JP3504905B2 - Resin spring for check valve of metering pump and bellows metering pump using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a resin spring used as a spring for a check valve provided in a fluid handling device such as various pumps and valves, and a resin spring incorporated therein. For example, the present invention relates to a bellows-type metering pump used for transferring a fluid for which a fixed transfer without retention is desired.

[0002]

2. Description of the Related Art In a spring installed and used in the flow path of a fluid to be handled, the spring should not corrode or rust, that is, chemical resistance and rust prevention. What is excellent is demanded. Conventionally, PTFE and PFA have been used as springs that meet such demands.
The entire outer surface of the resin spring or metal spring formed by molding fluororesin into a coil
A resin-coated spring formed by coating with a fluororesin such as PFA or PFA is known.

Further, in the conventional bellows type metering pump for handling a transferred fluid such as a chemical solution or pure water which is particularly required to have chemical resistance and rust prevention among the handled fluids, it is formed on the pump body. The check valve provided at the base end of the suction hole and the tip of the discharge hole to allow the flow of the transferred fluid only in the suction direction and the discharge direction and block the flow in the reverse direction. A resin spring formed by molding a fluororesin such as PTFE or PFA into a coil has been used as the elastically biasing spring.

[0004]

In the conventional resin spring having the above-described structure, the repulsive force is weak, and even if the strength (spring force) close to that of the metal spring is initially obtained, it can be repeatedly used. There is a significant settling of the resin, and it is unavoidable that the strength of the resin decreases with time due to creep of the resin, particularly thermal creep. Further, when the resin-coated spring has a particularly small shape, it is technically very difficult to manufacture, and not only the cost becomes very high, but also the peeling of the coating resin causes a predetermined chemical resistance and rust resistance. I could not keep it.

On the other hand, as a spring in the check valve,
In the conventional bellows type metering pump using the coiled resin spring as described above, when the discharge port is installed at a position lower than the suction tank and used, the discharge pressure is higher than the head pressure of the tank. Is small, the spring load value that biases the valve element in the check valve on the tip side of the discharge hole in the closing direction is small, so a siphon phenomenon occurs during the discharge action and the check valve on the base side of the suction hole is generated. However, there is a problem that the valve body unexpectedly opens below the head pressure of the tank, the internal pressure of the pump is not generated, a large amount of fluid flows, the discharge amount increases, and a predetermined quantitativeness cannot be secured.
In addition, conventional coil-shaped resin springs
Since the strength decreases with time due to thermal creep, the quantitative property could not be stably maintained at both normal temperature and high temperature for long-term use.

The present invention has been made in view of the above circumstances, and it is possible to give strength close to that of a metal spring with a resin alone, and further, to prevent the strength from decreasing with time, and for a long period of time. The main purpose is to provide a resin spring that can maintain the required strength.

Another object of the present invention is to make effective use of the characteristics of the resin spring as described above so that the discharge port is installed at a position lower than the suction tank, and the discharge is repeated within a range from room temperature to high temperature. It is an object of the present invention to provide a bellows type metering pump capable of preventing the occurrence of the siphon phenomenon and stably maintaining a predetermined metering property even under the condition of performing the above.

[0008]

In order to achieve the above main object, a resin spring according to the invention of claim 1 is
The belt-shaped sheet made of fluororesin is bent in a zigzag shape with a predetermined bulging curvature along its longitudinal direction, and the side surfaces of adjacent bent portions with a predetermined curvature come close to or in contact with each other. Compressed state
Is formed so as to have a free length , and the bent portions having a predetermined curvature are configured to be elastically expandable and contractible by heating and holding and cooling , and further compressing force may be applied in the free length direction.
It is characterized by expressing repulsive force with .

According to the first aspect of the present invention having the above structure, the fluororesin belt-shaped sheet is bent in a zigzag shape with a predetermined bulge-shaped curvature, and the side surfaces of adjacent bent portions having a predetermined curvature are adjacent to each other. Since the free lengths are formed so that they are close to or in contact with each other, by further applying a compressive force to them, the bulge-shaped curvature of each bent portion increases, and the increased curvature The force to restore the original bulge-like curvature collects and a large repulsive force is expressed.Therefore, compared with the conventional coil-shaped resin spring, the aging due to repeated use and the creep due to resin creep Very little decrease in strength. Further, since the bent portion having the predetermined curvature is configured to be elastically expandable and contractible by heating and holding and cooling,
It has resilience to withstand the use of heat,
Even in the heat cycle, the repulsive force and the strength hardly decrease, and the initial strength can be maintained. Moreover, it is possible to provide the above-mentioned repulsive force and strength with the resin alone, and the manufacturing is simpler and the cost can be largely reduced as compared with the conventional resin-coated spring.

In the resin spring according to the invention described in claim 1, as the fluororesin constituting the strip-shaped sheet, as described in claim 2, PTFE excellent in creep property and thermal creep property is preferable. In addition, as the specifications of the belt-shaped sheet, in order to develop a predetermined repulsive force,
As described in claim 3, the thickness is 0.05 to 1.0 mm.
It is preferable that the radius of curvature of each bent portion is 0.05 mm or more. Furthermore, the heating and holding temperature in the compressed state is 100 to 300 ° C., preferably around 200 ° C., and cooling is preferably carried out by putting in water and rapidly cooling to room temperature.

In the bellows type metering pump according to a fourth aspect of the present invention, an opening is formed at the end face of the circular protrusion having a suction hole for the fluid to be transferred and a fluid passage communicating with the suction hole. And a pump body in which a discharge hole for the fluid to be transferred is formed, and one end of the pump body is fixed to the pump body and the other end is closed. A bellows that expands and contracts between a compression end position in contact with the end face of the tip and an extension end position separated from the end face of the cylindrical protrusion, and a bellows connected to the bellows to extend and contract. A reciprocating drive device, a check valve provided at the base end of the suction hole to allow the flow of the transferred fluid only in the suction direction, and a check valve provided at the tip of the discharge hole only in the discharge direction of the transferred fluid. Reverse to allow the flow of A bellows type metering pump comprising a valve, wherein as a spring for elastically biasing at least a valve element of the check valve on the discharge hole side in the check valve among the two check valves in the closing direction. A resin spring having any one of the configurations described above is used.

According to the fourth aspect of the present invention having the above-mentioned structure, since the spring load value for urging the valve body in the check valve on the tip side of the discharge hole in the closing direction can be made large, the discharge port of the pump is set to be large. Even when installed and used at a position lower than the suction tank, the valve element of the check valve on the discharge hole tip side opens only when a discharge pressure several times higher than the tank head pressure occurs in the bellows. At this time, the valve element of the check valve on the proximal end side of the suction hole is surely closed and held by the pressure in the bellows to oppose the head pressure of the tank.
Therefore, it is possible to prevent a siphon phenomenon from occurring due to the valve body of the check valve on the proximal end side of the suction hole being opened unexpectedly below the head pressure of the tank, and it is possible to ensure a predetermined quantitativeness. Further, since the strength of the resin spring does not decrease with time due to creep and thermal creep, even if it is repeatedly operated in the range of normal temperature to high temperature,
The quantitative property can be stably maintained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a schematic perspective view showing a method for manufacturing a resin spring according to the present invention, FIG. 2 is an enlarged side view of the resin spring manufactured, and the resin spring 20 is shown in FIG. So that the thickness is 0.0
The PTFE band-shaped sheet 21 having a diameter of 5 mm to 1.0 mm is provided with a predetermined bulge-shaped radius of curvature R of 0.05 mm or more along the longitudinal direction thereof to form a zigzag shape as shown in FIG. While being bent, as shown in FIG. 1C, 100 to 300 ° C., preferably in a state in which the side surfaces of the bent portions 21a, 21a, ... Adjacent to each other in the longitudinal direction and having a predetermined curvature are in contact with or close to each other, Is heated to about 200 ° C., and the heating state is maintained for 5 minutes or more, and then put in water and rapidly cooled to room temperature. As shown in FIG. The bent portions 21a ... Are elastically expandable and contractible.

In the PTFE spring 20 constructed as described above, a compressive force G is further applied to the spring 20 as shown in FIG.
The radius of curvature r of ... Is smaller (the curvature is larger) than the radius of curvature R at the free length L, and the force when the reduced radius of curvature r is restored to the original bulge-shaped radius of curvature R is They will come together and develop a large repulsive force. In addition, compared to the conventional coiled resin springs, the deterioration of strength over time due to fatigue and resin creep due to repeated use is very small, and it has resilience to withstand use even when heat is applied. Even in the heat cycle, the repulsive force and the strength hardly decrease, and the initial strength can be maintained .

Incidentally, when the repulsive force between the PTFE spring 20 of the present invention and the conventional coiled resin spring was tested, the results shown in Table 1 below were obtained. As is clear from Table 1, in the conventional coil-shaped resin spring, the repulsive force after a thermal cycle at room temperature to 100 ° C. drops sharply as the thermal cycle progresses,
The repulsive force after heating at 200 ° C. can hardly be expected, while the PTFE spring 20 of the present invention product.
Is excellent in creep property and thermal creep property because the repulsive force after the thermal cycle at room temperature to 100 ° C. is larger than that before the thermal cycle, and the rate of decrease with the progress of the thermal cycle is also very small. The repulsive force after heating at 200 ° C. is hardly reduced. In addition, each value in Table 1 is
The residual value is shown in% when the repulsive force before the test is 100.

[0016]

[Table 1]

Further, regarding both resin springs, M
When a test for bending fatigue was performed by the IT test (ASTM.D2176), the results shown in Table 2 below were obtained. As is clear from Table 2, the PTFE spring 20 of the present invention does not break due to the characteristics of the constituent materials, and therefore, even after repeated operation, it breaks within at least tens of millions of times. It has unique characteristics.

[0018]

[Table 2]

FIG. 4 is a vertical sectional view of a bellows type metering pump according to the present invention. In FIG. 4, reference numeral 1 is a disc-shaped pump body, and a protrusion 2 having a circular sectional shape is integrally formed at one end in the axial direction thereof. Of the outer peripheral surface of the circular protrusion 2, the outer peripheral surface 2a of the tip side portion corresponding to the movable part of the bellows described later has a smaller diameter along the axial direction toward the tip side. The outer peripheral surface 2b of the base end portion, which is formed as a tapered surface and corresponds to the immovable portion of the bellows, is formed as a straight cylindrical surface along the axial direction.

Reference numeral 3 is 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 end of the suction hole 3 is the base end of the circular protrusion 2. As shown in FIG. 5, a groove-shaped fluid having a U-shaped cross section is formed on the side surface of the circular protrusion 2 from the opening to the tip end surface 2t of the circular protrusion 2 as shown in FIG. A passage 4 is formed in communication with the suction hole 3. At the base end of the suction hole 3, the transferred fluid is sucked through a valve retainer 8 with an internal flow passage 8a capable of connecting and connecting the cap nut 5 screwed to the pump body 1 and the transferred fluid pipe 7A. A non-return valve 6 that allows flow in only one direction and blocks flow in the opposite direction is internally held.

Reference numeral 11 denotes a discharge hole for the fluid to be transferred, which is formed at a position deviated to the side opposite to the suction hole 3 with respect to the central axis of the pump body 1.
Has a base end opening at the tip end face 2t of the circular protrusion 2, and at the tip of the discharge hole 11,
The cap nut 9 screwed to the pump body 1 and the transferred fluid pipe 7B are allowed to communicate with each other through the valve retainer 10 with the internal flow path 10a, and the flow of the transferred fluid is allowed only in the discharge direction, and the reverse A check valve 12 for preventing directional flow is internally held.

Reference numeral 13 is a bellows having a fold 13a, which is arranged on the outer circumference of the circular protrusion 2 and one end of which is abutted against one side surface of the pump body 1 so that the fixing plate 14 is provided.
The end face 2 of the tip of the circular protrusion 2 is fixed to the other end as the bellows 13 expands and contracts.
A closing portion 13b that comes into contact with and separates from t is provided. Reference numeral 15 denotes a reciprocating body such as a piston which is reciprocally moved in the axial direction by a reciprocating drive device 16 such as a fluid cylinder. A shaft 17 fixed to the reciprocating body 15 has a tip end portion at which a central portion of the closing portion 13b of the bellows 13 is provided. The bellows 13 are expanded and contracted by the reciprocating movement of the reciprocating body 15.

In the bellows type metering pump having the above construction, the check valve 6 is internally held at the base end side of the suction hole 3 and the check valve 12 is internally held at the tip end side of the discharge hole 11. Are respectively composed of valve seats 6a, 12a, sliding valve bodies 6b, 12b, and springs 6c, 12c for elastically biasing the sliding valve bodies 6b, 12b in the closing direction,
As the springs 6c and 12c, the PTFE spring 20 as described in FIGS. 1 to 3 is used.

In the bellows type metering pump having the above-mentioned structure, the reciprocating body 15 is reciprocated in the direction of arrow XY in FIG. When extended, the block 1
3b is separated from the end surface 2t of the tip of the circular protrusion 2, and the tip of the U-shaped groove-shaped fluid passage 4 is opened to open the bellows 1.
Since the internal space of 3 becomes negative pressure, one fluid pipe 7A
The fluid to be transferred in the inner flow path 8a of the valve retainer 8, the check valve 6,
The closed portion 13b passes through the suction hole 3 and the groove-shaped fluid passage 4.
A certain amount is sucked into the space between the end face 2t of the tip of the circular protrusion 2.

Next, when the bellows 13 is contracted, the closing portion 13b gradually moves closer to the tip end surface 2t of the circular protrusion 2 and finally the tip end surface 2 of the circular protrusion 2 is moved.
It comes into contact with t. During this time, since the transferred fluid sucked into the space is pressurized by the bellows 13, the transferred fluid is pushed into the discharge hole 11, and the check valve 12 and the valve are inserted from the tip thereof. It is discharged into the other fluid pipe 7B through the internal flow path 10a of the presser foot 10. In this manner, the fluid to be transferred is intermittently transferred from the one fluid pipe 7A to the other fluid pipe 7B in accordance with the expansion and contraction operation of the bellows 13 in a fixed amount.

In the bellows type metering pump, as described above, the spring 12c for urging the valve body 12b of the check valve 12 on the tip end side of the discharge hole 11 in the closing direction has a strong repulsive force. Since the PTFE spring 20 is used, which has a very small decrease in strength over time due to creep or thermal creep, the check valve 12 described above is used.
The spring load value for urging the valve element 12b in the closing direction becomes large, and even when the tip opening of the discharge hole 11 of the pump is installed and used at a position lower than the suction tank, it is several times higher than the head pressure of the tank. The valve body 12b of the check valve 12 on the tip end side of the discharge hole 11 opens only when the discharge pressure of 10 is generated in the bellows 13, and at this time, the valve of the check valve 6 on the base end side of the suction hole 3 is opened. The body 6b is reliably closed and held by the pressure in the bellows 13 and opposes the head pressure of the tank. Therefore, it is possible to prevent the occurrence of the siphon phenomenon due to the valve body 6b of the check valve 6 on the base end side of the suction hole 3 being opened unexpectedly below the head pressure of the tank, and it is possible to ensure a predetermined quantitativeness. Is. Further, since the strength of the PTFE spring 12c does not decrease with time due to creep and thermal creep, it is possible to stably maintain the quantitative property even when it is repeatedly operated at a normal temperature to a high temperature of 100 ° C. Is.

Incidentally, the check valve 1 on the tip side of the discharge hole 11
As the spring 12c for elastically biasing the valve body 12b in 2 in the closing direction, the reproducibility test contents conducted by the inventor of the 5 ml / 1 shot bellows type metering pump using a conventional coil-shaped resin spring and The result will be explained. Reproduction test method and test conditions: Test piping for the reproduction test is as shown in FIG. 6, and pump operating conditions for the test are as shown in Table 3.

[0028]

[Table 3]

The results of the above-mentioned reproduction test are as shown in FIG. 8. As is clear from this test result, 5 ml / 1 s
Stroke speed is 4sp, which should be hot
30 ml or more at m and 15 ml at 10 spm
As described above, as the stroke speed is lower, the discharge amount increases due to the siphon phenomenon that occurs at the time of discharge, and the quantitativeness cannot be secured. On the other hand, the above-mentioned PT is used as the spring 12c that elastically biases the valve body 12b of the check valve 12 on the tip end side of the discharge hole 11 in the closing direction.
5 ml / 1 of the present invention using the FE spring 20
Regarding the quantitativeness of the shot bellows type metering pump, the results of the reproduction test under the same test method and test conditions as above are:
As shown in FIG. 9, as is clear from the test results, 5 ml / 1 regardless of the change in stroke speed.
It is kept almost constant with the shot, and the quantification can be secured.

The long-term test conducted by the inventor of the present invention under the same test method and test conditions as described above for the quantitative property of the 5 ml / 1 shot bellows type metering pump using the PTFE spring 20 as described above. Explain the contents and the results. Long-term test items; (a) Long-term continuous test at room temperature: With the test piping shown in FIG.
Continuous operation at 40 spm and discharge rate measurement for 4 s
Two points, pm and 40 spm. (B) Long-term continuous test at high temperature of 80 ° C .: The test pipe shown in FIG. 6 is continuously operated at 40 spm, and the discharge amount is measured at 2 points of 4 spm and 40 spm. (C) Thermal cycle long-term continuous test (normal temperature 1Hr. And 80 ° C
1 Hr. 2 Hr. One cycle of heat cycle is repeated): The test pipe shown in FIG. 6 is continuously operated at 40 spm, and the discharge amount is measured at two points of 4 spm and 40 spm. Test result; The test result of (a) is as shown in FIG. 10, the test result of (b) is as shown in FIG. 11, and the test result of (c) is as shown in FIG. As is clear from the results, in the 5 ml / 1 shot bellows type constant rate pump of the present invention using the PTFE spring 20, the discharge accuracy is 5 ml in each of the long-term tests of normal temperature, high temperature 80 ° C. and thermal cycle. Holds ± 2% and is stable. In particular, the stability increases as the number of strokes increases. On the other hand, in the conventional 5 ml / 1 shot bellows type metering pump using the coil-shaped resin spring, the repulsive force decreases to (1/3) or less in one cycle of the normal temperature to 80 ° C. thermal cycle. , (A) ~
I couldn't even get a test result to compare with the test result in (c),
It can be easily understood that the discharge amount is about 6.5 to 30 ml in one cycle.

Although PTFE is used as the constituent resin material of the resin spring 20 in the above embodiment, a fluorine resin such as PFA may be used instead.

Further, in the bellows type metering pump described in the above embodiment, the check valve 1 on the tip side of the discharge hole 11 is provided.
2 and the check valve 6 on the base end side of the suction hole 3 are both PTF.
Although the E-made spring 20 is used, even if the PTFE-made spring 20 is used only for the check valve 12 on the tip end side of the discharge hole 11, the same quantitative performance as described above can be exhibited.

[0033]

As described above, according to the invention described in claims 1 to 3, the fluororesin belt-like sheet is bent in a zigzag shape with a predetermined bulge-like curvature, and the adjacent predetermined curvatures are formed. Since it is a resin spring that is formed so that the side surfaces of the bent parts are close to or in contact with each other and that state is a free length, the curvature of each bent part that becomes large when compressive force is applied to it It is possible to generate a large repulsive force by collecting the force when trying to restore the bulge-like curvature of the, and compared with the conventional coil-shaped resin spring, the time due to fatigue and resin creep with repeated use As a result, the resin itself can have a large repulsive force and strength. Further, since each bent portion having the above-mentioned bulging curvature is elastically expandable and contractible by heating and holding and cooling while keeping the side surfaces close to or in contact with each other, it can be used even when heat is applied. It has resilience, almost no decrease in repulsive force and strength due to heat cycle, it retains its initial strength over a long period of time, and can reliably exhibit its original elastic function regardless of long-term use. Moreover, as compared with the conventional resin-covered spring, the manufacturing is simple and the cost can be significantly reduced.

Further, according to the invention described in claim 4, even when the discharge port of the pump is installed at a position lower than the suction tank, the discharge pressure in the bellows is several times higher than the head pressure of the tank. First, the valve element of the check valve on the tip side of the discharge hole is opened, and the valve element of the check valve on the base side of the suction hole is opened unexpectedly below the tank head pressure. It is possible to prevent the occurrence of the siphon phenomenon that accompanies the decrease in the spring load value regardless of the number of times the discharge is repeated at room temperature or high temperature. The effect of being able to secure a predetermined quantitativeness over the entire range is obtained.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a method of manufacturing a resin spring according to the present invention.

