JP2008253980A - Pipette and its plunger sealing mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipette and its plunger sealing mechanism whose suction capacity and discharge capacity can be variably set if and when the sliding part thereof is worn away after repeated use. <P>SOLUTION: The plunger sealing mechanism is equipped with an O-ring holding ring 101 fitted to a plunger 29, a seal-ring 102 fitted to the plunger 29, an O-ring 103 inserted between the O-ring holding ring 101 and the seal-ring 102, and an O-ring pressing spring 104 for pressing the O-ring holding ring 101 in the axial direction with a predetermined force to press the O-ring 103 to the tilting inner face 121a of a cylinder member 121 and to press the seal-ring 102 in the radial direction inwardly relative to the outer circumferential face of the plunger 29 by virtue of the orthogonal component of the predetermined force relative to the axial direction, wherein the tilt angle α of the tilting inner face 121a is 40° to 65° relative to the direction orthogonal to the axis of its pipette. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipette and plunger plunger seal mechanism capable of variably setting suction and discharge capacities.

Conventional technology

  As an example of a conventional variable pipette, a resin-made substantially cylindrical body or pipette body (having a sampling chamber, i.e., a cylinder chamber at the lower end), and an outer peripheral screw portion screwed into an inner peripheral screw of the pipette main body A metal sheath having a hexagonal central push rod inserted non-rotatably and axially slidable with respect to the central hexagonal hole of the metal sheath, and first and second below the push rod. A piston rod urged upward by a coil spring (hereinafter referred to as a first-stage spring and a second-stage spring) and brought into contact with the lower end of the push rod and a piston integrated therewith are coaxially arranged.

In the above configuration, the push rod is pushed down integrally with the piston against the first-stage spring, and is slid back and forth by the first-stage stroke l ₁ against the first-stage spring, and is a disposable nozzle attached to the lower end of the pipette body. The sample is sucked into the (chip), and then the push rod is pushed down again for the above dimension l ₁ minute to discharge the sample. When the push rod is further pushed down, it slides downward by the second step stroke l ₂ against the second step spring in addition to the first step spring, and the sample remaining in the chip by this second step discharge. Is completely discharged.

  Next, in order to variably set the suction volume of the sample, when the metal sheath is rotated in a predetermined direction, the metal sheath is moved upward by a predetermined amount by screwing between the outer peripheral screw portion of the metal sheath and the inner peripheral screw portion of the pipette body. Alternatively, it can be moved downward to adjust the vertical movement stroke of the piston in an increasing or decreasing direction.

  Simultaneously with the suction volume variable setting by rotating the metal sheath in a predetermined direction, the suction volume numerical display body is driven in an interlocked manner to display the variably set suction volume numerical value.

  (1) According to the configuration of the above conventional example, the first stage spring is provided below the push rod. Therefore, when the push rod moves downward, for example, when the suction capacity is variably set by the metal sheath, the piston rod also moves in the same direction. The first stage spring is compressed by the moving distance. Therefore, for example, when the suction capacity is set to be small, the load of the first-stage spring gradually increases, and the push rod operation becomes heavy.

  (2) Moreover, the initial length of the first stage spring itself, that is, the initial load (that is, the weight feeling when the push rod is pushed down) cannot be variably set.

  (3) Further, since the tip attaching / detaching portion at the lower end of the pipette body to which the tip is attached is made of a resin, there is a problem that wear occurs when the tip is repeatedly attached and detached in a complicated manner. In addition, the outer periphery of the tip attachment / detachment portion at the bottom end of the pipette body is simply a circular shape, so that when the tip is completely fitted, the fitting adhesion is increased, and the load that is manually ejected by the eject mechanism becomes relatively large, making operation difficult. There was a problem.

  (4) The pipette made of resin has a problem that, when the pipette body is held by a hand for a long time, the heat of the hand is conducted to the inside and the suction capacity is unstablely changed.

  (5) Since there are various types of chips, the distance between the lower end of the ejector pipe and the chip varies variously. In the case of a chip having a large distance, the ejector is operated to operate the ejector. In some cases, the tip could not be ejected well even when the pipe was lowered.

  (6) When the suction volume numerical display of the suction volume display mechanism deviates from the actual suction volume, so-called calibration is performed to change the suction volume numerical display. For this purpose, the display mechanism as a unit structure is temporarily pipetted. There is a problem that it is very troublesome because it is necessary to detach it and then re-install it after performing numerical display adjustment and performing calibration, or a dedicated jig for performing calibration.

  (7) In the cylindrical body, the plunger is moved between the plunger (piston rod) which is moved up and down together with the central shaft (central push rod) and the cylindrical cylinder member into which the plunger is slidably fitted. In the plunger seal mechanism provided with an O-ring that seals the outer peripheral surface, the O-ring is pressed against the inclined surface of the cylindrical cylinder member by a spring. The inclination angle β of this inclined surface is in the direction perpendicular to the axis of the pipette. About 5 ° (β = 5 °; see FIGS. 25, 31 and 32).

  Therefore, as is apparent from FIG. 32, when it is assumed that the spring force P for pressing the O-ring (not shown) in the axial direction is 307.6 g which is the same as that of the present invention described later, the decomposed force q And r are 308.78 g and 26.91 g, respectively. Particularly, the component r (26.91 g) in the direction perpendicular to the axis is extremely small, and the force with which the O-ring presses the plunger radially inward, that is, the sealing force is small. I understand that. Therefore, when wear occurs in the sliding portion due to repeated use, the airtightness cannot be maintained relatively early, and if liquid leaks from there, there is a possibility that the pipetting accuracy is lowered.

  The configuration of the present invention for solving the above-described problem is that a pipette has a cylindrical body 1 having a first threaded portion 1b and a second threaded portion 5c that is screwed into the first threaded portion 1b. A stroke screw 5 disposed in the body 1, a variable capacity setting member 4 that is integrally rotatable with the stroke screw 5 and is slidable in the axial direction, and the plunger in the cylindrical body 1. 29 is connected to the central shaft 7 and is arranged so as to be able to be pushed down. The central shaft 7 is interposed between the upper portion of the central shaft 7 and the stroke screw 5 to urge the central shaft 7 upward to have a predetermined portion. A first-stage spring 10 that urges the stroke screw 5 against the stroke screw 5, and appropriately rotates the variable capacity setting member 4 to rotate the stroke screw 5 integrally with the body 1. , Said su Rokuneji 5 and a central shaft 7 is slid by the integrally predetermined amount apparent in the axial direction, characterized in that for variably setting the suction capacity.

According to another configuration of the present invention, the pipette includes a substantially cylindrical body 1 having a first threaded portion 1b and a second threaded portion 5c that is screwed into the first threaded portion 1b. A clutch member 3 having a stroke screw 5 disposed within the first engaging portion 3a, a first engaging portion 3a, and being arranged so as to be integrally rotatable with the stroke screw 5 and slidable in the axial direction; A variable capacity setting member 4 having a joint portion 4b and disposed so as to be integrally rotatable when the first and second engaging portions 3a and 4b are engaged with the clutch member 3;
A central shaft 7 connected to the plunger 29 in the cylindrical body 1 and arranged so as to be able to be pushed down is interposed between the upper portion of the central shaft 7 and the stroke screw 5 so that the central shaft 7 is inserted. A first-stage spring 10 that urges upward to urge the predetermined portion 7b against the stroke screw 5, and appropriately rotates the capacity variable setting member 4 to The stroke screw 5 is integrally rotated, and the suction screw is variably set by sliding the stroke screw 5 and the central shaft integrally in the axial direction by a predetermined amount.

