Patent Publication Number: US-10766129-B2

Title: Torque-adjustable pneumatic tool

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a pneumatic tool, and more particularly to a torque-adjustable pneumatic tool. 
     2. Description of Related Art 
     With reference to  FIG. 22 , a conventional pneumatic tool  70  substantially comprises a body  71 , a driving device  72 , a trigger assembly  73 , and a silencer  74 . The body  71  has a holding chamber  711 , a trigger chamber  712 , an inlet channel  713 , and an outlet channel  714 . The trigger chamber  712  is adjacent to the holding chamber  711  and extends laterally. The inlet channel  713  and the outlet channel  714  communicate with the trigger chamber  712 . The driving device  72  is mounted in the holding chamber  711 , and the trigger assembly  73  is mounted in the trigger chamber  712 . The silencer  74  is mounted on a bottom of the body  71  and communicates with the outlet channel  714 . 
     When the conventional pneumatic tool  70  is in use, the body  71  is connected with an air compressor with a pipe and compressed air can be led into the inlet channel  713 . When the trigger assembly  73  is pressed, the compressed air will be led into the holding chamber  711  to actuate the driving device  72  and the pneumatic tool  70  works. In addition, redundant air will be discharged from the outlet channel  714 . 
     With reference to  FIGS. 22 and 23 , compressed air is the power source for driving the conventional pneumatic tool  70  to operate, but the pressure of the compressed air is unstable. Thus, the torque output by the conventional pneumatic tool  70  is also unstable and will be higher or lower than a desired torque. 
     In addition, the conventional pneumatic tool is usually operated to lock a fastener in two stages. In the first stage, the conventional pneumatic tool is applied to initially lock the fastener with a lower torque. In the second stage, the conventional pneumatic tool is applied to lock the fastener tightly with a high torque. 
     However, the torque output by the conventional pneumatic tool in each stage is not adjustable, so the conventional pneumatic tool is not versatile in use. 
     To overcome the shortcomings, the present invention tends to provide a pneumatic tool to mitigate or obviate the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     The main objective of the invention is to provide a pneumatic tool that is adjustable in torque. 
     The pneumatic tool has a body and a torque adjusting unit. The body has a trigger chamber, a trigger assembly, an inlet channel, and an outlet channel. The trigger chamber is defined in the body. The trigger assembly is mounted in the trigger chamber. The inlet channel and the outlet channel communicate with the trigger chamber. The torque adjusting unit is connected with a bottom of the body, is mounted on one end of the outlet channel, and has a silencer, a piston rod, a piston sleeve, and a spring. The silencer is mounted detachably on the bottom of the body and has a discharging chamber. The piston rod is connected adjustably with the silencer and extends into the discharging chamber. The piston sleeve is mounted around the piston rod and is axially moveable relative to the piston rod. The spring is mounted around the piston sleeve and has two ends abutting respectively the piston sleeve and the silencer. 
     Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view in partial section of a pneumatic tool in accordance with the present invention; 
         FIG. 2  is an enlarged exploded perspective view of the torque adjusting unit of the pneumatic tool in  FIG. 1 ; 
         FIG. 3  is an enlarged side view in partial section of the pneumatic tool in  FIG. 1 ; 
         FIG. 4  is an enlarged operational side view in partial section of the pneumatic tool in  FIG. 1 ; 
         FIG. 5  is an enlarged operational side view of the pneumatic tool in  FIG. 4 ; 
         FIG. 6  is an enlarged operational cross sectional side view of the pneumatic tool in  FIG. 4 ; 
         FIG. 7  is another enlarged operational cross sectional side view of the pneumatic tool in  FIG. 4  showing the torque adjusting unit in the first operation stage of the pneumatic tool; 
         FIG. 8  is another enlarged operational cross sectional side view of the pneumatic tool in  FIG. 4  showing the torque adjusting unit in the second operation stage of the pneumatic tool; 
         FIG. 9  is a curved diagram of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1 ; 
         FIG. 10  shows enlarged operational cross sectional side views of the pneumatic tool in  FIG. 4  showing that the piston rod adjusting member is adjusted in the first operational stage of the pneumatic tool; 
         FIG. 11  shows enlarged operational cross sectional side views of the pneumatic tool in  FIG. 4  showing that the piston rod adjusting member is adjusted in the second operational stage of the pneumatic tool; 
         FIG. 12  shows curved diagrams of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1  after the piston rod adjusting member is adjusted; 
         FIG. 13  shows another curved diagrams of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1  after the piston rod adjusting member is adjusted; 
         FIG. 14  shows enlarged operational cross sectional side views of the pneumatic tool in  FIG. 4  showing that the piston sleeve adjusting member is adjusted in the second operational stage of the pneumatic tool; 
         FIG. 15  shows curved diagrams of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1  after the piston sleeve adjusting member is adjusted; 
         FIG. 16  shows another enlarged operational cross sectional side views of the pneumatic tool in  FIG. 4  showing that the piston sleeve adjusting member is adjusted in the second operational stage of the pneumatic tool; 
         FIG. 17  shows another curved diagrams of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1  after the piston sleeve adjusting member is adjusted; 
         FIG. 18  shows enlarged operational cross sectional side views of the pneumatic tool in  FIG. 4  showing that the piston rod adjusting member and the piston sleeve adjusting member are adjusted at the same time; 
         FIG. 19  shows curved diagrams of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1  after the piston sleeve adjusting member and the piston rod adjusting member are adjusted at the same time; 
         FIG. 20  shows another enlarged operational cross sectional side views of the pneumatic tool in  FIG. 4  showing that the piston rod adjusting member and the piston sleeve adjusting member are adjusted at the same time; 
         FIG. 21  shows another curved diagrams of torque, rotation speed, and actuating time of the pneumatic tool in  FIG. 1  after the piston sleeve adjusting member and the piston rod adjusting member are adjusted at the same time; 
         FIG. 22  is a side view in partial section of a conventional pneumatic tool; and 
         FIG. 23  is a curved diagram of torque, rotation speed, and actuating time of the conventional pneumatic tool in  FIG. 22 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
     With reference to  FIGS. 1 to 4 , a pneumatic tool in accordance with the present invention comprises a body  10 , a signal pressure transmitting unit  20 , and a torque adjusting unit  30 . 
     With reference to  FIGS. 1 and 2 , the body  10  may be conventional and has a trigger chamber  12 , a trigger assembly  11 , an inlet channel  13 , and an outlet channel  14 . The trigger chamber  12  is defined in the body  10 . The trigger assembly  11  is mounted in the trigger chamber  12  and comprises a valve sleeve  110 , a valve core  111 , a piston pin  112 , and a button  113 . The valve core  111  is mounted in the valve sleeve  110 . The piston pin  112  is mounted through the valve core  111 . The button  113  is mounted on an end of the piston pin  112 . The inlet channel  13  communicates with the trigger chamber  12 , and the outlet channel  14  communicates with the trigger chamber  12 . In operation, the body  10  is connected with an air compressor with a pipe. When the button  13  is pressed, compressed air can be led into the trigger chamber  12  via the inlet channel  13  and is applied to actuate a driving device mounted in the body  10  to generate torque for working. 
     The signal pressure transmitting unit  20  is mounted in the trigger chamber  12 , is connected with the valve core  111 , and comprises a positioning member  21 , a signal element  22 , and a guiding tube  23 . The positioning member  21  may be a bolt and is mounted on a bottom of the valve core  111 . The signal element  22  is mounted on the bottom of the valve core and is co-axial with the positioning member  21 . The signal element  22  has a T-shaped cross section and is screwed with the positioning member  21 , such that the position of the signal element  22  relative to the valve core  111  can be adjusted by rotating the positioning member  21 . The guiding tube  23  has a first end connected with the signal element  22  and a second end extending into the outlet channel  14  in the body  10 . 
     With reference to  FIGS. 1 and 2 , the torque adjusting unit  30  is connected with a bottom of the body  10 , is mounted on an opening  141  of the outlet channel  14 , and is connected with the signal pressure transmitting unit  20  by the guiding tube  23 . The torque adjusting unit  30  comprises a silencer  31 , a piston rod  32 , a piston sleeve  33 , a blocking pin  34 , a spring  35 , a piston rod adjusting member  36 , and a piston sleeve adjusting member  37 . 
     With reference to  FIGS. 2 and 3 , the silencer  31  is mounted detachably on the bottom of the body  10  and has a sleeve body  311 , a connection segment  312 , a connection hole  313 , a connection thread  314 , a discharging chamber  315 , and a bottom cap  316 . The connection segment  312  is formed on and protrudes from a top end of the sleeve body  311 . The connection hole  313  is defined in the connection segment  312  and is threaded. The connection thread  314  is formed around the connection segment  312 , such that the sleeve body  311  can be connected detachably with the bottom of the body  10  by the connection thread  314 . The discharging chamber  315  is defined in the sleeve body  311 . The bottom cap  316  is mounted on a bottom end of the sleeve body  311 . 
     The piston rod  32  is connected rotatably and adjustably with the silencer  31  and has a first end and a second end. The first end is provided with a first adjusting thread  321 , and the second end is provided with a second adjusting thread  322 . The piston rod  32  further has a guiding channel  323 , an abutting flange  324 , a discharging hole  325 , and a pin thread  326 . The guiding channel  323  is axially defined through the piston rod  32 . The abutting flange  324  is formed around an outer surface at a middle of the piston rod  32 . The discharging hole  325  is defined radially in the piston rod  32  at a position being adjacent to the abutting flange  324  and communicates with the guiding channel  323 . The pin thread  326  is defined in a bottom end of the guiding channel  323 . The first adjusting thread  321  is screwed with the connection hole  313  in the silencer  31 , and the first end of the piston rod  32  extends out of a top end of the silencer  31 . 
     The piston sleeve  33  is mounted in the discharging chamber  315  of the silencer  31 , is mounted around the piston rod  32 , and is axially moveable relative to the piston rod  32 . The piston sleeve  33  has a guiding segment  331 , a discharging space  332 , and an abutting rib  333 . The guiding segment  331  is formed on and around a top end of the piston sleeve  33  and has a conical top surface. The discharging space  332  is defined in the piston sleeve  33 . The abutting rib  333  is annular and is formed on and protrudes from an inner surface at a middle of the discharging space  332 . The abutting flange  324  of the piston rod  32  is mounted in the discharging space  332  and selectively abuts the abutting rib  333 . 
     The blocking pin  34  is mounted in the guiding channel  323  of the piston rod  32  and comprises a blocking segment  341 , a pin outer thread  342 , and a through hole  343 . The blocking segment  341  is formed on an upper portion of the blocking pin  34  and extends into the guiding channel  323  of the piston rod  32  to form a gap between an outer surface of the blocking segment  341  and the inner surface of the guiding channel  323 . The pin outer thread  342  is formed around a lower portion of the blocking pin  34  and is screwed with the pin thread  326  in the piston rod  32 . The through hole  343  is defined radially in the pin outer thread  342 . The spring  35  is mounted around the piston sleeve  33  and has two ends abutting respectively the guiding segment  331  of the piston sleeve  33  and the bottom cap  316  of the silencer  31 . 
     The piston rod adjusting member  36  is screwed with the first adjusting thread  321  on the piston rod  32  and selectively abuts the top of the connection segment  312 . With the rotation of the piston rod adjusting member  36 , the axial position of the piston rod  32  relative to the silencer  31  can be adjusted. The piston sleeve adjusting member  37  is screwed with the second adjusting thread  322  on the piston rod  32 . With the rotation of the piston sleeve adjusting member  37 , the axial position of the piston sleeve  33  relative to the piston rod  32  can be adjusted. 
     With reference to  FIGS. 4 and 5 , in use, the pneumatic tool is connected with a compressed air source. When the button  113  is pressed, the piston pin  112  will be axially moved relative to the valve sleeve  110  and the valve core  111 . At this time, the compressed air will enter the trigger chamber  12  via the inlet channel  13 . Consequently, the compressed air can be applied to drive the driving device to output a torque in a first operation stage. 
     With reference to  FIGS. 5 to 7 , during the operation of the pneumatic tool, some of the compressed air will enter the signal pressure transmitting unit  20 , wherein the pressure of the compressed air entering into the signal pressure transmitting unit  20  is defined as the signal pressure. The signal pressure will be led into the torque adjusting unit  30  via the guiding tube  23 . 
     While the pneumatic tool is applied to output the torque in the first operation stage, the redundant compressed air that is not applied to drive the driving device will be discharged into the outlet channel  14  and enters into the torque adjusting unit  30 . At this time, an original height H is defined between a top of the piston rod  32  and a top of the piston rod adjusting member  36 . When the original height H is not changed and the signal pressure is equal to the pressure of the discharging air, the discharging air will push the piston sleeve  33  to move slightly and the piston sleeve  33  is moved downward relative to the piston rod  32 . Consequently, a discharging gap O is formed between the silencer  31  and the piston sleeve  33  to discharge the discharging air. At this time, the amount of the discharging air is small, and the amount of the compressed air into the body  10  is also small. Thus, the pneumatic tool can be controlled at a low speed and a low torque output. 
     With reference to  FIGS. 7 and 8 , to enlarge the output torque, the amount of the compressed air input into the inlet channel  13  is increased such that the pneumatic tool can output a large torque in the second operation stage. Consequently, the amount of the compressed air entering into the signal pressure transmitting unit  20  is also increased. The signal pressure enters into the torque adjusting unit  30  via the guiding tube  23  and passes through the gap around the blocking pin  34 , and the signal pressure will enter into the discharging space  332  in the piston sleeve  33  via the discharging hole  325  in the piston rod  32 . When the signal pressure and the pressure of the discharging air are increasing, the force applied to push the piston sleeve  33  downward will be larger than the resistant force of the spring  35 . Thus, the piston sleeve  33  will be pushed to move downward relative to the piston rod  32 , so the discharging gap O will be enlarged and the amount of the discharging air is increased. Accordingly, the amount of the compressed air entering into the body  10  is also increased, and the rotation speed and the torque of the pneumatic tool will be increased as shown in  FIG. 9 . Therefore, the pneumatic tool in accordance with the present invention can provide different rotation speeds and torques at different operation stages to fit with different use demands. 
     With reference to  FIGS. 10 to 13 , the rotation speeds and the torques at the operation stages can be adjusted by rotating the piston rod adjusting member  36 . When the piston rod adjusting member  36  is rotated and the piston rod  32  is moved upward and axially relative to the silencer  31 , the original height H will be increased to a first height H 1  as shown on the left of  FIG. 10 . Accordingly, the discharging gap O will be reduced in both the first operation stage and the second operation stage. Thus, the rotation speed will be reduced, and the output torque is also decreased. 
     On the contrary, when the piston rod adjusting element  36  is rotated and the piston rod  32  is moved downward relative to the silencer  31 , the original height H will be decreased to a first height H 1  as shown on the right of  FIG. 10 . The first height H 1  may approach 0. At this time, the discharging gap O is enlarged in both the first operation stage and the second operation stage, and the amount of the discharging air is increased. With reference to  FIG. 13 , the rotation speed in the first operation stage is increased, and the output torque is also increased and is larger than a predetermined torque. 
     With reference to  FIGS. 14 to 17 , the rotation speeds of the pneumatic tool may be further adjusted in the second operation stage by rotating the piston sleeve adjusting member  37 . When the piston sleeve adjusting member  37  is rotated and the piston sleeve  33  is moved upward relative to the piston rod  32 , a second height H 2  between a bottom of the piston rod  32  and a bottom of the piston rod adjusting member  36  is increased. When the second height H 2  is increased, the dead end of the movement of the piston sleeve  33  will be moved upward and the movement distance of the piston sleeve  33  is reduced. Thus, the discharging gap O is reduced, and the amount of the discharging air will be reduced. Accordingly, the rotation speed of the pneumatic tool will be reduced, and the output torque will also be decreased and is smaller than a predetermined torque. 
     On the contrary, with reference to  FIGS. 16 and 17 , when the piston sleeve adjusting element  37  is rotated and the piston sleeve  33  is moved downward relative to the piston rod  32 , the second height H 2  will be decreased even to 0. Consequently, the discharging gap O will be enlarged, and the amount of the discharging air will be increased. Accordingly, the rotation speed and the torque of the pneumatic tool will be increased. 
     With reference to  FIGS. 18 to 21 , the piston rod adjusting member  36  and the piston sleeve adjusting member  37  can be rotated at the same time, such that the rotation speeds in the first operation stage and the second operation stage can be adjusted and the output torques are also adjusted. With reference to  FIGS. 18 and 19 , when the piston rod adjusting member  36  is rotated to increase the first height H 1  and the piston sleeve adjusting member  37  is rotated to decrease the second height H 2 , the rotation speed in the first operation stage will be reduced and the rotation speed in the second operation speed is increased. Accordingly, the output torque approaches the predetermined torque. 
     On the contrary, with reference to  FIGS. 20 and 21 , when the piston rod adjusting member  36  is rotated to decrease the first height H 1  and the piston sleeve adjusting member  37  is rotated to increase the second height H 2 , the rotation speed in the first operation stage is increased and the rotation speed in the second operation stage is decreased. Accordingly, the output torque also approaches the predetermined torque. 
     With such an arrangement, the torque adjusting unit  30  in accordance with the present invention can be adjusted by rotating the piston rod adjusting member  36  and the piston sleeve adjusting member  37  individually or simultaneously, such that the pneumatic tool can output different torques at different operation stages, and the pneumatic tool in accordance with the present invention is versatile in use. 
     In addition, the pneumatic tool in accordance with the present invention has the adjusting function without using electric components or wires, and is easily achieved by modifying a conventional pneumatic tool without increasing the whole weight and volume of the conventional pneumatic tool. 
     Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.