JP7506302B2 - Liquid Delivery Device - Google Patents

Description

The present invention relates to a liquid delivery device equipped with a pump for delivering liquid.

For example, when filling beverages, a filling device is known that supplies the beverage stored in a slightly pressurized tank through a liquid delivery pipe equipped with a liquid delivery pump to a pressurized tank, and then supplies the beverage in the pressurized tank through a filling nozzle to a container (Patent Document 1).

Patent No. 4311789

For example, in the configuration of Patent Document 1, if the filling operation in the filling section is stopped for a certain period of time, it becomes necessary to also stop the supply of liquid to the pressurized tank. In order to immediately stop the supply of liquid to the pressurized tank, it is possible to provide a valve in the liquid supply pipe before the pressurized tank and close this valve. However, since it takes time to completely stop the liquid supply pump, a lag occurs between the timing of valve closure and the timing of pump stop, resulting in water hammer in the liquid supply pipe.

The objective of the present invention is to prevent the occurrence of water hammer when liquid delivery is stopped in a liquid delivery device equipped with a pump for delivering liquid.

A liquid delivery device according to a first aspect of the present invention includes a first tank for storing liquid, a first pressurizing means for maintaining a first pressure inside the first tank, a second tank disposed downstream of the first tank, a second pressurizing means for maintaining a second pressure inside the second tank that is equal to or higher than the first pressure, a filling means disposed downstream of the second tank for filling a container with liquid, a pump provided in a pipe connecting the first tank and the second tank and for delivering the liquid in the first tank to the second tank, a first valve provided in a pipe between the pump and the second tank that can be opened and closed, a bypass passage connecting pipes upstream and downstream of the pump, a second valve for controlling flow through the bypass passage, and a control means for controlling the drive of the pump and the operation of the first and second valves, wherein the control means closes the first valve and opens the second valve to allow flow through the bypass passage when the pump is stopped.

The second invention of the present invention is a liquid delivery device according to the first invention, further comprising a level detection means for detecting the liquid level in the second tank, and the control means controls the operation of the pump based on a signal from the level detection means.

The third invention of the present invention is a liquid delivery device according to the second invention, characterized in that when the filling means starts filling the container, the control means closes the first valve and drives the pump in a state in which the second valve allows flow through the bypass passage, and when the rotation speed of the pump reaches a predetermined rotation speed or higher, the control means opens the first valve and blocks flow through the bypass passage with the second valve to deliver liquid to the second tank.

According to the present invention, in a liquid delivery device equipped with a pump for delivering liquid, it is possible to prevent the occurrence of water hammer when liquid delivery is stopped.

1 is a block diagram showing a configuration of a liquid delivery device according to an embodiment of the present invention (during a filling operation and a liquid delivery operation). FIG. 1 is a cross-sectional view showing a structure of a rotary pump according to an embodiment of the present invention. 3 is a cross-sectional view illustrating a liquid delivery operation of the rotary pump of FIG. 2. 10 is a block diagram of the liquid delivery device showing the states of the first and second valves when the liquid delivery operation is stopped. FIG. 11 is a graph showing problems that may occur when a lower limit value for the pump drive frequency is not set. 13 is a graph showing the timing for stopping the liquid delivery operation in the liquid delivery device of the present embodiment in which a lower limit value of the pump drive frequency is set. 11 is a block diagram of the liquid delivery device showing the states of the first and second valves when the pump drive frequency is equal to or lower than a lower limit during a filling restart operation. FIG. 11 is a block diagram of the liquid delivery device showing the states of the first and second valves when the pump drive frequency is equal to or higher than a lower limit during a filling restart operation. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a liquid delivery device according to one embodiment of the present invention.

The liquid delivery device 10 of this embodiment delivers the filling liquid F stored in the cushion tank (first tank) 12 to the filler tank (second tank) 14, and supplies it from the filler tank 14 to the filling machine (filling means) 16. The filling machine 16 is equipped with a number of filling nozzles 16A on the outer periphery of a rotating wheel, for example, and fills the filling liquid F supplied from the cushion tank 12 into containers such as bottles through each filling nozzle 16A. In this embodiment, the filling liquid F is a carbonated beverage containing relatively large solids such as nata de coco, muscat, and pineapple.

In this embodiment, which handles carbonated beverages, the gas phase in the cushion tank 12 is pressurized to pressure P1 by a pressurizing device (first pressurizing means) not shown and maintained at the same pressure, while the gas phase in the filler tank 14 is pressurized to pressure P2, which is higher than pressure P1, by a pressurizing device (second pressurizing means) not shown. However, for example, when handling a filling liquid that does not contain carbon dioxide, both tanks 12, 14 may be maintained at the same pressure.

The upstream end of the liquid supply pipe 18 is connected to the bottom of the cushion tank 12, and the downstream end of the liquid supply pipe 18 is connected to a predetermined height of the side wall of the filler tank 14. A supply pipe 20 that supplies the filling liquid F in the tank to the filling machine 16 is also connected to the bottom of the filler tank 14. The supply pipe 20 branches into many pipes in the filling machine 16, and supplies the filling liquid F to each filling nozzle 16A. Each filling nozzle 16A has a valve function, and the filling liquid F is filled into the container while the nozzle is inserted into the container.

A pump 22 for delivering the filling liquid F is provided midway through the liquid delivery pipe 18. In this embodiment, the pump 22 is, for example, a rotary pump. In addition, a first valve 24 for controlling the flow of the liquid delivery pipe 18 is provided downstream of the pump 22 on the liquid delivery pipe 18 and before the filler tank 14.

The liquid supply pipe 18 is provided with a bypass passage 26 that bypasses the pump 22. That is, one end of the bypass passage 26 is connected to the liquid supply pipe 18 near the suction port of the pump 22 between the cushion tank 12 and the pump 22, and the other end is connected to the liquid supply pipe 18 near the discharge port of the pump 22 between the pump 22 and the first valve 24, thereby connecting the upstream and downstream piping of the pump 22. The bypass passage 26 is provided with a second valve 28 that controls the flow of the bypass passage 26, and in this embodiment, an opening and closing valve is used as the second valve 28.

The filler tank 14 is also provided with a level sensor 30 that detects the liquid level H in the tank, and the signal from the level sensor 30 is sent to the control unit 32. Based on the signal from the level sensor 30, the control unit 32 can control the operation of the first and second valves 24, 28 and the drive of the pump 22 (rotor rotation speed).

During the filling operation, the pump 22 is driven with the first valve 24 open and the second valve 28 closed. This causes the filling liquid F in the cushion tank 12 to be supplied to the filler tank 14 through the liquid supply pipe 18. The filling liquid F stored in the filler tank 14 is sent to the filling machine 16 through the supply pipe 20 and filled into each container through each filling nozzle 16A.

During the filling operation, the pump 22 has its rotor rotation speed (frequency) feedback-controlled so that the liquid level in the filler tank 14 is maintained at a predetermined height H0, and the amount of filling liquid F supplied to the filler tank 14 through the liquid supply pipe 18 is controlled so as to balance with the amount of filling per unit time into the container by the filling machine 16. In the figure, closed valves are drawn in black, and open valves are drawn in white.

Figure 2 is a cross-sectional view showing the structure of a rotary pump 22, and Figures 3(a) to 3(c) are cross-sectional views showing the time-series movement of the filling liquid F pumped by the pump 22 of Figure 2. In Figure 2, the outer shell 22A of the pump 22 and the protruding portion 22C of the rotor 22B are shaded, and the white portion indicates the flow path. In Figure 3, the filling liquid F being pumped is shown by the shaded area, and the cross section of the pump 22 is shown as a white portion.

