JPH049486Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention is a fluid switching valve used in a sample analyzer, etc. The present invention relates to a fluid switching valve that improves the precision of quantitative determination when used for quantitative determination of minute quantities.

[Conventional technology]

FIG. 4 shows an example of a conventional fluid switching valve (hereinafter referred to as a valve) 1. As shown in FIG. 2 is a diaphragm made of a rubber membrane in the shape of a coin with a round hole. The piston 3 and the piston 4 are connected with a screw and move as one body in the vertical direction in FIG. 4. FIG. 5 shows an enlarged view of the joint between the piston 3 and the piston 4. 5 is a screw. A round hole in the diaphragm 2 fits into the joint between the piston 3 and the piston 4. cylinder 6, 7, 8
They are also held together with screws. Details of this joint portion are shown in FIG. As shown in FIG. 6, O-rings 10 and 11 are provided at each joint of the connecting portion to maintain airtightness between the inside and outside of the valve 1.
The cylinder 8 is provided with cylindrical ports 12 and 13, and the cylinder 7 is provided with a port 14. 15 is a middle cylinder that holds the Y ring 16 and the diaphragm 2. Y-ring 16 and Y-ring 17 prevent air from leaking from working fluid passage (duct) 18. 20 is a spring, and the piston 4
is pushing up.

FIG. 4 shows the initial state of this valve 1. An O-ring 21 provided on the upper side of the piston 3 is pressed against the cylinder 8 by the elastic force of a spring 20. At this time, the flow path between port 13 and port 12 is cut off,
It communicates with port 14. Working fluid passage 18
When high pressure air is sent from the pistons 3 and 4, the pistons 3 and 4 are pushed down against the force of the spring 20. At this time, the O-ring 21 is separated from the cylinder 8 and pressed against the cylinder 7. Therefore, port 1
3 communicates with the port 12 and is blocked from the port 14, thereby switching the flow path.

The conventional valve 1 shown in FIG. 4 is constructed and operates as described above.

FIG. 9 shows another example of a conventional valve 22 called a spool valve (hereinafter referred to as a spool valve). The part that drives the piston 23 up and down has the same structure as the part on which the high pressure air from the working fluid passage 18 of FIG. 4 acts, and is not shown. The driving part of the spool valve 22 needs to be larger and more powerful than that of the valve 1. This is because in the spool valve 22, it is necessary to move the piston 23 against the large frictional resistance caused by the O-ring.

A piston 23 is inserted into the center of a cylinder 24 in the spool valve 22 so as to be slidable up and down. The cylinder 24 is provided with ports 25, 26, and 27. Three grooves are provided on the circumferential surface of the cylindrical piston 23, and O-rings 28, 30, and 31 are fitted into each groove, respectively.

FIG. 9 shows a state in which the piston 23 is driven upward in the figure, and the port 27 is in communication with the port 25 and is blocked from the port 26.

When the piston 23 is driven downward in the figure, the port 27 communicates with the port 26 and is cut off from the port 25.

[Problem that the invention attempts to solve]

The piping diagram in FIG. 7 shows an example of measuring and dispensing a small amount of liquid using the conventional valve 1 shown in FIG. 4.

In FIG. 7, 1 is the conventional valve shown in FIG. 4, and 12, 13, and 14 represent each port. 32 is a syringe for measuring a small amount, and its piston 33 is moved in the vertical direction in the figure. 34 is a dispensed liquid, and a certain amount of liquid is dispensed from a nozzle 36 via a pipe 35 into another container (not shown).

FIG. 8 is a diagram illustrating changes in the volume inside the valve 1 due to the operations of the piston 3 and the diaphragm 2, and the dotted line indicates the position when the piston 3 moves upward in FIG. A in Figure 8
2 shows a state in which the diaphragm 2 has moved upward, and at this time the ports 13 and 14 are in communication. B in FIG. 8 shows the state in which the diaphragm 2 has moved downward, and in this case, the port 1
3 and port 12 are in communication.

Assume now that the previous dispensing has been completed and the diaphragm 2 is in state A. At this time, the nozzle 36,
The interior of the pipe 35, syringe 32, and valve 1 is filled with liquid. Next, when the valve 1 is driven and the pistons 3 and 4 are pushed down to bring the diaphragm 2 into the state B, the movement of the piston 3 and the diaphragm 2 causes the volume change area 3 shown by diagonal lines in FIG.
7, 38, 39 occur. Therefore, the pressure inside the valve 1 decreases. The volume change portion 37 is caused by the diaphragm 2, 38 is caused by the shoulder of the piston 8, and 39 is caused by the head of the piston 3.

