Abstract:
A multi-stage pressure/vacuum apparatus is disclosed for a bi-directional pneumatic delivery system or the like. The apparatus includes separated turbines or separated sets of turbines that are operated independently of each other to alternatively create pressure and vacuum conditions for an external system such as a pneumatic delivery network relying upon the inventive apparatus for pressure and/or vacuum generation. A common housing contains both turbine sets and defines a system of internal chambers and valve mechanisms between them. The valve mechanisms respond to internal pressures created within the housing by the turbines, and preferably also to gravity in order to control air flow patterns through the housing and between the housing and an external system. According to the present invention, the turbines of the two turbine sets can be operated concurrently at maximum capacity or separately if air power requirements are lesser. The present invention also contemplates a method of creating pressure or vacuum conditions with the inventive apparatus disclosed. The present invention further contemplates a bi-directional pneumatic delivery system including the multi-stage pressure apparatus disclosed.

Description:
This application claims the benefit of earlier filed U.S. provisional application No. 60/335,793 filed Dec. 5, 2001 under 35 U.S.C. §119(e). 

   BACKGROUND OF THE INVENTION 
   The present invention relates to a multi-stage pressure apparatus ideally suited for creating pressure and vacuum conditions in a bi-directional pneumatic conveyance system such as the one generally disclosed in U.S. Pat. No. 5,562,367, the disclosure of which is incorporated herein in its entirety. More particularly, the present invention relates to a multi-stage pressure apparatus including independently operable pressure generation units and internal chambers and valve mechanisms to selectively create pressure or vacuum conditions in response to mere activation of the pressure generation units. The present invention also relates to a method of pressure or vacuum generation with such a multi-stage apparatus, and an actual bi-directional pneumatic conveyance system incorporating such an apparatus. 
   SUMMARY OF THE INVENTION 
   The present invention provides a simplified apparatus ideally suited for pressure and/or vacuum generation in a system such as a bi-directional pneumatic conveyor. Indeed, the present invention contemplates a bi-directional pneumatic conveyance system including the inventive multi-stage air pressure generator disclosed herein. The multi-stage air pressure apparatus according to the invention can be contained in a generally rectangular outer housing for relative ease in manufacturing and subsequent maintenance. The pressure generation apparatus is described as “multi-stage” because it generates maximum pressure in stages (two stages according to the preferred embodiment), and also maximum vacuum conditions in stages (three stages in the preferred embodiment). 
   The multi-stage pressure apparatus includes a housing with internal chambers and ports between a first turbine chamber that contains at least one turbine and a second turbine chamber than contains at least one other turbine. The turbines of each chamber can be activated independently of each other, at slightly different times. The chambers and their ports within the housing selectively are opened and closed by valve elements that respond to pressures created within the chambers by the turbines, and in the preferred embodiments, that also respond to gravity. The valve elements include biased valves, unbiased valves and, in the preferred embodiment, particularly configured spool valves. 
   Within the housing, a common pressure chamber selectively can be placed in communication with either or both of the turbine chambers to conduct pressurized air from the discharge or pressure side of the turbines. The common pressure chamber also selectively can be placed in communication with either an external connection chamber adapted for interface with an external system such as a bi-directional pneumatic conveyor, or an intake/exhaust chamber that is in communication with the outside atmosphere through an intake/exhaust port. 
   In the preferred embodiment of the present invention, mere activation of the turbines according to predetermined sequences, and the affect of gravity on certain of the valve elements, controls whether the multi-stage pressure apparatus will create pressure or vacuum conditions at the external connection chamber and hence in an interfaced external system. Indeed, according to the preferred embodiment, it merely is a matter of whether the turbine or turbines on one side of the common pressure chamber or the turbine or turbines on the other side of the common pressure chamber is/are activated first. Maximum vacuum and pressure conditions are created when all turbines are active. If for some reason, however, less than maximum pressure or vacuum conditions are desired, the apparatus can be operated with less than all turbines active. 
   During multi-stage vacuum generation, two different and distinct air flow paths or patterns are formed within the apparatus housing. Air intake for activated turbines on one side of the common pressure chamber initially is provided by an intake/exhaust port that is in permanent communication with the outside atmosphere. In the first vacuum creation stage, there is no movement of air from out of the common pressure chamber and so a relatively large pressure builds therein. This pressure build-up changes the position of certain valve elements that are responsive to pressure in order to automatically reconfigure the apparatus internally so that intake air for the active turbines begins to be drawn in from external of the apparatus through the external connection chamber, and at the same time, the intake/exhaust port instead begins to vent air discharged from the active turbines. Establishment of this first flow path from the external connection chamber to the intake/exhaust chamber now serving as a vent for outgoing air, creates vacuum conditions at the external connection chamber. Once this first vacuum flow path becomes established, the turbines on the other side of the common pressure chamber can be activated to provide a second air flow pattern that merges with the first to thereby maximize vacuum conditions the exhaust connection chamber and therefore the interfaced external system. 
   Pressure generation by the inventive multi-stage apparatus is simpler than vacuum generation and involves a first air flow path from the intake/exhaust chamber to activated turbines, through the common pressure chamber and out through the external connection chamber. In the case of pressure generation, turbines other than the one activated to initiate vacuum creation are activated. Once a first pressure flow path has been established by the active turbines, the other side turbine or turbines can be activated to increase air flow from the intake/exhaust chamber to the external connection chamber to correspondingly increase (maximize) the pressure at the external connection chamber. 
   It will be appreciated that multiple capacities accomplished by the present apparatus allow the apparatus to function effectively and efficiently when it is utilized with different item carrier networks or the like in different environments. For example, when the inventive multi-stage apparatus operates to supply air in a large tube network, as say in a bank teller network, pressure losses may be greater than for a less complicated or smaller network. In the former case, a relatively larger pressure supply capacity might be required. By contrast, in the latter case, the present invention may supply air using a pressure stage which generates pressure at a smaller capacity to more efficiently supply the pressure needs of a particular tube network. In addition to networks of different sizes, some item conveyance tasks or sets of tasks might require more or less pressure or vacuum supply capacity. For example, a tube network may require one pressure level for conveyance to cash registers at the front of, for example, a warehouse. A different supply may be necessary to adequately supply pressurized air to transport an item between different parts of the warehouse. The present apparatus&#39; unique capabilities may be controlled to most efficiently accomplish varied operational requirements. 
   Furthermore, maintenance on the multi-stage apparatus according to the present invention can be simplified. This is because, for example, in the preferred embodiment, the valve elements which regulate air flow between the chambers are responsive simply to internal pressures and gravity. Hence, the preferred embodiment calls for check valves that are weighted or otherwise biased appropriately to open only after a certain internal pressure overcomes the bias weight. Likewise, the preferred embodiment calls for spool valves that move to open or close chambers and control appropriate flow paths when internal pressures and/or gravity act on the spool valves. The inventive apparatus, in its simplest form, then, has no need for a more complicated control system, for example, to sense internal pressures electronically for instance, and then control the position of the valve elements accordingly. Because the valve elements can be actuated simply by pressure or gravity, such elements can be relatively uncomplicated weighted and/or hinged elements. As a result, maintenance is much easier due to the presence of simple mechanical elements. One of ordinary skill, however, would find it obvious to substitute more complicated elements such as pneumatic/electronic control valves, if desired. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further aspects and features of the present invention will be even more apparent from the detailed description and drawings, and the appended claims. In the drawings: 
       FIG. 1  is a schematic diagram of a bank teller carrier system incorporating the multi-stage pressure supply apparatus of the present invention; 
       FIG. 2  is a schematic side view focusing on interior structure and operation of a preferred embodiment of the multi-stage pressure supply apparatus of the present invention, in a first pressurization stage; 
       FIG. 3  is a schematic side view, similar to  FIG. 2 , of the multi-stage pressure supply apparatus in a second pressurization stage; 
       FIG. 4  is a schematic side view, similar to  FIG. 2 , of the multi-stage pressure supply apparatus in a first vacuum forming stage; 
       FIG. 5  is a schematic side view, similar to  FIG. 2 , of the multi-stage pressure supply apparatus in a second vacuum forming stage; and 
       FIG. 6  is a schematic side view, similar to  FIG. 2 , of the multi-stage pressure supply apparatus in a third vacuum forming stage. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1  schematically depicts a bi-directional pneumatic transportation system  100  in which the multi-stage pressure apparatus  10  according to the present invention is incorporated. Pneumatic transportation system  100  ideally is suited for use in the form of a bank teller network including, for example, a teller station  112 , typically within the bank and a customer station  114  remote from the bank main building. Communication between the teller and customer is provided by a carrier  116  depicted as transported by pressure and vacuum conditions created within a carrier tube network  118 . Carrier  116  is transported between respective carrier reception areas  120  at the teller station  112  and  122  at the customer station  114 . While multi-stage pressure apparatus  10  is disclosed as providing the vacuum and/or pressure engine for system  100 , it should be considered that apparatus  10  can have application in any like application requiring controlled pneumatic pressure and vacuum creation. 
     FIGS. 2–6  show the same schematic, cut-away side view of apparatus  10  and include arrows demonstrating air flow patterns through the apparatus to create pressure and vacuum conditions within an interfaced external network such as carrier tube network  118  shown in  FIG. 1 . Specifically,  FIGS. 2 and 3  demonstrate two stages of pressure creation by apparatus  10 , while  FIGS. 4–6  show three stages of vacuum creation. Reference now will be made to  FIG. 2  in detail to discuss the elements and assemblies of apparatus  10 , while explaining first stage pressure generation at length. 
   Apparatus  10  has a generally rectangular housing  11  that defines an external connection chamber  12  adapted to interface with a tube network or the like to be supplied with pressurized air. External connection chamber  12  is shown with a pressure hose connector port  14  and a vacuum hose connector port  16 . Pressure hose port  14  is closeable by a vacuum check valve  18 , and similarly, vacuum hose connector port  16  is sealable by a pressure check valve  20 . As understood from the preferred implementation of apparatus  10 , in the absence of internally or externally generated pressure conditions, vacuum check valve  18  simply will close due to gravity while pressure check valve  20  will open under force of gravity. As apparent to those of ordinary skill, alternative valve devices controlled not merely in response to pressure and gravity freely could be substituted for check valves  18  and  20 . 
   On the left-hand side of  FIG. 2 , housing  11  contains a first turbine pair labelled A and on the right-hand side, a second turbine pair labelled B. Specifically, the turbine pairs A and B, respectively, are housed in a first or A-side turbine chamber  21  and a second or B-side turbine chamber  23 . For purposes of discussion, turbine chambers  21 ,  23  are divided internally such that it will be said that vacuum intake chamber  30  is located above turbine pair A and vacuum intake chamber  32  is located above turbine pair B. The turbines of pair A and pair B discharge into a pressure chamber  36  and a pressure chamber  38  that respectively form the lower portion of each of turbine chambers  21  and  23 . Intake chambers  30 ,  32  are configured to be in permanent communication with each other, and selectively placed in communication with an intake/exhaust chamber  33  having an intake/exhaust port  34  during different stages of operation. Port  34  is in permanent communication with the outside atmosphere. Preferably, each of turbine pair A and turbine pair B has at least one turbine with two turbines being shown in each turbine chamber  21 ,  23  in the Figures. As will be appreciated, more or less turbines can be included in turbine set/pair A and turbine set/pair B. Also, it will become clear that, depending on how the various valve elements are biased, it may not be necessary to have the same number of turbines on each side of common pressure chamber  50 , or alternatively, turbines of different air movement capability. Further, it will be apparent to those of ordinary skill that various types of air driving apparatus can be used in place of the turbines called for in the disclosed embodiment. 