  According to another configuration of the present invention, the pipette has a substantially cylindrical body 1 having a first threaded portion 1b and a second threaded portion 5c that is screwed into the first threaded portion 1b. A stroke screw 5 disposed inside, a central shaft 7 connected to the plunger 29 in the cylindrical body 1 and disposed so as to be able to be pushed down; and a third threaded portion 8a; A first-stage spring load variable member 8 provided on the upper portion of the shaft 7 so as to be relatively rotatable, and a fourth screw portion 9a that is screwed into the third screw portion 8a. A single-stage spring expansion / contraction setting member 9 that is non-rotatable and slidable in the axial direction is interposed between the upper portion of the central shaft 7 and the stroke screw 5 to urge the central shaft 7 upward. The predetermined portion 7b is biased to the stroke screw 5. A first-stage spring 10 to be contacted, and the first-stage spring expansion / contraction setting member 9 with respect to the body 1 in the axial direction by appropriately rotating the first-stage spring load variable member 8. The total length of the first stage spring 10 is variably expanded and contracted by sliding.

According to another configuration of the present invention, in a pipette having a resin cylindrical housing 1 or 21, a ceramic nozzle tip 24 is integrally insert-molded at the tip of the cylindrical housing 1 or 21. It is characterized by being.
Preferably, the ceramic nozzle tip 24 is insert-molded with a stretchable layer 36 of rubber or elastomer at a predetermined location 24c before insert molding into the cylindrical housing 1 or 21.

Preferably, the ceramic nozzle tip 24 has an uneven portion 24a formed on the outer periphery.
According to another configuration of the present invention, a pipette having a cylindrical body 1 is characterized in that the material of the cylindrical body 1 is a fine foam molding material.
Preferably, the fine foam molding material is polyphenylsulfone.
A pipette characterized by that.

  According to another aspect of the present invention, in a pipette having a tip ejector mechanism, the ejector mechanism 32 includes at least an eject button 33, an upper ejector pipe 41, and a lower ejector pipe 42 that presses the tip 46. The first engaging portion 41a provided on one of the upper ejector pipe 41 and the lower ejector pipe 42 is switched and engaged with any of the plurality of second engaging portions 42c, 42d, 42e provided on the other. Thus, the tip position of the lower ejector pipe 42 can be varied.

  In another configuration of the present invention, the pipette has a cylindrical body 1, a stroke screw 5 that is disposed in the body 1 and variably sets the suction capacity, and a first engagement portion 3a. The clutch member 3 is arranged so as to be integrally rotatable with respect to the shaft 5 and is slidable in the axial direction, and has a second engaging portion 4b. A calibration member 4 arranged so as to be integrally rotatable only when the two engaging portions 3a and 4b are engaged, and a central shaft connected to the plunger 29 in the cylindrical body 1 so as to be able to be pushed down. 7 and an inhalation volume display counter mechanism 51 that can be interlocked with the calibration member 4, and the first and second engagements by sliding the calibration member 4 in the axial direction. By appropriately rotating in a state where the engagement of 3a and 4b is released, the stroke screw 5 is not rotated at all, and only the counter mechanism 51 is operated to calibrate the suction capacity numerical value display. And

  In another configuration of the present invention for solving the above-described problem, in the pipette, the central shaft 7 disposed in the cylindrical body 1 so as to be movable up and down integrally with the plunger 29 is provided with at least a first-stage spring 10. A pipette plunger seal mechanism provided between the plunger 29 and a cylindrical cylinder member 121 into which the plunger 29 is slidably fitted. An O-ring holding ring 101 fitted to the plunger 29, a seal ring 102 fitted to the plunger 29, and an O-ring 103 interposed between the O-ring holding ring 101 and the seal ring 102 Then, the O-ring holding ring 101 is pressed in the axial direction with a predetermined force so that the O-ring 103 is pressed into the cylindrical cylinder member 12 An O-ring pressing spring 104 that presses against the inclined inner surface 121a and presses the seal ring 102 radially inward with respect to the outer peripheral surface of the plunger 29 by a component force perpendicular to the axis of the predetermined force. The inclination angle α of the inclined inner surface 121a is 40 ° to 65 ° with respect to the direction perpendicular to the axis of the pipette.

Preferably, the inclined angle α of the inclined inner surface 121a is 50 ° with respect to the direction perpendicular to the axis of the pipette.
Preferably, the seal ring 102 has one or a plurality of circumferential grooves 102c on the inner peripheral surface of the seal portion 102a fitted to the outer peripheral surface of the plunger 29.

Effects of the present invention

  (1) According to the above configuration of the present invention, the first-stage spring 10 is disposed not between the stroke screw 5 but the upper stroke screw 5 and the push button 6. The stage spring 10 moves in the vertical direction with the entire length of the spring itself remaining constant. Therefore, the initial load of the first-stage spring 10 remains constant during the above movement, and there is no inconvenience that the first-stage spring is compressed and the load increases and the button operation becomes heavy as in the conventional example. The operation remains light and does not fluctuate.

  (2) Further, in order to vary the initial length of the first stage spring 10 itself, that is, the initial load (that is, the weight feeling when the shaft 10 is pushed down), by rotating the first stage spring load variable pipe 8, When the inner peripheral screw 8a of the pipe 8 and the outer peripheral screw 9a of the first-stage spring expansion / contraction setting plate 9 are screwed together, the first-stage spring expansion / contraction setting plate 9 moves in the axial direction to expand / contract the first-stage spring 10 and It can be variably set, and this makes it convenient to adjust the feeling (weight) when the push button 6 is depressed.

  (3) Since the nozzle tip 24 to which the tip 46 is attached is made of ceramic, it has high wear resistance, and even if the tip 46 is repeatedly attached and detached, there is no wear and high durability. Further, since the outer peripheral surface of the nozzle tip 24 is formed with, for example, an uneven portion 24a that is undulated in the axial direction, the friction load between the nozzle tip 24 and the tip 46 is small, and the load when ejecting the tip 46 may be small. Eject operation is easy.

The uneven portion 24a is not limited to the undulation in the axial direction, but may be undulated in the radial direction or in other directions.
In addition, a rubber or elastomer stretch layer 36 (see FIG. 23) is inserted into the outer peripheral groove 24c of the insert molding portion 24b for the cylindrical cylinder 21 (or the cylindrical body 1) of the nozzle tip 24 for the first time. Thereafter, this portion is second insert-molded into the cylindrical cylinder 21. As a result, even if the pipette is heated by autoclaving to produce a thermal expansion differential gap between the cylindrical cylinder 21 and the nozzle tip 24, the stretchable layer 36 absorbs the gap and provides a strong assembling force between them. Can hold.

  (4) Since the cylindrical body 1 is made of a fine foam molding material such as polyphenylsulfone, the heat of the hand is difficult to be transferred to the inside of the pipette when the body 1 is gripped by hand. Fluctuation in inhalation volume due to the effects of

  (5) The first engaging portion provided in one of the upper ejector pipe 41 and the lower ejector pipe 42 can be switched and engaged with any of a plurality of second engaging portions provided in the other, and the lower Since the lower end position of the ejector pipe 42 can be changed, even if a tip 46 having various standard dimensions is attached to the outer periphery of the nozzle tip 24, the lower end position of the lower ejector pipe 42 can be adjusted accordingly. Therefore, the eject operation can be performed smoothly and the application range can be expanded.

  (6) The calibration pipe 4 is set in a variable capacity setting and the calibration pipe 4 is forcibly moved in the axial direction to release the engagement between the clutch pawl 4b of the calibration pipe 4 and the engagement gear portion 3a of the clutch pipe 3. By rotating 4, it is possible to calibrate by driving the counter mechanism 51 and changing only the numerical value display without changing the actual suction volume. Can be calibrated.

  (7) The O-ring pressing spring 104 presses the O-ring 103 against the inclined inner surface 121a of the cylindrical cylinder 121 with a predetermined (axial direction) force, and the axial orthogonal component of the predetermined force (radial inward force) ), The seal ring 102 is pressed against the outer peripheral surface of the plunger 29, and the inclination angle α of the inclined inner surface 121a is 40 ° to 65 ° with respect to the direction perpendicular to the axis of the pipette. The plunger pressing force (R; see FIG. 31 and FIG. 32) is increased as compared with the one having a temperature of about 0 °, so that the sealing performance can be improved and the wear-resistant material suitable as the material of the seal ring 102 By selecting, the life of the seal ring 102 can be improved.

  (8) When the inclination angle α of the inclined inner surface 121a is inclined by 50 ° with respect to the pipe orthogonal axis, the maximum sealing performance and the maximum seal life are maintained while maintaining the smooth sliding motion of the plunger 29. Can be obtained.

  (9) Since the seal ring 102 has one or a plurality of circumferential grooves 102 c on the inner peripheral surface fitted to the outer peripheral surface of the plunger 29, first, when the predetermined (axial) force increases, the plunger 29 Although the sliding frictional resistance tends to increase, the inner circumferential groove 102c can reduce the area of the contact surface and suppress the increase of the sliding frictional resistance. Secondly, even if the seal portion 102a and the plunger 29 are worn by sliding friction and wear powder is generated, the wear powder is stored in the inner circumferential groove 102c so that the wear powder remains on the sliding surface. It prevents further progress of wear due to the abrasive effect of the wear powder when assumed.

  1A is an enlarged longitudinal sectional view of the upper half of one embodiment of the pipette according to the present invention, FIG. 1B is an enlarged longitudinal longitudinal sectional view of the lower half thereof, and FIGS. 2 and 3 are respectively pushed down one stage and two stages of the pipette. It is a longitudinal view of a state. In FIG. 4 and subsequent figures, the left side in the figure basically corresponds to the upper side in FIGS. 1 to 3, and the right side in the figure corresponds to the lower side in FIGS. 1 to 3.

  1 and 4, reference numeral 1 denotes a cylindrical body of the variable pipette according to the present invention, which is provided with screw holes 1b and 1c coaxially with a central hole 1a and has an ejector shaft hole 1d. Since this cylindrical body 1 is made of a fine foam molding material such as polyphenylsulfone, for example, when the body 1 is grasped by hand, the heat of the hand is difficult to be transferred to the inside of the pipette. Fluctuation in inhalation volume due to the effects of

1 and 5, a central partition 2 is inserted and fitted into the central hole 1a of the cylindrical body 1 and has a central through hole 2a and other through holes 2b to 2d.
1 and 6, a cylindrical clutch pipe 3 is inserted into the central through hole 2a of the central partition wall 2, and as shown in FIG. 6, a left end (upper end) meshing gear portion 3a and a pair in the inner peripheral axial direction. Guide ridges 3b.

  Reference numeral 4 denotes a variable capacity setting and calibration pipe, which is fitted to the outer periphery of the clutch pipe 3 in FIG. 1, and is circumferentially positioned at predetermined positions in the axial direction of the right end (lower end) outer peripheral gear portion 4a and the inner periphery as shown in FIG. A clutch pawl 4b (possibly meshed with the meshing gear portion 3a of the clutch pipe 3) is provided at the four-divided position. The variable capacity setting and calibration pipe 4 is moved downward in FIG. 1 by a pipe pressing spring 13 interposed between the outer peripheral gear portion 4a and a body lock 12 screwed into the left end (upper end) of the cylindrical body 1. In this state, the outer peripheral gear portion 4a meshes with a pinion portion 59a of a transmission gear 59 (see FIG. 21), and at the same time, the clutch pawl 4b engages with the meshing gear portion of the clutch pipe 3. Meshes with 3a.

  Reference numeral 5 denotes a stroke screw, which is integrated with a stroke screw rod portion 5 a and a stroke screw cylindrical portion 5 b in FIGS. 1 and 8 and is inserted into the inner periphery of the clutch pipe 3. At this time, the outer peripheral screw 5 c of the flange portion 5 a is screwed into the screw hole 1 b of the cylindrical body 1, and the axial guide groove 5 d of the cylindrical portion 5 b is engaged with the guide protrusion 3 b of the clutch pipe 3.

  As a result, when the capacity variable setting and the calibration pipe 4 are rotated, for example, clockwise when viewed from above, the clutch pipe 3 integrally rotates in the same direction via the engagement of the clutch pawl 4b and the meshing gear portion 3a. Further, the stroke screw 5 is integrally rotated in the same direction through the engagement of the guide groove 5d and the guide protrusion 3b, whereby the stroke screw 5 (and a central shaft 7 to be described later) is engaged through screwing of the screw portions 5c and 1b. And the plunger 29) moves downward in FIG. 1 to variably set the first stroke L1 to be small, that is, to reduce the suction capacity of the cylinder chamber 21b. When the volume is variably set and the calibration pipe 4 is rotated counterclockwise, the suction volume is variably set to be large. When the capacity variable setting and the calibration pipe 4 are rotated to variably set the suction capacity, the counter mechanism 51, which will be described later, is simultaneously engaged by the meshing of the outer peripheral gear part 4a and the pinion part 59a of the transmission gear 59 (see FIG. 21). Variably displays a numerical value corresponding to the variably set capacity.

  Reference numeral 6 denotes a push button (having a cylindrical portion 6a, a pair of axial guide slits 6b and a tip claw portion 6c, as shown in FIG. 9), and a central shaft 7 (as shown in FIG. 10, large at the right end (lower end)). The push button 6 is variably set and calibrated with a screw 16 (see FIG. 1) coaxially to a diameter portion 7a, its stopper step portion 7b, a flange portion 7c, and a pair of convex portions 7d). Inserted into the pipe 4 and the central shaft 7 is positioned through the central hole 5e of the stroke screw 5.

  A single-stage spring load variable pipe 8 has an inner peripheral screw 8a as shown in FIG. 11, and is engaged with and fitted to the outer periphery of the cylindrical portion 6a of the push button 6 by a tip claw portion 6c. 9 is a substantially I-shaped one-stage spring expansion / contraction setting plate, as shown in FIG. 12, having a pair of outer peripheral threaded portions 9a and being fitted to the central shaft 7, a pair of shafts of the push button 6. The outer peripheral threaded portion 9 a is inserted into and engaged with the direction guide slit 6 b and is screwed into the inner peripheral screw 8 a of the first-stage spring load variable pipe 8. Reference numeral 10 denotes a one-stage spring which is fitted to the outer periphery of the central shaft 7 in FIG. Reference numeral 11 denotes a button cover. Reference numeral 15 denotes a lid body.

  Accordingly, the push button 6 and the central shaft 7 are urged upward in FIG. 1 by the first spring 10 so that the large-diameter stopper step 7b of the central shaft 7 abuts against the flange 5a of the stroke screw 5. Yes.

  Next, reference numeral 21 denotes a resin-made cylindrical cylinder, which, as shown in FIG. 13, has a large diameter portion 21a, a cylinder chamber 21b, and a passage 21d for the nozzle portion 21c sequentially from the left, and a nozzle at the right end (lower end). The chip 24 is integrally formed by insert molding. The cylindrical cylinder 21 is inserted into a lower end (right end) screw hole 1c of the cylindrical body 1, and is fixed by a lock nut 22 (see FIG. 1). A cylindrical seal retainer 23 has a pair of cutout holes 23 a as shown in FIG. 14 and is arranged on the inner periphery of the large-diameter portion 21 a of the cylindrical cylinder 21. Reference numeral 24 denotes a ceramic nozzle tip (see FIG. 15), which is integrally insert-molded at the right end of the nozzle portion 21c of the cylindrical cylinder 21 as shown in FIG. Reference numeral 25 denotes a filter case in which a fibrous filter is housed, and the sample liquid sucked into the tip 46 (see FIG. 1) is sucked into the nozzle tip 24 and the passage 21d of the nozzle portion 21c. Is prevented. This is because if they are inhaled in these and remain attached even in a small amount, they will be mixed and contaminated when different types of liquid are inhaled next time.

The cylindrical cylinder 21 may be formed as a cylindrical housing formed integrally with the cylindrical body 1 in advance.
According to the above configuration, since the nozzle tip 24 is made of ceramic, the wear resistance is high, and even if the tip 46 described later is repeatedly attached and detached, there is no wear and the durability is high. Further, since the outer peripheral surface of the nozzle tip 24 is formed with an uneven portion 24a undulating in the axial direction, the friction load between the nozzle tip 24 and the tip 46 is small, so the load when ejecting the tip 46 is small, and the eject Easy to operate.

  In addition, a rubber or elastomer stretch layer 36 (see FIG. 23) is inserted into the outer peripheral groove 24c of the insert molding portion 24b of the nozzle tip 24 with respect to the cylindrical cylinder 21 in advance for the first time. A second insert molding is performed on the cylinder 21. The reason for this is that when autoclaving to sterilize the pipette, it is heated to about 120 ° C., and as a result, the resin cylindrical cylinder 21 expands more thermally than the ceramic nozzle tip 24. There is a possibility that a gap is created between the two and the assembly force of the insert molding portion 24b is weakened. For this reason, the stretchable layer 36 is interposed between the two to absorb the gap, thereby preventing the gap and maintaining a strong assembling force between the two.

  Next, reference numeral 26 denotes a cylindrical plunger head having left and right holes 26a and 26b and a pair of axial recesses 26c as shown in FIG. The plunger head 26 is disposed on the inner periphery of the cylindrical seal retainer 23 with a ring-shaped two-stage spring retainer 27 (see FIG. 17) interposed therebetween, and the large diameter of the central shaft 7 is located in the left (upper) hole 26a. The portion 7a is inserted through the plunger head spring 28, and at the same time, the pair of convex portions 7d of the central shaft 7 is engaged with the pair of axial recesses 26c, and is also inserted into the right (lower) hole portion 26b. Plunger 29 (see FIG. 18) is press-fitted. The two-stage spring retainer 27 is engaged with a pair of cutout holes 23a (see FIG. 14) of the cylindrical seal retainer 23 in a pair of ears 27a, but is urged upward in FIG. In contact with the upper end of the cutout hole 23a.

  Reference numeral 32 denotes an ejector mechanism, which generally comprises an ejector button 33, an ejector shaft 34, an ejector lock 35, an upper ejector pipe 41, and a lower ejector pipe 42 as shown in FIG. The ejector shaft 34 passes through a hole 52a of the counter plate 52 described later and a hole 2b (see FIG. 21) of the central partition wall 2. As shown in FIG. 19, the upper ejector pipe 41 has a pair of engaging convex portions 41a on the inner periphery of the lower end. As shown in FIG. 20, the lower ejector pipe 42 has a pair of outer peripheral groove portions 42a, and each outer peripheral groove portion 42a has a guide groove 42b and three engagement concave portions 42c, 42d, and 42e. In FIG. 1, 43 is an ejector spring, 44 is an ejector spring presser, and 45 is an ejector cushion.

  Therefore, when the lower ejector pipe 42 is inserted into the lower end of the upper ejector pipe 41, the former engaging projections 41a are engaged and inserted into the latter outer peripheral groove 42a via the guide grooves 42b, and then the latter is inserted into the former. , Each engaging projection 41a is engaged with one of the three engaging recesses 42c, 42d, and 42e, and the latter is axial (vertical direction) with respect to the former. ) The position is variably fixed. That is, when the engaging convex portion 41a engages with the upper engaging concave portion 42c, the lower protruding length of the lower ejector pipe 42 is the maximum, and when engaged with the lower engaging concave portion 42e, the lower protruding length is When it is the smallest and engages with the intermediate engagement recess 42d, the downward projecting length is about the middle. As a result, even if a tip 46 (see FIG. 1) of various standard dimensions is attached to the outer periphery of the nozzle tip 24, the downward projecting length of the lower ejector pipe 42 can be adjusted accordingly. Can do. In FIG. 1, since the engaging convex portion 41a is engaged with the intermediate engaging concave portion 42d, the downward projecting length of the lower ejector pipe 42 is about the middle.

  In the above embodiment, one first engaging portion 41a of the upper ejector pipe 41 is switched and engaged with one of the plurality of second engaging portions 42c, 42d, 42e of the lower ejector pipe 42. On the contrary, one engaging portion of the lower ejector pipe 42 may be switched and engaged with any of the plurality of engaging portions of the upper ejector pipe 41, and the plurality of engaging portions is limited to three. 2 or 4 or more may be sufficient.

  Reference numeral 51 denotes a counter mechanism. As shown in FIG. 21, a drive drum 54 and three three-way counters 53 are fitted between a central partition wall 2 and a counter plate 52 (see FIG. 22). Three interlocking pinions 57 fitted into the driven drum 55, the pinion shaft 56 (inserted between the hole 2c of the central partition wall 2 and the hole 52b of the counter plate 52), and the transmission gear shaft 58 (the hole 2d of the central partition wall 2) And a single transmission gear 59 that is fitted between the holes 52c of the counter plate 52. A small-diameter pinion 59 a of the transmission gear 59 is variably set and meshed with the outer peripheral gear portion 4 a of the calibration pipe 4, and a large-diameter gear 59 b is meshed with the pinion 54 a of the drive drum 54. The first interlocking pinion 57 meshes with the partial teeth 54b of the driving drum 54 and the gear 55a of the first driven drum 55, and the second and third interlocking pinions 57 are similarly connected to the second and third interlocking pinions 57. It meshes with the partial teeth 55b of the driven drum 55 and the gear 55a. In this case, a total of four drums 54 and 55 are each provided with 10 numbers 1 to 0 on the outer circumference at equal positions in the circumferential direction, and the suction capacity value is displayed as a whole by four digits. Reference numeral 60 denotes a click spring (see FIG. 21), which is fixed to the recess 52d of the counter plate 52 by screws 61, and the click protrusion 60a is selected from ten click recesses 54c arranged equally in the circumferential direction of the drive drum 54. Thus, the driving drum 54 is positioned in the rotational direction by switching and engaging.

  Therefore, when the capacity variable setting and calibration pipe 4 is manually rotated, for example, clockwise as viewed from above, the transmission gear 59 meshing with the outer peripheral gear portion 4a of the pipe 4 rotates in the direction of arrow A in FIG. Therefore, the drive drum 54 rotates in the direction of the arrow B, and thereafter, the drive drum 55 is sequentially carried up by meshing with the partial teeth 54b and 55b and the interlocking pinions 57, and the suction capacity value is displayed in a reduced manner. If the capacity variable setting and the calibration pipe 4 are rotated counterclockwise, the suction capacity value is displayed in an increased manner.

Next, the operation of the pipette will be described.
First, when the pipette is held with one hand and the button 6 is pushed down with the thumb, the apparently integrated central shaft 7, the cylindrical plunger head 26 and the plunger 29 are opposed to the first stage spring 10 and the flange portion 7 c of the central shaft 7 is moved. The first stage stroke L1 (see FIGS. 1 and 2) is slid downward until it contacts the second stage spring retainer 27. In this state, the lower end of the tip 46 is immersed in the sample liquid.

  Here, when the pressing force is released, the central shaft 7 and the plunger 29 are returned upward by the first-stage spring 10, and the stopper step 7b of the central shaft 7 comes into contact with and returns from the flange 5a of the stroke screw 5. Returning to the state 1, a predetermined amount of the sample liquid is sucked into the chip 46.

  Next, the tip of the tip 46 is inserted into another container, and the push button 6 is pushed down again. Then, in the same manner as described above, the plunger 29 is again moved down to the position shown in FIG. 2 by the first-stage stroke L1, and the sample is discharged from the tip 46 into another container by this first-stage discharge.

  When the push button 6 is further pushed down from the position of FIG. 2, the center shaft 7 and the plunger 29 can be added to the first-stage spring 10, but also against the second-stage spring 30. The second stage stroke L2 slides (see FIGS. 2 and 3) until 27a contacts the lower end of the cutout hole 23a of the seal retainer 23. By this second stage discharge, even if the sample remains in the chip 46 when the first stage discharge is completed, it is completely discharged. Therefore, there is no error in sample volume between inhalation and discharge, and a predetermined amount of sample can be transferred accurately and reliably.

  Next, regarding the sample suction volume variable operation, as described above, when the capacity variable setting and calibration pipe 4 is rotated, for example, clockwise when viewed from above, the clutch pipe 3 and the stroke screw 5 are in the same direction. As a result, the stroke screw 5 (central shaft 7) moves downward in FIG. 1 to variably set the numerical value of the first stroke L1 (suction capacity), and the pipe 4 is reversed. When rotating counterclockwise, the numerical value of the first stage stroke L1 is variably set. When the suction capacity is variably set, the numerical values corresponding to the variable setting capacity are variably displayed by the drums 54 and 55 by simultaneously meshing the outer peripheral gear portion 4a and the pinion portion 59a (see FIG. 21) of the transmission gear 59.

  According to the above configuration, the first-stage spring 10 is arranged not between the stroke screw 5 but the upper stroke screw 5 and the push button 6. Accordingly, during the suction capacity variable setting operation, the first-stage spring 10 moves in the vertical direction with the entire length of the spring itself being constant, so that the initially-set first-stage spring 10 load remains constant during the movement. . Therefore, for example, when the suction capacity is set to be small, the first stage spring 10 is not compressed at all, so that the first stage spring 10 load does not increase and the button operation load does not fluctuate. On the other hand, in the conventional example, since the first stage spring is located below the member corresponding to the stroke screw, the first stage spring itself is compressed during the variable capacity setting operation, so that the spring load increases and the button operation load fluctuates. is there.

  Next, a method for variably setting the initial load of the first stage spring 10 will be described. In FIG. 1, the first-stage spring load variable pipe 8 is rotated clockwise relative to the push button 6. Then, the first-stage spring expansion / contraction setting plate 9 is moved downwardly in the drawing by the screwing of the inner peripheral screw 8a of the pipe 8 and the outer peripheral screw 9a of the first-stage spring expansion / contraction setting plate 9 (see FIG. 9), the first-stage spring 10 is compressed by the amount of movement, and the initial load is set large. If the first-stage spring load variable pipe 8 is rotated in the reverse direction, the initial load can be set small. Thereby, the feeling (weight) when pushing down push button 6 by changing the initial load of 1st stage spring 10 suitably can be adjusted.

Next, a method for calibrating the numerical display itself when the counter numerical value display of the counter mechanism 51 is out of order will be described.
In FIG. 1, the variable capacity setting and calibration pipe 4 is pulled upward by a dimension m against the pipe holding spring 13. As a result, the clutch engagement between the clutch pawl 4b of the variable setting pipe 4 and the engagement gear portion 3a of the clutch pipe 3 is released, but the engagement between the outer peripheral gear portion 4a of the variable setting pipe 4 and the pinion portion 59a of the transmission gear 59. Is maintained because the axial length of the gear is relatively large. Accordingly, when the variable setting pipe 4 is continuously rotated, for example, clockwise when viewed from above, the clutch pipe 3 and the stroke screw 5 do not rotate due to the release of the clutch, so the actual capacity of the cylinder chamber 21b is not changed. The drums 54 and 55 are rotated through the transmission gear 59, and the numerical display itself is calibrated to be small. Further, if the variable setting pipe 4 is rotated in the reverse direction, the numerical display itself is calibrated so as to increase. This eliminates the need for a calibration jig or the like, and allows easy calibration.

  Next, the ejecting operation of the tip 46 by the ejector mechanism 32 will be described. In order to remove the tip 46 after the sample has been ejected, the eject button 33 is pushed downward in FIG. 1 with the thumb. Then, the lower ejector pipe 42 rapidly slides downward against the ejector spring 43 via the ejector shaft 34 and the upper ejector pipe 41. Accordingly, the lower end of the lower ejector pipe 42 abuts against the tip 46 and presses the tip 46 downward so that the lower ejector pipe 42 is rapidly detached from the nozzle tip 24. Thus, the next tip can be mounted, but if the size of the tip 46 is different, the upper end position of the tip 46 when it is fitted to the nozzle tip 24 may fluctuate, and the eject operation may not be successful. is there.

  In order to cope with this, the vertical position of the lower ejector pipe 42 can be variably set. When it is desired to move the lower ejector pipe 42 further downward than the position shown in FIG. 1, the lower ejector pipe 42 is temporarily turned to release the engagement of the intermediate engagement recess 42d with the engagement protrusion 41a of the upper ejector pipe 41. (See FIGS. 19 and 20) After pulling and moving downward, the upper engaging recess 42c is engaged with the engaging protruding portion 41a to set the lower position. Is completed. Similarly, when the lower ejector pipe 42 is pushed upward and moved to engage the lower engagement recess 42e with the engagement protrusion 41a, the upper position setting is completed. As a result, it is possible to attach chips 46 of various dimensions.

  In the above embodiment, when the variable capacity setting and the suction capacity variable setting by the calibration pipe 4 are set, when the pipe 4 is rotated in any direction, the clutch pipe 3 and the stroke screw 5 are integrally rotated in the same direction. As a result, the stroke screw 5 moves up and down and the suction capacity is variably set. However, for the purpose of variably setting the suction capacity, the clutch pipe 3 is not always necessary, and the pipe 4 The structure which rotates directly with the stroke screw 5 may be sufficient.

  Next, a second embodiment of the pipette according to the present invention will be described with reference to FIGS. 24 to 32. In FIG. 24, the same parts as those in FIGS. Omitted. The second embodiment is particularly characterized in the plunger seal mechanism provided between the plunger 29 and the cylindrical cylinder 121 into which the plunger 29 is slidably fitted.

  24 and 25, the plunger seal mechanism includes an O-ring holding ring 101 fitted to the plunger 29, a seal ring 102 fitted to the plunger 29, the O-ring holding ring 101, and the seal ring. The O-ring 103 interposed between the O-rings 102, the O-ring holding ring 101 and the O-ring 103 interposed between the seal rings 102, and the O-ring holding ring 101 are pressed with a predetermined force in the axial direction. The O-ring 103 is pressed against the inclined inner surface 121a of the cylindrical cylinder member 121, and the seal ring 102 is moved radially inward with respect to the outer peripheral surface of the plunger 29 by a component force in a direction perpendicular to the axis of the predetermined force. And an O-ring pressing spring 104 to be pressed. In this case, the inclination angle α of the inclined inner surface 121a is 40 ° to 65 °, preferably 50 ° with respect to the direction perpendicular to the axis of the pipette, as will be described later.

  In the case of the second embodiment, the cylindrical seal holder 123 itself is slightly different in configuration from the cylindrical seal holder 23 of the first embodiment, and as shown in FIGS. 27A and 27B, The spring receiving portion 123a is provided with a flange portion 123b at the upper end. As shown in FIG. 24, the upper flange portion 123 b is sandwiched between the cylindrical body 1 and the upper end of the cylindrical cylinder 121, so that the cylindrical seal holder 123 is fixed to the cylindrical body 1 in the vertical direction. Is to be positioned.

As shown in FIG. 28, the O-ring holding ring 101 has an O-ring pressing portion 101a and a spring receiving portion 101b.
29A and 29B, the seal ring 102 has an annular seal portion 102a, a flange-shaped O-ring receiving portion 102b, and three inner peripheral grooves 102c provided on the inner peripheral surface of the seal portion 102a. However, the inner circumferential groove 102c is not necessarily provided, or may be provided in addition to three, one, two, or four or more. 25, the O-ring 103 (see FIG. 30A and FIG. 30B) is stored in the O-ring holding portion 101a of the O-ring holding ring 101, and the O-ring holding portion 101a and the seal ring 102 are sealed. It is stored between the parts 102a. The material of the seal ring 102 is, for example, PTFE (trade name: Teflon), which is a material having low frictional resistance and high wear resistance. Glass fiber or carbon fiber or the like is mixed into this PTFE to provide wear resistance. The material may be improved.

  As shown in FIG. 25, the O-ring pressing spring 104 is interposed between the spring receiving portion 123a of the cylindrical seal retainer 123 and the spring receiving portion 101b of the O-ring holding ring 101. The O-ring 103 is pressed against the inclined inner surface 121a of the cylindrical cylinder 121 by the axial (downward) force P (see FIGS. 31 and 32) through the seal ring 102.

  Therefore, in FIG. 31, when the O-ring 103 is pressed against the inclined inner surface 121a, two component forces of the axial (downward) force P, that is, the component force Q and the axis perpendicular to the inclined inner surface 121a. An orthogonal component R is generated, which is shown as a vector in FIG. That is, in FIG. 32, Q and R are component forces obtained by shifting the force P to the position of the force P ′ and disassembling it as a parallelogram. In this case, as an example, when the force P (P ′) is 307.6 g, the values of the component forces Q and R are 478.54 g and 366.58 g, respectively, when the angle α is 50 °.

  31 and 32, the angle of the inner surface (not shown) of the conventional cylindrical cylinder corresponding to the inclined inner surface 121a of the cylindrical cylinder 121 of the second embodiment, for example, β = 5 ° ( In other words, the spring force of the two-stage spring 30 is the same as the force P of the O-ring pressing spring 104 (307.6 g). , The decomposed forces q and r are 308.78 g and 26.91 g, respectively.

  Therefore, as is apparent from FIG. 32, when the inclination angle α = 50 ° of the inclined inner surface 121a of the cylindrical cylinder 121 in the second embodiment is adopted, the axially perpendicular component force (that is, the O-ring receiving seal) is adopted. The force for pressing the portion 102a) R is considerably larger than the corresponding component r in the direction perpendicular to the axis in the case of the conventional example (β = 5 °) (R = 366.58 g >> r = 26.91 g). It is understood that the seal portion 102a is pressed against the outer peripheral surface of the plunger 29 with a large force.

  Next, the operation of the plunger seal mechanism will be described. First, in FIG. 25, FIG. 31 and FIG. 32, when the plunger 29 moves up and down, the seal portion 102a of the seal ring 102 is caused by the axial orthogonal force R based on the axial spring force P of the O-ring pressing spring 104. It is deformed inward in the radial direction, that is, in a diameter reducing direction and is pressed against the outer peripheral surface of the plunger 29. Therefore, it can be seen that the outer peripheral surface of the plunger 29 is well sealed at the seal portion of the seal ring 102 and the portion where the O-ring 103 is pressed against the inclined inner surface 121a of the cylindrical cylinder 121. Therefore, even if the sliding portion wears due to repeated use, the airtightness is maintained satisfactorily, and the liquid below the seal portion does not leak upward and the dispensing accuracy is not lowered. Dispensing accuracy can be maintained.

  In this case, since there are a plurality of inner circumferential grooves 102c in the seal portion 102a of the seal ring 102, first, when the axial orthogonal force R increases, the sliding frictional resistance force of the plunger 29 also tends to increase. An increase in sliding frictional resistance can be suppressed by reducing the area of the contact surface by the inner circumferential groove 102c. Secondly, even if the seal portion 102a and the plunger 29 are worn by sliding friction and wear powder is generated, the wear powder is stored in the inner circumferential groove 102c so that the wear powder remains on the sliding surface. It prevents further progress of wear due to the abrasive effect of the wear powder when assumed. The wear powder stored in the inner circumferential groove 102c does not overflow when the number of strokes described later is about 600,000, and can store all of the wear powder generated during that time.

  Next, according to Table 1, the plunger 29 was slid back and forth with respect to the cylindrical cylinder 121 in each case where the inclined inner surface 121a of the cylindrical cylinder 121 of the pipette or an equivalent portion thereof formed a different angle α or β. The values of the accuracy standard (A) and the reproducibility standard (B) obtained each time the number of times (stroke number) is changed are shown.

In Table 1 above, at each angle α or β, measurement was performed separately for two cases where the pipette inhalation / discharge amount was 100 μl (0.1 CC) and 1000 μl (1 CC). The accuracy standard (A) is ± 1.0% when the setting is 100 μl, the allowable limit accuracy is ± 0.7% when the setting is 1000 μl, and the reproducibility standard (B) is < 0.5% is acceptable and <0.2% is acceptable when 1000 μl is set. In Table 1, unacceptable numbers are shown with an underline. In addition, a simple horizontal line in each column of Table 1 indicates that no measurement is performed. Here, the accuracy standard (A = AC) and the reproducibility standard (B = CV) are respectively given by the following equations.

Here, “x bar” is an average value (μl) of actually measured data values “x” (μl), and “set value” is a set value (μl) preset by a pipette counter. “SD” is a standard deviation and is given by the following equation.

Here, n is the number of measurements.
According to Table 1 above, in the case of the conventional example (β = 5 °), when the number of strokes is 100,000 times and 200,000 times, the seal portion 102a of the seal ring 102 lacks the sealing force, resulting in the dispensing liquid. This results in a failure of accuracy or / and reproducibility. Further, when α = 30 °, the same failure occurs at 50,000 times and 80,000 times. However, when α = 40 ° in the second embodiment, both accuracy and reproducibility are acceptable at 600,000 times. Similarly, when α = 50 °, 50,000 times, 100, 000 times and 600,000 times are similarly acceptable. Similarly, when α = 65 °, the test passes similarly at 600,000 times. When α is larger than 65 °, most of the axial force P from the O-ring pressing spring 104 acting on the O-ring 103 is converted into the axial orthogonal force R (see FIGS. 31 and 32), and the axis Since the orthogonal direction force R becomes large, the pressing force for sliding the plunger 29 becomes larger than necessary and the operation becomes difficult. Therefore, it is difficult to employ, and experimental data when α> 65 ° is not collected. If the seal part can guarantee the accuracy up to 600,000 times, it is sufficient as a practical life as a maintenance-free product.

It is an expansion longitudinal cross-sectional view of the upper half part of one Embodiment of the pipette which becomes this invention. It is an expansion longitudinal cross-sectional view of the lower half part of one Embodiment of the pipette which becomes this invention. FIG. 2 is a longitudinal sectional view of an upper half portion of the pipette of FIG. It is a longitudinal cross-sectional view of the upper half part of the pipette of FIG. It is a perspective view of a cylindrical body. It is a longitudinal section of a cylindrical body. It is a perspective view of a center partition. It is a top view of a center partition. It is a perspective view of a clutch pipe. It is a top view of a clutch pipe. It is a perspective view of a capacity variable setting and calibration pipe. It is a longitudinal section of a capacity variable setting and calibration pipe. It is a bottom view of a capacity variable setting and calibration pipe. It is a perspective view of a stroke screw. It is a longitudinal section of a stroke screw. It is a perspective view of a push button. It is a bottom view of a push button. It is a side view of a center shaft. It is a bottom view of a center shaft. It is a perspective view of a 1st stage spring load variable pipe. It is a perspective view of a 1 step | paragraph spring expansion-contraction setting plate. It is a top view of a 1 step | paragraph spring expansion-contraction setting plate. It is a longitudinal cross-sectional view of a cylindrical cylinder. It is a perspective view of a cylindrical seal presser. It is a longitudinal section of a cylindrical seal presser. It is a perspective view of a nozzle tip. It is a longitudinal cross-sectional view of a nozzle tip. It is a perspective view of a plunger head. It is a longitudinal cross-sectional view of a plunger head. It is a top view of a two-stage spring presser. It is a side view of a plunger. It is a perspective view of an upper ejector pipe. It is a longitudinal section of an upper ejector pipe. It is a perspective view of a lower ejector pipe. It is a side view of a lower ejector pipe. It is a longitudinal cross-sectional view of a lower ejector pipe. It is a disassembled perspective view of a counter mechanism. It is a perspective view of a counter plate. It is a bottom view of a counter plate. It is a partial expanded sectional view of the attachment part of a nozzle tip. It is an expansion longitudinal cross-sectional view of the upper half part of 2nd Embodiment of the pipette which becomes this invention. FIG. 25 is an enlarged longitudinal sectional view of a main part of the pipette in FIG. 24. FIG. 25 is a longitudinal sectional view of the cylindrical cylinder of the pipette of FIG. 24. FIG. 25 is a perspective view of a cylindrical seal presser of the pipette of FIG. 24. It is a longitudinal section of the cylindrical seal presser. It is a front view of the O-ring holding ring of the pipette of FIG. It is a longitudinal cross-sectional view of the same O-ring holding ring. It is a front view of the O-ring receiving seal ring of the pipette of FIG. It is a longitudinal cross-sectional view of the same O-ring receiving seal ring. FIG. 25 is a front view of an O-ring of the pipette of FIG. 24. It is a longitudinal section of the O-ring. It is a figure which shows the force action relationship of each part of FIG. It is a figure which shows the vector of the same force.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylindrical body 2 Central partition wall 3 Clutch pipe 3a Engagement gear part 3b Axial guide protrusion 4 Capacitance variable setting and calibration pipe 4a Outer periphery gear part 4b Clutch claw 5 Stroke screw 5c Outer periphery screw 5d Axial guide recess 6 Push button 7 Central shaft 7a Large-diameter portion 7b Stopper step portion 7c Gutter portion 8 First step spring load variable pipe 8a Inner peripheral screw 9 First step spring expansion / contraction setting plate 9a Outer peripheral screw portion 10 First step spring 11 Button cover 13 Pipe holding spring 21, 121 Cylindrical cylinder 21b Cylinder chamber 21c Nozzle part 23, 123 Cylindrical seal retainer 24 Nozzle tip 24a Concavity and convexity 24b Insert molding part 25 Filter case 26 Plunger head 27 Two-stage spring retainer 27a Ear part 28 Plunger head spring 29 Plunger 30 Two-stage spring 32 Eze 33 Ejector button 34 Ejector shaft 36 Rubber or elastomer stretchable layer 41 Upper ejector pipe 41a Engaging protrusions 42c, 42d, 42e Engaging recess 42 Lower ejector pipe 46 Tip 51 Counter mechanism 52 Counter plate 54 Driving drum 55 Driven drum 57 interlocking pinion 59 transmission gear 59a pinion 60 click spring 101 O-ring holding ring 101a O-ring holding part 102 seal ring 102a seal part 102b O-ring receiving part 102c inner peripheral groove 104 O-ring pressing spring 121a inclined inner surface

Claims (13)

In a pipette,
A cylindrical body 1 having a first threaded portion 1b;
A stroke screw 5 having a second screw portion 5c screwed into the first screw portion 1b and disposed in the body 1,
A variable capacity setting member 4 disposed so as to be integrally rotatable with the stroke screw 5 and slidable in the axial direction;
A central shaft 7 connected to the plunger 29 in the cylindrical body 1 and disposed so as to be able to be pushed down;
A first-stage spring 10 interposed between the upper portion of the central shaft 7 and the stroke screw 5 to urge the central shaft 7 upward and to urge the predetermined portion 7b against the stroke screw 5; , And
By appropriately rotating the capacity variable setting member 4, the stroke screw 5 is integrally rotated with respect to the body 1, and the stroke screw 5 and the central shaft 7 are apparently integrally slid by a predetermined amount in the axial direction. A pipette characterized by variably setting the suction volume. In a pipette,
A substantially cylindrical body 1 having a first threaded portion 1b;
A stroke screw 5 having a second screw portion 5c screwed into the first screw portion 1b and disposed in the body 1,
A clutch member 3 having a first engagement portion 3a and arranged so as to be integrally rotatable with respect to the stroke screw 5 and axially slidable;
A variable capacity setting member 4 having a second engagement portion 4b and arranged to be integrally rotatable when the first and second engagement portions 3a, 4b are engaged with the clutch member 3,
A central shaft 7 connected to the plunger 29 in the cylindrical body 1 and disposed so as to be able to be pushed down;
A first-stage spring 10 interposed between the upper portion of the central shaft 7 and the stroke screw 5 to urge the central shaft 7 upward and to urge the predetermined portion 7b against the stroke screw 5; , And
By appropriately rotating the capacity variable setting member 4, the stroke screw 5 is integrally rotated with respect to the body 1, and the stroke screw 5 and the central shaft are apparently integrally slid in the axial direction by a predetermined amount. A pipette characterized by variably setting the suction volume. In a pipette,
A substantially cylindrical body 1 having a first threaded portion 1b;
A stroke screw 5 having a second screw portion 5c screwed into the first screw portion 1b and disposed in the body 1,
A central shaft 7 connected to the plunger 29 in the cylindrical body 1 and disposed so as to be able to be pushed down;
A first-stage spring load variable member 8 having a third threaded portion 8a and provided on the upper portion of the central shaft 7 so as to be relatively rotatable;
A first-stage spring expansion / contraction setting member 9 that has a fourth screw portion 9a that is screwed into the third screw portion 8a, and that is provided on the upper portion of the central shaft 7 so as not to be relatively rotatable and axially slidable;
A first-stage spring 10 interposed between the upper portion of the central shaft 7 and the stroke screw 5 to urge the central shaft 7 upward and to urge the predetermined portion 7b against the stroke screw 5; , And
By appropriately rotating the first-stage spring load variable member 8, the first-stage spring expansion / contraction setting member 9 is slid in the axial direction with respect to the body 1 so that the total length of the first-stage spring 10 can be varied. A pipette characterized by its expansion / contraction setting. In a pipette having a resin cylindrical housing 1 or 21,
A pipette in which a ceramic nozzle tip 24 is integrally insert-molded at the tip of the cylindrical housing 1 or 21. The pipette of claim 4.
The pipette characterized in that the ceramic nozzle tip 24 is insert-molded with a stretchable layer 36 of rubber or elastomer at a predetermined location 24c before insert molding into the cylindrical housing 1 or 21. The pipette according to claim 4 or 5,
The ceramic nozzle tip 24 has a concavo-convex portion 24a formed on the outer periphery thereof. In a pipette with a cylindrical body 1
A pipette wherein the material of the cylindrical body 1 is a fine foam molding material. The pipette of claim 7,
The pipette characterized in that the fine foam molding material is polyphenylsulfone. In a pipette with a tip ejector mechanism,
The ejector mechanism 32 includes at least an eject button 33, an upper ejector pipe 41, and a lower ejector pipe 42 that presses the tip 46,
The first engagement portion 41a provided on one of the upper ejector pipe 41 and the lower ejector pipe 42 is switched to one of a plurality of second engagement portions 42c, 42d, and 42e provided on the other. The tip position of the lower ejector pipe 42 can be varied. In a pipette,
Cylindrical body 1 and
A stroke screw 5 disposed in the body 1 for variably setting a suction capacity;
A clutch member 3 having a first engagement portion 3a and arranged so as to be integrally rotatable with respect to the stroke screw 5 and axially slidable;
A calibration member having a second engagement portion 4b, which is axially slidable relative to the clutch member 3 and is integrally rotatable only when the first and second engagement portions 3a and 4b are engaged. 4 and
A central shaft 7 connected to the plunger 29 in the cylindrical body 1 and disposed so as to be able to be pushed down;
An inhalation volume display counter mechanism 51 that can be interlocked with the calibration member 4;
When the calibration member 4 is slid in the axial direction, the stroke screw 5 is rotated by rotating the calibration member 4 appropriately while the first and second engaging portions 3a and 4b are disengaged. The pipette is characterized in that only the counter mechanism 51 is operated to calibrate the numerical value of the suction volume. In a pipette,
In a pipette in which the central shaft 7 disposed in the cylindrical body 1 so as to be movable up and down integrally with the plunger 29 is pushed down against at least the first-stage spring 10, the plunger 29 and the plunger 29 are slidable. A plunger seal mechanism of a pipette provided between the cylindrical cylinder member 121 and the plunger seal mechanism,
An O-ring holding ring 101 fitted to the plunger 29;
A seal ring 102 fitted to the plunger 29;
An O-ring 103 interposed between the O-ring holding ring 101 and the seal ring 102;
The O-ring holding ring 101 is pressed in the axial direction with a predetermined force to press the O-ring 103 against the inclined inner surface 121a of the cylindrical cylinder member 121. An O-ring pressing spring 104 that presses the seal ring 102 radially inward against the outer peripheral surface of the plunger 29;
An inclination angle α of the inclined inner surface 121a is 40 ° to 65 ° with respect to the direction perpendicular to the axis of the pipette. The pipette plunger seal mechanism of claim 11,
The pipette plunger seal mechanism is characterized in that the inclination angle α of the inclined inner surface 121a is 50 ° with respect to the direction perpendicular to the axis of the pipette. The pipette plunger seal mechanism according to claim 11 or 12,
The pipe ring plunger seal mechanism, wherein the seal ring 102 has one or a plurality of circumferential grooves 102 c on the inner peripheral surface of a seal portion 102 a fitted to the outer peripheral surface of the plunger 29.

Images