JP2872341B2 - Compressor sealing device for cryogenic formation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sealing device for a cryogenic forming compressor used in a superconducting magnetic levitation type railway vehicle or the like.

[Conventional technology and its problems]

Generally, in a superconducting magnetic levitation railway, liquid helium is used to operate a superconducting magnet. However, since this liquid helium evaporates with time, it is cooled again and liquefied by a refrigerating device. To further explain this, a current typical on-board refrigeration system employs a Claude cycle system, which comprises five heat exchangers 101 and two expanders 102, as shown in FIG. Each of them is composed of one Joule-Thomson valve JT and a compressor 103. Therefore, the helium gas is pressurized by the compressor 103 and its temperature is sequentially reduced through the heat exchanger 101.On the low temperature side of each heat exchanger 101, a part of the helium gas is introduced into the expander 102. The helium gas is expanded and further cooled to a low temperature, and is adiabatically expanded by a Joule-Thomson valve JT to form liquid helium. Using this liquid helium, the evaporated helium in the cryostat (not shown) of the superconducting magnet 104 is again liquefied.

In addition, such a vehicle-mounted refrigeration apparatus is required to be particularly small and lightweight and to have no impurities in the discharged helium gas.

For this reason, for example, with respect to the above-described increase in temperature and work in the compressor 103, the following compressor with low power consumption, that is, small size and light weight has been proposed (see Japanese Patent Publication No. Sho 63-30507).

According to this proposal, since the helium gas which has been compressed by the piston in the cylinder and has become high temperature and high pressure is cooled by the aftercooler, the compression in the cylinder is adiabatic compression and the temperature rises. Therefore, as the temperature of the helium gas increases, the density decreases, the mass flow decreases, and the extra compression work increases accordingly.

For example, comparing the compression of helium gas at 0 ° C from 1ata to 20ata by adiabatic compression and isothermal compression, the former temperature rises about 600 ° C and the work increases about twice In the case of a compressor having a large capacity, the former requires about six times the power consumption, and the motor becomes larger.

Therefore, according to this proposal, in order to compress the helium gas isothermally, it is proposed that the helium gas being compressed and the refrigerant such as Freon be indirectly heat-exchanged through a wall and cooled strongly. ing.

By the way, although not particularly indicated in the above-mentioned publication, when a refrigerant such as Freon is used, a cooling method by evaporating a liquid refrigerant as usually employed in a small compressor,
That is, a condenser cooling method can be considered.

The inventors of the present invention attempted to perform isothermal compression by indirectly exchanging heat between a refrigerant such as chlorofluorocarbon and helium gas circulated by the condenser cooling method through a wall, and during a normal maintenance period of the condenser. It has been found that the cooling effect is reduced in a much shorter period (eg, 500 hours) than (eg, 10,000 hours).

Therefore, when analyzing such a problem, helium gas and chlorofluorocarbon are separated through the wall, but the helium gas needs to be large in order to cool the helium gas during compression strongly, so that the refrigerant jacket must be large. And CFCs are close to each other, and the walls thereof must be separated from each other by a sealing material. Therefore, high-pressure helium gas gradually penetrates toward Freon through the sealing material,
This inert helium gas collects in the condenser and raises the temperature and pressure inside the condenser, preventing the condensation of Freon.
Therefore, it was found that the cooling effect was reduced.

Therefore, it is conceivable to use this sealing material as a sealing material using multiple metal gaskets or the like.
There is a problem that the compressor is large.

[Means for solving the problem]

Therefore, the present invention has been made to solve such a problem, and the gist of the present invention is to provide a multi-stage reciprocating compressor using helium gas as a working fluid around a cylinder liner and a ring-shaped automatic valve. Over, forming a cooling jacket filled with a liquid-phase refrigerant, communicating with the cooling jacket and a condenser, a compressor that cools using latent heat in a phase change from a liquid phase to a gas phase of the refrigerant, A compressor for forming a cryogenic temperature, wherein a seal material is provided at a portion for isolating the helium gas and the refrigerant, and the helium gas leaked beyond the seal material is discharged to the atmosphere so as not to be mixed with the refrigerant. In the sealing device.

〔Example〕

The configuration of the present invention will be described in detail together with the operation according to an embodiment shown in the accompanying drawings.

1 is a schematic view of an embodiment of the present invention, FIG. 2 is a sectional side view of a main part of the compressor shown in FIG. 1, and FIG.
FIG.

This embodiment is suitable for a refrigeration system for liquid helium for a superconducting magnet in a superconducting magnetic levitation railway vehicle, a so-called linear motor car, and is particularly suitable for an oilless compressor in the refrigeration system.

First, the outline of the present embodiment will be described. As shown in FIG. 1, this compressor is composed of two reciprocating horizontal three-stage compressors A and B arranged in a counter-balanced manner so as to meet the restriction of a height of about 30 cm. This is mounted on a truck under the floor of the vehicle.

That is, the first stage cylinders 2A, 2B of each compressor A, B are horizontally opposed to one crankshaft 1, and the second, third stage cylinders 3A, 4A, 3B, 4B are integrated. In this case, convex pistons 5A and 5B are inserted into the cylinders and are opposed to each other horizontally. The first, second, and third-stage cylinders 2, 3, and 4 are tandemly arranged on the crankshaft 1 driven by one electric motor 6. The first stage is a single double acting type, and the second stage is
The three stages are of a double-acting type, and the phase difference between the crank pins is 180 degrees so that the reciprocating inertia force is always balanced. Also, the phase difference between the adjacent first stage, second and third stage crankpins is 90 degrees. In the compressor of this embodiment, the compressed gas uses helium, the intake pressure is about 1 ata, the discharge pressure is about 20 ata, and the gas flow rate is about 70 Nm ³ / h.

Therefore, the operation of the compressor (only A is described) is performed as follows. The crankshaft 1 is driven by the rotation of the motor 6 via the planetary gear type speed reducer 41,
It rotates at a low speed of 330 rpm, and the first stage piston 7A reciprocates in the first stage cylinder 2. As a result, the helium gas is collected and cooled by the intercooler 8 in the passage 9 and then introduced from the passage 9 into the second stage cylinder 3A. Second
In the third stage cylinder 3A, it is compressed by the convex piston 5a, cooled again by the intercooler 10, and
It is introduced into the stage cylinder 4A. The compressed air is compressed by the convex piston 5b in the third stage cylinder 4A and is introduced into the heat exchanger 101 of the refrigeration system shown in FIG.

Next, the details of this embodiment will be described. FIG. 2 shows only the second and third stage cylinders 3A and 4A shown in FIG. 1, and these cylinders 3A and 4B are integrated with each other. The modified convex piston 5A is inserted. The convex piston 5A is fixed to the tip side of a piston rod 12, and the base of the piston rod 12 is a crosshead (guide piston) 13
It is connected to. The crosshead 13 is connected to a leading end of a connecting rod 15 via a crosshead pin 14. The proximal end of the connecting rod 15 is connected to the crankpin 16 of the crankshaft 1 described above.

These second and third stage cylinders 3A and 4A (and, of course, the first stage cylinder 2A as well) are provided with ordinary ring-shaped automatic valves 17 and 18, respectively. Reference numeral 18 includes a valve seat and a valve receiver.

Further, a diaphragm stopper 19 and a diaphragm 20 are fixed to the base side of the piston rod 12 described above,
The lubricating oil injected into the crosshead 13 and the crankshaft 1 is prevented from entering the second and third stage cylinders 3 and 4. Therefore, a ring of each piston uses a self-lubricating ring (Teflon (trade name) containing carbon).

Further, a ring-shaped undercut 21 is formed on the end surface of the second-stage piston 5a, and a part of the third-stage cylinder 4A is fitted into the undercut 21. In other words, a part of the second and third stage cylinders 3A and 4A is overlapped. As a result, the length of the compressor in the axial direction of the piston rod can be reduced, and the weight of the convex piston 5A can be reduced.

Further, in the compressor of this embodiment, a concave groove is formed on the outer periphery of each cylinder liner, and a cooling jacket filled with a refrigerant such as Freon is formed on the outer periphery of the concave groove. A jacket is formed and these cooling jackets are united.

That is, a large number of concave grooves are formed on the outer periphery of the second stage cylinder 3A.
22 are formed, and these concave grooves 22 are surrounded by a cooling jacket 23. The cooling jacket 23 also surrounds the outer periphery of the second-stage automatic valve 17.

Further, a number of concave grooves 24 are formed on the outer periphery of the third-stage cylinder 4A, and these concave grooves 24 are surrounded by the cooling jacket 25. The cooling jacket 25 is a third-stage automatic valve.
It also surrounds the circumference of 18. These cooling jackets 23,2
5 are communicated with each other through a communication passage 26.
6 eliminates the temperature difference between the cooling jackets 23 and 25 based on the difference between the compression temperatures of the second and third stages, and thus eliminates the pressure difference between the fluorocarbons to prevent the liquid fluorocarbon from biasing.

Further, since the third cylinder 4 is particularly cooled,
The cooling jacket 25 of the stage is branched to cool the cylinder head 27. That is, a cooling passage 28 is provided in the cylinder head 27, and the cooling jacket 25 is connected to the cooling passage 28.
Is communicated to. The cooling passage 28 is formed by covering with a lid 29.

In addition, rising pipes 30, 31 are erected on the cooling jackets 23, 25, respectively.
Of the capacitor 32 communicates with the upper header 33 of the capacitor 32.
A lowering pipe 35 communicates with the lower header 34 of the condenser 32, and the cooling jackets 23, 2 are connected via a receiver tank 36.
5 communicates with the lower side.

The condenser 32 is provided in the air path 37, and a suction fan 38 is provided at an end of the air path 37.

Therefore, the liquid Freon for the refrigerant is sealed except for outside air so that the outer circumferences of the second and third cylinders 3A and 4A and the automatic valves 17 and 18 are immersed. As a result, the cylinder and automatic valve are cooled and maintained at a temperature below about 100 ° C.

This liquid Freon evaporates by receiving compression heat from the cylinder and the automatic valve, and the gas rises up the rising pipes 30, 31 and is introduced into the upper header 33 of the condenser 32. Therefore, the condenser 32 is filled with only Freon gas. Since the condenser 32 is air-cooled by the suction fan 38, the Freon gas is cooled and liquefied. This liquid CFC is dropped and stored in the receiver tank 36 via the descending pipe 35. Therefore, the amount of the evaporated liquid CFC is supplied from the receiver tank 36 to each of the cooling jackets 23 and 25.

In this embodiment, as shown in FIG. 3, the high pressure helium gas in the working chamber 39 is not mixed with the liquid Freon in the cooling jackets 23 and 25.
Inexpensive O-ring seal made of elastomer etc. between 40 and second and third stage cylinders 3A and 4A (hereinafter referred to as cylinder liner) and second and third stage automatic valves 17 and 18 and cylinder liner 3A and 4A Sealing is performed using the material S, and the sealing material S
The helium gas that has permeated beyond that is released to the atmosphere so as not to mix into the liquid Freon.

For example, the working chamber 39 of the second-stage cylinder liner 3A and the cooling jacket 23 on the outer periphery of the automatic valve 17 are sealed by two seal materials S1 and S2, of which the seal material S1 is a helium seal. , And S2 seals Freon. Then, a groove c is formed between these sealing materials S1 and S2, and this groove c is released to the atmosphere through a through hole d. Therefore, the helium gas that has permeated the sealant S1 flows into the groove c and is released to the atmosphere through the through hole d, so that it does not enter the Freon of the cooling jacket 23.
As a result, inexpensive sealing materials S1 and S2 can be used, and a space for using multiple metal gaskets is not required.

Here, helium gas is sealed in the undercut 21, and two seals S1 and S2 are interposed between the undercut 21 and the cooling jackets 23 and 25.
A groove c is also formed between S2. Also, the cooling jackets 23, 25 and the atmosphere are sealed with a sealing material S3,
Freon leaked beyond the seal member S3 are released to the atmosphere through the clearance d _1, it does not reduce the purity degree not mixed into the helium gas.

Although the description has been made with reference to the refrigerant CFC of the present embodiment, the present invention is not limited to this, and pure water, alcohol, propane, or the like may be used.

〔The invention's effect〕

According to the present invention, since the cooling jacket is formed large over the cylinder liner and the automatic valve, it is possible not only to cool the helium gas during compression and perform isothermal compression, but also to downsize the drive source of the compressor. The large cooling jacket must be separated from the helium gas through the seal material, but in this case, the helium gas leaks beyond the seal material and is released to the atmosphere, so that it does not mix with the refrigerant. Therefore, the refrigerant is not prevented from being condensed by the helium gas in the condenser. Therefore, the efficiency of the condenser cooling system is not reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of the present invention, FIG. 2 is a sectional side view of a main part of the compressor shown in FIG. 1, FIG. 3 is a detailed view of a part P in FIG. 2, and FIG. FIG. 1 is a schematic view of a refrigeration system for use. 3A, 4A …… Cylinder (liner), 17,18 …… Automatic valve, 23,2
5: cooling jacket, S: sealing material, c: groove, d
... Drill holes.

Claims (1)

(57) [Claims] 1. A cooling jacket filled with a liquid-phase refrigerant is formed around a cylinder liner of a multi-stage reciprocating compressor using helium gas as a working fluid and an outer periphery of a ring-shaped automatic valve, and the cooling jacket and a condenser are formed. Communicate,
In a compressor that cools using a latent heat in a phase change from a liquid phase to a gas phase of the refrigerant, a seal material is provided at a portion that separates the helium gas and the refrigerant, and leakage occurs beyond the seal material. A sealing device for a compressor for forming a cryogenic temperature, wherein the helium gas is discharged to the atmosphere without being mixed into a refrigerant.