WO2000047894A1

WO2000047894A1 - Trace liquid suction and discharge device

Info

Publication number: WO2000047894A1
Application number: PCT/JP2000/000727
Authority: WO
Inventors: Kazutomi Yokota
Original assignee: Kazutomi Yokota
Priority date: 1999-02-15
Filing date: 2000-02-10
Publication date: 2000-08-17

Abstract

A constant volume suction and discharge device which can be used in a dispensing device and an automatic analyzer and is simple in structure, less in number of parts, high in reliability and accuracy, and low in cost, comprising a motor having a motor shaft reciprocating without rotating according to a pulse number input, a plunger which is fixed to the motor shaft and performs a reciprocating motion, and a sensor combined with a cylinder fixed to a base plate, for detecting the reference position of the plunger.

Description

Specification

Detailed description of the invention

Technical field to which the invention belongs

The present invention relates to a quantitative inhalation and discharge device used when transferring a small amount of liquid. In particular, the present invention relates to a high-precision, high-reliability, inexpensive fixed-quantity suction / discharge device for accurately dispensing liquids such as water and chemical liquids in an automatic analyzer.

Conventional technology

Conventionally, as a method of transferring a very small amount of liquid, a reciprocating movement of a plunger for the liquid suction / discharge device is performed by utilizing a linear movement of a belt between a bull and a pulley using a pulley and a belt. It is known to cause.

As an improved technique, for example, inventing a fixed-quantity pump in Registered Utility Model Publication No. 3015583, a special motor with a shaft that goes straight while rotating, that is, a motor shaft with a thread is rotated. It describes a method of taking out only the linear motion from the motion of the motor shaft to perform the linear motion by directly connecting to the child and rotating it, moving the plunger, and sending the liquid. This improvement eliminates the need for a mechanism to create a new linear motion, eliminates unnecessary rotational motion, achieves significant miniaturization, reduces the number of parts, and enables highly accurate control. Was. Problems to be solved by the invention

However, the conventional rotation-linear conversion mechanism uses a mechanism that interacts with each other in a complicated manner, such as a cup ring and a ball bearing, so that the number of parts is large, and the assembly is complicated and large. was there. In addition, with this conventional mechanism, backlash inevitably occurs, resulting in a decrease in quantitative accuracy. Noh problems also occurred. As a result, in the conventional mechanism, there has been a strong demand for downsizing, a reduction in the number of parts, and an improvement in weighing accuracy associated with the mechanism for converting from rotary motion to linear motion. Further, from the viewpoint of weighing accuracy, the conventional motor cannot completely achieve the conversion of the rotation of the motor output to the linear motion, and the rotation of the rotary shaft of the motor does not correspond to the linear motion of the plunger. This was transmitted slightly, which reduced the accuracy of the plunger stroke. Means for solving the problem

The present invention has been proposed in view of the above circumstances. That is, in order to solve the above-mentioned problem, the present invention incorporates a mechanism having a reciprocating shaft that is coaxial with a motor output shaft, i.e., a rotor, and that performs only reciprocating motion into a constant-rate suction / discharge device. It consists of.

That is, the object of the present invention is to provide a motor which receives an input signal corresponding to the amount of liquid to be sucked or discharged and generates rotation corresponding to the input signal;

Receiving the output rotation of the motor, moving in the axial direction corresponding to the rotation amount in the direction corresponding to the rotation direction of the motor, and coaxially with the rotor of the motor. , Which does not rotate substantially, a reciprocating shaft,

A plunger substantially coaxial with the reciprocating shaft and integrally attached to the reciprocating shaft at one end of the reciprocating shaft;

A cylinder containing the plunger and forming a sealed liquid chamber in front of the plunger for containing the liquid;

A liquid circulation nozzle provided on the side of the cylinder opposite to the plunger of the liquid chamber; and a liquid circulation nozzle connected to the cylinder at a front side of the liquid circulation nozzle. A liquid flow pipe communicating with the liquid, and an opening provided at the tip of the liquid flow pipe for discharging or sucking the liquid. With

The liquid amount corresponding to the rotation of the motor can be achieved by a liquid suction / discharge device configured to discharge or suck in accordance with the rotation direction of the motor.

In a preferred aspect, the outer screw of the reciprocating shaft is reciprocated by screwing with an inner screw provided on the rotor of the motor.

In another aspect, a predetermined filling liquid is filled from the liquid chamber of the cylinder to the inside of the liquid flow pipe, and at least the liquid is sucked and discharged through the port at the time of suction operation. The inside of the chamber has a t ヽ structure in which the target liquid does not flow. More preferably, the output shaft of the motor performs rotation according to the number of input pulses.

Preferably, a movement sensor for detecting movement of the reciprocating shaft in the axial direction is provided. Further, in a specific aspect, a hash and a packing for sealing the liquid chamber are provided at a contact portion with the plunger at an end of the liquid chamber opposite to the nozzle.

According to another feature of the present invention, there is provided a rotating member that rotates by a predetermined amount in a predetermined direction corresponding to an amount of liquid to be sucked or discharged, and a through hole formed in a central portion and extending in a rotation axis direction. A rotating member having an internal screw formed on the inner surface of the

An outer screw threaded through the through-hole of the rotating member, and formed with an outer screw to be fitted with an inner screw of the rotating member, and reciprocating in accordance with the rotation of the rotating member is itself. A reciprocating shaft that does not substantially rotate;

A plunger at one end of the reciprocating shaft, substantially coaxially with the reciprocating shaft, and integrally attached to the reciprocating shaft;

A liquid circulation nozzle provided on the side of the cylinder opposite to the plunger of the liquid chamber A liquid flow pipe connected to the cylinder on the front side of the liquid flow nozzle and communicating with the liquid in the liquid chamber of the cylinder via the nozzle; and a liquid flow pipe provided at a tip end of the liquid flow pipe; Mouth for discharging or inhaling liquid

With

A liquid suction and discharge device is provided which discharges or sucks a liquid amount according to the rotation of the rotating member according to the rotation direction of the rotating member.

In this case, preferably, the reciprocating shaft and the plunger are in a body.

According to the above feature of the present invention, in the liquid suction / discharge device of the present invention, it is not always necessary to directly connect the rotating shaft of the motor and the plunger, and the rotating body is provided outside and the plunger is provided inside. What is necessary is just to comprise the reciprocating shaft directly connected. For example, if the above-mentioned rotating body is connected to the output shaft of the motor so that the motor rotation output can be faithfully reflected, a screw is necessarily cut inside the motor rotor body, and this is screwed to the outer screw of the reciprocating shaft. There is no need to combine.

A feature of the present invention is to provide a liquid suction / discharge device that requires precise quantitative processing by providing a mechanism in which a rotor is provided outside and a motor shaft performs only linear motion without rotating motion. Was made. Typically, a motor having an axis that travels straight without rotating according to the number of pulses input is used, and a simple structure is used to directly connect this motor axis to the plunger, and the number of parts is reduced. And the efficiency of assembly can be reduced. This can further reduce the size and improve the reliability of the liquid quantitative processing. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is an overall configuration diagram of a fixed-quantity suction / discharge device of the present invention.

FIG. 2 is a partial cross-sectional view of the constant-rate suction / discharge device according to the present invention.

FIG. 3 is a cross section of a motor used in the present invention. Embodiment of the Invention

Embodiments of the present invention will be described based on examples with reference to the drawings.

FIG. 1 shows an overall schematic diagram of a micro-liquid inlet / outlet device 1 according to the present invention. In FIG. 1, a liquid suction / discharge device 1 includes a cylinder device 2 having a reciprocating plunger 3, a liquid flow tube 4 connected to the cylinder device 2 and filled with liquid therein, and a tip of the liquid flow tube 4. A suction / discharge unit 5 is provided in the unit for sucking and discharging the liquid. A rotating body drive source 7 (in this example, a motor) having a rotating body 6 that performs a rotating operation corresponding to a predetermined processing liquid amount for causing the plunger 3 of the cylinder device 2 to reciprocate is provided. . An electronic control unit 8, which preferably includes a microcomputer, outputs a drive signal for giving a predetermined rotation of the rotating body 6. The electronic control unit 8 of the present embodiment outputs a predetermined control signal according to the content of the processing and the amount of liquid to be processed. That is, the control device 8 outputs a control signal of the rotating body for controlling the position of the suction / discharge unit 5 and controlling the reciprocation of the plunger 3 of the cylinder device 2.

Referring to FIG. 2 and FIG. 3, the cylinder device 2 and the rotating body drive source 7 (motor) are shown. The rotating body drive source of this example is composed of a motor 7, and the rotor of the motor 7 constitutes the rotating body 6. The cylinder device 2 and the rotating body drive source 7 are fixed on the base plate 10 via bolts 9. In this case, the plunger 3 of the cylinder device 2 rotates the rotating body drive source 7 (motor). Shafts (motor shafts) 11 They are integrally connected to form a common shaft. The cylinder device 2 includes a cylinder body 12 and a plunger 3 slidably disposed in a cylinder bore 13 provided in the cylinder body. A seal member 16 having an O-ring 15 and a spacer 17 are arranged on a step portion of a middle diameter portion 14 extending from an end of the cylinder bore 13 on the plunger base side.

The cylinder body 1 2 extends further from the middle diameter section 14 to the base end side of the plunger 3 The spacer 17 has a large diameter portion 18 having a screw, and the spacer 17 is provided with a seal holding screw 19 screwed to the large diameter portion 18 of the cylinder body 12 with respect to the surface of the stepped portion. It is imposed. Even if the plunger 3 moves within the cylinder bore 13 due to this sealing mechanism, the amount of fluid sucked and discharged from the connection hole 20 is not proportional to the stroke moved by the plunger 3 without sucking and discharging the outside air. Will be. The cylinder bore 13 defines a liquid chamber 22 between the front end face 21 of the plunger 3 and a small-diameter nozzle 23 formed on the opposite side of the liquid chamber 22 from the plunger 3. You. The liquid flow pipe 4 is connected to the front end side of the nozzle 23 via the connection hole 20. The volume of the liquid chamber 22 changes according to the stroke of the plunger 3, and the liquid inside flows through the nozzle 23. In the apparatus to which the present invention is applied, it is required that the stroke of the plunger 3 accurately correspond to the flow rate of the liquid to the liquid chamber 22 via the nozzle 23. It has a liquid-tight structure to withstand this requirement.

The S¾ portion of the plunger 3 is integrally fixed to the non-rotating reciprocating motor shaft 11 of the motor 7 by a fixing screw 25, and the entire end face 21 of the plunger 3 is Move in the cylinder bore 13 by the reciprocating motion of the motor shaft 11. When the plunger 3 slides in the cylinder bore 13, this movement causes the fluid to be more discharged to the bow through the connection hole 14 of the liquid flow pipe 4 at the top of the cylinder.

The light-blocking pin 24 is attached to the plunger 3. The light shielding pin 24 extends in a direction perpendicular to the axial direction of the plunger 3. The position sensor 26 is mounted on the base plate 10. In this case, the position sensor 26 is attached via a support 10a, a lug 10Ob, and a support 10c integrated with the base plate 10. When the light from the light emitting device of the position sensor 26 is blocked by the light-shielding pin 24 and does not reach the light receiving device of the sensor 26, the position indicates the position of the plunger 3 in the predetermined axial direction. Will be. The above position sensor 26 is the axis of this plunger 3. A signal indicating the position in the direction is generated in the control device 8. Thus, the stroke of the plunger 3 and the flow of fluid into and out of the liquid chamber 22 of the cylinder device 2 can be accurately measured by the stroke of the plunger 3 from the reference position. In this case, since the connection between the motor shaft 11 and the plunger 3 is performed integrally, the stroke of the plunger 3 precisely corresponds to the reciprocating movement amount of the motor shaft 11. Therefore, the measurement accuracy can be remarkably improved as compared with the conventional structure. FIG. 3 shows a cross section of a motor in which the shaft 11 reciprocates without rotating. The motor 7 in this example includes a rotor 27 having an internal thread, that is, an internal thread, and the rotor is supported by bearings 28. The externally threaded motor shaft 11 is screwed with a rotating body having a female thread, and the rotating body reciprocates without rotating itself. The rotor 27 is configured to rotate by a magnetic force acting on the stator 29, and when pulse power is applied to the motor 7 in this example, the rotor 27 rotates by a rotation angle corresponding to the number of pulses. That is, reciprocation corresponding to the power supplied to the unit 7 is performed. Note that the control of the rotation direction of the motor 7 can be controlled by a known method, and does not constitute a feature of the present invention.

In the apparatus of this example, a pump was constructed by combining the suction / discharge device according to the present invention with a full stroke of 300 microliters with a three-way solenoid valve, and an experiment was conducted in which water at atmospheric pressure was fed into a pressurized tank at 1 atm. As a result, before and after the operation of 100,000 times, there was almost no change in the liquid supply amount, and it was maintained at 1% or less, and the operation was not stopped due to a failure.In this example, the motor rotor was rotated. Although it is used as a body, an internal screw is cut inside the rotating body and a motor shaft that is screwed with this is provided.

It is not always necessary to use the rotator as a rotating body.

It is also possible to take out the power of the motor rotor and provide another rotating body that receives this rotating power, and use this rotating body to support the reciprocating shaft that is coaxial with the plunger. The invention's effect

The present invention, which has the above-described configuration, provides a fixed-quantity suction / discharge device with a small number of parts, a simple structure, high precision, high reliability, and low cost.

Claims

The scope of the claims

A motor that receives an input signal corresponding to the amount of liquid to be sucked or discharged and generates a rotation corresponding to the input signal;

Upon receiving the output rotation of the motor, the motor moves in the axial direction corresponding to the amount of rotation in a direction corresponding to the rotation direction of the motor, and is coaxial with the rotor of the motor. A reciprocating shaft, which is arranged on the top and does not substantially rotate,

A plunger substantially coaxial with the reciprocating shaft and integrally attached to the reciprocating shaft, at one end of the reciprocating shaft;

A liquid flow nozzle provided on a side of the cylinder opposite to the plunger of the liquid chamber; and a front side of the liquid flow nozzle, connected to the cylinder, through the nozzle, and inside the liquid chamber of the cylinder. A liquid flow pipe that communicates with the liquid, and a port that is provided at a distal end of the liquid flow pipe and that discharges or sucks the liquid,

A liquid suction and discharge device configured to discharge or suck a liquid amount according to the rotation of the motor in accordance with the rotation direction of the motor.

The liquid body according to claim 1, wherein the outer thread of the reciprocating shaft is reciprocated by being screwed with an inner thread provided on the rotor body of the motor. Inhalation and discharge device.

A predetermined filling liquid is filled from the liquid chamber of the cylinder to the inside of the liquid circulation pipe, and at the time of the suction and discharge operation of the target liquid through the opening, at least the inside of the liquid chamber contains the target liquid. 3. The liquid suction / discharge device according to claim 1, wherein the liquid suction / discharge device has a structure in which liquid does not flow.

The output shaft of the motor performs rotation according to the number of input pulses. The liquid suction / discharge device according to any one of claims 1 to 3, wherein:

The liquid suction / discharge device according to any one of claims 1 to 4, further comprising a movement sensor configured to detect movement of the reciprocating shaft in the axial direction. And a gasket and a gasket are provided at a contact portion of the liquid chamber with the plunger at an end of the liquid chamber opposite to the nozzle. A rotating member that rotates by a predetermined amount in a predetermined direction corresponding to the amount of liquid to be sucked or discharged, and a through-hole formed in the center portion and extending in the rotation axis direction. A rotating member having an internal screw formed on the inner surface;

An outer screw which is inserted through the through hole of the rotating member and is screwed with an inner screw of the rotating member is formed. The outer screw itself substantially reciprocates in response to the rotation of the rotating member. And the reciprocating shaft,

A liquid suction and discharge device configured to discharge or suction a liquid amount according to the rotation of the rotating member in accordance with the rotation direction of the rotating member.

The liquid suction and discharge device according to claim 7, wherein the reciprocating shaft and the plunger are bodies.