JP2862328B2 - Automotive compressor for cryogenic formation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a compressor for forming a cryogenic temperature used in a superconducting magnetic levitation type railway vehicle.

[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, the current representative 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.

And such a vehicle-mounted refrigeration system has low vibration, low noise, and wear resistance of the piston ring (because it is oil-free).
And the like, and the mounting space is extremely limited, so that a conventional cooling or freezing compressor (for example, Japanese Utility Model Publication No. 59-9107) cannot be used.

For example, since the compressor disclosed in the above-mentioned publication is for car coolers, its rotation speed is 1000 rpm during normal operation, its discharge amount is small, and one crankshaft is provided with a pair of opposed cylinders. However, since these pistons always move in the same direction, they form a so-called vibrating device.Thus, although they can be applied to small-capacity compressors, their vibrations cause large-capacity cryogenic formation. It cannot be used for any compressor.

[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 that (1) a low-rotation drive compressor for forming a cryogenic temperature mounted on a superconducting magnetic levitation type railway vehicle. The crank pins of two reciprocating compressors of the same capacity are opposed to one crankshaft so as to have a phase difference of 180 degrees, and this compressor is combined with a double-acting first-stage cylinder and the first cylinder.
A second-stage and a third-stage cylinder in which convex pistons of a double-acting type are inserted in tandem with the first-stage cylinder, respectively. (2) A crank pin of two reciprocating compressors having the same capacity with respect to one crankshaft. Are opposed to each other with a phase difference of 180 degrees, and the compressor is a double-acting type first-stage cylinder, and a convex piston which is arranged in tandem with the first-stage cylinder and is double-acting with each other. And a second-stage and third-stage cylinder into which a third stage cylinder liner is inserted, and a third-stage cylinder liner is inserted into the second-stage and third-stage cylinder liners. In automotive compressor, characterized in that the cylinder liner was partially overlap.

〔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.

FIG. 1 is a schematic view of an embodiment of the present invention, and FIG. 2 is a sectional side view of a main part of the compressor shown in 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 which are opposed to each other so as to meet a restriction of about 40 cm in the height direction. It is arranged and mounted on a truck under the floor of the vehicle.

That is, the first stage cylinders 2A, 2B of the compressors 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. And these first and second and third
The cylinders 2 and 3 and 4 of the stage are arranged in tandem on the crankshaft 1 driven by one electric motor 6. The first stage is of a single double-acting type, the second and third stages are of a double-acting type, and the phase difference between the crankpins 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. By the rotation of the electric motor 6, the crankshaft 1 rotates at a low speed of, for example, 330 rpm via the planetary gear type speed reducer 39, 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. In the second stage cylinder 3A, it is compressed by the convex piston 5A, cooled again by the intercooler 10, and introduced into the third stage cylinder 4A via the passage 11. It 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 distal end of the piston rod 12, and the base of the piston rod 12 is connected to a crosshead (guide piston) 13. This crosshead 13 is a crosshead pin 14
Is connected to the distal end of the connecting rod 15 via a. The base end of the connecting rod 15 is the crank pin 16 of the crankshaft 1 described above.
It is connected to.

Each of the second and third stage cylinders 3A and 4A (and, of course, the first stage cylinder 2A) is provided with a normal ring-shaped automatic valve.
The automatic valves 17, 18 are respectively provided with 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
It does not penetrate into the cylinders 3 and 4 of two or three stages.
Therefore, a ring of each piston uses a self-lubricating ring (carbon-containing ethylene tetrafluoride (Teflon, trade name)).

Here, in this embodiment, particularly, the second stage piston
A ring-shaped undercut 21 is formed on the end face of 5A, and a part of the third-stage cylinder 4A is fitted into the undercut 21. In other words, parts of the second and third stage cylinders 3A and 4A are superposed. 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 of the Freon and prevents the bias of the liquid Freon.

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, liquid Freon for the refrigerant is sealed except for the outside air so that the outer circumferences of the second and third stage cylinders 3A, 4A and the automatic valves 17, 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 37, 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, the first-stage cylinder and the automatic valve are also cooled by the liquid Freon as described above.

In addition, although the refrigerant of the present embodiment was described using Freon,
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 crank pins of two reciprocating compressors having the same capacity are arranged to face each other, the discharge amount is doubled, and a predetermined discharge amount can be obtained even by low-speed driving. The torque fluctuation can be suppressed as much as possible while keeping the height as low as possible.

The first stage cylinder arranged in tandem alone
Since the second and third cylinders are double-acting each other, large-volume discharge gas can be generated while driving at low speed (about 1/3 rotation of ordinary car cooler, home refrigerator and cooler). As a result, in addition to the torque fluctuation suppression described above, the torque fluctuation can be further suppressed, and the noise can be reduced. For example, the noise in the compressor of this embodiment is 7 m at a place 1 m away from the side of the compressor.
It was a low value of 7.5 dB.

Due to the low rotation drive, uneven wear of the self-lubricating piston ring due to its own weight can be reduced.

According to the present invention, since the cutout portion is provided at the boundary end surface of the convex piston constituting the second and third stage cylinders, and the third stage cylinder is inserted into the cutout portion, the weight of the convex piston can be reduced. Not only that, the second and third cylinder axial directions can be shortened, so that the cylinders can be matched to the first cylinder, and the size can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of the present invention, FIG. 2 is a detailed vertical sectional view of a main part of FIG. 1, and FIG. 3 is a schematic view of a general on-board refrigeration system. 1 ... Crankshaft, 2A ... First stage cylinder, 3A, 4A ...
2nd and 3rd stage cylinders, 5A ... Convex piston, 16 ... Crank pin, 21 ... Curve, 39 ... Reducer, A, B ... Compressor.

Claims (2)

(57) [Claims] 1. A low-rotation drive compressor for forming a cryogenic temperature mounted on a superconducting magnetic levitation type railway vehicle, wherein the crankpins of two reciprocating compressors having the same capacity with respect to one crankshaft are rotated by 180 degrees. The compressors are opposed to each other with a phase difference, and the first
A first-stage cylinder and second and third-stage cylinders in which tandemly arranged double-acting convex pistons are inserted in the first-stage cylinder, respectively. An in-vehicle compressor for forming a cryogenic temperature, characterized in that the phase difference between the crank pins of the second stage cylinder is 90 degrees. 2. A reciprocating compressor having two reciprocating compressors of the same capacity is opposed to one crankshaft so as to have a phase difference of 180 degrees. And second and third stage cylinders which are tandemly arranged in the first stage cylinder and into which double-acting convex pistons are inserted, respectively, and furthermore, a boundary end face of the convex piston. An in-vehicle compressor, comprising: an undercut portion, and a third-stage cylinder liner inserted into the undercut portion to partially overlap the second and third-stage cylinder liners.