JPS61178571A - Liquid feeding pump - Google Patents

Abstract

PURPOSE:To make the mixing ripple min. by making the pressure in a pump chamber equal to the outside pressure when switching to the process in which the third pump chamber which inhales the liquid discharged from the first and the second pump chambers according to a prescribed variation of the mixing ratio discharges said liquid outside is performed. CONSTITUTION:Plungers 9A and 9B are moved in reciprocation in the first and the second pump chambers 10A and 10B by the movement of the first and the second cams 1A and 1B. The liquid discharged from the both pump chambers join in the third pump chamber 10c. The both cams 1a and 1b are operated according to the variation of the mixing ratio of two liquids, and the preparatory compression state is generated, and when switching to the process in which the liquid in the third pump chamber is discharged outside is performed, the pressure of the liquid in the pump chamber is made equal to the outside pressure. Therefore, the mixing ripple becomes min., and two liquids are mixed according to the variation of a prescribed mixing ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid pump device with excellent quantitative performance and reproducibility.

[Prior art] In liquid chromatography, in order to elute multiple components with different properties at high speed while maintaining a high resolution, a solvent is developed by gradually changing the mixing ratio of two or more solvents with different properties. Gradient method is used.

In this method, for example, one pump is used, and on the suction side of the pump, incoming A is sucked in through a switching valve that is switched over time depending on a predetermined mixing ratio.

There is a method of mixing B solvent in a mixing chamber, but in order to improve the mixing effect, the mixing chamber must be made larger, which increases the dead volume and reduces quantitative performance and reproducibility. Resulting in.

Another method is to use two pumps, one for suctioning solvent A and one for suctioning solvent B, and mixing the most A and B solvents sucked by each pump on the output side according to a predetermined mixing ratio. However, the double plunger type pump used as a conventional constant flow liquid transfer pump has the following problems.

That is, the amount of outflow per unit time from the flow path of the first pump chamber (or second pump chamber) to the outside drops for a short time immediately after the suction process changes to the discharge process. This phenomenon occurs because the pressure in the pump chamber is close to zero during suction, and when the pump transitions to the discharge process, the pressure attempts to reach high pressure due to the movement of the plunger.
Since pressure is applied to the discharge side, the pressure in the outflow path outside the pump chamber cannot be overcome immediately, and until the pressure is exceeded, no liquid is discharged from the pump chamber to the outflow path, even if the cam or plunger is displaced. It is caused by something. This phenomenon is particularly noticeable when high pressure is applied to the outflow path outside the pump chamber.

[Problems to be Solved by the Invention] Now, there is an idea to improve the accuracy of constant flow performance with respect to withstand pressure by varying the period of the pump stroke (period of displacement of the plunger). That is, if the period of the pump stroke is made smaller, the degree of decrease in the flow rate per unit time will be increased, and if the period of the pump stroke is increased, the degree of decrease in the flow rate will be decreased. By increasing the flow rate, the degree of decrease in pressure-resistant flow rate per unit time is reduced. However, when the pump stroke is increased, the pressure constant flow performance per unit time is improved, but the smaller the flow rate is, the larger the pressure ripple becomes. For example, when sending liquid at a rate of 70-rate of about 11 IIQ per minute or higher, the liquid sending port does not decrease much with respect to a predetermined amount, the pressure constant flow resistance does not decrease, and the ripple is small. However, Q per minute, 1txQ
When sending liquid at the following flow rate, the ripple cycle of the pump becomes as long as about 1 minute, and even if a damper is used, the ripples cannot be smoothed out.

Therefore, in systems where two or more types of liquids are mixed using such a constant flow pump, such as in gradient elution, when the stroke is increased as described above, the two When liquids are mixed based on a continuously changing mixing ratio, the two liquids are not mixed at a predetermined mixing ratio due to mixing ripples, resulting in poor quantitative performance and reproducibility.

The present invention aims to solve such problems and provides a novel liquid feeding pump device.

[Means for Solving the Problems] The solvent gradient device of the present invention has a first cam and a second cam that operate synchronously by a common cam drive mechanism. First plunge in the second pump chamber 17. The second plunger is linearly reciprocated, and the first plunger is moved in accordance with a predetermined mixing ratio change from the outside. Suction of liquid into the second pump chamber and the first
．． discharging the liquid from the second pump chamber to the third pump chamber, and moving the third plunger linearly back and forth within the third pump chamber by the movement of a cam operated by an independent cam drive mechanism;
The liquid discharged by the first pump chamber and the second pump chamber is sucked into the third pump chamber, and the liquid is discharged to the outside by movement of the third plunger. The pressure inside the pump chamber is made to be the same as the pressure outside when switching to the step of discharging the liquid to the outside.

[Operation] According to the predetermined mixing ratio change in the previous step, the first. If the pressure inside the pump chamber is the same as the external pressure when the third pump chamber sucks the liquid discharged from the second pump chamber and switches to the step of discharging the liquid to the outside, the third plunger When the pump begins its movement for discharge, there is no time required to make the pressure of the liquid in the third pump chamber the same as the pressure outside the chamber, so there is no delay in the discharge of the liquid. , the liquid flows from indoors to outdoors, and the amount of flow per unit time from the flow path to the outside does not drop. Therefore, the mixing ripple is minimized,
The two liquids are mixed according to a predetermined mixing ratio change.

[Embodiment] FIG. 1 is a schematic diagram of a liquid pump device showing an embodiment of the present invention.

In the figure, 1A and IB are identical 1st. a second cam, and the shaft of each cam has a first cam of the same shape. Second gears 2A and 2B are attached. The rotation directions of the first cam and the second cam are opposite to each other, and by rotating at the same time, the first cam and the second cam are formed into a shape having displacement characteristics with equal absolute values of curvature and opposite signs. 3 is a third gear that meshes with the two gears, and the shaft 4A of this gear is fixed to the shaft of the first motor 5A. 6 is a first pulse generator that generates a pulse signal according to a command from the control device 7 and transmits it to the first motor 5.
Supply to A. Also, the first cam.

The second cam has the first. The 20th-ra 8A and 8B are in contact. Part 1. The 20th-ra each has the 1st. Second plungers 9A and 9B are connected. The first and second plungers rotate in synchronization with the rotation of the motor. Second
The movement of the cams 1A and 1B causes the first. It performs linear reciprocating motion within the second pump chambers 10A and 10B. 10G is the discharge passage OA of the first pump' [10A and the second pump chamber 10B.
This is a third pump chamber having a suction passage IC connected to a place where it joins the discharge passage OB. 9G, 8C, and IC are third respectively.
These are the plunger, the 30th-ra, and the 3rd cam. The shaft 4B of the third cam is connected to the shaft of a second motor 5B, and the second motor is driven through a second pulse generator 6B.
It operates according to instructions from the control device @7. b in the diagram
l*b2+b3+bi, bs, and bg are balls that float or sink in the liquid path according to the movement of each plunger to flow or stop the liquid. Also, 11A,
11B.

11C are each of the above-mentioned No. 1. Second. Third plunger 9A, 9
B, 9G as the first. Second. This is a compression spring that is brought into contact with the third cam. 12A and 12B are suction passages IA of the first pump and the second pump, respectively.

These are A liquid tank and B liquid tank connected to I8. In the pump device, the third plunger 9C has a function of discharging liquid to the outside, and the third plunger 9C has a function of discharging liquid to the outside. The second plungers 9A and 9B have the function of sending suitably pressurized liquid to the third pump chamber 10G.

The operation of the constant flow liquid transfer pump configured in this manner will be described next.

The control device 7 sends a command signal regarding the rotation angle of the cam corresponding to the )O-rate in advance to the pulse generator 6A.

I'll send it to 6B. That is, if the 70-rate is smaller,
The rotation angle of the cam is decreased accordingly, and if the flow rate is large, a signal is supplied that increases the rotation angle of the cam accordingly. Then, the cam is repeatedly rotated alternately to the left and right at the selected rotation angle. In this case, for example,
When rotating clockwise, a suction process is performed, and when rotating counterclockwise, a discharge process is performed.

Furthermore, although the first cam 1A and the second cam 1B rotate in opposite directions, they perform suction and discharge operations in synchronization. The operation of these two cams is performed, for example, in accordance with a change in the mixing ratio due to mixing of the two liquids as shown in FIG. That is, the operation of the first cam causes the first pump chamber 10A to suck in or discharge liquid A according to the liquid level line L1 in FIG. 2, and the second pump 110B synchronizes with the liquid level line L1 in FIG. Inhale or discharge B liquid according to L2. Therefore, a mixed liquid having a value obtained by mixing liquid A in an amount according to Ll and liquid B in an amount according to L2 is discharged into the suction path IC of the third pump chamber 10G. In this liquid mixture, the mixing ratio of liquid A and B1ff1 gradually changes, but the amount is always constant. As shown in FIG. 3, the first cam 1A and the second cam 1B are used to perform this operation. The first cam 1A has a displacement of Ya=kX2, and the second cam has a displacement of Yb=k (c - ) has the characteristic of having a displacement of 2. In FIG. 3, Y is displacement and X is cam position. In this case, the first cam rotates to the left and to the right through a rotation angle corresponding to the flow rate, and the second cam rotates to the right and to the left through the same angle. In the figure, the range of change in the cam position corresponding to the rotation angle is represented by ΔX. This cam position change range ΔX is constant unless the 70-rate changes, but the mixing ratio of liquid A and liquid B is
In order to change the position as shown in the figure, the control device 7 gives a command to the first pulse generator 6A to gradually change the operating position of the cam. That is, the first pulse generator changes the number of driving pulses to the first motor 5A slightly between forward and backward according to the command from the control device.

Now, referring to FIG. 3, the operations of the first cam and the second cam will be explained. The first cam for the minute change ΔX of the second cam. The moving distance (i.e., the discharge amount) of the second plunger is d Y a / dx = 2 kx...
(1) dYb/dx=2k (c-X)
・−・−(2>If the first pump and the second pump are considered as one liquid compression pump discharging to the third pump, the moving distance is the sum of (1) and (2) above, It becomes constant at 2kC.

The discharge rate ratio of the first pump and the second pump is Ya'/Yb'=x/(c-x)=(
3), and the discharge amount ratio of the first pump and the second pump is
= OrO: C, -...-...-, X = O/2 and 1
=1゜・・・・・・・・・COO at X-C, and by changing the cam position X to Q-c over time, it is discharged to the suction path IC of the third pump chamber. Solvent A,
The mixing ratio of B can be changed as specified.

Figure 4 shows the operation diagram of the composite plunger and the third plunger when the combination of the first pump and the second pump is considered as one pump, where the horizontal axis is time and the vertical axis is the upward direction. indicates the discharge amount, and the downward direction indicates the suction amount. In the figure, the broken line indicates the operation of the composite plunger, and the solid line indicates the operation of the third plunger 9C. As is clear from the figure, the composite plunger repeats the process of suction to discharge for pre-pressurization → discharge process → suction to discharge for pre-pressurization → discharge process, and the third plunger 9C In synchronization with this, the discharge process → suction process → discharge process → suction process is repeated. In such a process, the operating characteristics of the two pumps are as follows:
As shown in the figure, the composite pump sucks slowly and discharges quickly, and the third pump sucks quickly and discharges slowly. The reason for this is that when the synthesis pump performs the suction process, the supply pressure of liquid from the liquid tank is generally low, so cavitation is likely to occur in the cylinder chamber 1 and the valves. It is particularly likely to occur when suction is applied rapidly; this cavitation creates bubbles and causes irregular operation.

Therefore, it is advisable to perform the suction process of the synthetic pump as slowly as possible. On the other hand, in the third pump, since the discharge process is a substantial liquid feeding process, during one suction-discharge cycle time,
Continuity of liquid feeding can be maintained by allocating a large amount of time to the discharge process and minimizing the suction process. Also, in the suction process, unlike the suction process of the synthetic pump, the liquid from the synthetic pump is forcibly sent, and the pressure on the suction side of the third pump is very close to that pressure. Therefore, cavitation does not occur and suction can be performed very quickly.

Further, the amount S1 of the liquid discharged by the synthetic plunger is equal to the amount S1 of the liquid sucked by the third plunger 9C and the third liquid discharge amount S1 at the same time as the time required for the discharge process of the synthetic plunger 9C.
It is equal to the sum of the discharge amounts S3 of the plungers 9C, and as a result, a certain amount of liquid is continuously sent to the outside from the third pump chamber 10C. Furthermore, the rotation angle of the cam changes depending on the flow rate, but if the rotation angle of the cam is made smaller, the fourth
In the figure, the output and suction volumes are correspondingly lower,
The larger the rotation angle of the cam, the higher the discharge amount and suction amount. However, the time required for this ejection and suction does not change.

In addition, this preliminary compression pressurization of the synthesis plunger is performed when the third pump chamber, which sucked the liquid discharged from the synthesis pump chamber in the previous process, switches to the process of discharging the liquid to the outside. This is done to make the pressure the same as the external pressure, and during the preliminary compression pressurization, the liquid in the synthesis pump chamber is compressed and pressurized and is not sent to the third pump chamber.

This pre-compression pressurization is performed by detecting the pressure of the liquid discharged from the third pump chamber 10C with a pressure gauge 13 provided in the discharge passage OC of the third pump chamber 10C, and by controlling the control device 7 to detect the pressure from the pressure gauge. The slope of the pressure waveform (that is, the rate of change in pressure on the discharge side of the third pump) is determined based on the information, and the motors are controlled by sending commands based on the slope. That is, according to experiments, the pressure waveform of the liquid discharged from the third pump chamber changes when the liquid sucked by the third plunger 9C is not pressurized to the external pressure (predetermined discharge pressure). If the actual liquid flow IUr of the third pump chamber is smaller than the designed liquid flow rate UO of the third pump), the liquid will be tilted to the right as shown in Figure 5 (a), and the liquid will be pressurized higher than the external pressure. (i.e., Ur > Uo), it will tilt to the left as shown in Figure 5 (l). In this case, the degree of these tilts is equal to the difference in external pressure. Also, the pressure of the prosthesis is equal to the difference in external pressure. (i.e., tJr = tJO), then Fig. 5 (
As shown in b), the slope is zero, that is, parallel to the time axis.

Therefore, if the slope of the pressure waveform is rightward as shown in FIG. Control is performed to appropriately increase the moving distance of the composite plunger and to supply a signal to increase the preliminary compression pressurization. Further, as shown in FIG. 5, if the plunger is tilted to the left, the moving distance of the composite plunger is appropriately reduced to the extent that the tilt becomes zero, and control is performed to supply a signal to reduce the precompression pressurization. Let's do it. In addition, a constant pressure release valve that sends a little more liquid than the required amount of liquid from the synthetic pump to the third pump in advance and releases the excess amount is connected to the discharge path OA or OB of the first or second pump chamber. The release valve may be provided between the third pump chamber 10G and the suction passage IC, and the operating pressure of this release valve may be controlled by the control device 7 to equalize the pressures in the third pump chamber and outside.

[Effects of the Invention] The present invention causes the first plunger and the second plunger to linearly reciprocate within the first and second pump chambers, respectively, by the movement of the first cam and the second cam that operate synchronously by a common cam drive mechanism. Then, according to a predetermined mixture ratio change from the outside, the first
．． Suction of liquid into the second pump chamber and the first pump. The liquid is discharged from the second pump chamber to the third pump chamber, and the third plunger is linearly reciprocated within the third pump chamber by the movement of the cam operated by the independent cam drive mechanism, and the third plunger is moved into the third pump chamber. The first pump chamber and the second pump chamber are configured to suck in the discharged liquid and discharge the liquid to the outside, and the third pump discharges the liquid from inside the third pump to the outside by movement of the third plunger. Since the pressure inside the pump chamber is made to be the same as the external pressure when switching to the process of discharging liquid to the outside, the third pump chamber operates for discharging when switching to the process of discharging liquid to the outside. The liquid flows from the room to the outside simultaneously with the movement of the third plunger without delay, and the amount of outflow per unit time from the flow path to the outside does not drop. Therefore, the two liquids are mixed according to a predetermined mixing ratio change so that the mixing ripple is minimized.

Further, since the first pump and the second pump are synchronized to suction and discharge the solvent, the reproducibility of the operation is high. Therefore, when the two liquids are mixed based on a continuously changing mixing ratio as in gradient elution, a predetermined change in the mixing ratio can be maintained, improving quantitative performance and reproducibility.

Furthermore, the present invention improves constant flow performance by causing the first pump and the second pump to send suitably pressurized liquid to the third pump, and by making the third pump send the liquid to the outside. In this apparatus, since the operation of the first pump, the second cylinder, and the cylinder according to a change in the predetermined mixing ratio is controlled by a common cam drive mechanism, pressure operation control is simplified.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the liquid pump device of the present invention, and FIGS. 2, 3, and 4 are diagrams used to assist in explaining the operation of the pump device. 1A, 1B, 1C: 1st. Second. Third cam 2A, 28.
3: 1st. Second. 3rd gear 4A.

Claims (1)

[Claims] The movement of the first cam and the second cam, which operate synchronously by a common cam drive mechanism, causes the first plunger and the second plunger to linearly reciprocate within the first and second pump chambers, respectively, thereby causing a predetermined mixture ratio change from the outside. Therefore, the liquid is sucked into the first and second pump chambers from the outside and the liquid is discharged from the first and second pump chambers to the third pump chamber by the movement of the cam operated by the independent cam drive mechanism. The third plunger is linearly reciprocated within the third pump chamber to draw into the third pump chamber the liquid discharged by the first pump chamber and the second pump chamber, and to discharge the liquid to the outside. and a liquid feeding pump device configured such that the pressure inside the third pump chamber becomes the same as the pressure outside when switching to the step of discharging the liquid from the third pump chamber to the outside by the movement of the third plunger.