JP4031807B2 - Booster pump for cryogenic fluid - Google Patents

Description

  The present invention relates to a low-temperature fluid booster pump that compresses and pressurizes a low-temperature fluid.

2. Description of the Related Art Conventionally, a piston type pump having a piston ring in a piston head is known as a low pressure fluid pressure pump that compresses and pressurizes a low temperature (0 ° C. or lower) fluid (for example, hydrogen) (for example, non-patent Reference 1).
Endo Takuya et al., “New Energy Vehicle”, Sankai-do, January 1995, p. 221-222

In recent years, a booster pump for cryogenic fluid as shown in FIG. 4 has also been proposed.
The booster pump 110 for low-temperature fluid shown in FIG. 4 includes a piston 111, a piston rod 112, a cylinder block 113, a suction valve 114, and a discharge valve 115 as main elements.

The piston 111 is a member having a substantially cylindrical shape that is accommodated in a cylinder (compression chamber) 113a formed inside the cylinder block 113 so as to be reciprocally movable, and has an end surface thereof (a lower end surface in FIG. 4). Cryogenic fluids (eg, liquid hydrogen, liquid nitrogen, liquid oxygen, liquefied carbon dioxide, liquefied natural gas, liquefied propane gas, etc.) can be compressed.
In addition, a ring groove (not shown) is formed on the outer peripheral surface of the piston 111 (that is, the surface facing the inner peripheral surface (cylinder wall) of the cylinder 113a), and resin ( For example, a piston ring (not shown) made of polytetrafluoroethylene is disposed.

The piston rod 112 is a substantially rod-like member having a circular shape in cross section, and one end thereof is connected to the central portion of the other end surface of the piston 111 and the other end is connected to a power transmission unit (not shown). Yes.
The power transmission unit linearly reciprocates the piston rod in a vertical direction with a stroke of, for example, 30 to 40 mm by power from a drive source (not shown). A sealing mechanism for gasified low-temperature fluid in the piston rod is provided. Contains.

The cylinder block 113 is a member having a substantially hollow cylindrical cylinder 113a therein. One end (lower end in FIG. 4) of the cylinder block 113 is an opening, and a suction valve 114 is provided in the opening.
Further, a fluid outlet 116 through which a low-temperature fluid compressed by the one end surface of the piston 111 (for example, pressurized to about 30 to 40 MPa) flows out to the side surface (for example, the right surface in FIG. 4) of the cylinder block 113. A discharge valve (check valve) 115 is provided downstream of the fluid outlet 116. The discharge valve 115 is opened when a fluid pressure higher than or equal to a predetermined pressure is applied (applied), and is closed when the fluid pressure is lower than the predetermined pressure. For example, the discharge valve 115 includes a ball 115a and a spring 115b. is there.

The intake valve 114 is configured with a valve body 117 and a valve casing 119 as main elements.
The valve body 117 includes a cylindrical rod 120 and a substantially truncated cone-shaped head 121 which is provided on one end side of the rod 120 and whose diameter increases as the distance from the rod 120 increases. A flat one end surface (upper end surface in FIG. 4) 121a formed on the front end side of the head 121 is a pressure receiving surface against which a low-temperature fluid compressed by one end surface of the piston 111 is pressed. Further, the other end surface (lower end surface in FIG. 4) 121b of the head 121 is formed to be parallel to the one end surface 121a (that is, the thickness of the head 121 is constant).
On the other hand, a valve seat 113c that coincides with the seat surface 121c of the head 121 is formed at a portion (location) of the cylinder block 113 facing the one end surface of the piston 111, and the seat surface 121c is seated on the valve seat 113c. When this is done, the communication state between the recess 113d and the cylinder 113a is cut off.

  The other end portion of the rod 120 (the lower end portion in FIG. 4) is formed with a screw portion 120 a that is screwed with a screw portion (not shown) of the nut 122, and the other end portion of the rod 120. A spring receiving member 123 is provided between the nut 122 and the nut 122.

The valve casing 119 is a member having a substantially convex shape in cross section, and a plurality of (for example, six) fluid inlets 119a are provided along the circumferential direction on the outer peripheral portion thereof in the plate thickness direction (up and down in FIG. 4). Direction).
In addition, a recess 119b that slidably accommodates the rod 120 is formed in the center portion of the valve casing 119 in the plate thickness direction (vertical direction in FIG. 4).

The other end (the lower end in FIG. 4) of the recess 119b is a spring receiving portion 119c having an inner diameter larger than the inner diameter of the recess 119b. A spring (biasing member) 125 is disposed between the spring receiving portion 119 c and the spring receiving member 123. The spring 125 biases the valve body 117 in the closing direction (ie, the downward direction in FIG. 4), and increases the biasing force of the spring 125 by tightening the nut 122 toward the piston 111. In addition, the biasing force of the spring 125 can be reduced by loosening the nut 122 to the side opposite to the piston 111 side.
Further, the valve casing 119 is attached (fixed) to one end of the cylinder block 113 via a casing presser 126 configured to be detachable from one end of the cylinder block 113 (in this embodiment, screwed). .

  Although not shown in FIG. 4, the cryogenic fluid booster pump 110 is housed in a heat-insulated vacuum vessel in which the inside is evacuated and in which a radiation shield plate such as a copper plate is disposed. ing. In addition, low temperature fluid is stored (or supplied separately) in the adiabatic vacuum vessel, and low temperature fluid in the adiabatic vacuum vessel is supplied into the cylinder 113a through the fluid inlet 119a. It has become.

However, in the booster pump 110 for low-temperature fluid having such a configuration, the low-temperature fluid that leaks from the cylinder 113a into the recess 113d through the space between the seat surface 121c and the valve seat 113c (leaked) is ( Gasification will occur in the recess 113d (which is in the atmospheric pressure state).
Further, the low-temperature fluid gasified at the bottom of the heat-insulating vacuum container accumulates at the bottom of the low-temperature fluid booster pump 110, that is, inside the fluid inlet 119 a and the casing retainer 126.
These gasified low-temperature fluid flows (supplied) into the cylinder 113a in the next suction step and is compressed by the piston 111. However, because of gasification, the so-called “gas bite” is generated in the cylinder 113a. In addition to the occurrence of “state”, compression heat is generated, and the amount of low-temperature fluid flowing into the cylinder 113a decreases, resulting in a problem that volumetric efficiency decreases.
In the test using the cryogenic fluid booster pump 110, the volumetric efficiency was 50% to 60%.

  The present invention has been made in view of the above circumstances, and can increase the amount of low-temperature fluid flowing into a cylinder (compression chamber) and improve volumetric efficiency. The purpose is to provide.

The present invention employs the following means in order to solve the above problems.
A suction valve of a booster pump for a low-temperature fluid according to the present invention is a suction valve of a booster pump for a low-temperature fluid that compresses a low-temperature fluid in a compression chamber, and communicates a recess formed at one end of a cylinder block with the outside. A valve casing having a fluid inlet and a communication hole; a first valve body configured to block communication between the compression chamber and the recess ; and the fluid inlet provided in the recess. And a second valve body configured to be able to block the communication state between the inside of the recess and the fluid inlet while maintaining the state of communication between the inside of the recess and the outside. ing.
According to such a suction valve of the low-temperature fluid booster pump, the first valve body and the second valve body are closed in the compression stroke of the low-temperature fluid booster pump, and the first valve body and the second valve body are closed. Part of the low-temperature fluid (including gasified low-temperature fluid) existing in the space between the body (for example, a recess 13c described later) is discharged to the outside of the booster pump for low-temperature fluid through the communication hole. It is like that.

In the suction valve of the booster pump for low temperature fluid, it is more preferable that a suction pipe is connected to the inlet end of the fluid inlet.
According to such a suction valve of the booster pump for low-temperature fluid, since the suction pipe is connected to the inlet end of the fluid inlet, for example, the low-temperature fluid positioned above the inlet end of the fluid inlet That is, the cryogenic fluid that does not include the gasified cryogenic fluid flows into (is supplied to) the fluid inlet.

The booster pump for low-temperature fluid according to the present invention includes a suction valve for a booster pump for low-temperature fluid that can flow (supply) a low-temperature fluid that has not been gasified into a compression chamber.
According to such a booster pump for low-temperature fluid, the amount of the low-temperature fluid flowing into the compression chamber can be increased, and the volumetric efficiency can be improved.

  According to the present invention, it is possible to increase the amount of the low-temperature fluid flowing into the cylinder (compression chamber) and to improve the volumetric efficiency.

Hereinafter, an embodiment of a booster pump for a low temperature fluid according to the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, a cryogenic fluid booster pump 10 according to this embodiment includes a piston (compression mechanism) 11, a piston rod 12, a cylinder block 13, a suction valve 14, and a discharge valve 15. Is the main element.

The piston 11 is a member having a substantially cylindrical shape that is accommodated in a cylinder (compression chamber) 13a formed inside the cylinder block 13 so as to be reciprocally movable, and has one end surface (the lower side in FIGS. 1 and 2). A cold fluid (for example, liquid hydrogen, liquid nitrogen, liquid oxygen, liquefied carbon dioxide gas, liquefied natural gas, liquefied propane gas, etc.) can be compressed by the end face.
In addition, a ring groove (not shown) is formed on the outer peripheral surface of the piston 11 (that is, the surface facing the inner peripheral surface (cylinder wall) of the cylinder 13a), and resin ( For example, a piston ring (not shown) made of polytetrafluoroethylene is disposed.

The piston rod 12 is a substantially rod-shaped member having a circular shape in cross section, and one end thereof is coupled to the center of the other end surface of the piston 11 and the other end is connected to a power transmission unit (not shown). Yes.
The power transmission unit linearly reciprocates the piston rod in a vertical direction with a stroke of, for example, 2 mm by power from a drive source (not shown).

The cylinder block 13 is a member having a generally hollow cylindrical cylinder 13a therein. One end (lower end in FIGS. 1 and 2) of the cylinder block 13 is an opening, and a suction valve 14 is provided in the opening.
In addition, a fluid from which a low-temperature fluid compressed by one end surface of the piston 11 (for example, pressurized to about 30 to 40 MPa) flows out to the side surface (for example, the right surface in FIGS. 1 and 2) of the cylinder block 13. An outlet 16 is provided, and a discharge valve (check valve) 15 is provided downstream of the fluid outlet 16. The discharge valve 15 is opened when a fluid pressure equal to or higher than a predetermined pressure is applied (applied), and is closed when the fluid pressure is lower than the predetermined pressure. For example, the discharge valve 15 includes a ball 15a and a spring 15b. is there.

The intake valve 14 includes a first valve body (main valve) 17, a second valve body (sub valve) 18, and a valve casing 19 as main elements.
The first valve body 17 includes a columnar rod 20 and a substantially truncated cone-shaped head 21 which is provided on one end side of the rod 20 and whose diameter increases as the distance from the rod 20 increases. The head 21 has a first enlarged diameter portion 21a at the base end (end on the rod 20 side), and a second enlarged diameter portion 21b at the distal end (end on the piston 11 side). . A flat one end surface (upper end surface in FIGS. 1 and 2) 21c formed on the distal end side of the second enlarged diameter portion 21b is a pressure receiving surface against which a low-temperature fluid compressed by one end surface of the piston 11 is pressed. A sheet surface 21d is formed on the side surface of the second enlarged diameter portion 21b along the circumferential direction. The outer peripheral surface of the first enlarged diameter portion 21a is inclined by about 30 ° with respect to the one end surface 21c of the second enlarged diameter portion 21b, and the outer peripheral surface of the second enlarged diameter portion 21b is one end surface. It is inclined about 45 ° with respect to 21c.

  The other end of the rod 20 (the lower end in FIGS. 1 and 2) is formed with a threaded portion 20a that is screwed with a threaded portion (not shown) of the nut 22, and A spring receiving member 23 is provided between the end portion and the nut 22.

As shown in FIG. 3, the second valve body 18 is a ring-shaped (donut-shaped) plate-like member having a circular opening 18a in a plan view at the center, and one end of the cylinder block 13 (see FIG. 1 and FIG. 2 is housed in a recess 13c formed in the lower end portion in FIG. 2, and along the longitudinal direction of the cylinder block 13 (vertical direction in FIGS. 1 and 2) in the recess 13c. It is slidable.
One end surface (the upper end surface in FIGS. 1 and 2) 18b of the second valve body 18 is a pressure-receiving surface against which a low-temperature fluid existing (collected) in the recess 13c is pressed, and the other end surface (FIG. A lower end surface 18 c in FIG. 1 and FIG. 2 is a sheet surface in contact with the sheet member 24.

As shown in FIG. 3, the valve casing 19 is a member having a substantially convex shape in cross section, and a plurality of (for example, six) fluid inlets 19 a along the circumferential direction are provided on the outer peripheral portion of the valve casing 19. It is formed in the thickness direction (vertical direction in FIGS. 1 and 2). In addition, one end surface of the valve casing 19 (the upper end surface in FIGS. 1 and 2) and the outlet end of the fluid inflow port 19a are in contact with the seat surface (the other end surface) 18c of the second valve body 18. Each of the ring-shaped (donut-shaped) sheet members 24 is provided, and when the seat surface 18c is seated on the sheet member 24, all of the outlet ends of the fluid inlet port 19a are completely closed. .
On the other hand, a valve seat 13d that matches the seat surface 21d of the head 21 is formed at a portion (location) of the cylinder block 13 that faces the one end surface of the piston 11, and the seat surface 21d is seated on the valve seat 13d. When it does, the communication state of the recess 13c and the cylinder 13a is interrupted | blocked.

  A recess 19b that slidably accommodates the rod 20 is formed in the center portion of the valve casing 19 in the plate thickness direction (vertical direction in FIGS. 1 and 2). Further, a plurality of (for example, six) communication holes 19c are formed in the plate thickness direction (vertical direction in FIGS. 1 and 2) between the fluid inlet 19a and the recess 19b along the circumferential direction. Has been. These communication holes 19c are passages for discharging the low-temperature fluid existing (accumulated) in the recess 13c to the outside of the low-temperature fluid booster pump 10, and are always open (that is, the second fluid) It is configured so as not to be opened and closed by the valve body 18.

The other end of the recess 19b (the lower end in FIGS. 1 and 2) is a spring receiving portion 19d having an inner diameter larger than the inner diameter of the recess 19b. A spring (biasing member) 25 is disposed between the spring receiving portion 19 d and the spring receiving member 23. The spring 25 biases the first valve body 17 in the closing direction (that is, the downward direction in FIGS. 1 and 2), and the spring 25 is tightened by tightening the nut 22 to the piston 11 side. The urging force of the spring 25 can be reduced by loosening the nut 22 to the side opposite to the piston 11 side.
The valve casing 19 is attached (fixed) to one end portion of the cylinder block 13 via a casing presser 26 and a bolt (not shown).

The inlet end of the fluid inlet 19a is connected to a suction pipe 27 whose free end is located above the inlet end of the fluid inlet 19a and opens upward (vertically). The pipe 27 is attached (fixed) to the casing holder 26 via the suction pipe support member 28.
Although not shown in FIGS. 1 and 2, the cryogenic fluid booster pump 10 according to the present embodiment is evacuated, and a radiation shield plate such as a copper plate is disposed therein. Housed in an insulated vacuum vessel. Further, the low temperature fluid is stored (or supplied separately) in the heat insulating vacuum vessel, and the low temperature fluid in the heat insulating vacuum vessel passes through the suction pipe 27 and the fluid inlet 19a into the cylinder 13a. It comes to be supplied.

  With the above configuration, in the low-temperature fluid booster pump 10 according to the present embodiment, when the piston 11 moves from the bottom dead center to the top dead center side in the suction process, the pressure in the cylinder 13a becomes negative. The first valve element 17 overcomes the urging force of the spring 25 and moves toward the piston 11, the seat surface 21d of the first valve element 17 moves away from the valve seat 13d, and the second valve element 18 The sheet surface 18c is separated from the sheet member 24, and all the outlet ends of the fluid inlet 19a are opened so that the low-temperature fluid in the atmospheric pressure flows into the cylinder 13a (see FIG. 2).

On the other hand, when the piston 11 moves from the top dead center to the bottom dead center in the compression stroke, the pressure in the cylinder 13a becomes positive, and the first valve body 17 moves to the valve seat 13d side. Then, the seat surface 21d of the first valve body 17 is seated on the valve seat 13d, and the seat surface 18c of the second valve body 18 is seated on the seat member 24, and the outlet of the fluid inlet 19a. All of the ends are completely occluded. Thereafter, when the piston 11 further moves toward the head 21, the low-temperature fluid is further compressed between the one end surface of the piston 11 and the one end surface 21c of the head 21, and the low-temperature fluid is applied to a desired pressure. When pressurized (pressurized), the pressurized low-temperature fluid is led out of the cylinder block 13 from the discharge valve 15 through the fluid outlet 16 (see FIG. 1).
At this time, a part of the low-temperature fluid having a pressure higher than the atmospheric pressure existing in the recess 13c passes through the communication hole 19c (that is, the low-temperature fluid booster pump 10). ), That is, in the vicinity of the other end of the rod 20.

