JP2009180090A - Piston ring of pressure boosting pump for low temperature fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piston ring of a pressure boosting pump for a low temperature fluid capable of preventing pump performance from being deteriorated by preventing damage thereto from occurring. <P>SOLUTION: This piston ring comprises a piston ring 21 formed of a low abrasive resin material and a piston ring 22 formed of a high strength resin material. The piston ring 21 is disposed in a ring groove 2 formed on the outer peripheral surface of the piston 2 of the pressure boosting pump for a low temperature fluid on the low pressure side, and the piston ring 22 is disposed on the high pressure side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piston ring, and is particularly suitable for a low-temperature fluid booster pump that compresses and pressurizes a low-temperature fluid.

  Patent Documents 1 and 2 show a booster pump for low-temperature fluid that compresses and pressurizes a low-temperature fluid (for example, liquid hydrogen, liquid nitrogen, liquefied natural gas, etc.) at a low temperature (for example, −253 ° C. to −100 ° C.). Are known.

JP 2006-275025 A JP 2007-1000064 A

  The booster pump for low-temperature fluid is provided with a piston ring on the outer peripheral surface of the piston as in a normal pump. However, in the booster pump for low-temperature fluid, since a low-temperature fluid is targeted, a lubricating oil cannot be used unlike a normal pump, and a piston ring made of a resin material is used. And when using, as shown to Fig.6 (a), (b), the two piston rings 31 and 32 are assembled | attached and used for the mutual opening 31a and 32a in a different position.

  However, in the pressurizing pump for low-temperature fluid, the piston rings 31 and 32 contract due to the low temperature, and the piston rings 31 and 32 are worn because there is no lubricating oil. The mouths 31a and 32a are opened (see FIG. 6B). In that case, in the structure as shown in FIG. 6B, bending stress due to the compression pressure P is generated in the high-pressure side piston ring 32, and the piston ring 32 is broken (see reference numeral 33 in FIG. 6C). ). Due to this breakage, there is a problem that the amount of leakage from the piston ring 32 increases, leading to a decrease in pump performance (see FIG. 6D).

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a piston ring of a booster pump for low-temperature fluid that can prevent breakage and prevent deterioration of pump performance.

The piston ring of the booster pump for low-temperature fluid according to the first invention for solving the above-described problem is
A first piston ring formed from a low wear resin material;
It consists of a second piston ring formed from a high-strength resin material,
In the ring groove formed on the outer peripheral surface of the piston of the booster pump for low temperature fluid, the first piston ring is disposed on the low pressure side, and the second piston ring is disposed on the high pressure side.

The piston ring of the booster pump for low-temperature fluid according to the second invention for solving the above-mentioned problems is
A first piston ring formed from a low wear resin material;
A second piston ring formed of a resin material and embedded with a reinforcing member;
In the ring groove formed on the outer peripheral surface of the piston of the booster pump for low temperature fluid, the first piston ring is disposed on the low pressure side, and the second piston ring is disposed on the high pressure side.

The piston ring of the booster pump for low temperature fluid according to the third invention for solving the above-mentioned problems is
A first piston ring formed from a low wear resin material;
A second piston ring formed from a resin material;
The reinforcing ring is made of a high strength material and has a smaller outer diameter than the first piston ring and the second piston ring,
In the ring groove formed on the outer peripheral surface of the piston of the booster pump for low temperature fluid, the first piston ring is disposed on the low pressure side so as to sandwich the reinforcing ring, and the second piston ring is disposed on the high pressure side. It is arranged.

The piston ring of the booster pump for low-temperature fluid according to the fourth invention for solving the above-described problems is
A first piston ring formed from a low wear resin material;
A second piston ring formed from a resin material;
A T-shaped cross-section support ring formed of a high-strength material and having a protruding portion having a smaller outer diameter than the first piston ring and the second piston ring;
The first piston ring and the second piston ring are incorporated in the support ring so as to sandwich the projecting portion of the support ring, and a ring groove formed on the outer peripheral surface of the piston of the low-temperature fluid booster pump The first piston ring side is disposed on the low pressure side, and the second piston ring side is disposed on the high pressure side.

  According to the first invention, by forming the first piston ring on the low pressure side from the low wear resin material, it is possible to suppress the opening of the abutment due to wear, and in addition, the second piston on the high pressure side. By forming the ring from a high-strength resin material, resistance to bending stress due to compression pressure can be improved. As a result, it is possible to extend the time (life) until the second piston ring on the high pressure side breaks, and to prevent the pump performance from deteriorating.

  According to the second invention, by forming the first piston ring on the low pressure side from the low wear resin material, it is possible to suppress the opening of the abutment due to wear, and in addition, the second piston on the high pressure side. By reinforcing the ring with a reinforcing member, resistance to bending stress due to compression pressure can be improved. As a result, it is possible to extend the time (life) until the second piston ring on the high pressure side breaks, and to prevent the pump performance from deteriorating.

  According to the third invention, by forming the first piston ring on the low pressure side from the low wear resin material, it is possible to suppress the opening of the abutment due to wear, and in addition, the second piston on the high pressure side. By reinforcing the ring with the reinforcing ring, resistance to bending stress due to compression pressure can be improved. As a result, it is possible to extend the time (life) until the second piston ring on the high pressure side breaks, and to prevent the pump performance from deteriorating. Further, the structure can be simplified and the manufacturing process can be simplified as compared with the case of the second invention.

  According to the fourth invention, by forming the first piston ring on the low pressure side from the low wear resin material, it is possible to suppress the opening of the abutment due to wear, and in addition, the second piston on the high pressure side. By reinforcing the ring with the protruding portion of the support ring, resistance to bending stress due to compression pressure can be improved. As a result, it is possible to extend the time (life) until the second piston ring on the high pressure side breaks, and to prevent the pump performance from deteriorating. Further, the first piston ring and the second piston ring can be reliably positioned as compared with the case of the third invention.

  Hereinafter, with reference to FIGS. 1-5, embodiment of the piston ring of the pressure | voltage rise pump for low temperature fluids which concerns on this invention is described.

  FIG. 1 is a schematic longitudinal sectional view of a cryogenic fluid booster pump including a piston ring according to the present invention.

  The booster pump for low-temperature fluid according to the present invention mainly includes a drive unit (not shown) and a pump unit 1 driven by the drive unit. As shown in FIG. 1, the pump unit 1 includes a piston 2, a piston rod 3, and a cylinder block 4.

  The piston 2 is a substantially cylindrical member that is accommodated in a cylinder 5 formed inside the cylinder block 4 so as to be reciprocally movable. A low-temperature fluid (for example, a lower end surface in FIG. 1) is used for the piston 2. , Liquid hydrogen, liquid nitrogen, liquefied natural gas, etc.) are compressed (pressurized). A plurality (three in this embodiment) of ring grooves 6 are formed along the circumferential direction on the outer peripheral surface of the piston 2, that is, the surface facing the inner peripheral surface (cylinder wall) of the cylinder 5. In addition, piston ring units 7 to be described later are disposed in these ring grooves 6.

  The piston rod 3 is a substantially rod-shaped member having a circular cross section, one end of which is connected to the center of the other end surface of the piston 2 and the other end is connected to a power transmission unit of a drive unit (not shown). ing. The power transmission unit linearly reciprocates the piston rod 3 in the vertical direction by the power from the drive source (see the solid line arrow in FIG. 1).

  The cylinder block 4 is a member having a substantially hollow cylindrical cylinder 5 therein. At the bottom surface of the cylinder 5 (the lower surface in FIG. 1), a fluid inlet 8 into which a low-temperature fluid close to an atmospheric pressure flows and a fluid outlet 9 from which a low-temperature fluid compressed by one end surface of the piston 2 flows out. And are provided. Pipes 10 are respectively connected to the fluid inlet 8 and the fluid outlet 9, and check valves are respectively provided in the pipes 10 located near the upstream side of the fluid inlet 8 and the downstream side of the fluid outlet 9. (Check valves) 11 and 12 are provided. A through hole 13 through which the piston rod 3 passes is provided on the upper surface (the upper surface in FIG. 1) of the cylinder 5, and a seal 14 is provided between the piston rod 3 and the through hole 13. .

  With the above configuration, in the booster pump for low-temperature fluid according to the present invention, the piston 2 connected to one end of the piston rod 3 is connected to the cylinder by the piston rod 3 that linearly reciprocates in the vertical direction by the power from the drive source. The low-temperature fluid reciprocating in the cylinder 5 and sucked into the cylinder 5 from the fluid inlet 8 is compressed by one end face of the piston 2 and compressed to a desired pressure (for example, about 40 MPa). It is led out of the cylinder block 4 from the outlet 9.

  As shown in FIGS. 2 (a) to 2 (c), the piston ring unit 7 of the booster pump for low-temperature fluid according to the present invention is composed of two piston rings 21 and 22 made of a resin material as in the prior art. The two piston rings 21 and 22 are assembled with the mating ports 21a and 22a at different positions.

  In this state, the joints 21a and 22b open due to low-temperature shrinkage and wear as in the conventional case, and bending stress due to the compression pressure P is generated in the high-pressure side piston ring 22, and the piston ring 22 It will break. Therefore, in this embodiment, the piston ring unit 7 is composed of a piston ring 21 made of a low wear resin material and a piston ring 22 made of a high strength resin material, and made of a low wear resin material. The piston ring 21 is disposed on the low pressure side, and the piston ring 22 made of a high-strength resin material is disposed on the high pressure side.

  Thus, by forming the low-pressure-side piston ring 21 from a low wear resin material, the opening of the mating hole 21a due to wear is suppressed. In addition, by forming the high-pressure side piston ring 22 from a high-strength resin material, resistance to bending stress due to the compression pressure P is improved. As a result, it is possible to extend the time (life) until the piston ring 22 breaks and prevent the pump performance from deteriorating.

In addition, as a low wear resin material forming the low-pressure side piston ring 21, a desired specific wear amount (by placing a predetermined filler in a fluororesin material (for example, PTFE (polytetrafluoroethylene) or the like) ( Unit load, amount per unit sliding distance), for example, 0.1 × 10 ⁻⁹ [mm ³ / (N · mm)] or less.

  On the other hand, as a high-strength resin material for forming the high-pressure side piston ring 22, a desired high strength (bending) is obtained by putting a predetermined filler into an engineering plastic material (for example, PEEK (polyether ether ketone)). Strength), for example, 250 [MPa] or more at low temperatures.

  FIG. 3 is a view showing another example of the embodiment of the piston ring according to the present invention. In this embodiment, the configuration of the booster pump for low-temperature fluid may be the same as that of the first embodiment (FIG. 1), and therefore, a duplicate description of the booster pump for low-temperature fluid is omitted here.

  As shown in FIGS. 3A to 3C, in this embodiment, the piston ring unit 7 of the low-temperature fluid booster pump is formed of a piston ring 21 formed of a low wear resin material and a resin material. And a piston ring 23 whose strength is reinforced by the reinforcing member 24. The piston rings 21 are made of a low wear resin material by assembling the two piston rings 21 and 23 with the mating ports 21a and 23a at different positions. Is disposed on the low pressure side, and the piston ring 23 reinforced by the reinforcing member 24 is disposed on the high pressure side.

  The reinforcing member 24 is disposed so as to be embedded in the piston ring 23 or in the vicinity of the surface thereof. Further, the reinforcing member 24 may be disposed over the entire circumference of the piston ring 23 or may be disposed in a part of the piston ring 23 so as to correspond to the position of the abutment 21 a of the piston ring 21. By using a metal (for example, brass, stainless steel, or the like) or a high-strength resin material (for example, a PEEK-based material) as the reinforcing member 24, the piston ring 23 can have a desired high strength (bending strength), for example, It can be 250 [MPa] or more at low temperature. Therefore, the high-pressure side piston ring 23 does not need to be formed from a high-strength resin material as in the first embodiment, and may be a low-strength resin material. It may be formed.

  Thus, by forming the low pressure side piston ring 21 from a low wear resin material, it is possible to suppress the opening of the joint 21a due to wear, and the high pressure side piston ring 23 is reinforced by the reinforcing member 24, thereby compressing. Resistance to bending stress due to pressure P is improved. As a result, it is possible to extend the time (life) until the piston ring 23 breaks and to prevent the pump performance from deteriorating.

  FIG. 4 is a view showing still another example of the embodiment of the piston ring according to the present invention. In this embodiment, the configuration of the booster pump for low-temperature fluid may be the same as that of the first embodiment (FIG. 1), and therefore, the redundant description regarding the booster pump for low-temperature fluid is omitted here.

  As shown in FIGS. 4A to 4C, in this embodiment, the piston ring unit 7 of the low-temperature fluid booster pump is formed of a piston ring 21 formed of a low wear resin material and a resin material. It consists of a piston ring 25 and a reinforcing ring 26 sandwiched between the piston ring 21 and the piston ring 25. The mating ports 21a and 25a are placed at different positions, and the reinforcing ring 26 is sandwiched between them. Two piston rings 21 and 25 are assembled, and the piston ring 21 made of a low wear resin material is disposed on the low pressure side, and the piston ring 25 is disposed on the high pressure side.

  The outer diameter of the reinforcing ring 26 is smaller than the outer diameters of the piston ring 21 and the piston ring 25 so as not to contact the inner peripheral surface (cylinder wall) of the cylinder 5. As the reinforcing ring 26, a metal (for example, brass, stainless steel or the like) or a high-strength resin material (for example, a PEEK-based material) can be used in the same manner as the reinforcing member 24 described above. And even if the force by the compression pressure P acts on the piston ring 25, this reinforcement ring 26 plays the role which suppresses a deformation | transformation of the piston ring 25 and prevents breakage. Therefore, the high-pressure side piston ring 25 does not need to be formed from a high-strength resin material as in the first embodiment, and may be a low-strength resin material. It may be formed.

  Thus, by forming the low-pressure side piston ring 21 from a low wear resin material, the opening of the mating port 21a due to wear is suppressed, and the high-pressure side piston ring 25 is reinforced by the reinforcing ring 26, thereby compressing. Resistance to bending stress due to pressure P is improved. As a result, it is possible to extend the time (life) until the piston ring 25 breaks and prevent the pump performance from deteriorating. Further, as compared with the case of the second embodiment, no special processing is required on the piston ring itself, so that the structure of the piston ring unit 7 can be simplified and the manufacturing process can be simplified.

  FIG. 5 is a view showing still another example of the embodiment of the piston ring according to the present invention. In this embodiment, the configuration of the booster pump for low-temperature fluid may be the same as that of the first embodiment (FIG. 1), and therefore, the redundant description regarding the booster pump for low-temperature fluid is omitted here.

  As shown in FIGS. 5A to 5C, in this embodiment, the piston ring unit 7 of the low-temperature fluid booster pump is formed of a piston ring 21 made of a low wear resin material and a resin material. The piston ring 25 is composed of a piston ring 21 and a support ring 27 that supports the piston ring 25. The mating ports 21a and 25a are located at different positions, and the projecting portion 27a of the support ring 27 is sandwiched therebetween. The two piston rings 21 and 25 are assembled to the support ring 27, and the piston ring 21 side made of a low wear resin material is disposed on the low pressure side, and the piston ring 25 side is disposed on the high pressure side.

  The projecting portion 27 a of the support ring 27 is formed so that the outer diameter thereof is smaller than the outer diameters of the piston ring 21 and the piston ring 25 so as not to contact the inner peripheral surface (cylinder wall) of the cylinder 5. Further, as the support ring 27, a metal (for example, brass, stainless steel, etc.) or a high-strength resin material (for example, PEEK material) can be used in the same manner as the reinforcing member 24 and the reinforcing ring 26 described above. . And even if the force by compression pressure P acts on the piston ring 25, the protrusion part 27a of this support ring 27 has played the role which suppresses a deformation | transformation of the piston ring 25 and prevents breakage. Therefore, the high-pressure side piston ring 25 does not need to be formed from a high-strength resin material as in the first embodiment, and may be a low-strength resin material. It may be formed.

  Thus, by forming the low-pressure side piston ring 21 from a low wear resin material, the opening of the mating port 21a due to wear is suppressed, and the high-pressure side piston ring 25 is reinforced by the projecting portion 27a of the support ring 27. By doing so, the resistance to the bending stress by the compression pressure P is improved. As a result, it is possible to extend the time (life) until the piston ring 25 breaks and prevent the pump performance from deteriorating. Further, the piston rings 21 and 25 can be reliably positioned as compared with the third embodiment.

  As a form of hydrogen use in the future hydrogen use society, liquid hydrogen is one of the promising candidates because it can be stored at high density. On the other hand, as a hydrogen storage system for hydrogen vehicles such as fuel cell vehicles, there is a high possibility of high-pressure hydrogen. Compared to the case where normal temperature / normal pressure hydrogen gas is compressed to 35 MPa to 70 MPa, liquid hydrogen is compressed to 35 MPa to 70 MPa and vaporized to normal temperature to fill a hydrogen vehicle, which is advantageous in terms of compression power. However, when liquid hydrogen is directly compressed using a booster pump for a low temperature fluid, it is extremely low temperature and the pressure is high, so that as described in [Problems to be solved by the invention] above. The piston ring may be broken. The performance of the piston ring is an extremely important part because it directly affects the pump performance. Therefore, by applying the piston ring according to the present invention described above to a booster pump for a low temperature fluid, not only when compressing a low temperature fluid, but also when compressing cryogenic liquid hydrogen to a high pressure, It is possible to prevent the piston ring from being broken and prevent the pump performance from being lowered.

It is a schematic longitudinal cross-sectional view of the booster pump for low temperature fluid provided with the piston ring which concerns on this invention. It is a figure which shows an example (Example 1) of embodiment of the piston ring which concerns on this invention. It is a figure which shows another example (Example 2) of embodiment of the piston ring which concerns on this invention. It is a figure which shows another example (Example 3) of embodiment of the piston ring which concerns on this invention. It is a figure which shows another example (Example 4) of embodiment of the piston ring which concerns on this invention. It is a figure explaining the problem of the piston ring in the pressure | voltage rise pump for low temperature fluids.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump part 2 Piston 5 Cylinder 6 Ring groove 7 Piston ring unit 21, 22, 23, 25 Piston ring 21a, 22a, 23a, 25a Mouth part 24 Reinforcement member 26 Reinforcement ring 27 Support ring 27a Projection part

Claims (4)

A first piston ring formed from a low wear resin material;
It consists of a second piston ring formed from a high-strength resin material,
In the ring groove formed in the outer peripheral surface of the piston of the booster pump for low-temperature fluid, the first piston ring is disposed on the low pressure side, and the second piston ring is disposed on the high pressure side. Piston ring of fluid booster pump. A first piston ring formed from a low wear resin material;
A second piston ring formed of a resin material and embedded with a reinforcing member;
In the ring groove formed in the outer peripheral surface of the piston of the booster pump for low-temperature fluid, the first piston ring is disposed on the low pressure side, and the second piston ring is disposed on the high pressure side. Piston ring of fluid booster pump. A first piston ring formed from a low wear resin material;
A second piston ring formed from a resin material;
The reinforcing ring is made of a high strength material and has a smaller outer diameter than the first piston ring and the second piston ring,
In the ring groove formed on the outer peripheral surface of the piston of the booster pump for low temperature fluid, the first piston ring is disposed on the low pressure side so as to sandwich the reinforcing ring, and the second piston ring is disposed on the high pressure side. A piston ring of a booster pump for low-temperature fluid, characterized by being arranged. A first piston ring formed from a low wear resin material;
A second piston ring formed from a resin material;
A T-shaped cross-section support ring formed of a high-strength material and having a protruding portion having a smaller outer diameter than the first piston ring and the second piston ring;
The first piston ring and the second piston ring are incorporated in the support ring so as to sandwich the projecting portion of the support ring, and a ring groove formed on the outer peripheral surface of the piston of the low-temperature fluid booster pump The piston ring of the booster pump for low-temperature fluid, wherein the first piston ring side is disposed on the low pressure side and the second piston ring side is disposed on the high pressure side.

Images