JPH0988831A - Bellows-type fixed displacement pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure of accompanying piping by reliably preventing transported fluid from flowing out after a discharge stroke ends, correctly transporting the discharge quantity determined by the discharge stroke and by eliminating a flow control valve and a by-pass passage or a flow-out preventing valve. SOLUTION: An annular sealing projection 16 which locally abutts on the surface opposite to a pillar-like projection of a sealing plate 11 at the end position of the discharge stroke of the bellows 9 is made at the outer periphery of the passage 18 communicating with a suction port 2 formed in a pump body 1 to increase interfacial pressure at the contact part, thereby closing the outlet of the passage 18 by increased sealing performance.

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 desired to be metered.

[0002]

As a bellows type metering pump of this type,
Conventionally, the one disclosed in Japanese Utility Model Publication No. 61-35750 is known. FIG. 5 shows the structure of the 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 transferred fluid has a cylindrical shape. Forming a protrusion 33,
On the central axis of the cylindrical protrusion 33, a flow hole 34 is formed, one end of which communicates with the suction hole 30 and the other end of which opens at the tip surface of the cylindrical protrusion 33, and the discharge hole 31. At the inner end position of the annular gap 36 between the inner circumference of the bellows 35 arranged on the outer circumference of the cylindrical protrusion 33 and the 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 sealing 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.
In addition, the inside of the bellows 35 is pressurized by the discharge process of contracting the bellows 35, and the transferred fluid sucked into the annular gap 36 is discharged through the annular groove 37 and the discharge hole 31. That is, the reciprocating drive device allows the bellows 35
The fluid to be transferred is intermittently discharged by expanding and contracting, and the discharge amount is determined by the discharge stroke (discharge stroke), so it is expected that quantitative transfer can be expected.

However, the annular gap 36 and the annular groove 37 are formed.
The fluid inside has a force that flows toward the discharge hole 31 due to inertia even after the discharge stroke is completed. Moreover, at the end position of the discharge step, the seal plate 39 contacts the one end surface of the bellows 35 and the tip end surface of the cylindrical protrusion 33 with a relatively large area to close the annular gap 36 and the flow hole 34. Therefore, the surface pressure of the contact portion is low and high sealing performance cannot be expected. Therefore, after the discharge stroke is completed, the transferred fluid in the annular gap 36 and the annular groove 37 is discharged into the discharge hole 3
By flowing toward 1 and flowing out, the annular gap 36
Even if the inside of the valve is made negative, the surface pressure of the abutting portion cannot be increased by this negative pressure to reliably seal, so that the flow hole is restored until the negative pressure of the annular gap 36 is recovered. 34
The fluid to be transferred inside continues to flow into the annular gap 36 and continues to flow out from the discharge hole 31 even after the end of the discharge process, which hinders quantitative 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, it is necessary to prevent the transferred fluid from flowing out for the above reason. For this reason, the intersection of the suction hole 30 and the flow hole 34 is extended to the opposite side of the flow hole 34, and the outlet of the flow rate control valve 41, which is, for example, a needle valve, is connected to the inlet side of the flow rate control valve 41. And discharge hole 31
Are connected by a bypass passage 42, and the transferred fluid flowing out of the discharge hole 31 is circulated from the bypass passage 42 to the circulation hole 34 even after the discharge stroke is completed, or is prevented from flowing out to the discharge pipe connected to the discharge hole 31. Since it is necessary to install a valve, the structure of the attached piping system is complicated.

[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 had a drawback that the quantitative transfer was hindered. Therefore, the structure of the attached piping system is complicated. In view of this, the invention according to claim 1 enhances the sealing property of the suction side at the end position of the discharge step to reliably prevent the transferred fluid from flowing out after the end of the discharge stroke, and to determine the discharge stroke determined by the discharge stroke. It is possible to provide a bellows-type metering pump that can accurately carry out quantitative transfer according to the amount of flow and does not require a flow rate control valve, a bypass passage or an outflow prevention valve, and can simplify the structure of an attached piping system. It is intended. In addition, claim 2
According to the invention described above, by enhancing the sealing property on the discharge side at the discharge process end position, the outflow of the transferred fluid after the discharge stroke is reliably prevented, and the discharge amount determined by the discharge stroke is accurately determined. The purpose of the present invention is to provide a bellows type metering pump that is capable of transferring and does not require a flow rate control valve and a bypass passage or an outflow prevention valve and can simplify the structure of an attached piping system. is there.

[0008]

In order to achieve the above object, a bellows type metering pump according to the invention of claim 1 is formed with a suction hole and a discharge hole for a transfer fluid and communicates with the suction hole. A pump body having a columnar protrusion having a passage formed therein and having the discharge hole opened around the base end of the columnar protrusion, and a pump body provided around the columnar protrusion and having an opening at one end. Is fixed to the pump body in communication with the opening of the column, and the other end closing portion approaches the tip end surface of the columnar protrusion to close the outlet of the passage and the discharge stroke end position and the tip end surface of the columnar protrusion. And a reciprocating drive device that is connected to the bellows and that causes the bellows to expand and contract, and that extends and contracts between the suction stroke end position and the suction stroke end position. It is obtained by said the locally abuts annular seal projection on the facing surface of the columnar protrusions are provided at the other end closed portion of the bellows at the end position degree. Further, the bellows type metering pump according to the invention of claim 2 has a columnar protrusion having a suction hole and a discharge hole for the transfer fluid and a passage communicating with the discharge hole, and the columnar protrusion. A pump body in which the suction hole is opened around the base end portion of, and is provided around the columnar protrusion, and one end opening portion is connected to the opening of the suction hole and is fixed to the pump body, Telescopic movement between the discharge stroke end position where the other end closing portion approaches the tip end surface of the columnar protrusion to close the inlet of the passage and the suction stroke end position separated from the tip end surface of the columnar protrusion. And a reciprocating drive device connected to the bellows for expanding and contracting the bellows, and a column at the other end closed portion of the bellows at the discharge stroke end position on the outer periphery of the inlet of the passage. It is obtained by said to locally contact with annular seal projections on the surface facing the protruding portion of the is provided.

According to the first aspect of the present invention, the inside of the bellows is made negative pressure by the suction stroke for expanding the bellows, and the transferred fluid is sucked into the discharge hole through the path of the suction hole and the passage. Further, the discharge process of contracting the bellows pressurizes the inside of the bellows and discharges the transferred fluid sucked into the discharge holes. That is, the transferred fluid 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 projection, which is provided on the outer periphery of the outlet of the passage, locally contacts the surface of the bellows opposite to the columnar projection at the other end closed portion. The surface pressure is increased and the sealing property is high, so that the outlet of the passage can be closed. Therefore, even if the force that flows out from the discharge hole acts on the transferred fluid due to the inertia after the discharge stroke,
Since the transferred fluid in the passage can be prevented from flowing toward the discharge hole, the transferred fluid can be reliably prevented from flowing out at the end of the discharging process.

According to the second aspect of the present invention, the inside of the bellows is made negative pressure by the suction stroke for expanding the bellows, and the fluid to be transferred is sucked into the passage and the discharge hole through the suction hole and the passage. In addition, the discharge process of contracting the bellows pressurizes the inside of the bellows to discharge the fluid to be transferred that has been sucked into the passage and the discharge hole. That is, the transferred fluid 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 process, the annular seal projection protruding from the outer circumference of the inlet of the passage locally abuts the surface of the other end of the bellows facing the columnar projection at the other end of the bellows. The surface pressure of the portion is increased and the sealing property is high, so that the inlet of the passage can be closed. Therefore,
Even if a force is exerted on the transferred fluid from the discharge holes due to inertia after the end of the discharge process, the transferred fluid can be reliably prevented from flowing out at the end of the discharge step.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 will be described below with reference to the drawings. FIG. 1 is a vertical sectional view showing an embodiment of the invention described in claim 1. In this figure, a disc-shaped pump body 1 is provided with a suction port 2 for the fluid to be transferred and a discharge hole 3 for the fluid to be transferred, and a cylindrical protrusion 17 is provided at one end of the pump body 1 in the axial direction. It is provided integrally. The pump body 1 and the columnar protrusion 17 are molded of PTFE (polytetrafluoroethylene plastic resin) or PFA (perfluoroalkoxy fluororesin). The suction hole 2 extends to the vicinity of the center line of the cylindrical protrusion 17, and its outlet communicates with a passage 18 formed on the center line.
The outlet of is opened at the tip of the cylindrical protrusion 17. An annular groove 19 is formed on one side surface of the pump body 1 surrounding the outer periphery of the base end portion of the columnar protrusion 17, and the inlet of the discharge hole 3 is opened in the annular groove 19.

A suction unit 4 is provided in the suction hole 2,
A discharge unit 5 is provided in the discharge hole 3. The suction unit 4 and the discharge unit 5 are respectively provided with a valve retainer 6,
A check valve 8 of a spring type is provided, which is pressed and fixed by a holding nut 7 and a valve retainer 6. The spring type check valve 8 includes a check valve body 8A and a spring 8B, and the check valve 8 of the suction unit 4 allows only a flow in the suction hole 2 direction and a flow in the counter suction hole 2 direction. The check valve 8 of the discharge unit 5 allows only the flow in the discharge direction (the direction opposite to the discharge hole 3) and blocks the flow in the discharge hole 3 direction. .

A bellows 9 having pleats 9A is arranged on the outer periphery of a cylindrical protrusion 17. The open one end 9B of the bellows 9 is brought into contact with one side surface of the pump body 1 and is fixed to the pump body 1 via a fixing plate 10, and the open other end 9C is closed via a sealing plate 11. It is closed by 12, and is sandwiched between the closing plate 12 and the mounting plate 13. The closing plate 12 is screwed into the ring body 14 that holds down the mounting plate 13.

On the other hand, an annular seal projection 16 is provided on the outer periphery of the outlet of the passage 18 as shown in FIG. The annular seal projection 16 has a trapezoidal cross section. Therefore, the annular seal protrusion 16
Is the bellows 9 at the discharge stroke end position of the bellows 9.
Locally abuts on the surface of the closed portion of the columnar protrusion 17 facing the tip surface 17t, that is, the inner surface of the seal plate 11. Reference numeral 15 in the drawing denotes a reciprocating body such as a piston rod which is reciprocally moved in the axial direction by a drive source such as a fluid cylinder (not shown). The reciprocating body 15 has a tip end portion to which a closing plate 12 is connected. The bellows 13 expands and contracts as the moving body 15 reciprocates.

A passage 6a is formed through the valve retainer 6 in the suction unit 4 on the centerline thereof, and a passage 6a is formed through the centerline of the valve retainer 6 in the discharge unit 5. At the inlet side of the passage 6a of the valve retainer 6 in the suction unit 4, an inner ring 21A which is press-fitted into one end of a fluid transfer pipe 20A made of resin to expand the diameter of the fluid supply pipe 20A, and the inner ring 21A. The inner ring 21A is screwed onto the cylindrical receiving port 22A for inserting the end of the fluid supply pipe 20A and the outer end of the valve retainer 6 to insert the inner ring 21A into the fluid supply pipe 20A.
The transferred fluid pipe 20A is connected via a pipe joint 24A made up of a push ring 23A that is pressed from the outside to give a sealing force. Further, on the outlet side of the passage 6a of the valve retainer 6 in the discharge unit 5, the transferred fluid discharge pipe 20 made of resin is provided.
An inner ring 21B which is press-fitted into one end portion of B to expand the diameter of the fluid discharge pipe 20B, a cylindrical receiving port 22B and a valve for inserting the end portion of the fluid discharge pipe 20B expanded by the inner ring 21B. A pipe joint 24 composed of a push ring 23B that is screwed onto the outer end of the presser 6 to press the inner ring 21B from the outside of the fluid discharge pipe 20B to provide a sealing force.
The transferred fluid discharge pipe 20B is connected via B.
In the figure, reference numeral 26 denotes a support base, which includes the pump body 1 and the reciprocating body 1.
We support 5 and 5.

In the above construction, the bellows 9 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 9 is made negative pressure by the suction stroke (direction of arrow X) for extending the bellows 9. Therefore, the transferred fluid is
The fluid to be transferred 20 A, the passage 6 a of the valve retainer 6, the check valve 6 A, the suction hole 3, and the passage 18 are sucked into the space surrounding the cylindrical protrusion 17 in the internal space of the bellows 9. . Further, the interior of the bellows 9 is pressurized by the discharge process (the direction of the arrow Y) that contracts the bellows 9.
As a result, the transferred fluid in the space is pushed into the discharge hole 3 and discharged into the transferred fluid discharge pipe 20B through the check valve 6B and the passage 6a of the valve retainer 6. That is, the fluid to be transferred is intermittently discharged by expanding and contracting the bellows 9, and the discharge amount can be determined by the discharge stroke.

At the end position of the discharge step, the annular seal projection 16 projecting from the outer periphery of the outlet of the passage 18 is provided with the tip end surface 17 of the columnar projection 17 at the other end closing portion of the bellows 9.
It locally abuts the surface facing t, that is, the inner surface of the seal plate 11. Since the seal projection 16 has a trapezoidal cross-section, the top portion having a small area comes into contact with the seal plate 11, so that the surface pressure of the contact portion is increased and the sealing performance is high. The outlet of the passage 18 can be blocked. Therefore, even if a force that causes the transferred fluid to flow out of the discharge hole 3 due to inertia after the end of the discharge stroke, the transferred fluid in the passage 18 can be prevented from flowing toward the discharge hole 3, and therefore, at the end of the discharge stroke. In this case, the transferred fluid can be surely prevented from flowing out, and the fixed amount can be accurately transferred with the discharge amount determined by the discharge stroke. Further, even when the operation of the bellows type metering pump is stopped for a relatively long time for maintenance or the like, since the transferred fluid does not leak from the transferred fluid discharge pipe 21B during the stop, the flow rate control to the transferred fluid discharge pipe 20B is performed. It is not necessary to provide a valve and a bypass passage or an outflow prevention valve. Therefore, the structure of the attached piping system can be simplified as compared with the conventional bellows type metering pump.

FIG. 3 is a longitudinal sectional view showing an embodiment of the invention as defined in claim 2. The same parts as those in the embodiment of the present invention described in claim 1 described with reference to FIGS. 1 and 2 are designated by the same reference numerals, and detailed description of the structure will be omitted. As shown in FIG. 4, the invention according to claim 2 has a columnar projecting portion at the other end closing portion of the bellows 9 at the discharge stroke end position on the outer periphery of the inlet of the passage 18 communicating with the discharge hole 3. It is characterized in that an annular seal projection 16 that locally abuts is provided on the surface facing 17 and the inner surface of the seal plate 11.

With such a structure, the bellows 9 expands and contracts by reciprocating the reciprocating body 15 in the direction of arrow XY in FIG. 3 with a predetermined stroke by driving the drive source.
The inside of the bellows 9 is made negative pressure by the suction stroke (direction of arrow X) for extending the bellows 9. Therefore, the transferred fluid is supplied to the transferred fluid supply pipe 20A and the passage 6 of the valve retainer 6.
A, the check valve 6A, the suction hole 3, and the passage 18 are sucked into the space surrounding the cylindrical protrusion 17 in the internal space of the bellows 9. Further, the interior of the bellows 9 is pressurized by the discharge process (the direction of the arrow Y) that contracts the bellows 9. As a result, the transferred fluid in the space is discharged into the discharge hole 3
The check valve 6B and the passage 6a of the valve retainer 6 are pushed in.
Is discharged to the transferred fluid discharge pipe 20B. That is, the fluid to be transferred is intermittently discharged by expanding and contracting the bellows 9, and the discharge amount can be determined by the discharge stroke.

At the end position of the discharge step, the annular seal projection 16 projecting from the outer periphery of the inlet of the passage 18 is provided with the tip end surface 17 of the columnar projection 17 at the other end closing portion of the bellows 9.
It locally abuts the surface facing t, that is, the seal plate 11. Since the seal projection 16 is formed in a trapezoidal cross-section, the top having a small area comes into contact with the seal plate 11, so that the surface pressure of the contact portion is increased and high sealing performance is achieved. The outlet of the passage 18 can be blocked. Therefore, even if the force to flow out from the discharge hole 3 acts on the transferred fluid due to the inertia after the end of the discharge stroke, the transferred fluid is surely prevented from flowing out at the end of the discharge step, and the discharge amount determined by the discharge stroke is set. 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 is not transferred to the transferred fluid discharge pipe 21B during the stop.
There is no need to provide a flow rate control valve, a bypass passage, an outflow prevention valve, or the like in the transferred fluid discharge pipe 20B, because it does not leak from the pipe. Therefore, the structure of the attached piping system can be simplified as compared with the conventional bellows type metering pump.

Although the pump body 1 is integrally provided with the cylindrical protrusion 2 in the above embodiment, the pump body 1 is integrally provided with the prismatic protrusion 2. May be

[0022]

As described above, according to the first aspect of the present invention, the annular seal protrusion projecting on the outer periphery of the outlet of the suction hole at the end position of the discharge step is at the other end closing portion of the bellows. Since it locally abuts the surface facing the columnar protrusion, the surface pressure of the abutting portion can be increased and the inlet of the discharge hole can be blocked with a high sealing property. Therefore, even if a force that causes the transferred fluid to flow out from the discharge hole due to the inertia after the discharge process is completed, it is possible to prevent the transferred fluid in the passage from flowing toward the discharge hole. It is possible to reliably prevent the fluid from flowing out, and it is possible to accurately carry out the quantitative transfer with the discharge amount determined by the discharge stroke. In addition, even when the operation of the bellows type metering pump is stopped for a relatively long time for maintenance,
Since the transferred fluid does not leak during the stop, it is not necessary to provide a flow rate control valve and a bypass passage or an outflow prevention valve. Therefore, the structure of the attached piping system can be simplified as compared with the conventional bellows type metering pump. According to the second aspect of the present invention, the annular seal projection, which is provided on the outer periphery of the inlet of the discharge hole at the discharge step end position, faces the columnar projection at the other end closing portion of the bellows. Since the abutment portion locally abuts, the surface pressure of the abutting portion can be increased, and the inlet of the discharge hole can be closed with a high sealing property. 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 if 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 a flow control valve and a bypass passage or an outflow 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 drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of the invention according to claim 1.

FIG. 2 is an enlarged view showing a main part of the invention according to claim 1.

FIG. 3 is a longitudinal sectional view showing an embodiment of the invention as set forth in claim 2.

FIG. 4 is an enlarged view showing a main part of the invention according to claim 2;

FIG. 5 is a vertical cross-sectional view showing a main part of a conventional bellows type metering pump.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pump body 2 Suction hole 3 Discharge hole 9 Bellows 11 Seal plate (the other end of the bellows closing part) 13B One end of the bellows 13C The other end of the bellows the other end closing part 15 Reciprocating body (reciprocating drive device) 16 Annular seal protrusion Part 17 Cylindrical protrusion (columnar protrusion) 17t Tip surface of columnar protrusion 18 Passage

Claims (2)

[Claims] 1. A columnar projection having a suction hole and a discharge hole for a transfer fluid and a passage communicating with the suction hole is provided, and the discharge hole is opened around a base end of the columnar projection. And a pump body provided around the columnar protrusion, and the one end opening communicates with the opening of the discharge hole and is fixed to the pump body, and the other end closing part has the tip of the columnar protrusion. A bellows that extends and contracts between a discharge stroke end position that closes the outlet of the passage and closes the outlet of the passage and a suction stroke end position that is separated from the tip end surface of the columnar protrusion, and the bellows connected to the bellows. A reciprocating drive device for expanding and contracting the bellows, and an annular ring that locally abuts on the outer periphery of the outlet of the passage at the end of the discharge stroke, the surface facing the columnar protrusion in the other end closing portion of the bellows. The bellows type metering pump is characterized in that a seal protrusion is provided. 2. A columnar projection having a suction hole and a discharge hole for the transfer fluid and a passage communicating with the discharge hole, and the suction hole being opened around the base end of the columnar projection. And a pump body that is provided around the columnar protrusion, and the one end opening communicates with the opening of the suction hole and is fixed to the pump body, and the other end blocking part is the tip of the columnar protrusion. A bellows that expands and contracts between a discharge stroke end position that closes the inlet of the passage to close the surface and a suction stroke end position that is separated from the tip end surface of the columnar protrusion, and is connected to the bellows. A reciprocating drive device for expanding and contracting the bellows, and an annular ring that locally abuts on the outer periphery of the inlet of the passage at the end of the discharge stroke, the surface facing the columnar protrusion in the other end closing portion of the bellows. The bellows type metering pump is characterized in that a seal protrusion is provided.