Abstract:
An apparatus for transporting an article through a conduit includes a conduit extending between a sending station and a receiving station, first and second gates remote from the sending and receiving stations for selectively sealing the conduit between a selected one of the gates and the article, a pressure source connected to the conduit between the first and second gates for selectively exhausting or pressurizing the conduit to create a pressure differential across the article in the conduit, a transfer switch connected to the conduit at a predetermined location between the first and second gates, the transfer switch operative to open and close the first and second gates and actuate the pressure source and wherein the conduit between the article and one of the gates is exhausted to propel the article from the sending station toward the transfer switch and the conduit between the carrier and the other of said gates is pressurized in response to a signal from the transfer switch to propel the carrier away from the transfer switch toward the receiving one of the stations.

Description:
TECHNICAL FIELD 
       [0001]    The disclosure and claims presented herein relate to a pneumatic transport system and in particular to a transport system for transporting a carrier between a first station and a second station. 
       BACKGROUND 
       [0002]    Pneumatic transmission systems are widely known and are used to transmit articles through a conduit or tube from a first station to a second station. Many such systems are used in the banking industry to transport documents between remote drive up stations and tellers working in the bank building. Known pneumatic transport systems are described in U.S. Pat. No. 6,592,302 issued Jul. 15, 2003 to Balko, U.S. Pat. No. 6,039,510 issued Mar. 21, 2000 to Greene et al., U.S. Pat. No. 5,584,613 issued Dec. 17, 1996 to Greene et al., U.S. Pat. No. 4,984,939 issued Jan. 15, 1991 to Foreman et al. and U.S. Pat. No. 4,180,354 issued Dec. 25, 1979 to Greene, the disclosures of which are incorporated herein by reference. 
         [0003]    Pneumatic transport systems utilize pressure sources such as blowers or compressors to create a pressure differential across a carrier in the conduit which propels the carrier in the desired direction. The pressure differential may be the result of pressuring the conduit behind the carrier or exhausting the conduit in front of the carrier. If the conduit is pressurized, the conduit in front (direction of travel) of the carrier is open to atmosphere to allow air to escape; if the conduit is exhausted, the conduit behind the carrier is open to atmosphere to allow air to enter the conduit. 
         [0004]    Consequently, known pneumatic systems are provided with a pneumatically sealable door or gate at one or both of the sending and receiving stations. These closed station or closed terminal systems require controls and actuating devices at the stations to operate the gates and limit switches or similar devices to insure that the gates at one or both of the stations are in the correct position. In most instances, known systems also utilize separately controlled pressure or vacuum sources at both ends of the conduit for transport. Known systems also rely on elaborate controls, piping and valving to brake or retard a carrier as it approaches a receiving station to prevent the carrier from impacting the station with sufficient force to damage the carrier and/or the station. Thus, there exists a need for a pneumatic transport system that enables the use of open ended stations or terminals thereby eliminating the use of pneumatically sealable gates at the stations and which provides effective braking of a carrier to avoid damage to the receiving station. 
       SUMMARY 
       [0005]    A pneumatic transport system includes a first station for sending or receiving a carrier, a second station for sending or receiving the carrier and a substantially air tight conduit extending between the first and second stations to convey the carrier between the stations. A transfer switch is operatively connected to the conduit between the first and second stations for generating a signal in response to a carrier passing the switch. The system further includes a first gate for closing the conduit between the first station and the transfer switch, a second gate for closing the conduit between the second station and the transfer switch and a pressure source for selectively exhausting or pressurizing the conduit to create a pressure differential across a carrier in the conduit. A carrier is transported between the stations by exhausting the conduit between the carrier and one of the gates to propel the carrier from the sending station toward the transfer switch. The conduit between the carrier and other of said gates is then pressurized in response to a signal from the transfer switch to propel the carrier away from the transfer switch toward the receiving one of the stations. 
         [0006]    In one aspect, a first deceleration switch is operatively connected to the conduit for generating a signal in response to a carrier passing a predetermined location in the conduit between the first gate and the first station and a second deceleration switch is operatively connected to the conduit for generating a signal in response to a carrier passing a predetermined location in the conduit between the second gate and the second station. When a deceleration switch detects a carrier approaching the receiving station, the gate closest to that station is closed in response to a signal from the switch. Closing the gate reduces the pressure in the conduit between the gate and the carrier, reducing the velocity of the carrier before the carrier reaches the receiving station. 
         [0007]    In another aspect, the first and second gates comprise disk-shaped slide gates configured for rotation into and out of the conduit. A drive unit or actuator is connected to the first and second gates with a mechanical linkage configured to simultaneously rotate the slide gates in opposite directions in response to a signal from the transfer switch. 
         [0008]    The pressure source may be a blower assembly including a single blower and a drive motor for the blower, the assembly being operative in a pressure mode to pressurize the conduit and a vacuum mode to exhaust the conduit. A two way valve may be operatively connected to the transfer switch to switch the blower assembly between the pressure mode and the vacuum mode when a carrier passes the transfer switch. In one embodiment, the pressure source is connected to the conduit adjacent the transfer switch between the first and second gates. 
         [0009]    A method of conveying a carrier from a first station wherein the carrier is inserted into a transport conduit to a second station where the carrier is discharged from the conduit includes the steps of: (a) exhausting the conduit through a port between the carrier and a closed second gate to create sub-atmospheric pressure in the conduit between the carrier and the second gate to propel the carrier through the conduit toward the second station, (b) receiving a signal from a transfer switch connected to the conduit at a predetermined location remote from the first and second stations indicating that the carrier has passed the predetermined location, (c) opening the second gate and closing a first gate between the carrier and the first station in response to the signal from the transfer switch, (d) pressurizing the conduit through the port to create super-atmospheric pressure in the conduit between the carrier and the first gate to propel the carrier through the conduit toward the second station; and (e) receiving the carrier from the conduit at the second station. 
         [0010]    The method may further include receiving a signal from a deceleration switch connected to the conduit between the transfer switch and the second station, indicating that the carrier is approaching the second station. The second gate is closed in response to the signal to reduce the pressure in the conduit between the second gate and the carrier. The reduction in pressure reduces the velocity of the carrier before the carrier reaches the second station. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    For a more complete understanding of the apparatus, system and method disclosed herein, and the advantages thereof, reference is now made to the following description taken in conjunction with the accompanying Drawings in which: 
           [0012]      FIG. 1  is schematic representation of a pneumatic transport system described herein; 
           [0013]      FIG. 2  is a partial schematic representation of a portion of the pneumatic transport system of  FIG. 1 ; 
           [0014]      FIG. 3  is partial end schematic of a pneumatic transport system as described herein; 
           [0015]      FIG. 4  is a partial side schematic of the transport system of  FIG. 3 ; and 
           [0016]      FIG. 5  is a schematic representation of a pressure-vacuum source for use with a pneumatic transport system of the disclosure. 
           [0017]      FIG. 6  is a flow chart illustrating one method of pneumatic transport as described herein; 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    Referring to  FIGS. 1 and 2 , a pneumatic transport system  10  includes first and second stations  12 ,  14 , a substantially air tight conduit  16  extending between the stations and a carrier  18  that travels between the stations. Conduit  16  is open to atmosphere at both of stations  12 ,  14 . Carrier  18  includes one or more features such as felt collars at the ends thereof to seal between the carrier and the inside surface of conduit  16  so that a pressure differential can be created across the carrier in the conduit. The user places carrier  18  in station  12  or  14  which results in the top of the carrier being positioned in conduit  16  sufficient to be drawn into the conduit completely under sub-atmospheric pressure. 
         [0019]    Signals from “SEND” switches on stations  12  and  14  are used to initiate operation of the system. Signals from a transfer switch  22 , operatively connected to conduit  16  at a predetermined position between stations  12 ,  14 , are used to control the operation of system  10 . Transfer switch  22  is actuated when a carrier  18  passes the switch when traveling through conduit  16 . In the illustrated embodiment, transfer switch  22  is connected to conduit  16  midway between gates  24 ,  26  and approximately midway between stations  12 ,  14 ; however, it is contemplated that the switch may be connected at other positions along the conduit. 
         [0020]    Transfer switch  22  is operatively connected to a controller  44  that actuates a pair of rotating disk-type slide gates  24 ,  26  positioned in conduit  16  between the transfer switch and stations  12 ,  14 , respectively. Gates  24 ,  26  may be positioned at various locations along conduit  16 , but remote from stations  12 ,  14 . Gates  24 ,  26  are remote from stations  12 ,  14 , in that the gates are positioned away from the stations where the terminal ends of conduit  16  are open to atmosphere. 
