Patent Application
20050235782
1. Field of the Invention
The present invention relates to a ratchet wrench, and more particularly to a ratchet wrench having an exact limit effect.
2. Description of the Related Art
In general, a conventional ratchet wrench comprises a handle, a drive head mounted on a distal end of the handle and having a first end formed with a receiving hole, a mediate portion formed with a receiving recess communicating with the receiving hole, and a second end formed with a receiving chamber communicating with the receiving recess, a ratchet wheel mounted in the receiving hole of the drive head, a pawl member pivotally mounted in the receiving recess of the drive head and engaged with the ratchet wheel, and a control knob rotatably mounted in the receiving chamber of the drive head and rested on the pawl member to push the pawl member to press the ratchet wheel to control the drive direction of the ratchet wheel. Thus, by control of the control knob, the ratchet wheel is rotated in one direction only when the drive head is rotated.
However, the control knob is not easily positioned in the receiving chamber of the drive head rigidly and stably, thereby causing inconvenience to a user when operating the control knob. In addition, the conventional ratchet wrench has a complicated construction, thereby greatly increasing the costs of fabrication.
The present invention is to mitigate and/or obviate the disadvantage of the conventional ratchet wrench.
The primary objective of the present invention is to provide a ratchet wrench having an exact limit effect.
Another objective of the present invention is to provide a ratchet wrench that only needs to provide a limit spring to position the control knob rigidly and stably, so that the ratchet wrench has a simplified construction, thereby decreasing costs of fabrication.
A further objective of the present invention is to provide a ratchet wrench, wherein the urging spring is supported and guided by the guide shaft of the positioning plate, so that the positioning plate is not easily deformed, thereby facilitating movement of the urging spring.
A further objective of the present invention is to provide a ratchet wrench, wherein the positioning plate is urged on the positioning edge of the pawl member rigidly and stably so as to position the pawl member exactly.
A further objective of the present invention is to provide a ratchet wrench, wherein the control knob is rigidly and stably positioned in the receiving chamber of the drive head by the limit spring, thereby facilitating a user operating the control knob.
In accordance with the present invention, there is provided a ratchet wrench, comprising:
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
Referring to the drawings and initially to
The ratchet wheel 20 is a substantially T-shaped socket. The ratchet wheel 20 has a periphery formed with a plurality of ratchet teeth 21 and has a bottom formed with an annular groove 22 for fixing a C-shaped snap ring 23 which is rested on a bottom of the drive head 11 to secure the ratchet wheel 20 on the drive head 11.
The pawl member 25 has a first side formed with a plurality of engaging teeth 26 engaged with the ratchet teeth 21 of the ratchet wheel 20 and a second side formed with an arcuate positioning edge 27.
The control knob 31 has an inside formed with a passage 32 radially extended through the control knob 31 and aligned with the positioning edge 27 of the pawl member 25 and has a periphery formed with an annular snap groove 34. Preferably, the snap groove 34 of the control knob 31 is located under and communicated with the passage 32. The control knob 31 has a first end formed with a drive handle 30 protruding outward from the drive head 11 and a second end formed with an enlarged resting plate 33 located adjacent to the snap groove 34 and rested on the limit spring 35.
A substantially C-shaped limit spring 35 is mounted in the snap groove 34 of the control knob 31 to rotate with the control knob 31 and has a mediate portion formed with a substantially U-shaped insertion portion 36 inserted into the passage 32 of the control knob 31 and two distal ends each formed with an arc-shaped protruding locking portion 37. The locking portion 37 of the limit spring 35 is bent outward and is movable with the limit spring 35 to abut a connection 18 of the receiving recess 13 and the receiving chamber 14 of the drive head 11 as shown in
A substantially E-shaped positioning plate 40 is mounted in the passage 32 of the control knob 31 and has a first end rested on the positioning edge 27 of the pawl member 25, and an urging spring 45 is mounted in a second end of the positioning plate 40 and urged between the positioning plate 40 and the drive head 11, so that the positioning plate 40 is urged on the positioning edge 27 of the pawl member 25 rigidly and stably as shown in
In operation, referring to
At the same time, when the control knob 31 is rotated, the limit spring 35 is also rotated. Thus, the locking portion 37 of one of the two distal ends of the limit spring 35 is moved to abut the connection 18 of the receiving recess 13 and the receiving chamber 14 of the drive head 11, and the locking portion 37 of the other one of the two distal ends of the limit spring 35 is moved to press an inner edge of the receiving chamber 14 of the drive head 11 as shown in
Accordingly, the ratchet wrench only needs to provide a limit spring 35 to position the control knob 31 rigidly and stably, so that the ratchet wrench has a simplified construction, thereby decreasing costs of fabrication. In addition, the urging spring 45 is supported and guided by the guide shaft 42 of the positioning plate 40, so that the positioning plate 40 is not easily deformed, thereby facilitating movement of the urging spring 45. Further, the positioning plate 40 is urged on the positioning edge 27 of the pawl member 25 rigidly and stably so as to position the pawl member 25 exactly. Further, the control knob 31 is rigidly and stably positioned in the receiving chamber 14 of the drive head 11 by the limit spring 35, thereby facilitating a user operating the control knob 31.
Referring to
Referring to
Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the true scope of the invention.
