Reciprocating pump

Abstract

This reciprocating pump comprises a suction valve for switching the flow state of a liquid. The suction valve has a cylindrical member forming an internal flow path through which the liquid flows and a valve body that can move forward and backward in the axial direction with respect to the cylindrical member. The valve body has a rod section extending in the axial direction and a head section including a sheet surface with a conical surface shape that gradually increases in diameter from one side in the axial direction toward the other side. The cylindrical member has: a valve seat with a conical surface shape that abuts or is separated from the outer peripheral surface of the head section; a valve seat that is provided in a region overlapping the aforementioned valve seat in the axial direction and abuts or separates from the outer peripheral surface of the head section; and a pressure-receiving outer peripheral surface that is fitted to the inner peripheral surface of a cylinder via a gap communicating with a compression chamber on the radially outward side of the valve seats.

Description

Reciprocating Pump

[0001] This application claims priority to Japanese Patent Application No. 2023-203026, filed on November 30, 2023, the contents of which are incorporated herein by reference.

[0002] Reciprocating pumps have been used as devices for compressing liquid hydrogen. This type of pump is capable of pressurizing liquid hydrogen up to approximately 90 MPa, for example. Specifically, a reciprocating pump mainly comprises a piston that reciprocates in the axial direction and a cylinder that surrounds the piston. As the piston reciprocates within the cylinder, the liquid hydrogen is gradually compressed and discharged to the outside. The piston is driven by a drive unit.

[0003] The piston is provided with an intake valve and a discharge valve for supplying and discharging a liquid. An example of this type of valve is disclosed in Patent Document 1 below. In the valve device for a fuel supply system disclosed in Patent Document 1 below, an annular space communicating with a fuel passage constituting a fuel intake path or a fuel discharge path is formed near the periphery of the seat surface of the valve seat, and pressure is introduced into the annular space when the valve is closed. As a result, deformation that attempts to expand the inner diameter of the seat surface radially outward occurs, and deformation that attempts to return the inner diameter of the seat surface radially occurs, thereby canceling out the deformation of the seat portion.

[0004] Patent No. 4241611

[0005] However, in the reciprocating pump for compressing liquid hydrogen as described above, a maximum pressure of approximately 90 MPa is applied to the valve device, and therefore, simply forming the annular space as described above does not sufficiently ensure closure of the seat surface, resulting in a problem of insufficient sealing performance of the valve device.

[0006] The present disclosure provides a reciprocating pump having an intake or discharge valve that exhibits improved sealing performance.

[0007] The reciprocating pump according to the present disclosure comprises a pump body having a piston that compresses a liquid and a cylindrical cylinder centered on an axis and covering the piston from the outside; a drive unit that reciprocates the piston in the axial direction relative to the cylinder; an intake valve and a discharge valve that are provided in the cylinder and switch the flow state of the liquid; the intake valve has a cylindrical member inserted into a accommodating hole formed at one end of the cylinder in the axial direction, and a valve body that can move forward and backward in the axial direction relative to the cylindrical member; the valve body has a rod portion extending in the axial direction, and a head portion that is provided at the other end of the rod portion in the axial direction and has a conical seat surface that gradually increases in diameter from one end to the other end in the axial direction; and the cylindrical member has a conical valve seat that abuts or is spaced apart from the outer peripheral surface of the head portion, and a pressure-receiving outer peripheral surface that is fitted against the inner peripheral surface of the cylinder, radially outward of the valve seat, via a gap that communicates with the compression chamber.

[0008] The reciprocating pump according to the present disclosure includes a pump body having a piston that compresses a liquid and a cylinder that is cylindrical and centered on an axis and that covers the piston from the outside, a drive unit that reciprocates the piston in the axial direction relative to the cylinder, and a discharge valve that is provided in the cylinder and switches the flow state of the liquid, the discharge valve including a second cylindrical member that is provided on the outer circumferential surface of the cylinder and that is cylindrical and centered on a second axis that extends in a direction intersecting the axis and has a second valve seat that is a conical surface and centered on the second axis, a second valve body that is movable back and forth in the second axial direction relative to the second cylindrical member, and a casing that covers the second cylindrical member from the outside. the second valve body has a second rod portion extending in the second axial direction, and a second head portion provided at an end of the second rod portion on the other side in the second axial direction, the second head portion having a conical second seat surface that gradually increases in diameter from one side in the second axial direction to the other side, and a second seal groove that is annular about the second axis and recessed toward the one side in the second axial direction and is capable of accommodating a seal ring is formed on the end face of the second cylindrical member facing the other side in the second axial direction, the second seal groove having a ring shape centered on the second axis and recessed toward the one side in the second axial direction, and an apex angle that the second seat surface of the second valve body forms with the second axis in a cross-sectional view including the second axis is equal to or greater than 130° and equal to or less than 150°.

[0009] According to the present disclosure, it is possible to provide a reciprocating pump having an intake valve or a discharge valve that exhibits higher sealing performance.

[0010] Fig. 1 is a longitudinal cross-sectional view showing the configuration of a reciprocating pump according to an embodiment of the present disclosure; Fig. 2 is an enlarged cross-sectional view of an intake valve according to an embodiment of the present disclosure, showing a state when the valve is closed; Fig. 3 is an enlarged cross-sectional view of an intake valve according to an embodiment of the present disclosure, showing a state when the valve is open; Fig. 4 is an enlarged cross-sectional view of a discharge valve according to an embodiment of the present disclosure, showing a state when the valve is closed; Fig. 5 is an enlarged cross-sectional view of a discharge valve according to an embodiment of the present disclosure, showing a state when the valve is open.

[0011] A reciprocating pump 100 according to an embodiment of the present disclosure will be described below with reference to FIGS. 1 to 5. FIG.

[0012] (Configuration of Reciprocating Pump 100) The reciprocating pump 100 is a device for pressurizing a cryogenic liquid, such as liquid hydrogen, to a high pressure (approximately 90 MPa). As shown in Fig. 1, the reciprocating pump 100 includes a piston 1, a cylinder 2, a drive unit 3, a casing 4, an intake valve 5, a discharge pipe 6, and a discharge valve 7. The piston 1 and the cylinder 2 form a pump body 9.

[0013] (Configuration of piston 1) The piston 1 has a cylindrical piston body 10 that extends in the vertical direction and is centered on the axis O, and a wear ring 11 and a piston ring 12 that are attached to the piston body 10. The radial dimension of the piston body 10 is constant throughout the entire area in the direction of the axis O. The wear ring 11 is provided at the tip of the piston body 10. The wear ring 11 has an annular shape centered on the axis O and is made of a resin material.

[0014] One wear ring 11 is provided at the lower end of the piston body 10, and another wear ring 11 is provided at a distance from the wear ring 11 in the axial direction O. A plurality of (for example, six) piston rings 12 are provided between the pair of wear rings 11 and arranged at intervals in the axial direction O. The wear ring 11 is 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 ring 12 is provided to maintain liquid-tightness and air-tightness between the piston body 10 and the inner circumferential surface of the cylinder 2. The configuration of the piston ring 12 will be described later.

[0015] (Configuration of Cylinder 2) The cylinder 2 is a cylindrical cylinder with a bottom that covers the piston 1 from the outer periphery. The piston 1 is inserted into the cylinder 2 through an opening h at the top of the cylinder 2. The space inside the cylinder 2 below the tip of the piston 1 forms a compression chamber 21. A discharge hole 2c is formed in the inner circumferential surface of the cylinder 2, connecting the compression chamber 21 to the outside (discharge valve 7, described below). An intake valve 5 is provided at the bottom of the cylinder 2 for directing liquid hydrogen into the compression chamber 21. This intake valve 5 is capable of allowing liquid hydrogen to flow only in a direction from the outside of the 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 the cylinder 2 through the intake valve 5.

[0016] A discharge pipe 6 is connected to the side of the cylinder 2 facing the compression chamber 21. The discharge pipe 6 is provided to extract the liquid hydrogen compressed in the compression chamber 21 to the outside of the cylinder 2. A discharge valve 7 is provided on this discharge pipe 6. The discharge valve 7 is capable of circulating liquid hydrogen only in the direction from the compression chamber 21 to the outside when the pressure inside the compression chamber 21 reaches or exceeds a predetermined value.

[0017] (Configuration of Drive Unit 3) The piston 1 described above reciprocates in the direction of the axis O by being given a driving force by the drive unit 3 within the cylinder 2. The drive unit 3 reciprocates the piston 1 within the cylinder 2 by means of an electric motor and a link mechanism (not shown).

[0018] (Configuration of Casing 4) The casing 4 is a container that covers the cylinder 2 from the outside. The casing 4 has a cylindrical casing body 4a with a bottom, a supply pipe 4b, and a gas discharge pipe 4c. The supply pipe 4b is a pipe for guiding liquid hydrogen from an external supply source into the casing body 4a (liquid storage chamber 44). The supply pipe 4b is provided near the bottom surface of the casing body 4a. The gas discharge pipe 4c is provided for discharging vaporized components (gas components) in the liquid storage chamber 44 to the outside. The gas discharge pipe 4c is provided at a position spaced above the supply pipe 4b. The liquid level of the liquid hydrogen in the liquid storage chamber 44 is adjusted so that it is located below the gas discharge pipe 4c. The discharge pipe 6 described above extends to the outside of the casing 4.

[0019] (Configuration of Suction Valve 5) Next, the configuration of the suction valve 5 will be described with reference to Figures 2 and 3. As shown in Figure 2, the discharge valve 7 is provided at one end (i.e., the lower end) of the cylinder 2 in the direction of the axis O. Specifically, an opening (accommodating hole 50) with a circular cross section centered on the axis O is formed at the lower end of the cylinder 2. A cover member 2a is attached to the tip of the cylinder 2 to cover the accommodating hole 50 from below. The cover member 2a is cylindrical and centered on the axis O. The cover member 2a is fastened and fixed to the cylinder 2 from below by bolts 2b. A plurality of bolts 2b are provided at intervals around the circumference. The suction valve 5 is inserted into the accommodating hole 50. The inner circumferential surface of the accommodating hole 50 is formed with a lower inner circumferential surface 51, a recessed inner circumferential surface 52, and a protruding inner circumferential surface 53, extending from one side to the other in the direction of the axis O. The lower inner circumferential surface 51 is cylindrical and centered on the axis O. The lower inner circumferential surface 51 is the inner circumferential surface of the cover member 2a. The recessed inner circumferential surface 52 is connected to the upper side of the lower inner circumferential surface 51. The recessed inner circumferential surface 52 is cylindrical and has a larger inner diameter than the lower inner circumferential surface 51, with the axis O as its center. The protruding inner circumferential surface 53 is connected to the upper side of the recessed inner circumferential surface 52. The protruding inner circumferential surface 53 is cylindrical and protrudes further inward than the recessed inner circumferential surface 52 and the inner circumferential surface of the compression chamber 21. The surface connecting the protruding inner circumferential surface 53 and the recessed inner circumferential surface 52 is an upper step surface 54. The surface connecting the protruding inner circumferential surface 53 and the lower inner circumferential surface 51 is a lower step surface 55.

[0020] The suction valve 5 includes a cylindrical member 30, a valve element 40, a disk member 60, a ring valve 70, an elastic member 80, and a bushing 90. The cylindrical member 30 extends in the axial direction O from the protruding inner circumferential surface 53 to the recessed inner circumferential surface 52. The cylindrical member 30 includes a main body portion 32 having a valve seat 31 and an outer circumferential portion 33 disposed on the outer circumferential side of the main body portion 32. The main body portion 32 is cylindrical and centered on the axis O. The valve seat 31 is formed on the end face of the main body portion 32 on the other side (i.e., the upper side) in the axial direction O. The valve seat 31 has a conical surface shape centered on the axis O. In other words, the diameter of the valve seat 31 gradually increases from one side to the other side in the axial direction O in a cross-sectional view including the axis O. A main body outer circumferential surface 34, which is the outer circumferential surface of the main body portion 32, is clearance-fitted against the protruding inner circumferential surface 53. In other words, a small gap is formed between the main body outer peripheral surface 34 and the protruding inner peripheral surface 53. Therefore, the liquid in the compression chamber flows into this gap. The main body outer peripheral surface 34 is formed in a region overlapping with the valve seat 31 in the direction of the axis O. The main body outer peripheral surface 34 receives pressure from the liquid that has flowed into the gap and constitutes a pressure-receiving outer peripheral surface that offsets the pressure on the valve seat 31. The outer peripheral portion 33 covers the outer peripheral side of the main body portion 32 so as to overlap one end of the main body portion 32 in the direction of the axis O. The outer peripheral portion 33 has a cylindrical shape centered on the axis O. The outer peripheral surface of the outer peripheral portion 33 (outer outer peripheral surface 35) is clearance-fitted against the recessed inner peripheral surface 52. In other words, a small gap is formed between the outer outer peripheral surface 35 and the recessed inner peripheral surface 52.

[0021] The surface of the outer peripheral portion 33 facing the other side in the direction of the axis O is a stepped surface 36. The stepped surface 36 has an annular shape centered on the axis O. A seal groove 37 extending circumferentially about the axis O and recessed toward one side in the direction of the axis O is formed in the stepped surface 36. A seal ring 38 is accommodated in the seal groove 37. The seal ring 38 is provided to prevent leakage of liquid between the upper stepped surface 54 and the stepped surface 36 of the outer peripheral portion 33. Note that the seal groove 37 may be formed on the upper stepped surface 54 side. The seal ring 38 prevents liquid that has flowed into the gap between the main body outer peripheral surface 34 and the protruding inner peripheral surface 53 from penetrating further downward. The seal ring 38 is accommodated in the seal groove 37 in an elastically deformed state by fastening the cover member 2a to the cylinder 2 with bolts 2b.

[0022] The valve body 40 has a rod portion 41 and a head portion 42. The rod portion 41 is rod-shaped and extends in the direction of the axis O. The head portion 42 is integrally formed at the end of the rod portion 41 on the other side in the direction of the axis O. The head portion 42 gradually increases in diameter from one side in the direction of the axis O to the other side. The surface of the head portion 42 facing one side in the direction of the axis O is conical, thereby forming a seat surface 43 that can abut against the valve seat 31 described above.

[0023] In a cross-sectional view including the axis O, the angle that this seat surface 43 makes with respect to the axis O, i.e., the apex angle θ1, is preferably 80° or more and 100° or less. More preferably, the apex angle θ1 is 85° or more and 95° or less. Most preferably, the apex angle θ1 is 90°. Furthermore, in a cross-sectional view including the axis O, the difference between the angle that the seat surface 43 makes with respect to the axis O and the angle that the valve seat 31 makes with respect to the axis O is preferably 0° or more and 1° or less. More preferably, this angle difference is 0° or more and 0.2° or less. Furthermore, it is preferable that the maximum outer diameter of the valve disc 40, i.e., the outer diameter of the head portion 42, is 30% or more and 80% or less of the maximum inner diameter of the cylinder 2. Most preferably, this numerical range is 70%.

[0024] The disk member 60 is provided to support the valve body 40 and the ring valve 70. The disk member 60 has a disk main body 61 and a flange 62. The disk main body 61 is disk-shaped and centered on the axis O. The disk main body 61 has a plurality of communication holes 63 arranged at intervals in the circumferential direction about the axis O. These communication holes 63 are covered from the other side in the direction of the axis O by the annular plate-shaped ring valve 70. Furthermore, a through-hole 64 is formed at the axis O position (center position) of the disk main body 61, through which the rod portion 41 of the valve body 40 is inserted. The flange 62 protrudes toward the outer periphery from an edge on one side in the direction of the axis O of the disk main body 61. The outer periphery of the flange 62 abuts against the recessed inner periphery 52 in the radial direction and against the lower stepped surface 55 in the direction of the axis O.

[0025] A housing groove 65 is formed on the surface of the disk main body 61 facing one side in the axial direction O, surrounding the through-hole 64. The housing groove 65 is a cylindrical hole with a bottom centered on the axial direction O. A coil spring serving as an elastic member 80 for biasing the valve element 40 is housed in the housing groove 65. A bushing 90 is attached to the rod portion 41 of the valve element 40. More specifically, the bushing 90 is a double nut whose relative position in the axial direction O with respect to the rod portion 41 is adjustable. An elastic restoring force is exerted between the bushing 90 and the bottom surface of the housing groove 65, causing the elastic member 80 to expand toward both sides in the axial direction O. As a result, the valve element 40 is biased toward one side (downward) in the axial direction O, and is normally in a closed state. On the other hand, when the piston 1 rises and the internal pressure of the compression chamber 21 decreases, the resulting pressure difference pulls the valve element 40 upward against the elastic force of the elastic member 80. As a result, the intake valve 5 is opened (see FIG. 3).

[0026] (Configuration of Discharge Valve 7) Next, the configuration of the discharge valve 7 will be described with reference to Fig. 4 and Fig. 5. As shown in Fig. 4, the discharge valve 7 has a valve casing 110, a cover member 110a, a second cylindrical member 120, an inner member 151a, an elastic member 131a, a second valve body 130, and a second seal ring 160.

[0027] The valve casing 110 has a cylindrical shape centered on a second axis X extending in a direction intersecting the axis O. An accommodation space 150 is formed inside the valve casing 110 to accommodate the second cylindrical member 120 and the second valve body 130. The accommodation space 150 has a rod accommodation portion 151, a head accommodation portion 152, and a cylindrical member accommodation portion 153, which are arranged in this order from one side to the other side in the direction of the second axis X. The rod accommodation portion 151, the head accommodation portion 152, and the cylindrical member accommodation portion 153 all have a cylindrical shape centered on the second axis X. Of these, the head accommodation portion 152 has the largest inner diameter, and the rod accommodation portion 151 has the smallest inner diameter. The cylindrical member accommodation portion 153 has an intermediate value between these. The head accommodation portion 152 has a discharge hole 152a formed therein for discharging liquid to the discharge pipe 6. The discharge hole 152a extends in a radial direction relative to the second axis X. A cover member 110a is fastened to the other side of the valve casing 110 in the direction of the axis X by bolts 110b. A discharge hole 154 through which liquid flows is formed in the end face of the valve casing 110 on the other side in the direction of the second axis X. In the open state, liquid that flows in through the discharge hole 154 is discharged to the outside through a communication hole 120a formed in a second cylindrical member 120, which will be described later.

[0028] The second cylindrical member 120 is inserted from the cylindrical member accommodating portion 153 to a midpoint of the rod accommodating portion 151. The second cylindrical member 120 has a cylindrical shape centered on the second axis X. A second valve seat 121 is formed on an end surface of the second cylindrical member 120 facing one side in the second axis X direction. The second valve seat 121 has a conical surface shape with a diameter gradually increasing from the other side toward one side in the second axis X direction. A second seal groove 122 extending circumferentially about the second axis X and recessed toward one side in the second axis X direction is formed on the end surface of the second cylindrical member 120 facing the other side in the second axis X direction. A second seal ring 160 is accommodated in the second seal groove 122 in an elastically deformed state when the cover member 110a is pressed against the valve casing 110 by the bolts 110b.

[0029] An internal member 151a is attached to the other end of the second cylindrical member 120 in the direction of the axis X. The internal member 151a is cylindrical with a bottom and centered on the axis X. On the other hand, one end is open in the direction of the axis X, thereby accommodating a second valve body 130 (described later) so that the second valve body 130 can move back and forth in the direction of the axis X. An elastic member 131a is accommodated on the inner circumferential side of the internal member 151a, which biases the second valve body 130 toward one side in the direction of the axis X. The elastic member 131a is a coil spring. A male thread is formed on the outer circumferential surface of the internal member 151a, and is threaded into a female thread formed on the inner circumferential surface of the valve casing 110.

[0030] The second valve body 130 has a second rod portion 131 and a second head portion 132. The second rod portion 131 is rod-shaped and extends along the second axis X. A second head portion 132 is integrally formed at the end of the second rod portion 131 on the other side in the second axis X direction. The second head portion 132 is cylindrical and centered on the second axis X. The second head portion 132 has a larger outer diameter than the second rod portion 131. A second seat surface 133 that can abut against and separate from the second valve seat 121 is formed on the end face of the second head portion 132 on the other side in the second axis X direction. The second seat surface 133 has a conical surface shape by gradually increasing in diameter from the other side in the second axis X direction to one side.

[0031] In a cross-sectional view including the second axis X, the apex angle θ2, which is the angle between the second seat surface 133 and the second axis X, is preferably 130° or greater and 150° or less. More preferably, the apex angle θ2 is 135° or greater and 145° or less. Most preferably, the apex angle θ2 is 138° or greater and 142° or less. That is, the apex angle θ2 is most preferably 140°. Furthermore, in a cross-sectional view including the second axis X, the difference between the angle between the second seat surface 133 and the second axis X and the angle between the second valve seat 121 and the second axis X is preferably 0° or greater and 1° or less. More preferably, this angle difference is 0° or greater and 0.2° or less. Furthermore, the ratio between the outer diameter of the second seat surface 133 and the inner diameter of the second seat surface 133 is preferably 1.2 or greater and 1.3 or less. More preferably, this ratio is 1.22 or greater and 1.28 or less. Most preferably, this ratio is 1.25. Additionally, the ratio of the outer diameter to the inner diameter of the second valve seat 121 is preferably 1.6 or greater and 2.0 or less. More preferably, this ratio is 1.7 or greater and 1.9 or less. Most preferably, this ratio is 1.8.

[0032] (Operation and Effect) When operating the reciprocating pump 100, first, liquid hydrogen is supplied into the cylinder 2 through the supply pipe 4b, and then 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 gradually compressed to a high-pressure state (for example, approximately 90 MPa). The high-pressure liquid hydrogen is then discharged to the outside through the discharge pipe 6.

[0033] Under such high pressures, the suction valve 5 and the discharge valve 7 are also required to have appropriate pressure resistance and sealing performance. For this reason, the present embodiment employs the above-described configurations.

[0034] With the above configuration, the body outer peripheral surface 34, which serves as the pressure-receiving outer peripheral surface, receives pressure from the liquid flowing into the gap, offsetting the pressure on the valve seat 31. Furthermore, the apex angle of 80° to 100° (preferably 90°) creates a condition similar to that of hydrostatic pressure. This suppresses slippage on the seat surface 43. In particular, when the rigidity of the valve disc 40 is relatively lower than that of the valve seat 31, it is important to suppress relative slippage between the two. With the above configuration, the valve seat 31 and the valve disc 40 contact at the same angle of approximately 45°. Therefore, the valve seat 31 and the valve disc 40 can be in uniform contact with each other without any difference in contact angle. This uniformizes the surface pressure and deformation of the valve seat 31, reducing relative slippage and excessive uneven contact.

[0035] According to the above configuration, the difference in angle between the seat surface 43 and the valve seat 31 and the axis O is between 0° and 1°. This causes the seat surface 43 and the valve seat 31 to abut (internal abut) on their inner peripheries. This internal abutment cancels out the pressure of the fluid flowing into the gap of the seat surface 43 from the outer periphery to the inner periphery contact position and a portion of the pressure acting from the downstream side, thereby reducing the total differential pressure acting on the valve disc 40. Therefore, because the surface pressure on the seat surface 43 can be reduced, the possibility of damage even when the valve is repeatedly contacted by opening and closing the valve can be significantly reduced.

[0036] According to the above-described configuration, a stepped surface 36 is further formed on the outer periphery of the cylindrical member 30, and a seal groove 37 capable of accommodating a seal ring 38 is formed in the stepped surface 36. This makes it possible to utilize the pressure acting on the outer periphery of the valve seat 31 to suppress deformation of the hollow cylindrical valve seat 31 that would otherwise open outward. Furthermore, it is not necessary to form an annular groove on the outer periphery of the valve seat 31, as was previously employed. This makes it possible to achieve both a compact suction valve 5 and improved sealing performance.

[0037] According to the above configuration, by setting the maximum outer diameter of the valve element 40 to 80% or less of the maximum inner diameter of the cylinder 2, it is possible to further improve sealing performance while suppressing the occurrence of cavitation (foaming) of the liquid. This also leads to a reduction in dead volume, which leads to a decrease in efficiency.

[0038] According to the above configuration, the position of the bushing 90 in the direction of the axis O can be adjusted, and therefore it is possible to appropriately adjust the lift amount (the amount of movement in the direction of the axis O) of the valve element 40, which is determined by the position of the bushing 90. As a result, by adjusting the valve opening when the valve is open, it is possible to ensure an appropriate flow rate and also to suppress the occurrence of excessive impact force when seated.

[0039] According to the above configuration, a second seal groove 122 having an annular shape centered on the second axis X is formed on the end surface of the second cylindrical member 120 facing the other side in the second axis X direction. The provision of this second seal groove 122 makes it possible to reduce the stress applied to the second cylindrical member 120 when the valve is closed. This ensures stable operation of the discharge valve 7. Furthermore, by accommodating the seal ring 38 in the second seal groove 122, it is possible to ensure sealing performance between the second cylindrical member 120 and the casing 4. Furthermore, because both the second valve body 130 and the second cylindrical member 120 are rigid, they contact each other at an angle of approximately 140°, which is close to that of a flat plate, thereby suppressing the wedge effect and equalizing the surface pressure. Furthermore, surface contact between the two is ensured, preventing increased relative slippage and extreme uneven contact. This further improves the sealing performance of the discharge valve 7.

[0040] According to the above configuration, the angle between the second valve seat 121 and the second seat surface 133 and the second axis X is between 0° and 1°. This results in line contact between the second valve seat 121 and the second seat surface 133. Therefore, instead of a leveled, uniform surface pressure, a line of peak surface pressure is provided. This makes it possible to suppress leakage of liquid between the second valve seat 121 and the second seat surface 133. As a result, the sealing performance of the discharge valve 7 can be further improved.

[0041] According to the above configuration, by setting the ratio of the outer diameter to the inner diameter of the second seat surface 133 to be 1.2 or more and 1.3 or less, it is possible to optimize the rigidity balance of the second valve body 130. This makes it possible to reduce relative slippage between the second valve seat 121 and the second valve body 130. As a result, it is possible to further improve the sealing performance of the discharge valve 7.

[0042] According to the above configuration, the ratio of the outer diameter to the inner diameter of the second valve seat 121 is 1.6 or more and 2.0 or less, thereby optimizing the rigidity balance of the second valve body 130. This makes it possible to reduce relative slippage between the second valve seat 121 and the second valve body 130. As a result, the sealing performance of the discharge valve 7 can be further improved.

[0043] Other Embodiments The above describes the embodiments of the present disclosure. It should be noted that various changes and modifications can be made to the above configuration without departing from the spirit and scope of the present disclosure. For example, in the above embodiment, an example was described in which the reciprocating pump 100 is used to compress liquid hydrogen. However, the reciprocating pump 100 can also be suitably used to compress low-temperature liquefied gases such as liquefied carbon dioxide, liquefied natural gas, and liquefied petroleum gas.

[0044] <Additional Notes> The reciprocating pump 100 described in each embodiment can be understood, for example, as follows.

[0045] (1) A reciprocating pump 100 according to a first aspect includes a pump body 9 having a piston 1 for compressing a liquid and a cylinder 2 that is cylindrical and has an axis O as its center and that covers the piston 1 from the outside, a drive unit 3 that reciprocates the piston 1 relative to the cylinder 2 in the direction of the axis O, and a suction valve 5 and a discharge valve 7 that are provided in the cylinder 2 and switch the flow state of the liquid. The suction valve 5 is a cylindrical member 30 inserted into a receiving hole 50 formed at one end of the cylinder 2 in the direction of the axis O, and a discharge valve 7 that moves relative to the cylindrical member 30 in the direction of the axis O. and a retractable valve body 40, the valve body 40 having a rod portion 41 extending in the direction of the axis O, and a head portion 42 provided at the end of the rod portion 41 on the other side in the direction of the axis O and having a conical seat surface 43 that gradually increases in diameter from one side in the direction of the axis O to the other side, and the cylindrical member 30 having a conical valve seat 31 abutting against or separated from the outer peripheral surface of the head portion 42, and a pressure-receiving outer peripheral surface (main body outer peripheral surface 34) that is fitted radially outside the valve seat 31 against the inner peripheral surface of the cylinder 2 via a gap that communicates with the compression chamber 21.

[0046] According to the above configuration, the cylindrical member 30 has a pressure-receiving outer peripheral surface provided in a region that overlaps with the valve seat 31 in the direction of the axis O. Therefore, deformation of the cylindrical member 30 when the valve is closed is suppressed, and the sealing performance between the valve body 40 and the valve seat 31 can be improved.

[0047] (2) The reciprocating pump 100 according to the second aspect is the reciprocating pump 100 of (1), in which, in a cross-sectional view including the axis O, the apex angle, which is the angle that the seat surface 43 of the valve body 40 makes with respect to the axis O, is greater than or equal to 80° and less than or equal to 100°.

[0048] With the above configuration, the apex angle is between 80° and 100°, both inclusive, so that the seat surface 43 and the valve seat 31 come into contact with each other at the same angle of approximately 45°. This makes the surface pressure and deformation of the valve seat 31 uniform, making it possible to reduce relative slippage and extreme uneven contact.

[0049] (3) The reciprocating pump 100 according to the third aspect is the reciprocating pump 100 of (2), in which, in a cross-sectional view including the axis O, the difference between the angle that the seat surface 43 makes with respect to the axis O and the angle that the valve seat 31 makes with respect to the axis O is greater than or equal to 0° and less than or equal to 1°.

[0050] According to the above configuration, the difference in angle between the seat surface 43 and the valve seat 31 relative to the axis O is equal to or greater than 0° and equal to or less than 1°. Therefore, the sealing performance can be improved and damage due to extreme uneven contact can be suppressed.

[0051] (4) A reciprocating pump 100 according to a fourth aspect is a reciprocating pump 100 according to any one of aspects (1) to (3), wherein the cylindrical member 30 further has a stepped surface 36 extending outward from an edge of the pressure-receiving outer peripheral surface on one side in the direction of the axis O, and the stepped surface 36 has a sealing groove 37 formed therein that is annular about the axis O and recessed toward one side in the direction of the axis O and capable of accommodating a sealing ring 38.

[0052] According to the above-described configuration, a stepped surface 36 is further formed on the outer periphery of the cylindrical member 30, and a seal groove 37 capable of accommodating a seal ring 38 is formed in the stepped surface 36. As a result, by utilizing the pressure acting on the outer periphery of the valve seat 31, it is possible to suppress deformation of the hollow cylindrical valve seat 31 that would otherwise open outward.

[0053] (5) The reciprocating pump 100 according to the fifth aspect is the reciprocating pump 100 according to any one of the aspects (1) to (4), wherein the maximum outer diameter of the valve body 40 is 30% or more and 80% or less of the maximum inner diameter of the cylinder 2.

[0054] According to the above configuration, by setting the maximum outer diameter of the valve body 40 to be between 30% and 80% of the maximum inner diameter of the cylinder 2, the occurrence of cavitation (foaming) of the liquid can be suppressed, thereby contributing to improving the performance of the reciprocating pump 100.

[0055] (6) The reciprocating pump 100 according to the sixth aspect is a reciprocating pump 100 according to any one of aspects (1) to (5), and further includes a bushing 90 provided on the outer periphery of the rod portion 41 and an elastic member 80 that biases the bushing 90 toward one side in the direction of the axis O, and the position of the bushing 90 in the direction of the axis O is configured to be adjustable.

[0056] According to the above configuration, it is possible to adjust the lift amount to an appropriate flow rate according to the operating conditions and to suppress excessive impact loads.

[0057] (7) A reciprocating pump 100 according to a seventh aspect is the reciprocating pump 100 according to any one of the aspects (1) to (6), wherein the discharge valve 7 includes: a second cylindrical member 120 provided alongside the outer circumferential surface of the cylinder 2, the second cylindrical member 120 having a cylindrical shape centered on a second axis X extending in a direction intersecting the axis O and a second valve seat 121 having a conical surface centered on the second axis X; a second valve body 130 movable forward and backward in the second axis X direction relative to the second cylindrical member 120; and a casing 4 covering the second cylindrical member 120 from the outside. The second valve body 130 includes a second rod portion 131 extending in the second axis X direction. and a second head portion 132 provided at an end of the second cylindrical member 120 on the other side in the second axis X direction, the second head portion 132 having a conical second seat surface 133 that gradually increases in diameter from one side in the second axis X direction to the other side, and a second seal groove 122 that is annular about the second axis X and recessed toward one side in the second axis X direction and is capable of accommodating a seal ring 38 is formed on an end face of the second cylindrical member 120 facing the other side in the second axis X direction, and an apex angle that the second seat surface 133 of the second valve body 130 forms with the second axis X is equal to or greater than 130° and is equal to or less than 150° in cross section including the second axis X.

[0058] According to the above configuration, the second cylindrical member 120 has an end face facing the other side in the direction of the second axis X formed with a second seal groove 122 having an annular shape centered on the second axis X. The provision of this second seal groove 122 makes it possible to reduce the stress applied to the second cylindrical member 120 when the valve is closed by the second seal groove 122. This ensures stable operation of the discharge valve 7.

[0059] (8) The reciprocating pump 100 according to an eighth aspect is the reciprocating pump 100 according to (7), wherein, in a cross-sectional view including the second axis X, the difference between the angle that the second seat surface 133 makes with respect to the second axis X and the angle that the second valve seat 121 makes with respect to the second axis X is greater than or equal to 0° and less than or equal to 1°.

[0060] According to the above configuration, it is possible to suppress leakage of liquid through the gap between the second valve seat 121 and the second seat surface 133. As a result, it is possible to further improve the sealing performance of the discharge valve 7.

[0061] (9) A reciprocating pump 100 according to a ninth aspect is the reciprocating pump 100 of (7) or (8), wherein the ratio of the outer diameter of the second seat surface 133 to the inner diameter of the second seat surface 133 is 1.2 or more and 1.3 or less.

[0062] According to the above configuration, by setting the ratio of the outer diameter to the inner diameter of the second seat surface 133 to be 1.2 or more and 1.3 or less, it is possible to optimize the rigidity balance of the second valve body 130. This makes it possible to reduce relative slippage between the second valve seat 121 and the second valve body 130.

[0063] (10) The reciprocating pump 100 according to the tenth aspect is the reciprocating pump 100 according to any one of the aspects (7) to (9), wherein the ratio of the outer diameter of the second valve seat 121 to the inner diameter of the second valve seat 121 is 1.6 or more and 2.0 or less.

[0064] According to the above configuration, the ratio of the outer diameter to the inner diameter of the second valve seat 121 is 1.6 or more and 2.0 or less, thereby optimizing the rigidity balance of the second valve body 130. This makes it possible to reduce relative slippage between the second valve seat 121 and the second valve body 130.

[0065] (11) A reciprocating pump 100 according to a second aspect includes a pump body 9 having a piston 1 that compresses a liquid and a cylinder 2 that is cylindrical and centered on an axis O and that covers the piston 1 from the outside, a drive unit 3 that reciprocates the piston 1 in the direction of the axis O relative to the cylinder 2, and a discharge valve 7 that is provided in the cylinder 2 and switches the flow state of the liquid, and the discharge valve 7 is provided alongside the outer circumferential surface of the cylinder 2 and has a cylindrical second cylindrical member 120 that is centered on a second axis X that extends in a direction intersecting the axis O, a second valve body 130 that is movable forward and backward in the second axis X direction relative to the second cylindrical member 120, and a casing 4 that covers the second cylindrical member 120 from the outside, and The valve element 30 includes a second rod portion 131 extending in the direction of the second axis X, and a second head portion 132 provided at an end of the second rod portion 131 on the other side in the direction of the second axis X. The second head portion 132 has a second seat surface 133 in the shape of a cone that gradually increases in diameter from one side in the direction of the second axis X to the other side in the direction of the second axis X. The second cylindrical member 120 has an end surface facing the other side in the direction of the second axis X formed with a second seal groove 122 that is annular about the second axis X and recessed toward one side in the direction of the second axis X so as to accommodate a seal ring 38. In a cross-sectional view including the second axis X, an apex angle that the second seat surface 133 of the second valve body 130 forms with the second axis X is equal to or greater than 130° and is equal to or less than 150°.

[0066] According to the above configuration, the second cylindrical member 120 has an end face facing the other side in the direction of the second axis X formed with a second seal groove 122 having an annular shape centered on the second axis X. The provision of this second seal groove 122 makes it possible to release stress applied to the second cylindrical member 120 when the valve is closed by the second seal groove 122. This ensures stable operation of the discharge valve 7.

[0067] According to the present disclosure, it is possible to provide a reciprocating pump having an intake valve or a discharge valve that exhibits higher sealing performance.

[0068] DESCRIPTION OF SYMBOLS 1...piston 2...cylinder 3...drive part 4...casing 5...suction valve 6...discharge piping 7...discharge valve 9...pump body 10...piston body 11...wear ring 12...piston ring 21...compression chamber 30...cylindrical member 31...valve seat 32...main body part 33...outer periphery 34...main body outer periphery surface 35...outer outer periphery surface 36...step surface 37...seal groove 38...seal ring 40...valve body 4a...casing main body 41...rod part 4b...supply pipe 42...head part 4c...gas discharge pipe 43...seat surface 44...liquid storage chamber 50...accommodation hole 51...lower inner periphery surface 52...recessed inner periphery surface 53...protruding inner periphery surface 54...upper step surface 55...lower step surface 60...disk member 61...disk main body part 62...flange part 63...communicating hole 64...Through hole 65...Accommodation groove 70...Ring valve 80...Elastic member 90...Bush 100...Reciprocating pump 110...Valve casing 120...Second cylindrical member 121...Second valve seat 122...Second seal groove 130...Second valve body 131...Second rod portion 132...Second head portion 133...Second seat surface 150...Accommodation space 160...Second seal ring 151...Rod accommodating portion 152...Head accommodating portion 153...Cylindrical member accommodating portion 154...Discharge hole 160...Second seal ring h...Opening O...Axis X...Second axis

Claims

a pump body having a piston for compressing liquid, and a cylinder having a cylindrical shape centered on an axis and covering the piston from the outside; a drive unit for reciprocating the piston in the axial direction relative to the cylinder; a suction valve and a discharge valve provided in the cylinder for switching the flow state of the liquid, wherein the suction valve has: a cylindrical member inserted into a receiving hole formed in an end of the cylinder on one side in the axial direction; and a valve body movable forward and backward in the axial direction relative to the cylindrical member, wherein the valve body has a rod portion extending in the axial direction, and a head portion provided at an end of the rod portion on the other side in the axial direction and having a conical seat surface that gradually increases in diameter from one side in the axial direction to the other side, wherein the cylindrical member has: a conical valve seat abutting or separating from an outer circumferential surface of the head portion, and a pressure-receiving outer circumferential surface that is fitted against the inner circumferential surface of the cylinder, radially outward of the valve seat, via a gap that communicates with the compression chamber.

2. A reciprocating pump as set forth in claim 1, wherein the apex angle, which is the angle that the seat surface of the valve body makes with respect to the axis when viewed in a cross section including the axis, is equal to or greater than 80° and equal to or less than 100°.

3. A reciprocating pump as described in claim 2, wherein, in a cross-sectional view including the axis, the difference between the angle that the seat surface makes with respect to the axis and the angle that the valve seat makes with respect to the axis is greater than or equal to 0° and less than or equal to 1°.

4. A reciprocating pump as claimed in any one of claims 1 to 3, wherein the cylindrical member further has a stepped surface which extends outward from an edge of the pressure-receiving outer peripheral surface on one side in the axial direction, and a sealing groove which is annular about the axis and recessed towards one side in the axial direction and capable of accommodating a seal ring is formed on the stepped surface.

5. A reciprocating pump as claimed in any one of claims 1 to 3, wherein the maximum outer diameter of the valve body is between 60% and 80% of the maximum inner diameter of the cylinder.

6. A reciprocating pump as claimed in any one of claims 1 to 3, further comprising: a bush provided on the outer periphery of the rod portion; and an elastic member which biases the bush towards one side in the axial direction, wherein the position of the bush in the axial direction is adjustable.

7. The discharge valve comprises: a second cylindrical member provided on the outer peripheral surface of the cylinder, having a cylindrical shape centered on a second axis extending in a direction intersecting the axis, and having a second valve seat shaped like a cone surface centered on the second axis; a second valve body movable back and forth in the second axial direction relative to the second cylindrical member; and a casing covering the second cylindrical member from the outside; the second valve body comprises a second rod portion extending in the second axial direction, and a second head portion provided at an end of the second rod portion on the other side in the second axial direction, the second valve body having a second seat surface shaped like a cone surface whose diameter gradually increases from one side in the second axial direction to the other side; and a second seal groove is formed on the end surface of the second cylindrical member facing the other side in the second axial direction, the second seal groove being annular about the second axis and recessed toward one side in the second axial direction so as to be capable of accommodating a seal ring; 4. The reciprocating pump according to claim 1, wherein in a cross-sectional view including the second axis, an apex angle that the second seat surface of the second valve body forms with the second axis is greater than or equal to 130° and less than or equal to 150°.

8. A reciprocating pump as described in claim 7, wherein, in a cross-sectional view including the second axis, the difference between an angle that the second seat surface makes with respect to the second axis and an angle that the second valve seat makes with respect to the second axis is greater than or equal to 0° and less than or equal to 1°.

9. A reciprocating pump according to claim 7, wherein the ratio of the outer diameter of said second seat surface to the inner diameter of said second seat surface is 1.2 or more and 1.3 or less.

10. A reciprocating pump as set forth in claim 7, wherein the ratio of the outer diameter of said second valve seat to the inner diameter of said second valve seat is 1.6 or more and 2.0 or less.

11. A pump body having a piston for compressing liquid and a cylinder having a cylindrical shape centered on an axis and covering the piston from the outside, a drive unit for reciprocating the piston in the axial direction relative to the cylinder, and a discharge valve provided in the cylinder for switching the flow state of the liquid, wherein the discharge valve comprises: a cylindrical second cylindrical member provided on the outer circumferential surface of the cylinder and centered on a second axis extending in a direction intersecting the axis, a second valve body movable forward and backward in the second axial direction relative to the second cylindrical member, and a casing covering the second cylindrical member from the outside, wherein the second valve body comprises a second rod portion extending in the second axial direction, and a second head portion provided at an end of the second rod portion on the other side in the second axial direction, the second head portion having a second seat surface shaped like a cone whose diameter gradually increases from one side in the second axial direction to the other side, a second seal groove capable of accommodating a seal ring is formed on an end face of the second cylindrical member facing the other side in the second axial direction, the second seal groove being annular about the second axis and recessed toward one side in the second axial direction, and an apex angle that is an angle that the second seat surface of the second valve body makes with respect to the second axis in a cross-sectional view including the second axis is equal to or greater than 130° and equal to or less than 150°.

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