As shown in FIG. 2, the rotary pump 22 of this embodiment has a pair of rotors 22B inside an outer shell 22A. Each rotor 22B has a pair of fan-shaped protrusions 22C that extend radially outward in opposite directions, and each protrusion 22C has a fan shape that is slightly narrower than 1/4 of the circumference of the rotor 22B.

The rotation axes of the pair of rotors 22B are arranged in parallel inside the outer shell 22A, and both rotors 22B rotate in opposite directions at the same speed. Both rotors 22B are arranged so that the protruding portion 22C of one rotor 22B located between the rotors 22B is located between a pair of protruding portions 22C of the other rotor 22B, and the outer circumferential surface of the protruding portion 22C of one rotor 22B is approximately in contact with the outer circumferential surface of the main body (cylindrical portion) of the other rotor 22B.

The outer shell 22A has an elliptical cross section that surrounds the outer circumference of both rotors 22B. The suction port and discharge port of the pump 22 are provided at the center of both straight parts of the elliptical outer shell 22A, respectively, and open toward the middle part of both rotors 22B. In addition, the inner surface of the semicircular part of the elliptical outer shell 22A is configured so that the outer circumferences of the protruding parts 22C of both rotating rotors 22B move while maintaining a small gap from the inner surface of the semicircular part.

With the above configuration, the suction port and discharge port of the pump 22 are always separated by the rotor 22B, and as shown in Figures 3(a) to (c), the filling liquid F is pumped out in a predetermined amount from the suction port side to the discharge port side through the space defined by the front and rear protrusions 22C of the rotating rotor 22B and the inner surface of the semicircular portion of the outer shell 22A.

When the filling nozzle 16A of the filling machine 16 is closed to stop the filling operation into the container, the liquid delivery operation to the filler tank 14 must be stopped, so the first valve 24 must be closed and the pump 22 must be stopped. When the liquid level H of the filling liquid F in the filler tank 14 exceeds (reaches) a predetermined value H1 based on the signal from the level sensor 30, the control unit 32 determines that the filling operation in the filling machine 16 has stopped, closes the first valve 24, and stops the pump 22.

However, although the first valve 24 is immediately closed by a control signal from the control unit 32, there is a time lag before the liquid delivery by the pump 22 stops due to the rotational inertia of the rotor 22B. Therefore, if the first valve 24 is closed and the operation of the pump 22 is stopped at approximately the same time, the water hammer phenomenon occurs in the liquid delivery pipe 18.

To address this problem, the liquid delivery device of this embodiment closes the first valve 24, stops the operation of the pump 22, and simultaneously opens the second valve 28 to allow flow through the bypass passage 26. As a result, after the control unit 32 stops the operation of the pump 22, the filling liquid F that was sent to the discharge port side due to the inertia of the rotor 22B is returned to the suction port side, preventing the occurrence of the water hammer phenomenon. Figure 4 shows a state in which the first valve 24 is closed and the second valve 28 is opened to allow flow through the bypass passage 26.

Meanwhile, in this embodiment, the timing to stop the liquid delivery operation is determined based on whether the liquid level height H of the filling liquid F in the filler tank 14 has reached a predetermined value H1, but the liquid level height H fluctuates to a certain extent even while the filling operation is being performed. Therefore, the predetermined liquid level height value H1 for detecting the timing to stop the liquid delivery operation is set to a value greater than the liquid level fluctuation during the filling operation. However, if the timing to stop the liquid delivery operation is detected based on the liquid level height H1, the following problems arise.

Figure 5 is a graph to explain the above problem, with the horizontal axis representing time and the vertical axis representing the liquid level in the filler tank 14 (left vertical axis) and the drive frequency of the pump 22 (right vertical axis). In Figure 5, curve H represents the liquid level, and curve f represents the pump drive frequency.

