Patent Publication Number: US-2012037469-A1

Title: Air pressure buffer stick

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a buffer mechanism, and more particularly to an air pressure buffer stick. 
     2. Description of the Prior Art 
     Referring to  FIG. 1 , a first conventional air pressure buffer stick  10  comprises a pressure cylinder  11 , a piston lever  12 , and a seal cover  13 . The pressure cylinder  11  is formed with a through hole  111  in a first end thereof, and a second end of the pressure cylinder  11  is formed with an opening  112 . The piston lever  12  includes a piston  121  connected to a lever portion  122  and is disposed in the pressure cylinder  11  through the opening  112  of the pressure cylinder  11 , and then the seal cover  13  seals the opening  112 . The lever portion  122  of the piston lever  12  is connected to other mechanisms. By such arrangements, a friction will be produced between the piston  121  of the piston lever  12  and the inner surface of the pressure cylinder  11  when the piston lever  12  extends out of the pressure cylinder  11 , which will slow down the moving speed of the lever portion  122  relative to the pressure cylinder  11 , offering a buffer effect. When the piston lever  12  retracts into the pressure cylinder  11 , the air in the pressure cylinder  11  will be discharged through the through hole  111 , similarly, a friction will be produced between the piston  121  of the piston lever  12  and the inner surface of the pressure cylinder  11  to slow down the moving speed of the piston lever  12  relative to the pressure cylinder  11 , offering the buffer effect. 
     Referring to  FIG. 2 , a second conventional air pressure stick  20  comprises a pressure cylinder  21 , a piston lever  22  and a seal cover  23 . The pressure cylinder  21  is formed in an inner surface thereof with plural air guide channels  211 . The pressure cylinder  21  includes an opening  212 . The piston lever  22  includes a piston  221  connected to a lever portion  222  and is disposed in the pressure cylinder  21  through the opening  212 , and the seal cover  23  seals the opening  212 . By such arrangements, when the piston lever  22  is moved, a friction will be produced between the piston  221  of the piston lever  22  and the inner surface of the pressure cylinder  21  to slow down the moving speed of the piston lever  22  relative to the pressure cylinder  22 , offering the buffer function, meanwhile, the air guide channels  211  can guide the air into the pressure cylinder  21  to prevent the pressure cylinder  21  from failing due to vacuum effect. 
     As known from the abovementioned, the conventional air pressure sticks  10 , both offer the buffer effect through the friction produced between the inner surface of the pressure cylinder and the piston of the piston lever, but they cannot effectively keep the air in the air pressure sticks to produce the air pressure buffer effect. In addition, such an operating manner might cause the piston of the piston lever to wear out quickly, which greatly weakening the buffer effect of the air pressure stick, as result of this, the user needs to replace the piston lever frequently, leading to the increase of the cost. 
     The present invention has arisen to mitigate and/or obviate the afore-described disadvantages. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide an air pressure buffer stick whose buffering force is provided by the friction of the piston and the counterforce of the air, reducing the wear rate of the piston while extending the service life of the air pressure buffer stick. 
     To achieve the above objective, an air pressure buffer stick in accordance with the present invention comprises a pressure cylinder, a piston and a moving rod. 
     The pressure cylinder is a pipe and formed with an open end. 
     The piston is in the form of a cylinder defined in an outer periphery thereof with an annular groove and deformable. The piston is formed with an air through hole and disposed in the moving space of the pressure cylinder. 
     The moving rod includes a piston connecting element and a rod element at both ends thereof. The piston connecting element includes an inserting portion and an abutting portion at both ends thereof. The inserting portion of the moving rod is inserted into the air through hole of the piston, and the abutting portion abuts outside the piston. The abutting portion is formed with at least one first ventilated unit, and the inserting portion is formed with at least one second ventilated unit. The rod element of the moving rod extends out of the open end of the pressure cylinder. 
     The pressure cylinder has an end opposite the open end thereof closed, and the piston is formed with the air through hole, so that when the moving rod together with the piston moves, the counterforce of the air will make the piston deform. The friction produced between the piston and the pressure cylinder and the counterforce of the air flowing therethrough both provide the buffering force of the air pressure buffer stick, reducing the wear rate of the piston while extending the service life of the air pressure buffer stick. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an assembly view of a first conventional air pressure buffer stick; 
         FIG. 2  is a cross-sectional view of a second conventional air pressure buffer stick; 
         FIG. 3  is an exploded view of an air pressure buffer stick in accordance with a first embodiment of the present invention; 
         FIG. 4  is a cross-sectional view of the air pressure buffer stick in accordance with the first embodiment of the present invention; 
         FIG. 5  is an operational cross-sectional view of the air pressure buffer stick in accordance with the first embodiment of the present invention; 
         FIG. 6  is a cross-sectional view showing a flow path of the air when the air is subjected to a relatively smaller pressure to make the moving rod and the piston be fitted in a loose manner; 
         FIG. 7  is a cross-sectional view showing a flow path of the air when the air is subjected to a relatively greater pressure to make the moving rod and the piston be closely fitted; and 
         FIG. 8  is a cross-sectional view of an air pressure buffer stick in accordance with a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
     Referring to  FIGS. 3-7 , an air pressure buffer stick in accordance with a first embodiment of the present invention comprises a pressure cylinder  30 , a piston  40 , a moving rod  50  and a seal cover  60 . 
     The pressure cylinder  30  is a pipe and includes a moving space  31  and an open end  32 . 
     The piston  40  is in the form of a cylinder defined in an outer periphery thereof with an annular groove and formed with an air through hole  41 . The piston  40  is deformable and made of a material selected from the group consisting of rubber, polyurethane and silica gel. In the present embodiment, the piston  40  is made of rubber. The air through hole  41  of the piston  40 , in order, includes a first expansion segment  411 , a second expansion segment  412  and a third expansion segment  413 . The first expansion segment  411  and the third expansion segment  413  are both tapered toward the second expansion segment  412 , and a diameter of the second expansion segment  412  is smaller than that of both the first expansion segment  411  and the third expansion segment  413 . The piston  40  is disposed in the moving space  31  of the pressure cylinder  30 . 
     The moving rod  50  includes a piston connecting element  51  and a rod element  52  at both ends thereof. The piston connecting element  51  includes an inserting portion  511  and an abutting portion  512  at both ends thereof. An outer diameter of the inserting portion  511  is sized correspondingly to an inner diameter of the piston  40 , and an outer diameter of the abutting portion  512  is greater than that of the inserting portion  511 . Between the inserting portion  511  and the abutting portion  512  is connected a concave middle portion  513 . An outer diameter of the middle portion  513  is smaller than the inner diameter of the piston  40 . The inserting portion  511  of the moving rod  50  is inserted into the air through hole  41  through the third expansion segment  413  of the piston  40 , and the abutting portion  512  abuts outside the piston  40 . The abutting portion  512  is formed with at least one first ventilated unit  514 , and the first ventilated unit  514  is formed with plural spaced notches  514   a  in a circumference of the abutting portion  512 , or formed with a through hole  514   b  in the abutting portion  512 . In addition, the first ventilated unit  514  can also be formed with both the plural spaced notches  514   a  and the through hole  514   b  at the same time. The inserting portion  511  is formed with at least one second ventilated unit  515 , and the second ventilated unit  515  of the inserting portion  511  is formed with plural spaced notches  515   a  in a circumference of the inserting portion  511 , or formed with a through hole  515   b  in the inserting portion  511 . In addition, the second ventilated unit  515  can also be formed with both the spaced notches  515   a  and the through hole  515   b  in the inserting portion  511  at the same time. The abutting portion  512  is formed in a surface thereof facing the inserting portion  511  with a circulation channel  516  which is in communication with the notch-formed first ventilated unit  514 . The moving rod  50  is connected to the piston  40  and disposed in the pressure cylinder  30  with the rod element  52  of the moving rod  50  extending out of the open end  32  of the pressure cylinder  30 . 
     The seal cover  60  is centrally formed with a through hole  61  through which the seal cover  60  is engaged on the rod element  52  of the moving rod  50  to seal the open end  32  of the pressure cylinder  30 . 
     The aforementioned is the summary of the positional and structural relationship of the respective components of the preferred embodiment in accordance with the present invention. After the moving rod  50  and the piston  40  are combined, the moving rod  50  can linearly move within the pressure cylinder  30  together with the piston  40 . When the moving rod  50  together with the piston  40  moves outwards relative to the pressure cylinder  30 , a friction will be produced between the piston  40  and an inner surface of the pressure cylinder  30 , and the air will be drawn into the pressure cylinder  30 , offering the buffer effect. When the moving rod  50  together with the piston  40  moves inwards relative to the pressure cylinder  30 , since the pressure cylinder  30  is filled with the air, the piston  40  will compress the air, and then the air will enter the piston  40  only through the air though hole  41 . Since the moving rod  50  includes the concave middle portion  513 , when the moving rod  50  is inserted in the piston  40 , between the middle portion  513  of the moving rod  50  and the inner surface of the piston  40  is defined a clearance, which allows the moving rod  50  to rotate freely in the piston, presenting a loose-fit state. As a result, if the piston  40  is pushed by a relatively smaller force, that is, if the piston  40  applies a relatively smaller pressure to the air, the air will flow out through the air through hole  41  of the piston  40  and the clearance between the piston  40  and the piston connecting element  51 , so that the friction between the piston  40  and the inner surface of the pressure cylinder  30 , and the counterforce of the air flowing therethrough can both offer the buffer effect. 
     If the piston  40  is pushed into the pressure cylinder  30  by a relatively greater pressure, that is, if the piston  40  applies a relatively greater pressure on the air, the counterforce of the air is relatively greater. Since the piston  40  includes the air through hole  41 , while pushing the air into the pressure cylinder  30  through the air through hole  41  of the piston  40 , the counterforce of the air will make the first expansion segment  411  of the air through hole  41  of the piston  40  expand, at this moment, the friction between the piston  40  and the pressure cylinder  30  will provide a first buffering force. When continuing flowing through the air through hole  41 , the air will flow from the first expansion segment  411  into the third expansion segment  413  through the second expansion segment  412 . Since the diameter of the second expansion segment  412  is smaller than that of both the first and the third expansion segments  411 ,  413 , the air will be compressed and then flow into the third expansion segment  413 . After that, when the air enters the third expansion segment  413 , the third expansion segment  413  will be made to expand, so that the piston  40  will provide a second buffering force, that is, between the deformed piston  40  and the inner surface of the pressure cylinder  30  is produced a friction again, and the air which hasn&#39;t entered the piston  40  will again apply a counterforce onto the piston  40 . Subsequently, the air will flow from the third expansion segment  413  into the clearance between the middle portion  513  of the piston connecting element  51  and the piston  40  through the second ventilated unit  515  of the inserting portion  511  of the piston connecting element  51 , and then the air will continue to flow toward the abutting portion  512  and finally flow out of the pressure cylinder  30  through the circulation channel  516  and the first ventilated unit  514 . To summarize, the air pressure buffer stick in accordance with the present invention can utilize both the friction produced between the piston  40  and the inner surface of the pressure cylinder  30  and the counterforce of the air to offer the buffering force, that is, the counterforce of the air and the friction together provide the buffering force of the air pressure buffer stick in accordance with the present invention, so that the wear rate of the piston  40  can be reduced, and the buffer effect of the air pressure buffer stick can be improved, furthermore, the replacement rate of the parts is correspondingly reduced, effectively reducing the cost while extending the service life of the air pressure buffer stick. 
     Please refer to  FIG. 8  which illustrates an air pressure buffer stick in accordance with a second embodiment of the present invention, the piston  40  is in the form of a straight pipe and still includes the air through hole  41 , so that the present embodiment of the present invention can offer the same function as the previous embodiment. 
     While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.