  According to the booster pump 10 for low-temperature fluid according to the present embodiment, in the compression stroke, it exists in the space (that is, the recess 13c) between the first diameter-expanded portion 21a of the head 21 and one end surface of the valve casing 19. Since a part of the low-temperature fluid (including the gasified low-temperature fluid) is discharged to the outside of the cylinder block 13 through the communication hole 19c, in the next suction step, the gasified low-temperature fluid is Inflow (supply) into the cylinder 13a can be prevented, the amount of low-temperature fluid flowing into the cylinder 13a can be increased, and volumetric efficiency can be improved.

In addition, since the suction pipe 27 is connected to the inlet end of the fluid inlet 19a, the low-temperature fluid (that is, does not include the gasified cryogenic fluid) positioned above the inlet end of the fluid inlet 19a. Cryogenic fluid) can flow into the cylinder 13a, the amount of the cryogenic fluid flowing into the cylinder 13a can be increased, and the volumetric efficiency can be further improved.
In addition, according to the booster pump 10 for low temperature fluid by this embodiment, it has confirmed that the volumetric efficiency improved to about 80%.

  Furthermore, since the head 21 has a first diameter-expanded portion 21a at the base end portion and is configured to be thick in the thickness direction (vertical direction in FIGS. 1 and 2), the cylinder 13a. It is possible to prevent the head 21 from being distorted (bent) due to the internal pressure, and to maintain the adhesion (air tightness) between the seat surface 21d and the valve seat 13d, thereby improving the pump efficiency. be able to.

  Furthermore, since the casing retainer 26 is configured to be short (thin) in the thickness direction (vertical direction in FIGS. 1 and 2), the gasified low-temperature fluid is collected near the other end of the rod 20. Can be prevented.

  It should be noted that the present invention is not limited to the vertical installation as in the above-described embodiment, but can be horizontal installation, or an upside-down configuration, that is, the piston 11 is positioned below and the intake It is also possible to adopt a form in which the valve 14 is located above. In addition, in the form which turned upside down, the gasified low temperature fluid discharged | emitted to the exterior of the cylinder block 13 through the communicating hole 19c will naturally rise upwards with own buoyancy. Therefore, the suction pipe 27 and the suction pipe support member 28 can be omitted, and the manufacturing cost can be reduced.

  Moreover, the valve seat 13d formed in the part facing the one end surface of the piston 11 of the cylinder block 13 can also be comprised with another member. Thereby, when the valve seat 13d is worn and damaged, it is possible to cope with the problem by replacing only the valve seat 13d, not the entire cylinder block 13.

It is a principal part schematic longitudinal cross-sectional view which shows one Embodiment of the pressure | voltage rise pump for low temperature fluid by this invention, Comprising: It is a figure which shows the state which has a piston in the position of a bottom dead center. It is a principal part schematic longitudinal cross-sectional view which shows one Embodiment of the pressurization pump for low temperature fluid by this invention, Comprising: It is a figure which shows the state which has a piston in the position of a top dead center. It is a disassembled perspective view of the 2nd valve body and valve casing which are shown in FIG. 1 and FIG. It is a principal part schematic longitudinal cross-sectional view which shows the conventional pressure | voltage rise pump for low temperature fluids.

Explanation of symbols

10 Booster pump for low temperature fluid 13a Cylinder (compression chamber)
14 Suction valve 17 First valve body 18 Second valve body 19 Valve casing 19a Fluid inlet 19c Communication hole 27 Suction pipe

Claims (3)

A suction valve of a booster pump for a cryogenic fluid that compresses a cryogenic fluid in a compression chamber,
A valve casing having a fluid inlet and a communication hole for communicating the recess formed at one end of the cylinder block with the outside; and
A first valve body configured to be able to block communication between the compression chamber and the recess ;
Provided in the recess, opens and closes the outlet end of the fluid inlet, and allows the communication between the inside of the recess and the fluid inlet to be blocked while maintaining the state of communication between the inside of the recess and the outside. A suction valve for a cryogenic fluid booster pump, comprising: a second valve body configured .   The suction valve of the booster pump for low-temperature fluid according to claim 1, wherein a suction pipe is connected to an inlet end of the fluid inlet.   3. A cryogenic fluid booster pump comprising the cryogenic fluid booster pump suction valve according to claim 1.

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