The shortage of liquid inside the valve 1 due to the above volume change is replenished mainly from within the nozzle 36, but also from the piping 35. Therefore, the liquid that should originally be filled in the nozzle 36 and the piping 35 becomes insufficient.

In this manner, with the piston 3 being pushed down, the piston 33 of the syringe 32 is pushed down a certain distance, and a certain amount of the dispensing liquid 34 is aspirated.

Next, when the piston 3 is pushed up and the diaphragm 2 is returned to the state shown in FIG. 8A, volume changes 37, 38, 39 occur in the opposite direction. In this case, the pressure inside the valve 1 increases. Therefore, liquid is pushed out from the valve 1 to the nozzle 36 and the pipe 35. In this way, due to the switching operation of the valve 1, the liquid sucked into the valve 1 from the nozzle 36 and the piping 35 is transferred to the nozzle 36 and the piping 3 again.
Pushed to 5. However, since the speed at which the piston 3 rises and falls is different, and the moving direction of the liquid at that time is different, the amount of liquid sucked in and the amount of liquid pushed out are generally different, so the nozzle 36 And the inside of the pipe 35 does not return to its original full state.

As described above, since the amount of liquid in the nozzle 36 fluctuates, there is a problem that even if the piston 33 of the syringe 32 is pushed up a certain distance, the amount of liquid determined by the syringe 32 is not dispensed from the tip of the nozzle 36. It was hot.

Furthermore, in the spool valve 22 shown in FIG.
Since the diameter of the piston 23 is constant and the deformation of the O-ring can be ignored, the volume inside the valve does not change due to the driving of the piston 23. However, piston 23
When the O-ring slides, the O-ring always passes over the hole in the port, which tends to damage the O-ring. Therefore, there was a problem that the durability of the valve was low in terms of maintaining airtightness. Another problem is that since airtightness is maintained by three O-rings, a large driving force is required.

The present invention was developed in view of the above points, and the purpose is to provide a fluid switching valve that can suppress the volume change inside the valve due to opening and closing of the valve, and can quantify and dispense minute amounts of samples with high precision. It is something to do.

[Means for solving problems]

The fluid switching valve of the present invention will be described with reference to FIGS. 1 to 3, and will be described with reference to FIGS.
an upper cylinder 41 with a fluid passage 68 communicating these ports, and two large-diameter piston receiving recesses 54, 55 with working fluid passages 63, 64 communicating with the upper portions of these piston receiving recesses. A cylinder main body is formed by a lower cylinder 42 provided therein, and middle cylinders 43 and 44 provided with a piston sliding space having a smaller diameter than the piston receiving recess and which are airtightly fitted between the upper cylinder and the lower cylinder, Inside this cylinder body are two pistons 52 and 53, each of which has a small-diameter cylindrical or cylindrical shape at the top and a large-diameter cylindrical or cylindrical shape at the bottom. valve bodies 45 and 46 are provided at the upper ends of these pistons,
In addition, a diaphragm 51 is provided closely above these valve bodies, and both ends of these diaphragms are airtightly fixed between the upper cylinder and the middle cylinder, and the portion where these valve bodies abut through the diaphragm is fixed. Valve seats 70 and 71 are formed in two of the ports, and a spring is provided between the large diameter piston bottom surface and the piston receiving recess bottom surface so as to press the valve body against the valve seat through the diaphragm. 5
6 and 57, and a working fluid control valve 72 is connected to alternately supply working fluid to each side of the two working fluid passages.

[Effect]

When a working fluid, such as high-pressure air, is being sent to the working fluid passage (duct) 63 side, the piston 52 is pushed down against the elastic force of the spring 56. Therefore, since the valve body 45 leaves the valve seat 70, the port 65 and the fluid passage 68 communicate with each other. On the other hand, since high pressure air is not sent to the duct 64, the piston 53 is not driven and the valve body 46
remains pressed against the valve seat 71. Port 67 and fluid passage 68 are always in communication. As a result of the above, port 67 communicates with port 65 and is cut off from port 66.

