JPH04256813A - Vacancy detecting apparatus for liquid container - Google Patents

Abstract

PURPOSE:To perform a required countermeasure by detecting the state wherein each container becomes vacant or close to vacant in a feeding method wherein automatic switching is performed to the other container when one of two flexible containers in which liquid is tightly sealed becomes vacant. CONSTITUTION:Two flexible containers 1 and 2 in which liquid is tightly sealed are connected to a liquid sucking and sending pump 6 through a selector valve 4. The pump 6 is operated by the first specified time. The selector valve 4 is switched from one to the other based on the fact that the value of the pressure in the pipe between the selector valve and the pump after the second specified time from the end of the pump operation is the preset value or less. It is judged that each of the containers 1 and 2 is vacant or close to vacant based on the fact that the switching operation is continuously performed twice within the third specified time.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is particularly useful in beverage vending machines, in which two flexible containers are prepared that contain beverage concentrate, and when one container becomes empty, the other container is automatically replaced. The present invention relates to an empty detection device for liquid containers, which detects when each container is empty or nearly empty when switching to a supply method, and takes necessary measures.

0002

2. Description of the Related Art Conventionally, there are two methods for discharging a stock solution. One is a method in which the stock solution contained in a metal container is pushed out by gas pressure from a carbon dioxide gas cylinder. The other method is to use a suction pump to suck up and discharge the stock solution sealed in a flexible sealed vinyl container, and in this case, the sealed vinyl container is disposable.

[0003] In the case of the first metal container, a reserve container capable of holding at least one sales volume is provided in the middle of the piping through which the stock solution is pushed out. When the stock solution in the metal container is consumed, the stock solution held in the reserve container will be used next. At this time, it is necessary to detect when the metal container is empty, but it is difficult to install a liquid level detector in the metal container, so In many cases, the interface with carbon dioxide gas is detected using, for example, an electrode type (capacitance type) liquid level sensor. Now, in the case of the metal container described above, the metal container must be cleaned when it is used again after containing the stock solution, which is time-consuming and poses a problem in terms of maintenance. Therefore, there has recently been a tendency to use disposable second flexible vinyl sealed containers.

[0004] Here, the detection that the stock solution in the flexible container has run out is performed based on the fact that the pipe pressure between the container and the suction/transport pump changes due to the stock solution running out. . That is, the pressure after suction by the pump for a certain period of time becomes a large negative pressure when the container is empty or nearly empty. Switching between containers is performed by turning on or off electromagnetic switching valves installed in the piping of each container by the control section based on the detection that the container is empty.

[0005]

The conventional techniques as described above have the following drawbacks. One is that the detection of empty container becomes uncertain when the viscosity of the stock solution is high. In addition to the remaining amount of stock solution, factors that change the pipe pressure include the viscosity and density of the stock solution, the inner diameter of the pipe,
There are factors such as length and suction power of the pump, and the viscosity of the stock solution has a particularly large influence. In other words, if the viscosity of the stock solution is high, the pipe pressure after pump suction for a certain period of time will show a large negative pressure even if there is a considerable amount of stock solution remaining, and there is a risk that it will be mistakenly recognized as if the remaining amount is small. be.

This is shown in the pressure time chart of FIG. 4, where the double solid line corresponds to when the stock solution has a high viscosity and there is a large amount remaining. The pressure after suction by the pump for time T1 is a large negative pressure state. Of course, if there is no remaining stock solution,
When the amount is low, as shown by the broken line, the pressure after suction by the pump at time T1 shows a large negative pressure, and judging from the pressure at this time, it is difficult to distinguish whether the remaining amount is low or the viscosity of the stock solution is high. . In addition, in the case of a stock solution with a low viscosity, there is no possibility of misidentification as described above. That is, when there is a large amount remaining, as shown by the solid line, the pressure drop during pump suction is small, and the pressure is quickly restored after suction is stopped. Although not shown here, when the remaining amount is low, a large negative pressure similar to that during pump suction is exhibited, so the remaining amount can be correctly detected by detecting the pressure at the time when pump suction is stopped.

Another drawback is that when each container is empty or nearly empty, a display means such as a display lamp is provided to indicate this, and when the empty container is replenished or replaced, the empty display is canceled. It is necessary to take measures such as turning off the lamp. When this procedure is done manually, it is not only time-consuming but also easy to forget in practice.
It becomes impossible to sell and causes inconvenience to users. Furthermore, if the release procedure were to be performed automatically, the device configuration would become more complicated and the cost would increase.

An object of the present invention is to solve the above-mentioned problems of the conventional technology by preparing two flexible containers that contain viscous liquid, and when one container is empty, the other container is An object of the present invention is to provide an empty liquid container detection device that detects when each container is empty or nearly empty when using a supply method that automatically switches containers, and takes necessary measures. .

[0009]

[Means for Solving the Problem] In order to solve this problem, a liquid container empty detection device according to claim 1 is provided with two flexible containers in which liquid is sealed and a liquid container that is connected to the liquid container via a switching valve. a pump that is alternatively connected and sucks and transports the liquid; a pressure sensor that measures the pressure in the piping between the pump and the switching valve; a predetermined time after the end of the predetermined operation of the pump; Based on the fact that the pressure value is less than or equal to a set value,
a switching control unit that switches the switching valve from the one container side to the other container side; based on the switching operation by the switching control unit being performed twice in a row within another predetermined time, each of the containers a determination unit that determines that it is empty or close to empty;
Equipped with A liquid container empty detection device according to a second aspect of the present invention is the apparatus according to the first aspect, wherein the predetermined operation of the pump is a suction operation for a first predetermined time. A liquid container empty detection device according to a third aspect of the present invention is the device according to the first or second aspect, in which the set value related to the pressure is determined in accordance with a predetermined remaining amount of each container. According to a fourth aspect of the present invention, there is provided a liquid container empty detection device according to any one of the first to third aspects, wherein the liquid is an undiluted beverage solution used in a vending machine.

0010

[Operation] In the liquid container empty detection device according to claim 1, the switching control section causes the pump to perform a predetermined operation, for example, as in claim 2, the pump is operated for a first predetermined time, and from the point at which the operation ends. Based on the fact that the pressure value after a predetermined time is less than or equal to the set value, the switching valve is switched from one container side to the other container side. Then, the determination unit determines that each container is empty or nearly empty based on the fact that the switching operation has been performed twice within another predetermined time period. According to claim 3, the set value related to the pressure can be determined corresponding to the predetermined remaining amount of each container, so even after it is determined that each container is empty or nearly empty, at least one Times are available.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid container empty detection device according to the present invention will be described below with reference to the drawings. FIG. 1 is a common configuration diagram of the first and second embodiments, and in the figure, 1
, 2 are flexible containers each containing a beverage concentrate, and are stored in a case 3. 4 is a switching valve, 5 is a pressure sensor, 6
is a pump for sucking and transporting the stock solution, and transports the stock solution to the supply destination on the right side of the figure. Reference numeral 7 denotes a switching control unit, which operates the pump 6, detects whether the connected containers 1 and 2 are empty based on the output of the pressure sensor 5, and switches the switching valve 4 based on the detection, as will be described in detail later. drive. Reference numeral 8 denotes a determination section, which determines, or detects, whether both containers 1 and 2 are empty or nearly empty, based on a signal from the switching control section 7, as will be described in detail later. By the way, the first example and the second example
The difference from the embodiment lies in the amount of stock solution remaining in the container when the empty state is detected; in the first embodiment, it is almost zero (more precisely, 1
In the second embodiment, at least one sales volume remains.

The operation of the switching control section 7 will be explained with reference to the time chart of pipe pressure shown in FIG. In Figure 4, the horizontal axis represents time T, and the vertical axis represents the pressure P detected by the pressure sensor 5 (see Figure 1). Shows changes over time. The double solid line indicates when a large amount of the high viscosity stock solution remains, and the broken line indicates when the high viscosity stock solution is empty or nearly empty. Note that the solid line indicates when a large amount of low-viscosity stock solution remains, as already described. At some point pump 6 (see Figure 1)
is activated, stopped after time T1, and then stopped after time T2.
Detect the pressure after. When the high-viscosity stock solution is empty or nearly empty, the detected pressure P2 remains lower than the set value Ps shown by the dashed-dotted line without recovering the state of pressure P1, which decreased during time T1, as shown by the broken line. become. On the other hand, when a large amount of high viscosity stock solution remains,
As shown by the double solid line, during time T1 the pressure P1 decreases to the same level as when the stock solution is empty or nearly empty, but after that it almost recovers and at least after time T2 the pressure P1 drops to the set value shown by the dashed-dotted line. The state exceeds Ps. Therefore, it is possible to detect whether the container is empty or not based on a comparison between the pressure after time T2 and the set value Ps. The amount of stock solution remaining in the container when empty is detected depends on how the set value Ps is determined.

The operation of the first embodiment will be explained with reference to the flowchart shown in FIG. In step S1, the empty detection operation as a subroutine, that is, the operation of the switching control section 7 explained in FIG. 4 is performed. As a result, step S
In step 2, the presence or absence of the sky detection signal V is determined, and if there is, the process proceeds to step S.
3, if there is none, the process moves to step S9. In step S9, since it is possible to sell, if there is a deposit, step S10
After the sale is made, it returns to the initial state. Step S
3, the switching valve 4 (see FIG. 1) is switched to switch the connection from one container to the other. Subsequently, in step S5, the timer T is started from zero (started after being reset), and an empty detection operation is performed in step S5. As a result, the presence or absence of the sky detection signal V is determined in step S6, and if there is, the process moves to step S7, and if not, the process moves to step S11. In step S11, the sale is possible, so when the money is received, the sale is carried out in step S12, and then the process returns to the previous stage of step S5. In step S7, the switching valve 4
is switched to switch the connection from one container to the other.

Next, in step S8, it is determined whether or not the timer T is less than the set value A. If it is less than the set value A, both containers are considered empty, and sales are stopped in step S13, and the series of processes ends. In step S8, if the timer T is equal to or greater than the set value A, the process returns to the previous stage of step S4. Here, the set value A corresponds to the third predetermined time period in the invention, and from the time when one container is switched to the other container based on the detection that it is empty, the other container is also detected to be empty and the switch is made again. This value is the time required to switch to one container side plus some extra time. Therefore, timer T
When is equal to or greater than the set value A, it means that sales from the other container have been made several times, and it is expected that one container side can be replenished or replaced during that time. Therefore, it is necessary to return to the previous stage of step S4 and check whether one container is empty. As a result of the check, if the empty detection signal V is output while the empty detection signal V is less than the set value A for one of the containers, it is confirmed that both containers are empty, and the process moves to step S13 to stop selling. It should be noted that since the empty detection signal V is not distinguished between one container and the other container, the determination process becomes easier.

The operation of the second embodiment will be explained with reference to the flowchart of FIG. The second embodiment is based on the first
In the embodiment, the empty state is detected when the remaining amount of stock solution becomes zero, but the empty state is detected when a predetermined amount of stock solution that can be sold N times remains. The flowchart in FIG. 3 is a partial flowchart that should be added after step S8 in FIG. 2, which is indicated by a broken line, in place of S13. Therefore, the operation of the second embodiment is expressed by modifying and adding the partial flowchart of FIG. 3 to the flowchart of FIG. 2. In FIG. 3, after step S8 in FIG. 2, that is, after a predetermined amount of undiluted solution remains in both containers, a counter i related to the number of additional sales is initialized in step S21, and a deposit is made in step S22. The sale in step S23 is carried out based on the existence of the item. Only after sales have been made a predetermined number of times based on the remaining amount in steps S24 and S25, sales are stopped in step S26. Therefore, even after each container is determined to be empty or nearly empty, it can be sold only N times, causing less inconvenience to users, and reducing the amount of time it takes for the equipment to replenish or replace containers. This will give you more leeway.

[0016]

In the liquid container empty detection device according to claim 1, the switching control section causes the pump to perform a predetermined operation, for example, as in claim 2, the pump is operated for a first predetermined time, and then the operation is terminated. Based on the fact that the pressure value after a predetermined period of time is less than or equal to the set value, the switching valve is switched from one container side to the other container side. Then, the determination unit determines that each container is empty or nearly empty based on the fact that the switching operation has been performed twice within another predetermined time period.

Therefore, according to the present invention, it is reliably and easily detected that both containers are empty or nearly empty, and based on this detection, the entire apparatus is stopped or a notification that the containers are empty is detected. Necessary measures can be taken, such as displaying or issuing warnings. Note that, as in claim 3, the set value related to the pressure can be determined in accordance with the predetermined remaining amount of each container, so even after it is determined that each container is empty or nearly empty, the pressure setting value can be set at least once. This has the effect that it is possible to supply only a small amount of liquid, which causes less inconvenience to the user, and also allows the equipment to have more time to replace the container.

[Brief explanation of the drawing]

[Fig. 1] Common configuration diagram of the first and second embodiments of the present invention

[Fig. 2] Flowchart showing the operation of the first embodiment

[Figure 3
] Partial flowchart that should be changed or added to FIG. 2 regarding the operation of the second embodiment

[Figure 4] Time chart of piping pressure commonly displayed for the first and second embodiments and the conventional example

[Explanation of symbols]

1 Container 2 Container 3 Case 4 Switching valve 5 Pressure sensor 6 Pump 7 Switching control section 8 Judgment section

Claims (4)

[Claims] 1. Two respective flexible containers in which a liquid is sealed;
a pump that is selectively connected via a switching valve and sucks and transports the liquid; a pressure sensor that measures pressure in piping between the pump and the switching valve; a point at which a predetermined operation of the pump ends; a switching control unit that switches the switching valve from the one container side to the other container side based on the fact that the pressure value after a predetermined time from An empty detection device for a liquid container, comprising: a determination unit that determines that each of the containers is empty or nearly empty based on the determination being made twice in a row within a predetermined period of time. 2. The device according to claim 1, wherein the predetermined operation of the pump is a suction operation for a first predetermined time. 3. The apparatus according to claim 1 or 2,
A liquid container empty detection device characterized in that a set value related to pressure is determined corresponding to a predetermined remaining amount of each container. 4. The empty detection device for a liquid container according to claim 1, wherein the liquid is an undiluted beverage solution used in a vending machine.