Patent Application
20170113332
1. Fields of the Invention
The present invention relates to a ratchet wrench, and more particularly, to a ratchet wrench using a smaller pawl to save manufacturing cost.
2. Descriptions of Related Art
The conventional ratchet wrench is disclosed in U.S. Pat. No. 7,444,903, and comprises a wrench body having an end portion provided with a mounting hole and a receiving chamber connected to the mounting hole. A ratchet wheel is mounted in the mounting hole of the wrench body and has an outer wall provided with a plurality of ratchet teeth. A pawl member defining a top surface and a bottom surface is mounted in the receiving chamber of the wrench body, and has a first side including a first end provided with a plurality of locking teeth extending from the top surface to the bottom surface so as to be engaged with the ratchet teeth of the ratchet wheel successively and completely. A second end of the pawl member is provided with a sliding face extending from the top surface to the bottom surface slidable on the ratchet teeth of the ratchet wheel. The first and second ends define a whole circumferential length of the first side of the pawl member. An elastic member is mounted in the receiving chamber of the wrench body and biased between a peripheral wall of the receiving chamber of the wrench body and a second side of the pawl member to push the pawl member toward the ratchet wheel. The elastic member is located adjacent to the sliding face of the pawl member and the sliding face of the pawl member is located between the elastic member and the locking teeth of the pawl member. The first side of the pawl member is a concave surface which extends through the whole circumferential length of the first side of the pawl member. The sliding face of the pawl member is a concave recessed smooth surface which extends successively and completely through a circumferential length of the second end of the first side of the pawl member that is half of the circumferential length of the first side of the pawl member. The pawl member is movable relative to the ratchet wheel between a first position where all of the locking teeth of the pawl member are engaged with the ratchet teeth of the ratchet wheel closely and completely, and the sliding face of the pawl member evades the ratchet teeth of the ratchet wheel, and a second position where all of the locking teeth of the pawl member are disengaged from the ratchet teeth of the ratchet wheel, and the sliding face of the pawl member is movable on the ratchet teeth of the ratchet wheel.
In order to prevent the elastic member from randomly moved within the receiving chamber, the pawl member has to be made to be big enough so as to restrict the room that the elastic member moves. However, the pawl member is now made by way of injection molding instead of powder metallurgy, and this means that the bigger size of the pawl member is made, the higher manufacturing cost is applied. Besides, because the pawl member is pushed by the elastic member along the direction that is shown by the arrowhead, this causes the right rear side of the pawl member not to firmly contact against the inside of the receiving chamber, so that the engagement between the pawl member and the ratchet wheel is not secured.
The present invention intends to provide a ratchet wrench to eliminate the shortcomings mentioned above.
The present invention relates to a ratchet wrench and comprises a head having a handle connected thereto, and the head has a first room defined therethrough. A second room is defined in the inner periphery of the first room. The center of the second room is located within the first room. The second room is located between a top closed portion and a bottom closed portion of the head. A first groove is defined in the inner periphery of the first room. A ratchet wheel is rotatably located in the first room and has multiple ratchet teeth defined in the outer periphery thereof. The ratchet teeth are located at the middle portion of the ratchet wheel. A mounting portion is defined axially in the ratchet wheel. A second groove is defined in the outer periphery of the ratchet wheel and located corresponding to the first groove. The ratchet wheel has a first outer surface and a second outer surface. The ratchet teeth are located between the first and second outer surfaces. A pawl is located in the second room and has multiple engaging teeth defined in the front side thereof. The engaging teeth are engaged with the ratchet teeth. A curved face is defined in the rear side of the pawl, and a recess is defined in the curved face. A protrusion extends from one end of the curved face. A resilient member has its first end received in the recess, and the second end of the resilient member contacting the inside of the second room. The resilient member biases the pawl to be engaged with the ratchet wheel. A clip is engaged with the first and second grooves to restrict the ratchet wheel in the first room. A pin has a middle section thereof located in the second room to restrict movement of the pawl in the second room.
The present invention will become more obvious from the following description when taken in connection with the accompanying drawings which show, for purposes of illustration only, a preferred embodiment in accordance with the present invention.
Referring to
A ratchet wheel 20 is rotatably located in the first room 11 and has multiple ratchet teeth 21 defined in the outer periphery thereof. The ratchet teeth 21 are located at the middle portion of the ratchet wheel 20. A polygonal mounting portion 22 is defined axially in the ratchet wheel 20 so as to be mounted to a polygonal object such as a nut or a screw. A second groove 23 is defined in the outer periphery of the ratchet wheel 20 and located corresponding to the first groove 13. The ratchet wheel 20 has a first outer surface 24 and a second outer surface 25. The ratchet teeth 21 are located between the first and second outer surfaces 24, 25. The diameter of the first outer surface 24 is the same as that of the second outer surface 25. The tips of the ratchet teeth 21 protrude beyond the first and second outer surfaces 24, 25.
A pawl 30 is located in the second room 12 and has multiple engaging teeth 31 defined in the front side thereof. The engaging teeth 31 are engaged with the ratchet teeth 21. A curved face 300 is defined in the rear side of the pawl 30. A recess 32 is defined in the curved face 300. A protrusion 33 extends from one end of the curved face 300, and a curved contact face 301 extends from another end of the curved face 300. The curved contact face 301 and the second room 12 have a same radius. A resilient member 40 has the first end thereof received in the recess 32, and the second end of the resilient member 40 contacts the inside of the second room 12. The resilient member 40 biases the pawl 30 to be engaged with the ratchet wheel 20. A C-shaped clip 50 is engaged with the first and second grooves 13, 23 to restrict the ratchet wheel 20 in the first room 11. A pin 60 extends through the positioning hole 14 and has its middle section thereof located in the second room 12 to restrict movement of the pawl 30 in the second room 12. The pin 60 includes a first end 61 and a second end 62, wherein the first end 61 extends through the first hole 141 and the second end 62 extends through the second hole 142. The first end 61 of the pin 60 has outer threads which are engaged with the inner threads of the first hole 141. The second end of the pin 60 has a circular cross section which extends through the second hole 142.
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The pin 60 extends through the positioning hole 14 and the middle section of the pin 60 is located in the second room 12 so as to restrict the movement of the pawl 30. Therefore, the pawl 30 can be made to be ½ volume of the second room 12 so that the manufacturing cost is reduced.
When the pawl 30 is separated from the ratchet wheel 20 and moves in the second room 12, the pawl 30 is stopped by the pin 60, the engaging teeth 31 are completely separated from the ratchet teeth 21. The size of the pawl 30 can be reduced.
The resilient member 40 is located in the recess 32 of the pawl 30 and biased between the rea side of the pawl 30 and the inside of the second room 12. The curved face 300 is easily pushed by the resilient member 40 at an angle to contacts against the inside of the second room 12, so that the engagement between the engaging teeth 31 and the ratchet teeth 21 is secured.
While we have shown and described the embodiment in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
