JP2691703B2 - Bellows metering pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bellows type metering pump suitable for transferring a fluid, such as a chemical solution or pure water, which is required to be metered.

[0002]

2. Description of the Related Art As a bellows type metering pump of this kind,
Conventionally, the one disclosed in Japanese Utility Model Publication No. 61-35750 is known. FIG. 4 shows a structure of a main part of the conventional bellows type metering pump disclosed in the above publication, in which a pump body 32 having a suction hole 30 and a discharge hole 31 for a fluid to be transferred has a cylindrical shape. Forming a protrusion 33,
On the central axis of the cylindrical protrusion 33, a flow hole 34 having one end communicating with the suction hole 30 and the other end opening at the tip end surface of the cylindrical protrusion 33 is formed. Is a base end of the cylindrical protrusion 33 at an inner end position of an annular gap 36 between an inner circumference of a bellows 35 disposed on an outer circumference of the cylindrical protrusion 33 and an outer peripheral surface of the cylindrical protrusion 33. An opening is connected to an annular groove 37 formed on one side surface of the pump body 32 so as to surround the peripheral portion.

Further, one end of the bellows 35 abuts on the center of one side surface of the pump body 32 and is fixed by a fixing plate 38, and the other end of the bellows 35 is closed by a closing plate 40 via a seal plate 39. At the same time, it is held by the closing plate 40 and the mounting plate 41.

According to the conventional bellows type metering pump having the above-mentioned structure, the reciprocating drive device causes the suction stroke to expand the bellows 35 to open the flow hole 34 and to make the inside of the bellows 35 negative. The fluid to be transferred is sucked into the annular gap 36 through the path of the suction hole 30 and the flow hole 34.
Further, the inside of the bellows 35 is pressurized by the discharge process of contracting the bellows 35, and the fluid to be transferred sucked into the annular gap 36 is discharged through the path of the annular groove 37 and the discharge hole 31. That is, the bellows 35 is driven by the reciprocating drive device.
It is said that the fluid to be transferred is intermittently discharged by expanding and contracting the ink, and the discharge amount is determined by the discharge stroke (discharge stroke), so that quantitative transfer can be expected.

However, the annular gap 36 and the annular groove 37
In the fluid inside, a force that flows toward the discharge hole 31 by inertia acts even after the end of the discharge stroke. In addition, at the end position of the discharge step, the seal plate 39 abuts on one end face of the bellows 35 and the tip end face of the cylindrical projection 33 with a relatively large area, respectively, to close the annular gap 36 and the flow hole 34. Therefore, the contact pressure is low and high sealing performance cannot be expected. Therefore, after the end of the discharge stroke, the fluid to be transferred in the annular gap 36 and the annular groove 37 is discharged from the discharge hole 3.
1 and flows out toward the annular gap 36
Even if the inside of the inner space is made negative pressure, the surface pressure of the contact portion cannot be increased and the sealing cannot be performed reliably by the negative pressure. 34
The fluid to be transferred continues to flow into the annular gap 36, and the flow out of the discharge hole 31 is continued even after the end of the discharge stroke, thereby preventing the fixed amount transfer.

On the other hand, when the operation of the bellows type metering pump is stopped for a relatively long time for maintenance or the like, the discharge connected to the discharge hole 31 is provided in order to prevent outflow and backflow of the transferred fluid due to the above reason. It is necessary to provide an outflow prevention valve or a backflow prevention valve in the pipe, and there is also a drawback that the structure of the attached piping system becomes complicated accordingly.

[0007]

That is, since the conventional bellows type metering pump has a low sealing property at the end position of the discharge process, the transferred fluid continues to flow out even after the end of the discharge stroke. However, it has a drawback that the fixed-quantity transfer is disturbed and a drawback that the next time the fixed-quantity transfer is hindered by the backflow of the liquid in the pipe. For this reason, it is necessary to interpose an outflow prevention valve or a backflow prevention valve in the discharge pipe, which complicates the structure of the attached piping system. Therefore, the present invention enhances the sealing property on the discharge side at the discharge process end position,
It is possible to reliably prevent the transferred fluid from flowing out after the end of the discharge stroke, to accurately perform a fixed amount transfer with the discharge amount determined by the discharge stroke, and to eliminate the need for an outflow prevention valve or check valve. In addition, it is an object of the present invention to provide a bellows type metering pump that can simplify the structure of the attached piping system.

[0008]

In order to achieve the above object, a bellows type metering pump according to the invention of claim 1 has a columnar protrusion, and the columnar protrusion has an opening at the base end thereof. And a passage for communicating with the suction hole is formed from the opening of the suction hole to the tip of the columnar projection, and the passage is opened at the tip of the columnar projection. The pump body is formed with a discharge hole for the transfer fluid, and is disposed on the outer periphery of the columnar protrusion, one end of which is fixed to the pump body, and the other end closed portion is close to the tip surface of the columnar protrusion. A bellows that expands and contracts between a discharge stroke end position and a suction stroke end position that is separated from the tip surface of the columnar protrusion,
A reciprocating drive device connected to the bellows for expanding and contracting the bellows, and facing the columnar protrusion at the other end closing portion of the bellows at the discharge stroke end position on the outer periphery of the inlet of the discharge hole. The invention is characterized in that an annular seal protrusion that locally abuts the surface is provided.

According to the first aspect of the present invention, the inside of the bellows is made negative pressure by the suction process for expanding the bellows, and the fluid to be transferred is sucked into the discharge hole through the suction hole and the passage. In addition, the inside of the bellows is pressurized by the discharge process of contracting the bellows, and the fluid to be transferred sucked into the discharge holes is discharged. That is, the fluid to be transferred is intermittently discharged by expanding and contracting the bellows, and the discharge amount can be determined by the discharge stroke. on the other hand,
At the end position of the discharge step, the annular seal protrusion projecting on the outer periphery of the inlet of the discharge hole locally abuts on the opposite surface of the bellows at the other end closed portion to the columnar protrusion. It has a high surface pressure and a high sealing property, and can block the inlet of the discharge hole. Therefore, even if a force that causes the transferred fluid to flow out from the discharge hole due to inertia after the end of the discharge process, it is possible to reliably prevent the transferred fluid from flowing out at the end of the discharge step.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention; FIG. 1 is a vertical cross-sectional view showing an embodiment of the invention described in claim 1. In this figure, 1 is a disk-shaped pump body, and a cylindrical protrusion 2 is integrally formed at one end in the axial direction. Is provided in
These are molded from PTFE (polytetrafluoroethylene plastic resin) or PFA (perfluoroalkoxy fluororesin). Of the outer peripheral surface of the cylindrical protruding portion 2, the outer peripheral surface 2a of the tip side portion corresponding to the movable portion of the bellows, which will be described later, is formed into a tapered surface having a gradually decreasing diameter toward the tip portion side, and The outer peripheral surface 2b of the base end side portion corresponding to the immovable portion of the bellows is formed to have a uniform outer diameter in the axial direction.

Reference numeral 3 denotes a suction hole for the fluid to be transferred, which is formed at a position deviated from the central axis of the pump body 1.
The tip of the suction hole 3 is opened at the base end of the columnar protrusion 2, and the side surface from the opening 3a to the tip 2t of the columnar protrusion 2 is shown in FIG. Thus, the groove-shaped passage 4 having a substantially U-shaped cross section is formed so as to communicate with the suction hole 3.

An elbow joint body 5A is attached to one side of the pump body 1 by screwing, and an elbow joint body 5B is attached to the other side of the pump body 1 by screwing.
The outlet side of the passage 5a of the elbow type joint body 5A has a suction hole 3
Is connected to the suction hole 3 via a spring-type check valve 6A that allows the flow in the opposite direction and stops the flow in the direction opposite to the suction hole 3. The spring type check valve 6A includes a check valve body 6a.
1 and a spring 6a2. At the inlet side of the passage 5a of the elbow type joint main body 5A, the fluid transfer pipe 7A is press-fitted into one end portion of the transferred fluid supply pipe 7A made of resin.
Inner ring 8A for expanding A, this inner ring 8
A cylindrical receiving port 9A for inserting the end of the fluid supply pipe 7A expanded by A and one end of the joint body 5A are screwed together to press the inner ring 8A from the outside of the fluid supply pipe 7A for sealing. The transferred fluid pipe 7A is connected via a pipe joint 12A composed of a push wheel 10A that applies force.

A discharge hole 11 for the fluid to be transferred is formed at a position deviated to the opposite side of the suction hole 3 with respect to the central axis of the pump body 1, and the inlet thereof is the tip end surface of the cylindrical projection 2. The opening is open at 2t, and the outlet allows the flow in the direction of the discharge hole 11 and the elbow-type joint main body 5B through the check valve 6B of the spring type which stops the flow in the direction opposite to the discharge hole 11B.
Is connected to the entrance side of the passage 5b. The spring type check valve 6B includes a check valve body 6b1 and a spring 6b2. An inner ring 8B, which is press-fitted into one end of the transferred fluid discharge pipe 7B made of resin to expand the diameter of the fluid discharge pipe 7B, on the outlet side of the passage 5b of the elbow type joint body 5B. The cylindrical receiving port 9B for inserting the end of the fluid discharge pipe 7B and the one end of the joint body 5B are screwed together to press the inner ring 8B from the outside of the fluid discharge pipe 7B to provide a sealing force. Push ring 1
Transfer fluid discharge pipe 7 via pipe joint 12B made of 0B
B is connected.

A bellows 13 having a fold 13A is arranged on the outer periphery of the cylindrical protrusion 2. One end of the bellows 13 is brought into contact with one side surface of the pump body 1, and the fixing plate 14
Is fixed to the pump body 1 via a cylindrical protrusion 2 at the other end as the bellows 13 expands and contracts.
The closing portion 13B is provided so as to approach and separate from the front end surface 2t.

On the other hand, as shown in FIG.
As also shown, an annular seal projection 16 is provided. The cross-sectional shape of the annular seal projection 16 is trapezoidal. Therefore, at the discharge stroke end position of the bellows 13, the facing surface 13b of the closed portion 13B facing the tip end surface 2t of the columnar protrusion 2 locally abuts.
Reference numeral 15 in the drawing denotes a reciprocating body such as a piston rod that is reciprocally moved in the axial direction by a drive source such as a fluid cylinder (not shown), and a central portion of the closing portion 13B of the bellows 13 is provided at the tip of the reciprocating body 15. The bellows 13 are connected to each other, and the bellows 13 is expanded and contracted by the reciprocating movement of the reciprocating body 15.

In the above structure, the bellows 13 expands and contracts by reciprocating the reciprocating body 15 in the direction of arrow XY in FIG. 1 with a predetermined stroke by driving the drive source. The inside of the bellows 13 is negatively pressured by the suction stroke (in the direction of the arrow X) for extending the bellows 13. For this reason, the transferred fluid passes through the transferred fluid supply pipe 7A, the passage 5a of the elbow-type joint body 5A, the check valve 6A, and the suction hole 3 in the groove-shaped passage 4, the closing portion 13B, and the cylindrical protruding portion. 2t end face 2t
It is sucked into the space surrounded by. In addition, the bellows 13 is caused by the discharge process (direction of the arrow Y) for contracting the bellows 13.
The inside of is pressurized. As a result, the transferred fluid in the space is pushed into the discharge hole 11, and the transferred fluid discharge pipe 7 is passed through the check valve 6B and the passage 5b of the elbow type joint body 5B.
B is discharged. That is, the fluid to be transferred is intermittently discharged by expanding and contracting the bellows 13, and the discharge amount can be determined by the discharge stroke.

At the end position of the discharge step, the annular seal protrusion 16 protruding from the outer periphery of the inlet of the discharge hole 11 faces the tip end surface 2t of the columnar protrusion 2 in the other end closing portion 13B of the bellows 13. It locally abuts the surface 13b. Since the seal projection 16 has a trapezoidal cross-section, the apex having a small area comes into contact with the facing surface 13b, so that the surface pressure of the abutting portion is increased and the sealing performance is high. The inlet of the discharge hole 11 can be closed. Therefore, even if a force is exerted on the transferred fluid from the discharge holes 11 due to inertia after the end of the discharge stroke, the transferred fluid is reliably prevented from flowing out at the end of the discharge stroke, and the discharge amount is determined by the discharge stroke. Accurate quantitative transfer can be performed.
Further, even when the operation of the bellows type metering pump is stopped for a relatively long time for maintenance or the like, the transferred fluid does not leak from the transferred fluid discharge pipe 7B during the stop, so that the transferred fluid is prevented from flowing out to the transferred fluid discharge pipe 7B. There is no need to install a valve or check valve. Therefore, the structure of the attached piping system can be simplified as compared with the conventional bellows type metering pump.

In the above embodiment, the pump body 1 is provided with the cylindrical protrusion 2 integrally, but the pump body 1 is integrally provided with the prismatic protrusion 2. May be Further, instead of the groove-shaped passage 4 having a substantially U-shaped cross section formed on the side surface of the columnar protrusion 2, the passage 4 having a circular cross section may be formed in the columnar protrusion 2. Further, the outer peripheral surface 2 of the tip side portion of the cylindrical protrusion 2
It is not always necessary to form a on the tapered surface having a smaller diameter toward the tip end side. That is, the outer diameter of the cylindrical protrusion 2 may be uniform.

Further, although the discharge hole 11 has been described as being formed at a position deviated to the opposite side of the suction hole 3 with respect to the central axis of the pump body 1, the discharge hole 11 is formed at the center of the pump body 1. It may be formed on the axis. With this configuration, the central portion of the facing surface 13b of the bellows 13 comes into contact with the ring-shaped seal projection 16, and thus the bellows 1
3, the opposed surface 13b of the bellows 13 presses the annular seal projection 16 with a uniform force, as compared with the structure in which the portion of the opposed surface 13b of the third portion near the fold 13A abuts the annular seal projection 16. . Therefore, compared to the case of pressing with a non-uniform force, deterioration of the sealing property is avoided, and further,
A high sealing property can be secured.

[0020]

As described above, according to the present invention, the annular seal projection projecting on the outer periphery of the inlet of the discharge hole at the discharge process end position is the columnar projection at the other end closing portion of the bellows. Since it locally abuts on the surface opposed to, it is possible to increase the surface pressure of the abutting portion, have a high sealing property, and close the inlet of the discharge hole. Therefore, even if a force that causes the transferred fluid to flow out from the discharge hole due to inertia after the discharge stroke is completed, the transferred fluid can be reliably prevented from flowing out at the end of the discharge process. Accurate quantitative transfer can be performed. Further, even when the operation of the bellows type metering pump is stopped for a relatively long time for maintenance, the transferred fluid does not leak during the stop, so there is no need to provide an outflow prevention valve or a backflow prevention valve. Therefore, the structure of the attached piping system can be simplified as compared with the conventional bellows type metering pump.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the invention described in claim 1;

FIG. 2 is an enlarged sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view showing a main part of the invention according to claim 1.

FIG. 4 is a longitudinal sectional view showing a main part of a conventional bellows type metering pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump body 2 Cylindrical protrusion (protrusion) 2t Tip surface of protrusion 3 Suction hole 3a Suction hole opening 4 U-shaped groove-like passage (passage) 11 Discharge hole 13 Bellows 13B Bellows closing 13b Closing Facing the columnar protrusions in 15 Reciprocating body (reciprocating drive device) 16 Annular seal protrusion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-279851 (JP, A) Actual development Sho 63-10278 (JP, U) Actual public Sho 61-35750 (JP, Y2)

Claims (1)

(57) [Claims] 1. A columnar protrusion is provided, a suction hole for the fluid to be transferred is formed by opening at a base end of the columnar protrusion, and the columnar protrusion is opened from the opening of the suction hole. A pump body having a passage communicating with the suction hole is formed to extend to the tip, and a discharge hole for the fluid to be transferred is formed at the tip of the columnar protrusion, and the pump body is arranged on the outer periphery of the columnar protrusion. One end is fixed to the pump body and the other end is closed between the discharge stroke end position where the closed end approaches the tip end surface of the columnar protrusion and the suction stroke end position separated from the tip end surface of the columnar protrusion. A bellows that expands and contracts and a reciprocating drive device that is connected to the bellows to expand and contract the bellows are provided, and a columnar shape at the other end closing portion of the bellows at the discharge stroke end position is provided on the outer periphery of the inlet of the discharge hole. of A bellows-type metering pump, characterized in that an annular seal protrusion that locally abuts is provided on a surface facing the protrusion.