1. Field of the Invention
The present invention relates to a transmission mechanism for an electric nail gun, and more particularly to a transmission mechanism with a driving wheel driven by electricity disposed in a nail gun housing and a rack disposed in the nail gun housing and in mesh with the driving wheel, the driving wheel being configure for driving the rack to move downward linearly to hit a nail.
2. Description of Related Art
An electric nail gun is a type of tool used to drive nails into wood or some other kind of material. Usually, there is a battery pack or an AC electrical power source in a housing of the electric nail gun to provide electrical power to a motor, thereby rotating the motor. A rotary kinetic energy of the motor is transformed into a linear kinetic energy by a transmission mechanism to drive a hitting bar to hit a nail.
Among a more advanced technology, many US patents, such as U.S. Pat. No. 6,607,111 and U.S. Pat. No. 6,669,072 and so on, teach a flywheel driven by a DC motor, a clutch assembly being capable of moving linearly by traction of a wire disposed on an axis of a solenoid. The clutch assembly has a wire drum and connects to a driving stand of a nail hitting bar by at least a wire. When a nail gun is driven by a user, the clutch assembly is moved along an axis direction to mesh with a flywheel which is rotating, thereby rotating the clutch assembly. Therefore, a rotary kinetic energy is transformed into a linear kinetic energy of the hitting bar to then hit nails via traction of the wire. However, the structure of the clutch assembly is complicated with too many components. In addition, using a wire to pull the driving stand and the hitting bar may cause high temperature and wearing on the wire so that the durability and the lifetime of the wire are reduced. Hence, the above mentioned driving mechanism needs to be improved.
What is needed, therefore, is to provide a transmission mechanism for an electric nail gun, which uses a flywheel to rotate a driving wheel so as to drive a rack to further drive a hitting bar to move linearly downward and hit a nail, so as to simplify a wire drum and a clutch assembly and overcome the problem of reduced lifetime of a wire in a previous technology.
To achieve the above objective, preferred embodiments of the present invention provide a transmission mechanism for an electric nail gun including a linear transmission unit in a housing of the electric nail gun and a rotary transmission unit in the housing. The rotary transmission unit includes an electric driven driving wheel. The linear transmission unit includes a rack in mesh with the driving wheel and slidably installed in the housing by a spring force, and a hitting bar at a bottom of the linear transmission unit. The rack is configured to receive driving from the driving wheel and to drive the hitting bar to move linearly downward to hit a nail.
In addition, at least a guiding bar is vertically disposed on a side of the driving wheel, the rack is slidably installed on the guiding bar, and a first elastic member is disposed on the guiding bar and configured for pushing the rack to drive the hitting bar to move upward and reset when the driving wheel stops rotating. A slide base is disposed on a top of the rack holding the guiding bars and configured for guiding the rack to be slidably installed on the guiding bars. At least a turning wheel is pivotably disposed near to the driving wheel. The rack is disposed between the driving wheel and the turning wheel and in mesh with the driving wheel.
The rotary transmission unit of the present invention further includes a motor, a flywheel, and a solenoid. The motor is driven by electricity. The flywheel is driven by the motor and pivotably mounted on a stop shaft. The flywheel has a cylinder extending from a side of the flywheel. The cylinder is made of magnetic material and defines a ring-shaped receiving chamber therein. The solenoid can be activated by electricity and is buried in the receiving chamber, being configured for forming magnetic field around a magnetic loop on the cylinder. The driving wheel is movably and pivotably disposed between an engagement position near to an end of the cylinder and a disengagement position. At least two friction surfaces are respectively disposed near to the driving wheel and the cylinder therebetween. The friction surfaces are capable of working as a clutch.
By this means, when the solenoid is activated by electricity, the driving wheel is attracted to move to the engagement position to be driven by the flywheel, and thereby drives the linear transmission unit to hit a nail. When the solenoid is demagnetized the driving wheel is configured to be released and reset to the disengagement position to disengage from the flywheel, and thereby to stop driving the linear transmission unit.
In further embodiments, the rotary transmission unit further includes a second elastic member configured for exerting an pushing force on the driving wheel, and thereby pushing the driving wheel from the engagement position to the disengagement position. The pushing force is configured less than the force exerted by the magnetic field to attract the driving wheel to move. The second elastic member is disposed between a ring-shaped bearing securely mounted on a stop shaft and a ring-shaped traction stand moveably and pivotably attached to the stop shaft.
In yet further embodiments, the rotary transmission unit includes a second elastic member configured for exerting an pushing force on the driving wheel, thereby pushing the driving wheel from the engagement position to the disengagement position. The pushing force being configured less than the force with which the traction stand attracted by the magnetic field drives a push paw to push the driving wheel to move. The second elastic member is disposed in the cylinder between the flywheel and the driving wheel.
It is a novelty for employing magnetic field effect of the solenoid to control engagement or disengagement of the driving wheel in/from the flywheel so as to transmit rotary kinetic energy to drive the rack to move the hitting bar downward to hit a nail. The configuration space of the components is sufficiently saved. In addition, because two frictional surfaces are formed between the driving wheel and the cylinder which can be used as a clutch, the rotary kinetic energy of the flywheel is fully transmitted to the driving wheel. Furthermore, the rack is used as a following device in the linear transmission unit so that even when temperature is raised high after long time of operation, the wearing between the driving wheel and the rack can still be reduced. It also facilitates transformation of the rotary kinetic energy of the driving wheel into the linear kinetic energy of the rack, thereby improving the durability of the transmission mechanism for the electric nail gun in a space-saving fashion.
Other advantages and novel features will be drawn from the following detailed description of preferred embodiment with the attached drawings, in which:
a to
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a and
Referring to
In this embodiment, the linear transmission unit 4 has a rack 41 mounted by a spring in the nail gun 1 in mesh with the driving wheel 26. A hitting bar 42 is formed on the rack 41 so that the hitting bar 42 can hit a nail when the rotary kinetic energy of the driving wheel 26 is transformed into the linear kinetic energy of the rack 41 (shown in
More specifically, at least a guiding bar 40 is disposed at a side of the driving wheel 26. In this embodiment, two guiding bars 40 are respectively and vertically disposed in a vertical guiding grooves 111 and 121 of a supporting brackets 11, 12 respectively beside the driving wheel 26. The rack 41 is slidably disposed between the two guiding bars 40 to receive the driving of the driving wheel 26. A first elastic member 43 is disposed on the guiding bar 40. The pushing force exerted by the first elastic member 43 is smaller than the force exerted by the driving wheel 26 in rotation and is configured to push the rack 41 to drive the hitting bar 42 to move upward and reset (shown in
A slide base 44 is disposed on a top of the rack 41. Both sides of the slide base 44 are respectively disposed in the two guiding grooves 111 and 121 (shown in
The rotary transmission unit 2 includes a motor 21, a flywheel 22, a solenoid 24, and a driving wheel 26.
The motor 21, which is securely mounted on bottom ends of the supporting bracket 11, 12 can be driven by the battery pack 10 controlled via the first switch 16 or the second switch 17. Alternatively, the motor 21 may be driven by other AC (alternating current) power supplies via a conductive wire. A drive belt wheel 210 is disposed on an axis of the motor 21.
The configuration of the flywheel 22 is similar to the configuration of the belt wheel 210. The flywheel 22 is pivotably mounted on a stop shaft 13, which is fixedly mounted between a supporting arm 14 and the supporting bracket 12 to cause the flywheel 22 to locate above the motor 21. The supporting bracket 11 extends outwards to form the supporting arm 14 thereon. A belt 211 is wrapped around the drive belt wheel 210 and the flywheel 22 to cause rotation of the flywheel 22. In addition, an end side of the flywheel 22 extends outwards to form a cylinder 23, to thereby rotate together with the flywheel 22. Alternatively, the cylinder 23 may be fixedly attached to the flywheel 22. The cylinder 23 should be made of magnetic material regardless of attachment of the cylinder 23 to the flywheel 22. A ring-shaped receiving chamber 230 is defined in the cylinder 23.
The solenoid 24, which is buried in the receiving chamber 230 of the cylinder 23, does not rotate along with the flywheel 22 and the cylinder 23. In the first embodiment of the present invention, the solenoid 24 is wrapped around an insulative ring stand 240 and may be activated by current that is controlled by the first switch 16 or the second switch 17. Thus, a magnetic loop 241, as shown in
The driving wheel 26, adjacent to an end side of the cylinder 23, is pivotably disposed between an engagement position 26a (shown in
In addition, the present invention also includes a second elastic member 28 configured for exerting an pushing force on the driving wheel 26, thereby pushing the driving wheel 26 from the engagement position 26a (shown in
Furthermore, a stop block 262 is extended from the driving wheel 26, and a brake post 15 is transversely disposed between the two supporting brackets 11, 12. When the rotary kinetic energy of the flywheel 22 is transformed to the driving wheel 26 via the cylinder 23 and the clutch 5, the brake post 15 can limit an angle by which the driving wheel 26 rotates, and thereby control a linear displacement of the rack 41.
According to the above-mentioned configuration, when using the electric nail gun to nail a workpiece, a user must first push the safe sliding rod 18 against the workpiece to turn on the first switch 16 (shown in
Referring to
To sum up, the present invention has sufficiently taught necessary technical features which can be employed in industry. It is a novelty for employing magnetic field effect of the solenoid to control engagement or disengagement of the driving wheel in/from the flywheel so as to transmit rotary kinetic energy to drive the rack to move the hitting bar downward to hit a nail. A reasonable configuration for the flywheel, the solenoid, the clutch, and the driving wheel is space saving. The durability of the transmission mechanism for the electric nail gun is also improved.
The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the invention disclosed herein, including configurations ways of the recessed portions and materials and/or designs of the attaching structures. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.