Reciprocating pump

Abstract

To provide a seal structure capable of inhibiting occurrence of cavitation.SOLUTION: A seal structure is disposed between a cylinder part 21 forming a columnar internal space and a columnar plunger 43 which reciprocates in an axial direction in the internal space. The seal structure includes: an annular seal member (a ground packing 120) disposed in the internal space; an annular pressing part 130a which is disposed adjacent to the seal member and presses the seal member in the axial direction; and a compression coil spring 140 which is disposed adjacent to the pressing part 130a. A cylindrical collar part 130b is disposed at the inner side of the compression coil spring 140 so as to partition the compression coil spring 140 from the plunger 43.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a seal structure and a reciprocating pump.

Background Art

[0002] Patent Document 1 discloses a plunger pump. In this plunger pump, a seal member and a compression coil spring are disposed on the inner peripheral portion of a seal case that defines a pump chamber. The seal member is positioned by being pressed along the axial direction by the biasing force of the compression coil spring.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional seal structure, since the space constituting the pump chamber and the space in which the compression coil spring is disposed are continuous, for example, there is a risk that cavitation is likely to occur.

[0005] One object of the present disclosure is to provide a seal structure capable of suppressing the occurrence of cavitation.

Means for Solving the Problems

[0006] One example of a seal structure is arranged between a space-forming member (21) that forms a cylindrical internal space and a cylindrical reciprocating member (40) that reciprocates axially within the internal space. The seal structure comprises an annular seal member (120) arranged in the internal space, an annular pressing portion (130a) arranged adjacent to the seal member (120) and pressing the seal member (120) in the axial direction, and a compression coil spring (140) arranged adjacent to the pressing portion (130a). A cylindrical collar portion (130b) is arranged inside the compression coil spring (140) so as to separate the compression coil spring (140) from the reciprocating member (40).

[0007] One example of a reciprocating pump includes a cylinder section (21) having an inner circumferential surface (21a) defining a cylindrical internal space, and a cylindrical plunger (43) that reciprocates axially within the internal space of the cylinder section (21). The reciprocating pump also includes an annular sealing member (120) arranged in the internal space, an annular pressing section (130a) arranged adjacent to the sealing member (120) and pressing the sealing member (120) in the axial direction, and a compression coil spring (140) arranged adjacent to the pressing section (130a). A cylindrical collar section (130b) is arranged inside the compression coil spring (140) so as to separate the compression coil spring (140) from the plunger (43).

[0008] In the above-described seal structure and reciprocating pump, a space constituting the so-called pump chamber is formed in the region axially forward of the seal member (120) within the cylindrical internal space formed by the internal space forming member (21). Since the cylindrical collar portion 130b is arranged inside the compression coil spring (140), the space in which the compression coil spring (140) is located and the space constituting the pump chamber are isolated. This makes it possible to suppress the occurrence of cavitation.

[0009] In one example, the pressing part (130a) and the collar part (130b) are integrated with each other. This configuration allows for increased efficiency in the manufacturing process by reducing the number of parts. In this example, the pressing part (130a) and the collar part (130b) may be configured as separate parts.

[0010] In one example, a regulating member (25) is placed in the internal space to restrict the position of the compression coil spring (140). With the regulating member (25) restricting the compression coil spring (140), the length of the compression coil spring (140) in the axial direction is equal to the length of the collar portion (130b) in the axial direction. In this configuration, not only the compression coil spring (140) but also the collar portion 130b presses the pressing portion 130a in the axial direction, making it possible to reduce the wire diameter of the compression coil spring (140).

[0011] In one example, the sealing member (120) has an annular recess with a V-shaped cross-section as its contact surface with the pressing portion (130a), and the pressing portion (130a) has an annular protrusion with a V-shaped cross-section corresponding to the recess as its contact surface with the sealing member (120). In this configuration, misalignment of the axes of the sealing member (120) and the pressing portion (130a) is suppressed. [Effects of the Invention]

[0012] The seal structure of this disclosure can suppress the occurrence of cavitation. [Brief explanation of the drawing]

[0013] [Figure 1] This is a cross-sectional view showing an example of a reciprocating pump. [Figure 2] Figure 1 is an enlarged cross-sectional view showing the seal structure in a reciprocating pump. [Figure 3] This is a cross-sectional view illustrating another example of a seal structure. [Figure 4] This is a cross-sectional view illustrating another example of a seal structure. [Modes for carrying out the invention]

[0014] The following describes a reciprocating pump having an example seal structure, with reference to the attached drawings. In this specification, as an example of a reciprocating pump, a so-called horizontal triple plunger pump is described, in which three plungers constituting the reciprocating member are arranged in parallel horizontally. In the following description, "up" and "down" are defined based on the state in which the reciprocating pump is mounted on a horizontal surface, and "front" and "rear" are defined based on the axial direction of the reciprocating member, with the pump chamber side being the front and the crankcase side being the rear. "Left" and "right" are based on the front-rear direction of the reciprocating pump mounted on a horizontal surface.

[0015] Figure 1 is a cross-sectional view showing one of the three plunger pumps that make up a reciprocating pump. In one example of a reciprocating pump 1, three of the pump configurations shown in Figure 1 are arranged side by side in the left-right direction (perpendicular to the plane of the paper). Figure 2 is a partially enlarged view of Figure 1. As shown in Figure 1, the reciprocating pump 1 performs its pumping action in the pump chamber 32 located at the tip of the cylinder section by the reciprocating member 40 reciprocating within the cylinder section.

[0016] The reciprocating pump 1 includes a crankcase 10, a first manifold 20, and a second manifold 30. The crankcase 10, the first manifold 20, and the second manifold 30 are integrally connected to the crankcase 10 by the second manifold 30 being fixed to the crankcase 10 via the first manifold 20 using multiple fastening means (e.g., bolts). In Figures 1 and 2, the portion of the reciprocating member 40 above the axis, indicated by the dashed line, shows the reciprocating member 40 in the state where it has advanced to the top dead center, while the portion below the axis shows the reciprocating member 40 in the state where it has retracted to the bottom dead center.

[0017] The crankcase 10 is configured to be hollow. Inside the crankcase 10, a crankshaft 12, a connecting rod 13 rotatably connected to the crankshaft 12, a piston pin 15 rotatably connecting a plunger rod 41 to the connecting rod 13, etc. are arranged, and by these, a driving part for reciprocally driving the reciprocating member 40 along the axis is constituted. Note that the plunger rod 41 constitutes the latter half of the reciprocating member 40.

[0018] The crankcase 10 includes a cylinder part 11. The cylinder part 11 has a cylindrical shape and has an axial direction orthogonal to the axial direction of the crankshaft 12. Inside the cylinder part 11, a piston pin 15 and the tip of the connecting rod 13 can be arranged.

[0019] The inside of the crankcase 10 is filled with oil for lubricating and cooling the driving part. An oil seal 16 for preventing the leakage of the oil inside the crankcase 10 is arranged at the end of the cylinder part 11 on the side of the first manifold 20. The oil seal 16 is in liquid-tight sliding contact with the outer peripheral surface of the plunger rod 41 constituting the reciprocating member 40. Then, as the crankshaft 12 rotates, the reciprocating member 40 reciprocates in the front-rear direction via the connecting rod 13 and the piston pin 15.

[0020] The first manifold 20 is arranged at the front end of the crankcase 10. Also, the second manifold 30 is arranged at the front end of the first manifold 20. The first manifold 20 has a cylinder part 21 having the same central axis as the cylinder part 11 (see FIG. 2). The cylinder part 21 penetrates the first manifold 20 in the front-rear direction. Inside the cylinder part 21, a plunger 43 constituting the first half side of the reciprocating member 40 is arranged. The plunger 43 reciprocates in the front-rear direction inside the cylinder part 21 as the crankshaft 12 rotates.

[0021] As shown in FIG. 2, an annular stepped portion 22 protruding toward the axis is formed on the inner peripheral surface 21a of the cylinder portion 21. The stepped portion 22 in the illustrated example has a front surface 22a perpendicular to the axial direction and a rear surface 22b that expands in diameter toward the rear in a cross-sectional view. In the cylinder portion 21, an annular low-pressure seal 23 such as a U-packing is disposed behind the stepped portion 22. The low-pressure seal 23 seals between the inner peripheral surface 21a of the cylinder portion 21 and the outer peripheral surface 43a of the plunger 43.

[0022] A communication pipe 25 (restricting member) connected to the second manifold 30 is provided at the front end of the cylinder portion 21. The communication pipe 25 is formed in a cylindrical shape by, for example, metal or the like. The communication pipe 25 is fitted to the cylinder portion 21 so as to protrude forward from the cylinder portion 21 by a predetermined length. In the illustrated example, a stepped portion 21b recessed radially outward is formed at the front end of the cylinder portion 21. Also, an annular stepped portion 25a protruding radially outward is formed at the center in the front-rear direction of the communication pipe 25. When the communication pipe 25 is inserted into the cylinder portion 21 from the front side of the cylinder portion 21, the stepped portion 25a of the communication pipe 25 and the stepped portion 21b of the cylinder portion 21 abut against each other, thereby positioning the communication pipe 25. As a result, the distance from the rear end of the communication pipe 25 to the stepped portion 22 of the cylinder portion 21 is determined. Also, the distance of the communication pipe 25 protruding forward from the first manifold 20 is determined. An O-ring 25b is provided at the rear end of the communication pipe 25. The space between the outer periphery of the communication pipe 25 and the inner periphery of the cylinder portion 21 is sealed by this O-ring 25b.

[0023] A seal structure 100 is disposed between the communication pipe 25 and the stepped portion 22. The seal structure 100 seals between the inner peripheral surface 21a of the cylinder portion 21 and the outer peripheral surface 43a of the plunger 43 on the front side of the stepped portion 22. The seal structure 100 has a higher pressure resistance than the low-pressure seal 23.

[0024] Furthermore, the first manifold 20 has an intake port 28 for introducing a liquid to be used, such as water (see Figure 1). The intake port 28 communicates with a flow path 31 formed in the second manifold 30. In the illustrated example, the intake port 28 is located below the cylinder portion 21.

[0025] The first manifold 20 and the second manifold 30 each have a pump chamber 32. In the illustrated example, a connecting pipe 25 is fitted into the pump chamber 32. That is, the connecting pipe 25 is housed across the inside of the second manifold 30 and the first manifold 20, thereby connecting the second manifold 30 and the first manifold 20 via the connecting pipe 25. An O-ring 25c is provided at the front end of the connecting pipe 25. The space between the outer circumference of the connecting pipe 25 and the inner circumference of the pump chamber 32 is sealed by this O-ring 25c.

[0026] The flow path 31 of the second manifold 30 communicates with the inlet 28 of the first manifold 20 and also with the discharge port 38 formed in the second manifold 30. In other words, the flow path 31 connects the inlet 28 and the discharge port 38. The flow path 31 also communicates with the pump chamber 32 at a position between the inlet 28 and the discharge port 38. In the illustrated example, the flow path 31 opens to the rear at the lower part of the second manifold 30 and communicates with the inlet 28 through this opening 31a. The flow path 31 also extends in the vertical direction, communicating with the pump chamber 32 at an opening 31b formed in the center in the vertical direction and communicating with the discharge port 38 at an opening 31c formed at the top.

[0027] The flow path 31 houses a valve assembly 50 for water intake and a valve assembly 70 for water discharge. An example of the valve assembly 50 includes a cylindrical valve seat 51, a valve 52 that seals the valve seat 51, a biasing member (compression coil spring) 53 that biases the valve 52 toward the valve seat 51, and a housing 55 that houses the biasing member 53 and the valve 52. The valve assembly 50 is positioned in the flow path such that the valve 52 is located between an opening 31b that communicates with the pump chamber 32 and an opening 31a that communicates with the suction port.

[0028] Furthermore, one example of a valve assembly 70 includes a cylindrical valve seat 71, a valve 72 that seals the valve seat 71, a biasing member (compression coil spring) 73 that biases the valve 72 toward the valve seat 71, and a housing 75 that houses the biasing member 73 and the valve 72. The valve assembly 70 is positioned in the flow path such that the valve 72 is located between an opening 31b that communicates with the pump chamber 32 and an opening 31c that communicates with the discharge port 38.

[0029] The seal structure 100 will be explained further. The seal structure 100 is formed by being positioned between a cylinder portion (space-forming member) 21 that forms a cylindrical internal space and a cylindrical plunger 43 (reciprocating member) that reciprocates within the internal space. In the illustrated example, the cylindrical internal space is defined by the inner circumferential surface 21a of the cylinder portion 21, the front surface 22a of the stepped portion 22 formed on the cylinder portion 21, and the rear surface 25d of the connecting pipe 25.

[0030] As shown in Figure 2, the seal structure 100 comprises a backup ring 110, a first gland packing 120A, a second gland packing 120B, an adapter 130, and a compression coil spring 140. The backup ring 110 is an annular member and is formed from a resin material such as polyacetal (POM) or fluororesin. The cross-section of the backup ring 110 along the radial direction is rectangular. The rear end surface of the backup ring 110 is in contact with the front surface 22a of the stepped portion 22 formed in the internal space of the cylinder portion 21. The outer circumferential surface of the backup ring is in contact with the inner circumferential surface 21a of the cylinder portion 21. A small clearance may be formed between the inner circumferential surface of the backup ring 110 and the outer circumferential surface 43a of the plunger 43.

[0031] The first gland packing 120A and the second gland packing 120B have the same shape. When not distinguished from each other, the first gland packing 120A and the second gland packing 120B are referred to as gland packing 120. The gland packing 120 is an annular member and is made of a material (rubber material, resin material, etc.) such as nitrile rubber (NBR) or fluororubber (FPM). The gland packing 120 may have higher flexibility (elasticity) than the backup ring 110. The cross-section of the gland packing 120 along the radial direction is rectangular. The outer circumferential surface of the gland packing 120 is in contact with the inner circumferential surface 21a of the cylinder portion 21. The inner circumferential surface of the gland packing 120 may be in contact with the outer circumferential surface 43a of the plunger 43. The first gland packing 120A is positioned adjacent to the backup ring 110, and the first gland packing 120A and the second gland packing 120B are arranged side by side along the axial direction. That is, the rear end surface of the first gland packing 120A is in contact with the front surface of the backup ring 110, and the rear end surface of the second gland packing 120B is in contact with the front end surface of the first gland packing 120A.

[0032] The adapter 130 is positioned adjacent to the second gland packing 120B. The adapter 130 may be made of the same resin material as the backup ring 110. The adapter 130 includes a pressing portion 130a and a collar portion 130b. The radial cross-section of the pressing portion 130a is rectangular. The rear end surface of the pressing portion 130a is in contact with the front surface of the second gland packing 120B. The outer circumferential surface of the pressing portion 130a is in contact with the inner circumferential surface 21a of the cylinder portion 21. A small clearance may be formed between the inner circumferential surface of the pressing portion 130a and the outer circumferential surface 43a of the plunger 43.

[0033] The collar portion 130b is cylindrical in shape. The collar portion 130b is formed continuously with the front surface of the pressing portion 130a. That is, the collar portion 130b and the pressing portion 130a are integrally constructed with each other. The inner circumferential surface of the collar portion 130b may be flush with the inner circumferential surface of the pressing portion 130a. Also, the outer circumferential surface of the collar portion 130b is spaced apart from the inner circumferential surface 21a of the cylinder portion 21. That is, the outer diameter of the collar portion 130b is smaller than the outer diameter of the pressing portion 130a (the inner diameter of the cylinder portion 21). The front end of the collar portion 130b abuts against the rear surface 25d of the connecting pipe 25, and the collar portion 130b is pressed toward the rear by the rear surface 25d. In this way, the connecting pipe 25 functions as a regulating member for positioning the collar portion 130b.

[0034] The compression coil spring 140 is positioned axially between the pressing portion 130a and the connecting pipe 25. In the illustrated example, the compression coil spring 140 is positioned outside the collar portion 130b and adjacent to the pressing portion 130a. That is, the collar portion 130b is positioned inside the compression coil spring 140 so as to separate the compression coil spring 140 from the plunger 43. In other words, the space in which the compression coil spring 140 is positioned and the pump chamber 32 in which the plunger 43 reciprocates are separated by the collar portion 130b.

[0035] In its natural state (i.e., unloaded), the axial length of the compression coil spring 140 is formed to be longer than the axial length of the collar portion 130b. When the seal structure 100 is positioned between the connecting pipe 25 and the stepped portion 22, and the position of the front end of the compression coil spring 140 is restricted by the connecting pipe 25, the compression coil spring 140 is compressed, and its axial length becomes equal to the axial length of the collar portion 130b. In this state, the compression coil spring 140 biases (presses) the pressing portion 130a (adapter 130) toward the rear.

[0036] As described above, one example of a reciprocating pump comprises a cylinder portion 21 having an inner circumferential surface 21a defining a cylindrical internal space, and a cylindrical plunger 43 that reciprocates axially within the internal space of the cylinder portion 21. The reciprocating pump comprises an annular gland packing 120 (sealing member) arranged in the internal space, an annular pressing portion 130a arranged adjacent to the gland packing 120 and pressing the gland packing 120 axially, and a compression coil spring 140 arranged adjacent to the pressing portion 130a. A cylindrical collar portion 130b is arranged inside the compression coil spring 140 so as to separate the compression coil spring 140 from the plunger 43.

[0037] In the reciprocating pump described above, the space constituting the pump chamber 32 is formed in the region axially forward of the gland packing 120 within the cylindrical internal space formed by the cylinder portion 21 (internal space forming member). Since the cylindrical collar portion 130b is positioned inside the compression coil spring 140, the space in which the compression coil spring 140 is located and the space constituting the pump chamber 32 are isolated. This suppresses the occurrence of cavitation.

[0038] Furthermore, the above-described seal structure effectively suppresses an increase in the volume of the pump chamber 32. This increases the compression ratio of the pump, thereby improving water absorption efficiency. In addition, the occurrence of displacement of the compression coil spring 140 in the radial direction (direction intersecting the axial direction) is suppressed. In this case, eccentricity of the load position of the compression coil spring 140 on the gland packing 120 can be suppressed. Also, contact between the compression coil spring 140 and the plunger 43 is prevented.

[0039] In one example, a connecting pipe 25 (regulating member) is placed in the internal space of the cylinder portion 21 to restrict the position of the compression coil spring 140. With the connecting pipe 25 restricting the position of the compression coil spring 140, the length of the compression coil spring 140 in the axial direction is equal to the length of the collar portion 130b in the axial direction. In this configuration, not only the compression coil spring 140 but also the collar portion 130b presses the pressing portion 130a in the axial direction, making it possible to reduce the wire diameter of the compression coil spring 140.

[0040] Figure 3 is a cross-sectional view illustrating another example of a seal structure. The reciprocating pump shown in Figure 3 has a seal structure 200 instead of a seal structure 100. The seal structure 200 includes a female adapter (backup ring) 210, a first V-packing 220A, a second V-packing 220B, a male adapter 230, and a compression coil spring 140.

[0041] The female adapter 210 is an annular member and is made of the same resin material as the backup ring 110. The rear end surface of the female adapter 210 is in contact with the stepped portion 22 formed in the internal space of the cylinder portion 21 and is formed to be flat. The outer circumferential surface of the female adapter 210 is in contact with the inner circumferential surface 21a of the cylinder portion 21. A small clearance may be formed between the inner circumferential surface of the female adapter 210 and the outer circumferential surface 43a of the plunger 43. A V-shaped groove (recess) 211 is formed on the front surface of the female adapter 210, which is concave toward the rear.

[0042] The first V-packing 220A and the second V-packing 220B have the same shape. When not distinguished from each other, the first V-packing 220A and the second V-packing 220B are referred to as V-packing 220. V-packing 220 is an annular member and is made of the same resin material as gland packing 120. The outer circumferential surface of V-packing 220 is in contact with the inner circumferential surface 21a of cylinder portion 21. The inner circumferential surface of V-packing 220 may be in contact with the outer circumferential surface 43a of plunger 43. The first V-packing 220A is positioned adjacent to the female adapter 210, and the first V-packing 220A and the second V-packing 220B are arranged side by side along the axial direction. Specifically, the rear end surface of the first V-packing 220A is in contact with the front surface of the female adapter 210, and the rear end surface of the second V-packing 220B is in contact with the front end surface of the first V-packing 220A. The cross-section of the V-packing 220 along the radial direction is approximately V-shaped. That is, the rear surface of the V-packing 220 has a V-shaped protrusion 222 formed convexly toward the rear, and the front surface of the V-packing 220 has a V-shaped groove (recess) 221 formed concavely toward the rear. The shape of the protrusion 222 of the V-packing 220 corresponds to the shape of the groove 211 of the female adapter 210. Therefore, when the V-packing 220 is pressed toward the female adapter 210, the protrusion 222 comes into close contact with the groove 211. Furthermore, the shape of the protrusion 222 of the V-packing 220 also corresponds to the shape of the groove 221 of the V-packing 220. Therefore, when the second V-packing 220B is pressed toward the first V-packing 220A, the protrusion 222 of the second V-packing 220B comes into close contact with the groove 221 of the first V-packing 220A.

[0043] The male adapter 230 is positioned adjacent to the second V-packing 220B. The male adapter 230 may be made of the same resin material as the female adapter 210. The male adapter 230 includes a pressing portion 230a and a collar portion 230b. The rear end surface of the pressing portion 230a is in contact with the front surface of the second V-packing 220B. The outer circumferential surface of the pressing portion 230a is in contact with the inner circumferential surface 21a of the cylinder portion 21. A small clearance may be formed between the inner circumferential surface of the pressing portion 230a and the outer circumferential surface 43a of the plunger 43. A V-shaped protrusion 231 is formed on the rear surface of the pressing portion 230a, which is convex toward the rear. The shape of the protrusion 231 of the pressing portion 230a corresponds to the shape of the groove 221 of the second V-packing 220B. Therefore, when the pressing portion 230a is pressed toward the second V-packing 220B, the protrusion 231 comes into close contact with the groove 221.

[0044] The collar portion 230b is cylindrical in shape. The collar portion 230b is formed continuously with the front surface of the pressing portion 230a. That is, the collar portion 230b and the pressing portion 230a are integrally formed with each other. The inner circumferential surface of the collar portion 230b is flush with the inner circumferential surface of the pressing portion 230a. The outer circumferential surface of the collar portion 230b is spaced apart from the inner circumferential surface 21a of the cylinder portion 21. That is, the outer diameter of the collar portion 230b is smaller than the outer diameter of the pressing portion 230a. The front end of the collar portion 230b is pressed toward the rear by the rear surface 25d of the connecting pipe 25.

[0045] In the illustrated example, the compression coil spring 140 is positioned outside the collar portion 230b and adjacent to the pressing portion 230a. That is, the collar portion 230b is positioned inside the compression coil spring 140 so as to separate the compression coil spring 140 from the plunger 43. In other words, the space in which the compression coil spring 140 is located and the pump chamber 32 in which the plunger 43 reciprocates are separated by the collar portion 230b.

[0046] In its natural state, the axial length of the compression coil spring 140 is formed to be longer than the axial length of the collar portion 230b. When the seal structure 200 is positioned between the connecting pipe 25 and the stepped portion 22, and the position of the front end of the compression coil spring 140 is restricted by the connecting pipe 25, the compression coil spring 140 is compressed, and its axial length becomes equal to the axial length of the collar portion 230b. In this state, the compression coil spring 140 biases the pressing portion 230a (male adapter 230) toward the rear.

[0047] As described above, in the configuration shown in Figure 3, the V-packing 220 has an annular groove 221 with a V-shaped cross-section as a contact surface with the pressing portion 230a, and the pressing portion 230a has an annular protrusion 231 with a V-shaped cross-section corresponding to the groove 221 as a contact surface with the V-packing 220. In this configuration, misalignment of the axes of the V-packing 220 and the pressing portion 230a is suppressed. In addition, since the load of the compression coil spring 140 is reliably applied to the groove 221 of the V-packing 220, uneven wear of the V-packing 220 is suppressed, and the durability of the V-packing 220 is improved.

[0048] Figure 4 is a cross-sectional view illustrating yet another example of a seal structure. The reciprocating pump shown in Figure 4 has a seal structure 300 instead of a seal structure 100. The seal structure 300 includes a backup ring 110, a first gland packing 120A, a second gland packing 120B, a pressing member 330a, a collar member 330b, and a compression coil spring 140. The reciprocating pump in Figure 4 also has a connecting pipe 325 instead of a connecting pipe 25.

[0049] The connecting pipe 325 differs from the connecting pipe 25 only in that it has a stepped portion 325f. The stepped portion 325f is formed along the inner edge of the rear surface 325d of the connecting pipe 325. The stepped portion 325f has a rectangular cross-section and is recessed from the rear surface 325d toward the front.

[0050] The pressing member 330a has an annular shape. The cross-section of the pressing member 330a along the radial direction is substantially rectangular. The rear end surface of the pressing member 330a is in contact with the front surface of the second gland packing 120B. The outer circumferential surface of the pressing member 330a is in contact with the inner circumferential surface 21a of the cylinder portion 21. A small clearance may be formed between the inner circumferential surface of the pressing member 330a and the outer circumferential surface 43a of the plunger 43. A stepped portion 331 is formed on the front surface 332 of the pressing member 330a. The stepped portion 331 is formed along the inner circumference of the front surface 332. The stepped portion 331 has a rectangular cross-section and is recessed toward the rear from the front surface 332.

[0051] The collar member 330b is cylindrical, similar to the collar portion 130b, and is positioned inside the compression coil spring 140. The collar member 330b is also positioned between the stepped portion 331 of the pressing portion 130a and the stepped portion 325f of the connecting pipe 325. The inner circumferential surface of the collar member 330b is flush with the inner circumferential surface of the pressing member 330a. Furthermore, the outer circumferential surface of the collar member 330b is spaced apart from the inner circumferential surface 21a of the cylinder portion 21. In other words, the outer diameter of the collar member 330b is smaller than the outer diameter of the pressing member 330a.

[0052] In the example shown in Figure 2, the adapter 130 is constructed by integrally forming the collar portion 130b and the pressing portion 130a. However, as shown in Figure 4, the collar portion 130b (collar member 330b) and the pressing portion 130a (pressing member 330a) may be constructed as separate parts. In the configuration where the pressing portion 130a and the collar portion 130b are integrated, as in the example in Figure 2, the number of parts can be reduced, thereby improving the efficiency of the manufacturing process.

[0053] While embodiments of the present disclosure have been described above, the specific forms of the present disclosure are not limited to the examples above. For example, the sealing structure of the present disclosure may be applied not only to cylinders adjacent to the pump chamber, but also to cylinders located in other parts of the chamber.

[0054] Figure 4 shows an example in which the collar portion 130b and the pressing portion 130a of the adapter 130 in Figure 2 are configured separately. However, for example, the collar portion 230b and the pressing portion 230a constituting the male adapter 230 in Figure 3 may be configured separately from each other. Furthermore, the collar portion may be formed as part of a connecting pipe. That is, the connecting pipe may include a cylindrical collar portion arranged inside the compression coil spring.

[0055] Furthermore, although an example was shown in which the seal structure is sandwiched between the rear end of the connecting pipe and the stepped portion of the cylinder, the seal structure only needs to be sandwiched between two opposing surfaces, and the arrangement between which surfaces is placed can be appropriately changed depending on the object to which the seal structure is applied.

[0056] Embodiments illustrated in this disclosure may be described as follows: [Form 1] A seal structure disposed between a space-forming member (21) that forms a cylindrical internal space and a cylindrical reciprocating member (40) that reciprocates axially within the internal space, An annular sealing member (120) arranged in the internal space, An annular pressing portion (130a) is positioned adjacent to the sealing member (120) and presses the sealing member (120) in the axial direction, The device comprises a compression coil spring (140) positioned adjacent to the pressing portion (130a), A seal structure in which a cylindrical collar portion (130b) is positioned inside the compression coil spring (140) so as to separate the compression coil spring (140) from the reciprocating member (40). [Form 2] The sealing structure according to Embodiment 1, wherein the pressing portion (130a) and the collar portion (130b) are integrated with each other. [Form 3] The sealing structure according to Embodiment 1, wherein the pressing portion (130a) and the collar portion (130b) are configured as separate components. [Form 4] A regulating member (25) for regulating the position of the compression coil spring (140) is arranged in the internal space. A seal structure according to any one of embodiments 1 to 3, wherein, with the restricting member (25) restricting the compression coil spring (140), the length of the compression coil spring (140) in the axial direction is equal to the length of the collar portion (130b) in the axial direction. [Form 5] The sealing member (120) has an annular recess with a V-shaped cross-section as a contact surface with the pressing portion (130a), The sealing structure according to any one of embodiments 1 to 4, wherein the pressing portion (130a) has an annular protrusion with a V-shaped cross-section corresponding to the recess, as a contact surface with the sealing member (120). [Form 6] A cylinder portion (21) having an inner circumferential surface (21a) that defines a cylindrical internal space, A reciprocating pump comprising a cylindrical plunger (43) that reciprocates axially within the internal space of the cylinder portion (21), An annular sealing member (120) arranged in the internal space, An annular pressing portion (130a) is positioned adjacent to the sealing member (120) and presses the sealing member (120) in the axial direction, The device comprises a compression coil spring (140) positioned adjacent to the pressing portion (130a), A reciprocating pump in which a cylindrical collar portion (130b) is positioned inside the compression coil spring (140) so as to separate the compression coil spring (140) and the plunger (43). [Explanation of Symbols]

[0057] 1... Reciprocating pump, 21... Cylinder section (space forming member), 40... Reciprocating member, 100... Seal structure (seal structure), 120... Gland packing (seal member), 130a... Pressing part, 130b... Collar part, 140... Compression coil spring.

Claims

1. A cylinder portion (21) having an inner circumferential surface (21a) that defines a cylindrical internal space, A reciprocating pump comprising a cylindrical plunger (43) that reciprocates axially within the internal space of the cylinder portion (21), An annular sealing member (120) arranged in the internal space, An annular pressing portion (130a) is positioned adjacent to the sealing member (120) and presses the sealing member (120) in the axial direction, A compression coil spring (140) is positioned adjacent to the pressing portion (130a), A reciprocating pump comprising a cylindrical collar portion (130b) that is externally fitted to the plunger (43) and internally fitted to the compression coil spring (140), so as to separate the compression coil spring (140) and the plunger (43).

2. The reciprocating pump according to claim 1, wherein the pressing portion (130a) and the collar portion (130b) are integrally formed with each other.

3. The reciprocating pump according to claim 1, wherein the pressing portion (130a) and the collar portion (130b) are configured as separate components.

4. A regulating member (25) for regulating the position of the compression coil spring (140) is arranged in the internal space. The reciprocating pump according to claim 1, wherein, with the restricting member (25) restricting the compression coil spring (140), the length of the compression coil spring (140) in the axial direction is equal to the length of the collar portion (130b) in the axial direction.

5. The sealing member (120) has an annular recess with a V-shaped cross-section as a contact surface with the pressing portion (130a), The reciprocating pump according to any one of claims 1 to 4, wherein the pressing portion (130a) has an annular protrusion with a V-shaped cross-section corresponding to the recess, as a contact surface with the sealing member (120).

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