Abstract:
A vacuum cup assembly that generates a local vacuum using a prime mover that may be an electrical motor or a solenoid. The vacuum cup may have one or more ports to remove and vent air between the cup and the atmosphere. The prime mover drives a piston or a flexible membrane, which may be a diaphragm, through one or more reciprocating cycles to generate the local vacuum. The vacuum cup assembly may be used to form a temporary attachment to a work piece, the act on the work piece, such as by moving the work piece, and then release the work piece from the vacuum cup assembly. The vacuum cup assembly disclosed herein is self-contained inasmuch as the assembly may have a power source, such as a battery, located on a housing. This makes its operation quiet and effective.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/080,361 filed Nov. 16, 2014. This prior application is hereby incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    (Not Applicable) 
       THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    (Not Applicable) 
       REFERENCE TO AN APPENDIX 
       [0004]    (Not Applicable) 
       BACKGROUND OF THE INVENTION 
       [0005]    The present invention relates generally to the field of automation systems, and more specifically to vacuum cup assemblies that create a temporary mechanical attachment to an object in order to permit equipment to lift such objects in order to move them. 
         [0006]    Many vacuum cup assemblies on the market are venturi-operated, which require an air flow to generate a vacuum via a venturi effect. Thus, each assembly must have a source of compressed air or must be connected to a vacuum source, both of which typically occur through gas hoses. 
         [0007]    The use of compressed air may be too noisy for certain environments, because the operation of numerous venturi-operated cup assemblies can damage human auditory systems. Furthermore, in many applications, the use of venturi-operated cup assemblies can move sufficient air to cause small particles to become contaminants in medical and electronic products near which the cup assemblies are operated. Furthermore, compressed air systems require significant maintenance. Still further, some users of cup assemblies may not be willing or able to extend an air hose to an assembly. 
         [0008]    The prior art includes devices that deform suction cups, such as the conventional suction cup used to mount electronic and other devices to automotive windows. However, such mechanisms do not provide satisfactory results in some circumstances. Furthermore, because some users wish to use their own proprietary cup, such conventional suction cups do not suffice. Such deformable cups may also lack a continual vacuum draw, which is sometimes desired. 
         [0009]    Therefore, there is a need for a vacuum cup system in a quiet and clean working environment. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Disclosed herein is a vacuum cup assembly having a vacuum cup with a wall terminating at one end in a rim configured to seat against a work piece for forming a temporary attachment to the work piece. The vacuum cup has a concave fluid chamber formed within the vacuum cup wall. The vacuum cup is mounted to the housing, such as to a first wall of the housing. In a preferred embodiment, a second housing wall has a cylindrical bore therein, which at least partially defines a variable volume chamber that is fluidically connected to the concave fluid chamber in the vacuum cup. A sidewall, which may be a piston or a flexible membrane, is moveably mounted to the housing wall and partially defines the variable volume chamber. A prime mover, which may be a rotary motor or a solenoid, is mounted to the housing and to the sidewall, and may selectively displace the sidewall relative to the housing, such as by a linkage connecting the prime mover and the sidewall. Displacement of the sidewall modifies the volume of the variable volume chamber and thereby modifies the fluid pressure in the concave fluid chamber. 
         [0011]    The piston may be sealingly and slidably mounted in the cylindrical bore of the housing wall. As an alternative, the sidewall may be a flexible membrane sealingly mounted to the housing wall in the cylindrical bore. Both sidewalls form a boundary of the variable volume chamber. 
         [0012]    One or more valves may be mounted in the sidewall, in the housing, or in both the sidewall and the housing to permit fluid to flow through the valve from the variable volume chamber. This valve can selectively pass air into the variable volume chamber from the atmosphere, out of the variable volume chamber to the atmosphere or to the internal regions of the housing. 
         [0013]    In one aspect, a vacuum cup assembly may comprise a housing having a chamber including a cylinder wall, wherein a linear or rotary prime mover, such as a motor or solenoid, moves a piston in the chamber. The prime mover may mount to the housing, and the housing may have an opening at one side or the housing may comprise a base to which the prime mover mounts. The housing may have a base and an aperture through the base on the side of the housing opposite the motor. A passage through the base extends into the vacuum cup. 
