JPH0445094B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid level measuring device suitable for centrally monitoring liquid levels in a plurality of reservoirs.

[Prior art and its problems] For example, in the coating process at an automobile factory, a plurality of reservoirs containing paint liquids of different colors are arranged, and each reservoir is provided with a circulation path to distribute the coating liquid. I'm trying to circulate it. A spray gun is connected to these circulation paths via a distribution tube, and when the trigger is operated, paints of various colors are sprayed onto the car body.

By the way, a guide tube is provided in each reservoir so as to be immersed in the coating liquid, and a gas such as nitrogen is sent from this guide tube into the coating liquid, pushing out the paint in the guide tube and creating air bubbles. The liquid level is determined based on the pressure inside the guide tube. For this reason, conventionally, each guide tube is guided to a pressure sensor via a measurement tube, so that the pressure values indicated by these can be measured. When the liquid level falls below a predetermined level, a suitable means such as a buzzer is used to issue an alarm, so that the shortage of paint liquid can be dealt with.

However, this method requires an expensive pressure-sensitive sensor for each reservoir, resulting in an inconvenience that increases the overall cost.

[Objective of the Invention] This invention has been made in consideration of the above, and its purpose is to provide a cost-effective method by providing a single pressure-sensitive sensor even though a plurality of liquid reservoirs are provided. It is an object of the present invention to provide a liquid level measuring device having excellent effects.

[Means for Solving the Problems] In order to achieve the above object, the present invention employs the following configuration.

The liquid level measuring device is placed in a workplace where the liquid in the container is consumed, and it selectively introduces gas from a plurality of liquid reservoirs that communicate the inside of the container with the outside air and a gas reservoir, and controls each of the above liquid reservoirs. A plurality of guide pipes that compare the liquid pressure near the bottom of the vessel with the pressure inside the pipes, a plurality of switching valves that connect each inlet to each of the above guide pipes via a respective measurement pipe, and each of these switching valves. The liquid in the liquid reservoir is determined based on the gas pressure in the measurement chamber at the time when the liquid pressure and the gas pressure in the guide tube are balanced. A single pressure-sensitive sensor that detects the surface level, and a pressure relief valve that performs an opening operation and releases the gas in the measurement chamber to the outside air every time the measurement of the liquid level in one liquid reservoir is completed. configured.

[Operation] Gas is introduced from the gas supply source into the guide pipe of the liquid reservoir whose liquid level is to be measured, the corresponding switching valve is opened, the pressure inside the guide pipe is increased, and the liquid pressure near the bottom is increased. Balance.

The pressure sensor detects the liquid level based on the gas pressure in the measurement chamber at the time when the pressure in the guide tube is balanced with the liquid pressure in the liquid reservoir whose liquid level is to be measured.

The pressure release valve performs an opening operation every time the measurement of the liquid level of one liquid reservoir is completed, and releases the gas in the measurement chamber to the outside air.

[Effects of the Invention] The liquid level measuring device of the present invention is advantageous in terms of cost because it suffices to provide a single pressure-sensitive sensor when measuring the liquid level of the liquid in each reservoir.

[Example] An example of the present invention will be described below based on the drawings.

For example, in a painting system in a paint shop used in automobile manufacturing, as shown in FIG. 1, reservoirs 1 to 7 containing paint liquids of different colors are provided. These reservoirs 1 to 7 are
The guide pipes 1a to 7a are immersed to the vicinity of the bottom, and the circulation paths 15 to 21 are extended to the outside by the supply pumps 8 to 14, and the back pressure valve 22
It returns to reservoirs 1 to 7 via channels 1 to 28. Three spray guns D1 to D3 are connected in parallel to each circulation path 15 to 21 via distribution tubes t1 to t3. Then, the paint in the reservoirs 1 to 7 is supplied to a supply pump 8.
to 14 and back pressure valves 22 to 28, it is circulated through circulation channels 15 to 21, and is applied to the body of the motor vehicle via a distribution tube t1, for example, by operating a spray gun D1.

Now, in this coating system, as shown symbolically on the right side of FIG. 1, for example, electromagnetic metering valves 29 to 35 are installed corresponding to the reservoirs 1 to 7. Each inlet of these metering valves 29 to 35 is connected to a gas supply device (gas supply source) 36 that supplies nitrogen gas, etc., and each outlet is connected to one end of T-shaped pipes 37a to 43a via supply pipes 29a to 35a. It is connected to the guide tubes 1a to 7a. From the other end of the T-shaped pipes 37a to 43a, measurement pipes 44a to 50 are connected.
It is connected to switching valves 44 to 50 via a.

These switching valves 44 to 50 are arranged in communication with each other on an aluminum case 51, as shown in FIGS. 2 and 3. This case 51 has a measurement chamber 51a inside, and a discharge port A corresponding to the switching valves 44 to 50 on its side.
These discharge ports A to G are connected to each other in communication at one end of the connecting tube 52, and the other end is attached to a pressure sensor 53. The pressure sensor 53 is made of, for example, a strain gauge, and is equipped with a display that digitally displays the deformation of the strain gauge using a transducer (not shown) for converting pressure and liquid level. 5
Reference numeral 4 denotes a pressure relief valve, which is attached to the case 51 so as to be in communication with the measuring chamber 51a through the pressure relief port 55 when opened.

As the painting process progresses, the paint liquid in the reservoirs 1 to 7 decreases. At this time, in the monitoring center, in order to check the condition inside the reservoir 1, for example, when the metering valve 29 is opened, the gas supply device 3 is opened.
6, nitrogen is first sent to the metering valve 29,
Here, it is controlled to several cc, and T
The liquid enters the guide pipe 1a through the shaped pipe 37a and generates bubbles in the coating liquid in the reservoir 1. Along with this, the switching valve 44 is also activated, whereby the pressure based on the bubbles in the coating liquid is transferred from the guide tube 1a to the measurement tube 44.
a, guided into the measurement chamber 51a via the switching valve 44, and then sent to the pressure sensor 53 via the connecting tube 52. As a result, the pressure based on the bubbles is converted into a liquid level in the reservoir 1, and its height dimension is measured and digitally displayed on the display. If the liquid level measured in this way is lower than a predetermined level, the amount of coating liquid is insufficient, and an alarm device such as a buzzer is used to notify the operator and make him/her take appropriate measures. After that, the pressure relief valve 54 is opened to release the pressure in the measurement chamber 51a from the pressure relief port 55.

Such operations are performed using metering valves 30, 31...35.
By sequentially applying these steps, the liquid level in the reservoirs 2, 3...7 according to the number of paint colors can be measured continuously and quickly, and the monitoring center can check whether the amount of paint liquid is normal or insufficient in the same way as above. can be confirmed.

Moreover, when measuring the liquid level in each reservoir, a single common pressure-sensitive sensor 53 is sufficient, unlike the conventional method in which each reservoir must be provided with an expensive pressure-sensitive sensor. It is advantageous in terms of cost.

In the above embodiment, seven reservoirs 1 to 7 were provided for each color of paint, but the number is not limited to this number and can be set to an appropriate number depending on the case. may be the same color rather than different colors. Furthermore, the pressure sensitive sensor 53 for measuring the liquid level is not limited to a strain gauge, but may be a mercury column or the like.

Furthermore, in the above embodiment, when measuring the liquid level, the metering valves were opened one by one depending on the desired reservoir, but with the gas supply device in operation, all metering valves were opened one by one depending on the desired reservoir. It may be configured such that the valve is opened in advance and only the switching valve needs to be operated when measuring the liquid level. Further, the metering valve may be configured to periodically repeat the opening operation in a predetermined order and at time intervals of about 5 seconds.

Further, in the above embodiment, nitrogen gas is supplied by the gas supply device 36, but the present invention is not limited to nitrogen gas, and non-flammable gas such as air may be supplied.

Furthermore, in the above embodiment, when there is a shortage of paint, a buzzer or the like sounds to notify the user, but an automatic supply device is installed to fill the reservoir each time the paint decreases and the situation becomes insufficient. New paint may be automatically supplied.

In addition, in the above example, paint was used as the liquid for level measurement, but aqua on ships
It can also be applied to measuring the amount of water in outdoor tanks, as well as the amount of gasoline in underground tanks at gas stations.

In addition, the object to be painted is not limited to the body of an automobile, but may also be applied to household electrical appliances or other appropriate devices.

In addition, various changes may be made in the specific implementation without departing from the gist of the invention.

[Brief explanation of drawings]

Figures 1 and 3 show one embodiment of the present invention, with Figure 1 being an overall painting system diagram, Figure 2 being a schematic diagram mainly showing the switching valve, and Figure 3 being similar to Figure 2. FIG. 3 is a side view of the switching valve taken along line X-X. In the figure, 1 to 7...Liquid reservoir, 1a to 7a...
Guide pipe, 36... gas supply device (gas supply source),
44-50...Switching valve, 44a-50a...
Measuring tube, 51... Case, 51a... Measuring chamber, 5
3...Pressure sensor, 54...Pressure relief valve.

Claims (1)

[Scope of Claims] 1. A plurality of liquid reservoirs arranged in a workplace where the liquid in the vessels is consumed and whose interiors are communicated with the outside air; and a plurality of liquid reservoirs in which gas is selectively introduced from a gas supply source to A plurality of guide pipes that compare the liquid pressure near the bottom of the vessel with the pressure inside the pipes, a plurality of switching valves that connect each inlet to each of the above guide pipes via a respective measurement pipe, and each of these switching valves. and a common measurement chamber to which each outlet of the liquid reservoir is connected, and the liquid in the liquid reservoir is measured based on the gas pressure in the measurement chamber at the time when the liquid pressure and the gas pressure in the guide tube are balanced. A single pressure-sensitive sensor that detects the surface level, and a pressure release valve that performs an opening operation and releases the gas in the measurement chamber to the outside air every time the measurement of the liquid level in one liquid reservoir is completed. A liquid level measuring device consisting of: