JPH0643696Y2 - Fluid metering device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention is characterized by linearly moving a piston back and forth.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid quantification device that quantifies a liquid, and more particularly, to a fluid quantification device that can guarantee quantification accuracy even if a motor stop position is slightly displaced.

[Conventional technology]

The sample analyzer has a built-in fluid quantification device for performing processing such as sampling and dilution of the sample. A typical example thereof is a fluid metering device including a cylinder and a piston that reciprocates linearly while being sealed in the cylinder. For example, the following are known.

(A) A motor in which a motor is used as a drive source, and the motion converting means converts the rotational motion of the motor into a reciprocating linear motion of the piston.

(B) An air cylinder that reciprocates linearly is used as a drive source and is connected to a piston.

[Problems to be solved by the device]

Since the quantification accuracy of the fluid quantitation device is directly reflected on the analysis accuracy of the sample analyzer, a quantification device with good reproducibility is required. On the other hand, there is a demand for an inexpensive quantitative measuring device including a control means.

In the case of the above-mentioned (a) quantification device, in order to improve quantification accuracy, a motor such as a stepping motor that can be controlled with high accuracy must be used, and a dedicated control circuit is also required, which is expensive. is there. In the case of the device of (b), the structure of the metering device itself is simple and can be realized at low cost, but an air pressure source such as a compressor and a switching valve are additionally required, and the cost as a whole becomes expensive. There is also a problem that it is difficult to stabilize or control the suction speed or the discharge speed of the metering device.
Further, when the sample is sucked in a fixed amount, it may be necessary to suck the sample at a constant speed.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a fluid quantification device having good quantification accuracy while being inexpensive, including control means.

[Means for Solving the Problems]

In order to achieve the above object, the fluid metering device of the present invention, as shown in FIG. 1 to FIG. 3, has a piston which is sealed by packing and reciprocates in a cylinder by a moving means connected to the piston. In a fluid metering device that is moved and sucks fluid from an inflow port provided in a part of a cylinder to quantify the fluid, a vertical direction continuous with a fixing member 54 that fixes the cylinder 55. The motor 10 attached to the fixing member 11, the eccentric shaft 16 eccentrically attached to the rotating shaft 12 of the motor, the bearing 18 rotatably attached to the eccentric shaft, and the vertical fixing member. Fixing members 40 and 29 in a substantially horizontal direction that are connected to the substantially central portion and the lower end portion of 11 and a guide shaft supported by the fixing members 40 and 29 so as to be perpendicular to the rotation shaft 12 of the motor 10.
30, an upper moving member 20 and a lower moving member 22 that move integrally along the guide shaft 30 while sandwiching the bearing 18 with a gap, and two that detect the rotational position of the motor 10. The detection means 62, 64 and the piston 51 provided above the moving member 20 so as to move together with the moving members 20, 22.
And the moving members 20, 22 are provided at the portions in contact with the bearing 18 so as to have a shape that matches a part of the locus B ₂ drawn by the outer edge of the bearing 18 when the rotating shaft 12 of the motor 10 makes one revolution. It is characterized in that it includes the hollows 20a and 22a, and even if the rotation stop position of the motor 10, which is the moving means, slightly varies, the quantitative amount does not vary.

[Action]

As the rotating shaft 12 of the motor 10 rotates, the eccentric shaft 16 rotates eccentrically. Therefore, the bearing 18 also eccentrically rotates around the rotary shaft 12 of the motor. Since the moving members 20, 22 sandwich the bearing 18 therebetween, one or the other of the moving members 20, 22 is pushed by the bearing due to the eccentric movement of the bearing 18, and the moving members 20, 22 are guided along the guide shaft 30. Are moved up or down. Since the piston 51 is provided above the upper moving member 20, one rotation of the motor 10 causes the piston 51 to make one reciprocating linear movement in the cylinder 55 to quantify the fluid.

By the way, in the portions of the moving members 20 and 22 that come into contact with the bearing 18, respectively, when the rotating shaft 12 of the motor makes one revolution, recesses 20a and 22a having the same shape as a part of the locus B ₂ drawn by the outer edge of the bearing 18 are formed. Is provided. Therefore, while the bearing 18 is in contact with the upper moving member 20 in the recess 20a and in contact with the lower moving member 22 in the recess 22a, even if the bearing 18 moves (the motor rotates Also, the moving members 20, 22 and the piston 51 do not move up and down and remain stopped. Therefore, even if the stop position of the bearing 18 varies slightly, the amount of suction or discharge of the fluid does not vary.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, the shape of the components described in this embodiment, the relative arrangement, etc., are not intended to limit the scope of the present invention to only those unless otherwise specified, and are merely examples of explanation. Only.

FIG. 1 is a right side sectional view of an embodiment of the fluid metering device of the present invention, and FIG. 2 is a front view of the same. (However, some parts in front of the bearing are omitted for clarity).
Reference numeral 11 is a plate-like fixing member which is set up substantially vertically. The motor 10 is attached to the fixing member 11 so that the rotating shaft 12 is substantially horizontal. An eccentric member 14 is attached to the rotating shaft 12. The eccentric member 14 is provided with an eccentric shaft 16, and the eccentric shaft 16 is eccentric to the shaft 12. The eccentric shaft 16 and the shaft 12 are parallel to each other. A bearing 18 having a relatively large diameter is attached to the eccentric shaft 16. Therefore, when the shaft 12 of the motor rotates, the bearing 18
Eccentrically rotates around. Two moving members 20, 22 are arranged so as to sandwich the bearing 18 therebetween, and these moving members 20, 22 are connected by a connecting member 24. The gap between the moving members 20 and 22 is set to be slightly wider than the outer diameter of the bearing 18. A hole is provided in the connecting member 24, and sliding bearings 26 and 28 are fitted in the holes. Lateral fixing members 29 and 40 are attached to the fixing member 11, and the guide shaft 30 is supported between the fixing members 29 and 40 so as to be perpendicular to the rotating shaft 12 and the eccentric shaft 16. This guide shaft 30 is a sliding bearing 26,
It is installed inside 28. Further, springs 33 and 31 are arranged around the guide shaft 30 between the fixed member 40 and the upper moving member 20 and between the lower moving member 22 and the fixed member 29, respectively.

FIG. 2 is a front view of the fluid metering device of the present invention. The upper moving member 20 is pushed up by the bearing 18,
The moving members 20, 22 are in the uppermost position. The spring 33 is contracted and pushes the moving members 20 and 22 downward. Now, if the shaft 12 of the motor rotates, the bearing 18 also rotates about the shaft 12. Then the bearing 18
The moving members 20, 22 come to the lowermost position when they come into contact with and push down the lower moving member 22 and rotate 180 degrees. At this time, the spring 31 is contracted and pushes the moving members 20 and 22 upward.

If the shaft 12 of the motor further rotates in the same direction, the bearing 18 again abuts against the upper moving member 20 and pushes it up, and rotates 360 degrees to return to the original state. In this way, each time the shaft 12 of the motor 10 makes a half rotation, the moving members 20, 22 repeat the uppermost position and the lowermost position. Therefore, the upper moving member
If the piston 51 is attached to 20, the piston 51 can be reciprocated once inside the cylinder 55 by one rotation of the motor 10.

As shown in FIG. 1, member 44 is attached to upper moving member 20 by set screw 42. The member 46, to which the piston 51 is attached and the projecting edge 47 is provided at the lower portion, is held with a gap between the member 44 and the stopper 48 having a hole at the center. 49 is a stopper for locking. Element
A male screw is formed on the outer side of 44 and a female screw is formed on the inner side of the stopper 48, and the amount of the above-mentioned gap is changed by the degree of tightening of the stopper 48 to the member 44, and the movement of the piston 51 is changed. The distance, that is, the amount of suction or discharge of fluid can be adjusted. A cylinder 55 is attached to the fixing member 54 attached to the upper end of the fixing member 11. A packing 50 for sealing the piston 51 is held by a holder 52 at the lower part of the cylinder 55.
The upper and lower parts of the cylinder 55 are provided with inflow / outflow ports 56, 58 for inflowing or outflowing the liquid.

In addition, the lower moving member 22 is in contact with the fixed member 11,
Rollers 34, 38 are rotatably mounted by shafts 32, 36. Therefore, the moving members 20 and 22 can move only up and down along the guide shaft 30 without rotating about the guide shaft 30.

The moving members 20 and 22 sandwich the bearing 18 therebetween, but the portions of the moving members 20 and 22 that contact the bearing 18, that is,
Recesses 20a, 22a are formed in the lower and upper portions of the moving members 20, 22, respectively.
Are provided respectively.

FIG. 3 is a schematic diagram for explaining the movement of the bearing and the moving member. A ₁ indicates the center of the rotary shaft 12 of the motor,
A ₂ and A ₃ respectively indicate the positions of the centers of the eccentric shafts 16 when the bearings are located at the top and bottom. B ₁ is the locus of the eccentric shaft 16 when the rotary shaft 12 of the motor makes one revolution (shown by a thin two-dot chain line). This is a circle centered on A ₁ .
B ₂ is a locus drawn by the outer edge of the bearing 18 when the rotating shaft 12 of the motor makes one revolution (indicated by a thin two-dot chain). This is also a circle centered on A ₁ . When the radius of the bearing 18 is R, the distance between the center of the rotating shaft 12 of the motor and the center of the eccentric shaft 16 of the bearing, that is, the radius of the locus B ₁ is r.
And Then, the radius trajectory B ₂ is centered on the A ₁ (R +
r), that is, a curve having a curvature of 1 / (R + r). It is assumed that a depression 20a having a curvature 1 / (R + r) and a depth d is provided in the lower portion of the upper moving member 20. Then, as shown in FIG. 3, around the axis B _3, respectively the angle theta [theta = co
s ^-1 (R + rd) / (R + r)]
Since 8 contacts the upper moving member 20 within the recess 20a, even if the bearing 18 moves, the upper moving member 20 does not move up or down. This is because the shape of the depression 20a and the locus of the outer edge when the bearing 18 moves are the same. That is, if the angle θ is about the axis B ₃ ,
Wherever the bearing 18 is stopped, the upper moving member 20 maintains the uppermost position, and it is not necessary to make the stop position of the bearing 18 strict. Note that w is the width of the depression 20a.

On the other hand, the positions of the bearing 18 and the moving members 20 and 22 when the rotating shaft 12 of the motor is half-turned are indicated by thick double-dotted lines. A depression 22a having a curvature 1 / (R + r) is formed in the upper portion of the lower moving member 22 as in the lower portion of the upper moving member 20.
Is provided and the lower moving member 22 maintains the lowermost position wherever the bearing 18 is stopped within the range of the angle θ.

Thus, recesses 20a having the same curvature as the track B _2, by providing the 22a, in the uppermost position and the lowermost position, be varied stopping position of the bearing 18 is slightly its stop position of the moving member 20, 22 A region (angle ± θ) that is not affected is created, and it is not necessary to perform high-precision control using a stepping motor to make the stop position constant. For example, a DC motor with a gear head
All you need to do is a simple control such as ON / OFF.

In addition, in order to stop the motor 10, a detection means for detecting it is necessary. For example, as shown in FIG. 2, a plate-shaped member to be detected 60 may be attached to the upper moving member 20, and this may be detected by detecting means 62, 64 such as a photo interrupter. The detection means 62 detects that the moving members 20, 22 and the piston 51 are at the uppermost position, and the detection means 64 detects that they are at the lowermost position. Further, the detected member 60 may be attached to the eccentric member 14 to detect the rotational position of the eccentric member 14, and various other implementations are possible.

Next, a sample dilution system using the fluid quantification device of the present invention will be briefly described. FIG. 4 is an example of the fluid circuit diagram. 100 is a fluid metering device of the present invention. 102 is another relatively large volume fluid metering device. Fluid metering device
A sample suction tube 106 is connected to the upper inlet / outlet 56 of the 100, and the lower inlet / outlet 58 is connected to the fluid metering device via the valve V _1.
It is connected to the upper inlet / outlet 104 of 102, and is further connected to a diluent tank 112 via a valve V ₂ .

First, the valve V ₁ is closed and the fluid quantification device 100 is put into the suction state, so that a fixed amount of the sample in the sample container 108 is sucked into the tube 106 from the tube 106. On the other hand, the valve V ₂ is opened and the fluid metering device 102 is in a suction state, so that a fixed amount of the diluting liquid is sucked from the diluting liquid tank 112.