Next, when high pressure air is sent to the duct 64 side,
The piston 53 is pushed down against the elastic force of the spring 57, and the valve body 46 leaves the valve seat 71. At the same time, the high pressure air in the duct 63 is released to the atmosphere, and the spring 56 causes the valve body 45 to move toward the valve seat 7.
It is pressed to 0. Therefore, the port 67 communicates with the port 66 and is cut off from the port 65.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, unless otherwise specifically stated, the materials, shapes, relative positions, etc. of the components described in this example are not intended to limit the scope of the present invention, but are merely illustrative. Just an example.

1 to 3, 40 is a fluid switching valve (hereinafter referred to as a valve) of the present invention, 41 is an upper cylinder, 42 is a lower cylinder, and 43 and 44 are middle cylinders.

The cylinders 41, 42, 43, and 44 are combined with valve bodies 45, 46, and O-rings 47, 48 at their joints to maintain airtightness between the inside and outside of the valve 40. These cylinders are assembled using three bolts through assembly holes 50 shown in FIG.

The valve bodies 45 and 46 have a shape in which a diaphragm 51 is attached to the head of a poppet. Valve body 45,
46 is adapted to fit into the heads of the pistons 52 and 53.

The pistons 52 and 53 are respectively connected to the lower cylinder 4.
Large diameter piston receiving recesses 54, 55 provided in 2
It can be slid freely up and down. The piston receiving recesses 54 and 55 are large diameter cylindrical recesses.

The springs 56, 57 are connected to the pistons 52, 53
It is set below the pistons 52 and 53. Also, the piston receiving recess 54,
Working fluid passages (hereinafter referred to as ducts) 63 and 64 communicating with the upper part of 55 are provided.

Y rings 58, 60, 61, 62 are connected to the duct 6
This is to seal the working fluid, such as high-pressure air, introduced into the valve from 3 and 64, from leaking.

Inside the upper cylinder 41 are ports 65, 66,
67 and a fluid passageway 68 are provided. Inside the upper cylinder 41, valve seats 70 and 71 consisting of annular projections are also provided at positions where the heads of the valve bodies 45 and 46 come into contact. 72 is the duct 63,
64 is a working fluid control valve for alternately supplying working fluid to one side at a time.

Next, the operation of the valve 40 of this embodiment will be described.

The valve 40 is driven to send high pressure air to either one of the ducts 63 and 64. first,
When high pressure air is being sent to the duct 63 side, the piston 52 is pushed down against the elastic force of the spring 56. Therefore, since the valve body 45 leaves the valve seat 70, the port 65 and the fluid passage 68
communicate with. On the other hand, since high pressure air is not sent to the duct 64, the piston 53 is not driven and the valve body 46 remains pressed against the valve seat 71. Port 67 and fluid passage 68 are always in communication. As a result of the above, port 67 communicates with port 65 and is cut off from port 66.

Next, when high pressure air is sent to the duct 64 side,
The piston 53 is pushed down against the elastic force of the spring 57, and the valve body 46 leaves the valve seat 71. At the same time, the high pressure air in the duct 63 is released to the atmosphere, and the spring 56 causes the valve body 45 to move toward the valve seat 7.
It is pressed to 0. Therefore, the port 67 communicates with the port 66 and is cut off from the port 65.

In this way, in order to alternately send high-pressure air to each side of the ducts 63 and 64, a working fluid control valve 72 that can alternately output different pressure states from two output ports, such as a 4-port pilot valve, is used. use. That is, the two outputs of the four-port pilot valve are connected to ducts 63 and 64, respectively.

FIG. 3 is a diagram for explaining the state of the valve body, and the dotted line indicates the state when the piston 53 is raised upward. The vertical movement of the valve body causes a volume change in the shaded area C. Although FIG. 3 shows the movement of the valve body 46, the valve body 45 is designed so that the same amount of change in volume occurs.

Since the pistons 52 and 53 always move in opposite directions, when the volume change occurs in one of the valve bodies 45 and 46 in the direction of increase, a volume phenomenon is occurring in the other valve body. Therefore, the movement of the fluid within the fluid passageway 68 cancels out the volume change due to the movement of the piston. The pressure difference caused by driving the valve is also slightly transmitted to the external piping connected to the valve 40, but since pressure changes in the opposite direction occur simultaneously within the fluid passage 68, the pressure change within the fluid passage 68 is Liquid movement within the fluid passageway 68 occurs first, which is much greater than the pressure change transmitted to the outside of the valve 40. As a result of this liquid movement within the fluid passageway, the pressure differential is immediately resolved. Therefore, liquid movement no longer occurs in the piping outside the valve 40.

In this way, with the valve of the present invention, the volume change that occurs inside the valve when the valve is driven is resolved only within the valve, so it does not affect the liquid volume inside the piping etc. connected to the valve. There is no.

If the valve 40 of the present invention is used in place of the valve 1 shown in FIG. 7, it becomes possible to accurately quantify a small amount of liquid.

Note that the valve 40 of the present invention may be used by rotating it by 90 degrees. It is also possible to use a working fluid such as hydraulic oil instead of high-pressure air.

[Effect of idea]

In the fluid switching valve of the present invention, the volume inside the valve changes by the same amount in the increasing direction and the decreasing direction at the same time due to the driving of the valve, so the effect of the volume change inside the valve due to the driving of the valve does not affect the outside. occurs.

Therefore, when used for quantitative determination and dispensing of minute amounts of liquid, the dispensing and quantitative accuracy is improved.

In addition, unlike spool valves, the O-ring does not pass over the port hole, and it has excellent durability in maintaining airtightness. There is no need to make the driving force as strong as with a spool valve.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an example of the liquid switching valve of the present invention, Fig. 2 is an exploded perspective view of the main components in Fig. 1, Fig. 3 is an enlarged view of the valve body and its surroundings in Fig. 1, and Fig. 4 is a cross-sectional view showing an example of a conventional fluid switching valve, FIG. 5 is an enlarged view of the connecting portion of the two pistons in FIG. 4, FIG. 6 is an enlarged view of the connecting portion of the cylinder in FIG. 4, and FIG. is a piping diagram showing an example of measuring and dispensing a small amount of liquid using the valve shown in Fig. 4, and Fig. 8 is an explanation showing the volume change inside the valve due to the operation of the piston and diaphragm in Fig. 4 9 are sectional views showing other embodiments of the conventional fluid switching valve. 1... Fluid switching valve (valve), 2... Diaphragm, 3, 4... Piston, 5... Screw, 6,
7, 8...Cylinder, 10,11...O ring,
12, 13, 14... Port, 15... Middle cylinder, 16, 17... Y ring, 18... Working fluid passage, 20... Spring, 21... O ring,
22... Valve (spool valve), 23... Piston, 24... Cylinder, 25, 26, 27... Port, 28, 30, 31... O-ring, 32...
Micro-quantity syringe, 33...Piston, 34...
...Dispensing liquid, 35...Piping, 36...Nozzle, 3
7, 38, 39...Volume change portion, 40...Fluid switching valve (valve), 41...Upper cylinder, 42...
...Lower cylinder, 43, 44...Middle cylinder, 4
5, 46... Valve body, 47, 48... O ring, 5
0... Assembly hole, 51... Diaphragm, 52,5
3... Piston, 54, 55... Piston receiving recess, 56, 57... Spring, 58, 60, 6
1, 62... Y ring, 63, 64... Working fluid passage (duct), 65, 66, 67... Port,
68...Fluid passage, 70, 71...Valve seat, 72...
...actuating fluid control valve.

Claims (1)

[Scope of utility model registration request] An upper cylinder having three ports and a fluid passage communicating these ports; a lower cylinder having two large-diameter piston receiving recesses and having a working fluid passage communicating with the upper part of these piston receiving recesses. and a middle cylinder having a piston sliding space with a smaller diameter than the piston receiving recess, which is airtightly fitted between the upper cylinder and the lower cylinder. Two cylindrical or cylindrical pistons with a large diameter lower part are installed so that the upper part slides inside the middle cylinder and the lower part slides inside the lower cylinder. A valve body is provided at the upper end, and a diaphragm is provided closely above these valve bodies, and both ends of these diaphragms are airtightly fixed between the upper cylinder and the middle cylinder, so that these valve bodies hold the diaphragm. A valve seat is formed in two of the ports in the portion that abuts through the valve, and a valve body is pressed onto the valve seat via a diaphragm between the large-diameter piston bottom surface and the piston receiving recess bottom surface. 1. A fluid switching valve characterized in that a spring is disposed as shown in FIG.