         [0014]    In another aspect, a vacuum cup assembly may comprise a housing having a chamber including a cylinder wall, wherein the housing has an opening at one side where a solenoid moves a piston in the chamber. The housing may have a base and an aperture through the base on the side of the housing opposite the solenoid, and it is contemplated for the solenoid or motor to be mounted to the housing adjacent the aperture and base or on the same side of the housing as the aperture and base. A passage through the base extends into the vacuum cup. 
         [0015]    In another aspect, a vacuum cup assembly comprises a housing having a chamber, wherein the housing has an opening at one side where an electrical motor connects to and may move a diaphragm in the chamber. The housing may have a base and an aperture through the base on the side of the housing opposite the motor. 
         [0016]    In another aspect, a vacuum cup assembly comprises a housing having a chamber, wherein the housing has an opening at one side where a solenoid connects to and may move a diaphragm in the chamber. The housing may have a base and an aperture through the base on the side of the housing opposite the motor. 
         [0017]    The embodiments of the present invention provide a vacuum cup assembly or system of providing suction force to pick up a work piece, which is not limited to any size, shape, weight or useful purpose, and then release the work piece with precision. The vacuum cup assembly may have a power source that is located on the vacuum cup assembly, thereby avoiding the need for connecting wires, air hoses or any other structure to power the vacuum cup assembly. The power source may be batteries or any electrical, chemical, mechanical or other energy or potential energy storage device. The above, and other, features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0018]      FIG. 1  is a cross-sectional view illustrating a vacuum cup assembly in accordance with an embodiment of the present invention. 
           [0019]      FIG. 2  is a cross-sectional view illustrating a vacuum cup assembly in accordance with an embodiment of the present invention. 
           [0020]      FIG. 3  is a cross-sectional view illustrating a vacuum cup assembly in accordance with an embodiment of the present invention. 
           [0021]      FIG. 4  is a cross-sectional view illustrating a vacuum cup assembly by using a fan in accordance with an embodiment of the present invention. 
           [0022]      FIG. 5  is a cross-sectional view illustrating a vacuum cup assembly by using a cam in accordance with an embodiment of the present invention. 
           [0023]      FIG. 6  is a cross-sectional view illustrating a vacuum cup assembly by using a lever in accordance with an embodiment of the present invention. 
           [0024]      FIG. 7  is a cross-sectional view illustrating a vacuum cup assembly in accordance with a still an embodiment of the present invention. 
           [0025]      FIG. 8  is a cross-sectional view illustrating a vacuum cup assembly in accordance with an embodiment of the present invention. 
           [0026]      FIG. 9  is a cross-sectional view illustrating a vacuum cup assembly in accordance with an embodiment of the present invention. 
       
    
    
       [0027]    In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or terms similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    U.S. Provisional Application No. 62/080,361 filed Nov. 16, 2014, which is the above claimed priority application, is herein incorporated in this application by reference. The following detailed description is of the best currently contemplated modes of carrying out exemplary embodiments of the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention, since the scope of the invention is best defined by the appended claims. Various inventive features are described below that can each be used independently of one another or in combination with other features. 
         [0029]    Referring to  FIG. 1 , a vacuum cup assembly  10  may include a housing  12  having a chamber  14  that may be defined by a wall  16 . The wall  16  may be cylindrical, which includes at least circular cylindrical, square cylindrical, or any other cylindrical shape, and may have one or more walls forming the housing  12 . Alternatively, the housing may have a planar wall, such as a plate (see  FIG. 7 ). The housing  12  may have a wall  34  at a first side to which a prime mover, which may be an electrical motor, a solenoid  20  or any other device that imparts rotary or linear force, may attach and through which a linkage  24  may extend to drivingly link the solenoid  20  to a piston  22 . The electric motor or solenoid  20  may include connection to an AC or DC electrical source if they are electrically powered, and the source may be mounted to the housing  12 . The electric motor may be rotary or linear, and the solenoid may be rotary or linear. 
         [0030]    The piston  22  may be sealingly mounted in the chamber  14 , such as by a close-tolerance fit to the sidewall&#39;s radially inwardly-facing surface, and the piston  22  may include a seal  30 , such as an O-ring or other gas-sealing structure, at the radially outwardly-facing peripheral edge of the piston  22 . The piston  22  thus forms a sidewall defining at least a portion of a variable volume chamber between the piston  22  and the housing  12 , which variable volume chamber is described in more detail below. 
         [0031]    The housing  12  may have a wall, which may be the base  36 , through which a housing aperture  38  is formed on the housing  12  opposite the wall  34 . A piece of tubing  26  may be connected to, or inserted through, the housing aperture  38  and a vacuum cup  28  may be attached to the tubing  26  via a cup aperture  40 . The cup aperture  40  may be at the top of the vacuum cup  28 , for example, in the orientation shown in  FIG. 1 . The cup aperture  40  may, alternatively, be located at the walls  42  of the vacuum cup  28 , and may include a plurality of apertures. 
         [0032]    The tubing  26  may be inserted through the aperture  38 , and may extend a significant distance between the vacuum cup  28  and the base  36 . If the tubing  26  is rigid enough, the tubing  26  functions as an extension of the housing  12 , thereby extending the vacuum cup  28  into, for example, a hollow work piece such as a box, to enable the box to be picked up from the bottom floor. 
         [0033]    The linkage  24  may be a rigid rod, a threaded shaft (e.g., a screw), or a rack and pinion, connecting the solenoid  20  to the piston  22 , depending upon the manner in which the solenoid imparts force to the piston  22 . The linkage  24  preferably connects the solenoid  20  to the piston  22  to permit the solenoid  20  to move the piston  22  in one or more strokes within the bore of the housing  12 . The linkage  24  may include a spring that biases the piston  22  toward the top of the chamber  14  closer to the solenoid  20 , or that biases the piston  22  toward the bottom of the chamber farther away from the solenoid  20 . Upon moving the piston  22  upwardly from the position shown in  FIG. 1 , a space is formed between the piston  22  and the base  36  that is part of the variable volume chamber within the housing  12 . The solenoid  20  may, during typical operation, displace the piston  22  in one direction, there may be a pause of a fraction of a section to minutes, and then the solenoid  20  may displace the piston  22  in the opposite direction. Alternatively, the solenoid  20  may displace the piston  22  reciprocatingly without substantial pause at the end of each stroke or each cycle. This will become apparent to the person of ordinary skill from the description herein. 
         [0034]    The vacuum cup  28  is preferably a conventional flexible vacuum cup having a lower rim that initially seats against an object that is to be lifted, and walls  42  that are sufficiently flexible to permit deformation thereof as lower pressure is created within the variable volume chamber  14 ′. The vacuum cup  28  may form a temporary mechanical attachment to a work piece, thereby allowing the vacuum cup  28  to readily pick up a work piece at one location and move the work piece to another location, whereupon the vacuum cup  28  releases the work piece as described herein. In the embodiment of  FIG. 1 , the workpiece is mechanically attached by displacing the piston  22  upwardly in the orientation of  FIG. 1 , and then released by displacing the piston  22  downwardly. The vacuum cup  28  may be made of silicone, rubber, latex or other polymers as an example, so that the body of the vacuum cup  28  is flexible, yet sturdy enough to hold up a work piece for a period of time. 
