JP2699451B2 - Plunger pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plunger pump which feeds liquid by reciprocating a plunger, and more particularly to a single plunger pump having one plunger.

The plunger pump is used, for example, in a liquid chromatograph, a flow injection analyzer, or the like when a liquid is sent at a high pressure, a constant flow rate, and a small pulse flow.

(Prior Art) A plunger pump repeats suction and discharge by reciprocating movement of a plunger, but a single plunger pump cannot supply liquid during suction. Therefore, a large-capacity damper is provided in the discharge flow path, and suction is performed at high speed.
The pulsation is reduced by performing the discharge at a constant speed.

(Problems to be Solved by the Invention) In the conventional single plunger pump, not only a large-capacity damper is required, but also air bubbles are easily generated because suction is performed in a short time.

In the gradient elution method in which the composition of the mobile phase is changed with time by liquid chromatography, there is a low-pressure gradient method in which the solenoid valves of a plurality of mobile phases are switched in one cycle of inhalation to set the composition of the mobile phase to a set composition. But,
In the low pressure gradient system, a single plunger pump that performs high-speed suction cannot be used.

To eliminate the above disadvantages of single plunger pump,
A double plunger system in which two pump heads are connected in series or in parallel may be used. However, since the structure is such that two plungers are driven, it is inevitable that the pump head becomes expensive.

Also, when a compressible liquid is sent at a high pressure, the discharge is not performed immediately when the plunger starts discharging,
Drop of liquid supply occurs.

The present invention has the drawbacks of a single plunger pump that suction must be performed at a high speed, that there is a time period during which discharge cannot be performed, and that no liquid is lost even when compressible liquid is supplied. It is intended to solve this.

(Means for Solving the Problems) In the present invention, the chamber in which the plunger reciprocates is separated into a main chamber on the distal end side of the plunger and a sub-chamber on the proximal end side by the seal member, and the inlet and the outlet of the flow path of the main chamber are separated. Each has a check valve, connects the outlet of the flow path of the main chamber to the inlet of the flow path of the sub-chamber, makes the diameter of the plunger thicker on the distal end side and thinner on the proximal end side, and the part where the diameter changes The plunger is driven so as to reciprocate only in the chamber, the plunger pump body sucks in from the inlet of the main chamber flow path, and discharges from the outlet of the sub chamber flow path, and the first time of discharge from the main chamber. A control unit for increasing the plunger speed.

(Operation) The volume of the inside of the main plunger is changed by the movement of the tip of the plunger in the main plunger, and the action of the check valves at the inlet and the outlet of the flow path of the main chamber causes the liquid to be sent to the main chamber. It is. In the sub-chamber, the reciprocating movement of the plunger causes the portion of the plunger whose diameter changes to reciprocate, thereby changing the volume in the sub-chamber.

When the plunger moves in the distal direction, the liquid is supplied from the main chamber, and in the sub-chamber, the portion of the plunger whose diameter changes moves in the distal direction, so that the volume of the sub-chamber also increases. Since the volume is larger than the volume increase of the sub chamber, the liquid is sent from the sub chamber outlet.

When the plunger moves in the proximal direction, the main chamber performs a suction operation, and at this time, the movement of the liquid between the main chamber and the sub chamber is stopped by the outlet side check valve of the main chamber. In the sub-chamber, the volume of the plunger whose diameter is changed moves toward the base end, thereby reducing the volume, and the liquid in the sub-chamber is sent from the sub-chamber outlet.

In this way, the liquid is sent from the outlet of the sub chamber in any direction of the reciprocating movement of the plunger, and there is no time zone during which the liquid cannot be discharged. Since the discharge is performed continuously, there is no need to perform the suction at a high speed.

When the compressible liquid is sent at a high pressure, the ejection is not performed immediately when the main chamber starts to eject, and a drop of the liquid occurs. Therefore, by increasing the plunger speed at the beginning of the discharge from the main chamber so as to discharge extra by an amount corresponding to the missing amount, the loss due to the compressibility of the liquid is corrected.

FIG. 1 shows a plunger pump main body according to an embodiment.

Reference numeral 2 denotes a chamber in which a plunger 4 reciprocates. The chamber 2 includes a main chamber 2a on the distal end side of the plunger 4 and a sub-chamber on the proximal end side by the sealing member
2b.

A check valve 8 is provided at the inlet of the flow path of the main chamber 2a,
A check valve 10 is provided at the outlet of the flow path. The flow path 12 connected to the check valve 10 is connected to the inlet of the sub chamber 2b. The inlet of the main chamber 2a is the suction port of this pump,
The outlet of the sub-chamber 2b is the discharge port of this pump.

In the plunger 4, the diameter of the distal end portion 4a is large, and the diameter of the proximal end portion 4b is smaller than the diameter of the distal end portion 4a. The changing portion 4c of the diameter of the plunger 4 exists in the sub-chamber 2b, and the range of the reciprocating movement of the plunger 4 is
The drive is regulated so as not to go out of 2b. The plunger 4 is separated from the chamber 2 by the sealing member 14 of the sub chamber 2b.
The outside is sealed.

A plunger holding portion 16 is provided at the base end of the plunger 4, and a cam 20 abuts on the base end of the plunger holding portion 16, and the plunger holding portion 16 is pressed toward the cam 20 by a spring 18. 17 is a slide bearing.

The shape of the cam 20 is set and programmed to perform suction and discharge.

Now, the operation when the ratio of the cross-sectional area of the distal end portion 4a to the proximal end portion 4b of the plunger is 2: 1 will be described with reference to FIG.

Since the check valves 8 and 10 are provided at the inlet and the outlet of the flow path of the main chamber 2a, the liquid transfer shown in FIG. Done.

In the sub-chamber 2b, the portion where the diameter of the plunger changes
By the reciprocating movement of 4c, the volume changes as shown in FIG. 2 (B). The change in the volume of the sub chamber 2b is opposite to the change in the volume of the main chamber 2a. That is, the main chamber 2a
When the discharge is performed from the sub chamber 2b to the sub chamber 2b
Then, when the main chamber 2a inhales, the sub chamber 2b performs discharge. The suction and discharge speeds of the sub-chamber 2b are half of the suction and discharge speeds of the main chamber 2a because the ratio of the diameter of the distal end 4a to the proximal end 4b of the plunger 4 is 2: 1. .

The sum of the discharge of the main chamber 2a and the amount of suction and discharge of the sub-chamber 2b, that is, the supply of liquid from the sub-chamber 2b is performed at a constant speed without a pulsating flow as shown in FIG. Liquid.

As in the embodiment of FIG. 1, the cross-sectional area of the base end 4b is
In the case where the cross-sectional area is 1/2, the speed of the plunger in the main chamber 2a at the time of discharge and the speed at the time of suction may be controlled to be constant. However, the ratio of the cross-sectional areas of the distal end 4a and the proximal end 4b of the chamber 4 is not limited to 2: 1. For example, when the cross-sectional area of the base end 4b is smaller than 1/2 of the cross-sectional area of the front end 4a, the main chamber 2a may be configured to perform suction at a low speed and discharge at a high speed. However, since the cross-sectional area of the base end 4b of the plunger 4 affects the strength of the plunger 4, it cannot be reduced too much. Conversely, when the cross-sectional area of the proximal end 4b is larger than 1/2 of the cross-sectional area of the distal end 4a, suction may be performed at a high speed and discharge may be performed at a low speed on the main chamber 2a side.

The liquid feeding operation shown in FIG. 2 is an ideal liquid feeding without considering the compressibility of the liquid to be fed. However, when the compressible liquid is sent at a high pressure, the ejection is not immediately performed when the main chamber 2a starts the ejection, and the liquid is lost. Here, as shown in FIG. 3, the main chamber 2a is so ejected as to have a margin corresponding to the missing amount.
The plunger speed may be increased in the first time of discharge from the plunger. a and b are speeded parts. If such a non-compressible liquid is sent at a partially increased discharge speed, as shown in FIG.
Is performed. However, in the case of sending a compressible liquid, the loss due to the compressibility of the liquid is corrected as shown in FIG. 3 (D).

Although not shown in the figure, a control unit is provided to control the moving speed of the plunger 4.

The embodiment of FIG. 1 uses a cam to drive the plunger 4.
Although a mechanism using 20 is shown, crank driving is generally performed in addition to cam driving to drive the plunger. In crank driving, the speed of the plunger is controlled by controlling the rotation speed of the crankshaft. Crank drive is also included in the present invention.

(Effect of the Invention) In the plunger pump of the present invention, the chamber in which the plunger reciprocates is separated into the main chamber on the distal end side and the sub-chamber on the proximal end side of the plunger by the sealing member, and the plunger is provided at the inlet and the outlet of the flow path of the main chamber. Each provided a check valve, connected the outlet of the flow path of the main chamber to the inlet of the flow path of the sub-chamber, and made the diameter of the plunger thicker at the distal end and thinner at the proximal end,
The plunger is driven so that the diameter change portion reciprocates only in the sub-chamber, suction is performed from the inlet of the main chamber flow path, and discharged from the sub-chamber flow path outlet. Since control is performed so that the plunger speed is increased at the first time of the discharge, a section in which the liquid cannot be sent even though it is a single plunger pump can be eliminated, and the liquid having a small pulsating flow can be sent even with a compressible liquid.

Since the suction speed can be reduced, the plunger pump can also be used in a constant pressure gradient type liquid chromatograph in which two or more liquids are sucked and mixed in one step of suction.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment, and FIG.
FIGS. 3B and 3C are diagrams showing an example of the operation when a non-compressible liquid is sent using the embodiment, and FIGS. 3A to 3D show the operation of the embodiment. It is a figure showing an operation. 2 ... chamber, 2a ... main chamber, 2b ... sub-chamber, 4 ... plunger, 4a ... plunger tip, 4b ...
… The base end of the plunger, 4c… the part where the diameter of the plunger changes, 6 …… the seal member, 8,10 …… the check valve, 12 …… the connection channel, 20… the cam.

Claims (1)

(57) [Claims] A plunger reciprocating chamber is separated by a seal member into a main chamber at the distal end of the plunger and a sub-chamber at a proximal end of the plunger. The outlet of the flow path of the main chamber is connected to the inlet of the flow path of the sub-chamber, and the diameter of the plunger is large at the distal end and narrow at the proximal end, and the portion where the diameter changes reciprocates only in the sub-chamber. The plunger is driven in such a manner that the plunger is sucked in from the inlet of the main chamber flow path and is discharged from the outlet of the sub chamber flow path, and control to increase the plunger speed in the first time of discharge from the main chamber A plunger pump comprising: