JP2001153065A - Micro pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a micro pump capable of preventing worn dust from mixing into a cylinder by collecting and storing the worn dust and also increasing the life of a seal part by minimizing the produced worn dust. SOLUTION: This micro pump comprises a cylinder 11, a plunger 12 reciprocating in the cylinder 11, and a seal part 14 sealing the inside of the cylinder 11, allowing the outer peripheral surface 13 of the plunger 12 to be slid thereon, and having a dust collecting mechanism 20 collecting and storing the worn dust produced by the sliding. The seal part 14 can be formed of a material containing a thermoplastic resin and a modifier for reducing the coefficient of friction or a material containing a thermoplastic resin of 5 to 30% or less in coefficient of water absorption. The average surface roughness of the sliding surface 19 on the seal part 14 can be set to 0.1 to 5 μm or less, and the average surface roughness of the outer peripheral surface part 13 can be set to 0.01 to 0.1 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micropump for sucking and discharging a sample in an amount corresponding to the amount of movement of a plunger.

[0002]

2. Description of the Related Art Conventionally, for example, a micropump employed in a general metering pump device or the like includes a cylinder and a plunger reciprocating in the cylinder, and the plunger in the cylinder is retracted. Then, there is a type in which an amount of liquid corresponding to the retreat amount (stroke) is sucked in and the plunger is advanced to discharge an amount of liquid corresponding to the advance stroke.

In order to prevent the liquid in the cylinder pressurized by the movement of the plunger from leaking to the outside through the outer peripheral surface of the plunger, such a micropump is provided with the plunger inlet of the cylinder and the plunger. And a seal portion that seals the inside of the cylinder and allows the outer peripheral portion of the plunger to slide. In this micropump, the suction amount and the discharge amount are precisely determined by the retreat stroke and the forward stroke of the plunger.

Since the conventional micropump has a structure in which the plunger slides with respect to the seal portion, friction or wear generated during the sliding generates wear dust (wear debris). However, there is a problem that the sealing performance is deteriorated by mixing into the liquid in the cylinder or damaging the sealing surface.

Therefore, in recent years, in order to prevent the generation of the abrasion dust, for example, the seal portion is made of a material having a small friction coefficient such as polyethylene or fluororesin, or a material obtained by mixing fluorocarbon with carbon. And a method of improving wear resistance. However, even if the method for preventing the generation of wear dust described above is performed,
The reality is that wear dust cannot be completely eliminated.

[0006] A micropump provided with a mechanism for washing and removing generated abrasion dust with a liquid or gas as necessary is also introduced.

[0007]

In a conventional micropump provided with a mechanism for cleaning and removing generated abrasion dust, the abrasion dust is flushed with a liquid or a gas while the machine is stopped, or the cleaning is performed. It is necessary to disassemble necessary parts to remove wear dust. For this reason, there is a concern that the operation efficiency is reduced, such as a troublesome operation and a suspension of the liquid suction and discharge operations by the micropump.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem. It is possible to collect and store generated abrasion dust, and the abrasion dust is mixed into a cylinder. It is an object of the present invention to provide a micropump capable of preventing the above.

It is another object of the present invention to provide a micropump capable of minimizing generated wear dust and improving the life of the seal portion.

[0010]

In order to achieve this object, the present invention provides a cylinder, a plunger which reciprocates in the cylinder, a seal in the cylinder, and an outer peripheral portion of the plunger is slidable. And a seal portion, wherein the seal portion is provided with a dust collecting mechanism for collecting and storing wear dust generated by sliding of the plunger.

In the micropump having this configuration, the generated dust is collected and stored by the dust collecting mechanism, so that it is possible to prevent the dust from entering the cylinder.

The dust collecting mechanism may have a structure including a groove formed on a sliding surface of the seal portion with the plunger.

The groove may be formed in an annular shape along the sliding surface of the seal. The number of the annular groove portions may be one or plural.

The seal portion may be made of a material containing a thermoplastic resin and a modifier for reducing a coefficient of friction.

By forming the seal portion from such a material, the coefficient of friction of the seal portion is reduced, so that the generation of wear dust due to friction and wear can be suppressed. For this reason, the sealability is improved, the variation in durability is reduced, and the life of the seal portion can be improved.

Examples of such modifiers include liquid crystal polymers such as carbon, silicon, and econol, ceramics, polyimides, glass fibers, and other low polymer polymers.

The seal portion has a water absorption of 5% or more and 30% or more.
% Of a thermoplastic resin.

When the seal portion is made of such a material, the moisturizing water is always present in an optimal amount on the sliding surface of the seal portion, so that wear is reduced and
The coefficient of friction can be reduced. Therefore, generation of wear dust due to friction and wear can be further suppressed.

The seal portion has a surface average roughness (Ra) of at least 0.1 on a sliding surface with the plunger.
It can be set to be not less than μm and not more than 5 μm.

With this configuration, the coefficient of friction of the seal portion can be reduced, and the generation of wear dust due to friction and wear can be further suppressed.

The average surface roughness (Ra) of the outer peripheral surface of the plunger is not less than 0.01 μm and not more than 0.1 μm.
You can set:

With this configuration, the friction coefficient of the outer peripheral surface of the plunger, that is, the portion in contact (sliding) with the seal portion can be reduced, and the generation of wear dust due to friction and wear can be further suppressed. can do.

[0023]

Next, a micropump according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a micropump device according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the vicinity of a seal portion of the micropump device shown in FIG.

As shown in FIGS. 1 and 2, the micropump device 1 according to the present embodiment is provided with a pump unit 2, a positioning drive unit 3, and a motor unit 4.

The pump section 2 includes a cylinder 11, a plunger 12 reciprocating in the cylinder 11, a seal section 14 in which the outer periphery 13 of the plunger 12 is slidable while sealing the inside of the cylinder 11, and a A suction port 15 and a discharge port 16 communicating with the distal end are provided. A suction port (not shown) is connected to the suction port 15, and a discharge port (not shown) is connected to the discharge port 16.

In the present embodiment, the plunger 12
Has an average surface roughness (Ra) of 0.01 μm
As described above, the thickness is set to 0.1 μm or less. By setting the surface roughness in this manner, the coefficient of friction of the outer peripheral portion 13 of the plunger 12 can be reduced, and generation of wear dust due to friction and wear can be suppressed.

The seal portion 14 is disposed between the end face 18 of the plunger insertion opening (the right end face in FIG. 1 of the housing 17) of the housing 17 defining the cylinder 11 and the outer peripheral portion (outer peripheral surface) 13 of the plunger 12. ing. The seal portion 14 includes a sliding surface 19 that slides on the outer peripheral portion 13 of the plunger 12, and a dust collecting mechanism 20 that collects and stores wear dust generated by sliding of the plunger 12.
An O-ring 23 is disposed on the tip side of the plunger 12 of the dust collecting mechanism 20 (left side in FIGS. 1 and 2), and is slidable with respect to the outer peripheral portion 13 of the plunger 12.

The dust collecting mechanism 20 is, as shown in FIG.
It is provided with two grooves 21 and 22 formed annularly along the sliding surface 19. This dust collecting mechanism 20
For example, it is composed of a material containing a thermoplastic resin and a modifier capable of reducing the coefficient of friction. In the present embodiment, carbon is used as the modifier, but liquid crystal polymers such as silicon and econol, ceramics, polyimides, glass fibers, and other low-polymer polymers can also be used. This modifier is preferably added at a ratio of about 0.1% to 30% by weight based on the thermoplastic resin. When the dust collecting mechanism 20 is made of such a material, the coefficient of friction of the seal portion 14 is reduced, so that generation of wear dust due to friction and wear can be suppressed. For this reason, the sealability is improved, the variation in durability is reduced, and the life of the seal portion can be improved.

Further, in the present embodiment, a resin having a water absorption of 5% or more and 30% or less, for example, polyamide is used as the thermoplastic resin. By selecting a thermoplastic resin having such a water absorption, the sealing portion 14
Since the moisturizing water is always present in an optimal amount on the sliding surface 19, the wear can be reduced and the friction coefficient can be reduced. Therefore, generation of wear dust due to friction and wear can be further suppressed.

In the present embodiment, the average surface roughness (Ra) of the sliding surface 19 of the dust collecting mechanism 20 is set to 0.1 μm or more and 5 μm or less. By setting the surface roughness in this manner, the coefficient of friction of the seal portion 14 can be reduced, and the generation of wear dust due to friction and wear can be further suppressed.

When the plunger 12 moves rightward in FIG. 1, the volume of the space in the cylinder 11 is enlarged, and a sample (for example, a liquid) is sucked into the cylinder 11 from the suction port 15. You. Also, plunger 1
When 2 moves to the left as shown in FIG. 1, the space volume in the cylinder 11 is reduced, and the sample in the cylinder 11 is discharged from the discharge port 16. The inhalation amount and discharge amount of this sample are
It is determined by the moving amount (moving stroke) of the plunger 12.

The positioning drive unit 3 includes a shutter 31 provided on the base end side of the plunger 12 (the right side shown in FIG. 1),
And a sensor 32 for detecting the position of the shutter 31. This sensor 32 will be described later in detail,
When the plunger 12 moves to a preset origin position, the shutter 31 is detected and an electric signal (detection signal) is output. Reference numeral 33 denotes a bearing.

The motor unit 4 includes a rotor 41 having an internally threaded portion, a feed screw 42 having a threaded portion for screwing the rotor 41, a motor coil 43 for rotating the rotor 41, and both ends of the rotor 41. And a bearing 44 for supporting. The feed screw 4
2 is connected to the plunger 12.

Next, a specific operation of the micropump device 1 according to the present embodiment will be described.

First, when a desired sample (for example, a liquid) is sucked into the cylinder 11, the motor coil 43 of the motor section 4 is excited in the reverse direction, and the rotor 41 of the motor section 4 is excited.
Rotates to move the feed screw 42 rightward as shown in FIG. By this operation, the plunger 12 connected to the feed screw 42 moves rightward, the space volume in the cylinder 11 is expanded, and the sample is sucked into the cylinder 11 from the suction port 15. At this time, since the plunger 12 slides with respect to the seal portion 14, friction occurs between the outer peripheral portion 13 of the plunger 12 and the sliding surface 19 of the seal portion 14.

On the other hand, when the sample sucked into the cylinder 11 is to be discharged, the motor coil 43 of the motor unit 4 is excited in the forward direction, and the rotor 41 of the motor unit 4 is rotated in the opposite direction. The feed screw 42 is moved to the left as shown in FIG. By this operation, the plunger 12 connected to the feed screw 42 moves leftward, and the cylinder 11
The volume of the space inside is reduced, and the sample in the cylinder 11 is discharged from the discharge port 16. When the plunger 12 reaches the discharge end position, the sensor 32 detects the shutter 31 and outputs an electric signal. With this electric signal, the plunger 1
2 is accurately positioned at the origin position, and a precise amount of sample is discharged. Also in this operation, since the plunger 12 slides with respect to the seal portion 14, friction occurs between the outer peripheral portion 13 of the plunger 12 and the sliding surface 19 of the seal portion 14.

The seal portion 14 is gradually worn due to the friction generated when the sample is sucked and discharged.
Since the seal portion 14 (the dust collecting mechanism 20) is made of a material having the above-described low coefficient of friction and an optimum water absorption, the amount of abrasion dust generated by the abrasion can be reduced. Furthermore, the sealability is improved, the variation in durability is reduced, and the life of the seal portion can be improved. Further, the abrasion dust that has been generated still remains as the dust collection mechanism 20 moves with the movement of the plunger 12.
The dust is collected in the grooves 21 and 22, and is stored here. Therefore, it is possible to prevent wear dust from being mixed into the cylinder 11.

When a durability test on suction and discharge of a reagent was performed using the micropump device 1 according to the present embodiment, 500
It showed durability of more than 10,000 times.

Note that the seal portion of the micropump according to the present invention is not limited to the shape described in the above-described embodiment, but may be, for example, a plunger sliding member having a shape as shown in FIGS. Other shapes may be used as long as a dust collecting mechanism for collecting and storing wear dust generated by the dust collecting mechanism is provided.

The seal portion 14A shown in FIG. 3A has an annular shape formed along the sliding surface 19 with the plunger 12.
A dust collecting mechanism 20A having a plurality of grooves 51;
And an O-ring 23 disposed on the left side of A (the distal end side of the plunger 12).

The seal portion 14B shown in FIG.
The dust collecting mechanism 20A shown in (1) and an O-ring 23 arranged on the right side of the dust collecting mechanism 20A are provided.

The seal portion 14C shown in FIG.
The dust collecting mechanism 20A shown in (1) and O-rings 23 arranged on both sides of the dust collecting mechanism 20A are provided.

The seal portion 14D shown in FIG. 3D has an inner diameter substantially equal to the diameter of the plunger 12,
An annular member 61 slidable on the outer peripheral portion 13 of the
And a dust collecting mechanism 20B having a structure in which four annular members 61 and three annular members 62 are alternately combined such that an annular member 62 having an inner diameter larger than 1 is formed into the annular members 61 at both ends.
And an O-ring 2 disposed on the left side of the dust collecting mechanism 20B.
3 is provided. This dust collecting mechanism 20B
Has irregularities formed on the surface facing the plunger 12 due to the difference between the inner diameters of the annular members 61 and 62. As a result, a groove 51 substantially similar to that shown in FIG. 3A is formed.

The seal portion 14E shown in FIG.
The dust collecting mechanism 20B shown in (4) and an O-ring 23 arranged on the right side of the dust collecting mechanism 20B are provided.

The seal portion 14F shown in FIG.
The dust collecting mechanism 20B shown in (4) and O-rings 23 arranged on both sides of the dust collecting mechanism 20B are provided.

The seal portion 14G shown in FIG.
The OC and the O-ring 23 are integrally formed. Specifically, the dust collecting mechanism 20 </ b> C includes three grooves 51 formed in an annular shape along the sliding surface 19 with the plunger 12, and includes an O-ring housing 70 that houses the O-ring 23. .

The seal portions 14A to 14G shown in FIGS. 3 and 4 have the same operation and effects as the seal portion 14 described in the above embodiment.

3 (1) to 3 (3) and FIG.
The case where three grooves are formed has been described. However, the present invention is not limited to this, and the number and positions of the grooves can be arbitrarily determined as long as abrasion dust can be collected and stored.

The sliding surfaces and grooves of the dust collecting mechanism have the following shapes.
For example, various shapes can be taken as shown in FIGS.

More specifically, the dust collection mechanism 2 shown in FIG.
OD is formed in a ring shape along the sliding surface 19 with the plunger 12 and has a plurality of grooves 7 having a triangular cross section.
1 is formed continuously.

The dust collecting mechanism 20E shown in FIG. 5 (2) has a groove 71 formed annularly along the sliding surface 19, and a substantially circular cross-section formed adjacently and annularly along the sliding surface 19. And a trapezoidal groove 72.

The dust collecting mechanism 20F shown in FIG. 5 (3) has a groove 71 formed at a substantially central portion thereof.
The groove 73 having a substantially trapezoidal cross section is formed in an annular shape along the sliding surface 19.

The dust collecting mechanism 20G shown in FIG. 5 (4) has a groove 74 having a substantially radial cross section formed annularly along the sliding surface 19.

In the dust collecting mechanism 20H shown in FIG. 5 (5), the sliding surface 19 of the dust collecting mechanism 20A is curved into a substantially semicircular cross section.

The shape of the groove is not limited to the above-described annular shape, and any shape such as a spiral, an ellipse, an ellipse, and a rectangle is particularly limited as long as it can collect and store wear dust. is not.

In FIGS. 3 (4) to 3 (6), the grooves are formed by combining annular members 61 and 62 having different inner diameters. However, the number of annular members 61 and 62 may be determined arbitrarily. Can be.

Further, the shape of the annular member forming the dust collecting mechanism can take various shapes, for example, as shown in FIGS. 6 (1) to 6 (5).

Specifically, the dust collecting mechanism 2 shown in FIG.
0I is a combination of a plurality of annular members 75 each having a substantially triangular cross section at the tip contacting the outer peripheral portion 13 of the plunger 12,
By disposing annular members 76 and 77 obtained by processing the annular member 75 to a half thickness at both ends, FIG.
The dust collecting mechanism 20D shown in FIG.

The dust collecting mechanism 20J shown in FIG. 6 (2) includes an annular member 78 having a substantially trapezoidal cross section at the end contacting the outer peripheral portion 13 of the plunger 12, and the above-described annular members 62 and 76.
5 (2) by further arranging an annular member 79 on the opposite side of the annular member 78 of the annular member 62.
The grooves 71 and 7 are substantially the same as the dust collecting mechanism 20E shown in FIG.
2 is formed.

