Patent Publication Number: US-6336572-B1

Title: Liquid filling apparatus and method of using same

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a liquid filling apparatus for filling a liquid into containers in a specified amount in each container. 
     Apparatus of the type mentioned are already known which comprises an apparatus body having a liquid channel connected at one end thereof to a liquid tank and at the other end thereof to a filling nozzle, a metering cylinder provided in the channel between opposite ends thereof in communication with the ends for causing the liquid to be filled to flow into and out of the liquid channel by strokes of a piston housed in the cylinder, and a check valve disposed upstream from the metering cylinder of the liquid channel. The check valve is forced open by a negative pressure produced within the metering cylinder by the inflow stroke of the piston. 
     The liquids to be filled include those which contain a gas as it is or as dissolved in the liquid and are liable to release bubbles. Such liquids are, for example, a liquid which needs to be filled hot, a liquid which has not been treated for deaeration before feeding to the filling apparatus, and a liquid which is liable to alter in properties due to a pressure change. When subjected to a negative pressure produced within the metering cylinder, such a liquid releases bubbles. If the bubbles produced remain and collect within the metering cylinder, the amount of liquid to be filled decreases with time. 
     The decrease in the amount of liquid to be filled can be prevented by discharging the bubbles from the metering cylinder every stroke of the piston. For this purpose, it is conventional practice to produce turbulence within the metering cylinder by ingeniously shaping the cylinder, cause the bubbles produced in the cylinder to flow out of the cylinder along with the liquid to be filled and fill the outflow into a container. However, if the bubbles are placed into the container along with the liquid, the liquid is liable to bubble up or scatter to result in a lower filling capacity. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to prevent formation of bubbles within the metering cylinder and to provide a liquid filling apparatus which is free of the problems due to the occurrence of bubbles and a method of using the apparatus. 
     The present invention provides a liquid filling apparatus comprising an apparatus body having a liquid channel connected at one end thereof to a liquid tank and at the other end thereof to a filling nozzle, a metering cylinder provided in the liquid channel between opposite ends thereof in communication with the ends for causing the liquid to be filled to flow into and out of the liquid channel by strokes of a piston housed in the cylinder, and a check valve disposed upstream from the metering cylinder of the liquid channel, the liquid filling apparatus being characterized in that the apparatus comprises valve opening-closing means for mechanically operating the check valve so as to open the valve during the inflow stroke of the piston and to close the valve during the outflow stroke of the piston. 
     The liquid filling apparatus of the invention has valve opening-closing means for mechanically operating the check valve so as to open the valve during the inflow stroke of the piston and to close the valve during the outflow stroke of the piston. Accordingly, no negative pressure is produced within the metering cylinder by the inflow stroke of the piston, with the result that the liquid to be filled is prevented from releasing bubbles. The absence of bubbles entails the following advantages. First, the amount of liquid to be filled is stabilized. Second, the liquid can be filled in a satisfactory state, permitting a high-speed filling operation. Third, even if the liquid is deaerated insufficiently when to be fed to the filling apparatus, the liquid can be filled satisfactorily to improve the freedom of the plant equipment. Fourth, with no limitations imposed on the capacity or shape of the metering cylinder, the filling apparatus can be designed with greater freedom. 
     Preferably, the liquid filling apparatus comprises means for setting the check valve at large and small two degrees of opening. 
     According to an embodiment of the invention, the liquid filling apparatus further comprises a valve seat facing downstream with respect to the direction of flow of the liquid and provided on a peripheral wall defining the liquid channel at a portion thereof upstream from the metering cylinder; the check valve comprising a valve disk movable toward and away from the valve seat on the downstream side thereof with respect to the flow direction, and a spring for biasing the valve disk toward the valve seat; the valve opening-closing means comprising a fluid pressure cylinder having a piston rod and so disposed as to move the valve disk away from the valve seat by an advancing stroke of the piston rod; the setting means comprising a movable engaging member engageable with and disengageable from the piston rod, and an actuator for moving the engaging member so that the disengagement of the member from the piston rod and the engagement of the member with the piston rod correspond respectively to the large and small degrees of opening of the check valve. The check valve can then be set easily at the large degree of opening or alternatively at the small degree. 
     The engaging member may be so disposed as to be movable straight across the path of movement of the piston rod, the actuator being a fluid pressure cylinder having a piston rod connected to the engaging member. 
