JPH10307051A - Constant-quantity discharge apparatus for liquid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a constant-quantity discharge apparatus which can prevent generated air bubbles inside a syringe from flowing into a discharge pipe line by a method wherein a rod seal is installed also on the side of a piston rod at the syringe and a relief groove which is larger than the outside shape of an O-ring is formed in the inrush upper end of a piston. SOLUTION: A liquid is filled into the side of a piston rod 6 at a syringe 2. A three-way selector valve 16 is changed over to the open-circuit side of a syringe nozzle. When a piston 4 is lowered, a liquid is discharged from a nozzle 20. Generated air bubbles float, they are collected on the rear surface of the piston 4, and they do not flow into a nozzle pipe 19. After they are discharge repeatedly and when the influence of the collected air bubbles cannot be regulated, the three-way selector valve 16 is changed over to the open-circuit side of a syringe tank. The piston 4 is raised, a liquid is sucked, the piston 4 is rushed into a relief groove 3 at the upper end, and the air bubbles 4 are passed through the gap between the outer circumference of an O-ring 5 at the piston 4 and a large-diameter groove so as to be discharged to the side of a tank 18. After that, the piston 4 is returned a little, the relief groove 3 is closed, and the three-way selector valve 16 is changed over to the open-circuit side of the syringe nozzle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[Industrial application] A quantitative discharge device for dispensing, applying, and injecting a highly volatile liquid such as a liquid such as acetone, methyl ethyl ketone, or chlorofluorocarbon or a mixed liquid.

2. Description of the Related Art A three-way valve for switching the interior of a syringe to communicate with a discharge nozzle or a tank is provided at the top discharge port of a single-acting syringe like a syringe. In a fixed-rate discharge device that switches the three-way valve to communicate with the tank at the time of retreat and draws the liquid into the syringe, when discharging a small amount of a liquid such as acetone, methyl ethyl ketone, or chlorofluorocarbon or a mixed liquid, The large liquid generates small bubbles in the syringe, grows, becomes bubbles of a visible size, collects at the top of the syringe, and is discharged to the nozzle side with the flow of the liquid. In the case of a very small amount of discharge, the size of the bubble is not negligible, and the discharge accuracy is deteriorated, or an idling phenomenon occurs. Bubbles that remain in the syringe or in the pipeline cause poor liquid discharge at the time of discharge and cause dripping. In an automatic injection machine or an automatic coating machine, the influence on the performance function of the machine is large.

[Problems to be Solved by the Invention] A pipeline for discharging bubbles is provided, and bubbles generated in the syringe are not allowed to flow into the discharge pipeline.

[Means for Solving the Problems] A rod seal is also provided on the piston rod side of the syringe to provide a liquid filling space and a liquid in / out port. A three-way switching valve is connected to the access port so that the port can be switched to a discharge nozzle pipe or a tank pipe. A relief groove larger than the outer shape of the O-ring sealing the inner surface of the syringe is formed at the upper end of the piston of the single-acting syringe, and a liquid inlet / outlet port is provided at the upper part to communicate with the tank line. The syringe stands upright with the piston side up, and the tank is placed above the syringe or a pressure gas is introduced into the tank to apply pressure to the liquid.

[Operation] The piston rod side of the syringe is filled with liquid, and the three-way switching valve is switched to the syringe ... nozzle open side. When the piston is lowered, liquid is discharged from the nozzle. The generated bubbles float upward, collect on the lower surface of the piston, and do not flow into the discharge nozzle pipe. When the effects of the air bubbles collected after repeated discharge can no longer be ignored, the three-way switching valve is switched to a syringe ... tank open side, and when the piston is moved upward, liquid is sucked in, and the piston enters the escape groove at the upper end, Bubbles are discharged to the tank line through a gap between the outer periphery of the O-ring of the piston and the large-diameter groove. When the air bubbles are discharged, return the piston a little and close the escape groove. Next, the three-way switching valve is switched to the syringe... Nozzle opening side.

[Effect] Since the generated bubbles do not flow into the nozzle pipe side, high-precision discharge can be ensured. Generated bubbles can be discharged to the tank side, eliminating the need for a drain tank. Since air bubbles are removed simultaneously with the inhalation of the liquid, almost no time is required. Only a slight extension of the piston stroke, the formation of a relief groove in the syringe and the programming of the control are simple and cost-effective.

[Embodiment 1] A liquid metering apparatus 1 includes a discharge head 8 to which a syringe 2 is fixed and a piston rod 6 moves in and out, a three-way switching valve 16 connected to a lower port of the syringe 2, and a three-way switching valve 16. The driving device 21, the tank 18 installed above the syringe 2, and the controller 14 that controls the movement of the pulse motor 10 for driving the ejection head 8 are configured as main components. Syringe 2 at the top
The relief groove 3 having a groove diameter larger than the outer diameter of the O-ring 5 of the piston 4 is formed. A rod seal 7 of a piston rod 6 is attached to the lower end of the syringe 2 and a liquid chamber is formed below the piston. A tank port 22 is provided at an upper end of the relief groove 3 and communicates with an upper part of the tank 18 by a drain pipe 23. A liquid inlet / outlet port 24 is provided at the lower end of the syringe 2 and communicates with the three-way switching valve 16 and the valve pipe 17. The tank side of the three-way switching valve 16 communicates with the tank 18 through the tank pipe 15, and the nozzle side communicates with the nozzle 20 through the nozzle pipe 19. The ejection head 8 guides the pusher 9, and is driven by a pulse screw 10 by a feed screw 11.
As a result, the pusher 9 reciprocates. The piston rod 6 is fixed to the pusher 9, and reciprocates with the pusher 9 so as to protrude and retract into the syringe 2. A lower end sensor 12 and an upper end sensor 13 for detecting the lower end and the upper end of the pusher 9 are attached to the ejection head 8. Valve drive 21
Controls the switching drive of the three-way switching valve 16 by the controller 14.
This is performed under the control of The three-way switching valve 16 is the valve piping 1
Valve driving device 21 so that nozzle 7 and nozzle pipe 19 communicate with each other.
When the pulse motor 10 rotates forward and the pusher 9 is lowered, the piston 4 is also pulled downward, and the liquid in the syringe 2 is discharged from the nozzle 20. While the pusher 9 gradually descends and repeats the minute discharge, bubbles are generated in the syringe 2 and gather on the lower surface of the piston 4.
When the lower end sensor 12 detects the pusher 9, the controller 14 issues a command to the valve driving device 21 to drive the three-way switching valve 16, the valve pipe 17 and the tank pipe 15.
Communication. Next, the controller 14 reverses the pulse motor 10, the pusher 9 pushes the piston rod 6 upward, and the liquid in the tank 18 flows into the syringe 2. When the pusher 9 further rises, the piston 4 enters the escape groove 3 and stops upon detecting the upper end sensor 13.
When the piston 4 enters the escape groove 3, the O-ring 5 stops operating, and the liquid flows into the drain pipe 23 through the outer periphery of the piston 4. At this time, the air bubbles collected at the lower part of the piston 4 are washed away and discharged to the drain pipe 23. At this time, when the pulse motor 10 is rotated in the normal and reverse directions to reciprocate the piston 4 in the relief groove 3, small bubbles trapped on the lower surface of the piston are pulled apart, and the discharge is easily performed. Next, the controller 14 is the pulse motor 1
0 is rotated forward, the piston 4 is pulled down, and escapes from the escape groove 3. Next, the three-way switching valve 16 is switched by the valve driving device 21 to communicate the valve pipe 19, and a series of operations is completed. Several kinds of programs in a necessary operation order are incorporated in the controller 14 in advance, and a required operation is given by a select function. The operation sequence is fully automatic. Discharge is performed according to a command from an external control device such as a sequencer. Discharge single action: Discharges by operating a manual button. Bubble removal: Performs bubble removal operation. Fluid drain …… Drain the liquid in the syringe and pipeline. Cleaning ……… Clean tanks, syringes and pipes. Filling liquid …… Fill the syringe with liquid. If the required programs are selected and operated by incorporating the programs in the above operation order, the handling of the ejection device 1 is simplified.

[Embodiment 2] The discharge device 30 of the embodiment 2
The ejection head 8 is common to the first embodiment. Syringe 31
Is a cylindrical piston 3 whose diameter is slightly smaller than the inner diameter of the syringe.
2 is sealed with a piston seal 33 at the lower end. The upper end port 34 of the syringe 31 communicates with a liquid supply valve 35, and the lower end port 36 communicates with a discharge valve 37.
The liquid supply valve 35 communicates with the tank 38 and the discharge valve 37
Communicates with the nozzle 39. Both the liquid supply valve 35 and the discharge valve 37 are driven by driving devices 40 and 41, respectively, with two-way switching valves that open or close the pipeline. Discharge valve 3
When the pipe 7 is opened and the liquid supply valve 35 is closed, and the pusher 9 pushes the cylindrical piston 32 into the syringe 31, the liquid inside is discharged from the nozzle 39. Syringe 3
Air bubbles generated in 1 collect at the upper part of the syringe. Next, when the discharge valve is closed and the liquid supply valve 35 is opened, the air bubbles float to the tank side and are discharged. When the pusher 9 is lowered and the cylindrical piston is pulled back, the liquid in the tank 38 is sucked into the syringe 31. The liquid supply valve 35 is closed, the discharge valve 37 is opened, and a series of operations is completed. In the case of the syringe 31, the seal is a piston seal 33.
Only the resistance is small, and there is a gap between the inner surface of the syringe and the outer periphery of the cylindrical piston 32. Therefore, it is possible to adapt to a liquid mixed with ceramic powder or the like without causing biting. When both the liquid supply valve 35 and the discharge valve 37 are opened, the liquid in the tank 38 easily flows to the nozzle 39, so that the internal cleaning is simple. There is also a mixture such as silver powder,
In the case of a liquid that needs to be constantly stirred, the liquid is always stirred in the tank 38, and the volume of the syringe 31 is set to a minimum necessary.
As soon as the life time of the liquid elapses, the liquid in the syringe is discharged, and a new liquid can be easily introduced from the tank and used.

[0009]

[Brief description of the drawings]

FIG. 1 is a simplified cross-sectional view of a first embodiment of the present invention.

FIG. 2 is a simplified cross-sectional view of Embodiment 2 of the present invention.

[Explanation of symbols]

1, fixed-quantity discharge device 2, syringe 3, relief groove
4, piston 5, O-ring 6, piston rod 7, rod seal 8, discharge head 9, pusher 10, pulse motor 11, feed screw 12, lower end sensor 13, upper end sensor 14, controller 15, tank piping 16,
Three-way switching valve 17, valve piping 18, tank 19, nozzle piping 20, nozzle 21, valve driving device 22, tank port 23, drain piping 24, access port

Claims (1)

[Claims] A rod seal is also provided on the piston rod side of the syringe to provide a liquid filling space and a liquid inlet / outlet port. A three-way switching valve is connected to this inlet / outlet port so that the port can be switched to a discharge nozzle line or a tank line. A relief groove larger than the outer shape of the O-ring sealing the inner surface of the syringe is formed at the upper end of the piston of the single-acting syringe, and a liquid inlet / outlet port is provided at the upper part to communicate with the tank line. The syringe is vertically set with the piston side up, and the tank is placed above the syringe, or a pressurized gas is introduced into the tank to apply pressure to the liquid to discharge the liquid.