Pump pulsation reducer

Abstract

To provide a pump pulsation reducer that is capable of sending liquid with reduced pulsation of discharged liquid in a region of relatively low pressure and low flow rate from a small pump while having a structure that has no movable part and is simple to use.SOLUTION: A pump pulsation reducer (1) includes: a body part (10) which is formed with a through flow passage (20); a cap part (12) which is mounted with the periphery of its drain hole (15) sealed; and a pipe member (2) which is inserted into the through flow passage and into which discharged liquid from a pump is introduced. The cap part has a first compartment (22) in which liquid (E) blown out from a tip of the pipe member is bounced back to become backflow. The through flow passage of the body part has a second compartment (25) into which a backflow (E') is introduced, a central contraction flow passage (26), a third compartment (27) and a drawing flow passage (21) which draws output liquid (E") from the third compartment.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a pump pulsation reducer that is disposed in a discharge circuit of a small pump used for liquid feeding in a relatively small flow rate and low pressure region in various research and development fields including, for example, semiconductors and pharmaceuticals, for reducing pulsation of discharged liquid.

Background Art

[0002] In the manufacturing processes of various products, in many cases, the supply of various liquids depends on pumps, and there are pumps of various scales and types. Among them, in the case of a plunger pump or a diaphragm pump, due to its principle and structure, it is inevitable that the discharged liquid from the pump pulsates. Therefore, a method for reducing pump pulsation has been conventionally considered for stable quantitative liquid feeding.

[0003] For example, in many cases, an accumulator or a similar pressure accumulator as disclosed in Patent Documents 1 and 2 is disposed in the discharge flow path of the pump. The pulsation is attenuated by utilizing the action of storing the working fluid at high pressure and discharging it at low pressure in these accumulators and pressure accumulators.

[0004] A general accumulator stores gas in a chamber (bladder) formed by an elastic membrane inside a container. When the pressure in the pump circuit is higher than the enclosed pressure of the stored gas, the stored gas is compressed through the bladder and the working fluid is accumulated in the container. When the pressure in the circuit decreases, the stored gas expands and discharges the working fluid. However, since it is necessary to finely adjust the accumulator gas pressure etc. if the magnitude of pulsation, discharge pressure / flow rate etc. are different, it takes complicated labor and time for preparation.

[0005] In addition, there is also one that depends on valve movement, such as a pulsation reduction device that suppresses pressure fluctuations by displacing the cross-sectional area of a flow path by moving a valve body disposed in the flow path disclosed in Patent Document 3 via a spring.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2022-111116 [Patent Document 2] Japanese Patent No. 6575487 [Patent Document 3] Japanese Patent Application Laid-Open No. 2015-108295 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] However, the conventional accumulator type or valve movable type pulsation reduction methods as described above are targeted at high discharge pressures by relatively large pumps such as hydraulic pumps that supply highly viscous hydraulic oil or fuel supply pumps in internal combustion engines. In particular, in the small flow rate range of 100 ml / min or less, it is a reality that they hardly function.

[0008] On the other hand, there are many cases where it is desired to quantitatively supply a small flow rate of liquid as described above at a low pressure of several to several tens of Mpa by a relatively small pump. For example, in the production tests of pharmaceuticals, cosmetics, and other various research and development compounds, when continuously supplying a small amount of low-viscosity liquids such as water, solvents, and chemical solutions to a reactor during a synthesis reaction, a small pump that can be used on a desktop is used, but stable liquid delivery at a constant flow rate with suppressed pulsation is required. Also, in the semiconductor manufacturing process, for example, in a single-wafer cleaning apparatus, various cleaning chemical solutions are sprayed onto the wafer surface by nozzles (spray type), and continuous chemical solution supply with suppressed pulsation to the nozzles is desired.

[0009] As a mechanism for suppressing pump pulsation when transferring such low-viscosity liquids in small amounts and at low pressures, a static configuration without a movable part and without the need for accumulator gas is desired, but an appropriate one has not yet been realized.

[0010] In view of the above problems, an object of the present invention is to provide a pump pulsation reducer that does not require an accumulator gas and a movable part, is easy to use, and can reduce the pulsation of the discharged liquid in a relatively low-pressure and small-flow rate region from a small pump and deliver the liquid.

Means for Solving the Problems

[0011] In order to achieve the above object, the pump pulsation reducer according to the invention described in claim 1 is arranged in the discharge flow path of the pump, for example, as shown in FIGS. 1, 4, 5, 6, and 7, introduces the liquid discharged from the pump, and reduces and discharges the pulsation of the liquid. It is a pump pulsation reducer, A main body part having an inlet for the liquid opened on one end face, an outlet for discharging the liquid introduced from the inlet opened on the other end face opposite to the one end face, and a through-flow path formed from the inlet to the outlet; and a cap part attached to the other end face of the main body part and sealing the periphery of the outlet. The cap part has a first partition chamber formed of a cylindrical laterally concave part for receiving the liquid discharged from the main body part coaxially with the central axis of the through-flow path. The main body part Comprises a pipe member inserted throughout the interior of the through-flow path and hermetically held coaxially with the central axis at the inlet. The pipe member has its pipe rear end connected to the discharge flow path of the pump, and its pipe front end protrudes from the outlet into the interior of the first partition chamber to an interval position where the liquid can be ejected and collided against the abutting end face of the first partition chamber. The through-flow path A cylindrical second partition chamber for receiving the backflow of the fluid ejected from the pipe front end and rebounded from the first partition chamber between the outer peripheral surface of the pipe member; An intermediate throttle flow path formed in the middle of the through-flow path, having a reduced diameter and communicating at the rear end of the second partition chamber, and receiving the backflow from the second partition chamber as a throttled flow; The rear end of the intermediate throttle passage is enlarged in diameter and communicates therewith, and a cylindrical third partition chamber that diffuses the contracted flow from the intermediate throttle passage and has the inlet formed at its rear end is formed coaxially so as to be able to insert the pipe member therethrough. It is characterized by further comprising a discharge passage that communicates with the third partition chamber, branches from the through passage, and has an outlet for the liquid opened on the outer peripheral surface of the main body portion.