     The liquid filling apparatus may further be so adapted that the interior of the liquid channel is cleaned or deaerated with the check valve set at the large degree of opening, and that the check valve is set at the small degree of opening for the filling operation. The liquid channel can then be cleaned or deaerated rapidly, smoothly and efficiently, while the outflow and inflow strokes of the piston can be readily timed with the opening and closing of the check valve. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view in vertical section of a filling apparatus of the invention; 
     FIG. 2 is an enlarged fragmentary view in section of FIG. 1; 
     FIG. 3 is a plan view of the portion shown in FIG. 2; and 
     FIG. 4 is a stroke diagram showing piston strokes of a metering cylinder and a check valve operation as timed with the strokes. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An embodiment of the present invention will be described below with reference to the drawings. 
     FIG. 1 shows a filling apparatus which comprises a filling nozzle  12  disposed above the path of transport of a container conveyor  11 , a metering cylinder  13  for feeding the liquid to be filled to the nozzle  12  in a specified amount at a time, and a tank  14  for containing the liquid to be fed to the metering cylinder  13 . 
     The filling nozzle  12  comprises a vertical tubular nozzle body  21 , a net  22  provided at the lower end of the nozzle body  21  for causing the surface tension of the liquid within the nozzle body  21  to prevent the liquid from flowing down under gravity, a lower check valve  23  disposed within the nozzle body  21  at the approximate midportion of its height for permitting the passage of the liquid free therethrough downward, and a first fluid pressure cylinder  24  attached as directed downward to the upper end of the nozzle body  21  for opening the lower check valve  23  by pushing down. 
     The nozzle body  21  has a downward outlet  31  at its lower end and a lateral inlet  32  positioned above the check valve  23  and close to the upper end of the body. 
     The lower check valve  23  comprises a seat ring  33  provided on the inner surface of the nozzle body  21  at the midportion of its height, a poppet valve  34  positioned under and in intimate contact with the seat ring  33 , and a spring  35  for biasing the poppet valve  34  upward. 
     The fluid pressure cylinder  24  has a rod  36  extending into the nozzle body  21  and in bearing contact with the upper end of the stem of the poppet valve  34 . 
     The metering cylinder  13  comprises a horizontal cylinder body  41  having a closed end and a piston  42  housed in the cylinder body  41 . 
     The cylinder body  41  has close to its closed end an inlet  51  facing upward and an outlet  52  facing downward. The edge portion of the inlet  51  is provided with a connecting tubular portion  53  having a closed upper end and communicating with the inlet. 
     As shown in detail in FIG. 2, an upper check valve  61  is provided in the inside lower part of the connecting tubular portion  53  for permitting the liquid to pass through the inlet  51  downward. The tubular portion  53  has a lateral communication opening  62  at the approximate midportion thereof. The interior of the tubular portion  53  is divided into an upper part and a lower part by an elastic membrane  63  extending transversely of the tubular portion  53  and positioned immediately above the opening  62 . Connected to the central portion of upper side of the membrane  63  is the lower end of a vertical lift rod  64 . A horizontal support plate  65  is fixed to the top of the connecting tubular portion  53  in a cantilever fashion. The support plate  65  is provided on its upper surface with a pair of vertical rodlike spacers  66  positioned closer to its fixed end. A second fluid pressure cylinder  68  directed vertically downward is attached to the upper ends of the spacers  66  by a horizontal mount plate  67 . Attached to the free end of the support plate  65  is a third fluid pressure cylinder  69  directed horizontally laterally. 
     The upper check valve  61 , which has the same construction as the lower check valve  23 , comprises a seat ring  71  attached to the edge portion of the inlet  51 , a poppet valve  72  positioned under and in intimate contact with the seat ring  71 , and a spring  73  for biasing the valve  72  upward. The poppet valve  72  has an upper end face opposed to the central portion of lower side of the membrane  63  and spaced apart therefrom by a small clearance. 
     The lift rod  64  has a slide portion  74  in the form of a round bar and extending through the top of the connecting tubular portion  53  to project upward therefrom. The slide portion  74  is provided with a flange  75  at its upper end. 
     The second fluid pressure cylinder  68  has a piston rod  76  connected to the upper end of the slide portion  74 . The second cylinder  68  has a piston stroke equal to that of the first cylinder  24 . 
     The third fluid pressure cylinder  69  has a piston rod  77  projecting toward the lift rod  64 . An engaging member  78  is connected to the outer end of the piston rod  77 . The engaging member  78  slidably rests on the upper surface of the support plate  65  and has an engaging recessed portion  79 , which is open toward a direction opposite to the rod-connected end of the member  78 . The width of the opening is slightly larger than the outside diameter of the slide portion  74  but smaller than the outside diameter of the flange  75 . 
     FIG. 2 shows the piston rod  76  of the second cylinder  68  as retracted, and the piston rod  77  of the third cylinder  69  as advanced, with the recessed portion  79  of the engaging member  78  fitting to the slide portion  74 . In this state, a small clearance Cl is created between the flange  75  and the engaging member  78 . When the piston rod  76  of the second cylinder  68  is advanced, the flange  75  comes into contact with the engaging member  78 , whereby the piston rod  76  is halted. Accordingly, the stroke of the piston rod  76  of the second cylinder  68  is equal to the small clearance Cl. This stroke will be referred to as the “small stroke distance.” The small stroke distance is, for example, about 1 to about 2 mm. 
