CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serial no. 201811542453.1, filed on Dec. 17, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

FIELD

Embodiments of the present disclosure relate to the field of power tools, and more particularly relate to a nail gun which fires nails stably.

BACKGROUND

A nail gun is a type of tool capable of rapidly driving nails into wood or some other kind of material, which is commonly used in carpentry. Among all, air-powered nail guns are of a common type. A conventional air-powered nail gun is generally connected, via a hose, to an external compressed air source with a certain pressure, which external compressed air source provides power to push a striker to move. That is to say, conventional air-powered nail guns require cooperation from an additional set of high-pressure air source generating equipment such as an air compressor, posing much inconvenience to use.

Currently, there has been provided a nail gun which may address that issue well, wherein a large cylinder and a small cylinder are provided and firing is done utilizing an impact brought by a pressure difference generated from the volume difference between the large and small cylinders. However, that nail gun still has some problems. For example, a magnet locking structure is utilized to retain the small piston in the small cylinder at a high level; when the small cylinder is subjected to enough high compressed air pressure, the small piston is relieved from locking to strike a nail via a striker. Although a nail gun of that structure offers a more convenience to use, magnetic field force discrepancy inherent in a magnet and manufacturing tolerances of relevant fittings would cause retention force discrepancy in the small piston, a consequence of which is that the impact force of each nail gun might vary, while the varying impact force would further cause an unstable pressure difference, which in turn causes an unstable nail firing.

SUMMARY

An object of the present disclosure is to provide a nail gun which fires nails stably.

To achieve the object above, the present disclosure provides the following technical solution: a nail gun which fires nails stably, including: a housing, a trigger, an electric motor, a first cylinder, a second cylinder, a crank, a linkage, a nail firing assembly, and a nail supplying assembly, the second cylinder being disposed in the first cylinder, inside the first cylinder being provided a first piston, inside the second cylinder being provided a second piston, the linkage being in transmission connection with the first piston, the electric motor being in transmission connection with the crank via a transmission mechanism and driving, via the linkage, the first piston to make an axial motion in the first cylinder, a circulating air channel being provided between the first cylinder and the second cylinder, the nail firing assembly including a striker which is connected with the second piston, wherein an upper end inside the first cylinder is provided with a lock catch assembly locking the second piston to a high point, an unlocking ejector pin is provided on the first piston, the first piston moves upwards to drive the unlocking ejector pin to move upwardly, such that the unlocking ejector pin pushes the lock catch assembly to be detached from the second piston, and then the second piston moves downwardly under an air pressure to cause the striker to strike the nail.

Further, the second piston includes a piston core and a piston bush sleeved on the piston core, an upper end of the piston core is provided with a bayonet fitted with the lock catch assembly.

Further, the upper end inside the first cylinder is provided with a mounting seat, and inside the mounting seat is provided a mounting slot, wherein the lock catch assembly is installed in the mounting slot; a notch for the unlocking ejector pin to extend into is provided at a bottom portion of the mounting seat, and the unlocking ejector pin penetrates through the notch to act in cooperation with the lock catch assembly.

Further, the lock catch assembly includes a lock catch and a lock catch elastic element which pushes the lock catch to reset, a limiting step fitted with the bayonet and an open slot in communication with the notch are provided on the lock catch, and a push bevel fitted with the unlocking ejector pin is provided at an inner side wall of a lower end of the open slot.

Further, a mounting hole is provided inside a rear end of the lock catch, wherein one end of the lock catch elastic element is mounted in the mounting hole, and the other end thereof abuts against an inner wall of the mounting seat.

Further, a guide rail is provided in the mounting slot, wherein a profile of the guide rail is arranged to match that of the mounting slot; the guide rail is provided with a slideway, wherein the lock catch assembly is disposed in the slideway; and a bottom wall of the guide rail is provided with a through port in communication with the notch.

Further, an upper end of the piston core projects out of a top wall of the second cylinder; a guide bush is provided between the upper end of the piston core and the top wall of the second cylinder; an upper end of the guide bush penetrates through the mounting seat and a top wall of the first cylinder; and an upper end periphery of the guide bush is provided with an external thread and is fixed, via a nut, onto a top wall of the first cylinder.

Further, an upper end side wall of the guide bush is provided with a side opening for the lock catch assembly to penetrate through so as to act in cooperation with the bayonet.

Further, a lower end of the guide bush is provided with an annular step fitted with a top wall inner surface of the second cylinder, wherein a first sealing ring is provided between the annular step and the top wall inner surface of the second cylinder.

Further, the nail gun includes a trigger switch; a trigger ejector pin which can trigger the trigger switch upon trigger-pulling is provided on the trigger; the transmission mechanism includes a decelerator, a transmission shaft in transmission connection with the decelerator, and a cam sleeved on the transmission shaft; and a self-lock ejector pin is provided between the cam and the trigger switch, such that when the cam moves to the high point, it pushes the self-lock ejector pin to trigger the trigger switch and detach the trigger ejector pin from the trigger switch; while when the cam moves to a low point, the self-lock ejector pin is detached from the trigger switch.

Further, the trigger is provided with a rotary shaft, and the trigger ejector pin is provided with a rotary hole, such that the trigger ejector pin is sleeved, via the rotary hole, on the rotary shaft so as to cause the trigger ejector pin to motion with the trigger to trigger the trigger switch.

Further, a torsional spring causing the trigger ejector pin to deflect is further sleeved on the rotary shaft; a snap groove is provided on the trigger ejector pin; one end of the torsional spring is clamped in the snap groove of the trigger ejector pin, and the other end thereof abuts against a stop of the trigger.

Further, a bump is provided on the cam, such that when the cam moves to the high point, the bump contact-actuates a lower end of the trigger ejector pin to cause the trigger ejector pin to be deflected and detached from the trigger switch.

Further, the lower end of the trigger ejector pin is provided with a guide bevel which facilitates the bump to contact-actuate the trigger ejector pin.

Further, the bump is disposed at one side of the cam proximal to the decelerator, the bump and the cam being of an integral structure.

Further, a lower end of the self-lock ejector pin is provided with a fitting portion fitted with the cam, the fitting portion having a big-end-down trapezoidal shape.

Further, the nail gun further includes an MCU (Microcontroller Unit) and a selector switch that may freely switch the nail gun between a single nail mode or a continuous nail mode, the selector switch being electrically connected to the MCU.

Further, the nail firing assembly further includes a fixed seat, a nail exit base plate and a nail exit cover plate, wherein a lower end of the nail firing assembly is provided with a muzzle; a gain gun further includes a safety ejector pin assembly provided at the fixed seat side, wherein the safety ejector pin assembly includes a safety switch and a safety ejector pin; the nail supplying assembly includes a guide rail plate, a movable guide rail fitted with the guide rail plate, a nail supplying block which presses against the nail, and a nail supplying elastic element for resetting the nail supplying block being provided between the movable guide rail and the nail supplying block; on the nail exit base plate is provided a dry fire proof ejector pin; on the nail exit base plate is further provided a pin shaft penetrating through the dry file proof ejector pin; between the dry fire proof ejector pin and the nail supplying elastic element is provided an ejector block; when there exist no nails inside the nail supplying assembly, the nail supplying elastic element may presses against the ejector block, such that the ejector block presses against the dry fire proof ejector pin to axially limit the safety ejector pin to thereby prevent the safety ejector pin from contact-actuating the safety switch.

Further, on the movable guide rail is provided an accommodation groove for mounting the nail supplying elastic element; a front end of the nail supplying elastic element is provided with an elastic element ejector block; the elastic element ejector block is disposed within the accommodation groove; the ejector block is movably disposed in the accommodation groove and provided at a front end of the elastic element ejector block; a front end of the accommodation groove is provided with a limiting pin for limiting the ejector block; the ejector block includes a body, and a first push portion and a second push portion which are arranged in stagger, wherein the first push portion acts in cooperation with the dry fire proof ejector pin, and the second push portion acts in cooperation with the elastic element ejector block.

Further, the safety ejector pin assembly further includes: a bushing support fixed on the fixed seat, a movable inner tube movably provided in the bushing support, and a connecting rod in connection with the movable inner tube; wherein the connecting rod is connected to the safety ejector pin; an upper end of the movable inner tube is provided with a contact-actuating frame that triggers the safety switch and moves along with the movable inner tube; the safety ejector pin may move continuously along an axial direction of the movable inner tube so as to adjust an axial distance between a bottom end of the safety ejector pin and the muzzle.

In the present disclosure, the feature “when the cam moves to a high point” means the first/second piston moves to an upper limit position, and the feature “when the cam moves to a low point” means that the first/second piston moves to a lower limit position.

After adopting the technical solution above, the present disclosure has the following advantages:

1. In the present disclosure, by providing, at an upper end in the first cylinder, a lock catch assembly which locks the second piston to a high point, and by providing an unlocking ejector pin on the first piston, upward movement of the first piston drives the unlocking ejector pin to move upwardly; the unlocking ejector pin pushes the lock catch assembly to be detached from the second piston; under air pressure, the second piston moves downwardly to cause the striker to strike the nail. With the mechanical lock catch structure, pressure is maintained against locking of the second piston, which is more reliable and stable compared with a conventional magnetic locking manner with magnetic elements, such that individual discrepancies among magnetic elements would not cause instability or nonuniform of magnetic forces; the unstable or nonuniform magnetic forces would further cause nail firing under insufficient pressure against the second piston, which would affect the final nailing effect. In other words, the manner of locking and pressurizing the second piston by the lock catch assembly may well guarantee a nailing effect; the unstable factors inherent in the parts would not affect the nailing effect, such that nailing stability and nailing effect of the nail gun are guaranteed. Meanwhile, the lock catch assembly offers a reliable locking and an ease of detaching from the second piston. Further, the lock catch assembly has a simple structure such that it is easily manufactured.

2. The second piston includes a piston core and a piston bush sleeved on the piston core; an upper end of the piston core is provided with a bayonet fitted with the lock catch assembly; the bayonet on the piston core is fitted with the lock catch assembly to maintain pressure against locking to the second piston; in this way, it is convenient for the lock catch assembly to lock the second piston, and when the second piston is released, it is easy to be detached from the lock catch assembly, thereby guaranteeing nailing effect and nailing stability.

3. A mounting seat is provided at the upper end inside the first cylinder; a mounting slot is provided inside the mounting seat; the lock catch assembly is mounted in the mounting slot; a notch for the unlocking ejector pin to extend into is provided at a bottom portion of the mounting seat; and the unlocking ejector pin penetrates through the notch to act in cooperation with the lock catch assembly. The mounting seat and the mounting slot not only facilitate mounting and fixing the lock catch assembly, but also facilitate the unlocking ejector pin to contact-actuate the lock catch assembly when the first piston moves to the high point, thereby guaranteeing that the second piston may be well released and further guaranteeing a no-delay, accurate, and efficient nailing.

4. The lock catch assembly includes a lock catch and a lock catch elastic element configured for pushing the lock catch to reset; on the lock catch are provided a limiting step fitted with the bayonet and an open slot in communication with the notch; a pushing bevel fitted with the unlocking ejector pin is provided at an inner sidewall of the lower end of the open slot. The lock catch elastic element enables the lock catch, after being detached from the second piston, to be reset to the initial position; after the second piston is reset, it is locked by the lock catch again, ready for a next nailing action. In this way, working continuity of the nail gun is guaranteed, and working efficiency of the nail gun is enhanced. Meanwhile, when the second piston is locked by the lock catch, the elastic force of the lock catch elastic element may well guarantee the locking force with respect to the second piston, i.e., guaranteeing that the second piston is not easily loosened, wherein only under enough pressure force and under contact actuation from the unlocking ejector pin, can the second piston be detached. Moreover, arrangement of the open slot and the pushing bevel facilitates the unlocking ejector pin to contact-actuate the lock catch so as to guarantee that the lock catch can be accurately detached from the second piston to thereby release the second piston to perform nail shooting.

5. A mounting hole is provided inside the rear end of the lock catch; one end of the lock catch elastic element is mounted in the mounting hole, while the other end thereof abuts against the inner wall of the mounting seat; arrangement of the mounting hole facilitates limiting the lock catch elastic element to prevent the lock catch elastic element from being deflected from a radial direction, thereby guaranteeing working reliability of the lock catch elastic element, i.e., enabling the lock catch elastic element to push the lock catch stably and reliably.

6. A guide rail is provided in the mounting slot, wherein a profile of the guide rail is arranged to match a profile of the mounting slot; the guide rail is provided with a slideway, wherein the lock catch assembly is disposed in the slideway; and a bottom wall of the guide rail is provided with a through port in communication with the notch. As such, the friction between the lock catch and the mounting slot and the friction between the lock catch elastic element and the mounting slot may be reduced; besides, motion of the lock catch and the lock catch elastic element may be well guided to guarantee the overall working reliability and stability of the lock catch assembly.

7. An upper end of the piston core projects out of a top wall of the second cylinder; a guide bush is provided between the upper end of the piston core and the top wall of the second cylinder; an upper end of the guide bush penetrates through the mounting seat and the top wall of the first cylinder; and an upper end periphery of the guide bush is provided with an external thread and is fixed, via a nut, onto the top wall of the first cylinder. Arrangement of the guide bush facilitates fixing the second cylinder and the mounting seat and meanwhile facilitates communication between the second cylinder and the first cylinder to guarantee enough pressure against the second piston, thereby guaranteeing nailing stability and nailing effect.

8. An upper end side wall of the guide bush is provided with a side opening for the lock catch assembly to penetrate through so as to act in cooperation with the bayonet, which facilitates connection between the lock catch assembly and the piston core; moreover, the connection is reliable and stable; further, structural design becomes easier.

9. A lower end of the guide bush is provided with an annular step fitted with a top wall inner surface of the second cylinder, wherein a first sealing ring is provided between the annular step and the top wall inner surface of the second cylinder, which enhances sealing at the joint between the guide bush and the second cylinder and guarantees no air leakage, thereby guaranteeing enough pressure force against the second piston, guaranteeing enough striking force from the striker, and further guaranteeing the nailing effect.

10. The nail gun is provided with a trigger switch, and a trigger ejector pin is arranged on the trigger. After the trigger is pulled, the trigger switch may be triggered; then, the electric motor is energized to rotate to drive, via the transmission mechanism, the crank to motion, and then drives, via the linkage, the first piston to move axially in the first cylinder. A circulating air channel is provided between the first cylinder and the second cylinder. The first piston motions to compress the air in the first cylinder; the compressed air is conveyed to the second cylinder via the circulating air channel. As the compressed air applies enough air pressure against the second piston; the second piston is released and rapidly moves downwardly under this air pressure to cause the striker to strike the nail. The transmission mechanism specifically includes a decelerator, a transmission shaft in transmission connection with the decelerator, and a cam sleeved on the transmission shaft. A self-lock ejector pin is provided between the cam and the trigger switch, such that when the cam moves to a high point, it pushes the self-lock ejector pin to trigger the trigger switch and drives the trigger ejector pin to be detached from the trigger switch. That is, the self-lock ejector pin presses against the trigger switch to ensure that the trigger switch is not open, thereby guaranteeing continuous motion of the electric motor, which further ensures that the nailing process is not interrupted. The cam continues moving, and when the cam moves to a low point, the self-lock ejector pin is detached from the trigger switch, then the trigger switch is open to interrupt the power supply of the electric motor, and then the electric motor stops working, thereby finishing one action cycle of the nail gun. This manner of controlling the electric motor to finish an action cycle with a mechanical structure is more stable and reliable compared with conventional controlling through detection by a position sensor, thereby ensuring nailing reliability, i.e., guaranteeing working reliability of the nail gun.

11. A rotary shaft is provided on the trigger, a rotary hole is provided on the trigger ejector pin, and the trigger ejector pin is sleeved on the rotary shaft via the rotary hole. As such, the trigger ejector pin may motion with the trigger to trigger the trigger switch. This structure is not only simple and reliable, but also offers stable working to ensure the reliability of triggering the triggering switch, thereby further ensuring operating reliability of the electric motor and nailing reliability of the nail gun.

12. On the rotary shaft is further sleeved a torsional spring which may deflect the trigger ejector pin; a snap groove is provided on the trigger ejector pin; one end of the torsional spring is clamped into the snap groove of the trigger ejector pin, while the other end thereof abuts against a stop block of the trigger. As such, the trigger ejector pin generates a certain torsional force via the torsional spring, which facilitate the trigger ejector pin to maintain a working state, i.e., maintaining a good trigger position state when it is needed to trigger the trigger switch, while maintaining a good detached position state when it is needed to detach from the trigger switch, thereby enhancing working reliability and stability of the trigger ejector pin, such that the trigger ejector pin would not be affected by other external forces.

13. A bump is provided on the cam, such that when the cam moves to the high point, the bump may contact-actuate the lower end of the trigger ejector pin to cause the trigger ejector pin to be deflected and detached from the trigger switch to open the trigger switch, thereby guaranteeing the reliability of the cam in contact-actuating the trigger ejector pin.

14. A guide bevel facilitating the bump to contact-actuate the trigger ejector pin is provided at a lower end of the trigger ejector pin, which may well guarantee the reliability of the cam in contact-actuating the trigger ejector pin, i.e., easily actuating the trigger ejector pin to be defected, thereby facilitating triggering or detaching from the trigger switch.

15. By providing the bump at one side of the cam proximal to the decelerator, it facilitates the bump to avoid the self-lock ejector pin. Namely, when the cam is rotating, it does not contact the self-lock ejector pin, which guarantees action reliability of the trigger ejector pin; besides, by arranging the bump and the cam into an integral structure, i.e., machining them integrally, it facilitates manufacturing and machining of the bump and the cam; besides, the integral structure offers a good strength, durability, and long service life.

16. A lower end of the self-lock ejector pin is provided with a fitting portion fitted with the cam, wherein the fitting portion has a big-end-down trapezoidal shape, which enhances a contact area of fitting between the self-lock ejector pin and the cam, thereby facilitating reliable fitting between the self-lock ejector pin and the cam; besides, the reliable fitting guarantees action reliability of the self-lock ejector pin.

17. The nail gun further includes an MCU (Microcontroller Unit) and a selector switch that enables the nail gun to switch freely between a single nail mode or a continuous nail mode, the selector switch being electrically connected to the MCU; in this way, the nail gun may switch freely between the single nail mode and the continuous nail mode so as to meet different work requirements, thereby enhancing working efficiency of the nail gun.

18. By providing a safety ejector pin assembly and a dry fire proof ejector pin cooperating with the safety ejector pin assembly to prevent dry fire of the nail gun, use safety of the nail gun is enhanced. The safety ejector pin assembly includes a selector switch and a safety ejector pin; the nail supplying assembly includes a guide rail plate, a movable guide rail fitted with the guide rail plate, and a nail supplying block which presses against the nail; between the movable guide rail and the nail supplying block is provided a nail supplying elastic element for resetting the nail supplying block; the dry fire proof ejector pin is hinged to the pin shaft of the nail exit base plate; and an ejector block is provided between the dry fire proof ejector pin and the nail supplying elastic element. As such, when there exist no nails inside the nail supplying assembly, the nail supplying elastic element may presses against the ejector block which then pushes against the dry fire proof ejector pin to axially limit the safety ejector pin in the axial direction to thereby prevent telescoping of the safety ejector pin from contact-actuating a safety switch. In this case, the nail gun cannot perform a nailing operation, thereby guaranteeing use safety of the nail gun when the nails run out.

19. An accommodation groove for mounting the nail supplying elastic element is provided on the movable guide rail; a front end of the nail supplying elastic element is provided with an elastic element ejector block, wherein the elastic element ejector block is disposed in the accommodation groove. By arranging the nail supplying elastic element in the accommodation groove and with the elastic element ejector block pressing tightly the nail supplying elastic element into the accommodation cavity, the nail supplying elastic element is enabled to constantly maintain a compressed elastic force, which enables the nail supplying elastic element to constantly press against the nail supplying block. The nail supplying block presses against a nail to deliver it; in this way, it may well guarantee that the direction of pushing the nail supplying elastic element is not deflected, thereby guaranteeing stability of nail supplying. Meanwhile, where there exist no nails, the nail supplying elastic element pushes against the ejector block via the elastic element ejector block, causing the dry fire proof ejector pin to axially limit the safety ejector pin, thereby preventing telescoping of the safety ejector pin from contact-actuating the safety switch. Besides, the elastic element ejector block is in fit contact with the ejector block; the large contact area of fitting facilitates pressing against the ejector pin, which guarantees that the ejector block imposes an enough pushing force against the dry fire proof ejector pin and further guarantees that the dry fire proof ejector pin imposes a reliable axial limitation to the safety ejector pin. Second, by movably disposing the ejector block in the accommodation groove and at the front end of the elastic element ejector block, and by providing, at the front end of the accommodation groove, a limiting pin for limiting the ejector pin, it facilitates limiting the ejector block to prevent the ejector block from escaping, thereby guaranteeing the reliability and stability of the ejector pin in pushing the dry fire proof ejector pin. Further, the ejector block includes a body, and a first pushing portion and a second pushing portion which are disposed at two ends of the body and arranged in stagger, wherein the first pushing portion acts to cooperate with the dry fire proof ejector pin, and the second pushing portion acts to cooperate with the elastic element ejector pin. The cross-section of the ejector block has a stepped shape, such that the first pushing portion and the second pushing portion may not only work independently without mutual interference, but also may form a good limitation and fixation to the ejector block.

20. A safety ejector pin assembly is provided, wherein the safety ejector pin assembly includes a safety switch, a bushing support fixed on the fixed seat, a movable inner tube movably disposed in the bushing support, a connecting rod in connection with the movable inner tube, and a safety ejector pin in connection with the connecting rod. At an upper end of the movable inner tube are provided a trigger safety switch and a contact-actuating frame which is movable along with the movable inner tube, such that when the nail gun performs nailing, the trigger can only be pulled when the safety ejector pin is pressed to energize the safety switch, and then the electric motor rotates to start nailing. In other words, without pressing against the safety ejector pin, the trigger cannot be pulled to drive the electric motor to rotate, i.e., the nail gun cannot be energized to work, which enhances use safety of the nail gun. Meanwhile, a nailing depth is affected by the distance between the muzzle and a wood board. Specifically, the closer the distance from the muzzle is, the deeper the nail is driven into the wood board; the farther the distance between the muzzle and the wood board is, the shallower the nail is driven into the wood board. By configuring the safety ejector pin to be continuously movable along the axial direction of the movable inner tube so as to adjust the axial distance between the bottom end of the safety ejector pin and the muzzle (wherein change of the axial distance refers to change of the distance between the muzzle and the wood board, and adjusting the movable inner tube to adjust the axial distance between the bottom end of the safety ejector pin and the muzzle refers to adjusting the distance between the muzzle and the wood board), nailing depth becomes adjustable to ensure the nailing effect. That is, the axial distance between the bottom end of the safety ejector pin and the muzzle may be adjusted based on depths of different wood boards, thereby guaranteeing a good nailing effect and further enhancing the adaptability of the nail gun, i.e., enabling the nail gun to nail wood boards of different depths.