[0012] According to the pump pulsation reducer according to claim 1 of the present invention, the discharge liquid from the pump introduced into the pipe member inserted coaxially into the through passage of the main body portion is ejected from the tip of the pipe member protruding from the discharge port on one end surface of the main body portion, collides with the inner wall surface of the first partition chamber of the cap portion, bounces back and becomes a reverse flow, and flows in the outer peripheral region of the pipe member in the through passage. Here, in the pump pulsation reducer of the present invention, the advancing direction (forward flow) of the liquid flowing inside the pipe member is taken as the front, and the reverse flow direction is taken as the rear.

[0013] In the present invention, first, the energy of the liquid flow is reduced by the reversal of the flow due to the bounce in the first partition chamber. The reverse flow bounced back in the first partition chamber also has its flow velocity rapidly decreased. This reverse flow returns from the discharge port to the main body portion side, is introduced into the second partition chamber, and advances in the opposite direction to the inside of the pipe member in the outer peripheral region of the pipe member. At this time, it collides with the inner wall surface of the second partition chamber and advances while the energy is reduced, and then collides with the periphery of the opening of the intermediate throttle passage at the rear end wall surface and is introduced into the intermediate throttle passage as a contracted flow.

[0014] The reverse flow introduced into the intermediate throttle passage advances while colliding with the inner wall surface and the outer peripheral surface of the pipe member in the outer peripheral region of the pipe member, and the energy is reduced. Then, the reverse flow that has passed through this intermediate throttle passage is introduced into the third partition chamber. The reverse flow introduced into the third partition chamber has its pulsation considerably suppressed at this point, is stabilized here, and is output from the discharge passage in a state where the pulsation is greatly reduced.

[0015] Therefore, according to the pump pulsation reducer of the present invention, without using accumulator gas or providing a moving part, while having a static configuration, due to its internal flow path configuration, the flow of the liquid discharged from the target pump is reversed to cause a backflow, and the backflow is repeatedly collided with and an orifice effect is given to reduce the energy of the fluid, so that the liquid can be sent from the outlet flow path in a state where the pulsation is greatly reduced. Moreover, the pump pulsation reducer of the present invention can be easily used by simply arranging it in the discharge flow path of the pump.

[0016] The pulsation reduction effect utilizing the collision and orifice effect in the present invention is particularly well exhibited in pumps that discharge a relatively small flow rate of low-viscosity liquids including water, organic solvents, etc. at low pressure. For example, in a small pump with a rated pressure of 10 to 40 MPa and a rated flow rate of about 100 mL / min to 5 L / min, the pulsation reduction effect according to the present invention at a very small flow rate of 1 mL / min to 20 mL / min can be confirmed in the examples described later.

[0017] In the main body of the pump pulsation reducer of the present invention, as a mechanism for coaxially holding the pipe member in the through-flow path, it is sufficient to simply use a biting joint that screws into the inlet of the main body. By using a nut-double (front / back) ferrule type as this biting joint, high watertightness can be ensured at the same time.

[0018] As a means for sealing the periphery of the discharge port when the cap part is attached to the main body part in the present invention, a configuration using an O-ring is simple. Specifically, if a groove with a predetermined width is formed around the discharge port of the main body part and the O-ring is fitted into the groove, the end face of the cap part will be in close contact with the O-ring on the groove during attachment, and the outer peripheral region of the discharge port will be watertight.

[0019] Also, for the attachment and fixation of the main body part and the cap part, a bolt member that penetrates and fastens both is simple. In this case, female screw holes that penetrate through the cap part and the main body part may be provided at positions concentric with the central axis of the through-flow path and having a predetermined angular interval with respect to each other in the outer peripheral region from the groove and O-ring around the discharge port.

[0020] Furthermore, as the material of the constituent members of the pump pulsation reducer according to the present invention, any material with sufficient mechanical strength and corrosion resistance used in general injection nozzles or the like can be adopted. Examples include metals such as stainless steel (SUS) and brass, or ceramics, resin-molded ceramics, and the like. Furthermore, Hastelloy, which is a special alloy with excellent corrosion resistance, tantalum, titanium, etc. can also be adopted, and it is not particularly limited.

[0021] In addition, since the intermediate throttle passage is integrally formed in the main body portion, mechanical strength and workability are required at the same time. Therefore, it is more preferable to use austenitic stainless steel with excellent ductility and toughness as the material. Representative examples include SUS303, SUS304, and SUS316. Among them, in the pump pulsation reducer according to the present invention, since the use of various solvents is considered, SUS316 or SUS316L (low carbon), which is more excellent in corrosion resistance, is the most suitable material.

[0022] The pump pulsation reducer according to the invention described in claim 2 further includes, for example, as shown in FIGS. 1, 5, and 6, a throttle member that is fitted into the discharge port of the main body portion and sends the backflow from the first partition chamber to the second partition chamber. The throttle member is characterized in that it has a reduced diameter and communicates in front of the second partition chamber, forming a front throttle passage through which the pipe member is inserted.

[0023] According to the pump pulsation reducer described in claim 2 according to the present invention, a front throttle passage with a reduced diameter is added in front of the second partition chamber by the throttle member fitted into the discharge port of the main body portion. For this reason, the backflow from the first partition chamber is first introduced into this front throttle passage, where it collides repeatedly between the inner wall surface of the front throttle passage and the outer peripheral surface of the pipe member and with each other, and the energy is reduced before being sent to the second partition chamber. Therefore, a further pulsation reduction effect is exerted by the orifice effect of the added front throttle passage.

[0024] The pump pulsation reducer according to the invention of claim 3, for example, as shown in FIGS. 1, 5, and 6, the throttle member has a base portion that is fitted and fixed to the discharge port at its outer peripheral portion, and a tubular portion that extends forward from the base portion and protrudes into the interior of the first partition chamber, and the hollow portion thereof serves as the forward throttle flow path. The base portion is characterized in that a tapered portion is formed that continuously increases in diameter in the rear end region of the forward throttle flow path and radially diffuses the backflow from the forward throttle flow path to the second partition chamber.

[0025] According to the pump pulsation reducer of claim 3 according to the present invention, since the forward throttle flow path is formed by the hollow portion of the tubular portion that protrudes into the first partition chamber of the throttle member, this tubular portion serves as a return conduit to receive the backflow. And also in the outer peripheral region of this tubular portion, fluid collisions are repeated between the inner wall surface of the first partition chamber, and an energy reduction effect is exerted to contribute to the reduction of pulsation.

[0026] The backflow that has advanced while repeating collisions in the forward throttle flow path in this way is radially diffused into the second partition chamber along the tapered portion of the base portion. As a result, the backflow introduced into the second partition chamber increases in its flow velocity and also collides well with the inner wall of the second partition chamber, so that the energy is further reduced.

[0027] In addition, if the distance D between the pipe tip of the pipe member and the abutting end surface of the first partition chamber facing it becomes too small, the pressure loss here becomes large, and the overall total dynamic pressure loss in the pump pulsation reducer also becomes too large. Also, if the distance D becomes too large, a sufficient nozzle effect cannot be obtained to reverse the flow of the liquid.

[0028] Therefore, the distance D may be determined to be a ratio to the inner diameter I of the pipe member such that an appropriate backflow at an appropriate speed can be obtained by appropriate collisions and rebounds in consideration of the viscosity of the liquid that is actually the supply target. For example, an injection collision test can be performed around about 80% of the inner diameter I of the pipe member, and based on the results, an appropriate distance D can be finally determined.

[0029] Further, in the pump pulsation reducer of the present invention, regarding the intermediate throttle passage and the forward throttle passage, the smaller the inner diameter F of each throttle passage and the narrower the flow passage area of the outer peripheral region of the pipe member, the higher the reverse flow velocity can be increased. However, if it is extremely narrowed, the pressure loss becomes too large and an appropriate reverse flow cannot be obtained. On the other hand, if the inner diameter F is too large, a good orifice effect cannot be obtained and an appropriate flow velocity cannot be ensured.

[0030] Therefore, the inner diameter F of these throttle passages may be set based on the design dimensions of the pipe member actually incorporated so that the flow passage area of the outer peripheral region of the pipe member can suppress the pressure loss while maintaining a high flow velocity. For example, the inner diameter F of each throttle passage is centered on the dimension when the area of the inner cross-section of the outer peripheral region of the pipe member coincides with the inner cross-sectional area of the pipe member, and is appropriately determined to be suitable in consideration of the permanent pressure loss that varies depending on the viscosity of the actual supply liquid.

[0031] Also, the lengths of the forward throttle passage and the intermediate throttle passage are appropriately determined according to the mechanical strength of the constituent members and the requirements from the processing technology. On the other hand, a pipe member with a pipe size suitable for the introduced flow rate range is selected.

[0032] In addition, since the internal volumes of the first, second, and third partition chambers occupy almost all of the total internal volume of the pump pulsation reducer according to the present invention, they are determined according to the flow rate range. Practically, it is desirable to confirm and determine the threshold point at which the total internal volume of this pump pulsation reducer can be further reduced with reference to 1 / 10 to 1 / 15 of the rated flow rate of the target pump based on water. Also, the inner diameter and length dimensions of each partition chamber are finally determined in consideration of the mechanical strength of the constituent members, the processing technology, and the cost.

Advantages of the Invention

[0033] According to the pump pulsation reducer of the present invention, as described above, it has a static configuration that does not require accumulator gas and movable parts, and by utilizing the bounce-back reversal of the flow path and the orifice effect, it is possible to effectively reduce the pulsation of the discharged liquid with a relatively low pressure and a small flow rate from a small pump, which was difficult in the past.

Brief Description of the Drawings

[0034]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Figure 10

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Figure 12

Figure 13

Mode for Carrying Out the Invention

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0036] <Embodiment> FIGS. 1 to 3 show an embodiment of the pump pulsation reducer according to the present invention. As shown in FIG. 1, the pump pulsation reducer 1 in this embodiment has an inlet 14 for introducing the discharged liquid from the target pump opened on one end face, an outlet 15 for discharging the liquid opened on the other end face opposite thereto, and a main body portion 10 in which a through-flow path 20 extending from the inlet 14 to the outlet 15 is formed, and a cap portion 12 attached to the other end face of the main body portion 10 for sealing the periphery of the outlet 15.

[0037] The cap portion 12 has a first partition chamber 22 formed by a cylindrical lateral recess for receiving the liquid discharged from the discharge port 15. Further, in the main body portion 10, a discharge flow path 21 is formed which branches from the through-flow path 20, extends in a direction orthogonal to the central axis X of the through-flow path 20, and opens a liquid discharge port 19 on the outer peripheral surface of the main body portion 10.

[0038] In the main body portion 10, a pipe member 2 connected to the discharge flow path of the target pump and into which fluid is introduced is inserted into the through-flow path 20 with both ends protruding therefrom. This pipe member 2 is coaxially and hermetically held with the through-flow path 20 by an engaging joint 3 that is screwed and fixed to the female screw portion formed at the inlet 14 at the rear end of the pipe. In this embodiment, a high level of watertightness is ensured by using a nut double (front / back) ferrule type as the engaging joint 3. Also, the pipe member 2 is positioned such that the tip of the pipe protrudes into the first partition chamber 22.

[0039] The through-flow path 20 includes a cylindrical second partition chamber 25 that receives the backflow of the liquid ejected from the pipe tip and rebounded from the first partition chamber 22 between the outer peripheral surface of the pipe member 2, an intermediate throttle flow path 26 that is formed in the middle of the through-flow path 20, communicates with the rear end of the second partition chamber 25 with a reduced diameter, and receives the backflow from the second partition chamber 25 as a throttled flow, and a cylindrical third partition chamber 27 that communicates with the rear end of the intermediate throttle flow path 26 with an increased diameter, diffuses the throttled flow from the intermediate throttle flow path 26, and has an inlet 14 formed at its rear end. These are coaxially formed so that the pipe member 2 can be inserted therethrough. The discharge flow path 21 is provided in communication with the third partition chamber 27.

[0040] Also, in this embodiment, a throttle member 30 having a flow path for communicating with the front of the through-flow path 20 at the discharge port 15 of the main body portion 10 and sending the backflow from the first partition chamber 22 to the second partition chamber 25 is fitted. Accordingly, the cap portion 12 is integrally attached to the main body portion 10 with the throttle member 30 fitted into the discharge port 15. Here, the main body portion 10 and the cap portion 12 integrally attached thereto form one outer shape.

[0041] In this embodiment, the main body 10 has a substantially cylindrical shape coaxial with the central axis X of the through-flow path 20, which is an outer shape that is easy to handle. Further, in this embodiment, the lower part of the cylindrical outer shape of the main body 10 is the bottom surface 11 of the notch, and the cap part 12 is also formed with a bottom surface 13 of a notch having a cylindrical outer shape that is flush with the bottom surface 11 when attached to the main body 10. These bottom surfaces (11, 13) serve as the installation surface of the pump pulsation reducer 1. Of course, the pump pulsation reducer 1 is not limited to such a cylindrical outer shape, and can have various outer shapes such as, for example, a quadrangular prism or a polygonal prism.

[0042] In this embodiment, a groove 16 is formed on the outer peripheral side concentric circle of the discharge port 15 on one end surface of the main body 10, and an O-ring 6 is fitted into this groove 16. As a result, when the cap part 12 is attached to the main body 10, the end surface of the cap part 12 is in close contact with the O-ring 6 on the groove 16, and the discharge port 15 is sealed in its outer peripheral region.

[0043] The integral attachment of the main body 10 and the cap part 12 is by screw fastening. Therefore, female screw holes (17, 18) into which a bolt member 5 for screw-fastening the two is screwed are provided so as to penetrate both the cap part 12 and the main body 10. In this embodiment, as shown in FIGS. 2 and 3, four upper, lower, left, and right positions that coincide with each other on the same concentric circle around the center axis X of the outer peripheral region of the groove 16·O-ring 6 of the main body 10 and the outer peripheral region of the first partition chamber 22 of the cap part 12 in a front view are used as screw fastening parts. Here, it is assumed that the upper and lower screw fastening parts have an angular interval of 60°.

[0044] The throttle member 30 is fitted to the discharge port 15 of the main body 10 at the outer peripheral part of its base 31, and a tubular part 32 extends forward from the base 31. In the state where the cap part 12 is attached to the main body 10, this tubular part 32 protrudes into the first partition chamber 22, and its hollow part forms a forward throttle flow path 24 that communicates with a reduced diameter in front of the second partition chamber 25.

[0045] Therefore, the pipe member 2 is coaxially inserted throughout the entire through-flow path 20 including the second partition chamber 25, the intermediate throttle flow path 26, and the third partition chamber 27, and is further inserted into the forward throttle flow path 24 of the throttle member 30. Then, the pipe tip is positioned at an interval D at which the liquid introduced against the abutting end surface 23 of the first partition chamber 22 can be ejected and collided, and is held in this state. Therefore, the outer peripheral region of the pipe member 2 in the forward throttle flow path 24 and the through-flow path 20 becomes a substantial return flow path through which the backflow of the pump discharge liquid flows.

[0046] Also, in the present embodiment, the throttle member 30 is provided with a tapered portion 33 that expands in diameter from the rear end of the forward throttle flow path 24 at the base portion 31. Therefore, the backflow introduced from the first partition chamber 22 into the forward throttle flow path 24 is radially diffused into the second partition chamber 25 by the tapered portion 33.

[0047] The discharge flow path 21 that communicates with the third partition chamber 27 and discharges the liquid branches and extends in a direction orthogonal to the central axis X of the through-flow path 20, and opens a discharge port 19 on the outer peripheral surface of the main body portion 10. In the present embodiment, a female thread portion is formed in the discharge port 19, and the bite joint 4 is screwed and fixed to this female thread portion. Through this bite joint 4, the discharge flow path 16 is connected to a pipe or the like that communicates with the transfer destination of the liquid with reduced pulsation.

[0048] In addition, in the present embodiment, the main body portion 10, the cap portion 12, the throttle member 30, the bolt member 5, and the pipe member 2 are all manufactured using the same material, SUS316 or SUS316L.

[0049] The pump pulsation reducer according to the present embodiment is designed for small pumps with a rated pressure of 10 to 40 MPa and a rated flow rate of about 100 to 500 mL / min. In particular, it enables pulsation reduction at an extremely small flow rate of 100 mL / min or less, which was conventionally impossible to handle. Also, by appropriately adjusting the design of each part, it can be made adaptable to pumps with a rated capacity of up to 5 L / min.

[0050] The pipe member 2 is selected to have a pipe size suitable for the introduced flow rate range. For example, for a flow rate range of up to 500 mL / min (water-based), a pipe type (1) with an outer diameter (OD) of 1 / 8” and a thickness t = 0.8 mm made of SUS316 is suitable. Also, for a larger flow rate range of up to 2 L / min (water-based), a pipe type (2) with an outer diameter (OD) of 1 / 4” and a thickness t = 1.00 mm made of SUS316 is suitable. Further, for different flow rate ranges, other pipe sizes suitable accordingly can be selected.

[0051] Therefore, when manufacturing the pump pulsation damper 1, when the forward throttle passage 24 and the intermediate throttle passage 26 are formed, the inner diameter F of a dimension appropriately larger than the pipe diameter is set and processed according to the pipe size of the pipe member 2 to be incorporated in advance.

[0052] Also, the internal volumes of the first partition chamber 22, the second partition chamber 25, and the third partition chamber 27 are determined by the flow rate range in which the liquid is actually delivered because they occupy almost all of the total internal volume of the pump pulsation damper 1. In this embodiment, as the total internal volume of the pump pulsation damper 1, 1 / 10 to 1 / 15 of the rated flow rate of the target pump in water-based is used as a guide, and the threshold point is confirmed and determined so as to be as small as possible.

[0053] In actual verification, it was found that a total internal volume of 8 to 10 mL is appropriate in the case of a rated flow rate of 100 mL / min (water-based). The inner diameters and length dimensions of the first partition chamber 22, the second partition chamber 25, and the third partition chamber 27 are determined based on the set appropriate total internal volume, considering the mechanical strength, processing technology, and cost.

[0054] In the pump pulsation reducer 1 according to the present embodiment having the above-described configuration, the pump pulsation is reduced along the following flow. First, when the liquid E discharged from a target pump (not shown) is introduced as a forward flow into the rear end of the pipe member 2 inserted and held in the through-flow path 20 of the main body portion 10 of the pump pulsation reducer 1, the liquid E advances in the pipe member 2 and is ejected forward from the pipe tip as shown in FIG. 4.

[0055] Then, the liquid E ejected from the pipe tip collides with the abutting end face 23 of the first partition chamber 22 of the cap portion 12 and bounces back, reversing the flow path. The bounced-back liquid further collides with the inner wall surface around the abutting end face 23 within the first partition chamber 22, reducing the energy of the liquid flow and rapidly reducing the flow velocity. As a reverse flow E', it flows into the forward throttling flow path 24 formed by the tubular portion 32 of the throttle member 30, which is a return conduit.

[0056] The reverse flow E' that has flowed into the forward throttling flow path 24, as shown in FIG. 5, advances backward in the outer peripheral region of the pipe member 2 in the direction opposite to the inside of the pipe member 2, while repeatedly colliding between the inner wall surface of the forward throttling flow path 24 and the outer peripheral surface of the pipe member 2 and colliding with each other, thereby further reducing the energy.

[0057] The reverse flow E' that has passed through the forward throttling flow path 24 is radially diffused into the second partition chamber 25 along the tapered portion 33 as shown in FIG. 6, increasing its flow velocity further and reducing the energy more. Then, the reverse flow E' introduced into the second partition chamber 25 also collides with the inner wall surface of the second partition chamber 25 in the outer peripheral region of the pipe member 2 and advances while reducing the energy, and after colliding with the periphery of the opening of the intermediate throttling flow path 26 at the rear end wall surface 25b, it is introduced into the intermediate throttling flow path 26 as a constricted flow.

[0058] The reverse flow E' introduced into the intermediate throttle passage 26 advances while colliding between the inner wall surface and the outer peripheral surface of the pipe member 2 in the outer peripheral region of the pipe member 2, and the energy is reduced at a wavelength different from the energy reduction in the forward throttle passage 24. Then, as shown in FIG. 7, the reverse flow E' that has passed through the intermediate throttle passage 26 is introduced into the third partition chamber 27. The reverse flow E' introduced into the third partition chamber 27 has its pulsation considerably reduced at this point, and is stabilized here and output from the outlet passage 21. The output liquid E'' is stably transferred to the target position with almost all of the initial pulsation removed.

Example

[0059] As an example of the present invention, an evaluation test of the pulsation reduction effect by the pump pulsation reducer 1 in FIG. 1 was conducted. Specifically, in the pump fluid circuit, the output flow rate of the pumped water is measured to obtain data on the flow rate amplitude corresponding to the pulsation, and the difference in the amplitude is compared with or without the pump pulsation reducer. The results of data acquisition for different pump set flow rates are shown in the graphs of FIGS. 8 to 12.

[0060] In this example, as the pump pulsation reducer 1, a pipe member 2 made of SUS316 of tube type (1) with an outer diameter of 1 / 8" OD (outer diameter 1 / 8 inch) and a thickness t = 0.8 mm was incorporated, and the evaluation test was conducted as follows with the total internal volume designed to be 8 to 10 mL.

[0061] In this example, as Test 1, data on the basic amplitude was obtained with the pump set flow rate set to 0 mL / min, and the results are shown in FIG. 8. Further, when the pump set flow rates are 1 mL / min, 5 mL / min, 10 mL / min, and 20 mL / min, the results are shown in FIGS. 9, 10, 11, and 12 as Tests 2, 3, 4, and 5, respectively.

[0062] The test conditions were as follows: As the pump, a double plunger pump NP-KX (FS: free scale 20 mL / min) manufactured by Nippon Precision Science Co., Ltd. was used to construct a fluid circuit. A Coriolis flowmeter M13 (FS 100 mL / min, accuracy ±0.2% reading) manufactured by Bronkhorst Japan Co., Ltd. was connected to the output side of the fluid circuit, and flow rate measurement was performed over time.

[0063] In this test, the electrical noise filter was removed during flow rate measurement. The data acquisition period was set to 50 ms, and the displacement percentage with respect to the set flow rate based on the measured value of the output flow rate was acquired as data. The graph showing the results of each test has the elapsed time (one scale: 2 seconds) on the horizontal axis, and on the vertical axis, the data of the ratio of the displacement amount (one scale: 1%) with respect to the set flow rate (one scale: 1 mL / min) based on the measured value by the Coriolis flowmeter is represented as the amplitude corresponding to the pulsation in a line graph.

[0064] For each pump set flow rate in Tests 1 to 5, when the pump pulsation reducer 1 was not arranged in the pump discharge side flow path, it was used as a control fluid circuit, and flow rate measurement was performed by a Coriolis flowmeter on the output side of the control fluid circuit. When the pump pulsation reducer 1 was arranged in the pump discharge side flow path, it was used as a fluid circuit with a pulsation reducer, and flow rate measurement was performed by a Coriolis flowmeter on the output side (downstream side of the pump pulsation reducer 1) of the fluid circuit with the pulsation reducer.

[0065] Then, the displacement percentage with respect to the set flow rate was acquired as data based on each measured value, and a line graph of the amplitude was obtained by representing the acquired data on the vertical axis with respect to the elapsed time (s) on the horizontal axis. By comparing these line graphs, the pulsation reduction effect of the pump pulsation reducer 1 was evaluated.

[0066] Furthermore, in each of Tests 1 to 5, data was also obtained for the case where flow rate feedback control of the pump was performed based on the measured values from the Coriolis flowmeter using a fluid circuit with a pulsation reducer, and a line graph diagram based on the amplitude was also obtained. In this feedback control, the drive of the pump motor is controlled by a control circuit (equipped with a 24V power supply and a V / A converter) consisting of a pump driver to adjust the flow rate. The evaluation results at each set flow rate of the target pump are as follows.

[0067] <Test 1> First, as Test 1, the results of obtaining data with a set flow rate of 0 mL / min for the basic amplitude are shown in Fig. 8. Here, there was almost no change between the case of the control fluid circuit (graph Fig. 8(a)) and the case of the fluid circuit with a pulsation reducer (graph Fig. 8(b)), and a noise situation with an amplitude of ±0.4% was observed in both cases. Also, when flow rate feedback control was performed on the pump based on the fluid circuit with a pulsation reducer (graph Fig. 8(c)), an amplitude of ±0.5% was observed. This is presumably because the noise amplitude increased slightly due to the increase in the mounted electronic devices.

[0068] The amplitude observed in this Test 1 is noise generated not only from electrical noise but also because the liquid cannot be completely stationary due to its transfer. This noise further includes that caused by the flowmeter error of ±0.2%RD.

[0069] <Test 2> Next, the results of obtaining data for Test 2 with a set flow rate of 1 mL / min are shown in Fig. 9. In graph Fig. 9(a) for the case of the control fluid circuit without the pump pulsation reducer 1, a larger peak appeared on the + side, and an amplitude showing a peak of up to about 0.8% was observed. In contrast, in graph Fig. 9(b) for the case of the fluid circuit with a pulsation reducer, the amplitude was reduced to about the basic amplitude in Test 1, indicating that the pulsation was suppressed.

[0070] Fig. 9(c) shows the case where flow rate feedback control for the pump is performed based on a fluid circuit with a pulsation reducer. Here, since the controllable range was 1:10, data was acquired with a set flow rate of 2 mL / min. Also, the feedback signal S is shown above the graph. In this case, although the amplitude is slightly larger compared to Fig. 9(b), this is presumably because the amplitude at the zero point has been fed back. In any case, it was shown that at the minimum flow rate of 1 - 2 mL / min, the amplitude was suppressed by the pump pulsation reducer 1 and the pulsation was almost eliminated.

[0071] <Test 3> Next, Fig. 10 shows the results of acquiring data for Test 3 with a set flow rate of 5 mL / min. In the case of the control fluid circuit without the pump pulsation reducer 1, as shown in Fig. 10(a), a larger peak appears on the + side, and there is a pulsation with an amplitude having a peak of about 2.8% at most. In contrast, in the graph of Fig. 10(b) for the fluid circuit with a pulsation reducer, the amplitude has become as small as the basic amplitude in Test 1, indicating that the pulsation is suppressed. However, it was slightly off to the + side from the set flow rate overall.

[0072] On the other hand, in the graph of Fig. 10(c) when further flow rate feedback control of the pump is performed, not only is the magnitude of the amplitude similarly suppressed to about the basic amplitude, but the amplitude is centered around the set flow rate of 5 mL / min. That is, in the case of a very low flow rate of 5 mL / min as the set flow rate, the amplitude is suppressed small by the pump pulsation reducer 1, and it was confirmed that the pulsation reduction effect by the pump pulsation reducer 1 is sufficiently exerted even for a pump with flow rate feedback control.

[0073] <Test 4> Next, the results of acquiring data for Test 4 with a set flow rate of 10 mL / min are shown in FIG. 11. In the case of the control fluid circuit without the pump pulsation damper 1, as shown in FIG. 11(a), an amplitude with peaks appearing more frequently and larger than in the case of FIG. 10(a) was observed. Here too, larger peaks appeared on the + side, and relatively large pulsations were seen, with an amplitude having peaks of up to about 4%. In contrast, in the graph of FIG. 11(b) for the fluid circuit with a pulsation damper, the amplitude was reduced to about the basic amplitude in Test 1, indicating that the pulsations were well suppressed. However, overall, it was slightly off to the + side from the set flow rate.

[0074] However, in the graph of FIG. 11(c) when further pump flow rate feedback control was performed, while suppressing the amplitude size to about the basic amplitude in the same manner, the amplitude was centered around the set flow rate of 10 mL / min. That is, at a small flow rate of 10 mL / min of the set flow rate, the amplitude was suppressed small by the pump pulsation damper 1, and it was confirmed that the pulsation reduction effect by the pump pulsation damper 1 was sufficiently exerted even for a pump with flow rate feedback control.

[0075] <Test 5> Next, the results of acquiring data for Test 5 with a set flow rate of 20 mL / min are shown in FIG. 12. In the case of the control fluid circuit without the pump pulsation damper 1, as shown in FIG. 12(a), an amplitude with larger peaks appearing at a narrower interval than in the case of FIG. 11(a) was observed. Here too, larger peaks appeared on the + side, and intense pulsations were seen, with an intense amplitude having peaks of up to about 4.3%. In contrast, in the graph of FIG. 12(b) for the fluid circuit with a pulsation damper, the large and intense amplitude was reduced to about the basic amplitude in Test 1, indicating that the pulsations were well suppressed. However, overall, it was slightly off to the + side from the set flow rate.

[0076] However, in the graph diagram 12(c) when further performing the flow rate feedback control of the pump, while suppressing the magnitude of the amplitude to about the basic amplitude in the same manner, the amplitude was centered around the set flow rate of 20 mL / min. That is, at the flow rate of 20 mL / min, very intense pulsations were significantly suppressed by the pump pulsation reducer 1. It was confirmed that the pulsation reduction effect by the pump pulsation reducer 1 is sufficiently exerted even in a pump where flow rate feedback control is performed.

[0077] <Overall test> As the overall test results in the above Tests 1 to 5, the acquired data of Tests 1 to 5 shown in FIGS. 8 to 12 were continuously plotted with the elapsed time (one scale is 10 seconds) on the horizontal axis and summarized in FIG. 13. FIG. 13(a) is a line graph showing the amplitude corresponding to the pulsation in the control fluid circuit without arranging the pump pulsation reducer in the pump discharge side flow path, and FIG. 13(b) is a line graph showing the amplitude corresponding to the pulsation in the fluid circuit with the pulsation reducer in which the pump pulsation reducer 1 is arranged in the discharge path of the pump.

[0078] As is clear from FIGS. 13(a) and (b), in this embodiment, in the very small flow rate range of 1 to 20 mL / min, a sufficient pulsation reduction effect by the pump pulsation reducer 1 was confirmed.

[0079] In the above embodiment, according to the pump pulsation reducer of the present invention, for a small pump with a rated capacity of 100 mL / min based on water, in the very small flow rate range of 1 to 20 mL / min, it was confirmed that an excellent pulsation reduction effect is exerted. Therefore, for pumps with larger rated capacities, such as 2 L / min and further 5 L / min, in a flow rate range larger than the above, by appropriately adjusting the pipe size of the pipe member in which the pump pulsation reducer is incorporated and the design dimensions of each part, a good pulsation reduction effect can be expected.

[0080] In the above embodiments, in addition to the central throttle passage of the main body through-passage, a front throttle passage is further arranged by the throttle member, and an example in which a very excellent pulsation reduction effect is exhibited by two orifice effects has been shown. However, the present invention is not limited to this. That is, even as a simpler flow path design with only one orifice effect by the central throttle passage without using the throttle member, to some extent, a pulsation reduction effect can be obtained by the combination of the rebounding and reversing of the fluid and the collision effect, and thus it may be sufficient depending on the flow rate range and the degree of pulsation of the target pump. Therefore, it is possible to appropriately select a flow rate design corresponding to the pulsation reduction effect according to the target pump conditions.

Explanation of Signs

[0081] 1: Pump pulsation reducer 2: Pipe member I: Inner diameter of the pipe member 3: Engaging joint 4: Engaging joint 5: Bolt member 6: O-ring 10: Main body part 11: Bottom surface 12: Cap part 13: Bottom surface 14: Inlet 15: Outlet 16: Groove 17: Female screw hole 18: Female screw hole 19: Outlet 20: Through-passage X: Central axis 21: Outlet passage 22: First partition chamber 23: Contact end face D: Interval (from the pipe tip to the contact end face) 24: Front throttle passage 25: Second partition chamber 25b: Rear end wall surface 26: Intermediate throttle passage 27: Third partition chamber F: Inner diameter of the front throttle passage and the intermediate two throttle passages 30: Throttle member 31: Base 32: Tubular part 33: Tapered part E: Liquid (flowing forward) E’: Reverse flow E”: Output liquid

Claims

1. A pump pulsation reducer that is disposed in a discharge flow path of a pump, introduces liquid discharged from the pump, reduces pulsations of the liquid, and discharges the liquid, a main body portion having an inlet for the liquid opened at one end surface, an outlet for discharging the liquid introduced from the inlet opened at another end surface opposite to the one end surface, and a through flow path formed from the inlet to the outlet, and a cap portion attached to the other end surface of the main body portion to seal the periphery of the outlet, the cap portion has a first partition chamber formed of a cylindrical horizontal recess that receives the liquid discharged from the main body portion and that is coaxial with a central axis of the through-flow passage, The main body portion is a pipe member inserted into the through-flow passage over its entire length and held coaxially with the central axis at the inlet, a rear end of the pipe member is connected to a discharge flow path of the pump, and a front end of the pipe member projects from the discharge port into the first compartment to a distance position where the liquid can be ejected and collided with an end face of the first compartment, The through-flow passage is a cylindrical second compartment that receives, between the outer circumferential surface of the pipe member and the first compartment, a backflow of the fluid that is ejected from the tip of the pipe and bounced back from the first compartment; a cylindrical intermediate throttle flow path formed midway through the through flow path, the diameter of which is reduced at a rear end of the second compartment chamber to communicate with the second compartment chamber, and the intermediate throttle flow path receives the backflow from the second compartment chamber as a contracted flow; a cylindrical third compartment that is expanded in diameter at a rear end of the intermediate throttle passage to communicate with the intermediate throttle passage, that diffuses the contracted flow from the intermediate throttle passage, and that has the inlet formed at its rear end, and that is formed so that the pipe member can be inserted coaxially therethrough; a discharge passage that is connected to the third compartment, branches off from the through passage, and opens an outlet for the liquid on the outer peripheral surface of the main body;

2. The main body further includes a throttle member fitted in the outlet to direct the backflow from the first compartment to the second compartment, 2. The pump pulsation reducer according to claim 1, wherein the throttle member is in communication with the front of the second compartment with a reduced diameter, and forms a forward throttle flow passage through which the pipe member is inserted.

3. the throttle member has a base portion whose outer periphery is fitted and fixed to the discharge port, and a tubular portion extending forward from the base portion and projecting into the first compartment, the hollow portion of which forms the forward throttle flow path, The pump pulsation reducer according to claim 2, wherein a tapered portion that continuously increases in diameter in a rear end region of the front throttle passage and radially diffuses the backflow from the front throttle passage to the second partition chamber is formed in the base portion.

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