     When the piston rod  77  of the third cylinder  69  is retracted from the position shown in FIG. 2, the recessed portion  79  of the engaging member  78  is moved out of fitting engagement with the slide portion  74 , creating a large clearance C 2  between the support plate  65  and the flange  75 . This clearance is a large stroke distance of the piston rod  76  of the second cylinder  68 . The large stroke distance is, for example, about 8 mm. 
     The inlet  32  of the filling nozzle  12  is held in communication with the outlet  52  of the metering cylinder  13  by a lower connecting pipe  81 . The liquid tank  14  is held in communication with the opening  62  of the connecting tubular portion  53  by an upper connecting pipe  82 . This arrangement provides a continuous liquid channel extending from the liquid tank  14  to the outlet  31  of the filling nozzle  12  through the metering cylinder  13 . 
     The filling apparatus is further provided with a cleaning device (not shown in its entirety) for cleaning the interior of the apparatus when a filling operation is to be started or for a change of the liquid to be filled. The device has an adaptor  83  removably attachable to the outlet  31  of the filling nozzle  12 . 
     For the filling operation, the piston rod  76  of the second cylinder  68  is moved the small stroke distance, whereby the poppet valve  72  is moved upward and downward a stroke distance approximately equal to the small stroke distance to open and close the upper check valve  61 . 
     When the piston  42  is moved leftward in FIG. 1 with the upper check valve  61  left open, the liquid to be filled flows out of the tank  14  into the metering cylinder  13  through the inlet  51 . The upper check valve  61  is then closed, and the piston  42  is moved rightward, whereby the liquid within the metering cylinder  13  is sent into the filling nozzle  12  through the outlet  52  while being prevented from flowing upward by the valve  61 . The liquid sent in forces the lower check valve  23  open to flow down the nozzle body  21  and is discharged from the outlet  31  through the net  22 . 
     FIG. 4 shows the timing of the piston strokes and the opening-closing timing of the upper check valve. The piston  42  and the second fluid pressure cylinder  68  are operated as thus timed with each other. 
     For cleaning, the piston rod  76  of the second cylinder  68  is moved the large stroke distance. In this case, the lower check valve  23  is also left open mechanically by the operation of the first fluid pressure cylinder  24 . 
     In place of the liquid to be filled, a cleaning liquid is supplied to the liquid tank  14 . The cleaning liquid supplied to the filling apparatus is collected through the adaptor  81  after passing through the apparatus. 
     It is likely that air will be held trapped in the filling liquid channel, for example, before the start of filling operation. It is desirable to remove such air from the channel. The air can be smoothly discharged by moving the piston rod  76  of the second cylinder  68  the large stroke distance also in this case. 
     The piston rod  76  of the second cylinder  68  (valve opening-closing means) and the upper check valve  61  described are provided separately, and the movement of the cylinder piston rod  76  (valve opening-closing means) is used only when opening the upper check valve  61 , thereby allowing the upper check valve  61  to open and close basically following the movement of the piston  42  of the metering cylinder  41 , whereby errors in the operation of the cylinder piston rod  76  (valve opening-closing means) can be prevented from leading directly to errors in the amount of liquid to be filled. 
     Furthermore, the provision of the piston rod  76  (valve opening-closing means) and the upper check valve  61  which are separate makes it possible to divide the interior of the connecting tubular portion  53  into the upper and lower parts by the membrane  63 , rendering the filling liquid channel more sanitary. Although the cylinder piston rod  76  (valve opening-closing means) and the upper check valve  61  can be provided alternatively as connected together, it is then necessary to more accurately control the operation timing of the cylinder piston rod  76  (valve opening-closing means) and the stroke distance thereof since even a slight error in the operation of the cylinder piston rod  76  (valve opening-closing means) directly results in an error in the amount of liquid to be filled. 
     A servomotor is usable as the valve opening-closing means in place of the fluid pressure cylinder  68 . The use of the motor improves the accuracy and speed of operation. 
     The present invention is applicable not only to the liquid filling apparatus described above but also to other liquid filling apparatus insofar as the apparatus comprise an apparatus body having a liquid channel connected at one end thereof to a liquid tank and at the other end thereof to a filling nozzle, a metering cylinder provided in the channel between opposite ends thereof in communication with the ends for causing the liquid to be filled to flow into and out of the liquid channel by strokes of a piston housed in the cylinder, and a check valve disposed upstream from the metering cylinder of the liquid channel.