Abstract:
A force amplifying driver system including an actuator with a powered actuating member mounted for movement along a first distance “X”. A driven member mounted for movement along a second distance or working distance “Y” which is less than the first distance “X”. The powered actuating member is movable through a gap “Z” before being mechanically coupled with the driven member and subsequently moves with the driven member along the second distance “Y”. Energy is transferred from the powered actuating member to the driven member along the second or working distance “Y”. The force amplifying driver system may be used for actuating a fluid jetting dispenser.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/511,058, filed Jul. 27, 2012, which is a national stage entry of International Patent App. No. PCT/US10/59242, filed Dec. 7, 2010, which claims the priority of U.S. Provisional Patent App. No. 61/267,583, filed Dec. 8, 2009, the disclosures of which are incorporated by reference herein. 
     
    
     TECHNICAL FIELD 
       [0002]    Generally, the invention relates to driver systems for moving a driven element with quick, short acceleration, and more specifically, to jetting dispenser or valve in which a valve member is quickly accelerated to dispense or jet material onto a substrate. 
       BACKGROUND 
       [0003]    Drivers for performing various work may be powered in any number of manners, such as pneumatic, hydraulic, electric, magnetic, or combinations thereof. Oftentimes, the drivers for dispensing liquids, such as hot melt materials, comprise pneumatic actuators or electro-magnetic solenoids. 
         [0004]    Various types of jetting dispensers are known such as shown in U.S. Pat. Nos. 5,320,250; 5,747,102; and 6,253,957; and U.S. Publication No. 2006/0157517, the disclosures of which are hereby fully incorporated by reference herein. For many valve and pump devices, the size of the device is important and smaller sizes are typically preferred assuming they will perform the required function. Often, the valve element or piston is directly coupled to move with an actuator such as an air motor or pneumatic actuator, or a solenoid actuator. In such designs, when the overall size of the device is reduced, the forces available to perform the useful work (i.e., movement of the valve element or piston) are also typically reduced. Therefore, the actuator may need to be sized larger than desired if required by the amount of work to be performed. If the actuator is undersized, the performance of the device may be compromised. Direct coupling of the actuator to the device performing the work may also present challenges if the actuator is sensitive to heat and the driven element is part of a heated system. This occurs in the area of hot melt dispensing, for example, where the material being dispensed may be heated to temperatures above 250° F. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention generally provides a force amplifying driver system including an actuator with a powered actuating member mounted for movement along a first distance. A driven member is mounted for movement along a second distance which is less than the first distance. The powered actuating member moves through a gap before mechanically coupling with the driven member and then moves in a mechanically coupled fashion with the driven member along the second distance. In this manner, energy is transferred from the powered actuating member to the driven member along the second distance. During its travel through the gap, the powered actuating member accelerates and creates kinetic energy which is then transferred to the driven member upon mechanical coupling (e.g., contact) and during the movement along the second distance. Thus, the powered actuating member and the driven member are mechanically coupled only during a portion of the overall travel distance of the powered actuating member. The actuator thereby delivers energy to the actuated device or driven member in an amount equal to a larger actuator in a conventional directly coupled driver mechanism. In addition, separating the actuator from the driven member enables the stroke length of the driven member to be shortened and the overall length of the actuated device or driven member to be reduced. 
         [0006]    The driven member may comprise various elements and, in one preferred embodiment, comprises a valve member. The valve member may further comprise a valve stem with a tip engageable with a valve seat. The valve seat is located in a fluid chamber and the tip engages the valve seat at the end of the second distance to discharge a jet or small, discrete amount of the fluid. The actuator may be driven in any suitable manner, such as by using pneumatic or electric based actuators. A biased return mechanism, such as a coil spring, may be used to return the driven member to a starting position and a stop may be provided for stopping the driven member at a starting position designed to create the gap with the powered actuating member. Because the valve stem moves through a shorter stroke as compared to a directly coupled valve stem and actuator delivering the same force, a smaller dot of fluid may be dispensed. This can also be beneficial in various applications in which it would be desirable to dispense smaller, discrete amounts of fluid. 
         [0007]    The invention further involves a method of actuating a driven member including moving an actuating member under power through a gap. The actuating member is then contacted with a driven member at the end of the gap. Once the actuating member and the driven member are mechanically coupled, they are moved together along a working distance to thereby transfer energy from the actuating member to the driven member. Other details of the method will become apparent based on the use of the device as described above and further described below. 
         [0008]    Various additional features and details will become more readily apparent upon review of the following detailed description of an illustrative embodiment, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic, longitudinal cross-sectional view of a fluid jetting dispenser incorporating an illustrative embodiment of the invention and showing the dispenser in a dispensing condition. 
           [0010]      FIG. 2  is a schematic representation similar to  FIG. 1 , but illustrating the dispenser reset in a non-dispensing condition. 
           [0011]      FIG. 3  is a schematic view of a fluid jetting dispenser similar to  FIG. 1 , but showing an alternative, electric actuator in place of the pneumatic actuator. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    The following detailed description will be given in the context of a fluid jetting dispenser, schematically represented, in order to illustrate principles of the invention. However, the principles may be applied to other driver systems for performing other types of work in situations, for example, in which it is desired to quickly accelerate a driven member and in which it may be desirable to minimize the size of the actuator used to move the driven member and/or to provide other benefits. 