   Apparatus  10  features a common pressure chamber  50  intermediate between the turbine pairs that selectively receives air discharged from the turbines through either or both of turbine pressure chambers  36  and  38 . Apparatus  10  employs an unbiased (in the preferred embodiment unweighted) check valve  52  to selectively isolate turbine pressure chamber  36  from the common pressure chamber  50  through a port  37 . On the other hand, a biased, herein weighted, check valve  54  selectively opens or closes communication between turbine pressure chamber  38  and common pressure chamber  50  through a port  39 . While the bias for valve  54  derives from weight and gravity in the preferred embodiment, it is contemplated that such could be created by other mechanical or electrical-mechanical means as well. Also, while valve  52  is depicted as disposed to be oriented primarily vertically when closed over port  37 , and valve  54  is depicted as disposed to be oriented primarily horizontally when closed over port  39 , other arrangements for the valves will be apparent. 
   Housing  11  also defines a valve connection chamber  60  regulated by two spool valves  62  and  64  that each have respective upper and lower operational positions. Vacuum spool valve  62  has disks  66  and  68 . Disk  68  toggles between two ports  70  and  72  of intake/exhaust chamber  33 , while disk  66  toggles between closure of a port  74  and a removed upper position. When not closed by disk  66 , port  74  puts the external connection chamber  12  in communication with the intake/exhaust chamber  33  as well as each of connected turbine vacuum chambers  30 ,  32 . Differential spool valve  64 , on the other hand, has closure disks  80  and  82  wherein disk  82  toggles to selectively close a port  84  between turbine pressure chamber  38  and the common pressure chamber  50 , and wherein disk  80  toggles between ports  86  and  88  to open or close these ports. Ports  86  and  88  can be regarded as exit ports from the common pressure chamber  50  in that they lead to valve connection chamber  60  and external connection chamber  12 , respectively. It is to be understood that port  88  actually leads into a tubular structure  89  connecting common pressure chamber  50  with external connection chamber  12 . Tube  89  is sized so as to not prevent communication between turbine vacuum chambers  30 ,  32 . 
   As seen, the lower portion of differential spool valve  64  is received in a cylindrical assembly  90  that, in turn, is located within the B-side turbine pressure chamber  38 . Assembly  90  guides disk  82  as valve  64  moves between port  84  at the upper portion of the assembly and back. An upper flexible seal disk  100  is disposed around spool valve  64  and seals spool valve  64  against the exterior valve seat walls between common pressure chamber  50  and valve connection chamber  60 . This prevents pressure leakage into the valve connection chamber  60 . when the common pressure chamber becomes pressurized. Similarly, a lower flexible seal disk  102  is disposed around spool valve  64  and seals the spool against the valve seat walls above assembly  90  to prevent leakage from common chamber  50 , when pressurized, into turbine chamber  38 . 
   Operation of apparatus  10  and specifically the air flow process through the five distinct stages of the apparatus of the present invention now will be described.  FIGS. 2 and 3  together show a two-stage pressurization procedure. We begin the operation description with primary reference again to  FIG. 2 . The early stage of the pressurization process is illustrated in  FIG. 2  when the turbines of turbine pair A are activated. Turbines A draw in intake air indicated by arrow I from intake/exhaust port  34 , through intake/exhaust chamber  33 , and through turbine vacuum chamber  30  into the air intake side of each turbine. Turbine pressure chamber  36  becomes pressurized by air discharged by the activated turbine pair A. Pressure force in chamber  36  opens unweighted check valve  52  and communication with common pressure chamber  50  through port  37  whereupon air flow pattern I is established through the common pressure chamber and the connection tube  89 , into external connection chamber  12 . 
   Increased pressure in connection chamber  12  opens vacuum check valve  18  while holding pressure check valve  20  closed. Increased pressure in common pressure chamber  50  meanwhile upwardly forces seal disk  100  against the interior walls of the common pressure chamber to form the seal ensuring isolation between valve connection chamber  60  and the common pressure chamber. Likewise, high pressure forces seal disk  102  downwardly over port  84  to form a seal isolating assembly  90  from the common pressure chamber  50 . Sealing occurs as disks  100  and  102  flex under pressure force as air flow I continues through common pressure chamber  50 , and through port  88  into external connection chamber  12  to exit at port  14 . 
   On the other hand, there is no passage for air flow into valve connection chamber  60  from common pressure chamber  50 . This is because high pressure in chamber  50  also exerts downward force on differential spool valve disk  80  to hold the disk over port  86 . Air pressure created in external connection chamber  12  due to flow I forces pressure check valve  20  closed as mentioned above, but also at the same time, forces disk  66  of vacuum spool valve  62  downwardly over port  74 . This prevents pressure escape through intake/exhaust port  34 . In the configuration described, common pressure chamber  50  effectively is isolated from vacuum hose connection port  16 , and by turbine pair A, from intake/exhaust port  34 . 
     FIG. 3  illustrates the second pressurization stage after the initial pressure stage described above in connection with  FIG. 2 . The pressurization stage of  FIG. 3  begins by activating at least one of the turbines of set or pair B, preferably about one second after the turbines of pair A have been activated. Turbines B likewise receive intake from intake/exhaust port  34 . The intake air follows a second flow pattern II through open port  72 , around connection tube  89 , into vacuum chamber  32  for the B turbines, to be received by the intake side of the B turbines. 
   Air driven from turbine set B is discharged into pressure chamber  38  where it accumulates while weighted check valve  54  is closed. Immediately, pressurized air accumulating in chamber  38  also begins to act against disk  82  in a direction tending to lift differential spool valve  64 . However, in the preferred embodiment, spool valve  64  will not be lifted by the upward force of turbine B pressure against disk  82  because the pressure of air flow pattern I created by turbine pair A through common pressure chamber  50  exerts downward force against disk  80  in an opposing fashion. As explained above, in preferred apparatus  10 , downward force by turbines A against disk  80  is relatively greater than the upward force by turbines B against disk  82  because the disks are configured so that the surface area diameter of disk  80  is about at least twice the surface area diameter of disk  82 . Thus, pressure created by turbines B increases in chamber  38  until it overcomes weighted valve  54  to open the valve and likewise discharge pressurized air into the common pressure chamber  50  through port  39  to combine with air flow pattern I established by turbines A. This is indicated by air stream III. This combined pressurized air flow passes through port  88 , external chamber  12  and exits at pressure hose connection port  14  to drive, for example, a bi-directional pneumatic item delivery system as discussed above. Operated in this way, apparatus  10  produces a maximum air pressure supply with all turbines (both A-side and B-side) operating. Also, however, it is contemplated here that should less than maximum pressure be needed, less than all turbines could be activated, as desired. What is necessary in the disclosed embodiment is that the A-side turbines (or turbine) be activated first in order to establish air flow pattern I, whereafter the B-side turbines (or turbine) are/is activated to add supplementary air flow pattern II. 
   Description now is made of the three vacuum stages according to the present invention. Reference is made first to  FIG. 4  for the initial vacuum stage. When at rest (turbines inactive), apparatus  10  will be understood to have vacuum check valve  18  falling closed and pressure check valve  20  falling open. When apparatus  10  is to generate vacuum conditions in a hose or the like interfaced at vacuum connector port  16 , turbines B are started first. At this time, the B turbines draw in air from intake/exhaust port  34 . Intake air, identified by arrow I′, flows through port  72 , around connection tube  89 , into the B-side vacuum chamber  32 , and to the intake of the B turbines. The B turbines likewise discharge into pressure chamber  38  and so pressure in chamber  38  acts with upward tending force on check valve  54 . However, preferred check valve  54  is weighted so that it will not open at this stage. Instead, the pressure building in chamber  38  now exerts sufficient upward force upon disk  82  to raise differential spool valve  64  to the spool valve&#39;s upper position. In this position, spool valve disk  82  closes over port  84  and spool valve disk  80  closes off port  88  and opens port  86  below. Unlike the pressurization stages, during this first vacuum stage there is no pre-existing turbine-generated high pressure in common pressure chamber  50  to act against larger diameter disk  80  and resist upward movement of differential valve  64 . In preferred apparatus  10 , therefore, spool valve  64  and check valve  54  are weighted such that during this first vacuum stage, pressure created in chamber  38  by the B-side turbines will lift spool valve  64  before it will be sufficient to open weighted check valve  54 . With differential spool valve  64  in its upper position and weighted check valve  54  closed, air cannot yet escape from pressure chamber  38  and accumulates there. This completes the first stage of vacuum creation. 
     FIG. 5  illustrates the second vacuum stage. The increasing pressure in chamber  38  soon overcomes the bias to open check valve  54  and thereby pressurize common pressure chamber  50  through port  39 . At the same time, pressure introduced into chamber  50  holds check valve  52  tight against port  37  to hold this port closed. Closing of check valve  52  ensures that pressure created by turbines B will not enter A-side pressure chamber  36  and cause reverse turbine rotation and/or over current conditions at the time the A-side turbines are activated. 
   As stated above, when differential valve  64  assumes its upper position, its disk  80  covers port  88 . This blocks air flow from common pressure chamber  50  into connection tube  89  and directs it into valve connection chamber  60  through port  86  where it contacts vacuum spool valve  62 , namely at disk  68  thereof resting over port  70 . Now the pressure introduced into chamber  60  raises vacuum spool valve  62  to open port  70 . As vacuum spool valve  62  is raised to its upper position, note that the air intake for turbines B automatically switches from air drawn in through intake/exhaust port  34  to air drawn in from the vacuum connector port  16  through open pressure check valve  20 . Intake/exhaust port  34  then, at the same time, switches to become the vent for pressurized air entering intake/exhaust chamber  33  from valve connection chamber  60 . Henceforth, air is now sucked in through vacuum connection port  16  to create vacuum conditions in whatever external apparatus is interfaced with that port. This sucked-in air proceeds through port  74 , around connection tube  89  and into vacuum chamber  32 , as the feed I′ for the B turbines. Pressure created in valve connection chamber  60  and intake/exhaust chamber  33  by the air stream I′ rushing out through port  34  holds disk  68  of vacuum spool valve  62  in its upper position away from port  70  and against port  72 . This maintains isolation of chamber  33  from the external connection chamber  12  and turbine vacuum chambers  30 ,  32 . 
     FIG. 6  illustrates the third and final vacuum stage. After a delay of again, preferably about one second, turbine set A is activated to work in combination with turbines B. Intake air for turbines A likewise is drawn in from vacuum connection port  16  through external connection chamber  12 , port  74  and turbine vacuum chamber  30 . Activation of the A turbines pressurizes their chamber  36  and this pressure increases until it overcomes the pressure of air flow pattern I′ established by turbines B through the common chamber  50  to open check valve  52  and establish a second vacuum condition air flow pattern II′. Common pressure chamber  50  now receives the combined pressurized air flow of both of turbine sets A and B. The combined pressurized air flow pattern III′ continues, as in  FIG. 6 , through open port  86 , valve connection chamber  60 , port  70  and out through intake/exhaust port  34  of intake/exhaust chamber  33  to the atmosphere. In this way the capacity of both of turbine sets A and B again can be combined to supply an external item delivery system or the like with a powerful vacuum source by way of port  16 . 
   It is understood that there can be various changes and modifications to the preferred embodiments of the present invention disclosed herein. For instance, alternative valve structures for differential spool valve  64  and vacuum spool valve  62  will be apparent to those of ordinary skill in the art. Likewise, as mentioned earlier in connection with check valves  18  and  20 , alternative valve mechanisms for other check valves disclosed herein such as check valves  52  and  54  will be apparent. However, all such changes and/or modifications which may be made by one of ordinary skill in the art, still would result in an apparatus and composite system well within the scope of the invention as set forth in the claims.