JPH0366516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid feeding method in which a predetermined amount of liquid is sucked by a pump and discharged from a discharge part. The present invention relates to a liquid feeding method that can prevent residual droplets after liquid ejection at the distal end of the ejection unit from falling outside of a predetermined dropping process using a simple mechanism, and that can provide excellent quantitative performance and reproducibility.

When a pump is used to drip or inject a certain amount of liquid into a location that requires a certain amount of liquid, the generation of residual droplets at the tip of the discharge portion poses a major problem in terms of quantitative accuracy. That is, after a certain amount of liquid is pumped, residual droplets may be generated at the tip of the discharge portion. The size of these residual droplets varies depending on the flow rate of the liquid being sent, the shape of the tip of the dispensing part, the environment of the dispensing part, etc., but if the residual droplets are removed due to vibrations, shocks, etc. after the specified drop injection process is completed, The remaining droplets may fall from the tip of the dispensing part, reducing the accuracy of the amount of liquid injected, and causing fluctuations in the indicated value in analyzers that perform analysis by injecting minute amounts of sample or reagent dropwise using a pump. If the liquid is injected into a container, problems such as falling outside the container may occur.

One way to deal with such residual droplets generated at the tip of the ejection section is to forcibly remove the residual droplets from the tip of the ejection section. There are two methods that can be considered: sucking the generated residual droplets into the discharge part, and two methods include forcibly applying vibration to the tip of the discharge part after the drip injection process, or using air pressure to blow away the residual droplets. However, in either case, a device is required to force the remaining drops to fall.
The equipment becomes complicated and costs increase significantly.
Therefore, it is preferable to use the above method, but in the case of pumps that use conventional check valves or switching valves, complicated flow and piping are required to suck in the residual droplets generated at the tip of the discharge part. .

That is, FIG. 1 shows a device for sucking residual droplets generated at the tip of the discharge section into the inside of the discharge section when a pump using a conventional check valve is used. One end of a pipe 5 and a pipe 6 are respectively connected via a three-way solenoid valve 4 to a pipe 3 connected to a suction hole 2 in which a check valve 2a is provided, and a check valve 7a is provided inside. One end of a pipe 10 and the other end of the pipe 6 are connected to a pipe 8 connected to the discharge hole 7 via a three-way solenoid valve 9, and the other end of the pipe 5 is connected to the sample liquid 12 in the sample tank 11. The dripping port at the tip of the pipe 10 is inserted into the dripping container 13.
It is placed above. Further, the plunger 14 of the pump 1 is provided with a rack 15 at one end of its side surface.
A pinion 17 attached to the rotating shaft of a pulse motor 16 is meshed with the pulse motor 1.
The rotational motion of the plunger 14 is converted into linear motion by the pinion 17 and the rack 15.
can be moved forward or backward. In addition, 1
8 and 19 are valve switching devices for switching the three-way solenoid valves 4 and 9, respectively; 20 is a pulse motor 16;
and an electric control section that controls the valve switching devices 18 and 19.

When sending liquid in the above device, first, the three-way solenoid valves 4 and 9 are switched to connect the pipes 5 and 3 and the pipes 8 and 6, respectively, and the plunger 14 is moved back to transfer the sample liquid 12 into the pipes 5 and 3. Then, the three-way solenoid valves 4 and 9 are switched to connect the pipes 3 and 6 and the pipes 8 and 10, respectively, and the plunger 14 is advanced to draw the sample inside the pump 1. The liquid is passed through the discharge hole 7 and the pipes 8 and 10, and is injected dropwise into the dripping container 13 from the tip of the pipe 10. Furthermore, if a droplet remains at the tip of the pipe 10 after the droplet injection, this residual droplet is removed. In order to suck the liquid into the pipe 10, the three-way solenoid valves 4 and 9 are switched to connect the pipes 10 and 6, and the pipes 6 and 3, respectively, and the plunger 14 is retreated by a predetermined amount, thereby withdrawing the remaining drops into the pipe 10. It is something that makes you

Therefore, as mentioned above, in the case of a pump using a conventional check valve, complicated piping and flow are required to suck the residual droplets generated at the tip of the discharge part into the inside of the discharge part. There is a need for a liquid delivery method that can reliably retreat and dispose of residual droplets generated at the tip of the ejecting part using a suitable device.