         [0013]    Referring to  FIGS. 1 and 2 , a fluid jetting dispenser  10  is illustrated and generally includes an actuator  12  and a jetting valve portion  14 . Dispenser  10  is only schematically illustrated, but may include any desired design features such as any of those illustrated and/or discussed in the above-incorporated patents or publication. As mentioned, actuator  12  may comprise any numerous types of pneumatic or electric powered actuators, for example, but for illustration purposes actuator  12  is schematically shown here as a pneumatic type. The pneumatic actuator  12  generally comprises a cylinder  16  closed at opposite ends by caps  18 ,  20 . A piston  22  is mounted for linear movement within the cylinder  16  and makes an airtight seal with the interior wall of the cylinder  16 . A piston rod  24  is rigidly coupled to the piston  22  and extends through the lower cap  20  and, specifically, through a dynamic air seal  26 . The piston rod  24  is rigidly coupled to the piston  22  using a suitable fastener  28 . Actuator  12  is shown as a dual acting actuator with pressurizable air spaces  30 ,  32  respectively above and below the piston  22 . As is known in the art, pressurized air is introduced through port  31  into the upper air space  30  to drive the piston  22  downward while exhausting air through port  33  from the lower air space  32 . Conversely, pressurized air is introduced through port  33  into the lower air space  32  to drive the piston  22  upwardly while exhausting air through port  31  from the upper air space  30 . Other manners of driving the piston  22  would include the use a conventional spring return mechanism. 
         [0014]    The jetting valve portion  14  is schematically illustrated to include a housing  40  for containing a fluid  42  to be dispensed in a non-contact manner described below. The housing  40  includes a fluid inlet  44  for receiving fluid under pressure. The valve portion  14  further includes a valve stem  46  having a tip  48  engageable with a valve seat  50  to open and close an outlet  52 . Typically, the fluid  42  is pressurized to an extent that will not cause the fluid to ooze or otherwise be dispensed when the valve stem  46  is in the upper position ( FIG. 2 ), but instead will maintain the fluid chamber of the housing  40  in a full condition. As is known with certain types of jetting dispensers, when the valve tip  48  is accelerated against the valve seat  50 , a small amount of fluid  42  will quickly discharge to form a droplet on a substrate (not shown). The opposite end of the valve stem  46  includes a surface  54  adapted to contact a surface  56  of the rod  24  as shown in  FIG. 1 . A coil spring  58  is positioned between a flange  60  and an upper surface of the housing  40  to maintain the valve stem  46  in the raised position shown in  FIG. 2  with a stop member  62  engaged against an inside upper surface of the housing  40 . The valve stem  46  engages a dynamic seal  64  to prevent fluid leakage during its travel through the housing  40 . 
         [0015]    In operation, the fluid jetting dispenser  10  starts in an initial position shown in  FIG. 2  with the surface  56  separated from the surface  54  by a gap “Z.” The piston  22  and attached piston rod  24  are mounted and configured to move through a first distance “X”, while the valve stem  46  is configured and mounted to move through a second distance “Y” shorter than the first distance “X.” The second distance “Y” may be considered the working distance which, in this case, is the stroke length of the jetting valve  14 . In this regard, distance “X” equals distance or gap “Z” plus working distance or stroke length “Y.” When pressurized air is introduced into the upper air space  30  through port  31 , while exhausting air from air space  32  through port  33 , piston  22  and piston rod  24  start to accelerate along distance “X” until they reach maximum acceleration upon contact of surface  56  with surface  54  and after traveling through the gap or distance “Z.” At this point, piston rod  24  is mechanically coupled to valve stem  46  and both travel along distance “Y.” Thus the kinetic energy of piston  22  and its connected piston rod  24  is transferred to valve stem  46  until tip  48  engages valve seat  50 . The resulting acceleration of the tip  48  through distance “Y” and the abrupt stop occurring at valve seat  50  causes a jet of fluid  42  to be dispensed as shown in  FIG. 1 . The fluid  42  may be any viscous fluid, depending on the application, but examples are described in the above-incorporated patents and publication. The piston  22  is then raised by introducing pressurized air into air space  32  through port  33  and exhausting the air from air space  30  through port  31 . As the piston rod  24  is being raised, the spring  58  lengthens under its normal bias to the position shown in  FIG. 2  thereby raising the valve stem  46  in preparation for another dispensing cycle. The piston  22  and attached piston rod  24  are raised until they reach the starting position shown in  FIG. 2  where another dispensing cycle may begin. 
         [0016]      FIG. 3  illustrates an alternative embodiment of a fluid jetting dispenser  10 ′. In this embodiment, the pneumatic actuator  12  of the first embodiment has been replaced with an electric actuator, in the form of a solenoid  70 . The solenoid  70 , illustrated schematically, generally includes an electromagnetic coil  72  surrounding a core or poppet  74 . Activation and deactivation of the solenoid  70 , including the acts of energizing and de-energizing the coil  72  will cause the core or poppet  74  to reciprocate between two positions. These two positions are at the opposite ends of the distance “X” as previously described. During activation, the poppet  74  will move downward through the gap “Z” and then travel along the valve stroke length “Y” during contact between surface  76  of poppet  74  and surface  54  of valve stem  46  while dispensing a fluid droplet  42 . All other reference numerals shown in  FIG. 3  are identical to the numerals referencing the same structure shown and described in  FIGS. 1 and 2 . It will be appreciated that the poppet  74  is analogous to the previously described piston rod  24  and, except for the changes involved in substituting the electric actuator  70  for the pneumatic actuator  12 , all other operations associated with the fluid jetting dispenser  10 ′ are as described above with regard to jetting dispenser  10 . 
         [0017]    While the present invention has been illustrated by a description of the preferred embodiment and while this embodiment has been described in some detail, it is not the intention of the Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features discussed herein may be used alone or in any combination depending on the needs and preferences of the user. This has been a description of illustrative aspects and embodiments the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims.