Patent Publication Number: US-11035388-B1

Title: Accelerator-equipped pneumatic cylinder

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an accelerator-equipped pneumatic cylinder, and more particularly to a mechanism used in a pneumatic cylinder for accelerated motion. 
     2. Description of the Related Art 
     A conventional automated machine tool has a spindle configured to be combined with various tools stored in a tool magazine for various processing operations like milling, drilling, and boring. For such a machine tool to use different tools in a tool magazine, a tool changing mechanism is provided to change tools efficiently. During the tool-changing operation, a tool arm first holds a tool that is now attached to the spindle and a pneumatic cylinder working with a multiplier mechanism performs the unclamping operation to make the tool leave the spindle. Then the tool arm moves the tool away for another tool to install. 
     Taiwan Patent Publication No. M441540 discloses a multiplier-equipped unclamping cylinder for addressing the problem of the prior art about insufficient unclamping force. It comprises a first actuator unit, a second actuator unit, and an unclamping unit. It uses a first switch and a second switch to switch between selections, so that the first compressed-air source and a second compressed-air source can simultaneously help the unclamping cylinder to intake air or drain air, thereby accelerating its unclamping operation with a multiplied downward force. 
     However, for accelerating the unclamping operation, the conventional unclamping cylinder has to employ two actuator units, as well as two switches and two compressed-air sources. This causes the resulting unclamping cylinder to have numerous components and become complicated in structure, leading to increased costs. Besides, since the compressed-air sources are not stable enough to hold a constant pressure, once the pressure is lowered, the unclamping operation of the unclamping cylinder is degraded. Hence, the prior art needs to be further improved. 
     SUMMARY OF THE INVENTION 
     To address the foregoing issues, the present invention provides an accelerator-equipped pneumatic cylinder, which features a cylinder block formed with a pressure chamber, and uses a controller to make the pressure chamber and the piston chamber communicated with each other or not. When there is pressure introduced in the pressure chamber and accumulated to a predetermined pressure level, the controller makes the pressure chamber and the piston chamber come into communication with each other, and the accumulated pressure is used to push the pneumatic cylinder at an accelerated speed. 
     The present invention in one embodiment provides an accelerator-equipped pneumatic cylinder, comprising: a cylinder block, having a piston chamber and a pressure chamber; a switch valve, having a valve seat that is installed in the cylinder block and stands between the piston chamber and the pressure chamber, the valve seat having a channel, a controller being installed in the valve seat for making the piston chamber and the pressure chamber communicated with each other or not by opening or closing the channel; and a pneumatic cylinder, having a piston portion receiving in the piston chamber, and having a shaft portion extending outward from one side of the piston portion to be exposed outside the cylinder block, so that when the channel is closed by the controller and the piston chamber and the pressure chamber are not communicated with each other, a pressure medium supplied into the pressure chamber by a pressure source is accumulated to a predetermined pressure level, and at a moment when the channel is opened by the controller and the piston chamber and the pressure chamber come into communication with each other, the piston portion is pushed by the pressure medium at the predetermined pressure level, so that the shaft portion is pushed out the piston chamber at an accelerated speed. 
     Thereby, with the pressure chamber formed in the cylinder block that allows the pressure medium from the pressure source to be introduced and accumulated therein, at the moment when the controller makes the pressure chamber and the piston chamber come into communication with each other, the piston portion is pushed by the pressure medium at the predetermined pressure level and has the shaft portion making a dash outward the piston chamber. In other words, the disclosed cylinder block has the pressure chamber in addition to the piston chamber, and uses the controller to allow the shaft portion to come out the piston chamber with a dash. Even in the event of discontinuation of the external compressed-air source, the accumulated pressure medium can push the shaft portion out the piston chamber. Therefore, the present invention is effective yet involves fewer and simpler components, thereby saving costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an accelerator-equipped pneumatic cylinder of the present invention. 
         FIG. 2  is another perspective view of the accelerator-equipped pneumatic cylinder of the present invention taken from a different angle. 
         FIG. 3  is a cross-sectional view of the accelerator-equipped pneumatic cylinder of the present invention. 
         FIG. 4  is a cross-sectional view taken along Line  4 - 4  in  FIG. 3 . 
         FIG. 5  is a partially cut away view of the accelerator-equipped pneumatic cylinder of the present invention particularly showing two communicating holes. 
         FIG. 6  is a loop diagram of an accelerator-equipped pneumatic cylinder of the present invention, showing that a piston chamber and a pressure chamber are not communicated with each other and a shaft portion of the pneumatic cylinder is retracted into the piston chamber. 
         FIG. 7 , based on  FIG. 6 , is a loop diagram showing that the piston chamber and the pressure chamber are communicated with each other, and the shaft portion of the pneumatic cylinder extends outside the piston chamber. 
         FIG. 8  is an enlarged cut-away view of a part of the accelerator-equipped pneumatic cylinder of the present invention, showing that the piston chamber and the pressure chamber are communicated with each other, and high-pressure medium in the pressure chamber passes through a channel to enter the piston chamber. 
         FIG. 9  is an enlarged cross-sectional view of a part of the accelerator-equipped pneumatic cylinder of the present invention, showing that the high-pressure medium pushes the piston portion at an accelerated speed to make the shaft portion extend outside the piston chamber. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following preferred embodiments when read with the accompanying drawings are made to clearly exhibit the above-mentioned and other technical contents, features and effects of the present invention. Through the exposition by means of the specific embodiments, people would further understand the technical means and effects the present invention adopts to achieve the above-indicated objectives. However, the accompanying drawings are intended for reference and illustration, but not to limit the present invention and are not made to scale. 
     Referring to  FIG. 1  through  FIG. 9 , in one preferred embodiment, the present invention provides an accelerator-equipped pneumatic cylinder  100 . The pneumatic cylinder  100  in the present embodiment is used as an unclamping cylinder, but not limited thereto. The pneumatic cylinder  100  primarily comprises a cylinder block  10 , a switch valve  20 , and a pneumatic cylinder  30 . 
     The cylinder block  10  has a piston chamber  11  and a pressure chamber  12 . In the present embodiment, the cylinder block  10  is columnar. The cylinder block  10  has one end corresponding to the piston chamber  11  provided with a first end cap  13 , and has one end corresponding to the pressure chamber  12  provided with a second end cap  14 . In the present embodiment, the first end cap  13  is shaped as a rectangular block, and the second end cap  14  is also shaped as a rectangular block. The first end cap  13  is formed with a first through hole  131  that is communicated with the piston chamber  11 . 
     The switch valve  20  has a valve seat  21  such installed in the cylinder block  10  that it stands between the piston chamber  11  and the pressure chamber  12 . The valve seat  21  has a channel  211 . In the present embodiment, the valve seat  21  defines therein an operation chamber  212 , whose two ends are provided with a first runner  213  and a second runner  214 . The operation chamber  212  is communicated with the outside of the valve seat  21  through the first runner  213  and the second runner  214 , respectively (as shown in  FIGS. 1 and 4 ). In the present embodiment, the valve seat  21  is shaped as a rectangular block. The valve seat  21  has a flange  215  positionally corresponding to the first runner  213 . The flange  215  protrudes from the valve seat  21 . The valve seat  21  in the present embodiment has two communicating holes  216 . Both of the two communicating holes  216  are communicated with the pressure chamber  12  (as shown in  FIG. 5 ). The communicating holes  216  allow the pressure source P to supply a pressure medium into the pressure chamber  12  where the pressure medium is accumulated to a predetermined pressure level, and also allow the pressure medium in the pressure chamber  12  to be released. The valve seat  21  further has a second through hole  217  communicated with the channel  211 . In the present embodiment, the second through hole  217  and the operation chamber  212  are at two ends of the channel  211 , respectively. Therein, the second through hole  217  and the channel  211  may be communicated with each other, while the operation chamber  212  and the channel  211  are not communicated with each other. 
     The pressure source P (as shown in  FIGS. 6 and 7 ) in the present invention refers to a source of pressure medium, or referred to as a high-pressure fluid, that provides a driving force and the pressure medium is the high-pressure fluid. The high-pressure fluid may be, for example, high-pressure gas (providing a pneumatic force) or high-pressure liquid (providing a hydraulic force). In the present embodiment, the pressure source P supplies high-pressure gas. Additionally, the pressure source P is configured to not only push the drive portion  223 , but also act as a force source for other components. For example, the pressure source P supplies the pressure medium into the pressure chamber  12  where the pressure medium is accumulated to the predetermined pressure level. 
     The switch valve  20  has a controller installed in the valve seat  21 . The controller serves to open and close the channel  211 , thereby making the piston chamber  11  and the pressure chamber  12  communicated with each other or making the piston chamber  11  and the pressure chamber  12  not communicated with each other. In the present embodiment, the controller is a valve stem  22 . The valve stem  22  is installed in the valve seat  21  in an axially movable manner. The valve stem  22  pass through the channel  211 . The valve stem  22  has a small-diameter segment  221 , which is formed on the valve stem  22  by reducing the diameter of the valve stem  22  itself. The small-diameter segment  221  is positionally corresponding to the channel  211 . The valve stem  22  has one end with the small-diameter segment  221  provided with a front retaining ring  222 . The valve stem  22  moves axially in the valve seat  21  to make the front retaining ring  222  enter the channel  211 , thereby closing the channel  211 , or to retract the front retaining ring  222  from the channel  211 , thereby allowing the small-diameter segment  221  to make the channel  211  open. 
     In the present embodiment, the valve stem  22  has one end provided with a drive portion  223 . The drive portion  223  is received in the operation chamber  212 . The pressure source P when supplying the pressure medium into the operation chamber  212  through the first runner  213  pushes the drive portion  223  to drive the valve stem  22  to axially move, thereby making the front retaining ring  222  close the channel  211  (as shown in  FIG. 6 ). Alternatively, the pressure source P when supplying the pressure medium into the operation chamber  212  through the second runner  214 , pushes the drive portion  223  in an opposite direction to make the valve stem  22  axially move and in turn retract the front retaining ring  222  from the channel  211 , thereby opening the channel  211  (as shown in  FIG. 7 ). Moreover, in the present embodiment, the valve stem  22  is provided with a rear retaining ring  224  at its end opposite to the small-diameter segment  221 , so that when the valve stem  22  axially moves to make the front retaining ring  222  close the channel  211 , the channel  211  and the second through hole  217  come into communication with each other. At this time, the channel  211 , with the second through hole  217  acting as its return passage, start to drain the high-pressure gas (as shown in  FIG. 3 ). On the other hand, when the valve stem  22  axially moves to retract the front retaining ring  222  from the channel  211  and thereby open the channel  211 , the rear retaining ring  224  closes the second through hole  217 , so as to prevent the channel  211  from communication with the second through hole  217 . At this time, the channel  211  is prevented from draining the high-pressure gas through the second through hole  217  (as shown in  FIG. 4 ). The pneumatic cylinder  30  has a piston portion  31  received in the piston chamber  11  and a shaft portion  32  extending outward the cylinder block  10  from one side of the piston portion  31 . When the channel  211  is closed by the controller and the piston chamber  11  and the pressure chamber  12  are not communicated with each other, the pressure chamber  12  receives the pressure medium from the pressure source P that is accumulated to the predetermined pressure level. At the moment when the channel  211  is opened by the controller and the piston chamber  11  and the pressure chamber  12  come into communication, the piston portion  31  is pushed by the pressure medium at the predetermined pressure level at an accelerated speed, so the shaft portion  32  is pushed outside the piston chamber  11 . The dash performed by the shaft portion  32  is thus useful to unclamp a tool. The predetermined pressure level refers to a pressure level that is high enough to make the shaft portion  32  perform such dash when it comes out from the piston chamber  11  pressure. The predetermined pressure level is not limited to any constant but determined according to practical unclamping needs. 
     In the present embodiment, the first runner  213  and the second runner  214  are connected to a solenoid valve, respectively, and further connected to the pressure chamber  12  through the solenoid valve. The solenoid valve mainly serves to control whether the pressure source P supplies the pressure by way of the first runner  213  or by way of the second runner  214 . In the present embodiment, the solenoid valve is a two-way solenoid valve  40  (as shown in  FIGS. 6 and 7 ), and is particularly a five-mouth three-place solenoid valve. In the present embodiment, the first through hole  131  formed on the first end cap  13  is communicated with the pressure chamber  12 , and a one-way solenoid valve  50  (as shown in  FIGS. 6 and 7 ) is arranged between the first through hole  131  and the pressure chamber  12 . In the present embodiment, the pressure source P is connected to a communicating hole  216 , while the two-way solenoid valve  40  and the one-way solenoid valve  50  are connected to the other communicating hole  216 , respectively. While the two-way solenoid valve  40  and the one-way solenoid valve  50  are connected to the communicating hole  216  at different sites as depicted in  FIGS. 6 and 7 , this is only for illustration and they are actually connected to the same communicating hole  216 . 
     When powered and magnetically excited, the two-way solenoid valve  40  introduces the pressure medium from the pressure source P into the operation chamber  212  through the first runner  213  so as to push the drive portion  223  (as shown in  FIG. 6 ). The valve stem  22  is then driven to axially move and make the front retaining ring  222  enter the channel  211  to close the channel  211  (as shown in  FIG. 3 ). The high-pressure gas in the operation chamber  212  is drained through the second runner  214 . At this time, the shaft portion  32  returns to the piston chamber  11 , and the high-pressure gas supplied by the pressure source P into the pressure chamber  12  is allowed to build up to the predetermined pressure level. 
     For unclamping operation, as shown in  FIG. 7 , the two-way solenoid valve  40  is power and magnetically excited in an opposite direction, so the pressure source P supplies the high-pressure gas into the operation chamber  212  through the second runner  214  instead to push the drive portion  223  reversely. At this time, the high-press gas in the operation chamber  212  is drained through the first runner  213 . This makes the valve stem  22  to move axially and thereby retracts the front retaining ring  222  from the channel  211 , thereby opening the channel  211  (as shown in  FIGS. 8 and 9 ). At the moment when the channel  211  is opened and the piston chamber  11  and the pressure chamber  12  come into communication with each other, the piston portion  31  is pushed by the high-pressure gas at the predetermined pressure level in a very short period, so the shaft portion  32  makes the dash outward the piston chamber  11  for unclamping a tool. At the time the shaft portion  32  is pushed out the piston chamber  11  for the unclamping operation, the one-way solenoid valve  50  makes the pressure source P and the first through hole  131  become communicated with each other, thereby forming a return passage that enables gas release through the first through hole  131 . 
     Alternatively, before the shaft portion  32  is pushed out the piston chamber  11  for unclamping operation, the one-way solenoid valve  50  may make the pressure source P and the first through hole  131  come into communication with each other in advance, so that the high-pressure gas can be drained from the piston chamber  11  through the first through hole  131 . This allows the shaft portion  32  come out the piston chamber  11  and make the dash more effectively. Furthermore, while the one-way solenoid valve  50  in the depicted embodiment is a stand-alone device that is desiccated in gas release, there may be other embodiments where a solenoid valve is additionally attached to the switch valve  20  for providing the same function of gas release. 
     After the unclamping operation is completed, the two-way solenoid valve  40  introduces the pressure medium from the pressure source P into the operation chamber  212  through the first runner  213 , so as to push the drive portion  223 , which in turn drives the valve stem  22  to move axially to make the front retaining ring  222  enter the channel  211  again, thereby closing the channel  211  (as shown in  FIG. 3 ). The one-way solenoid valve  50  introduces the pressure medium from the pressure source P into the piston chamber  11  reversely to push the piston portion  31 , so as to return the shaft portion  32  into the piston chamber  11  (as shown in  FIG. 6 ), and form a return passage in the second through hole  217  for gas release, thereby returning to the initial state prior to the unclamping operation. 
     As can be seen from the above description, the present invention features that with the cylinder block  10  having the pressure chamber  12 , the pressure medium from the pressure source P can be introduced into the pressure chamber  12  in advance and build up to the predetermined pressure level, so as to act as a driving force that pushes the shaft portion  32  out the piston chamber  11 . In its application for unclamping operation, when a tool attached to a spindle (not shown) is to be changed, the controller (i.e. the valve stem  22  as describe previously) makes the pressure chamber  12  and the piston chamber  11  come into communication with each other. At this time, the piston portion  31  is pushed out the piston chamber  11  by the pressure medium at an accelerated speed in a very short period and thereby makes a dash to fulfill the unclamping operation. The disclosed cylinder block  10  has the pressure chamber  12  in addition to the piston chamber  11 , and uses the controller to allow the shaft portion  32  to come out the piston chamber  11  with a dash. As compared to the foregoing conventional unclamping cylinder that has to be equipped with two actuator units and uses to switches as well as two pressure sources, the present invention involves fewer and simpler components, thereby saving costs. Additionally, since the pressure chamber  12  of the cylinder block  10  allows the pressure medium from the pressure source P to be introduced and accumulated to the predetermined pressure level prior to the intended unclamping operation, even in the event of failure or shortage of the external compressed-air source, the pressure medium accumulated in the pressure chamber  12  can be used to push the shaft portion  32  out the piston chamber  11 , thereby effectively preventing failure of the unclamping operation. 
     The present invention has been described with reference to the preferred embodiments and it is understood that the embodiments are not intended to limit the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present invention should be encompassed by the appended claims.