JP2004212268A - Residual amount detecting system by back-pressure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system capable of detecting individual residual amounts with one detector when detecting automatically the residual amounts using back-pressure, in the case where the residual amounts in containers are grasped exactly to issue an alarm in replenish and to execute automatic replenish control, when supplying a liquid from some of the containers as in a color changer for paint. <P>SOLUTION: A detecting tube for a detector inserted into a liquid to detect back-pressure of supplied gas so as to detect liquid level is arranged in each of the respective containers, the tube is connected to one supply passage for detection via an opening and closing valve, and the back-pressure in the detecting tube connected to the opening and closing valve opened by a controller is detected by a differential pressure detector to detect the residual amount. An operation valve is switched in order by the controller to detect the residual amount in each of the respective containers, and the alarm and the replenish control are executed by an output signal therein. The detection is stopped for a fixed time with a timer to allow the accurate detection, because the detecting pressure is unstable in the switching time. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the remaining amount of paint or the like contained in a container by a detection pipe inserted into a liquid, and detecting the remaining amount of a plurality of containers with one detecting device. And a system capable of controlling the amount of liquid.
[0002]
2. Description of the Related Art There are many methods for detecting the remaining amount of a container for storing a liquid when supplying the liquid, controlling the amount of use, and detecting the timing of replenishment. Are known. However, in paints, the level cannot be confirmed by the adhesion of color, and it is difficult to use an electrical detection device because many contain volatile and easily flammable solvents, and various proposals have been made by mechanical and physical methods. ing.
[0003]
In addition to methods using various level sensors that are explosion-proof used to facilitate electrical control, methods for measuring changes due to mass, methods for detecting position changes due to floats, etc. with magnet sensors, There have been proposed methods of detecting the load resistance of the rotating blades and replacing them with the remaining amount, but each has its own problems.
[0004]
In other words, if a sensor that detects the liquid surface position such as an ultrasonic sensor is used, it is necessary to provide explosion-proof treatment and it is troublesome to handle, and it is necessary to provide an expensive level detector in each container. There is a major problem in maintenance and the like for maintaining cost and accuracy and maintaining stable detection.
[0005]
Also, in the case of measuring the mass and measuring the amount as a representative characteristic thereof, or detecting the load resistance of the blade rotating in the liquid and replacing it with the remaining amount, the detection device itself is installed in each container in the same manner as described above. Must. There are various types of devices for measuring changes in mass, such as devices that measure the mass itself, and devices that measure the mass by converting it to pressure and use the converted value to measure the mass. In addition, there is a problem in that it is necessary to measure an uncertain element such as a container, which varies depending on the container, and has a problem of lack of accuracy.
[0006]
Further, when detecting the load resistance of the blade rotating in the liquid by using the viscosity of the liquid, similarly to the above, a device for measuring the viscosity by inserting a part into each container is incorporated, and the rotational load resistance is reduced. It is necessary to measure the change.
[0007]
On the other hand, when detecting the remaining amount of liquid containing a volatile solvent such as paint, safety should be considered first because of the danger of paint ignition and explosion. desirable. In other words, assuming that the liquid is subjected to pressure from the liquid surface with respect to its depth, the liquid surface is detected by inserting a tube into the liquid and continuously pushing out the gas from the opening of the liquid. There is known a method of detecting the depth of a liquid, that is, the remaining amount by detecting a necessary pressure corresponding to the depth.
[0008]
[Problems to be solved by the invention]
In the coating operation performed industrially, the supply of the coating material to the coating machine is important for automation, and it is an essential condition to control the coating material used. For this reason, various proposed improvements have been made as described above, but there is still room for improvement in each of the above-mentioned dangers that need to be eliminated with an electrical detection method that is considered easy to control. Especially at most painting sites, various paints are often used separately, and it is indispensable to have a device that can centrally manage multiple paint containers, and it is necessary to realize a device that can be used more easily and has higher reliability. Become.
[0009]
In the field of industrial coating, it is a highly safe and easy-to-use device. When supplying liquid from several containers, such as a color changing device for paint, the cost of each container can be reduced without increasing the cost of each container. There is a need for a system / apparatus capable of accurately grasping the amount and performing an alarm at the time of replenishment and performing automatic replenishment control to centrally manage the remaining amount of paint.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention arranges a detection pipe having an opening toward a bottom surface in a liquid container, and connects a means for supplying a back pressure detection gas to the detection pipe to continuously supply a trace gas. A device for detecting the back pressure when discharging the gas from the detection pipe by connecting a differential pressure detector to the supply passage and detecting a remaining liquid amount corresponding to the back pressure, A plurality of detection pipes branching from the supply passage and provided in a plurality of liquid containers via on-off valves are respectively provided, and one of these on-off valves is opened to detect a back pressure of gas to be supplied. And a control device for outputting a detection result.
[0011]
The detection pipe provided in each container is connected to a common differential pressure detector that detects the back pressure, and opens and closes the on-off valve only when the detection is necessary. The control device is controlled so as to open only one of the on-off valves that need to be detected.
The use of an electromagnetic on-off valve as a general-purpose on-off valve suitable for automatic control makes it possible to control the container to be detected by sending detection air from a safety zone to the detection pipe.
[0012]
In addition, by incorporating means and pressure switches that output the detection result of the detection pipe of one of the open / close valves in response to each display or control, the remaining amount of multiple containers can be individually checked, In addition, control of replenishment or the like can be performed based on the lower limit detection result.
[0013]
A further big feature is that when the on-off valve is switched, the means for stopping the detection for a certain period of time is incorporated in the control device, so that the supply gas performs stable discharge of bubbles from the detection pipe and the time until the correct back pressure is detected. As a result, the reliability of the detection control is improved.
In addition, by performing the plurality of detections sequentially and at regular intervals, it is possible to collectively manage the remaining amounts of many containers periodically with one differential pressure detector.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows a main configuration for carrying out the present invention. A paint container 1 is an open container, and the contained paint is exposed to atmospheric pressure. The container 1 is not limited to the size, shape and material, and can correspond to various containers. In the example of the figure, three containers (a), (b) and (n) are shown, but the number is not particularly limited. The detection pipe 2 for detecting the remaining amount provided in each container 1 has an opening 25 at the lower end, and is installed close to the bottom surface of the container 1 set as the lower limit E of the liquid level. A gas supply path 4 for detection is connected to the detection pipe 2, and is supplied from a compressed air source 3 through a filter 5 and a pressure reducing valve 6. The subscripts a, b, and c attached to the respective symbols indicate the symbols of the containers.
[0015]
The filter 5 is provided for cleaning so that impurities, generally water, oil and the like, are not fed into the paint, and the cleanliness is determined by the required degree of the liquid to be handled. The pressure reducing valve 6 is required to be an adjusting valve capable of stably supplying a pressure slightly higher than the maximum back pressure in consideration of the specific gravity of the liquid to be detected.
[0016]
The pressure to be supplied is about 5 kPa if the liquid has a specific gravity of 1 and the depth of 50 cm from the opening 25 is full, and the pressure for pushing out the air from the opening 25 of the detection pipe cannot be supplied for this back pressure. Must. The flow rate of the compressed air from the pressure reducing valve 6 is adjusted by the throttle valve 7 and sent to the detection pipe 2 from the connection pipe 19 via the electromagnetic valves 8 corresponding to the respective containers 1. The throttle valve 7 always fills the supply passage 4 with a pressure corresponding to the back pressure, and needs a minimum amount that can be sent out from the opening 25 of the detection pipe 2. If too much, the flow will occur and the back pressure will not be accurately measured. In the case of this example, the generation of bubbles is set at intervals of about one second.
[0017]
If the liquid to be handled is a volatile organic solvent and the paint has a risk of ignition, the above-mentioned solenoid valve 8 must be installed in a safe area away from a dangerous area such as a fire or explosion. The detection pipe 2 of the container 1 is connected with each connection pipe 19.
[0018]
The thickness and the material of the detection pipe 2 are not particularly limited, but a dimension is selected so as to obtain a stable discharge of bubbles due to the viscosity of the liquid to be detected. In the case of a paint, it is preferable to use a material that has a low adherence to the inner surface and has good cleaning properties. The detection pipe 2 is not limited, but as shown in FIG. 2, an opening 25 is determined at a lower limit position of the liquid by an appropriate fixing means 21 and fixed to the edge 23 of the container 1.
[0019]
A differential pressure gauge 11 in the control device 10 is connected to the supply passage 4 for sending the gas for detection. The differential pressure gauge 11 in this case detects a difference between the supply pressure and the atmospheric pressure, and uses a fine differential pressure switch or a pressure sensor for extracting an output signal. A pressure balanced with the pressure of the detection pipe 2 connected to any of the opened solenoid valves 8 is input to the differential pressure gauge 11.
In the case of the fine differential pressure switch, the lower limit of the paint container corresponding to the input pressure is detected when the fine differential pressure switch is operated, and a signal of a lower limit lamp or a buzzer is output when the remaining liquid becomes the lower limit. In the case of a pressure sensor, the result of the pressure input to the pressure sensor is subjected to a comparison operation with data set in advance by the comparison operation means 14, and a necessary output signal is output. Reference numeral 17 denotes a drive power supply for the control device.
[0020]
The output signal from the comparison / calculation means 14 can be used to activate an alarm or to indicate that the remaining amount is at the lower limit by the display means 15 for lighting a lamp. Also, the calculation result can be displayed as appropriate as the remaining amount of liquid based on the output value of the pressure sensor. Further, according to the output value, it is possible to control so as to start the supply of the liquid to the corresponding container 1 by outputting a supply start signal at the lower limit and to stop the supply at the upper limit.
[0021]
These control devices 10, together with the solenoid valve 8, can be easily installed at a location remote from the danger area depending on the liquid to be handled, so that safety can be easily achieved. In other words, when handling volatile organic solvents such as paints, the installation of electrical control equipment must be avoided or a completely explosion-proof specification must be used due to the danger of ignition or explosion of the solvent vapor. Safety can be ensured by a control device placed outside the danger zone D through piping.
[0022]
Further, the control device 10 is configured so that the switching control means 12 controls the opening and closing of each electromagnetic valve 8 so that the container 1 to be detected can be specified. In this embodiment, the solenoid valve 8 is a normally closed solenoid valve. In the example of FIG. 1, when the solenoid valve 8n of the container 1n is open, the air supplied through the throttle valve 7 is set to be open by the switching control means 12. It is discharged from the opening 25n through the connection pipe 19n and the detection pipe 2n.
[0023]
In the supply air, a pressure corresponding to the liquid pressure (back pressure) at the height of the liquid that has entered the liquid is maintained in the detection pipe 2n and the supply passage 4, and the pressure higher than the pressure becomes bubbles and the opening 25n of the detection pipe 2n. Will escape from The inside of the supply passage 4 is connected to a differential pressure gauge 11, to which the pressure of the detection pipe 2n is input.
At this time, the other solenoid valves 8a and 8b are closed, and the output signal is an alarm signal and a lamp as an output signal of the container (n) corresponding to the solenoid valve opened by the switching control means 12. . If the electromagnetic valve 8n is closed and the electromagnetic valve 8a is opened by the switching control means 12, the container 1a can be detected.
[0024]
That is, when the solenoid valve 8n is closed, the pressure in the supply passage 4 becomes the pressure sent from the pressure reducing valve 6 and the pressure of the differential pressure gauge also becomes the same pressure, but when the solenoid valve 8a is opened next, the supply air becomes the detection pipe 2a. And flows out of the opening 25a at the lower end as bubbles. Therefore, the pressure in the supply passage 4 becomes equal to the back pressure in the detection pipe 2a, and the differential pressure gauge 11 is detected as the pressure of the detection pipe 2a. As described above, the pressure detected by the differential pressure gauge 11 shows a correct value when the pressure in the pipe is balanced, and therefore, it is more preferable to detect the pressure after stabilization. Although this time may be practically no problem, it depends on the diameter and length of the pipe, the viscosity of the fluid to be measured, and the like. Therefore, by stopping the measurement for a certain period of time, an accurate display is always possible.
[0025]
If there is a problem if an incorrect output is temporarily output, such as when an alarm or other control signal is output based on the detection result, use a control device to stop detection for a certain period after switching. Thus, accurate detection can be performed.
[0026]
In this embodiment, the supply of gas to the detection pipe is selected by the solenoid valve. However, the supply to the container to be detected may be selected by a manual switching valve, and the result may be displayed as the remaining amount of the corresponding container. In addition, by linking the switching valve connected to the selected container and the display means provided for each container by the control device, the remaining amount of each container can be appropriately displayed.
[0027]
The control for opening and detecting the electromagnetic valve can be performed by a method using a changeover switch or a method of automatically repeating the order at a constant interval, whereby each container is sequentially detected, and the remaining amount can be easily managed. However, in the case where control for replenishment is added as described above by controlling the lower limit and the upper limit, control must be performed so that switching to the detection of another container is not performed during the replenishment time. The use of existing technology, such as a method of linking with other control programs, can extend the range of use as remaining paint management.
[0028]
【The invention's effect】
As described above, the present invention enables a gas required for measurement to be supplied via a valve provided individually to a detection pipe provided in a necessary container, and the back pressure thereof is individually detected by one detection device. In addition, it is sufficient to provide pipes and tubes for discharging gas to each container, and it is not necessary to equip individual containers with expensive detection equipment as in the past, and to detect the remaining amount of multiple containers.・ Economical management enables safe and easy-to-handle detection of residual amount even when handling paints and the like.
[0029]
In addition, the opening and closing control of the open / close valve by a solenoid valve installed outside the hazardous area together with the control unit facilitates automatic confirmation and management of each container, and enables the display and other control signals to be output to containers whose detection is being detected. Can be easily performed.
[0030]
Furthermore, when switching the detection of each container, there is a delay in the stability of the detection gas passage in comparison with the electric signal, but the display and the output of the signal to the outside are detected at the time of switching by means such as a timer. Can be reliably detected by temporarily stopping the power supply, and the reliability as the remaining amount detector can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of the present invention.
FIG. 2 is an explanatory view showing one embodiment of an attached state of a detection pipe according to the present invention.
[Explanation of symbols]
1, container 2a, 2b, 2c detection pipe 4 supply passage 5 filter 6 pressure reducing valve 7 throttle valve 8a, 8b, 8c solenoid valve 10 controller 11 differential pressure gauge 12 opening / closing control means 14 comparison processing 15 alarm 16 external output signal 19a , 19b, 19c Connection tube 21 Fixing means 25a, 25b, 25c Opening

Claims (5)

A plurality of detection pipes each having an opening directed toward the bottom surface in each of the plurality of liquid containers are arranged, and a means for supplying a back pressure detection gas to the detection pipe is connected to continuously supply a trace amount of gas, and the In a device for detecting a back pressure for discharging the gas by connecting a differential pressure detector to a main supply passage and detecting a remaining liquid amount corresponding to the back pressure, an on-off valve is provided for each supply passage of the liquid container. And a control device for detecting the back pressure of the gas to be supplied by opening any one of the on-off valves and outputting a detection result. The remaining amount detection system according to claim 1, further comprising a control device provided with a means or a pressure switch for controlling the opening and closing of the on-off valve by a control device and outputting a detection result of a detection pipe of one of the on-off valves corresponding to each opening. . 3. The remaining amount detection system according to claim 1, wherein a means for stopping detection for a predetermined time when the on-off valve is switched is incorporated in the control device. 4. The remaining amount detection system according to claim 1, further comprising a control for sequentially switching the on-off valve at a predetermined time interval. 5. The remaining amount detection system according to claim 4, further comprising a control for suspending the switching until replenishment is completed at the time of automatic replenishment.

Images