HK1179567B - Pipette - Google Patents

Description

Suction tube

Technical Field

The present invention relates to a pipette in which a piston in a cylinder having a tip portion detachably attached to a distal end portion is advanced and retreated to suck a liquid into the tip portion of the pipette and discharge the sucked liquid.

Background

For example, as a pipette used for dispensing a liquid such as blood or a drug solution, a so-called disposable pipette is known in which a pipette tip is detachably attached to a pipette and removed after use for the purpose of preventing cross-contamination between liquids.

In such a pipette, in order to prevent contamination of the inside of the cylinder with liquid and scattering of liquid, for example, in the case where the liquid is an infectious sample, it is required to perform a quantitative operation safely at the time of suction/discharge of the liquid in order to prevent infection to a pipette operator and contamination of an inspection environment. Further, it is desirable for the pipette tip portion that has sucked the liquid to be separated and removed from the pipette without touching the hand after discharging the liquid.

Conventionally, as such a pipette, there has been proposed a pipette including a pipette tip separating mechanism in which a suction/discharge amount of a liquid is determined from a moving amount of a piston, and then, as a mechanism for separating and removing the pipette tip from the pipette, the pipette is configured by a sleeve movably fitted to an outer periphery of a cylinder, and an operation unit configured by an operation lever, an arm, a gear, a spring, and the like, and the sleeve is pushed down by an operation of the operation unit to press the sleeve against the pipette tip, thereby separating the pipette tip from a tip of the cylinder (see, for example, patent document 1).

Patent document 1 japanese patent No. 3470150.

Summary of the invention

Problems to be solved by the invention

As described above, in a pipette of this type, the amount of liquid sucked and discharged is generally determined by the amount of forward and backward movement of the piston, as in the pipette described in patent document 1. Therefore, when the suction pipe operator erroneously performs an operation in which the amount of forward and backward movement of the piston exceeds a predetermined size, the amount of liquid sucked exceeds the capacity of the suction pipe tip portion and enters the pressure cylinder during suction of the liquid, thereby contaminating the inside of the pressure cylinder, and the liquid is scattered during discharge of the liquid, so that the suction pipe operator is well versed in the operation of the piston, and careful attention must be paid to the operation of the piston.

Further, it is required to perform a quantitative operation at the time of suction/discharge of the liquid. Further, the pipette described in patent document 1 has a problem that the constitution is complicated and the cost is high because the pipette has a separate pipette tip separating mechanism as a mechanism for separating and removing the pipette tip from the pipette without touching the hand after discharging the liquid from the pipette tip having sucked the liquid.

Disclosure of Invention

The invention provides a straw which can easily, reliably and safely perform quantitative operation of sucking/discharging liquid by simple operation without skillful skill.

Another object of the present invention is to provide a suction pipe capable of preventing liquid from entering a cylinder chamber.

Another object of the present invention is to provide a pipette capable of adjusting the amount of liquid sucked.

Another object of the present invention is to provide a pipette capable of performing suction/discharge of a liquid and separation of a pipette tip portion in a continuous operation.

Another object of the present invention is to provide a pipette capable of preventing scattering of a residual liquid in a pipette tip portion when discharging a liquid and when separating the pipette tip portion from a cylinder.

Another object of the present invention is to provide a pipette capable of preventing the fingers of a pipette operator or gloves worn by the pipette operator from being caught and entangled when separating a pipette tip from a cylinder.

Another object of the present invention is to provide a straw which can be configured simply and at low cost.

Means for solving the problems

In order to achieve the above object, the invention described in claim 1 is a straw comprising: the suction tube is characterized in that a communicating groove is arranged on the periphery of the piston, the communicating groove exists outside the pressure cylinder chamber when the piston is positioned at a retreating position, and communicates the inside and the outside of the pressure cylinder chamber when the advance of the piston exceeds a preset size.

The invention described in claim 2 is the pipette according to claim 1, wherein the amount of liquid sucked by the movement of the piston when the piston moves forward by a predetermined dimension from the retreated position and then retreats to the retreated position is set to be less than the capacity of the liquid in the pipette tip.

The invention described in claim 3 is the invention described in claim 1 or 2, wherein the pipette is provided with a position confirmation mechanism that transmits that the piston has advanced to a predetermined size.

The invention described in claim 4 is characterized in that, in any one of claims 1 to 3, the pipette is provided with a liquid suction amount adjusting mechanism for adjusting a retreat position of the piston.

The invention described in claim 5 is the one according to any one of claims 1 to 4, wherein a release tube is fitted to an outer periphery of the cylinder so as to be movable in an axial direction, the release tube is capable of coming into contact with the pipette tip attached to a tip end portion of the cylinder by moving in a tip end direction, a release portion that moves integrally with the piston is provided in an operation portion that operates the piston, the release portion comes into contact with the release tube to move the release tube in the tip end direction after the piston has advanced beyond a predetermined size, and the pipette tip fitted to the tip end portion of the cylinder is pushed out of the cylinder through the release tube.

The invention described in claim 6 is, in claim 5, characterized in that a flange portion that comes into contact with the detachment portion is formed at a base end of the detachment tube, and a cylindrical protection portion that surrounds the detachment portion is provided at the flange portion.

The invention described in claim 7 is the invention described in any one of claim 5 and claim 6, wherein the piston is integrated with the operating portion and the disengaging portion.

Effective fruit of the invention

According to the suction pipe described in claim 1, since the communication groove that exists outside the cylinder chamber when the piston is at the retracted position and communicates the inside and the outside of the cylinder chamber when the piston advances beyond a predetermined size is provided on the outer periphery of the piston, if the communication groove of the piston that advances into the cylinder chamber reaches the cylinder chamber, the communication groove releases the seal between the cylinder chamber and the piston to communicate the inside and the outside of the cylinder chamber, the pressure in the cylinder chamber becomes equal to the atmospheric pressure, and the suction/discharge action is eliminated. Accordingly, the maximum suction/discharge amount by the advance and retreat of the piston is limited by the dimension from the tip end of the piston to the communication groove, and the suction/discharge of the liquid of a predetermined amount or more can be reliably prevented even if the advance of the piston exceeds the predetermined dimension, so that it is not necessary for a skilled technician to perform the quantitative operation of the suction/discharge of the liquid easily, reliably, and safely with a simple operation.

Further, since the quantitative operation of the suction/discharge of the liquid can be surely performed, the liquid can be prevented from entering the cylinder chamber, and the liquid can be prevented from scattering when the liquid is discharged.

According to the pipette described in claim 2, in claim 1, since the amount of suction of the liquid by the movement of the piston when the piston moves forward by a predetermined dimension from the retracted position and then retracts to the retracted position is set to be less than the capacity of the liquid in the pipette tip, it is possible to prevent the liquid from entering the cylinder chamber during suction of the liquid, and to prevent the cylinder chamber from being contaminated with the liquid.

According to the pipette described in claim 3, in any of claims 1 and 2, since the pipette is provided with the position confirmation means for transmitting the fact that the advance of the piston has reached the predetermined size, the fact that the advance of the piston has reached the predetermined size can be notified to the piston operator, and the quantitative suction of the liquid can be promoted.

According to the pipette of claim 4, in any one of claims 1 to 3, since the pipette is provided with a liquid suction amount adjustment mechanism that adjusts the retreat position of the piston, the amount of liquid suction can be easily and reliably adjusted.

According to the pipette as set forth in claim 5, when the pipette tip is separated after use, the piston is moved forward until the piston exceeds a predetermined size, the separation portion provided in the piston comes into contact with the separation tube to push and move the separation tube in the distal direction, and the separation tube pushed and moved by the separation portion pushes the pipette tip fitted to the distal end portion of the cylinder out of the cylinder, whereby the pipette tip can be separated from the distal end portion of the cylinder.

Since the operation for separating the pipette tip can be performed only by performing the operation of the piston in the same sequential stroke as the operation for sucking and discharging the liquid, the operation is easy, and the operation can be performed in sequential operation with the operation for sucking and discharging the liquid, the configuration for sucking and discharging the liquid and the configuration for separating the pipette tip can use common components, so that the number of components can be reduced, and the manufacturing can be made easy and at low cost.

Further, since the communicating groove which exists outside the cylinder chamber when the piston is at the retreated position and communicates the inside and the outside of the cylinder chamber when the piston advances beyond a predetermined dimension is provided on the outer periphery of the piston, when the pipette tip portion fitted to the tip end portion of the cylinder is pushed out from the cylinder to push the release pipe in the tip end direction and the piston advances beyond the predetermined dimension, the sealing between the cylinder chamber and the piston is released by the communicating groove and the pressure in the cylinder chamber becomes the same as the atmospheric pressure, and therefore even if liquid remains at the pipette tip portion, scattering of the liquid can be prevented when the pipette tip portion separates.

According to the pipette as set forth in claim 6, in any one of claims 5 and 6, since the flange portion abutting against the detachment portion is formed at the base end of the detachment tube and the cylindrical protecting portion surrounding the detachment portion is provided at the flange portion, when the pipette tip portion is detached from the cylinder, it is possible to prevent fingers of the pipette operator or gloves worn by the pipette operator from being pinched and caught between the detachment portion and the flange portion formed at the base end of the detachment tube.

According to the pipette as set forth in claim 7, in any one of claims 5 and 6, since the piston is integrated with the operating portion and the detaching portion, the number of parts can be reduced, the configuration is simplified, and the pipette can be manufactured easily and at low cost.

Drawings

FIG. 1 is a partially cut-away front view showing an example of the embodiment of the straw according to the present invention.

Fig. 2 is a partial cutaway side view of fig. 1.

Fig. 3 is a sectional view taken along line a-a of fig. 1.

Fig. 4 is a sectional view taken along line B-B of fig. 2.

Fig. 5 is a partial cross-sectional view showing another example of the liquid suction amount adjustment mechanism.

Fig. 6 is a cross-sectional explanatory view showing a state where the piston is advanced by a predetermined dimension.

Fig. 7 is a cross-sectional explanatory view showing a state in which the piston exceeds a predetermined size and the inside and outside of the cylinder communicate with each other.

Fig. 8 is a cross-sectional explanatory view showing a state in which the piston exceeds a predetermined size, the detachment tube is pushed in the distal direction, and the suction tube tip is pushed out to prevent the piston from advancing forward.

Fig. 9 is an explanatory diagram showing a state where the pipette tip is separated from the distal end portion of the cylinder.

Description of the reference numerals

1 cylinder, 1a top end portion, 2 cylinder holder, 2a small-diameter cylindrical portion, 2b large-diameter cylindrical portion, 3 pipette tip portion, 3a base portion, 3b top end portion, 4 liquid storage portion, 5 filter, 6 cylinder chamber, 7 piston, 8 operating portion, 8a base portion, 8b plate portion, 8c long piece, 9 retreat position setting means, 10 flange portion, 11 plug body, 12 cylinder portion, 12a end portion, 13 locking portion, 14 spring chamber, 15 spring, 16 seal ring, 17 communication groove, 18 position confirming means, 19 step portion, 20 contact portion, 21 liquid suction amount adjusting means, 22 release tube, 23 flange portion, 24 release portion, 25 guide groove, 26, 27 annular projection portion, 28 advance regulating means, 29 locking portion, 30 boundary step portion, a 31 … protector, a 32 … auxiliary cylinder, BL … seal the cut line.

Detailed Description

Hereinafter, an embodiment of the straw according to the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a partially cut-away front view showing an example of the pipette according to the present invention, fig. 2 is a partially cut-away side view of fig. 1, fig. 3 is a sectional view taken along line a-a of fig. 1, fig. 4 is a sectional view taken along line B-B of fig. 2, fig. 5 is a main sectional view showing another example of the liquid suction amount adjusting mechanism, fig. 6 is a sectional explanatory view showing a state in which a piston is advanced by a predetermined dimension, fig. 7 is a sectional explanatory view showing a state in which the inside and the outside of a cylinder are communicated after the piston exceeds the predetermined dimension, fig. 8 is a sectional explanatory view showing a state in which the piston exceeds the predetermined dimension, a separation tube is pushed in the distal direction to push out the pipette tip and further advance of the piston is prevented, and fig. 9 is an explanatory view showing a state in which the pipette tip is separated from the distal end of the cylinder.

In the straw of this example, a cylindrical cylinder bracket 2 is integrally provided on the base end of the cylinder 1 coaxially with the cylinder 1. Further, a base portion 3a of the suction pipe tip portion 3 is detachably attached to the tip portion 1a of the cylinder 1 in a friction fit manner. The interior of the distal end portion 3b of the suction tube distal end portion 3 attached to the distal end portion 1a of the cylinder 1 is a liquid storage portion 4, and is separated from the base portion 3a by a built-in filter 5.

The cylinder bracket 2 provided integrally with the base end of the cylinder 1 has a small-diameter cylindrical portion 2a on the tip side, which has substantially the same diameter as the base end of the cylinder 1, and a large-diameter cylindrical portion 2b on the base end side.

Further, a piston 7 is fitted to a cylinder chamber 6 formed in the cylinder 1 so as to be able to advance and retreat, and the piston 7 retreats in the cylinder chamber 6 to suck a liquid into the pipette tip 3 attached to the distal end portion 1a of the cylinder 1 and further to discharge the sucked liquid from the pipette tip 3. A rod-shaped operating portion 8 for operating the forward and backward movement of the piston 7 is integrally provided on the proximal end of the piston 7 in the coaxial direction. The operation portion 8 is inserted through the cylinder bracket 2 so as to be movable in the axial direction, and a base end portion 8a thereof protrudes outward from the base end of the cylinder bracket 2.

A retreat position setting mechanism 9 that sets the retreat position of the piston 7 is provided on the inner periphery of the base end of the cylinder bracket 2. In this example, as the retreating position setting means 9, a cylindrical plug body 11 having a flange portion 10 on the outer periphery thereof and allowing the operation portion 8 to freely pass therethrough is fitted and fixed to the inner periphery of the base end of the cylinder bracket 2, a locking portion 13 capable of locking with an end portion 12a of a cylindrical portion 12 fitted in the cylinder bracket 2 is provided on the outer periphery of the operation portion 8, and the position at which the locking portion 13 of the retreating operation portion 8 is locked with the end portion 12a of the cylindrical portion 12 fitted in the cylinder bracket 2 is set as the retreating position of the operation portion 8.

In this example, the plurality of plate-shaped portions 8b are provided radially on the outer periphery of the operation portion 8 in the longitudinal direction of the operation portion 8, and the end portion on the proximal end side of the plate-shaped portion 8b is used as the locking portion 13, as the locking portion 13.

The inside of the small-diameter cylindrical portion 2a of the cylinder bracket 2 communicating with the cylinder chamber 6 formed in the cylinder 1 is a spring chamber 14, and the inner diameter of the spring chamber 14 is larger than that of the cylinder chamber 6. The operation portion 8 provided at the base end of the piston 7 can be inserted into the spring chamber 14 and has substantially the same diameter as the inner diameter of the spring chamber 14.

A spring 15 is assembled in the spring chamber 14, and one end of the spring 15 is locked to a step portion of a boundary between the cylinder chamber 6 and the spring chamber 14, and the other end is locked to a step portion formed between the piston 7 and the operation portion 8, and biases the operation portion 8 in a direction of retreating the piston 7 which is a base end side of the cylinder bracket 2.

Further, the outer periphery of the piston 7 existing outside the cylinder chamber 6 of the piston 7 fitted to the cylinder chamber 6 so as to be movable forward and backward, that is, on the spring chamber 14 side, is slidably fitted to a seal ring 16 that seals between the cylinder chamber 6 and the piston 7. The seal ring 16 is constantly pressed against the boundary step portion between the cylinder chamber 6 and the spring chamber 14 by one end of the spring 15, and seals between the piston 7 and the cylinder chamber 6 and the spring chamber 14.

A communication groove 17 is provided on the outer periphery of the piston 7 that advances and retracts by the operation of the operation portion 8, and exists outside the cylinder chamber 6 when the piston 7 is at the retracted position, and communicates the inside and outside of the cylinder chamber 6, that is, the cylinder chamber 6 with the spring chamber 14 when the piston 7 advances beyond a predetermined size. The communication groove 17 is an elongated groove extending in the axial direction, and when the piston 7 advances beyond a predetermined dimension, the communication groove 17 straddles the cylinder chamber 6 and the spring chamber 14, and the seal ring 16 is positioned on the communication groove 17, so that the communication groove 17 releases the seal between the cylinder chamber 6 and the piston 7, and the inside and the outside of the cylinder chamber 6 communicate with each other.

The predetermined dimension mentioned here is a movement amount that limits the amount of suction in the cylinder chamber 6 by the movement of the piston 7 when the piston 7 at the retracted position is moved forward to a predetermined position and returned from the predetermined position to the retracted position, and is used to set the maximum amount of suction of the liquid. The suction amount at this time is required to be less than the capacity of the liquid storage part 4 in the pipette tip 3.

In this example, a position confirmation mechanism 18 is provided to confirm that the forward movement of the transmission piston 7 has reached a predetermined size. In the position confirmation means 18 of this example, a projecting step portion 19 is formed on the inner peripheral surface of the large diameter cylindrical portion 2b of the cylinder bracket 2 at a position having a predetermined dimension in the forward direction from the retracted position of the piston 7, an abutment portion 20 that abuts against the projecting step portion 19 when the piston 7 is advanced by the predetermined dimension from the retracted position is provided on the operation portion 8, and when the piston 7 is advanced, the piston operator can confirm that the advance of the piston 7 has reached the predetermined dimension by feeling the resistance feeling with which the abutment portion 20 of the operation portion 8 abuts against the projecting step portion 19. The contact portion 20 provided in the operation portion 8 has elasticity and can elastically deform to move the piston 7 further forward beyond the stepped portion 19.

In the present example, the contact portion 20 provided in the operation portion 8 is formed by forming a long groove in the outer edge of the plate-like portion 8b from the distal end side to the proximal end side to form a flexible long piece 8c by using a part of the plurality of plate-like portions 8b provided in the operation portion 8, and a bulging portion is formed at the distal end of the long piece 8c to serve as the contact portion 20.

In this example, a liquid suction amount adjusting mechanism 21 for adjusting the retreated position of the piston 7 is provided. In this example, the plug body 11 serving as the retreat position setting means 9 is used as the liquid suction amount adjusting means 21, and a plurality of plug bodies 11 having different lengths of the tube portion 12 are prepared and used as the liquid suction amount adjusting means 21.

The length of the cylindrical portion 12 of the plug body 11 determines the retreat position of the piston 7, and the amount of liquid suction can be adjusted by changing the length of the cylindrical portion 12 by replacing the plug body 11, thereby changing the stroke amount of the piston 7. The retreating position of the piston is changed by providing a plurality of plug bodies 11 having different lengths of the cylindrical portion 12, and the "predetermined dimension" is set with reference to the maximum retreating position of the piston. That is, the maximum retreated position of the piston is set by the plug body 11 having the shortest cylindrical portion 12, and the retreated position of the plug body 11 having the shortest cylindrical portion 12 is set as a reference for setting the predetermined dimension.

As another example of the liquid suction amount adjustment mechanism 21, as shown in fig. 5, an auxiliary cylindrical body 32 for adjusting the distance between the end 12a and the locking portion 13 may be interposed between the end 12a of the cylindrical portion 12 of the plug body 11 and the locking portion 13 of the operation portion 8. The auxiliary cylinder 32 has an outer diameter smaller than the inner diameter of the cylinder bracket 2 and an inner diameter larger than the outer diameter of the operation portion 8, and is movably fitted to the cylinder bracket 2 on the base portion 8a side of the operation portion 8. One end of the auxiliary cylindrical body 32 can be locked to the locking portion 13 of the operation portion 8, and the other end can be locked to the end 12a of the cylindrical portion 12 of the plug body 11. A plurality of auxiliary cylindrical bodies 32 formed in this way and having different lengths are prepared, and the length of the cylinder is changed by replacing the auxiliary cylindrical body 32, so that the stroke amount of the piston 7 is changed, and the amount of liquid suction can be adjusted.

Further, although not shown, a retreat position setting mechanism 9 that sets a retreat position of the piston 7 is provided on the inner periphery of the base end of the cylinder bracket 2. In this example, as the retreated position setting means 9, a female screw may be formed on the inner periphery of the base end of the cylinder bracket 2, a male screw may be formed on the outer periphery of the cylindrical portion 12 of the plug body 11, and the length of the cylindrical portion 12 of the plug body 11 in the cylinder bracket 2 may be changed by adjusting the amount of screwing the cylindrical portion 12 of the plug body 11 into the inner periphery of the base end of the cylinder bracket 2 in order to achieve a structure in which the cylindrical portion 12 of the plug body 11 is screwed into the inner periphery of the base end of the cylinder bracket 2.

Further, although not shown, as the liquid suction amount adjustment mechanism 21, an operation portion 8 provided with a locking portion 13 that can be locked to the end portion 12a of the cylindrical portion 12 fitted in the cylinder bracket 2 may be used, and a plurality of operation portions 8 having different positions in the longitudinal direction of the locking portion 13 may be prepared, and the stroke amount of the piston 7 may be changed.

The release pipe 22 is fitted to the outer periphery of the cylinder 1 so as to be movable in the axial direction so as to straddle the small-diameter cylindrical portion 2a of the cylinder bracket 2. When the release pipe 22 moves to the distal end side, the distal end thereof abuts on the proximal end of the pipette tip 3 fitted to the distal end portion 1a of the cylinder 1, and the pipette tip 3 is pushed out from the distal end portion 1a of the cylinder 1. A flange 23 is formed on the outer periphery of the base end of the release pipe 22.

Further, the operating portion 8 for operating the piston 7 is provided with a disengaging portion 24 that moves integrally with the piston 7. In the cylinder bracket 2, a guide groove 25 is provided in the axial direction from the boundary between the small-diameter cylindrical portion 2a and the large-diameter cylindrical portion 2b toward the small-diameter cylindrical portion 2a, and a disengaging portion 24 provided in the operating portion 8 protrudes from the guide groove 25 to the outside of the cylinder bracket 2 and moves in the guide groove 25 in accordance with the movement of the piston 7. When the piston 7 advances beyond a predetermined size, the release portion 24 provided in the operation portion 8 abuts against the flange portion 23 at the base end of the release pipe 22, and the release pipe 22 is pushed out toward the tip end side.

At this time, in order to prevent the release pipe 22 pushed out by the release portion 24 from falling off the cylinder 1, annular protrusions 26 and 27 that engage with each other are formed on the outer peripheral surface of the cylinder 1 and the inner peripheral surface of the release pipe 22, respectively.

The disengaging portion 24 provided in the operating portion 8 is provided integrally with the operating portion 8, and in this example, the other plate-shaped portion 8b that is not used as the abutting portion 20 out of the plurality of plate-shaped portions 8b provided in the operating portion 8 is used, and the end portion on the tip end side of the plate-shaped portion 8b is used as the disengaging portion 24.

In this example, the advance restriction mechanism 28 is provided to restrict further advance after the detachment portion 24 provided in the operation portion 8 abuts against the flange portion 23 at the base end of the detachment tube 22 to push out the detachment tube 22 toward the distal end side.

In this example, the advance restriction mechanism 28 is configured such that an engaging portion 29 is provided on the outer periphery of the operation portion 8, and at a position where the release portion 24 pushes out the release pipe 22 toward the distal end side, the engaging portion 29 engages with a boundary step portion 30 between the small-diameter cylindrical portion 2a and the large-diameter cylindrical portion 2b of the cylinder holder 2, and the piston 7 cannot advance any further.

In the present example, the plate-shaped portion 8b used as the abutting portion 20 out of the plurality of plate-shaped portions 8b provided in the operation portion 8 is used as the locking portion 29 provided in the operation portion 8, and the end portion on the tip end side of the plate-shaped portion 8b is used as the locking portion 29.

In this example, the flange portion 23 formed at the base end of the release pipe 22 is provided with a cylindrical protection portion 31 that protrudes from the guide groove 25 to the outside of the cylinder bracket 2 and surrounds the release portion 24 that moves in the guide groove 25 in accordance with the movement of the piston 7.

When the pipette of the above-described configuration is not in use, the piston 7 is biased by the spring 15 to be positioned at the retreated position. In use, the distal end portion of the suction tube distal end portion 3 fitted to the distal end portion 1a of the cylinder 1 is inserted into a liquid to be sucked, and the base portion 8a of the operation portion 8 protruding to the outside from the proximal end of the cylinder bracket 2 is pushed toward the distal end side against the elastic force of the spring 15.

After the piston 7 is moved forward, if the pushing-in of the operation portion 8 is released, the piston 7 is returned to the retreated position by the elastic force of the spring 15, and the liquid is sucked to the pipette tip portion 3 fitted to the tip end portion 1a of the cylinder 1 by the suction action of the piston 7 and is stored in the liquid storage portion 4. At this time, since the amount of suction of the liquid by the movement of the piston 7 when the piston 7 moves forward from the retreated position to the retreated position after advancing by a predetermined dimension is set to be less than the storage capacity of the liquid storage section 4, the liquid can be prevented from entering the cylinder chamber 6 at the time of suction of the liquid.

It is desirable that the amount of movement for advancing the piston 7 does not exceed a predetermined size set in advance. In this example, since the position confirmation means 18 for transmitting the fact that the advance of the piston 7 has reached the predetermined size is provided, the piston operator can be notified of the fact that the advance of the piston 7 has reached the predetermined size, and the suction/discharge of a fixed amount of liquid can be promoted.

In the present example, the position confirmation mechanism 18 is configured such that the piston operator can confirm that the advance of the piston 7 has reached the predetermined dimension by feeling the resistance of the abutting portion 20 provided in the operation portion 8 abutting against the stepped portion 19 formed on the inner peripheral surface of the large-diameter cylindrical portion 2b of the cylinder bracket 2, and therefore, the advance of the piston 7 having reached the predetermined dimension can be reliably transmitted to the piston operator.

Even if the advance of the piston 7 exceeds the predetermined size, the communication groove 17 for communicating the inside and the outside of the cylinder chamber 6 when the advance of the piston 7 exceeds the predetermined size is provided on the outer periphery of the piston 7, so that the pressure in the cylinder chamber 6 becomes equal to the atmospheric pressure, and the suction/discharge action is lost. Accordingly, the maximum suction/discharge amount of the liquid by the advance and retreat of the piston 7 is limited by the dimension from the distal end of the piston 7 to the communication groove 17, and suction/discharge of the liquid of a predetermined amount or more can be reliably prevented even if the advance of the piston 7 exceeds the predetermined dimension.

The position shown by the one-dot chain line in fig. 6 to 8 is a seal-cut line BL where the seal between the cylinder chamber 6 and the piston 7 is released by the communication groove 17, and if the communication groove 17 reaches the seal-cut line BL, the inside and the outside of the cylinder chamber 6 communicate with each other.

In this example, since the liquid suction amount adjustment mechanism 21 for adjusting the retreat position of the piston 7 is provided, the suction amount of the liquid can be easily and reliably adjusted. In this example, the stopper body 11 serving as the retreat position setting means 9 is used as the liquid suction amount adjusting means 21, and the stopper bodies 11 having different lengths of the plurality of cylindrical portions 12 are prepared and used as the liquid suction amount adjusting means 21, so that the suction amount of the liquid can be adjusted by a simple operation of replacing the stopper body 11.

The liquid in the liquid storage portion 4 stored in the pipette tip 3 in this way is discharged from the pipette tip 3 by pushing the base portion 8a of the operation portion 8 protruding outward from the base end of the cylinder holder 2 toward the distal end side, and is dispensed into a predetermined container or the like.

When the pipette tip 3 is separated from the tip end 1a of the pressure cylinder 1 after dispensing of the liquid is completed, the base 8a of the operation unit 8 for operating the piston 7 is pushed into the pressure cylinder holder 2, and the piston 7 is advanced beyond a predetermined size, in the same manner as in the suction and discharge of the liquid. When the piston 7 advances beyond a predetermined size, the release portion 24 that moves integrally with the operation portion 8 comes into contact with the flange portion 23 at the base end of the release pipe 22, the release pipe 22 is pushed out toward the tip end side, and the suction pipe tip portion 3 fitted to the tip end portion 1a of the cylinder 1 is pushed out by the movement of the pushed-out release pipe 22. Thus, the pipette tip 3 can be easily separated from the distal end portion 1a of the cylinder 1 without touching the pipette tip 3 with a hand.

The operation for separating the pipette tip 3 can be performed by the same consecutive stroke as the operation for sucking/discharging the liquid by the piston 7.

In this example, the flange portion 23 formed at the base end of the release pipe 22 is provided with the cylindrical protective portion 31 that protrudes from the guide groove 25 to the outside of the cylinder bracket 2 and surrounds the release portion 24 that moves in the guide groove 25 in accordance with the movement of the piston 7, so that when the pipette tip portion 3 is separated from the cylinder 1, the fingers of the pipette operator or gloves worn by the pipette operator can be prevented from being pinched and caught between the release portion 24 and the flange portion 23 formed at the base end of the release pipe 22.

Further, since the communicating groove 17 that communicates the inside and the outside of the cylinder 1 when the piston 7 moves forward beyond the predetermined dimension is provided on the outer periphery of the piston 7, when the piston 7 moves forward to exceed the predetermined dimension in order to push the suction tip portion 3 out of the distal end portion 1a of the cylinder, the sealing between the cylinder chamber 6 and the piston 7 can be released by the communicating groove 17, and the pressure in the cylinder chamber 6 becomes equal to the atmospheric pressure, so that even if liquid remains in the suction tip portion 3, the liquid can be prevented from scattering when the suction tip portion 3 is separated.

Further, in this example, the piston 7, the rod-shaped operating portion 8 for operating the advance and retreat of the piston 7, and the escape portion 24 for contacting the escape tube 22 and moving the escape tube 22 in the distal direction are integrated, so that the number of components can be reduced, the configuration is simple, and the manufacturing can be facilitated and the cost can be reduced.

Claims (7)

1. A straw, comprising: a cylinder having a tip portion of a pipette detachably attached to a distal end portion thereof, and a piston fitted in a cylinder chamber so as to be movable forward and backward, wherein the piston is moved backward to suck a liquid and moved forward to discharge the sucked liquid,

a communication groove is provided on the outer periphery of the piston, the communication groove being present outside the cylinder chamber when the piston is in the retracted position and communicating the inside and outside of the cylinder chamber when the piston has advanced beyond a predetermined dimension.

2. The pipette according to claim 1,

the amount of liquid sucked by the movement of the piston when the piston moves forward by a predetermined dimension from the retreated position and then retreats to the retreated position is set to be less than the capacity of the liquid in the pipette tip.

3. The drinking straw according to claim 1 or 2,

the pipette is provided with a position confirmation mechanism for transmitting the advance of the piston to a predetermined size.

4. The drinking straw according to claim 1 or 2,

the suction pipe is provided with a liquid suction amount adjusting mechanism for adjusting the retraction position of the piston.

5. The drinking straw according to claim 1 or 2,

a release pipe is fitted to an outer periphery of the cylinder so as to be movable in an axial direction, the release pipe being capable of coming into contact with the pipette tip attached to the distal end portion of the cylinder by moving in a distal direction, a release portion that moves integrally with the piston is provided in an operation portion that operates the piston, and the release portion comes into contact with the release pipe to move the release pipe in the distal direction when the piston moves forward beyond a predetermined size, whereby the pipette tip fitted to the distal end portion of the cylinder is pushed out from the cylinder through the release pipe.

6. The pipette according to claim 5,

a flange portion that abuts the detachment portion is formed at a base end of the detachment tube, and a cylindrical protection portion that surrounds the detachment portion is provided at the flange portion.

7. The pipette according to claim 5,

the piston is integrated with the operation portion and the disengagement portion.