Abstract:
A device for mixing and metering one or multi-component compounds from at least one cartridge. These compounds can be in the form of a basic component and a catalyst component for impression compounds for dental applications. This device includes a punch for admitting pressure to the cartridge. This punch is supported in a displaceable manner, and is associated with each cartridge. This device also includes a hydraulic circuit which is associated with said at least one punch so that it actuates a piston or a cylinder of a hydraulically actuated piston cylinder unit. This device includes at least one pump and a supply container. This invention also includes a valve arrangement for this device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    Applicant claims priority under 35 U.S.C. §119 of German Application No. 103 12 843.3 filed Mar. 21, 2003. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a device for dispensing either one component or multi-component compounds from at least one cartridge. This device includes a punch that is supported in a displaceable manner which is associated with each cartridge and is used to apply pressure to the cartridge. These devices are used as metering and mixing devices for dispensing a basic component and a catalyst component. These components are mixed with each other to form a compound for producing impressions in the dental field.  
           [0003]    The cartridges are formed as hose like pouches that are emptied by the pressure applied by the punches, so that the components discharged into the mixer are blended in this mixer to obtain a compound that is ready to be used for impressions. In addition, this invention relates to a valve arrangement that can be used with this type of a device.  
           [0004]    Devices for dispensing compounds are known in the art. For example, European Patent No. EP 492 413 A1 discloses two plungers that can be displaced from cartridges for mixing and dispensing two-component compounds. These plungers are jointly driven by an electric motor via a magnetic clutch and a chain drive. At the same time, this motor is rotationally driving a shaft which is connected to the mixer to intimately blend the components with each other.  
           [0005]    In addition, a dispensing device for cartridges is also known from the art. For example, European Patent No. EP 1 101 538 A2 discloses a set of tappet plates that can be displaced with a carriage by means of an electromechanical driving system and threaded spindles. In addition, a device for dispensing a multi-component compound is also disclosed by European Patent No. EP 1 010 401 A1. With this device, the punch acts on cartridges that can be driven by an electric motor via a threaded spindle.  
           [0006]    Furthermore, European patent No. EP 787 515 B discloses a dispensing device for dispensing at least two components. This device comprises a metering cylinder with a feeding plunger for each component. This device also includes a drive unit that is actuated either electrically, pneumatically, or by hand for operating this device.  
           [0007]    After these devices have been shut off, the drive of the plungers should come to a standstill immediately to prevent the feed of the two components that are to be mixed with each other. Thus, this feeding will not continue, so that the dispensed compound can be exactly metered out and so that it is not contaminated by flowing back into a mixer and thus, these components will not set back in the mixer.  
           [0008]    To control this flow, and prevent the setting of these components in the mixer, European Patent No. 492 413 A1 uses a magnetic clutch that can be engaged and disengaged when the motor drive of the plunger is switched on and off. With this design, the plungers are connected with the motor drive via this magnetic clutch. Thus, this structure for applying single- or multi-component compounds is made very complicated and therefore, the manufacture of this type of a device is very expensive. Additionally, many components required for the drive of these plungers are subject to repair. The operating costs of these plungers is high as a consequence of the required maintenance and repair work.  
           [0009]    In addition, another drawback with some of the known devices listed above is that it is possible that after the drive has been shut off, one of the components may flow from a first cartridge into a mixer or into a second cartridge, where it will mix with the other compound received there. When the components comprise a basic component and a catalyst component, these components cure in the mixer so that this mixer gets clogged and becomes unstable.  
           [0010]    Therefore, the problem of the invention is to provide a device which can exactly meter out components with a high volume output of dispensed material, wherein this device requires a low amount of repair work, and wherein this device can be manufactured with a minimal number of components, in a compact way, and at a favorable cost.  
           [0011]    In addition, another problem of the invention is to provide a valve arrangement with a high volume opening that can be opened with low setting forces even at high pressure.  
         SUMMARY OF THE INVENTION  
         [0012]    To resolve the above problems associated with the references discussed, the invention relates to a device for metering out compounds that has a hydraulic system or circuit in communication with at least one punch for actuating a piston or a cylinder of a hydraulically actuated piston-cylinder unit. This hydraulically actuated piston cylinder unit comprises at least one pump and at least one supply container or reservoir.  
           [0013]    By using a hydraulically actuated piston-and-cylinder unit, wherein at least one piston is displaced in the device, it is possible to have particularly exact metering of the compounds that are dispensed. This is because the pressure that is hydraulically applied to the one or more plungers or pistons can be built up quickly and also reduced again rapidly after the device has been switched off. In addition, it is also possible to omit the toothed racks, chain drives, toothed gear drives, spindles or similar devices which are usually required with these type devices for translating a rotational movement of a drive shaft into a linear or axial movement of a piston. Thus, this means that the device can be built with a more compact structure and with fewer components which allows a reduction in the manufacturing costs.  
           [0014]    In addition, at the same time, this hydraulically actuated piston and cylinder unit operates almost free of maintenance and with a low susceptibility to repair.  
           [0015]    With a device having a plurality of cartridges and pistons, it is possible to have or to allocate a piston- and cylinder unit to each punch. Such a unit may be actuated by hand, so that the components can be dispensed from the cartridges with a dispensation volume that can be adjusted to an exact amount or level. In this way, the adjustable dispensation volume permits different mixing ratios that can be adjusted in a defined manner for each cartridge.  
           [0016]    In a preferred embodiment of the invention, at least one of the punches is a piston, or a cylinder of a hydraulically actuated piston-cylinder unit.  
           [0017]    This device can be manufactured in a particularly space saving way because at least one of the punches serves as a piston or cylinder of the piston cylinder unit and at the same time as a punch that is acting on the cartridges. In addition, the number of components required for building the device can be further reduced so that it is simpler in design.  
           [0018]    This punch can be formed as a cylindrical tube that is closed on the side facing the cartridges. This type of tube can be displaced as a cylinder moving in a fixed piston. This cylinder is consequently sliding in a fixed piston so that the required length of the device corresponds with only the length of the extended piston and cylinder unit. This type of an arrangement of the cylinder with a plunger, without a piston rod to which a pressure medium is admitted only on one side, is called a plunger-cylinder.  
           [0019]    If the plunger is designed to form a hollow plunger, this type if device can serve as a reservoir in the hydraulic circuit. Thus, it is not necessary to create a separate supply container for oil or some other type of suitable hydraulic fluid. This structure of the device as defined by the invention is thus simplified, so that the space required for this type of construction can also be reduced.  
           [0020]    In another preferred embodiment of the invention, the piston-cylinder unit comprises a hollow plunger so that on the side facing the punch, there is a valve comprising a valve disk. This valve disk can be positioned in a sealing manner against a first valve seat and against the force of at least one spring by means of the pressure in the fluid contained in the cylinder. When the pump is actuated, the pressure of the fluid in the cylinder builds up, automatically closing the valve in the first valve disk, which is pressed in a sealing manner against the valve seat against the force of the spring. A control system that would require an additional expense for a closing valve can be avoided with this arrangement.  
           [0021]    The first valve seat and the first valve disk can be penetrated by a bar on which a second smaller valve disk is formed on its end facing the cylinder. Via the pressure of the fluid in the cylinder, this second valve disk can be driven and placed in a sealing manner against a second valve seat that is in the first larger valve disk. This bar which supports the second valve disk, permits a quick relief of the pressure of the fluid in the cylinder after the pump has been switched off. The second, smaller valve disk is detached from the second valve seat via the bar, so that the fluid can drain through the first valve disk from the cylinder into the hollow plunger. When the pressure of the fluid in the cylinder has been relieved, the first larger valve disk is lifted from the valve seat by the springs applying a force. Thus, the fluid can now flow from the cylinder into the hollow plunger with a high flow volume.  
           [0022]    Alternatively, the pressure of the fluid can be relieved from the cylinder after the pump has been shut off by providing the pump with a defined leakage of 0.2 ml/s. When this pump has been shut off, a portion of the hydraulic fluid can then flow through the pump and back into the reservoir. This leakage lowers the pressure of the fluid in the cylinder so that the first valve disk will be lifted from the first valve seat by the force of the at least one spring. Thus, the fluid can also flow through the valve from the cylinder into the supply container with a high flow volume.  
           [0023]    The first valve seat can be formed as a cap that comprises at least one opening that can be closed by the first valve seat, and a second, smaller opening for feeding fluid from the pump into the cylinder. With this embodiment, the hollow plunger serves as both a supply container for the hydraulic fluid and also as a location for the extension of the pressure line from the pump to the cylinder. Thus, this structure can be further simplified to reduce the space required for construction.  
           [0024]    For an exact metering of the compounds, the device can have two punches that have the same or substantially the same length but different diameters. These two punches are supported in parallel with each other in a displaceable manner in a common plunger-cylinder unit. These two punches are preferably connected with a carriage or bracket that is supported in a displaceable manner on at least one rail. Thus, these two punches are guided on the rails via the carriage in parallel with each other, so that any canting or deviation of the punches is avoided. In addition, with this design, the cylinder does not need any special guidance on the hollow plunger because the cylinder is guided via the carriage. This type of guidance of the punches on the carriage reduces the friction of the punches and the friction of the plunger-cylinder unit as well.  
           [0025]    To exchange or replace the cartridges, the punches may need to be moved rapidly from an extended position of the plunger-cylinder unit into a retracted position. A hand wheel can be used to displace or move the carriage by hand. In addition, the punches can also be displaced by using a hand wheel coupled with a pinion that can engage a toothed rack. Consequently, the carriage with the punches can be moved by both turning the hand wheel along with the toothed rack and by driving it manually when the pinion is disengaged from the toothed rack. Thus, the pinion can then be supported either in a stationary manner on a frame or similar device, while the toothed rack is being displaced together with the punches in relation to the stationary toothed rack.  
           [0026]    The components that are dispensed from the device, are preferably blended in a mixer or spout that can be driven via a shaft of the mixer. This shaft can be connected with a motor, such as a device that drives a toothed belt that is driving the pump as well.  
           [0027]    In another embodiment of the invention, the shaft driving the mixer is supported in a manner substantially parallel with the axis of rotation of the mixer. On the side facing the mixer, this shaft supports a toothed gear that can engage a pinion that is disposed on the mixer in a detachable manner.  
           [0028]    The replacement of cartridges and the mixer can be assisted by retracting the shaft from a position in which the shaft engages the mixer, via a release mechanism, when the motor is not operating. The motor, the release mechanism, and the bar supporting the second valve disk can be jointly actuated via a switch. This switch makes it possible to simultaneously switch on the motor that is driving the pump and the shaft, actuate the release mechanism to engage the shaft of the mixer, and move the bar into a position. This causes the second valve disk to be retained in a sealing manner on the second valve seat in the first valve disk, so that a pressure of the fluid in the cylinder is built up. However, it is also possible by using the switch to shut the motor down, to disengage the shaft from the mixer, and to detach the second valve disk from the second valve seat, so that the pressure of the fluid in the cylinder is relieved and the first valve disk is lifted from the valve seat.  
           [0029]    If the plunger-cylinder unit has a double-action cylinder, it is also possible to displace the carriage with the punches by driving it hydraulically in both directions. It is also possible to drive the carriage at different speeds.  
           [0030]    In addition, this invention relates to a valve arrangement that is suited for controlling a plunger-cylinder unit in a device of the type specified above. This valve arrangement comprises a first, larger opening that comprises a first valve seat, and wherein this device can be closed in a sealing manner by a first, larger valve disk. In this case, the first valve disk can have a second smaller opening that comprises a second valve seat, and wherein this second valve seat can be closed in a sealing manner by a second smaller valve disk. This first valve seat can be moved into its position wherein it is lifted from the first valve seat via at least one pressure spring. Thus, it is possible to detach the second valve disk from its valve seat with relatively low force even if the pressure acting on the valve disk is high. A rapid pressure relief is thus achieved, so that the first valve disk can be easily lifted from its valve seat. Consequently, a high volume of flow can be passed through the first opening of this valve arrangement without having the opening of the valve arrangement impaired by the high forces acting on the first valve disk.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0031]    Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings which disclose at least one embodiment of the present invention. It should be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the invention.  
