JP6424369B1 - Piston ring and boost pump for liquefied gas - Google Patents

Abstract

In a piston ring used for a piston of a pressure rising pump for pressurizing and discharging a low temperature liquid, leakage of the low temperature liquid is suppressed and breakage of the piston ring is suppressed. A piston ring includes a first piston ring element having a first joint, and a second piston ring element having a second joint that overlaps with the first piston ring element. The first piston ring element has a first surface that abuts the second piston ring element when the first piston ring element is assembled to the second piston ring element, and a gap between the second joint and the second surface. And, correspondingly, a first protrusion protruding with respect to the first surface. The second piston ring element also has a second protrusion that protrudes with respect to the second surface so as to correspond to a gap between the second surface in contact with the first piston ring element and the first joint. And. [Selected figure] Figure 3

Description

  The present invention relates to a piston ring used for a piston of a pressurizing pump for pressurizing and discharging a low temperature liquid and a pressurizing pump for liquefied gas.

  A pressure rising pump for pressurizing and discharging a low temperature liquid is required to stably press the low temperature liquid to a predetermined pressure and discharge it. For example, in the case of pressurizing a low temperature liquid such as liquefied natural gas at about -162 ° C, the pressure boosting pump is designed in consideration of the thermal contraction of each member due to the low temperature. Moreover, since the boost pump performs a test to determine whether it operates properly at room temperature, the boost pump is designed to operate even in a temperature atmosphere of several tens of degrees Celsius. Therefore, the components of the pressure pump are designed in consideration of thermal contraction at a low temperature lower than several tens of degrees C. to -200 degrees C., for example, a wide temperature range from storage temperature +60 degrees C. to -253 degrees C.

  For example, with regard to the piston ring of a low-temperature fluid pressure booster pump, the piston ring is divided into a first piston ring and a second piston ring for the purpose of preventing breakage and preventing deterioration of pump performance. A combination of the above has been proposed (Patent Document 1).

  The piston ring includes a first piston ring formed of a low wear resin material and a second piston ring formed of a high strength resin material, and the first piston ring side is a low pressure side, the second It is disposed in a ring groove formed on the outer peripheral surface of the piston of the low-temperature fluid pressure booster pump so that the piston ring side of the cylinder is the high pressure side.

JP, 2009-180090, A

  In the above piston ring, the first piston ring and the second piston ring are superimposed on each other and provided in the ring groove, but the relative rotation between the first piston ring and the second piston ring is not restricted. For example, when the piston is retracted to suck the low temperature liquid into the cylinder, the force with which the second piston ring presses and restrains the first piston ring is relaxed, and the first piston ring and the second piston ring The relative rotation between the piston ring and the piston ring is likely to occur. For this reason, even if the first piston ring and the second piston ring are disposed in the ring groove so that the joints do not overlap when the first piston ring and the second piston ring overlap, the joint of the first piston ring and the second piston ring May overlap. In this case, when the piston advances to pressurize the low temperature liquid in the cylinder, a portion of the low temperature liquid flows from the tip of the piston through the gap between the piston and the cylinder to reach the piston ring and passes through the overlapping joint As a result, the cryogenic fluid flows towards the piston base, a so-called cryogenic fluid leak occurs.

  In the corresponding portion of the second piston ring disposed on the high pressure side corresponding to the joint of the first piston ring disposed on the low pressure side, the pressurized low temperature liquid flowing into the gap between the piston and the cylinder High pressure is applied, and this corresponding portion may be bent and deformed at worst because it is not supported by the first piston ring. In particular, since the first piston ring and the second piston ring are made of a resin material, the linear expansion coefficient is high as compared with the metal material, and the thermal contraction is large at a low temperature of -162 ° C. For this reason, the gap between the joint provided in the first piston ring and the second piston ring widens at a low temperature, and as a result, the bending deformation also becomes large and it becomes easy to be broken.

  Therefore, the present invention provides a piston ring that can suppress leakage of low temperature liquid and can suppress breakage of the piston ring in a piston ring used for a piston of a pressure rising pump that pressurizes and discharges low temperature liquid, and further, An object of the present invention is to provide a pressurized pump for liquefied gas using this piston ring.

One aspect of the present invention is a piston ring used for a piston of a pressure rising pump that discharges liquid fuel by pressurizing. The piston ring is
An arc-shaped first piston ring element having a first abutment;
And an arc-shaped second piston ring element having a second joint that is superimposed on the arc shape of the first piston ring element.
A first surface that contacts the second piston ring element when assembling the first arc shape of the first piston ring element to the second arc shape of the second piston ring element; And a first protrusion protruding with respect to the first surface to correspond to a gap of the second joint of the second piston ring element,
The second surface of the second piston ring element that abuts on the first piston ring element when assembling the arc shape of the second piston ring element onto the arc shape of the first piston ring element. And a second protrusion protruding with respect to the second surface to correspond to a gap of the first joint of the first piston ring element,
When the first piston ring element abuts on the second piston ring element, the protruding tip end of the first protrusion has a surface and a surface opposite to the second surface of the second piston ring element. The projection height of the first projection is set to be one .

  When the second piston ring element abuts on the first piston ring element, the projecting end of the second projection has a surface and a surface opposite to the first surface of the first piston ring element. Preferably, the projection height of the second projection is set to be one or to be recessed with respect to the surface opposite to the first surface.

The width along the arc shape of the first protrusion is such that a gap is formed in the second gap when the first protrusion is disposed in the second gap of the second piston ring element, Shorter than the dimension of the clearance along the arc shape of the second joint,
The width along the arc shape of the second protrusion is such that a gap is formed in the first gap when the second protrusion is disposed in the first gap of the first piston ring element, It is preferable that the dimension is shorter than the dimension of the clearance along the arc shape of the first joint.
In this case, the first piston ring element and the second piston ring element are made of polytetrafluoroethylene or a material containing a reinforcing material in polytetrafluoroethylene.
The width along the arc shape of the first protrusion is 40 to 50% of the gap in the second joint,
It is preferable that the width along the said circular arc shape of a said 2nd protrusion part is 40 to 50% of a clearance gap in a said 1st abutment.
Moreover, it is preferable that the protrusion base which touches the said 1st surface in a said 1st protrusion part is comprised with a curved surface. Stress relief can be achieved by configuring the protruding base with the curved surface.

The first projection is provided at a position facing the first joint with respect to the center of the arc shape of the first piston ring element,
It is preferable that the second protrusion be provided at a position facing the second joint with respect to the center of the arc shape of the second piston ring element.
The piston ring expands the first piston ring element and the second piston ring element radially outward from the inside of the arc shape of the first piston ring element and the second piston ring element. Preferably, it comprises a spring member acting as such.

Furthermore, another aspect of the present invention is
A piston provided with the piston ring;
A cylinder having an internal space in which the piston reciprocates;
A liquefied gas pressure-rising pump is provided which sucks, pressurizes and discharges liquefied gas into the internal space by movement of the piston.

  In the piston ring and the pressure pump for liquefied gas described above, it is possible to suppress the leakage of the low temperature liquid in the gap between the piston and the cylinder, and to suppress the breakage of the piston ring.

It is a schematic block diagram of the fuel gas supply apparatus which uses the pressure rising pump for liquefied gas of one Embodiment. It is a sectional view of a pressure rise pump for liquefied gas of one embodiment. It is an appearance perspective view showing an example of a piston ring of one embodiment. It is a figure explaining arrangement of a piston ring of one embodiment. It is a figure explaining the example of the piston ring of one Embodiment.

  Hereinafter, a piston ring and a liquefied gas pressure booster pump according to an embodiment will be described in detail based on the attached drawings.

(Fuel gas supply device)
FIG. 1 is a schematic block diagram of a fuel gas supply device 10 using a liquefied gas pressure booster pump according to an embodiment.

  The fuel gas supply device 10 is a device for injecting a fuel gas obtained by vaporizing a liquid fuel (a fluid of low temperature liquefied gas) into a combustion chamber of the gas combustion engine 28 at a high pressure and supplying the fuel gas. The gas combustion engine 28 is a diesel engine mounted on a ship, and for example, a low-speed diesel engine with a two-stroke cycle can be used.

As shown in FIG. 1, the fuel gas supply device 10 includes a hydraulic oil storage tank 12, a hydraulic pump 14, a hydraulic motor 16, a liquid fuel tank 18, a pressure rising pump 20, a vaporization device 22, and a pressure regulating valve 24. And mainly. In addition to this, the fuel gas supply device 10 has a hydraulic pipe 15, a low pressure liquid fuel supply pipe 19, a high pressure liquid fuel supply pipe 21, and a gas fuel supply pipe 26.
All of these components of the fuel gas supply system 10 are mounted on a ship.
The hydraulic oil storage tank 12 stores hydraulic oil for supplying a hydraulic pressure that drives the hydraulic motor 16.
The liquid fuel tank 18 stores liquid fuel before the fuel gas supplied to the gas combustion engine 28 is vaporized. As the liquid fuel, liquefied natural gas (LNG), liquefied petroleum gas (LPG) or the like can be used. The liquid fuel tank 18 is connected to the low pressure liquid fuel supply pipe 19 and supplies the liquid fuel to the pressure pump 20 via the low pressure liquid fuel supply pipe 19.

  The pressure rising pump 20 has an inlet side connected to the low pressure liquid fuel supply pipe 19 and an outlet side connected to the high pressure liquid fuel supply pipe 21. The pressure rising pump 20 pressurizes the liquid fuel sucked from the liquid fuel tank 18 through the low pressure liquid fuel supply pipe 19 to a constant pressure, and discharges the liquid fuel to the vaporizer 22 through the high pressure liquid fuel supply pipe 21. In the pressure rising pump 20, as described later, the piston 206 reciprocates.

The hydraulic motor 16 is a power source for driving the boost pump 20. For example, it may be a linear actuator (linear motor) that moves forward and backward in the same manner as the piston of the boost pump 20. Further, the rotary motion of the hydraulic motor 16 can be converted into the reciprocating motion of the piston of the pressure pump 20 using a crank (not shown).
The hydraulic motor 16 is driven by the hydraulic pressure supplied through the hydraulic pipe 15 after the hydraulic oil drawn from the hydraulic oil storage tank 12 is pressurized by the hydraulic pump 14. As the hydraulic oil, oil or water-soluble hydraulic oil can be used. The water-soluble hydraulic oil is a hydraulic oil containing water as a main component, and includes, for example, an O / W emulsion, a W / O emulsion, and a polyglycol solution.
In the present embodiment, the hydraulic motor 16 driven by the hydraulic pressure is used, but instead of the hydraulic oil storage tank 12, the hydraulic pump 14, and the hydraulic motor 16, an electric motor may be used. When using an electric motor in a danger area, it is preferable that explosion-proof treatment be performed. Thus, the power source of the pressure rising pump 20 may be any known one and is not particularly limited.

The vaporizer 22 has an inlet side connected to the high pressure liquid fuel supply pipe 21 and an outlet side connected to the gas fuel supply pipe 26. The vaporizer 22 heats and vaporizes the pressurized liquid fuel supplied via the high-pressure liquid fuel supply pipe 21 to turn the liquid fuel into a gas. As a heat source for heating the liquid fuel, for example, the combustion heat of boil-off gas generated in the liquid fuel tank 18 can be used. For example, the liquid fuel may be heated by heat exchange with hot water heated by the combustion heat of the boil-off gas.
A pressure control valve 24 is provided in the fuel gas supply pipe 26, and one end is connected to the vaporization device 22 and the other end is connected to the combustion chamber of the gas combustion engine 28. The fuel gas in which the liquid fuel is vaporized is adjusted to a predetermined pressure (for example, 150 to 400 bar) by the pressure control valve 24 and then supplied to the combustion chamber of the gas combustion engine 28 through the fuel gas supply pipe 26. Ru.
Although not shown in FIG. 1, hydraulic valves (relief valves, check valves, flow control valves, etc.) for adjusting the supply pressure and pressure of hydraulic pressure, liquid fuel and gas are suitably used.

(Boost pump)
FIG. 2 is a cross-sectional view of a pressure rising pump 20 according to an embodiment. The booster pump 20 is connected to the low pressure liquid fuel supply pipe 19 (see FIG. 1) through a liquid fuel supply port 202 provided on the outer periphery of the cylinder 201, and the liquid fuel is drawn into the cylinder liner space of the booster pump 20. The liquid fuel is pushed by the piston 206 to a high pressure, and is discharged from one end of the pressure rising pump 20 through the discharge through hole 216 through the discharge valve of the suction / discharge valve body 208. The piston 206 is driven by the hydraulic motor 16.

  The booster pump 20 includes, as main members, a cylinder 201, a cylinder liner 204, a piston 206, a suction / discharge valve body 208, a top cover 210, and a flange 212.