The dust collecting mechanism 20K shown in FIG. 6 (3) has two annular members 75 arranged next to each other, annular members 62 arranged on both sides thereof, and annular members 61 arranged on both sides thereof.
Are provided, thereby forming grooves 71 and 73 substantially similar to those of the dust collecting mechanism 20F shown in FIG. 5 (3).

In the dust collecting mechanism 20L shown in FIG. 6 (4), both sides of the annular member 61 are sandwiched between annular members 80 each having a substantially semicircular cross-sectional shape at the tip contacting the outer peripheral portion 13 of the plunger 12. By providing the annular members 61 on both sides, grooves 71 and 74 substantially similar to the dust collecting mechanism 20G shown in FIG. 5D are formed.

The dust collecting mechanism 20M shown in FIG. 6 (5) alternately arranges annular members 81 and annular members 62 whose tip portions in contact with the outer peripheral portion 13 of the plunger 12 project in a semicircular shape. Thus, a configuration is provided in which a groove 51 substantially similar to the dust collecting mechanism 20H shown in FIG. 5 (5) is formed.

[0064]

As described above, the micropump according to the present invention has a dust collecting mechanism that collects and stores wear dust generated by sliding of the plunger. The generated wear dust is collected and stored by the dust collection mechanism. For this reason, it is possible to prevent wear dust from entering the cylinder, and it is possible to improve the reliability of the micropump.

Further, the seal portion is made of a material containing a thermoplastic resin and a modifier for reducing a friction coefficient, or made of a material containing a thermoplastic resin having a water absorption of 5% or more and 30% or less. By reducing the surface average roughness (Ra) of at least the sliding surface with the plunger to 0.1 μm or more and 5 μm or less, or a combination thereof, the friction coefficient of the seal portion can be reduced. it can. For this reason, generation | occurrence | production of the said abrasion dust can be suppressed and the durability of a seal part can also be improved.

Further, by setting the average surface roughness (Ra) of the outer peripheral surface of the plunger to 0.01 μm or more and 0.1 μm or less, the friction coefficient between the seal portion and the plunger can be reduced. Therefore, the generation of the wear dust can be suppressed, and the durability of the seal portion can be further improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a micropump device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the vicinity of a seal portion of the micropump device shown in FIG.

FIG. 3 is a sectional view showing an example of a seal portion of the micropump according to the present invention.

FIG. 4 is a sectional view showing an example of a seal portion of the micropump according to the present invention.

FIG. 5 is a cross-sectional view illustrating an example of a dust collecting mechanism of a seal portion of the micropump according to the present invention.

FIG. 6 is a sectional view showing an example of a dust collecting mechanism of a seal portion of the micro pump according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Micropump device 2 Seal part 3 Positioning drive part 4 Motor part 11 Cylinder 12 Plunger 13 Outer peripheral part 14, 14A-14F Seal part 19 Sliding surface 20, 20A-20M Dust collection mechanism 21, 22, 51, 71, 72, 73 , 74 Grooves 61, 62, 75, 76, 77, 78, 79, 80, 8
1 annular member 23 O-ring

Claims (7)

[Claims] 1. A micropump comprising: a cylinder; a plunger that reciprocates in the cylinder; and a seal portion that seals the inside of the cylinder and slidably moves an outer peripheral portion of the plunger. A micropump including a dust collecting mechanism for collecting and storing wear dust generated by sliding of the plunger. 2. The micropump according to claim 1, wherein the dust collecting mechanism includes a groove formed on a sliding surface of the seal with the plunger. 3. The micropump according to claim 2, wherein the groove is formed in an annular shape along a sliding surface of the seal. 4. The micropump according to claim 1, wherein the seal portion is made of a material containing a thermoplastic resin and a modifier that reduces a coefficient of friction. . 5. The seal portion has a water absorption of 5% or more,
The micropump according to any one of claims 1 to 4, wherein the micropump is made of a material containing 0% or less of a thermoplastic resin. 6. The seal portion has a surface average roughness (Ra) of at least 0.1 μm on a sliding surface with the plunger.
The micropump according to any one of claims 1 to 5, wherein the micropump is not less than 5 µm. 7. The micropump according to claim 1, wherein the plunger has an average surface roughness (Ra) of an outer peripheral surface of 0.01 μm or more and 0.1 μm or less.