         [0021]    In the closed position, gate  24  isolates the section of conduit  16  between that gate and station  14  from station  12 . Similarly, gate  26  may be closed to isolate the section of conduit  16  extending between that gate and station  12  from station  14 . In one embodiment, gates  24 ,  26  are thin plates having a larger disk-shaped first end  28  with a diameter slightly larger than the inside diameter of conduit  16  and a smaller generally triangular end  31  configured for mounting on a rotating operating shaft. In other embodiments, gates  24 ,  26  may be rectangular, oval or some another geometry. In yet other embodiments gates  24 ,  26  may be configured and actuated to move in a linear, rather than rotational, direction to open and close. 
         [0022]    Referring now also to  FIG. 3 , further details of the gate mechanism are illustrated. The gates  24 ,  26  have disk-shaped ends  28  that may be selectively positioned within (as shown in solid line) or out of (as shown in phantom line) the bore of the conduit  16  to separate one portion of the conduit from another. In the illustrated embodiment, the gates  24 ,  26  move within slots  30  (see  FIG. 4 ) formed on either end of the housing  92  by placing a resilient gasket  94  with suitable cut-out section between the housing  92  and end plates  93 . In one embodiment, gates  24 ,  26  are located at positions in conduit  16  adjacent the transfer switch  22 . 
         [0023]    Conduit  16  is pressurized and exhausted through a pressure tube  34  that connects a pressure/vacuum source  36  to the conduit  16  between gates  24 ,  26 . As described below, in one embodiment, pressure/vacuum source  36  may be a single blower assembly including a blower operating in one direction and a two way valve  38 . Alternatively, pressure/vacuum source  36  may be a first blower operating in a pressure mode and a second blower operating in a vacuum mode with associated valves and controls or a single, reversible blower. 
         [0024]    Tube  34  opens into conduit  16  at port  32  adjacent to transfer switch  22 , signals from which control the operation of two way valve  38  to selectively pressurize or exhaust conduit  16  through tube  34 . It is preferred that switch  22  and port  32  be substantially aligned longitudinally within conduit  16 . In the illustrated embodiment, port  32  and transfer switch  22  are connected to conduit  16  midway between gates  24 ,  26 . However, in other embodiments, port  32  and switch  22  may be located closer to one of the gates  24 ,  26  than the other so long as port  32  is positioned between the gates and a distance of not less than one carrier length remains between the port  32  and each of the respective gates  24 ,  26 . 
         [0025]    In one embodiment, pressure/vacuum source  36  is a blower or compressor that may be selectively connected to tube  34  and conduit  16  with valve  38  to pressurize or exhaust selected regions of conduit  16  depending upon the location of carrier  18  in the conduit and the positions of gates  24 ,  26 . In one aspect, gates  24 ,  26  and port  32  are located at positions along conduit  16  such that length and/or volume of conduit  16  between each of the gates and stations  12 ,  14  furthest from each of the gates are approximately equal. 
         [0026]    Referring to  FIGS. 1 and 6 , the transport operation from station  12  to station  14  begins at step  611  with the user placing a carrier  18  into the sending station and initiating the send operation. Gate  26  is closed if not already in the closed position. Controller  44  activates pressure-vacuum source  36  with two way valve  38  in the vacuum position (step  613 ) and gate  24  is opened if not in the open position. The section of conduit  16  between carrier  18  and gate  26  is exhausted, creating a pressure differential across the carrier that propels the carrier through the conduit (step  615 ) toward transfer switch  22 .  FIG. 2  illustrates carrier  18  traveling through conduit  16  as it approaches transfer switch  22 . 
         [0027]    Transfer switch  22  signals controller  44  when carrier  18  passes the switch. (step  617 ). In one embodiment, controller  44  may initiate a short delay, on the order of 0.1 seconds, during which air trapped between carrier  18  and gate  26  is compressed, retarding the motion of the carrier through conduit  16  (step  619 ). After the delay, controller  44  switches two-way valve  38  to the pressurize position (step  621 ), opens gate  26  and closes gate  24 . The section of conduit  16  between gate  24  and carrier  18  is pressurized, propelling the carrier through conduit  16  towards station  14 . 
         [0028]    In many applications, conduit  16  will include vertical sections or legs adjacent stations  12 ,  14 . In these applications, the force of gravity will tend to accelerate carrier  18  as it approaches the receiving station. To counteract the acceleration due to gravity and insure that carrier  18  and/or stations  12 ,  14  are not damaged when the carrier reaches the station, a deceleration switch  40  is connected to conduit  16  between transfer switch  22  and station  14 . Deceleration switch  40  detects carrier  18  traveling toward station  14  and transmits a signal to controller  44  as the carrier passes the switch (step  623 ). 
         [0029]    Controller  44  actuates gate  26 , closing the gate so that pressure in the section of conduit  16  sealed between carrier  18  and gate  26  is reduced as the carrier continues to travel toward station  14  (step  625 ). Alternatively, a solenoid-operated valve or other quick-acting valve may be closed in the blower assembly, effectively sealing the section of conduit  16  to station  14 . In effect, carrier  18  creates a vacuum or sub-atmospheric pressure in conduit  16  between the carrier and gate  26  as it continues to travel through the conduit toward station  14 . The reduced pressure brakes or decreases the velocity of carrier  18  before the carrier reaches station  14 . The velocity of carrier  18  is reduced to prevent damage and wear to the carrier and receiving station  14  when the carrier arrives at the station. 
         [0030]    The send operation is completed with carrier  18  arriving at station  14 , completing the send operation (step  627 ). To send carrier  18  in the reverse direction, the above sequence of steps is repeated with gates  24 ,  26  being operated in the reverse sequence to accomplish the transfer. 
         [0031]    Transfer switch  22  and deceleration switches  40  may be mechanically or pneumatically activated switches, photocells, proximity sensors or any similar switch or sensor that is activated in response to a carrier  18  passing the switch as it travels through conduit. The control functions described above may be accomplished by means of a controller such as a microcontroller, a programmable linear controller, a pre-programmed microprocessor or computer, electromechanical relays, timers and other conventional components generally designated as  44  in  FIG. 1 . 
         [0032]      FIGS. 3 and 4  are schematic representations of an actuating mechanism and linkage for counter-rotational operation of gates  24 ,  26 . In one embodiment, a pair of one-way or single acting solenoids  60 ,  62 , are provided to drive a rocker plate  64  that rotates around a pivot  66  positioned midway along and laterally offset from a central longitudinal axis of the plate. It will be appreciated that a single pivoting shaft or other configurations for rocker arm  64  may be utilized. Solenoids  60 ,  62  are connected to each other and to rocker plate  64  with a link  65  and are actuated independently from each other, i.e., only one of the solenoids is actuated at a time to drive the rocker plate. A pair of arms  70 ,  72  are connected to rocker plate  64  adjacent opposite ends of the plate so that rotation of rocker plate  64  drives the arms in opposite directions. As best shown in  FIG. 4 , arm  72  may be connected to rocker plate  64  with a shaft  74  to offset the arm from the plate to avoid interference with arm  70 . 
         [0033]    A first link  80  connects arm  70  to a first gate shaft  82  which is connected to the end  31  of gate  24 . Similarly, a second link  84  connects arm  72  to a second gate shaft  86  that is connected to the end  31  of gate  26 . Shaft  82  includes an axial extending opening  90  at a proximate end that receives a small diameter end  88  of shaft  86  such that the proximate ends (nearest arms  70 ,  72 ) of shafts  82 ,  86  are coaxial, but free to rotate independently of each other. Accordingly, arms  70 ,  72 , links  80 ,  84  and shafts  82 ,  86  transmit torque to gates  24 ,  26 , respectively, but not between one another. 
         [0034]    While as illustrated, end  88  of gate shaft  86  is received in opening  90  of shaft  82 , the proximate ends of first and second gate shafts  82 ,  86  may be mounted in a bearing block or bushing positioned between links  80 ,  84  such that the shafts share a common longitudinal axis but do not transmit torque to one another. Bushings or bearings may also be provided at or adjacent the distal ends of shafts  82 ,  86  to support the shafts. 