The piston 206 and the cylinder liner 204 form a cylinder body. The cylinder body has an in-cylinder space defined by the piston 206 and the cylinder liner 204.
The piston 206 is connected to a mechanism such as a linear actuator (not shown) that converts the rotational movement of the hydraulic motor 16 into a reciprocating movement.
The cylinder 201 has a cylindrical shape, is provided with a recess, and the cylinder liner 204 and the suction / discharge valve body 208 are brought into contact with each other, and the cylinder liner 204, the suction / discharge valve body 208, and the top cover 210 are recessed in this order. It is configured to be embedded inside. The wall of the recess, that is, the cylindrical side wall of the cylinder 201 is provided with a supply through hole 214 for supplying liquid fuel. The suction / discharge valve body 208 is abutted against the cylinder liner 204 so that the fluid supply portion connected to the supply through hole 214 is connected to the space in the cylinder of the cylinder liner 204 via the suction valve body. Will be placed. Further, the suction / discharge valve body 208 is provided with a fluid discharge unit for discharging the liquid fuel pressurized by the piston 206 from the space in the cylinder via the discharge valve body. The fluid discharge part is connected to the discharge through hole 216.

  The piston 206 reciprocates the space in the cylinder using the hydraulic motor 16 as a power source. A plurality of ring grooves 220 are provided on the side wall of the piston 206, and each ring groove 220 is provided with a piston ring (not shown in FIG. 2). In the example shown in FIG. 2, although four ring grooves 220 are provided, the number of ring grooves 220 is not limited to four, and may be two, three or five, six, seven, eight, etc. It may be.

(piston ring)
FIG. 3 is an external perspective view of a piston ring 230 according to an embodiment. FIG. 4 is a view for explaining the arrangement of the piston ring 230. As shown in FIG.
Piston ring 230 includes a first piston ring element 232 and a second piston ring element 234.
The first piston ring element 232 is an arc-shaped member provided on the distal end side of the piston 206, and has a first joint 232a.
The second piston ring element 234 is provided on the proximal side of the piston 206 and forms a piston ring 230 in the central axial direction of the first piston ring element 232 so as to overlap the arc shape of the first piston ring element 234 And has a second joint 234a.

The first piston ring element 232 has a first surface 232 c that abuts on the second piston ring element 234 when assembling the arc shape of the first piston ring element 232 into the arc shape of the second piston ring element 234. And a first protrusion 232b protruding with respect to the first surface 232c so as to correspond to the gap of the second joint 234a of the second piston ring element 234.
The second piston ring element 234 has a second surface 234 c that abuts on the first piston ring element 232 when assembling the arc shape of the second piston ring element 234 into the arc shape of the first piston ring element 232. And a second protrusion 234b protruding with respect to the second surface 234c to correspond to the gap of the first joint 232a of the first piston ring element 232.
As shown in FIG. 3, according to one embodiment, the rising bases of the first protrusion 232 b and the second protrusion 234 b are preferably configured as smooth curved surfaces having a radius of curvature.
The material of the first piston ring element 232 and the second piston ring element 234 is not particularly limited, and may be metal, resin or the like. The first piston ring element 232 and the second piston ring element 234 are made of, for example, PTFE (polytetrafluoroethylene). Furthermore, in order to improve strength, it is preferable to include a reinforcing material such as glass fiber in the material.
The first piston ring element 232 and the second piston ring element 234 are attached to the outer periphery of the tension ring 236 (see FIG. 4) to attach the piston ring 230 to the ring groove 220. The tension ring 236 is a spring member which acts to expand the first piston ring element 232 and the second piston ring element 234 radially in the arc shape.

Thus, the first projection 232b is provided on the surface where the first piston ring element 232 faces the second piston ring element 234 so as to correspond to the second joint hole 234a, and the second piston ring element 234 Providing the second protrusion 234 b on the surface facing the first piston ring element 232 to correspond to the first joint port 232 a suppresses leakage of low-temperature liquid fuel and suppresses breakage of the piston ring 230. It is for.
The first projecting portion 232 b and the second projecting portion 234 b restrain relative rotation of the first piston ring element 232 and the second piston ring element 234, so that the first joint 232 a and the second joint 234 a Do not overlap. For this reason, leakage of low temperature liquid fuel can be suppressed.
In addition, since the second projection 234b and the first projection 232b are positioned at the first joint 232a and the second joint 234a, the gap between the first joint 232a and the second joint 234 can be reduced. Since it is possible, it is possible to suppress the leakage of low temperature liquid fuel.
In addition, since the thickness of the first piston ring element 232 is increased by the protruding height of the first protrusion 232 b at the position corresponding to the second joint hole 234 a, the liquid fuel pressurized by the piston 206 is used. Even when a part enters a gap between the piston 206 and the cylinder liner 204 and applies pressure to the piston ring 230, bending deformation hardly occurs and breakage due to bending deformation hardly occurs.

FIG. 5 is a view for explaining an example of a piston ring 230 according to an embodiment. As shown in FIG. 5, the protruding tip of the first protrusion 232 b is the second surface 234 c of the second piston ring element 234 when the first piston ring element 232 abuts on the second piston ring element 234. The projection height of the first projection 232 b is preferably set to be flush with the opposite surface 234 d.
As shown in FIG. 5, when the piston 206 advances to pressurize the liquid fuel, it enters the gap between the piston 206 and the cylinder liner 204 and applies pressure (arrow shown in FIG. 5) to the piston ring 230. Since the surface 234d of the second piston ring element 234 and the projecting tip of the first projection 232b abut on the side wall 220a of the ring groove 220 in a flush state, the second corresponding to the small gap of the second joint 234a The bending deformation of the corresponding portion of the piston ring 232 of 1 is extremely small, and breakage due to the bending deformation is even less likely to occur. This bending deformation corresponds to bending deformation in which one end of the beam receiving the uniform load is fixed and supported and the other end is supported. On the other hand, when the projecting end of the first projecting portion 232b is not flush with the surface 234d and does not abut on the side wall 220a of the ring groove, the corresponding one of the first piston ring 232 corresponding to the small gap of the second joint 234a. The bending deformation of the part corresponds to the bending deformation of the beam supported at both ends under equal load. The bending deformation supported at one end and supported at the other end of the corresponding part of the first piston ring 232 corresponding to the small gap of the second joint 234a is smaller than that of the beam supported at both ends. small. For this reason, durability improves in the form which the surface 234d of the 2nd piston ring element 234 and the protrusion tip of the 1st protrusion part 232b become flush. From this point of view, it is preferable that the protruding height of the first protruding portion 232 b be set so that the protruding end of the first protruding portion 232 b is flush with the surface 234 d of the second piston ring element 234.
Also, when the first piston ring element 232 abuts on the second piston ring element 234, the protruding end of the first protrusion 232b is the surface opposite to the second surface 234c of the second piston ring element 234. The protruding height of the first protrusion 232 b may be set so as to be recessed inward with respect to 234 d. In this case, the plastic deformation of the first piston ring element 232 or the second piston ring element 234 may make the protruding tip of the first protrusion 232b flush with the surface 234d.
Further, according to one embodiment, it is preferable that the corner portions of the first joint 232a and the second joint 234a be chamfered.

  Furthermore, although not shown, the protruding end of the second protrusion 234b is connected to the first surface 232c of the first piston ring element 232 when the second piston ring element 234 abuts on the first piston ring element 232. The protruding end of the second protrusion 234b may be recessed on the surface 232d without being flush with the opposite surface 232d, but the protrusion height of the second protrusion 234b is set to be flush Is also preferred.

The width W along the arc shape of the first protrusion 232 b is such that when the first protrusion 232 b is disposed at the second gap 234 a of the second piston ring element 234, there is a gap in the second gap 234 a. When the second projection 234b is disposed at the first joint 232a of the first piston ring element 232, the clearance is shorter than the clearance dimension L along the arc shape of the second joint 234a. Preferably, the width W of the second protrusion 234b along the arc shape is shorter than the gap dimension L along the arc shape of the first joint 232a.
In a low temperature state, the gap dimension L between the first joint 232a and the second joint 234a is wider and the width W of the first projection 232b and the second projection 234b is smaller than that at ordinary temperature. The gap when 232b and the first protrusion 234b are positioned at the first joint 232a and the second joint 234a is wider than normal temperature, but in this case, if the gap is wide, bending deformation becomes large and it becomes easy to break. Not desirable. However, if the width W of the second protrusion 234b and the first protrusion 232b is as close as possible to the gap dimension L of the first joint 232a and the second joint 234a, the pressure piston can be commissioned in a high temperature state compared to normal temperature. In this case, the first joint 232a and the second joint 232b are narrowed due to the thermal expansion of the members along the arc shape of the first piston ring element 232 and the second piston ring element 234. If there is no space for thermal expansion, the first piston ring element 232 and the second piston ring element 234 are deformed and easily damaged. Therefore, the width W along the arc shape of the first projecting portion 232b and the second projecting portion 234b is a gap dimension L along the arc shape of the second joint 234a and the first joint 232a in consideration of thermal expansion. It is preferable to be shorter than However, the width W is the linear expansion coefficient of the material used for the first piston ring element 232 and the second piston ring element, the size of the first piston ring element 232 and the second piston ring element, and the temperature difference with respect to the design temperature It is determined based on For example, the width W is preferably 40 to 50% of the gap dimension L.

  According to one embodiment, the first protrusion 232 b is provided at a position facing the first joint 232 a with respect to the center of the arc shape of the first piston ring element 232, and the second protrusion 234 b is Preferably, it is provided at a position facing the second joint 234 a with respect to the center of the arc shape of the second piston ring element 234. As a result, in the piston ring 230, since the portions with the first joint 232a and the second joint 234a having low rigidity against bending deformation are at positions farthest from each other, breakage of the piston ring 230 is more difficult to occur. .

  As mentioned above, although the piston ring of this invention and the pressure | voltage rise pump for liquefied gas were demonstrated in detail, this invention is not limited to the said embodiment, Even if it does not deviate from the main point of this invention, various improvement and change are possible. Of course it's good.

DESCRIPTION OF SYMBOLS 10 fuel gas supply apparatus 12 hydraulic fluid storage tank 14 hydraulic pump 15 hydraulic pipe 16 hydraulic motor 18 liquid fuel tank 19 low pressure liquid fuel supply pipe 20 pressure rising pump 21 high pressure liquid fuel supply pipe 22 vaporization device 24 pressure control valve 26 gas fuel supply pipe 28 Gas combustion engine 201 Cylinder 202 Liquid fuel supply port 204 Cylinder liner 206 Piston 208 Intake and discharge valve body 210 Top cover 212 Flange 214 Supply through hole 216 Discharge through hole 218 Liquid fuel supply port 220 Ring groove 220a Side wall 230 Piston ring 232 first piston ring element 232a first joint 232b first projection 232c first surface 232d, 234d surface 234 second piston ring element 234a second joint 234b second projection 234c second surface 236 tension ring

Claims (7)

A piston ring used for a piston of a pressure-rising pump for pressurizing and discharging liquid fuel ,
An arc-shaped first piston ring element having a first abutment;
An arc-shaped second piston ring element having a second joint overlapping with the arc shape of the first piston ring element;
A first surface that contacts the second piston ring element when assembling the first arc shape of the first piston ring element to the second arc shape of the second piston ring element; And a first protrusion protruding with respect to the first surface to correspond to a gap of the second joint of the second piston ring element,
The second surface of the second piston ring element that abuts on the first piston ring element when assembling the arc shape of the second piston ring element onto the arc shape of the first piston ring element. And a second protrusion protruding with respect to the second surface to correspond to a gap of the first joint of the first piston ring element,
When the first piston ring element abuts on the second piston ring element, the protruding tip end of the first protrusion has a surface and a surface opposite to the second surface of the second piston ring element. The piston ring , wherein the projection height of the first projection is set to be one . When the second piston ring element abuts on the first piston ring element, the projecting end of the second projection has a surface and a surface opposite to the first surface of the first piston ring element. so one, or the like in a position which is recessed with respect to the opposite surface to the first surface, the protruding height of the second projecting portion is set, the piston ring according to claim 1 . The width along the arc shape of the first protrusion is such that a gap is formed in the second gap when the first protrusion is disposed in the second gap of the second piston ring element, Shorter than the dimension of the clearance along the arc shape of the second joint,
The width along the arc shape of the second protrusion is such that a gap is formed in the first gap when the second protrusion is disposed in the first gap of the first piston ring element, shorter than the gap size along the arc shape of said first abutment, the piston ring according to claim 1 or 2. The first piston ring element and the second piston ring element are made of polytetrafluoroethylene or a material containing a reinforcing material in polytetrafluoroethylene.
The width along the arc shape of the first protrusion is 40 to 50% of the gap in the second joint,
The piston ring according to claim 3, wherein a width of the second protrusion along the arc shape is 40 to 50% of a gap in the first joint. The first projection is provided at a position facing the first joint with respect to the center of the arc shape of the first piston ring element,
The said 2nd protrusion part is provided in the position facing the said 2nd abutment with respect to the center of the said circular arc shape of the said 2nd piston ring element of any one of Claims 1-4. piston ring. A spring acting to expand the first piston ring element and the second piston ring element radially outward from the inside of the arc shape of the first piston ring element and the second piston ring element The piston ring according to any one of claims 1 to 5, comprising a member. A piston provided with the piston ring according to any one of claims 1 to 6 .
A cylinder having an internal space in which the piston reciprocates;
A liquefied gas pressure-rising pump characterized by suctioning, pressurizing and discharging liquefied gas into the internal space by movement of the piston.

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