Next, the tube 106 moves above the container 110. The valve V ₁ is opened, the valve V ₂ is closed, and the fluid metering device 10
When 0 and 102 are in a discharge state, a fixed amount of the sample and a fixed amount of the diluent are discharged into the container 110, and a fixed amount of the diluted sample is prepared.

[Effect of device]

In the fluid metering device of the present invention, the bearing is eccentrically attached to the motor shaft, and the moving member that sandwiches the bearing has a recess that corresponds to a part of the trajectory drawn by the outer edge of the bearing when the motor shaft makes one rotation. Since it is provided, the recess can create a region in which the positions of the moving member and the piston do not change even if the bearing stop position slightly changes. Therefore, it is not necessary to control the motor with high precision, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a right side sectional view showing an embodiment of the fluid metering device of the present invention, FIG. 2 is a front view of the same (however, a part of the front part of the bearing is omitted), and FIG. FIG. 4 is a schematic diagram for explaining the movement of the members, and FIG. 4 is a system diagram showing an example of a fluid circuit diagram using the fluid metering device of the present invention. 10 ... Motor, 11 ... Fixed member, 12 ... Rotating shaft, 14 ... Eccentric member, 16 ... Eccentric shaft, 18 ... Bearing, 20 ... Upper moving member,
22 ... Lower moving member, 20a, 22a ... Recess, 24 ... Connecting member, 2
6, 28 ... Slip bearings, 29 ... Fixing members, 30 ... Guide shafts, 3
1, 33 ... Spring, 32, 36 ... Shaft, 34, 38 ... Roller, 40
... Fixing member, 42 ... Set screw, 44,46 ... Member, 47 ... Flange,
48, 49 ... Stopper, 50 ... Packing, 51 ... Piston, 52 ... Retaining tool, 54 ... Fixing member, 55 ... Cylinder, 56, 58 ... Inflow / outflow port, 60 ... Detected member, 62, 64 ... Detecting means, 100 , 102 ... fluid quantification device 104 ... inflow outlet, 106 ... tube, 108 ... sample container, 110 ... container, 112 ... dilution tank, the center of the rotating shaft of the a ₁ ... motor, a ₂ ... bearing is uppermost located The position of the center of the eccentric shaft, A ₃ ... the position of the center of the eccentric shaft when the bearing is at the lowest position, B ₁ ... the locus of the eccentric shaft when the rotating shaft of the motor makes one rotation, B ₂ ... the motor , The trajectory drawn by the outer edge of the bearing when the rotation axis of the bearing makes one revolution, B ₃ ... Axis, R ... Radius of bearing, r ... Radius of trajectory B ₁ , d ... Depth of depression,
θ… angle, V ₁ , V ₂ … valve

Claims (1)

[Scope of utility model registration request] 1. A piston is sealed by a packing,
In the fluid quantification device for quantifying the fluid, the fluid is sucked from an inflow port provided in a part of the cylinder by being reciprocally linearly moved in the cylinder by a moving unit connected to the piston, and the cylinder ( The motor (10) attached to the vertical fixing member (11) that is connected to the fixing member (54) that fixes the motor (55), and the eccentricity that is eccentrically attached to the rotation shaft (12) of the motor. Axis (16)
And a bearing (18) rotatably attached to the eccentric shaft, and a substantially horizontal fixing member (40, 29) connected to the substantially central portion and the lower end of the vertical fixing member (11). And the guide shaft (30) supported by the fixing members (40, 29) so as to be perpendicular to the rotation shaft (12) of the motor (10) and the bearing (18) with a gap therebetween. While the upper moving member (20) and the lower moving member (22) move integrally along the guide shaft (30), and two detecting means (62, 64) for detecting the rotational position of the motor (10). And moving members (20, 22)
The rotating shaft (12) of the motor (10) is respectively in contact with the piston (51) provided above the moving member (20) so as to move with the bearing (18) of the moving member (20, 22). Quantification of a fluid characterized by including recesses (20a, 22a) provided so as to have a shape that coincides with a part of a trajectory (B ₂ ) drawn by the outer edge of the bearing (18) when the bearing makes one revolution. apparatus.