Patent Application
20170282344
This application claims the priority of Taiwanese patent application No. 105204526, filed on Mar. 31, 2016, which is incorporated herewith by reference.
The present invention relates generally to an electric tool, and more particularly to an output-mode switching device for an electric tool such that the switching device can switch among a continuous rotation, rotation in a single direction and rotation and simultaneously providing an axial impact during the rotation.
A conventional electric tool, like an electric drill, includes a motor, wherein its power is transmitted to an output shaft via a gear system. In order to tightening and/or loosening a screw or a nut smoothly, some electric tools are provided with impact function such that a fully tightened nut can be swiftly loosened and/or a loosely-mounted nut can be swiftly tightened relative to the object.
A conventional output-mode switching device for an electric tool is disclosed. The switching device can switch among a continuous rotation, rotation in a single direction and rotation and providing an axial impact during the rotation. However, it is noted that the structure is relatively complicated due to too many components, thereby incurring high manufacturing expense. In addition, when said switching device is applied in an electric tool, like rotating in a specific direction and simultaneously providing impact function along the axial direct, and in the event that an operating bit rotating in the specific direction is forced to rotate in a direction opposite to the specific direction, the motor and/or other components of the electric tool may be damaged. The reasons reside in that no stop means is provided to prevent the operating bit to rotate in the opposite direction of the specific direction.
A primary objective of the present invention is to provide an output-mode switching device for an electric tool, which can eliminate the prior drawbacks, the complicated structure having too many components, thereby incurring high manufacturing expense. In the same time, when the switching device is applied in an electric tool, the operating bit can switch among a continuous rotation, rotation in a single direction and rotation and simultaneously providing an axial impact during the rotation. In the event that the operating bit rotating in the specific direction is forced to rotate in a direction opposite to the specific direction, the motor and/or other components of the electric tool are prevented from being damaged.
One distinct feature of the present invention resides in that an output shaft unit is disposed in an outer casing of an electric tool, which further includes a fixed ratchet unit, a torque unit and a function switch unit. The output shaft unit includes an output shaft and a movable ratchet wheel mounted in such a manner that the movable ratchet wheel is movable axially along the shaft and is non-rotatable with the shaft. The fixed ratchet unit includes a fixed ratchet wheel sleeved around the shaft and has ratchet teeth for meshing with movable ratchet teeth of the movable ratchet wheel. The function switch unit includes a switch ring mounted rotatably on the casing, wherein rotation of the switch ring about its axis results in rotation of pawls within the switch ring, thereby driving the pawls about its pivot points and meshing and/or non-meshing of the pawls with external ratchet teeth of the fixed ratchet wheel and switching the output shaft among a continuous rotation, rotation in a single direction and simultaneously providing an axial impact during the rotation.
An output-mode switching device for an electric tool includes: an outer casing, an output shaft unit, a fixed ratchet unit, a toque unit and a function switch unit. The outer casing defines an interior chamber. The output shaft unit is disposed in the interior chamber, includes an output shaft having a first shaft section and a movable ratchet wheel mounted on the first shaft section in such a manner that the movable ratchet wheel is movable axially along the output shaft and is non-rotatable with the output shaft. The movable ratchet wheel has a first end formed with circumferential ratchet teeth on its external surface thereof. The fixed ratchet unit includes a fixed ratchet wheel that is sleeved around the first shaft section and that has a second end formed with ratchet teeth for meshing with the ratchet teeth of the movable ratchet teeth and a restoration spring. The fixed ratchet wheel further has a plurality of external ratchet teeth formed on its outer surface. The restoration spring is being disposed between the movable ratchet wheel and the fixed ratchet wheel and has two opposite ends respectively abutting against the first end of the movable ratchet wheel and the second end of the fixed ratchet wheel. The toque unit includes a torque cover, an annular sleeve coupled with the torque cover, an annular cushion pad having a plurality of inner protrusions and a plurality of compression springs, the torque cover being mounted rotatably on the outer casing. The function switch unit includes a switch ring mounted rotatably on the outer casing behind the toque unit, a plurality of pawls and a plurality of torsion spring which are mounted pivotally within the switch ring so as to extend parallel with an axis of the switch ring such that rotation of the switch ring on the outer casing about its axis results in engagement of the inner protrusions of the annular cushion pad with the pawls, thereby driving the pawls about its pivot points and meshing and/or non-meshing of the pawls with the external ratchet teeth of the fixed ratchet wheel.
In the present embodiment, the output shaft is capable providing axial impact during rotating in a specific direction, the rotation of the output shaft in the specific direction provides high effective, since the output shaft is provided means from rotating in the direction opposite to the specific direction, thereby preventing damage done onto the motor or the other components. Each of The ratchet teeth formed on the second end and the external ratchet teeth formed on its outer surface of the fixed ratchet is asymmetric so is the ratchet teeth formed on the first end of the movable ratchet wheel for meshing and non-meshing with the ratchet teeth of the fixed ratchet wheel.
Preferably, each of the pawls has an abutment section for abutting against a respective one of the inner protrusions of the annular cushion pad, thereby driving the pawls during rotation of the annular cushion pad.
Preferably, the annular cushion pad has an inner wall surface from which the inner protrusions project radially and inwardly toward its axis thereof.
Compared with the prior output-mode switching device for an electric tool, the structure of the components of the present output-mode switching device is relatively simple, thereby lowering the manufacturing expense. In addition, since the output shaft is prevented from rotating in an opposite direction of a specific direction in which the output shaft is rotating, no damage can be done onto the motor and/or the other component of the switching device of the present invention.
The present invention will be apparent to those skilled in the art by reading the following detailed description of a preferred embodiment thereof, with reference to the attached drawings, in which:
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
It is to note that when referring a front end of an element, the other end opposite to the front end will be denoted as the second end. Every element will be described in the similar manner in order to better understanding of the present invention.
The present invention is to provide an output-mode switching device for an electric tool (like an electric drill) having an output shaft that can be switched among a continuous rotation, rotation in a single direction and rotation and simultaneously providing an axial impact during the rotation.
Referring to
The fixed ratchet unit 2 includes a fixed ratchet wheel 21, two annular first cushion pads 22, a restoration spring 23, two annular cushion pads 24, a bearing disk 25 and a first bearing unit 26, wherein the fixed ratchet wheel 21 has a through hole 210 sleeved around the first shaft section 111 the output shaft 11, a second end formed with ratchet teeth 212. In this embodiment, each of the ratchet teeth 212 is asymmetric as best shown in
After assembly, the first shaft section 111 of the output shaft 11 extends sequentially through the first bearing unit 112, the nut covering 113 and the movable ratchet wheel 114, and further through one first cushion pad 22, the restoration spring 23, another first cushion pads 22, the through hole in the fixed ratchet wheel 21, one second cushion pad 24, the bearing disk 25, another second cushion pad 24 and the second bearing unit 26 such that the two first cushion pads 22 respectively abut against the second end of the fixed ratchet wheel 21 and the first end of the movable ratchet wheel 114 while two opposite ends of the restoration spring 23 respectively abutting against the cushion pads 22. The second cushion pads 24 respectively abut against the first end of the fixed ratchet wheel 21 and the second end of the second bearing unit 26 while the bearing disk 25 abuts against the second cushion pads 24. The restoration spring 23 provides an axial compression force so as to space the movable ratchet wheel 114 and the fixed ratchet wheel 21 apart from each other on the output shaft 11.
Note that the previously mentioned output shaft unit 1 and the fixed ratchet unit 2 are disposed within the interior chamber of the outer casing 3 such that all the elements mentioned above also located within the interior chamber.
The toque unit 4 includes a torque cover 41, an annular sleeve 411 coupled with the torque cover 41, an annular cushion pad 412 having a plurality of inner protrusions 4121 and a plurality of compression springs 413, wherein the torque cover 41 has inner threads for rotatably fastened with outer threads of the outer casing 3 such that the torque cover 41 is rotable relative to the outer casing 3. The annular cushion pad 412 is coupled to a first end of the annular sleeve 411, after which the torque cover 41, the annular sleeve 411 and the annular cushion pad 412 are coupled to the outer casing 3 so that the second ends of the compression springs 413 are mounted on the first end of the annular cushion pad 412.
The function switch unit 5 includes a switch ring 51 mounted rotatably on the outer casing 3 behind the toque unit 4, two pawls 52 which are mounted pivotally to screw holes 5110 in two mounting posts 511 of the switch ring 51 via two fastener screws 53 such that pivot axes of the pawls 52 extend parallel with an axis of the switch ring 51. Each of two torsion springs 54 is sleeved around a respective mounting post 511 and has two opposite ends respectively abutting against the pawls and the switch ring 51. It is to note that due to biasing action of the torsion spring 54, the pawls 52 tend pivotally towards an axis of the switch ring 51. Note that each of the pawls 52 has an abutment section 522 such that after assembly one end of each torsion spring 54 abuts against the abutment section 522 such that the engaging ends 521 of the pawls 52 abut against respective inner protrusions 4121 of the annular cushion pad 412.
The toque unit 4 is used to adjust the torque of the output shaft 11. When the torque cover 41 is rotated in a normal direction (clockwise direction) and/or in an opposite direction (counterclockwise direction) with respect to the outer casing 3, the torque cover 41 is axially moved toward the first end and/or the second end. Movement of the torque cover 41 axially toward the first end results in pressing of the compression springs 413, thereby driving the output shaft 11 in a high torque speed and movement of the torque cover 41 axially toward the second end releases pressing off the compression springs 413, thereby driving the output shaft 11 in a low torque speed.
The function switch unit 5 is used to alter the modes of the output shaft 11. There are marks provided on the outer surface of the switch ring 51, as shown in
The switching modes of the output shaft will be described in the following paragraphs.
As shown in
Referring to
Referring to
Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 105204526 | Mar 2016 | TW | national |