         [0035]    The use of the above-described linkage to slave the operation of gates  24 ,  26  together permits the use of a single actuator mechanism to simultaneously operate the gates. Accordingly, actuation of either of solenoids  60 ,  62  rotates rocker plate  64  to drive arms  70 ,  72  which operate through links  80 ,  84  and shafts  82 ,  86  to simultaneously counter-rotate gates  24 ,  26 . The use of the slaved linkage to counter-rotate gates  24 ,  26  also permits the drive and linkage to be mounted in an enclosure  92  having a relatively small cross-section since both gates rotate to the same side of conduit  16 . 
         [0036]    In an alternate variation, gates  24 ,  26  may be mounted on a single shaft such that the gates rotate in the same direction when actuated, i.e., the gates rotate to both sides of conduit  16 . However, a larger enclosure may be required for co-rotating gates since the arc defined by the combined travel of the gates will be larger. Similarly, an alternate drive unit such as a double acting solenoid, electric motor, pneumatic cylinder or other drive may be used in place of single acting solenoids  60 ,  62 . In still other embodiments, the gates may not be mechanically linked to one another. Rather, the operation of gates  24 ,  26  may be electronically linked and controlled to enable sequential as well as simultaneous operation of the gates as previously described, e.g.,  FIG. 6 . 
         [0037]    Referring to  FIGS. 4 and 5 , in one embodiment, pressure source  36  comprises a blower assembly  100  including a blower motor  102  and blower  104 . Blower  104  is connected to a vacuum chamber  106  on the inlet side of the blower and a pressure chamber  108  on the outlet side of the blower. Air enters or is discharged from the assembly through an inlet/out pipe  110  that may optionally be provided with a muffler or other sound suppression device. 
         [0038]      FIG. 5  illustrates the path of air through blower assembly  100  in the pressure mode (solid arrows) and in the vacuum mode (dashed arrows). In the pressure mode, the two-way valve  38  (shown in solid line) connects the vacuum chamber  106  of the blower assembly  100  to the inlet/outlet pipe  110  and connects the pressure chamber  108  to the port  32 . This routes outside air (atmosphere) drawn into the inlet/outlet pipe  110  sequentially through the manifold  112  into the vacuum chamber  106 , then through the blower  104  into the pressure chamber  108 , then through the tube  34  and port  32  into the conduit  16 . 
         [0039]    In the vacuum mode, the two-way valve  38  (shown in dotted line) connects the vacuum chamber  106  of the blower assembly  100  to the port  32  and connects the pressure chamber  108  to the inlet/outlet pipe  110 . This routes air drawn from the conduit  16  of the system through port  32  and tube  34  sequentially into the manifold  112 , into the vacuum chamber  106 , through the blower  104  into the pressure chamber  108 , then through the inlet/outlet pipe  110  to the atmosphere. Note that in the embodiment shown in  FIG. 5 , the direction of air flow through blower  104  and the manifold  112  does not change when switching between pressure and vacuum modes. This allows the illustrated system to use a single blower  104  running in the same direction for both pressure and vacuum modes; thereby avoiding the need for multiple blowers (more cost) or the need to reverse the direction of the blower (more time to switch and more maintenance). 
         [0040]    A pair of one-way (i.e., single acting) solenoids  114 ,  116 , controlled by controller  44 , drive two-way valve  38  between the pressure and vacuum positions. Solenoids  114 ,  116  are connected to valve  38  with a link  118  and are independently actuated to drive the valve to the pressure or vacuum positions. Alternatively, a double-acting solenoid, electric motor, pneumatic cylinder or other drive unit may be used in place of single-acting solenoids  114 ,  116 . In other embodiments, a blower assembly that reverses motor and blower direction to switch between pressure and vacuum modes may be used. In still other embodiments, separate pressure and vacuum sources may employed. 
         [0041]    The pneumatic system disclosed herein provides an apparatus for conveying a carrier through a conduit open to atmosphere at the sending and receiving stations. The system oblviates the need for sealed gates or doors at the stations, the associated controls, limit switches and drives for such gates. The system also provides for decelerating a carrier approaching the receiving station without special controls, valves and piping. 
         [0042]    The drawings and detailed description herein are to be regarded in an illustrative rather than a restrictive manner, and are not intended to limit the following claims to the particular forms and examples disclosed. On the contrary, further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments will be apparent to those of ordinary skill in the art. Thus, it is intended that the following claims be interpreted to embrace all such further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments.