Reciprocating action pump

Abstract

The reciprocating pump includes: a pump body having a piston for compressing liquid and a cylinder covering the piston from the outside; a drive unit that causes the piston to reciprocate in a reciprocating direction; and piston rings disposed in the gap between the piston and the cylinder, with an annular groove formed on the outer circumferential surface of the piston. The space inside the cylinder is divided by the piston rings into a high-pressure region where the compressed liquid flows and a low-pressure region where the internal pressure is lower than that of the high-pressure region. The piston rings have a high-pressure side ring disposed on the high-pressure side of the annular groove and a low-pressure side ring disposed on the low-pressure side of the annular groove relative to the high-pressure side ring. A cut surface that retracts toward the high-pressure side is formed on the outer circumferential edge of the low-pressure side ring facing the low-pressure side.

Description

Technical Field

[0001] This disclosure relates to a reciprocating pump.

[0002] This application claims priority to Japanese Patent Application No. 2023-201753, filed in Japan on November 29, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] Reciprocating pumps have been used to date as devices for compressing liquid hydrogen. For example, such pumps can pressurize liquid hydrogen to approximately 90 MPa. Specifically, a reciprocating pump mainly comprises a piston that reciprocates along its axis and a cylinder that covers the piston from the outside. By the reciprocating motion of the piston within the cylinder, liquid hydrogen is sequentially compressed and extracted to the outside. The piston is driven by a drive unit.

[0004] A circumferentially extending annular groove is formed on the outer peripheral surface of the piston, and a piston ring is inserted into the annular groove. The piston ring is composed of a high-pressure side ring and a low-pressure side ring, as described in Patent Document 1 below. In either ring, the surface facing the reciprocating direction is generally planar.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent No. 6424369 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] Here, when the end face of the low-pressure side ring is flat, sometimes the pressure on the high-pressure area side (for example, around 90 MPa) causes the outer peripheral edge of the low-pressure side ring to deform by being pressed inward toward the gap (i.e., the low-pressure area side). As a result, the contact area between the outer peripheral surface of the low-pressure side ring and the inner peripheral surface of the cylinder decreases, reducing the amount of deformation. Consequently, problems arise such as reduced sealing performance and uneven wear on the outer peripheral surface of the ring.

[0010] This invention provides a reciprocating pump with piston rings that provide superior sealing performance.

[0011] Technical solutions for solving technical problems

[0012] The reciprocating pump disclosed herein comprises: a pump body having a piston for compressing liquid and a cylinder covering the piston from the outside; a drive unit for reciprocating the piston relative to the cylinder in a reciprocating direction; a piston ring disposed in the gap between the piston and the cylinder, having an annular groove formed on the outer peripheral surface of the piston that is recessed toward the inner peripheral side and extends circumferentially throughout the outer peripheral surface; the space inside the cylinder being divided by the piston ring into a high-pressure region where the compressed liquid flows and a low-pressure region where the internal pressure is lower than that of the high-pressure region; the piston ring having a high-pressure side ring disposed on the high-pressure side of the annular groove and a low-pressure side ring disposed on the low-pressure side of the annular groove relative to the high-pressure side ring; and a cut surface that retracts toward the high-pressure side being formed at the outer peripheral side of the low-pressure side ring facing the low-pressure side.

[0013] Invention Effects

[0014] According to the present invention, a reciprocating pump with piston rings that provide higher sealing performance can be provided. Attached Figure Description

[0015] Figure 1 This is a longitudinal cross-sectional view showing the structure of the reciprocating pump according to the first embodiment of the present invention.

[0016] Figure 2 This is an enlarged cross-sectional view of the main part of the reciprocating pump according to the first embodiment of the present invention.

[0017] Figure 3 This is a perspective view showing the structure of the low-pressure side ring according to the first embodiment of this disclosure.

[0018] Figure 4 This is a top view showing the structure of the piston ring according to the first embodiment of this disclosure.

[0019] Figure 5 This is an explanatory diagram showing the dimensions of the main parts of the reciprocating pump according to the first embodiment of the present invention.

[0020] Figure 6 This is an enlarged cross-sectional view of the main part of the reciprocating pump according to the second embodiment of the present invention.

[0021] Figure 7 This is an enlarged cross-sectional view of the main part of the reciprocating pump according to the third embodiment of the present invention.

[0022] Figure 8 This is an enlarged cross-sectional view of the main part of a first modified example of a reciprocating pump according to various embodiments of the present invention.

[0023] Figure 9 This is an enlarged cross-sectional view of the main part of a second modified example of a reciprocating pump according to various embodiments of the present invention.

[0024] Figure 10 This is an enlarged cross-sectional view of the main part of a third modified example of a reciprocating pump according to various embodiments of the present invention.

[0025] Figure 11 This is an explanatory diagram showing the operation of the piston ring under high pressure in the reference example. Detailed Implementation

[0026] <First Implementation Method>

[0027] The following is for reference Figures 1 to 5 The reciprocating pump 100 of the first embodiment of the present invention will be described.

[0028] (Structure of reciprocating pump 100)

[0029] As an example, the reciprocating pump 100 is a device used to pressurize extremely low-temperature liquids such as liquid hydrogen to high pressure (around 90 MPa). Figure 1 As shown, the reciprocating pump 100 includes a piston 1, a cylinder 2, a drive unit 3, a housing 4, a check valve 5, a discharge pipe 6, and a discharge valve 7. The piston 1 and the cylinder 2 constitute the pump body 9.

[0030] (Structure of piston 1)

[0031] The piston 1 has a cylindrical piston body 10 extending vertically and centered on an axis O, a wear-resistant ring 11 mounted on the piston body 10, and piston rings 12. The radial dimension of the piston body 10 is constant throughout the entire region along the axis O. The wear-resistant ring 11 is disposed at the front end of the piston body 10. The wear-resistant ring 11 is annular in shape centered on the axis O and is formed of resin material.

[0032] A wear-resistant ring 11 is provided at the lower end of the piston body 10, and another wear-resistant ring 11 is provided at intervals along the axis O from this wear-resistant ring 11. Between these pairs of wear-resistant rings 11, a plurality of piston rings 12 (in one example, six) are arranged at intervals along the axis O. The wear-resistant rings 11 are provided to guide the piston body 10 along the inner circumferential surface of the cylinder 2, which will be described later. On the other hand, the piston rings 12 are provided to maintain liquid and gas tightness between themselves and the inner circumferential surface of the cylinder 2. The structure of the piston rings 12 will be described later.

[0033] (Structure of cylinder 2)

[0034] Cylinder 2 is a bottomed cylindrical shape that covers piston 1 from the outer periphery. Piston 1 is inserted into the interior of cylinder 2 through the upper opening h. The space inside cylinder 2, below the front end of piston 1, is a compression chamber 21. A check valve 5 is provided at the bottom of cylinder 2 for guiding liquid hydrogen into the compression chamber 21. This check valve 5 allows liquid hydrogen to flow only from the outside of cylinder 2 toward the inside of the compression chamber 21. In other words, even if the pressure in the compression chamber 21 increases, liquid hydrogen will not flow out of cylinder 2 through the check valve 5.

[0035] A discharge pipe 6 is connected to the side of cylinder 2, specifically to the portion facing the compression chamber 21. The discharge pipe 6 is provided for removing the liquid hydrogen compressed in the compression chamber 21 to the outside of cylinder 2. A discharge valve 7 is provided on the discharge pipe 6. When the pressure inside the compression chamber 21 reaches a predetermined value or higher, the discharge valve 7 allows liquid hydrogen to flow only in the direction from the compression chamber 21 toward the outside.

[0036] (Structure of drive unit 3)

[0037] The piston 1 described above reciprocates in the direction of axis O by being driven by the drive unit 3 within the cylinder 2. The drive unit 3 utilizes an electric motor (not shown) and a linkage mechanism to cause the piston 1 to reciprocate within the cylinder 2.

[0038] (Structure of outer shell 4)

[0039] The outer casing 4 is a container that covers the cylinder 2 from the outside. The outer casing 4 has a bottomed cylindrical body 41, a supply pipe 42, and a gas discharge pipe 43. The supply pipe 42 is a piping for guiding liquid hydrogen from an external supply source into the outer casing 41 (liquid storage chamber 44). The supply pipe 42 is located near the bottom surface of the outer casing 41. The gas discharge pipe 43 is provided for discharging the vaporized components (gas components) within the liquid storage chamber 44 to the outside. The gas discharge pipe 43 is located at a position separated from the supply pipe 42 by upwards. Furthermore, the liquid level of the liquid hydrogen within the liquid storage chamber 44 is adjusted to be located below the gas discharge pipe 43. Additionally, the aforementioned discharge pipe 6 extends to the outside of the outer casing 4.

[0040] (Structure of piston ring 12)

[0041] Next, refer to Figures 2 to 5 The structure of piston ring 12 is described in detail. Piston ring 12 divides the space within cylinder 2 into a high-pressure region V1 and a low-pressure region V2 connected along axis O. High-pressure region V1 is the region on the compression chamber 21 side within cylinder 2, and low-pressure region V2 is the region located opposite to compression chamber 21, separated by piston ring 12. In the following description, the high-pressure region V1 side is sometimes simply referred to as the "high-pressure side," and the low-pressure region V2 side is sometimes simply referred to as the "low-pressure side."

[0042] like Figure 2 As shown, piston ring 12 is housed in an annular groove 30 formed on the outer peripheral surface of piston body 10. The annular groove 30 is a groove with a rectangular cross-section extending circumferentially around axis O and recessed towards the inner peripheral side. The annular groove 30 is formed by a bottom wall surface 31, a low-pressure side wall surface 32, and a high-pressure side wall surface 33. The bottom wall surface 31 is a surface facing outwards and is cylindrical around axis O. The low-pressure side wall surface 32 is annular, extending from the low-pressure side (i.e., upper side) end edge of the bottom wall surface 31 towards the outer peripheral side. In a cross-section including axis O, the low-pressure side wall surface 32 extends radially. The high-pressure side wall surface 33 is annular, extending from the high-pressure side (i.e., lower side) end edge of the bottom wall surface 31 towards the outer peripheral side. In a cross-section including axis O, the high-pressure side wall surface 33 extends radially.

[0043] The piston ring 12 has a high-pressure side ring 50, a low-pressure side ring 60, a support ring 70, and a spring component 80. The high-pressure side ring 50 is disposed on the high-pressure side of the annular groove 30, i.e., below in the vertical direction. The low-pressure side ring 60 is disposed on the low-pressure side of the annular groove 30, i.e., above the high-pressure side ring 50. These high-pressure side rings 50 and low-pressure side rings 60 abut against each other in the direction of axis O.

[0044] Here, as Figure 3 As shown, the low-pressure side ring 60 is annular with axis O as its center. Furthermore, an opening called a mortise P is formed on a portion of the circumference of the low-pressure side ring 60. This mortise P is provided to allow the low-pressure side ring 60 to deform in an enlarging manner and insert into the annular groove 30 of the piston body 10 from its outer periphery. The high-pressure side ring 50 is also annular with the same mortise P as the low-pressure side ring 60. On the other hand, as... Figure 4 As shown, the joint P of the high-pressure side ring 50 and the joint P of the low-pressure side ring 60 are 180° out of phase in the circumferential direction. That is, if the joints P overlap, liquid leakage will occur through them. To prevent leakage, as described above, the joints P are out of phase.

[0045] like Figure 2 As shown, the high-pressure side ring 50 has a first outer peripheral surface 51, a first abutting surface 52, a first inner peripheral surface 53, and a first bottom surface 54. The first outer peripheral surface 51 is a surface facing the outer peripheral side and is cylindrical about the circumferential direction of the axis O. The first outer peripheral surface 51 contacts the inner peripheral surface of the cylinder 2 and slides along the axis O as the piston 1 reciprocates. The first abutting surface 52 is a surface facing the low-pressure side (i.e., the upper side) and is annular about the axis O. In the cross-sectional view including the axis O, the first abutting surface 52 extends radially relative to the axis O. The first abutting surface 52 contacts the surface of the low-pressure side ring 60. The first inner peripheral surface 53 is a surface facing the inner peripheral side and is cylindrical about the circumferential direction of the axis O. The first bottom surface 54 is a surface facing the high-pressure side and is opposite to the high-pressure side wall surface 33 of the annular groove 30.

[0046] The low-pressure side ring 60 has a second outer peripheral surface 61, a second abutting surface 62, a second inner peripheral surface 63, a second bottom surface 64, and a cut surface 65. The second outer peripheral surface 61 is the surface facing the outer peripheral side and is cylindrical about the circumferential direction of axis O. The second outer peripheral surface 61 contacts the inner peripheral surface of cylinder 2 and slides along axis O as piston 1 reciprocates. The second abutting surface 62 is the surface facing the low-pressure side (i.e., the upper side) and is annular about axis O. In a cross-sectional view including axis O, the second abutting surface 62 extends radially relative to axis O. The second abutting surface 62 contacts the low-pressure side wall surface 32 of the annular groove 30. The second inner peripheral surface 63 is the surface facing the inner peripheral side and is cylindrical about the circumferential direction of axis O. The second bottom surface 64 is the surface facing the high-pressure side and contacts the first abutting surface 52 of the high-pressure side ring 50.

[0047] The cut surface 65 extends between the second abutment surface 62 and the second outer peripheral surface 61. The cut surface 65 recedes toward the high-pressure side in a cross-sectional view including the axis O. More specifically, the cut surface 65 extends from the low-pressure side toward the high-pressure side as it moves from the inner peripheral side toward the outer peripheral side. In this embodiment, the angle formed by the cut surface 65 with respect to the axis O is constant throughout the radial region. Additionally, as... Figure 5 As shown, when the radial clearance between the outer circumferential surface of the piston body 10 and the inner circumferential surface of the cylinder 2 is set to G, the radial dimension A of the cut surface 65 is set to satisfy G≤A≤2G. That is, the end edge of the inner circumferential side of the cut surface 65 is located at the same radial position as the end edge of the outer circumferential side of the low-pressure side wall 32 of the annular groove 30, or at a position radially inward than the end edge of that outer circumferential side. More preferably, G≤A≤1.8G. Most preferably, G≤A≤1.5G. In addition, in this embodiment, the dimension of the low-pressure side ring 60 in the axial direction O is equal to the dimension of the high-pressure side ring 50 in the axial direction O. Furthermore, the term "same" or "equal" here refers to substantial identity, allowing for minor errors.

[0048] Resin materials are preferably used as the materials constituting the high-pressure side ring 50 and the low-pressure side ring 60. Specifically, at least one selected from PTFE (polytetrafluoroethylene), PI (polyimide), PAI (polyamide-imide), PPA (polyphthalamide), PPS (polyphenylene sulfide), PSU (polysulfone), and PES (polyethersulfone) is preferred as the main component. Because these resin materials are relatively soft, sintering during sliding with cylinder 2 and flame retardancy can be ensured when the liquid is flammable.

[0049] like Figure 2As shown, a support ring 70 is disposed on the inner circumference of the aforementioned high-pressure side ring 50 and low-pressure side ring 60. The support ring 70 is annular about axis O. The dimension of the support ring 70 in the axis O direction is equal to the sum of the dimensions of the high-pressure side ring 50 and the low-pressure side ring 60 in the axis O direction. The support ring 70 is subjected to force from the inner circumference by a spring member 80. The spring member 80 is an annular elastic body that applies force to expand the diameter of the support ring 70 toward the outer circumference. The configuration is such that, by being pushed from the inner circumference by these support rings 70 and the spring member 80, the high-pressure side ring 50 and the low-pressure side ring 60 are normally in sliding contact with the inner circumference surface of the cylinder 2. Therefore, a certain space is formed between the inner circumference surface of the support ring 70 and the bottom wall surface 31 of the annular groove 30.

[0050] (Effects)

[0051] When the reciprocating pump 100 is operated, firstly, with liquid hydrogen supplied to the cylinder 2 via the supply pipe 42, the piston 1 is reciprocated within the cylinder 2 by the drive unit 3. As a result, the liquid hydrogen within the cylinder 2 is sequentially compressed to a high-pressure state. The high-pressure liquid hydrogen is then extracted to the outside through the discharge pipe 6.

[0052] Here, unlike the structure described above, when the end face of the low-pressure side ring 160 is planar without forming the notch 65, sometimes the outer peripheral edge of the low-pressure side ring 160 deforms by being pressed toward the inside of the gap (i.e., the low-pressure region V2 side) due to the pressure on the high-pressure region V1 side (approximately 90 MPa in one example). (Ref.) Figure 11 (See the reference example shown.) Therefore, the contact area between the outer peripheral surface of the low-pressure side ring 160 and the inner peripheral surface of the cylinder 2 is reduced by the amount of deformation. As a result, there are issues of reduced sealing performance of the low-pressure side ring 160 and uneven wear occurring on the outer peripheral surface of the low-pressure side ring 160. To solve these problems, the structures described above are employed in this embodiment.

[0053] According to the above structure, a notch 65 is pre-formed in the outer peripheral region, which is prone to deformation under pressure. Therefore, even when high pressure is applied to the outer peripheral edge, deformation towards the low-pressure region V2 can be allowed to a certain extent, corresponding to the amount of the notch. This reduces the possibility of a portion of the low-pressure side ring 60 being pressed into the gap between the piston 1 and the cylinder 2. Consequently, a reduction in the contact area between the low-pressure side ring 60 and the cylinder 2 is avoided. Furthermore, detachment of deformed portions is also prevented. Therefore, a decrease in sealing performance can be avoided, allowing for long-term stable operation of the reciprocating pump 100.

[0054] The cut surface 65 extends from the low-pressure region V2 side toward the high-pressure region V1 side as it moves from the inner peripheral side toward the outer peripheral side.

[0055] According to the above structure, the cut surface 65 extends from the inner peripheral side to the outer peripheral side and from the low-pressure side to the high-pressure side. Therefore, the cut surface 65 can be formed simply by chamfering, thus achieving ease of machining. Consequently, the maintenance or manufacturing costs of the reciprocating pump 100 can be reduced.

[0056] According to the above structure, the radial dimension of the cut surface 65 is within a range greater than the radial dimension of the gap between the piston 1 and the cylinder 2 and less than twice the radial dimension of that gap. This provides a margin of safety, preventing deformation of the low-pressure side ring 60 and the resulting decrease in sealing performance. Therefore, the reciprocating pump 100 can be used stably and continuously for an extended period.

[0057] The first embodiment of this disclosure has been described above. Furthermore, various changes and modifications can be made to the above structure without departing from the spirit of this disclosure.

[0058] <Second Implementation Method>

[0059] Next, refer to Figure 6 The second embodiment of this disclosure will be described. Furthermore, structures identical to those in the first embodiment described above will be labeled with the same reference numerals, and detailed descriptions will be omitted.

[0060] like Figure 6 As shown, in this embodiment, the cross-sectional shape of the low-pressure side ring 60 is different from that in the first embodiment described above. Specifically, in addition to the second outer peripheral surface 61, the second abutment surface 62, the second inner peripheral surface 63, the second bottom surface 64, and the cut surface 65 described above, the low-pressure side ring 60 also has a second cut surface 66.

[0061] A second cut surface 66 is disposed between the second bottom surface 64 and the second outer peripheral surface 61. The second cut surface 66 is recessed toward the low-pressure side. More specifically, in a cross-sectional view including axis O, the second cut surface 66 extends from the high-pressure side toward the low-pressure side as it moves from the inner peripheral side toward the outer peripheral side. The angle formed by the second cut surface 66 with respect to axis O is constant throughout the entire radial region. Furthermore, the radial dimension of the second cut surface 66 is preferably set to converge to the same numerical range as the radial dimension of the cut surface 65 described in the first embodiment.

[0062] (Effects)

[0063] According to the above structure, in addition to the cut surface 65 formed on the surface facing the low-pressure region V2, a second cut surface 66 is also formed on the surface facing the low-pressure region V2. Therefore, in addition to avoiding a decrease in sealing performance caused by a portion of the ring being pressed into the gap between the piston 1 and the cylinder 2, the assembly direction of the low-pressure side ring 60 does not need to be specified during assembly. Thus, efficient and rapid assembly operations can be achieved. Furthermore, the possibility of malfunctions in the final product due to assembly errors can be reduced.

[0064] The second embodiment of this disclosure has been described above. Furthermore, various changes and modifications can be made to the above structure without departing from the spirit of this disclosure.

[0065] <Third Implementation Method>

[0066] Next, refer to Figure 7 The third embodiment of this disclosure will be described. Furthermore, structures identical to those in the embodiments described above will be labeled with the same reference numerals, and detailed descriptions will be omitted.

[0067] In this embodiment, the shapes (i.e., the surface structures of these rings) of the high-voltage side ring 50 and the low-voltage side ring 60 are the same as in the first embodiment described above. However, the dimensions of the high-voltage side ring 50 and the low-voltage side ring 60 in the axial direction O differ from those in the first embodiment. Specifically, when the dimension of the high-voltage side ring 50 in the axial direction O is defined as X, and the dimension of the low-voltage side ring 60 in the axial direction O is defined as Y, X ≥ 1.5Y. More preferably, X ≥ 1.7Y. Most preferably, X ≥ 2.0Y.

[0068] (Effects)

[0069] Here, openings (joints P) for inserting these components relative to the piston 1 are formed in a portion of the circumferential direction of the high-pressure side ring 50 and the low-pressure side ring 60. The joints P of the high-pressure side ring 50 are typically assembled such that their circumferential positions differ by 180° from those of the low-pressure side ring 60. However, due to years of use, wear sometimes occurs in the low-pressure side ring 60 towards the radially inward side. This results in deformation where the joints P of the low-pressure side ring 60 expands circumferentially to both sides. Consequently, through this joint P, a portion of the high-pressure side ring 50 deforms in a way that bulges towards the low-pressure region V2, potentially leading to breakage of the high-pressure side ring 50. However, according to the above structure, the dimension of the high-pressure side ring 50 in the reciprocating direction is set larger than that of the low-pressure side ring 60, thus increasing the rigidity of the high-pressure side ring 50. Therefore, deformation at the joint P as described above is less likely to occur. Therefore, it can suppress the deterioration and deformation caused by years of use of piston ring 12, thus enabling the reciprocating pump 100 to continue to operate stably for a longer period of time.

[0070] <Other Implementation Methods>

[0071] The various embodiments of this disclosure have been described above. Furthermore, various changes and modifications can be made to the above structures without departing from the spirit of this disclosure.

[0072] <First Variation>

[0073] As the first variant of the low-pressure side ring 60, it can also be adopted Figure 8 The structure shown is illustrated. In the example shown, the cut surface 65 is a convex curved surface protruding towards the low-pressure side. This cut surface 65 can be an arc shape or a curved surface with gradually changing curvature. Furthermore, this variation can be applied to any combination of the first to third embodiments described above.

[0074] According to the above structure, the cut surface 65 is a convex curved surface that protrudes towards the low-pressure region V2, thus avoiding stress concentration at the cut surface 65. Conversely, if corners are formed at the outer and inner peripheral edges of the cut surface 65, the possibility of stress concentration at these corners leading to defects such as cracking is also taken into consideration. However, according to the above structure, since such corners are not formed, the possibility of stress concentration is significantly reduced. As a result, the reciprocating pump 100 can be used stably and continuously for a longer period of time.

[0075] <Second Variation>

[0076] As a second variant of the low-pressure side ring 60, it can also be adopted Figure 9 The structure shown is illustrated. In the example shown, the cut surface 65 is a concave curved surface that is recessed towards the high-pressure side. This cut surface 65 can be an arc shape or a curved surface with gradually changing curvature. Furthermore, this variation can be applied to any combination of the first to third embodiments described above.

[0077] According to the above structure, since the cut surface 65 is a concave curved surface that is recessed towards the high-pressure region V1, stress concentration on the cut surface 65 can be avoided. Conversely, if corners are formed at the outer and inner peripheral edges of the cut surface 65, the possibility of stress concentration at these corners leading to defects such as cracking is also taken into consideration. However, according to the above structure, since such corners are not formed, the possibility of stress concentration can be significantly reduced. As a result, the reciprocating pump 100 can be used stably and continuously for a longer period of time.

[0078] <Third Variation>

[0079] As a third variant of the low-pressure side ring 60, it is also possible to adopt Figure 10The structure shown is illustrated. In the example shown, the cut surface 65 has a first surface 67 and a second surface 68. The first surface 67 faces the outer peripheral side. The second surface 68 extends from the high-pressure side end edge of the first surface 67 toward the outer peripheral side. As an example, the first surface 67 and the second surface 68 are orthogonal to each other in a cross-sectional view including axis O. Furthermore, this variation can be applied to any combination of the first to third embodiments described above.

[0080] According to the above structure, the cut surface 65 has a rectangular cross-sectional shape by having a first surface 67 and a second surface 68. This improves the visibility of the cut surface 65 itself. That is, it is easy to visually confirm which surface has the cut surface 65. Therefore, it enables more efficient and rapid assembly operations. Furthermore, it reduces the possibility of malfunctions in the final product due to assembly errors.

[0081] <Other variations>

[0082] Furthermore, in the embodiments described above, an example of using a reciprocating pump 100 for compressing liquid hydrogen has been described. However, the reciprocating pump 100 can also be applied to the compression of cryogenic liquefied gases such as liquefied carbon dioxide, liquefied natural gas, and liquefied petroleum gas.

[0083] <Postscript>

[0084] The reciprocating pump 100 described in each embodiment is as follows.

[0085] (1) The reciprocating pump 100 of the first type includes: a pump body 9 having a piston 1 for compressing liquid and a cylinder 2 covering the piston 1 from the outside; a drive unit 3 for reciprocating the piston 1 relative to the cylinder 2 in the reciprocating direction; a piston ring 12 disposed in the gap between the piston 1 and the cylinder 2, having an annular groove 30 formed on the outer peripheral surface of the piston 1 that is recessed toward the inner peripheral side and extends in the circumferential direction on the outer peripheral surface, the space inside the cylinder 2 being divided by the piston ring 12 into a high-pressure region V1 for the compressed liquid to flow through and a low-pressure region V2 with an internal pressure lower than that of the high-pressure region V1, the piston ring 12 having a high-pressure side ring 50 disposed on the high-pressure region V1 side of the annular groove 30 and a low-pressure side ring 60 disposed on the low-pressure region V2 side of the annular groove 30 relative to the high-pressure side ring 50, and having a cut surface 65 formed on the outer peripheral side of the surface of the low-pressure side ring 60 that moves backward toward the high-pressure region V1 side.

[0086] According to the above structure, a notch 65 is pre-formed in the outer peripheral region, which is prone to deformation under pressure. Therefore, even when high pressure is applied to the outer peripheral edge, deformation towards the low-pressure region V2 is allowed to a certain extent, corresponding to the amount of the notch. This reduces the likelihood that a portion of the low-pressure side ring 60 will be pressed into the gap between the piston 1 and the cylinder 2.

[0087] (2) The second type of reciprocating pump 100 is based on the reciprocating pump 100 in (1), wherein the cut surface 65 extends from the low pressure region V2 side toward the high pressure region V1 side as it moves from the inner peripheral side toward the outer peripheral side.

[0088] According to the above structure, a notch 65 is pre-formed in the outer peripheral region, which is prone to deformation under pressure. Therefore, even when high pressure is applied to the outer peripheral edge, deformation towards the low-pressure region V2 is allowed to a certain extent, corresponding to the amount of the notch. This reduces the likelihood that a portion of the low-pressure side ring 60 will be pressed into the gap between the piston 1 and the cylinder 2.

[0089] (3) The third-party reciprocating pump 100 is based on the reciprocating pump 100 in (1), wherein the cut surface 65 is a convex curved surface protruding toward the low-pressure region V2.

[0090] According to the above structure, the cut surface 65 is a convex curved surface that protrudes towards the low-pressure region V2, thus avoiding stress concentration at the cut surface 65.

[0091] (4) The reciprocating pump 100 of the fourth method is based on the reciprocating pump 100 of (1), wherein the cut surface 65 is a concave curved surface that is recessed toward the high pressure region V1.

[0092] According to the above structure, since the cut surface 65 is a concave curved surface that is recessed toward the high-pressure region V1, stress concentration on the cut surface 65 can be avoided.

[0093] (5) The fifth type of reciprocating pump 100 is based on the reciprocating pump 100 of (1), wherein the cut surface 65 has a first surface 67 facing the outer peripheral side and a second surface 68 extending from the end edge of the high pressure region V1 side of the first surface 67 toward the outer peripheral side.

[0094] According to the above structure, the cut surface 65 has a rectangular cross-sectional shape by having a first surface 67 and a second surface 68. This improves the visibility of the cut surface 65 itself. Therefore, it enables more efficient and rapid assembly operations.

[0095] (6) The reciprocating pump 100 of the sixth mode is based on the reciprocating pump 100 of any of the first to fifth modes, wherein the radial dimension of the cut surface 65 is set in the range of above the radial dimension of the gap and less than twice the radial dimension of the gap.

[0096] Based on the above structure, it is possible to have a margin of safety to avoid deformation of the low-pressure side ring 60 and the resulting decrease in sealing performance.

[0097] (7) The reciprocating pump 100 of the seventh method is based on the reciprocating pump 100 of any of the first to sixth methods, wherein the dimension of the high-pressure side ring 50 in the reciprocating direction is set to be more than 1.5 times the dimension of the low-pressure side ring 60 in the reciprocating direction.

[0098] Based on the above structure, the dimensions of the high-pressure side ring 50 in the reciprocating direction are set to be larger than those of the low-pressure side ring 60, thus increasing rigidity. This makes deformation at the joint P less likely to occur.

[0099] (8) The reciprocating pump 100 of the eighth type is based on the reciprocating pump 100 of any of the first to seventh types, and a second cut surface 66 is formed on the outer peripheral side of the low-pressure side ring 60 facing the high-pressure region V1 side.

[0100] According to the above structure, in addition to the cut surface 65 formed on the surface facing the low-pressure region V2, a second cut surface 66 is also formed on the surface facing the low-pressure region V2. Therefore, in addition to avoiding a decrease in sealing performance, the assembly direction of the low-pressure side ring 60 does not need to be specified during assembly.

[0101] Industrial availability

[0102] According to the present invention, a reciprocating pump with piston rings that provide higher sealing performance can be provided.

[0103] Explanation of reference numerals in the attached figures

[0104] 1: Piston

[0105] 2: Cylinder

[0106] 3: Drive unit

[0107] 4: Outer shell

[0108] 5: Check valve

[0109] 6: Drainage piping

[0110] 7: Discharge valve

[0111] 9: Pump body

[0112] 10: Piston Body

[0113] 11: Wear ring

[0114] 12: Piston rings

[0115] 21: Compression Chamber

[0116] 30: Annular groove

[0117] 31: Bottom wall surface

[0118] 32: Low-pressure sidewall

[0119] 33: High-voltage side wall

[0120] 41: Outer shell body

[0121] 42: Supply Management

[0122] 43: Gas exhaust pipe

[0123] 44: Liquid Storage Chamber

[0124] 50: High-voltage side ring

[0125] 51: First outer peripheral surface

[0126] 52: First contact surface

[0127] 53: First inner circumferential surface

[0128] 54: First base

[0129] 60: Low-pressure side ring

[0130] 61: Second outer peripheral surface

[0131] 62: Second contact surface

[0132] 63: Second inner circumferential surface

[0133] 64: Second bottom surface

[0134] 65: Cut surface

[0135] 66: Second cut surface

[0136] 67: First Page

[0137] 68: Second page

[0138] 70: Support ring

[0139] 80: Spring component

[0140] 100: Reciprocating pump

[0141] h: Opening

[0142] O: Axis

[0143] P: Closed mouth

[0144] V1: High-voltage area

[0145] V2: Low-pressure area

Claims

1. A reciprocating pump, characterized in that, have: The pump body has a piston that compresses liquid and a cylinder that covers the piston from the outside; A drive unit that causes the piston to reciprocate relative to the cylinder in a reciprocating direction; Piston rings, which are disposed in the gap between the piston and the cylinder. An annular groove extending circumferentially and recessed towards the inner circumferential side is formed on the outer circumferential surface of the piston. The space inside the cylinder is divided by the piston rings into a high-pressure region where the compressed liquid flows and a low-pressure region where the internal pressure is lower than that of the high-pressure region. The piston ring has a high-pressure side ring disposed on the high-pressure region side of the annular groove and a low-pressure side ring disposed on the low-pressure region side of the annular groove relative to the high-pressure side ring. A cut surface is formed on the outer periphery of the surface of the low-pressure side ring facing the low-pressure region side.

2. The reciprocating pump according to claim 1, characterized in that, The cut surface extends from the low-pressure region side toward the high-pressure region side as it moves from the inner peripheral side toward the outer peripheral side.

3. The reciprocating pump according to claim 1, characterized in that, The cut surface is a convex curved surface that protrudes towards the low-pressure area.

4. The reciprocating pump according to claim 1, characterized in that, The cut surface is a concave curved surface that is recessed towards the high-pressure area.

5. The reciprocating pump according to claim 1, characterized in that, The cut surface has a first surface facing the outer peripheral side and a second surface extending from the end edge of the high-pressure area side of the first surface toward the outer peripheral side.

6. The reciprocating pump according to any one of claims 1 to 5, characterized in that, The radial dimension of the cut surface is set within a range that is above the radial dimension of the gap and less than twice the radial dimension of the gap.

7. The reciprocating pump according to any one of claims 1 to 5, characterized in that, The dimension of the high-pressure side ring in the reciprocating direction is set to be more than 1.5 times the dimension of the low-pressure side ring in the reciprocating direction.

8. The reciprocating pump according to any one of claims 1 to 5, characterized in that, A second cut surface is formed on the outer peripheral edge of the face of the low-pressure side ring facing the high-pressure area side.

Images