JPS6176770A - Liquid delivery system - Google Patents

Abstract

PURPOSE:To lower the pressure withstanding performance of conduit while to reduce usage of compressed air by controlling the pressure of air pressure source for air pressure cylinder for driving a pump for pressure feeding the liquid with correspondence to the pressure in delivery line. CONSTITUTION:A pump 1b for delivering liquid such as sealant, adhesive,paint, etc. is provided. Said pump 1b is driven through a pneumatic cylinder 1a. Compressed air is fed through a changeover valve 1d into said cylinder 1a. While an air pressure source 8 is coupled with high and low pressure air supply paths 9, 10. Reducing valves 9a, 10a and control valves 9b, 10b for regulating respective pressure are arranged in respective path 9, 10. Respective supply path 9. 10 is coupled through said control valves 9b, 10b to the changeover valve 1d. Said control valves 9b, 10b are controlled by the pressure in the delivery line 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for pumping and discharging a liquid, such as a coating line having a large number of discharge nozzles for applying a sealant, adhesive, paint, etc. used for.

(Prior art and its problems) Fig. 2 shows a liquid discharging device for a coating line that centrally supplies liquid such as sealant, adhesive, or pigment from one place, and shows a pressure feeding device 1 that pumps the liquid. , a main pipe line 2 connected to the pumping device 1, and a large number of branch pipe lines 3 branched to the main pipe line 2. Pressure feeding device 1
is a pump 1b reciprocally driven by, for example, a pneumatic cylinder 1a, and pumps liquid Q in a tank 1c by 150 to 20
It is pumped at a pressure of about 0 kg/cnl. The pneumatic cylinder 1a receives a supply of compressed air from a pneumatic source 4 at a constant pressure, and is alternately sent into the cylinder chamber by a switching valve (not shown). Therefore, the pneumatic cylinder 1a is configured to have the effective area of its piston and the supplied air pressure. The pump 1b is driven with a constant driving force according to the pressure and flow rate, and the liquid is sent into the main pipe 2 at a pressure and a flow rate corresponding to the driving force. Each branch pipe line 3 has a regulator 5 for adjusting pressure,
An opening/closing valve 6 and a discharge lower are provided, and the opening/closing pulp 6 is opened as necessary to discharge liquid from the discharge lower for use. 2a is a pressure gauge.

In such a liquid discharging device, although the liquid pumping capacity of the pumping device 1 is constant, the total amount of liquid used to be discharged from each discharge lower varies over time, so there may sometimes be a shortage of liquid supply. This can sometimes lead to a situation in which the pressure in the main line 2 becomes very high. In order to prevent this, the pressure of the air pressure source 4 must be made as high as possible, and the pressure resistance of the main pipe line 2 and branch pipe line 3 must be made high, which increases the equipment cost of the pipe line and increases the pressure. , the amount of compressed air used will also increase.

(Means for Solving the Problems) The present invention has been made to solve the above-mentioned problems, and it eliminates the need to increase the withstand pressure of the pipelines more than necessary, and eliminates the need to use compressed air in vain. It is an object of the present invention to provide a liquid discharging device that does not have to be A large number of connected branch pipes, a plurality of air supply pipes with mutually different pressures for supplying compressed air to the pressure feeding device, and a plurality of air supply pipes provided in the main pipe to detect the pressure of the liquid in the main pipe. a pressure detector, and when the pressure detector detects a pressure lower or higher than a preset certain tolerance range, the air supply path is set to a higher or lower pressure among the air supply paths; It is characterized in that it is controlled to selectively switch and connect.

(Example) The present invention will be described below based on an example with reference to the drawings.

In FIG. 1, parts having the same functions as those explained in FIG. 2 are designated by the same reference numerals, and their explanation will be omitted.

A high-pressure air supply path 9 and a low-pressure air supply path 10 for supplying compressed air to the pressure-feeding device 1 are branch-connected to the air pressure source 8, and these are connected to a switching valve ld of the pressure-feeding device 1. The high pressure air supply path 9 and the low pressure air supply path 10 include
Pressure reducing valves 9a and 10a and control valves 9b and 10b are provided, respectively, and the pressure is adjusted to about 5 kg/cnt or 3 kg/crA, respectively, by the pressure reducing valves 9a and 10a, and either of the pressures is adjusted by the control valves 9b and 10b. One side is selectively connected.

The main pipe 2 has a pressure gauge 11 that can be set to output a signal when the upper or lower limit of a certain pressure range is exceeded.
is provided, and the output of this pressure gauge 11 is transmitted to the control device 1.
2, and is connected so that the output of the control device 12 selectively opens and closes the aforementioned control valves 9b and fob.

When the pressure gauge 11 detects the upper limit value, the control device 12 opens the control valve 10b and connects the low pressure air supply path 10, and when the lower limit value is detected, the control device 12 opens the control valve 9b and connects the high pressure air supply path 9. The state is maintained until the lower limit value or upper limit value is detected, respectively, and only one of them is always connected to the pressure feeding device 1.

For example, the pressure gauge 11 is connected to the main pipe 2 when the low-pressure air supply line IO is connected and all the on-off valves 7 are closed.
The upper and lower limit values are set at constant values around the pressure of The pressure shall not be lower than the minimum pressure required to supply the required amount of liquid to the

To explain the operation of the liquid discharge device configured as described above, it is assumed that the control valve 10b is opened by the control device 12, the low pressure air supply path 10 is connected, and all the on-off valves 7 are closed. , it is assumed that the on-off valves 7 are opened from this state and the number of on-off valves 7 increases. Along with this, the pressure inside the main pipe 2 decreases, and the pressure gauge 1
When it drops to the lower limit set to 1, a signal is output,
The control device 12 closes the control valve 10b and opens the control valve 9b, and the high pressure air supply path 9 is connected. This causes the pressure within the main pipe 2 to rise and return to within the set range. Next, as the number of opened on-off valves 7 decreases, the pressure in the main pipe 2 increases, and when the pressure rises to the upper limit set on the pressure gauge II, a signal is output, and the control device 12 is closed, the control valve 10b is opened, and the low pressure air supply path 10 is connected. This reduces the pressure within the main pipe 2 and returns it to within the set range. Therefore, even if the number of opening/closing valves 7 that are opened changes and the total amount of liquid used changes, the pressure in the main pipe 2 and branch pipe 3 will always be maintained within a certain range, and the pressure from the discharge lower will always be maintained within a certain range. The occurrence of a situation in which the amount of liquid supplied is insufficient is prevented, and the situation in which the pressure in the main pipe line 2 and the branch pipe line 3 becomes abnormally high beyond the permissible value is also prevented. Further, when the amount of liquid used is small, low pressure air is supplied to the pressure feeding device 1, so compressed air is not consumed unnecessarily.

In the above-described embodiment, a pneumatic cylinder 1a is used as the pressure feeding device 1, but a pneumatic motor may also be used. Control valves 9b, 10
b may be separate or a single valve may be used to switch between the two supply channels 9.10. Instead of the pressure gauge 11, a strain gauge or a pressure sensor using a semiconductor pressure sensitive element and an amplifier may be used. The control device 9 can be a relay, a sequencer, or a microcomputer.

(Effects of the Invention) As described above, according to the present invention, it is possible to prevent insufficient supply even if the total amount of liquid used from each discharge port changes, and even if the amount used is small, the main pipe Since the pressure within the branch pipe can be suppressed from becoming abnormally high, the pressure resistance of the pipe can be lowered accordingly, and equipment costs can be reduced. Furthermore, the amount of compressed air used can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a liquid ejection device which is an embodiment of the present invention;
FIG. 2 is a circuit diagram of a conventional liquid ejection device. Q...liquid, 1...pressure feeding device, 2...main pipe, 3
... Branch pipe line, 9... High pressure air supply line (air supply line), 10... Low pressure air supply line (air supply line), 11.
...Pressure gauge (pressure detector), 12...Control device. Applicant Sunstar Giken Co., Ltd. Figure 2

Claims (1)

[Claims] A pressure-feeding device operated by air pressure to pump liquid, a main pipe connected to the pressure-feeding device, a large number of branch pipes connected to the main pipe, and an interconnection system for supplying compressed air to the pressure-feeding device. has a plurality of air supply channels with different pressures, and a pressure detector provided in the main pipeline to detect the pressure of the liquid in the main pipeline, and the pressure detector is lower than a preset certain tolerance range. Alternatively, when a high pressure is detected, an air supply path set to a higher pressure or a lower pressure among the air supply paths is controlled to be selectively connected.