         [0032]    In the drawings, wherein similar reference characters denote similar elements throughout the several views:  
         [0033]    [0033]FIG. 1 is a schematic perspective view of the device according to the invention;  
         [0034]    [0034]FIG. 2 is a schematic perspective view of the components of the hydraulic circuit according to FIG. 1;  
         [0035]    [0035]FIG. 3 is a schematic perspective view of the valve arrangement as defined by the invention;  
         [0036]    [0036]FIG. 4 is a schematic perspective view of the valve according to FIG. 3 with an actuating device; and  
         [0037]    [0037]FIG. 5 is a partially exploded view of the valve arrangement shown in FIG. 3. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0038]    Referring now to the drawings, FIG. 1 shows a device  1  for dispensing two components, for example, a basic component and a catalyst component for dental impression compounds. Device  1  comprises a U-shaped frame  2  that is connected on two opposite ends with an abutment or end plate  3  and a plunger plate or piston plate  4 . In the area of device  1  facing abutment  3 , two cartridges cylindrical chambers or feeding tubes  5   a  and  5   b  are disposed in frame  2  and extend through abutment  3 , as shown in FIG. 1. Hose-like (or tubular) pouches that contain, for example, a basic component and a catalyst component for producing impression compounds for dental application, can be disposed in these cartridges. In the area of the abutment  3 , cartridges  5   a  and  5   b  have dispensing openings that, in the present embodiment, feed into a dynamic mixer or spout  6 . Dynamic mixer  6  allows the components to thoroughly mixed and discharged from device  1 .  
         [0039]    To dispense the components from cartridges  5   a  and  5   b , punches, cylinders or pushers  7   a  and  7   b , respectively, are associated with each cartridge for squeezing out the components. These punches  7   a  and  7   b  are insertable in cartridges  5   a  and  5   b . To actuate punches  7   a  and  7   b , device  1  can include a piston-cylinder unit  8  formed by a hollow plunger or piston  9 , which is connected with piston plate  4  in a fixed manner, and punch  7   a  that serves as the cylinder. The two punches  7   a  and  7   b  are connected to each other in a fixed way via carriage or bracket  10 , so that punches  7   a  and  7   b  can be jointly displaced in frame  2  in parallel with one another. For this purpose, frame  2  has rails  11  on which carriage  10  slides. Alternatively, each punch  7   a , and  7   b  can have a separate piston-cylinder unit  8  to actuate punches  7   a  and  7   b  independently of each other.  
         [0040]    A geared motor  12  driving pump  13  is arranged on the side of the U-shaped frame  2  shown as the bottom side in FIG. 1. The suction line of pump  13  is connected with the interior of piston  9  which is formed as a hollow piston. Thus, this piston serves at the same time as a reservoir for hydraulic fluid. The pressure line of pump  13  extends through hollow piston  9  and feeds into punch  7   a  on the side of hollow piston  9  that faces mixer  6 . Punch  7   a  serves as the cylinder of piston-cylinder unit  8 .  
         [0041]    The side of hollow piston  9  that faces mixer  6  is closed versus the cylinder (punch) by a cap  14  with a double valve. This cap is shown in FIG. 3. Cap  14  has a small opening  15 , into which a pressure line (not shown) of the pump  13  feeds into. Furthermore, cap  14  is has a larger opening  16  that can be closed in a sealable manner by pressing a first, larger valve disk  17  against a first valve seat in cap  14 . A plurality of pressure springs  29  are shown in FIG. 5 which shows an exploded drawing of FIG. 3. These pressure springs  20  are arranged between valve disk  17  and cap  14 . These pressure springs  29  retain valve disk  17  in a position that is removed from the valve seat in cap  14 , so that a fluid can pass through opening  16  in cap  14 .  
         [0042]    Cap  14  and the first, larger valve disk  17  are penetrated by a bar  18 . The bar can have a second, smaller valve disk  19  on the side of the bar shown in FIG. 3. Via bar  18 , second valve disk  19  can be displaced into an open position from the closed position shown in FIG. 3, wherein second valve disk  19  is pressed in a sealable manner against a valve seat formed in first valve disk  17 . In this open position, second valve disk  19  is lifted from the second valve seat in first valve disk  17 . It is then possible for a fluid to flow through first valve disk  17  from cylinder  7   a  and hollow plunger  9 . The two valve disks  17  and  19  thus form a double valve.  
         [0043]    [0043]FIG. 4. shows on the side facing away from second valve disk  19 , bar  18  which is connected with a rocker arm  20  that can pivot via a release device  21 . This release device can be actuated by a switching shaft  22 . A shaft  23  of the mixer can be oppositely displaced in relation to bar  18  in an axial direction. Mixer shaft  23  can be driven by motor  12  via a driving means not shown in the figures. This driving means can be, for example by a driving means such as a toothed belt, a chain or a similar drive means, and engages mixer  6  with its end  24  located on the side of the mixer when bar  18  presses second valve disk  19  against the second valve seat in the first valve disk  17  via rocker arm  20 . As an alternative to the embodiment shown, shaft  23  of the mixer can be supported substantially in parallel with the axis of rotation of mixer  6 . Mixer shaft  23  has a toothed gear that can be engaged with a pinion of mixer  6 . When mixer  6  is mounted in device  1 , this mixer is automatically connected with the shaft of the mixer via a toothed gear and pinion.  
         [0044]    Furthermore, in U-shaped frame  2 , there is a lateral slot-like window  25  that has a toothed rack  26  on its side shown in FIG. 1 as the upper side. A hand wheel  27  is associated with carriage  10  supporting punches  7   a  and  7   b . This hand wheel is connected with a pinion (not shown). This pinion can be engaged with toothed rack  26  in side window  25 , so that the carriage with punches  7   a  and  7   b  can be displaced along the toothed rack  26  by turning hand wheel  27 . When the pinion is disengaged from the toothed rack, carriage  10  can be freely displaced on rails  11  via hand wheel  27 .  
         [0045]    The function of device  1  is explained below in greater detail. To dispense a compound for producing dental impressions from cartridges  5   a  and  5   b  containing a basic component and a catalyst component, cartridges are jointly inserted in device  1  which serves as a mixing and metering device. Punches  7   a  and  7   b  are retracted so that carriage  10  is disposed close to piston plate  4 . Shaft  23  of the mixer is in a position in which it is retracted in the direction of piston plate  4 , so that cartridges  5   a  and  5   b  and mixer  6  can be jointly inserted in device  1 .  
         [0046]    Punches  7   a  and  7   b  associated with cartridges  5   a  and  5   b , respectively, are now jointly inserted in cartridges  5   a  and  5   b  via carriage  10 . This can be accomplished either by turning hand wheel  27 , whereby the pinion connected with hand wheel  27  engages toothed rack  26  of side window  25 , or by displacing carriage  10  if the pinion is disengaged from toothed rack  26 . Thus, it is possible also to drive punches  7   a  and  7   b  into the cartridges by actuating plunger-cylinder unit  8 . To achieve this result, the switching shaft  22  is actuated, so that mixer shaft  23  is driven into mixer  6  with its end  24  located on the side of the mixer, and wherein bar  18  is retracted at the same time in the direction of piston plate  4 , so that second valve disk  19  is pressed against the second valve seat in first valve disk  17  in a sealing manner. Motor  12 , which drives pump  13  and mixer shaft  23 , is simultaneously switched on by such actuation of switching shaft  22 .  
         [0047]    A hydraulic fluid, for example oil or a similar type fluid can flow from hollow plunger  9  serving as the reservoir, through pump  13  and via opening  15  in cap  14  into cylinder  7   a . The fluid flowing into cylinder  7   a  causes a pressure to build up in cylinder  7   a , so that first valve disk  17  is pressed in a sealable manner against the first valve seat in cap  14  against the force of springs arranged between said first valve disk and cap  14 . By having a rising pressure of the fluid in cylinder  7   a , it moves in relation to hollow plunger  9  in the direction pointing away from piston plate  4 , so that carriage  10  with two punches  7   a  and  7   b  are inserted in cartridges  5   a  and  5   b , respectively, for dispensing the components.  
         [0048]    To switch off device  1 , switching shaft  22  is pivoted in the opposite direction, so that mixer shaft  23  is engaged from mixer  6  and the motor is stopped. Bar  18  is moved at the same time in the direction of mixer  6 , so that second valve disk  19  is lifted from its valve seat in first valve disk  17 . The pressure of the fluid in cylinder  1   a  can be rapidly relived, so that also first valve disk  17  is lifted from its valve seat in cap  14  by the force, which can be generated by springs, which are disposed between valve disk  17  and cap  14 . Thus, the fluid can flow back from cylinder  7   a  into hollow plunger  9 . The pressure of the fluid in cylinder  7   a  is reduced so rapidly that any continuing flow of the components from cartridges  5   a  and  5   b  into mixer  6  is avoided. Consequently, no contamination of the components in the cartridges can occur.  
         [0049]    To replace cartridges  5   a  and  5   b , punches  7   a  and  7   b  can be retracted from the cartridges in the direction of piston plate  4  when motor  12  and driving pump  13  are switched off and second valve disk  19  is lifted from its valve seat in first valve disk  17 . Punches  7   a  and  7   b  can be displaced either by turning hand wheel  27 , if the pinion connected with hand wheel  27  engages toothed rack  26 , or by displacing carriage  10  on rails  11 , if the pinion is disengaged from toothed rack  26 . When second valve disk  19  is in this position, the hydraulic fluid can flow through the opening in first valve disk  17 . This opening is penetrated by bar  18 , and, if first valve disk  17  is lifted off its valve seat in cap  14 , it can flow back into hollow plunger  9  through cap  4  as well. Carriage  10  with punches  7   a  and  7   b  can therefore be displaced in both directions in a particularly smooth way.  
         [0050]    As an alternative to the manual retraction of carriage  10  with punches  7   a  and  7   b , it is possible to also hydraulically drive carriage  10  out of cartridges  5   a  and  5   b  if plunger-cylinder unit  8  has a double-action cylinder (not shown). In addition, it is possible via the control of the delivery of the pump to displace carriage  10  with punches  7   a  and  7   b  on rails  11  at different speeds, for example at a high forward and/or rearward speed, and at a slower speed of the operating lift.  
         [0051]    Accordingly, while at least one embodiment of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined in the appended claims.  
         [0052]    List of Reference Numerals and Letters  
         [0053]    [0053] 1  Device  
         [0054]    [0054] 2  U-shaped frame  
         [0055]    [0055] 3  Abutment/end plate  
         [0056]    [0056] 4  Piston plate/plunger plate  
         [0057]    [0057] 5   a ,  5   b  Cartridges/cylindrical chambers/feeding tubes  
         [0058]    [0058] 6  Mixer/spout  
         [0059]    [0059] 7   a  Punch/cylinder/pusher  
         [0060]    [0060] 7   b  Punch  
         [0061]    [0061] 8  Piston-cylinder unit  
         [0062]    [0062] 9  Hollow plunger/piston  
         [0063]    [0063] 10  Carriage/bracket  
         [0064]    [0064] 11  Rail/guide  
         [0065]    [0065] 12  Motor/drive  
         [0066]    [0066] 13  Pump  
         [0067]    [0067] 14  Cap/cover  
         [0068]    [0068] 15  Smaller opening  
         [0069]    [0069] 16  Larger opening  
         [0070]    [0070] 17  First valve disk/first valve cover  
         [0071]    [0071] 18  Bar/shaft  
         [0072]    [0072] 19  Second valve disk/second valve cover  
         [0073]    [0073] 20  Rocker arm  
         [0074]    [0074] 21  Disengaging device/release device  
         [0075]    [0075] 22  Switching shaft  
         [0076]    [0076] 23  Shaft of mixer  
         [0077]    [0077] 24  End on side of mixer  
         [0078]    [0078] 25  Side window/opening  
         [0079]    [0079] 26  Toothed rack  
         [0080]    [0080] 27  Hand wheel