is arranged between the top portion of the fixed base and the top wall of the first cylinder, the elastic pad achieving airtightness at the top side of the fixed base. Or, a groove cover is provided to cover the sliding groove, and a sealing rib is arranged between the groove cover and the sliding groove; the sealing rib implements airtightness at the top side of the sliding groove. Or, the bottom side of the sliding groove is open, and the cover piece is fixed together with the fixed base, which avoids grooving at the top portion of the fixed base as much as possible. Reasonable setting of the mounting structure of the sliding block and the sealing structure of the fixed base prevents leakage of the compressed air in the first cylinder from the assembly interstice, so that the air pressure of the compressed air in the first cylinder would not drop, ensuring the effect of the compressed air acting on the second piston. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Fig. 1 is an overall view of a pneumatic nail gun according to a first implementation; Fig. 2 is an internal structural diagram of a gun body of the pneumatic nail gun according to the first implementation; Fig. 3 is a structural diagram of a cylinder assembly of the pneumatic nail gun according to the first implementation; Fig. 4 is a partial structural view of the cylinder assembly of the pneumatic nail gun according to the first implementation; Fig. 5 is a partial structural view of a second piston at an initial position in the pneumatic nail gun according to the first implementation; Fig. 6 is a structural view of the second piston in the pneumatic nail gun according to the first implementation; Fig. 7 is a structural view of a cylinder barrel of the second cylinder in the pneumatic nail gun according to the first implementation; Fig. 8 is a structural view of fitting between a cylinder barrel and an elastic valve sleeve of the second cylinder in the pneumatic nail gun according to the first implementation; Fig. 9 is a structural view of fitting between the second cylinder and a locking assembly in the pneumatic nail gun according to the first implementation; Fig. 10 is an exploded view of a sliding block and a cover piece of the locking assembly in the pneumatic nail gun according to the first implementation; Fig. 11 is a structural view of a drive assembly in the pneumatic nail gun according to the first implementation; Fig. 12 is a partial structural view of a second piston at an initial position in a pneumatic nail gun according to a second implementation; Fig. 13 is a partial structural view of a locking assembly in a pneumatic nail gun according to a third implementation.

[0016] In the drawings: 100 - gun body; 200 - nail feeder; 300 - cylinder assembly; 310 - first cylinder; 311 - first piston; 312 - cylinder housing; 313 - cylinder base; 314 - first sealing ring; 315 - pin rod; 316 - first through-hole; 320 - second cylinder; 321 - second piston; 322 - cylinder barrel; 322a - narrowed opening portion; 323 - vent hole; 324 - head plug; 325 - second sealing ring; 326 - avoidance hole; 327 - second through hole; 330 - striker; 340 - shock-absorbing cushion; 341 - radial groove; 342 - circumferential groove; 350 - rod body; 360 - elastic valve sleeve; 400 - drive assembly; 410 - electric motor; 420 - speed reducer; 421 - output shaft; 430 - crank handle; 440 - connecting rod; 500 - locking assembly; 510 - fixed base; 511 - sliding groove; 512 - avoidance recess; 513 - insertion hole; 520 - locking bush; 521 - notch; 530 - lock core; 531 - locking groove; 540 - sliding block; 541- stepped portion; 542 - through slot; 543 - second bevel; 550 - nut; 560 - elastic pad; 570 - locking spring; 580 - ejector pin; 581 - first bevel; 591 - cover piece, 592 - groove cover; 593 - sealing rib; 594 - airtight ring; 600 - enclosure; 610 - grip portion.DETAILED DESCRIPTION OF EMBODIMENTS

[0017] Hereinafter, the disclosure will be further described through specific implementations with reference to the accompanying drawings. It is understood that the orientational or positional relationships indicated by the terms "upper," "lower," "left," "right," "longitudinal," "transverse," "inner," "outer," "vertical," "horizontal," "top," and "bottom" refer to those orientational and positional relationships illustrated in the drawings, which are intended only for facilitating description of the disclosure and simplifying relevant depictions, but not for indicating or implying that the devices or elements compulsorily possess such specific orientations or are compulsorily configured and operated with the specific orientations; therefore, such terms should not be construed as limitations to the disclosure.First Implementation

[0018] Referring to Figs. 1 and 11, a pneumatic nail gun according to a first implementation of the disclosure comprises a gun body 100 and a nail feeder 200, inside the gun body 100 being provided a cylinder assembly 300, a drive assembly 400, and a locking assembly 500, the cylinder assembly 300 comprising a first cylinder 310 provided with a first piston 311, a second cylinder 320 provided with a second piston 321, and a striker 330 driven by the second piston 321; the first piston 311 being driven by the drive assembly 400 and having a vent position and a compressed position, the second cylinder 320 being disposed in the first cylinder 310 and passing through the first piston 311, the second cylinder 320 comprising a cylinder barrel 222, the second piston 321 being disposed in the cylinder barrel 322, the second piston 321 and the striker 330 having an initial position and a nail-striking position, the locking assembly 500 limiting the second piston 321 to the initial position during a process of the first piston 311 moving from the vent position to the compressed position. The cylinder barrel 322 is provided with a vent hole 323 providing communication between the inside of the first cylinder 310 and the inside of the second cylinder 320, the vent hole 323 being at least locally higher than a top surface of the second piston 321 at the initial position, allowing the compressed air in the first cylinder 310 to flow through the vent hole 323 into the second cylinder 320 to act on the second piston 321 so that the second piston 321 drives the striker 330 to move from the initial position to the nail-striking position.

[0019] The compressed air in the first cylinder 310 may directly flow through the vent hole 323 into the second cylinder 320 to act on the second piston 321, whereby an active contact area of the compressed air acting on the second piston 321 is reasonably increased, so that the second piston 321 may achieve a larger initial action force, which increases an initial movement speed of the second piston 321 released by the locking assembly 500 to drive the striker 330 to move downward, thereby increasing a movement speed of the second piston 321 driving the striker 330 to move from the initial position to the nail-striking position; this achieves a greater nail penetration depth and enables the nail to be penetrated into a hard object, thereby improving user experience.

[0020] Referring to Figs. 3 and 4, in this implementation, the first cylinder 310 comprises a hollow cylinder housing 312 and a cylinder base 313 disposed at a bottom end of the cylinder housing 312, a first sealing ring 314, which is axially positioned, being sleeved circumferentially on the first piston 311 via a slot, the first piston 311 being driven by the drive assembly 400 to be movable up and down in the first cylinder 310. The second cylinder 320 is eccentrically fixed on the cylinder base 313; the second cylinder 320 further comprises a head plug 324 inserted in a bottom end of the cylinder barrel 322; a through port eccentrically disposed and fitted with the cylinder barrel 322 is provided on the first piston 311; the cylinder barrel 322 of the second cylinder 320 passes through the first piston 311 via the through port, i.e., the first piston 311 is movable up and down relative to the second cylinder 320; an O-shaped sealing ring configured to seal the first piston 311 and the cylinder barrel 322 is arranged on an inner wall of the through port.

[0021] Referring to Fig. 5, a second sealing ring 325, which is axially positioned, is sleeved circumferentially on the second piston 321 via a slot, the second sealing ring 325 enabling circumferentially seal-fitting between the second piston 321 and the cylinder barrel 322. To allow for the compressed air flowing into the second cylinder 320 to effectively act on the second piston 321, when the second piston 321 is located at the initial position, the vent hole 323 is set higher than the second sealing ring 325 also at the initial position, which prevents the compressed air flowing through the vent hole 323 into the second cylinder 320 from being directly discharged, so that the compressed air can effectively act on the second piston 321.

[0022] Referring to Fig. 7, a narrowed opening portion 322a, which is formed integrally with the cylinder barrel 322, is provided on top of the cylinder barrel 322, the vent hole 323 being disposed at an upper end of the cylinder barrel 322 and lower than the narrowed opening portion 322a. To allow for the compressed air in the first cylinder 310 to flow rapidly through the vent hole 323 into the second cylinder 320 to act on the second piston 321, a plurality of vent holes 323 are arranged at intervals in the circumferential direction of the cylinder barrel 322. In this implementation, the vent holes 323 are round holes and exemplarily distributed at even internals in the circumferential direction of the cylinder barrel 322. It may be understood that, the vent holes 323 may also be set as other reasonable shapes such as square holes, rectangular holes, elliptical holes, arcuate holes, and triangular holes; of course, various shapes of vent holes 323 may be arranged simultaneously, e.g., two, three, or any number of shapes of holes among the circular holes, the square holes, the rectangular holes, the elliptical holes, the arc-shaped holes, and the triangular holes may be adopted simultaneously; the shapes of the holes are not limited here. In addition, the vent holes 323 may also be arranged at uneven intervals, i.e., the arc length between centers of one pair of adjacent vent holes 323 is different from that between the centers of another pair.

[0023] Referring to Fig. 5, to guarantee the amount of the compressed air flowing through the vent hole 323 into the second cylinder 320, when the second piston 321 is disposed at the initial position, at least 50% of the area of the vent hole 323 is higher than the top surface of the second piston 321. In this implementation, when the second piston 321 is disposed at the initial position, it is preferable that an entirety of the vent hole 323 is higher than the top surface of the second piston 321; a height difference Δ h is present between the lowest point of the vent hole 323 and the top surface of the second piston 321 so that 100% of the area of the vent hole 323 is higher than the top surface of the second piston 321 at the initial position. It may be understood that, Δ h may be set to a reasonable value such as 0.2mm, 0.5mm, 0.7mm, 1mm, 1.2mm, 1.5mm, 1.7mm, and 2mm. Of course, when the second piston 321 is disposed at the initial position, the lowest point of the vent hole 323 may also be set flush with the top surface of the second piston 321. Or, when the second piston 321 is disposed at the initial position, the lowest point of the vent hole 323 may also be set slightly lower than the top surface of the second piston 321 such that the vent hole 323 is locally higher than the top surface of the second piston 321 with a proportion of the area of the vent hole 323 higher than the top surface of the second piston 321 being set to a reasonable value such as 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, and 99%.

[0024] To mitigate the shock imposed by the second piston 321 reset upward to the initial position upon the locking assembly 500, a shock-absorbing cushion 340 is arranged on the top surface of the second piston 321, the shock-absorbing cushion 340 being provided with a grooved structure for the compressed air to flow through. Referring to Fig. 6, the outside diameter of the shock-absorbing cushion 340 is exemplarily smaller than that of the second piston 321 so that the compressed air flowing through the vent hole 323 into the second cylinder 320 may directly and effectively act on the top surface of the second piston 321. The grooved structure comprises a plurality of radial grooves distributed at intervals in a circumferential direction and a plurality of circumferential grooves 342 providing communication between the radial grooves 341 so that the compressed air flowing through the grooved structure into the second cylinder 320 may uniformly act on the top surface of the second piston 321. It may be understood that, the circumferential grooves 342 may adopt arc-shaped grooves or annular grooves; two, three, or other reasonable numbers of circles of circumferential grooves 342 may be arranged at intervals from the inside to the outside as per the size of the shock-absorbing cushion 340. Of course, the grooved structure may also be set to another reasonable structure.

[0025] Referring to Fig. 5, to allow for the compressed air flowing through the vent hole 323 into the second cylinder 320 to flow quickly in the grooved structure, when the second piston 321 is disposed at the initial position, the vent hole 323 is set locally higher than the top surface of the shock-absorbing cushion 340 disposed also at the initial position, so that the vent hole 323 locally lower than the top surface of the shock-absorbing cushion 340 is disposed substantially at a same height as the grooved structure; consequently, the compressed air flowing through the vent hole 323 into the second cylinder 320 may directly flow into the grooved structure. It may be understood that, when the second piston 321 and the shock-absorbing cushion 340 are disposed at the initial position, a proportion of the area of the vent hole 323 higher than the top surface of the shock-absorbing cushion 340 may be set to a reasonable value such as 40%, 45%, 50%, 55%, and 60%.

[0026] Referring to Figs. 3, 5, and 9, the locking assembly 500 comprises a fixed base 510, a locking bush 520, a lock core 530, a sliding block 540, a nut 550, and a locking spring 570, the fixed base 510 being secured to a top end in the first cylinder 310 and disposed on top of the second cylinder 320, an elastic pad 560 being arranged between the fixed base 510 and a top wall of the cylinder housing 312, an avoidance hole 326 configured for the locking bush 520 to pass through being formed on the narrowed opening portion 322a of the cylinder barrel 322, an axial section of the locking bush 520 being formed substantially as a hollow inverted-T shape, a plate-like portion of the locking bush 520 being disposed in the first cylinder 310 and abutting against the narrowed opening portion 322a in a vertical direction, a columnar portion of the locking bush 520 passing through the fixed base 510 and fastened tightly on the top wall of the cylinder housing 312 via the nut 550. A rod body 350 is provided at a top end of the striker 330, a top end of the rod body 350 being inserted in the second piston 321, a lower end of the lock core 530 being inserted in the second piston 321 and securely fastened with the rod body 350 via a screw, whereby the lock core 530, the rod body 350, and the second piston 321 are fixed together; the shock-absorbing cushion 340 is located at an outer periphery of the lock core 530. A circle of locking groove 531 fitted with the sliding block 540 is arranged at an upper portion of the lock core 530, and the fixed base 510 is arranged with a sliding groove 511 extending along a certain radial direction, the sliding block 540 and the locking spring 570 being disposed in the sliding groove 511; as illustrated in Figs. 9 and 10, a stepped portion 541 fitted with the locking groove 531 to limit the second piston 321 to the initial position is provided at one end of the sliding block 540 facing the lock core 530; the locking bush 520 is provided with a notch 521 for avoiding the sliding block 540. When the locking spring 570 is disposed in the compressed state, one end thereof abuts against a groove wall of the sliding groove 511, and the opposite end thereof abuts against the sliding block 540; when the locking spring 570 is disposed in the normal state, the sliding block 540 is pushed against the lock core 530 so that the stepped portion 541 and the locking groove 531 are disposed in a locked state. In this implementation, the top side of the sliding groove 511 is opened; the sliding block 540 and the lock core 530 are both metal pieces; the fixed base 510 is a plastic piece; the locking block 540 is disposed in the sliding groove 511 via a metallic cover piece 591.

[0027] The fixed base 510 is provided with an insertion hole 513 for the columnar portion of the locking bush 520 to pass through, the insertion hole 513 and the columnar portion of the locking bush 520 being interstice-fitted. In this implementation, a sealing grease is filled in the fitting interstice between the locking bush 520 and the fixed base 510, the sealing grease implementing airtightness between the locking bush 520 and the fixed base 510, which prevents leakage of compressed air from the fitting interstice between the locking bush 520 and the fixed base 510, without diminishing the action effect against the second piston.

[0028] The fixed base 510 is secured on the top wall of the cylinder housing 312 via a bolt; the elastic pad 560 is tightly clamped between the top surface of the fixed base 510 and the top wall of the cylinder housing 312; the elastic pad 560 implements airtightness at the top side of the fixed base 510, which prevents leakage of the compressed air in the first cylinder 310 from an assembly interstice of the locking assembly, without diminishing the air pressure of the compressed air in the first cylinder; this guarantees the action effect of the compressed air against the second piston 321.

[0029] Referring to Fig. 3, to allow for the locking assembly 500 to release the second piston 321 timely, the locking assembly 500 further comprises an ejector pin 580 which is disposed on the first piston 311 and configured to unlock the locking assembly 500; a first bevel 581 is provided at one side of the ejector pin 580 facing away from the axial center of the first piston 311; the sliding block 540 is provided with a through slot 542 in which the ejector pin 580 is inserted; a second bevel 543 parallel to the first bevel 581 is provided at one side of the through slot 542 facing away from the axial center of the first piston 311; the fixed base 510 is provided with an avoidance recess 512 configured to avoid the ejector pin 580; the cover piece 591 is provided with a recess for avoiding the ejector pin 580. During a process of the first piston 311 moving upward from a vent position to a compressed position, the ejector pin 580 moves upward synchronously with the first piston 311 and is then inserted through the avoidance recess 512 into the through slot 542 of the sliding block 540, whereby the first bevel 581 and the second bevel 543 abut such that the sliding block 540 is forced to move in a direction away from the lock core 530, with the locking spring 570 being compressed under stress; as such, the sliding block 540 migrates out of the locking groove 531 of the lock core 530 to implement unlocking.

[0030] Referring to Fig. 2, the gun body 100 comprises an enclosure 600, a grip portion 610 being formed on the enclosure 600. The axial direction of the drive assembly 400 is set substantially perpendicular to the axial direction of the cylinder assembly 300; the drive assembly 400 comprises an electric motor 410 and a speed reducer 420 which are fixed together. Referring to Figs. 3 and 11, the speed reducer 420 comprises an output shaft 421, a bottom end of the output shaft 421 projecting into the cylinder base 313 and being sleeved with a crank handle 430; a pin rod 315 is disposed in the first piston 311; a connecting rod 440 is arranged between the pin rod 315 and the crank handle 430, a top end of the connecting rod 440 being sleeved on the pin rod 315 and hinged with the first piston 311; a bottom end of the connecting rod 440 is hinged with the crank handle 430. The drive assembly 400 drives, via the crank handle 430 and the connecting rod 440, the first piston 311 to move back and forth between the vent position and the compressed position.

[0031] Referring to Fig. 2, a plurality of first through holes 316 distributed at intervals and flush with each other are provided at the lower end of the cylinder housing 312 of the first cylinder 310. Referring to Fig. 8, a plurality of second through holes 327 distributed at intervals and flush with each other are provided at the lower end of the cylinder barrel 322, and an elastic valve sleeve 360 configured to expose and cover the second through holes 327 is provided at the lower end of the cylinder barrel 322.

[0032] In a normal state, the crank handle 430 and the connecting rod 440 of the drive assembly 400 are in an aligned state, as illustrated in Fig. 11, where the first piston 311 is disposed at the vent position; now, the top surface of the first piston 311 is lower than the first through holes 316; the inside of the first cylinder 310 communicates with external air via the first through holes 316; the stepped portion 541 of the sliding block 540 abuts against an inner top wall of the locking groove 531 to limit the second piston 321 to the initial position.

[0033] During this process in which the drive assembly 400 drives, via the crank handle 430 and the connecting rod 440, the first piston 311 to move upward from the vent position, when the first sealing ring 314 is higher than the first through holes 316, the inside of the first cylinder 310 is isolated from the external air; during the process of the first piston 311 continuing upward movement, the first piston 311 compresses the air in the first cylinder 310, whereby the air pressure in the first cylinder 310 increases.

[0034] When the crank handle 430 and the connecting rod 440 move so that they are vertically aligned, the first piston 311 reaches the compressed position; now, the fist bevel 581 of the ejector pin 580 is fitted with the second bevel 543 of the sliding block 540 so that the sliding block 540 slides to migrate out of the locking groove 531, whereby the second piston 321 is released; the compressed air in the first cylinder 310 directly flows through the vent holes 323 into the second cylinder 320 to act on the top surface of the second piston 321, a fraction of the compressed air flowing into the grooved structure to act on the top surface of the second piston 321 via the shock-absorbing cushion 340; the released second piston 321 drives, under the pressure of the compressed air, the striker 330 to move downward. During a process of downward movement of the second piston 321 and the striker 330, the striker 330 contacts a nail fed by the nail feeder 200 to exert a force against the nail, driving the nail out of the nail feeder 200 into an object such as wood, whereby a nail driving action is completed.

[0035] When the second piston 321 moves downward to abut against the head plug 324, the second piston 321 and the striker 330 move downward till the nail-striking position; now, a nail driving action is completed; the top surface of the second piston 321 is lower than the second through hole 327; due to a larger air pressure in the second cylinder 320, the air pressure difference drives the elastic valve sleeve 360 to expose the second through hole 327, so that the high pressure air in the second cylinder 320 may be discharged out via the second through hole 327. When the air pressure is balanced between the inside of the second cylinder 320 and the external air, the elastic valve sleeve 360 covers the second through hole 327 so that the inside of the second cylinder 320 is isolated from the external air.

[0036] During the process in which the drive assembly 400 drives, via the crank handle 430 and the connecting rod 440, the first piston 311 to move downward from the compressed position to reset to the vent position, the air pressures in the first cylinder 310 and the second cylinder 320 drop; under the action of negative pressure, the second piston 321 moves upward from the nail-striking position to reset to the initial position. When the second piston 321 moves upward till being about to reach the initial position, the upper portion of the lock core 530 is inserted in the locking bush 520, with the conical surface of the top end of the lock core 530 abutting against the stepped portion 541 of the sliding block 540, driving the sliding block 540 to first overcome the elastic force of the locking spring 570 to slide a certain distance in a direction away from the lock core 530. When the second piston 321 drives the lock core 530 to move upward till its initial position, the stepped portion 541 is aligned with the locking groove 531; under the action of the elastic force of the locking spring 570, the sliding block 540 slides towards the lock core 530, driving the stepped portion 541 to be inserted in the locking groove 531 to abut against the inner top wall of the locking groove 531, whereby the second piston 321 and the striker 330 are limited to the initial position.

[0037] Upon nail driving, since the compressed air in the first cylinder 310 directly flows through the vent hole 323 into the second cylinder 320 to act on the second piston 321, there eliminates a need of setting a passage structure for the compressed air to flow through on the fixed base 510 and the locking bush 520, which lowers requirements on the airtight structure on the fixed base 510 to an appropriate extent, thereby lowering structural difficulty and airtight requirements of concerned members.

[0038] Other structures of the pneumatic nail gun according to this implementation may refer to the patents CN109623736A and US11478912B2, which will not be detailed here.

[0039] It may be understood that, the pneumatic nail gun according to this implementation may be powered by a battery pack or by mains electricity via a wire.Second Implementation

[0040] Referring to Fig. 12, in this implementation, the narrowed opening portion 322a is canceled from the cylinder barrel 322 so that the cylinder barrel 322 is directly formed as a tubular shape, which facilitates forming of the cylinder barrel 322. The lower end of the locking bush 520 is directly inserted in the top end of the cylinder barrel 322.

[0041] The remaining structures of the second implementation refer to the first implementation, which are not detailed here.Third Implementation

[0042] Referring to Fig. 13, in this implementation, setting of the elastic pad 560 is canceled. The sliding groove 511 is closed by a groove cover 592 that is disposed on top of the cover piece 591. To realize airtightness at the top side of the fixed base 510, an elastic sealing rib 593 is arranged between a circumferential exterior wall of the groove cover 592 and a circumferential interior wall of the sliding groove 511, the sealing rib 593 implementing circumferential seal-fitting between the groove cover 592 and the sliding groove 511. In addition, an airtight ring 594 is arranged between the nut 550 and the locking bush 520 and at a fitting interface between the fixed base 510 and the bolt, respectively, the airtight ring 594 being tightly pressed between the top surface of the fixed base 510 and the top wall of the cylinder housing 312. The sealing rib 593 and the airtight ring 594 implement airtightness at the top side of the fixed base 510, which prevents leakage of the compressed air from the assembly interstice of the locking assembly, thereby preventing pressure drop of the compressed air.

[0043] The remaining structures of the third implementation refer to the first implementation, which are not detailed here.

[0044] It may be understood that, the sealing rib 593 and the airtight ring 594 may adopt a sealing ring.

[0045] It may be understood that, the third implementation may be combined with the second implementation.Fourth Implementation

[0046] In this implementation, a bottom side of the sliding groove 511 is open, while a top side thereof is closed; the sliding block 540 is disposed in the sliding groove 511 via the metallic cover piece 591, the cover piece 591 being fixed together with the fixed base 510 via a screw, which prevents grooving on the top surface of the fixed base 510 and simplifies the airtight structure of the locking assembly 500. Specifically, the cover piece 591 is provided with a lug protruding outward, a hole is provided on the lug, and the fixed base 510 is provided with a screw hole that is a blind hole; the lug abuts against the bottom surface of the fixed base 510, so that the screw for securing the cover piece 591 passes through the hole on the lug and is screwed tightly in the screw hole on the fixed base.

[0047] The remaining structures of the fourth implementation refer to the first implementation, which are not detailed here.

[0048] It may be understood that, in this implementation, the top surface of the fixed base 510 may realize airtightness via the elastic pad 560 in the first implementation or the airtight ring 594 in the third implementation.

[0049] It may be understood that, the fourth implementation may be combined with the second implementation.

[0050] In addition to the example implementations described supra, the present disclosure also has other implementations; those skilled in the art may make various changes and modifications according to the present disclosure, and such changes and modifications shall all fall within the scope limited in the appended claims without departing from the spirit of the present disclosure.

Claims

1. A pneumatic nail gun, comprising a gun body and a nail feeder, inside the gun body being provided a cylinder assembly, a drive assembly and a locking assembly, the cylinder assembly comprising a first cylinder provided with a first piston, a second cylinder provided with a second piston, and a striker driven by the second piston, the first piston being driven by the drive assembly and having a vent position and a compressed position, the second cylinder being provided in the first cylinder and passing through the first piston, the second cylinder comprising a cylinder barrel, the second piston being disposed in the cylinder barrel, the second piston and the striker having an initial position and a nail-striking position, the locking assembly limiting the second piston to the initial position during a process of the first piston moving from the vent position to the compressed position, wherein the cylinder barrel has a vent hole providing communication between an inside of the first cylinder and an inside of the second cylinder, the vent hole being at least locally higher than a top surface of the second piston at the initial position, allowing for compressed air in the first cylinder to flow through the vent hole into the second cylinder to act on the second cylinder so that the second piston drives the striker to move from the initial position to the nail-striking position.

2. The pneumatic nail gun according to claim 1, wherein at least 50% of an area of the vent hole is set higher than the top surface of the second piston at the initial position.

3. The pneumatic nail gun according to claim 1, wherein an entirety of the vent hole is set higher than the top surface of the second piston at the initial position.

4. The pneumatic nail gun according to claim 1, wherein a plurality of vent holes are provided at intervals along a circumferential direction of the cylinder barrel; and / or, the vent holes are shaped into at least one of round holes, square holes, rectangular holes, elliptical holes, arc-shaped holes, and triangular holes.

5. The pneumatic nail gun according to claim 1, wherein a sealing ring axially positioned is sleeved circumferentially on the second piston, and the vent hole is set higher than the sealing ring at the initial position.

6. The pneumatic nail gun according to claim 1, wherein a shock-absorbing cushion is provided on the top surface of the second piston, the shock-absorbing cushion being provided with a grooved structure configurable for the compressed air to flow through.

7. The pneumatic nail gun according to claim 6, wherein an outside diameter of the shock-absorbing cushion is smaller than that of the second piston; and / or, the vent hole is set locally higher than a top surface of the shock-absorbing cushion at the initial position.

8. The pneumatic nail gun according to claim 6, wherein the grooved structure comprises a plurality of radial grooves distributed at intervals in a circumferential direction and a plurality of circumferential grooves providing communication between the radial grooves.

9. The pneumatic nail gun according to claim 1, wherein the locking assembly comprises a fixed base disposed in the first cylinder, a locking bush disposed on top of the cylinder barrel and inserted in the fixed base, a lock core disposed on the second piston and insertable in the locking bush, and a sliding block slidably disposed on the fixed base and fitted with the lock core to limit the second piston to the initial position, a sealing grease being filled in a fitting interstice between the locking bush and the fixed base.

10. The pneumatic nail gun according to claim 9, wherein the fixed base is provided with a sliding groove in which the sliding block is mounted, a top side of the sliding groove being open, the sliding block being mounted in the sliding groove via a cover piece, an elastic pad being arranged between a top portion of the fixed base and a top wall of the first cylinder; or, the fixed base is provided with a sliding groove in which the sliding block is mounted and a groove cover configured to cover the sliding groove, a top side of the sliding groove being open, the sliding block being mounted in the sliding groove via a cover piece, the groove cover being configured to cover the top side of the sliding groove, an elastic sealing rib being arranged between a circumferential exterior wall of the groove cover and a circumferential interior wall of the sliding groove; or, the fixed base is provided with a sliding groove in which the sliding block is mounted, a bottom side of the sliding groove being open, the sliding block being mounted in the sliding groove via a cover piece, the cover piece being fixed together with the fixed base.

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