During the filling operation, the driving frequency (rotation speed) f of the pump 22 is controlled based on the signal from the level sensor 30 so that the liquid level H in the filler tank 14 is maintained at a predetermined value H0. At this time, if the liquid levels in the cushion tank 12 and the filler tank 14 are at the same level, the pump 22 is driven at a frequency (rotation speed) f0 such that the discharge pressure ΔP is ΔP > (P2 - P1), and the filling liquid F is supplied from the cushion tank 12 to the filler tank 14 through the liquid supply pipe 18 at a predetermined flow rate Q corresponding to the filling amount in the filling machine 16.

If the filling operation in the filling machine 16 is stopped at time t0 for some reason, the filling liquid F is no longer supplied from the filler tank 14 to the filling machine 16, and the liquid level H in the filler tank 14 rises. The control unit 32 reduces the driving frequency (rotation speed) f of the pump 22 from f0 to maintain the rising liquid level H at H0, but the filling liquid F in the filler tank 14 is not discharged, so the liquid level H continues to rise slowly. If the driving frequency f of the pump 22 falls below a certain frequency, the discharge pressure ΔP of the pump 22 falls below the pressure difference (P2-P1) between the two tanks (ΔP<(P2-P1)), and the filling liquid F flows back through the liquid supply pipe 18 and the pump 22.

As a result, the liquid level H in the filler tank 14 starts to drop before it reaches the liquid level H1 at which the liquid transfer operation stops, and the control unit 32 again increases the drive frequency (rotation speed) f of the pump 22 as the liquid level H drops. This increase and decrease in the drive frequency f of the pump 22 is repeated in small increments around ΔP = (P2 - P1), and the discharge pressure ΔP of the pump 22 finally stabilizes at the drive frequency fs (< f0) at which ΔP = (P2 - P1). Therefore, the liquid level H converges to a constant height Hs (H0 < Hs < H1) and reaches an equilibrium state without reaching the predetermined height H1 for stopping the liquid transfer operation. In the equilibrium state, the pump 22 is driven at the frequency fs, so the filling liquid F in the liquid transfer pipe 18 is stirred by the pump 22.

When the filling liquid F is a liquid containing gas such as carbon dioxide, backflow of the filling liquid F in the liquid supply pipe 18 and pump 22, and operation of the pump 22 in the above-mentioned equilibrium state, causes bubbles to form in the cushion tank 12, filler tank 14, and liquid supply pipe 18, and also places a load on solids in the liquid, causing them to be crushed or damaged. Therefore, if the control shown in Figure 5 is performed, the container will be filled with foamy filling liquid F when the filling machine operation is resumed, and normal filling will not be possible.

For the above reasons, in this embodiment, as shown in the graph in Figure 6, a lower limit value f1 is set for the drive frequency f of the pump 22. Note that Figure 6 corresponds to Figure 5, and the procedure for stopping the liquid delivery operation in this embodiment will be described with reference to Figure 6.

As shown in FIG. 6, until the time t0 when the filling operation in the filling device 16 is stopped, the driving frequency f of the pump 22 and the liquid level H of the filler tank 14 change in the same manner as in FIG. 5. In this embodiment, the lower limit value f1 of the driving frequency f is set to a frequency that is slightly higher than the driving frequency fs in the equilibrium state and does not cause backflow (fs<f1<f0). Therefore, when the filling operation is stopped (time t0), the liquid level H rises, and the driving frequency f of the pump 22 reaches the lower limit value f1, the driving frequency f is fixed to the lower limit value f1. Since the lower limit value f1 is higher than the driving frequency fs in the equilibrium state, ΔP>(P1-P2), and the liquid level H in the filler tank 14 continues to rise and reaches the predetermined value H1 at which the liquid transfer operation is stopped. When the liquid level H=H1 due to a signal from the level sensor 30, the control unit 32 stops the liquid transfer operation (time t1). That is, as described above, the pump 22 is stopped, the first valve 24 is closed, and the second valve 28 is opened at the same time.

Figures 7 and 8 are block diagrams showing the procedure for resuming filling. Below, the procedure for resuming filling in this embodiment will be explained with reference to Figures 7 and 8.

When the filling and liquid delivery operations are stopped, the pump 22 is stopped, the first valve 24 is closed, and the second valve 28 is open (Figure 7). When the filling operation is resumed, the pump 22 is first started in the state shown in Figure 7. Immediately after starting, the driving frequency f of the pump 22 is lower than the lower limit value f1, but the driving frequency f is gradually increased. When the driving frequency f of the pump 22 reaches the lower limit value f1, the first valve 24 is opened and the second valve 28 is closed, resulting in the state shown in Figure 8. After that, the normal liquid delivery operation using feedback control based on the signal from the level sensor 30 described above is started, and the filling operation in the filling machine 16 is started.

As described above, this embodiment can prevent the occurrence of the water hammer phenomenon when the liquid delivery operation is stopped. This can prevent, for example, damage to solids contained in the filling liquid and the generation of bubbles in carbonated liquid, etc.

In addition, in this embodiment, by setting a lower limit for pump control, the timing for stopping the pump can be calculated based on the liquid level even when the pump is feedback controlled using the liquid level in the tank as the controlled quantity.

In addition, because a rotary pump is used in this embodiment, even if the filling liquid contains solid matter, the pump can pump the liquid without damaging the solid matter.

In this embodiment, the pump is stopped when the liquid level in the filler tank reaches a predetermined value, but the timing of stopping the liquid delivery operation can be independent of the liquid level, for example, when the pump drive frequency reaches a lower limit value f1. In addition, in the case of carbonated beverages, the drive frequency fs at which ΔP = (P2 - P1) varies depending on the type of liquid, so by determining the drive frequency fs at equilibrium for each type of liquid and setting the lower limit value f1 of the drive frequency f, it becomes possible to handle multiple liquids.

In addition, in this embodiment, an opening/closing valve is provided in the bypass passage as the second valve, but a three-way valve may be used as the second valve at the branch point of the liquid supply pipe and the bypass passage, and the pump discharge port may be connected to the liquid supply pipe side during the liquid supply operation and connected to the bypass passage when the pump is stopped.

In this embodiment, a carbonated beverage is used as an example, so the second tank (filler tank) is maintained at a higher pressure than the first tank (cushion tank), but depending on the type of filling liquid, it is possible to maintain the same pressure in both tanks.

10 Liquid delivery device 12 Cushion tank (first tank)
14 Filler tank (second tank)
16 Filling machine (filling means)
18 Liquid delivery pipe 22 Pump 24 First valve 26 Bypass passage 28 Second valve 30 Level sensor 32 Control unit (control means)
F. Filling Fluid

Claims (3)

a first tank for storing a liquid;
a first pressurizing means for maintaining an inside of the first tank at a first pressure;
A second tank disposed downstream of the first tank;
a second pressurizing means for maintaining an interior of the second tank at a second pressure equal to or higher than the first pressure;
a filling means disposed downstream of the second tank for filling a container with liquid;
a pump provided in a pipe communicating between the first tank and the second tank, the pump sending the liquid in the first tank to the second tank;
a first valve that is provided in a pipe between the pump and the second tank and that can be opened and closed;
a bypass passage communicating between the upstream and downstream pipes of the pump;
a second valve for controlling flow through the bypass passage;
a control means for controlling the driving of the pump and the operation of the first and second valves;
The liquid delivery device, wherein the control means closes the first valve and opens the second valve to allow flow through the bypass passage when stopping the pump. The liquid delivery device according to claim 1, further comprising a level detection means for detecting the liquid level in the second tank, and the control means controls the operation of the pump based on a signal from the level detection means. The liquid delivery device according to claim 2, characterized in that when the filling means starts filling the container, the control means closes the first valve and drives the pump in a state where the second valve allows flow through the bypass passage, and when the rotation speed of the pump reaches a predetermined rotation speed or higher, the control means opens the first valve and blocks flow through the bypass passage with the second valve to deliver liquid to the second tank.

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