         [0035]    In operation, the electric motor or solenoid  20  is powered on and the piston  22  may be lifted up in the chamber  14  to enlarge the variable volume chamber  14 ′ that is within the housing  12  between the piston  22 , which serves as a sidewall to the variable volume chamber  14 ′, and the base  36 , which is a wall of the housing  12 . This enlargement decreases pressure in the variable volume chamber  14 ′, and this lower pressure draws fluid from the housing aperture  38 , the bore of the tubing  26 , and the cavity of the vacuum cup  28 . If the rim of the vacuum cup  28  is seated against a work piece surface, the lower pressure in the cavity of the vacuum cup  28  relative to the atmosphere outside of the assembly  10  causes the rim of the cup  28  to seal against the workpiece surface. Further reduction in pressure in the variable volume chamber  14 ′ may cause the walls  42  to deform outwardly and upwardly, thereby causing the interiors of the walls  42  to seat against the surface of the work piece. Thus, the relatively negative pressure in the vacuum cup  28 , when the lower rim of the cup  28  contacts a surface of the work piece, causes the lower rim of the cup  28  to create a suction force against the work piece. As the piston  22  is moved upwardly further, the pressure in the vacuum cup  28  cavity is further reduced to generate a temporary attachment force sufficient to pick up the work piece. The work piece is thus picked up, acted upon, such as by moving the work piece, and, upon de-activation of the solenoid  20  or reversal thereof, the negative pressure may be relieved and the work piece may be released. The negative pressure is relieved in the embodiment of  FIG. 1  by displacing the piston  22  downwardly in the orientation of  FIG. 1 . Thus, by controlling the prime mover that may be powered by a power source contained on or within the assembly  10 , the vacuum cup assembly  10  enables a user to pick up and release a work piece with precision and control and without the disadvantages of the prior art. 
         [0036]    Described herein is an improved vacuum cup assembly having a vacuum cup  28  with a wall terminating at a lower end in a rim. The rim is configured to seat against the work piece for forming a temporary attachment to the work piece, and a concave fluid chamber is defined within the vacuum cup  28  sidewall. The vacuum cup is mounted to the housing  12 , and the housing  12  at least partially defines a variable volume chamber that is fluidically connected to the concave fluid chamber in the vacuum cup  28 . A sidewall, which may be a piston  22 , is moveably mounted to the housing  12  and partially defines the variable volume chamber. The prime mover, which may be the solenoid  20 , is mounted to the housing  12  and the piston  22 , and the solenoid  20  is selectively moveable to displace the piston  22  relative to the housing  12 , thereby modifying the volume of the variable volume chamber and modifying the fluid pressure in the concave fluid chamber. 
         [0037]    As shown in the alternative cup assembly  110  of  FIG. 2 , the piston  122  may have a valve  144  disposed between the cup  128  and the chamber  114  within the housing  112 . The valve  144  may be actuated manually or automatically in order to vent air or other gases into or out of the variable volume chamber  114 ′ that is between the piston  122  and the base  136  of the housing  112 . The valve  144  may be a one-way or “check” valve that permits gas to flow in one direction, such as out of the variable volume chamber  114 ′, but not in the opposite direction. Alternatively, the valve  144  may be a selectively-actuated valve that may be controlled by a computer to open and close. The valve  144  enables the cup assembly  110  to generate a continuous suction at the vacuum cup if the lower rim is not sealingly seated against a surface of a work piece by to pump large volumes of gas out of the cup  128  by cyclical reciprocation of the piston  122  resulting from continuous actuation of the solenoid  120 . Thus, the solenoid  120  may displace the linkage  124  in one direction to displace the piston  122  away from the vacuum cup  128 , and then displace the linkage  124  in the opposite direction to displace the piston  122  toward the vacuum cup  128 , and repeat this cyclically. When operating as a one-way valve out of the variable volume chamber  114 ′, the valve  144  permits rapid, cyclical movement of the piston  122  to eject the gas drawn into the variable volume chamber  114 ′ into the portion of the chamber  114  that does not include the variable volume chamber  114 ′, and this portion may be vented to the atmosphere. Thus, the cup assembly  110  may be able to continuously operate the solenoid  120  until the rim of the cup  128  seals against a work piece surface and attaching temporarily thereto. At that point, the solenoid  120  can be paused, or it can continue reciprocating if sufficient additional valves are in place. 
         [0038]    In another cup assembly  710  shown in  FIG. 8 , in addition to the valve  754 , which is equivalent to the valve  144  of  FIG. 2 , the housing  712  may have one or more valves  756  and  758  disposed in the wall  716  of the housing  712 . The valves  754 - 758  may allow for air or another gas to move into or out of the spaces, such as the variable volume chamber  714 ′, which are fluidically connected by passages that the valves  754 ,  756  and  758  may selectively block or open. The valves  754 ,  756  and  758  may be one-way valves that permit passage of gas in only one direction. Alternatively, the valves  754 ,  756  and  758  may be electronically controlled by a computer to permit gas to flow, selectively, in one or both directions. The valves  754 ,  756  and  758  may be used to release a relatively low pressure, at times referred to herein as a “vacuum”, from a chamber or other portion of the cup assembly  710 . The housing  712  may have one or more sensors (not shown), which may sense a location of the piston  722  or some other structure in the cup assembly  710 , or may sense the pressure in the housing  712 , and those sensors may be connected to send signals to a computer. The valves described herein may be physically isolated from the associated housing and/or sidewall described above, while having the same effect as a valve described and shown herein. Such valves may be, for example, disposed in a tube that fluidically connects to the housing or variable volume chamber, but are remote from the housing or variable volume chamber. Such valves are considered equivalent to those described herein. The term “fluidically connected” is defined herein to mean any connection that permits flow of a fluid (a gas or a liquid). 
         [0039]    As shown in the alternative cup assembly  210  of  FIG. 3 , there may be a diaphragm  246  that serves as a sidewall to the variable volume chamber  214 ′ and displaces fluid in the chamber  214 ′ and fluidically connected cavities. The diaphragm  246  may include one or more valves  244  that may vent air or other gases from the variable volume chamber  214 ′ to or from the chamber  214  or outside the housing  212 . The chamber  214  may be vented to the atmosphere. The valve  244  may have at least one air inlet and may have at least one air exhaust. The valve  244  may be a one-way valve so that air may come through the valve  244  in one direction, such as out of the variable volume chamber  214 ′, or the valve  244  may selectively permit air to pass through in either direction. The air inlet may allow air to move through the diaphragm  246  out of the variable volume chamber  214 ′, and the air exhaust may allow air to vent out of the chamber  214 . The chamber  214  may vent freely with the atmosphere, or another valve may be necessary to permit gas in the chamber  214  to flow out of the assembly  210 . 
         [0040]    The cup assembly  210  of  FIG. 3  has a variable volume chamber  214 ′ that is defined on one side by the base  236  of the housing  212  adjacent to the vacuum cup  228  and the diaphragm  246  that is a flexible membrane extending across the chamber within the housing  212 . Thus, the diaphragm  246  may serve as a sidewall to the variable volume chamber  214 ′ as the piston  22  does in the embodiment of  FIG. 1 . It will be understood that many structures may form a sidewall of the variable volume chamber  214 ′ and may substitute for the diaphragm  246 , including without limitation a bellows or any other flexible membrane that may form a boundary to a variable volume fluid (gas or liquid) chamber. A bellows of sorts is shown and described in the embodiment of  FIG. 7 . Any sidewall that is moveable relative to the housing  212  and modifies the volume of the variable volume chamber  214 ′ that is connected fluidically to the concave fluid chamber  228 ′ in the vacuum cup  228 . 
         [0041]    As shown in the alternative cup assembly  310  of  FIG. 4  there may be a fan  348 , such as a turbo fan, to remove air from the chamber  314 . When the rotary motor  320  that has a driveshaft linkage  324  extending to the fan  348  is turned on, a negative pressure relative to atmospheric pressure outside of the assembly  310  may be created inside the vacuum cup  328  so that the vacuum cup  328  may have sufficient suction force to pick up a work piece. 
         [0042]    As shown in the alternative cup assembly  410  of  FIG. 5 , the electric motor  420  may be connected to the piston  422  via a driveshaft with an offset cam  424 . The motor  420  may be mounted to the wall of the housing  412  and be adjacent the base  436  to which the vacuum cup  428  mounts. When the electric motor  420  is powered on, the cam  424  may be rotated, thereby causing the piston  422  to be displaced up and then down (in the orientation of  FIG. 5 ) in the housing  412 , depending upon the angle of rotation of the driveshaft. Moving the piston  422  upwardly enlarges the variable volume chamber  414 ′ and draws fluid into the chamber  428 ′ of the vacuum cup  428  and into the variable volume chamber  414 ′, thereby creating suction and the temporary attachment of a work piece. Moving the piston  422  downwardly reduces the volume of the variable volume chamber  414 ′ and forces fluid out of the variable volume chamber  414 ′ into the chamber  428 ′ of the vacuum cup  428 , thereby releasing the work piece. 
         [0043]    Continuous rotation of the driveshaft causes the piston  422  to reciprocate within the housing  412 , which would simply pump fluid into and out of the variable volume valve  414 ′ in the embodiment of  FIG. 5 . In such a situation, a valve system like that shown in  FIG. 2  or  FIG. 8  would cause such a piston  422  to draw fluid continuously into the chamber  428 ′, then into the chamber  414 ′, and then ventilate the variable volume chamber  414 ′ into the atmosphere. The  FIG. 8  embodiment is essentially the  FIG. 5  embodiment with the addition of one or more valves. 
         [0044]    As shown in  FIG. 6 , a linkage  524  may be formed between an electric motor  520  and a diaphragm  546 , or any other sidewall to the variable volume chamber  514 ′. The linkage  524  may be a lever and a rod  550 . There may be a slip clutch or other force-limiting structure between the motor  520  and the linkage  524 . The slip clutch may be used to limit the torque applied to the linkage  524 . In operation, when the electric motor  520  is turned on, the linkage  524  may pivot around an axis of the axle  552  as a circle. In turn, the diaphragm  546  may be displaced upwardly in the orientation of  FIG. 6  to displace air in the chamber  514 ′, thereby drawing fluid into the vacuum cup  528  due to negative pressure compared to the atmospheric air pressure. This creates sufficient suction force for the vacuum cup  528  to pick up a work piece. The linkage  524  may be replaced by a pulley, and the rod  550  may be replaced by a string, cable, chain, or belt, for example. In operation of such an alternative, when the motor  520  is turned on, the pulley winds up the cable, thus pulling the piston or diaphragm  546  and enlarging the variable volume chamber  514 ′. It is contemplated that the motor  520  may be a rotary solenoid. 
         [0045]    Referring to  FIG. 7 , a vacuum cup assembly  610  may include a housing  612 , which consists of a plate  636  to which a frame member  602  is mounted, thereby forming a chamber  614  that is open to the atmosphere. An electrical motor or solenoid  620  mounts to the housing  612  via the frame member  602 , to drive a diaphragm  646 . The housing  612  may have a base  636  and a housing aperture  638  in the base  636 , and the motor or solenoid  620  may be mounted to the base  636 , the frame member  602  or any other solid structure. Thus, the motor or solenoid  620  is not limited in where it can be positioned. A tubing  626  and a vacuum cup  628  with a cup aperture  640  may be connected to the housing  612  at the housing aperture  638 . The cup aperture  640  may be at the top, in the orientation of  FIG. 7 , of the vacuum cup  628 . The cup aperture  640  may alternatively be disposed in the wall  642  of the vacuum cup  628 . 
         [0046]    The vacuum cup assembly  10  may further include a linkage  624 , such as a threaded shaft, a rigid rod, or a rack and pinion, connecting the electric motor or solenoid  620  to the diaphragm  646 . The linkage  624  may include a spring that urges the diaphragm  646  downwardly or upwardly in the orientation of  FIG. 7 . The solenoid  620  may include an electric connector  632  electrically connected to an AC or DC electrical source, which may be located on the assembly  610 . The vacuum cup  628  may have a deformable, flexible wall  642  that permits the vacuum cup  628  to readily pick up a work piece at one location and move the work piece to another location. The vacuum cup  628  may be made of silicone, rubber, or polymers, for example, so that the body of the vacuum cup  628  is flexible, yet sturdy to hold up a work piece for a period of time. 
         [0047]    In operation, the electric motor or solenoid  620  is powered on and the diaphragm  646  may be moved downwardly to displace air in the variable volume chamber  614 ′ that is defined by the housing  612  and the diaphragm  646 . The solenoid  620  may then displace the diaphragm  646  upwardly to create negative pressure in the vacuum cup  628  relative to atmospheric pressure. Because the negative pressure exists in the vacuum cup  628 , the lower rim of the vacuum cup  628  may create a suction force sufficient to pick up a work piece. Valves like those shown in  FIGS. 2, 3 and 8  may be mounted in the diaphragm  646 , the housing  612  or elsewhere to selectively ventilate the variable volume chamber  614 ′ to the atmosphere to release a work piece. The valves may be controlled by a computer to selectively permit the passage of air into the variable volume chamber  614 ′ or out of the variable volume chamber  614 ′. 
         [0048]    As shown in the alternative cup assembly  710  of  FIG. 8 , the electric motor  720  may be connected to the piston  722  via a driveshaft with an offset cam  724 . When the electric motor  720  is powered on, the cam  724  may be rotated causing the piston  722  to be displaced up and then down (in the orientation of  FIG. 8 ) in the housing  712 , depending upon the angle of rotation of the driveshaft. Moving the piston  722  upwardly enlarges the variable volume chamber  714 ′ and draws fluid into the chamber  728 ′ of the vacuum cup  728 , which creates suction at the vacuum cup  728 , and moving the piston  722  downwardly releases the work piece. Continuous rotation of the driveshaft causes the piston  722  to reciprocate up and down cyclically within the housing  712 , and the valves  754 ,  756  and  758  shown in  FIG. 8  cause fluid to be drawn continuously into the chamber  728 ′ and into the variable volume chamber  714 ′. The series of valves  754 ,  756  and  758  may permit gas to flow into the variable volume chamber  714 ′ during piston  722  reciprocation, and prevent gas from moving out of the variable volume chamber  714 ′ through the valves  754 ,  756  and  758 . Alternatively, the valves  754 ,  756  and  758  may be computer-actuated to open and close. The motor  720  may be operated at all times during use of the assembly  710  and gas will flow from the chamber  728 ′ in the vacuum cup  728  into the variable volume chamber  714 ′. One or more of the valves  754 ,  756  and  758  may be manually or automatically (such as by a computer controlling operation according to a computer program) operated to permit gas flow in the opposite direction at some times in order that little to no suction is generated in the vacuum cup  728 . This may be desirable for continuous operation of the motor  720  to generate suction at only times when the more readily controlled valves  754 ,  756  and  758  are configured to permit such suction. In this way, the valves  754 ,  756  and  758  may permit regulation of suction on the assembly  710 , rather than using the operation of the motor  720  to regulate suction. By controlling one or more of the valves  754 ,  756  and  758 , this may allow one to attempt to attach to a work piece multiple times, because while the motor  720  continues to rotate the valves  754 ,  756  and  758  may be controlled to control the flow of gas and provide continuous suction through the cup  728  and prevent damage to the work piece or any other structure. The invention thus permits one to pick up a porous work piece by continuously drawing gas that is pulled through the porous work piece. 
         [0049]    As shown in the alternative cup assembly  810  of  FIG. 9 , the electric motor  820  may be connected to the piston  822  via a driveshaft with an offset cam  824 . When the electric motor  820  is powered on, the cam  824  may be rotated causing the piston  822  to be displaced up and then down (in the orientation of  FIG. 9 ) in the housing  812 , depending upon the angle of rotation of the driveshaft. Moving the piston  822  upwardly enlarges the variable volume chamber and draws fluid into the chamber of the vacuum cup  828 , which creates suction at the vacuum cup  828 , and moving the piston  822  downwardly releases the work piece. It should be noted that selective actuation of the valve  856  in the passage  850  also releases the work piece by ventilating the negative pressure in the vacuum cup  828 . 
         [0050]    It is contemplated that the housing of any of the embodiments herein described could be extended by a tube that mounts to the housing near the variable volume chamber and extends to the vacuum cup. This may be desirable in the case of a suction cup that will temporarily mount to the inside of a workpiece, such as a box or can, which has sidewalls that prevent attachment without the extension of the housing that the tube is. 
         [0051]    It should be understood, of course, that the foregoing relate to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims. 
         [0052]    This detailed description in connection with the drawings is intended principally as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention and that various modifications may be adopted without departing from the invention or scope of the following claims.