Patent Publication Number: US-2019176314-A1

Title: Power tool and its transmission shaft

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
     Not applicable. 
     REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a partial structure of a power tool, and more particularly to an innovative design of the oil filling structure of the transmission shaft of a power tool. 
     2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98 
     Due to the structural design of a transmission shaft, like one in a power tool, it is necessary to apply lubrication oil on the driving section of the transmission shaft as well as the corresponding position on the power tool hammer frame, so as to lubricate the hammering component and keep a long lifecycle of the power tool. Along with the continuous use of the power tool, the lubrication oil inside will lose gradually. Therefore, after a certain period of usage, the lubrication oil inside the power tool should be replenished. 
     Thus, to overcome the aforementioned problems of the prior art, it would be an advancement in the art to provide an improved structure that can significantly improve the efficacy. 
     Therefore, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention of “a power tool and its transmission shaft” features an innovative and unique structural design constituted by the axial channel, first radial oil-filling channel and second radial oil-filling channel etc. Based on the innovative structure and technical characteristics, the invention makes an improvement on the prior-art structure in that, when it is needed to add lubrication oil to the transmission shaft, there is no longer a necessity to disassemble the power tool. Therefore, the usage is more convenient and efficient. Moreover, it can effectively avoid the problem of dirt accumulation and block of the oil-filling portion. It is indeed a practical inventive step. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of a preferred embodiment of the transmission shaft structure of the present invention. 
         FIG. 2  is a sectional view of a preferred embodiment of the transmission shaft structure of the present invention. 
         FIG. 3  is a schematic view of a preferred embodiment with disposition of the transmission shaft of the present invention in a power tool. 
         FIG. 4  is an embodiment view with the first radial oil-filling channel and second radial oil-filling channel of the present invention disposed on different sides. 
         FIG. 5  is a usage status view  1  of the present invention. 
         FIG. 6  is a usage status view  2  of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Preferred embodiments of the present invention of a power tool and its transmission shaft are disclosed in  FIGS. 1 to 3 . However, it is to be understood that such embodiments are illustrative only and is not intending to limit the scope of patent claims in any manner. The power tool comprises a main body  80  and a main body A. Said main body A is defined inside the main body  80  in a rotary style, and said main body A is provided with an axial channel  40 , a first radial oil-filling channel  60  and a second radial oil-filling channel  70 . 
     Said main body  80  comprises an enclosure  81  and a grab handle  82  connected to the bottom of the enclosure  81 . A hammer frame  83  is housed inside the internal space of the enclosure  81 . 
     Said main body A comprises a driving section  10 , an acting section  20  and a axle body section  30  between the driving section  10  and the acting section  20 . Said driving section  10  is to be fit into the hammer frame  83  inside the main body  80  in a rotary style, and the acting section  20  relatively extends out of the main body  80 . 
     Said axial channel  40  is defined inside the main body A and extends along the axial direction of the main body A. Said axial channel  40  comprises an internal end  41  and an external end  42 . In particular, the internal end  41  extends out of the end face of the driving section  10 , while the external end  42  extends to the inside of the acting section  20 . 
     Said first radial oil-filling channel  60  is defined at a position on the driving section  10  of the main body A and extends along the radial direction. The internal end of the first radial oil-filling channel  60  and the axial channel  40  are intersected and connected to each other; while the external end the first radial oil-filling channel  60  is connected to the internal space (such as the hammer frame  83  of the main body  80 ) of the power tool preset to be lubricated. 
     Said second radial oil-filling channel  70  is defined at another position on the acting section  20  of the main body A and extends along the radial direction. The internal end of the second radial oil-filling channel  70  and the axial channel  40  are intersected and connected to each other, while the external end of the second radial oil-filling channel  70  extends out of the periphery of the acting section  20  to form an oil-filling hole  71 . 
     Referring to  FIG. 2 , in the embodiment, the first radial oil-filling channel  60  and the second radial oil-filling channel  70  are disposed on the same side. 
     Referring to  FIG. 4 , in the embodiment, the first radial oil-filling channel  60  and the second radial oil-filling channel  70  are disposed on different sides. 
     Referring to  FIG. 5 , in the embodiment, between the corner  21  on the periphery of the free end  201  of the acting section  20  adjacent to the bottom portion of the grab handle  82 , and the corner  822  on the bottom end  821  of the grab handle  82  adjacent to the free end  201  of the acting section  20 , a projection plane L 1  is defined, so that there is a distance W 1  between the oil-filling hole  71  and the projection plane L 1 , and an included angle θ 1  is formed between the projection plane L 1  and the extended axial line L 3  of the second radial oil-filling channel  70 . Said included angle θ 1  is less than 90 degrees. When the projection plane L 1  of the main body  80  touches the ground surface, wall surface or other objects, because the oil-filling hole  71  does not contact the projection plane L 1 , the oil-filling hole  71  will not directly contact the ground surface, wall surface or other objects and dust contamination can be avoided. 
     Referring to  FIG. 6 , in the embodiment, between the other corner  22  on the periphery of the free end  201  of the acting section  20  adjacent to the top portion of the enclosure  81 , and the corner  812  on the top portion  811  of the enclosure  81  adjacent to the free end  201  of the acting section  20 , a projection plane L 2  is defined, so that there is distance W 2  between the oil-filling hole  71  and the projection plane L 2 , and an included angle θ 2  is formed between the projection plane L 2  and the extended axial line L 3  of the second radial oil-filling channel  70 . Said included angle θ 2  is less than 90 degrees. When the projection plane L 2  of the main body  80  touches the ground surface, wall surface or other objects, because the oil-filling hole  71  does not contact the projection plane L 2 , the oil-filling hole  71  will not contact the ground surface, wall surface or other objects and dust contamination can be avoided. 
     Based on said structural constitution and technical characteristics, the practical application of the transmission shaft of a power tool as disclosed in the present invention is depicted in  FIG. 3 . In this embodiment, the main body A is a transmission shaft of a main body  80 . Its driving section  10  is extending into the inside of the main body  80 , so that the external end of the first radial oil-filling channel  60  is connected to the hammer frame  83  of the main body  80  preset to be lubricated. When the user wants to fill lubrication oil into the hammer frame  83 , the flow path is as indicated by the thick solid arrow in the drawing. Firstly, lubrication oil is filled from the oil-filling hole  71 . Then, in sequence, it goes through the second radial oil-filling channel  70 , the internal end  41  of the axial channel  40  and the first radial oil-filling channel  60 , and finally into the hammer frame  83 . In this way, the lubrication oil can be replenished easily and quickly. Also, it is to be noted that, thanks to the unique design of the first radial oil-filling channel  60 , the oil-filling hole  71  is not located on the end face of the acting section  20  but on a lateral position, thus, chances of external dust contamination can be significantly reduced. Moreover, even if the oil-filling hole  71  happens to be contaminated with dust, when the main body A rotates, thanks to the radial extending form of the first radial oil-filling channel  60 , the internal lubrication oil and dust will be thrown out of the oil-filling hole  71  by the centrifugal force generated by the rotation of the main body A. Thus, the oil-filling hole  71  can be automatically cleaned. This is an unexpected advantage over the prior art.