The present invention was developed in view of the above circumstances, and by using a special plunger pump without a check valve as a pump, residual droplets generated at the tip of the discharge part can be easily removed without the need for special piping or flow. It is an object of the present invention to provide a liquid feeding method that can be caused to retreat into the inside of the ejecting part, and therefore can reliably prevent the inconvenience of residual droplets falling from the tip of the ejecting part outside the predetermined drip injection process after liquid ejection. do.

2 and 3 for one embodiment of the present invention.
This will be explained in detail with reference to the figures.

FIG. 2 shows an example of a liquid feeding device used to carry out the liquid feeding method of the present invention. In the figure, reference numeral 21 denotes a pump, and cylinders 22 of the pump 21 are formed in a substantially cylindrical shape with a bottom.
Suction hole 23 and discharge hole 24 separated by 180 degrees
is formed. A lower portion of a plunger 25 formed in a substantially cylindrical shape is inserted into the cylinder 22 in a fluid-tight and slidable manner (moveable in the axial direction and rotatable in the circumferential direction). The plunger 25 has a plurality of notched grooves 26 formed along the axial direction in the lower part of the circumferential wall surface thereof, reaching from a predetermined height to the lower end surface, and a plurality of notched grooves 26 extending along the entire circumference in the substantially middle part in the axial direction. A tooth groove is formed to form a rack 27, and a control section 28 is attached to this rack 27.
A pinion 30 attached to the rotating shaft of a pulse motor 29 for reciprocating the plunger operates in response to a pulse signal sent by the plunger, and the rack 27 and pinion 30 rotate the plunger in forward and reverse directions in response to a signal from the control unit 28. The rotation of the pulse motor 29 is converted into linear reciprocating motion of the plunger 25. Further, a pulse motor 32 for rotating the plunger is connected to the upper side of the plunger 25 through a connecting means such as a spline 31 that is slidable in the axial direction of the plunger. In response to the sent pulses, the plunger 25 is intermittently rotated by 180 degrees around the axis.
In this case, since the rack 27 is formed by tooth grooves being formed over the entire circumference of the plunger 25, even when the plunger 25 is rotated by the motor 32, the rack 27 and the pinion 3 are always connected.
0 means that the meshing state is maintained. Further, 33 is a suction pipe whose one end is inserted into the suction hole 23 and the other end is inserted into the sample liquid 35 in the sample container 34, and 36 is a suction pipe whose one end is inserted into the discharge hole 23.
4, and the other end thereof is a discharge pipe (discharge portion) disposed above the dripping container 37.

Next, a method for sending the sample liquid 35 in the sample container 34 to the dropping container 37 using the above device will be explained. First, the pulse motor 32 for rotating the plunger is activated by a signal from the control section 28, and After arranging the notched groove 26 to face the suction hole 23 as shown in FIG.
7, the plunger 25 is moved backward by converting it into a linear motion, thereby allowing the sample liquid 35 to pass through the suction pipe 33 and the suction hole 23, and the pump 21
into the cylinder 22 of. Next, Figure 3C,
As shown in FIG. 3D, the plunger 25 is rotated 180 degrees by the operation of the plunger rotation pulse motor 32 so that the notch groove 26 and the discharge hole 24 are opposed to each other, and then the motor 29 is rotated as shown in FIG. 3E. is driven to advance the plunger 25, thereby causing the sample liquid 35' in the pump 21 to pass through the discharge hole 24 and the discharge pipe 36, and to be discharged and injected into the dripping container 37 from the end of the discharge pipe 36. .

Furthermore, after the predetermined amount of sample liquid 35' in the pump 21 is discharged and injected into the dripping container 37 by the above operation, the plunger is opened with the notch groove 26 and the discharge part 24 facing each other as shown in FIG. 3F. 25 is moved back by a predetermined amount by the operation of the motor 29, thereby causing the sample liquid remaining at the tip of the discharge pipe 36 to retreat into the discharge pipe 36. In this case, the predetermined amount by which the plunger 25 is retracted is determined as appropriate based on the viscosity of the sample liquid, the inner diameter of the discharge pipe 36, and the like. In addition, when performing the next liquid feeding operation, the plunger 25 is rotated 180 degrees by the operation of the motor 32 with the plunger 25 kept retracted by a predetermined amount as shown in FIG. After the notch grooves 26 are opposed to each other and returned to the original state shown in FIG. 3A, the above-described operation may be repeated.

In this case, in the above device, the plunger 2
The cycle of retreat-rotation-advance-predetermined-amount-backward-rotation in step 5 can be programmed in the control unit 28, and thereby the liquid is automatically fed. However, the above-mentioned liquid feeding method According to the above, residual droplets of sample liquid generated at the tip of the discharge pipe 36 recede within the discharge pipe 36, resulting in inconveniences such as the residual droplets falling after the sample liquid is discharged and lowering the quantitative accuracy. It is possible to transfer liquid with extremely high quantitative accuracy.

Further, in the above method, the rotational motion of the motor 29 is transmitted to the plunger 25 as a linear reciprocating motion using the rack 27 and the pinion 30, and the plunger 25 is caused to move up and down. Therefore, it becomes possible to rotate only the plunger 25, and the mechanism is significantly simplified. Furthermore, since two pulse motors are used to drive the plunger 25, the operation of the plunger can be electrically controlled, and the control is extremely easy and accurate, improving liquid feeding accuracy.

In the above device, a spline is used as the connecting means, but the connecting means is not limited to this, and a sliding key or the like may also be used.

Furthermore, in the above method, the discharge hole of the pump is
Although it is formed in one piece, it may be formed in plural pieces and discharged sequentially.Also, although the angle between the suction hole and the discharge hole is formed at 180 degrees, it is not limited to this, and the present invention can also be applied to other configurations. Various changes may be made without departing from the gist.

As described above, the liquid feeding method of the present invention is a liquid feeding method in which a predetermined amount of liquid is sucked by a pump and then discharged from a discharge part. The plunger has a notch groove extending along the axial direction that reaches the lower end surface in a part of the surface, and a round rack having a plurality of tooth grooves along the circumferential direction in the axially intermediate part. A pulse motor for reciprocating the plunger which is movably inserted and has a pinion attached to the rotary shaft that meshes with the round rack, and a pulse motor for rotating the plunger that rotates the plunger intermittently in conjunction with the reciprocating motion by this motor. Using a plunger pump, the plunger is rotated so that the notched groove faces the suction hole, the plunger is moved back to suck the liquid into the pump, and then the plunger is rotated to make the notched groove face the discharge hole. With the grooves facing each other, move the plunger forward to discharge the liquid to the outside of the pump. After discharging a predetermined amount of liquid, move the plunger back by a predetermined amount with the notched groove facing the discharge hole, and then move the plunger forward to discharge the liquid to the outside of the pump. By receding the remaining liquid inside the discharge part, if a residual drop is generated at the tip of the discharge part, it will fall outside of the prescribed drop injection process, which can be avoided without the need for complicated and expensive equipment. This can be prevented with a simple device without the use of liquids, high quantitative performance and reproducibility can be obtained, and excellent liquid delivery accuracy and a significantly simplified structure have been achieved.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional schematic diagram showing a liquid transfer device using a pump using a conventional check valve, and FIG. 2 is a partial cross-sectional view showing an example of a liquid transfer device used in carrying out the liquid transfer method of the present invention. The schematic diagrams and FIGS. 3A to 3G are operational diagrams showing the operating states of the plunger of the same device, respectively. 21...Pump, 22...Cylinder, 23...
Suction hole, 24...Discharge hole, 25...Plunger,
26...Notch groove, 36...Discharge pipe (discharge part).

Claims (1)

[Claims] 1 In a liquid delivery method in which a predetermined amount of liquid is sucked by a pump and discharged from a discharge part, the pump is a cylinder in which a suction hole and a discharge hole are respectively formed in the side wall, and a notch that reaches the lower end surface on a part of the surface. A plunger in which a groove is formed along the axial direction and a round rack having a plurality of tooth grooves along the circumferential direction is formed in the axially intermediate portion is inserted fluid-tightly and slidably, and is attached to the rotating shaft. The plunger is moved by using a plunger pump having a pulse motor for reciprocating the plunger equipped with a pinion that meshes with the round rack, and a pulse motor for rotating the plunger that rotates the plunger intermittently in conjunction with the reciprocating motion by this motor. Rotate the notched groove to face the suction hole, move the plunger backward to suck the liquid into the pump, then rotate the plunger to face the notched groove to the discharge hole, and move the plunger forward. Discharge the liquid out of the pump,
After discharging a predetermined amount of liquid, the plunger is moved back a predetermined amount with the notch facing the discharge hole,
A liquid feeding method characterized by causing liquid remaining at the end of the discharge part to retreat into the interior of the discharge part.