FIG. 2 is an enlarged side view of the manufactured resin spring.

FIG. 3 is an enlarged side view showing a state change when a compressive force is applied to the resin spring.

FIG. 4 is a vertical sectional side view of a bellows type metering pump according to the present invention.

5 is a vertical sectional front view taken along the line AA of FIG.

FIG. 6 is an explanatory view showing a test pipe for a reproduction test on a quantitative property of a bellows type metering pump.

FIG. 7 is a graph showing a correlation of stroke speed / time lag of the discharge side solenoid valve used in the same test.

FIG. 8 is a graph showing a reproduction test result of a bellows type metering pump using a conventional coil-shaped resin spring.

FIG. 9 is a graph showing the results of a reproduction test of a bellows type metering pump using the PTFE spring of the present invention.

FIG. 10 shows a long-term test of the quantification of the bellows type metering pump using the PTFE spring of the present invention.
It is a graph which shows the long-term test result in normal temperature.

FIG. 11 is a graph showing the long-term test results at 80 ° C. in the same long-term test.

FIG. 12 is a graph showing the results of a long-term test in a thermal cycle in the same long-term test.

[Explanation of symbols]

1 pump body 2 Circular protrusion 3 suction holes 4 U-shaped grooved fluid passage 6 Check valve on the suction hole side 6b, 12b valve body 6c, 12c (20) PTFE spring 11 Discharge hole 12 Check valve on the discharge hole side 13 Bellows 15 reciprocating body 16 reciprocating drive 21 PTFE strip-shaped sheet 21a Bent part L free length R bulge-like curvature

Continuation of the front page (56) Reference JP-A-8-145100 (JP, A) JP-A-3-213735 (JP, A) JP-A-5-96750 (JP, A) JP-A-63-152736 (JP , A) JP 57-63245 (JP, A) Actual Kaihei 7-7770 (JP, U) Actual Kokoku 61-10049 (JP, Y1) Special Table 1-502770 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) F16F 1/18 F04B 43/02

Claims (4)

(57) [Claims] 1. A fluororesin band-shaped sheet is bent in a zigzag shape with a predetermined bulging curvature along its longitudinal direction, and side surfaces of adjacent bent portions having a predetermined curvature are close to each other. Alternatively, it is formed so as to have a free length in a compressed state so as to come into contact with each other, and the bent portions having a predetermined curvature are elastically expandable / contractible by heating and holding and cooling, and further compress in the free length direction.
Characterized by expressing repulsive force by applying contraction force
Resin spring for check valve of metering pump . 2. The resin spring for a check valve of a metering pump according to claim 1, wherein the fluororesin is PTFE. 3. The belt-shaped sheet has a thickness of 0.05 mm to
Is 1.0 mm, and quantified according to claim 1 or 2 radius of curvature of each bent portion is 0.05mm or more
Resin spring for check valve of pump . 4. A pump body having a discharge hole for a transferred fluid formed at an end face of a circular protrusion having a suction hole for the transferred fluid and a fluid passage communicating with the suction hole. A cylindrical end, which is disposed on the outer circumference of the circular protrusion, one end of which is fixed to the pump body, and the other end closing portion of which is in contact with the end face of the distal end of the circular protrusion and the cylindrical protrusion. Provided at the base end portion of the suction hole, a bellows that expands and contracts between an extended end position separated from the end surface of the tip portion, a reciprocating drive device that is connected to the bellows to expand and contract the bellows. And a check valve for allowing the flow of the transferred fluid only in the suction direction, and a check valve provided at the tip of the discharge hole for allowing the flow of the transferred fluid only in the discharge direction. Type metering pump Of the check valve, the valve body in the check valve of at least the discharge hole side as a spring for elastically urging the closing direction,
Constant of the structure described in any one of the claims 1 to 3
A bellows type metering pump characterized by using a resin spring for a check valve of a metering pump.