JP3343661B2 - Pulsating damper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulsation damper used in liquid chromatography.

[0002]

2. Description of the Related Art Piston pumps are often used as liquid pumps for liquid chromatography. The reasons are that the capacity in the pump is small, discharge can be performed continuously, that the pump is inexpensive, that a constant flow rate can be obtained regardless of the pressure drop throughout the flow path system, and the like.

[0003] However, since the supply of the mobile phase is a pulsating action, in the case of a large-capacity detector, there is a possibility that a periodic noise is generated and interference occurs. In addition, when two liquids are mixed by switching one pump, a situation where the mixing ratio is not constant occurs due to the pulsating action.

[0004] In order to eliminate the above-mentioned problems, a so-called pulsating damper for removing pulsating flow is used in a pump having such a pulsating action. There are various types, which are appropriately selected depending on the type of device, use conditions, and the like. A typical structure is shown in FIG.

In this method, one side portion A of the diaphragm valve 3 is used as a part of a flow path, an inlet 4 and an outlet 5 are provided here, and a compartment 6 filled with oil O is provided on the other side. And a piston 8 that slides inside the cylinder 7 and a coil spring 9 that presses the piston 8. Hereinafter, the principle of the pulsation damper will be described with reference to FIG.

[0006] The mobile phase L entering the portion A via the tube 10 is a pulsating flow, and there are times when the pressure is high and times when it is low. Assuming that the pressure is large (the state shown in the figure), the mobile phase L that has entered the portion A deforms the diaphragm valve 3 by the pressure to increase the volume of the portion A.
Then, the volume of the compartment 6 decreases, and the oil O corresponding to the reduced volume enters the cylinder 7. At this time, since the piston 8 in the cylinder 7 is pressed by the coil spring 9, the piston 8 is in resistance to the inflow of the oil O, so that a certain amount of the mobile phase L flows out from the outlet 5. However, the flow rate of the mobile phase L flowing out of the outlet 5 is naturally smaller than the flow rate flowing in from the inlet 4.

On the other hand, when the state in which the pressure is large ends, the mobile phase L exerts a force to press the diaphragm valve 3 on the coil spring 9.
The force of pressing the piston 8 overcomes this force, the piston 8 moves to the left in the figure, and as a result, attempts to return the deformed diaphragm valve 3 to its original state. Therefore, the mobile phase L in the portion A flows out of the outlet 5. That is, the pressure decreases, and even if there is no flow rate of the mobile phase L flowing from the inlet 4, a certain amount of the mobile phase L flows out.

[0008]

At this time, whether or not the pulsating flow is properly eliminated depends on whether or not the force of the coil spring 9 can be set so as to properly adapt to the pressure of the pulsating flow. is not. That is, when the pressure of the pulsating flow is high, the piston 8 is supposed to be pushed strongly and move deep inside the cylinder 7. However, in practice, there are limits to the deformation of the diaphragm valve, the amount of oil O, the capacity of the cylinder 7, and the like, so that it was not possible to move the piston 8 significantly, and some measure had to be taken.

Therefore, in order to increase the initial pressure for moving the piston 8 by urging the coil spring 9 toward the diaphragm valve 3 in advance at the time of high pressure, the coil spring fixing position opposite to the piston 8 is usually set to A screw mechanism is provided here so as to be slidable with respect to the cylinder 7.

Thus, the piston 8 is maintained at the normal position even when the pressure is high. However, when the type of the column to be installed is changed and the liquid pressure changes, or when a liquid having a different viscosity is used, or When changing the setting of the pump flow rate, it is necessary to adjust the pressure according to changes in the situation, and when the pressure increases over time due to clogging of the column packing material, frequent fine adjustment is required. There is
It is difficult to properly adjust the screw, and there are many problems related to the adjustment, such as forgotten and damage to the diaphragm valve.

[0011]

In view of the above points, the present inventor has finally completed the pulsatile damper of the present invention as a result of intensive studies and is characterized by a piston type damper used for liquid chromatography. A pulsating damper for a liquid sending pump, a part of the liquid sending flow path is formed on one side of a diaphragm valve, and a chamber filled with oil is provided on the other side,
A spring mechanism for urging a piston fitted in the cylinder to the compartment side, the spring mechanism comprising a concentric combination coil spring having different free heights. It is in.

Among the components constituting the pulsating damper of the present invention, the diaphragm valve, the compartment, the cylinder, and the piston may have the same structure as that used in the conventional pulsating damper. The present invention is not limited at all.

The spring mechanism of the present invention is greatly different from the conventional spring mechanism in that an adjusting screw mechanism is not required. Therefore, a plurality of coil springs are used and their free heights are different from each other. . The plurality of coil springs are concentric combination coil springs, but the term “concentric” used here is not strict, and may be slightly off-axis. Also, this concentric combination coil spring has different free heights,
It is more preferable that the outer one is the highest and the inner one is lower. In order to gradually change the spring strength, it is sufficient to provide a large number of springs.

The strengths of the coil springs constituting the concentric combination coil spring may be the same, but the spring strength decreases as the free height decreases in order to provide a spring strength sufficient to cope with a large pressure. It is preferable that the strength be strong.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.

FIG. 1 schematically shows an example of a pulsation damper 1 according to the present invention (hereinafter, referred to as the present invention damper 1). A part A of the diaphragm valve 3 is a part of the flow path, an inlet 4 and an outlet 5 are provided here, and the other side is filled with a compartment 6 filled with oil O, Room 6
There is no difference from the prior art in having a cylinder 7 communicating with the piston and a piston 8 sliding inside the cylinder.

However, as the spring mechanism for pressing the piston 8, the concentric combination coil spring 2 is used, and the present invention does not include a screw mechanism portion whose spring position is adjusted by the pressure of the mobile phase.

As is apparent from FIG. 2, the concentric combination coil spring 2 is formed by concentrically combining three coil springs 21, 22, and 23. The free heights are all different and the outer coil spring 21 is the highest and the inner coil spring 23 Is the lowest. The element wire diameter is smallest on the outside and increases in the following order. The reason why the winding directions of the coils are alternately changed to right-handed winding and left-handed winding is to prevent the coils from meshing with each other.

[0019]

As described above in detail, the pulsating damper according to the present invention is a pulsating damper for a piston type liquid feed pump used for liquid chromatography, and a part of the liquid feed passage is formed by a diaphragm valve. It has a side wall, and has a compartment filled with oil on the other side and a cylinder communicating with the compartment, and urges a piston fitted in the cylinder toward the compartment. The spring mechanism is characterized by being constituted by concentric combination coil springs having different free heights, and even when the pressure of the mobile phase changes due to column replacement or the like, any strength of the coil spring is adjusted. The concentric combination coil spring has the advantages that it can be suitably used as it is without any adjustment, and that the device itself can be made compact because the required space can be made extremely small. That is a very sophisticated invention.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a pulsation damper according to the present invention.

FIG. 2 is a schematic sectional view showing an example of a spring mechanism of the present invention.

FIG. 3 is a schematic sectional view showing the principle of a pulsation damper.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulsation damper 2 Concentric combination coil spring 21 Coil spring 22 Coil spring 23 Coil spring 3 Diaphragm valve 4 Inlet 5 Outlet 6 Compartment 7 Cylinder 8 Piston 9 Coil spring A One side part O Oil L Mobile phase

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 30/32 G01N 30/20 G01N 30/26

Claims (1)

(57) [Claims] 1. A pulsating flow damper for a piston type liquid feed pump used for liquid chromatography, wherein a part of a liquid feed passage is constituted by one side of a diaphragm valve, and the other side is provided with a compartment filled with oil. A cylinder communicating with the compartment, wherein a spring mechanism for urging a piston fitted in the cylinder toward the compartment is constituted by concentric combination coil springs having different free heights. A pulsating damper characterized in that: