JPH0458074A - Syringe pump and its operating method - Google Patents

Abstract

PURPOSE:To restrain discharge speeds from fluctuating in e discharge process to a great extent by setting a syringe pump vertically, and thereby forming a gas layer between the front face of a piston and fluid surface. CONSTITUTION:A syringe pump is set vertically, and gas (air) A is sealed in a gap between the front surface of a piston 2 and fluid surface. In the second place, in the process of discharging fluid L, a cylinder 1 is lifted by a lifting means, the state of fluid surface is fixed at the time of discharge. By this constitution, discharging speeds are restrained from being fluctuated to a great extent in the process of discharge, the occurrence of fluctuation can thereby be prevented even with no accumulator furnished.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a syringe pump, and more specifically, a syringe pump in which a cylinder cylinder and a piston are arranged to be able to freely reciprocate relative to each other, and in which The present invention relates to a syringe pump in which a liquid suction path and a liquid discharge path communicate with each other.

[Conventional technology]

Various types of pumps are known, one of which is a syringe pump. As shown in FIGS. 1 and 2, a piston 2 is disposed within the cylinder tube so as to be able to reciprocate, and a liquid suction path 3 and a liquid discharge path 4 are communicated within the cylinder tube 1. This makes it useful as a metering pump.

Further, a suction valve 5 is provided in the suction path 3, and a discharge valve 6 is provided in the discharge path 4.
A sealing means 8 such as an O-ring is provided between the inner surface of the cylinder cylinder 1 and the outer surface of the piston 2.

In such a syringe pump, when the piston 2 is raised with the suction valve 5 open and the discharge valve 6 closed,
Since the inside of the cylinder tube 1 becomes negative pressure, the liquid to be supplied to the target region flows into the cylinder tube 1. When the predetermined amount of liquid has been suctioned, the suction valve 5 is closed,
When the piston 2 is lowered with the discharge valve 6 open, the liquid in the cylinder tube 1 is discharged and delivered to the target region. Such operations are performed intermittently.

[Problem to be solved by the invention]

However, in this type of syringe pump, it is essentially impossible to avoid pulsation during the discharge process, so it is necessary to install the accumulator 7 on the liquid outlet side.

This is especially essential when it is necessary to change the stroke of the piston in order to change the feed amount.

However, installing the accumulator 7 causes a rise in equipment costs and an increase in installation space, and should be avoided as much as possible.

On the other hand, liquid always enters the small gap between the outer surface of the piston 2 and the inner surface of the cylinder cylinder 1, so when dealing with liquids that are particularly viscous or highly adhesive, When liquid adheres and the amount of adhesion increases, it is necessary to disassemble and clean it. During this cleaning, the entire outer surface of the piston 2 that comes into contact with the liquid and the O
It is necessary to remove the ring 8 from the groove and clean it, which takes a lot of effort.

Therefore, in order to prevent pulsation even without an accumulator and to make the seal less dirty and easier to clean, the inventors of the present invention decided to seal gas between the front surface of the piston and the liquid surface, and to remove this gas. We found that it is effective to discharge the suctioned liquid through the pump, and confirmed that it actually leads to improved pulsation and cleaning performance.

However, as shown in FIG. 6, from the end of suction (al) to the discharge stage (bl), the liquid level changes and a head difference Δh occurs.When such a head difference occurs, the piston 2 is moved at a constant speed. As long as it is moved, the discharge amount will gradually decrease, making it impossible to obtain a constant discharge amount per unit time.

Therefore, an object of the present invention is to always obtain a constant discharge speed during one stroke so that, for example, when the liquid is used for coating, the amount of coating is uniform.

[Means to solve the problem]

The above problem is solved by a syringe pump in which a piston is disposed within a cylinder so as to be able to move relatively reciprocally, and liquid is sucked and discharged by moving the piston backward and forward, respectively. This can be solved by providing a gas layer between the front surface of the piston and the liquid level, and providing means for raising and lowering the cylinder tube.

In addition, during the operation, the problem can be solved by raising the cylinder cylinder during the discharge process to keep the liquid level constant during discharge.

[Effect]

Since the syringe pump of the present invention has a gas layer between the front surface of the piston and the liquid surface, mechanical unevenness during the relative movement process between the piston and cylinder cylinder during the liquid discharge process is absorbed in the gas layer. As a result, pulsation during feeding is reduced and installation of an accumulator is virtually unnecessary.

In addition, during the suction and discharge processes, a gas layer is interposed between the front surface of the piston and the liquid surface, so the piston does not come into direct contact with the liquid.
Therefore, the disassembly and cleaning cycle becomes long, and even if cleaning is necessary, the cleaning operation becomes easy.

On the other hand, especially in the present invention, during the liquid discharging process, the cylinder cylinder is raised to keep the liquid level constant at all times, so that a uniform discharge amount (discharge speed) per unit time is always obtained during the dispensing process. be able to.

[Specific structure of the invention]

Hereinafter, the present invention will be explained in more detail by way of specific examples with reference to the drawings.

In the present invention, it is not practically necessary to install an accumulator.

Moreover, especially in the present invention, as shown in FIG. 1, a gas layer A is secured between the front surface 2a of the piston 2 and the liquid level l. The gas used is not limited, but air is sufficient.

A cap IA having a suction hole and a discharge hole is removably provided on the lower surface of the cylinder cylinder 1, making it convenient for cleaning, and gas can be sealed by removing the cap IA. . IB is an outer cylinder that can be used as a holder.

In the conventional syringe pump configured as described above, the piston 2 was moved up and down to suction and discharge the liquid, but in the operation of the present invention, as shown in FIG.
This is done by moving the cylinder tube 1 up and down. Specifically, with the suction valve 5 open and the discharge valve 6 closed,
When the cylinder tube 1 is lowered, the inside of the cylinder tube 1 becomes negative pressure, so that the liquid to be supplied to the target area flows into the cylinder tube 1 through the suction path 3. When suction of a predetermined amount of liquid is completed, the suction valve 5 is closed and the cylinder tube 1 is raised with the discharge valve 6 opened, and the sealed gas layer A is compressed and the gas layer A is compressed. Due to the compressive force, the liquid in the cylinder tube 1 is gradually discharged and delivered to the target area. In this case, mechanical fluctuations (unevenness in the rise) in the rising process of the cylinder cylinder 1 relative to the piston 2 appear as pulsations in the feed liquid, but the compressible air
is present, the uneven rise is absorbed by the air A, thereby preventing pulsation.

During this discharge process, the O-ring 8 is in contact only with the gas layer A, and basically does not come into contact with the liquid until the lowering limit. Therefore, the cycle at the required point of cleaning is significantly extended,
Free yourself from the hassle of cleaning work.

In the example shown in FIG. 3, the liquid is sucked by lowering the cylinder l during the suction process, but the liquid is sucked by raising the piston 2.
During the discharge process, the cylinder cylinder l can be raised to make the liquid level the same as the liquid level at the end of suction.

As a means for raising and lowering the cylinder tube 1, as shown in Fig. 4,
For example, this can be done by screwing the cylinder cylinder 1 onto a ball screw IO, and rotating the ball screw IO with a forward/reverse motor 11.

Further, the formation positions of the liquid suction path 3 and the discharge path 4 are the fourth
It can be set as appropriate as shown in the figure and FIG.

4th rI! In example J, a liquid suction passage 3 is formed near the lower surface of the piston 2 of the cylinder cylinder I, and a discharge passage 4 is formed in communication with the center of the lower surface of the cylinder cylinder I.

In the example shown in FIG. 5, a suction passage 3 is formed at the center of the lower surface of the cylinder cylinder 1, and a discharge passage 4 is provided inside the cylinder cylinder 1 through the piston 2.

〔Example〕

Examples will be shown below to clarify the effects of the present invention.

When feeding a photosensitive material emulsion with a viscosity of 20 cps using a syringe pump with a cylinder barrel with an inner diameter of 50 g as shown in Figure 4, the liquid is sucked up to a maximum suction height of 100 mm while raising and lowering the cylinder barrel. and ejection was repeated. At this time, the amount of air enclosed was set to 75a/, and the pulsation was examined, and a pulsation rate of 0.65% was found.

In the case of the conventional example without an air layer, even if an accumulator was installed, the pulsation was about 5%, so it was found that the pulsation prevention effect was extremely large.

On the other hand, the flow rate fluctuation per unit time (corresponding to 1 minute - liquid level drop of 1.6 an) during - strokes was reduced to 1% or less, whereas it was 2.5% in the conventional case.

〔Effect of the invention〕

As described above, according to the present invention, fluctuations in discharge speed during the discharge process can be significantly suppressed. In addition, pulsation can be prevented even without an accumulator, and there are advantages such as less dirt on the seal and easier cleaning.

[Brief explanation of drawings]

FIG. 1 is a front half-sectional view of an example of a syringe pump of the present invention, FIG. 2 is a bottom view, FIG. Fig. 6 is a schematic diagram of an example of a syringe pump, and Fig. 6 is a schematic diagram of an operation example of a comparative example. 1...Cylinder tube, 2...Piston, 8...O
Ring, L...Liquid, A...Gas layer (air) Patent applicant Konica Co., Ltd. agent Patent attorney Yoshihisa Nagai +'i:': , -g Enji-11 Diagram (b) ◇

Claims (2)

[Claims] (1) A syringe pump in which a piston is arranged in a cylinder so as to be able to move relatively freely in a reciprocating manner, and in which liquid is sucked and discharged by retracting and advancing the piston, respectively, wherein the syringe pump is installed vertically, A syringe pump characterized in that a gas layer is provided between the front surface of the piston and the liquid surface, and a means for raising and lowering the cylinder tube is provided. (2) A syringe pump in which a piston is disposed in a cylinder so as to be relatively reciprocating, and liquid is sucked and discharged by retracting and advancing the piston, respectively, wherein the syringe pump is installed vertically; A method of operating a syringe pump, characterized in that gas is sealed between the front surface of the piston and the liquid level, and during the discharge process, the cylinder cylinder is raised to keep the liquid level constant during the discharge process.