JPH0432664A - Cryostatic expander - Google Patents

Abstract

PURPOSE:To obtain the title expander by which the capacity thereof can be prevented from lowering, by a method wherein a first connection line is connected between a low pressure gas pipeline and a surge tank, and a second connection line is connected between a high pressure gas pipeline and the surge tank. CONSTITUTION:For the title expander, a first connection pipeline 11 having a first valve means 11a between a low pressure gas pipeline 7 and a surge tank 9 is connected, and a second connection pipeline 12 having a second valve means 12a between a high pressure gas pipeline 6 and the surge tank 9 is also connected. The information from a temperature-detecting device 14 is inputted to a valve controller 13, and in the process of cooling-down, both of the first and second valve means 11a, 12a are closed, and opening and closing control is repeated only with a high pressure valve 51 and a low pressure valve 52. After a cryogenic condition under which the cooling- down has just finished or approached thereto, in steady operation, the opening of the first valve means 11a is synchronized with the opening of the high pressure valve 51, and the opening of the second valve means 12a is also synchronized with the opening of the low pressure valve 52. As the result of it, even in the steady operation in which a pressure difference is small, a piston 3 is stably operated and the capacity of the title expander can be prevented from lowering.

Description

[Detailed description of the invention] (Industrial field of application) Book! The present invention relates to an improvement of the piston actuation mechanism in a cryogenic expander that obtains cryogenic temperatures at a level of several tens of degrees in absolute temperature.

(Prior Art) Conventionally, as disclosed in Japanese Patent Laid-Open No. 62-252858 and shown in FIG. 3, this type of cryogenic expansion machine has a cylinder (C) equipped with heat stains (A, B) , a piston (P) consisting of a displacer (D) with a regenerator (E, G) and a slack piston (S) that operates it.
is installed inside the cylinder (C), and an injection/discharge passageway (
A high-pressure gas pipe (H) such as helium gas and a low-pressure gas pipe (L) are connected to T) via a switching valve device (W) having high-pressure and low-pressure on-off valves (X, Y), and the slack A counter chamber (R) opposing the action chamber (F) of the piston (S) is filled with a discharge passage (T) and a low pressure gas pipe (L) by a capillary (J) and a bleed (K) through an orifice (0). ), and a surge volume (M) whose inside is set to an intermediate pressure is connected thereto.

In this way, high-pressure gas is introduced into the cylinder (C) by opening only the high-pressure on-off valve (X), and the slack is created by the differential pressure between the working chamber (F), which is at high pressure, and the opposing chamber (R), which is at intermediate pressure. Raise the piston (S) and displacer (D),
Expansion space (U) adjacent to heat station (A, B)
, Z) is filled with introduced gas, and then the low pressure on-off valve (Y)
The slack piston (S) and displacer (D) are lowered by the differential pressure between the low-pressure action chamber (F) and the intermediate-pressure counter chamber (R), and the expanded low-pressure gas is exhausted. That's what I do. By repeating the introduction of high pressure gas and the exhaust of low pressure gas, extremely low temperatures are obtained in the heat station units (A, B).

(Problem to be Solved by the Invention) With the above configuration, the driving force of the piston (P) consisting of the slack piston (S) and the displacer (D) is generated by the high pressure in the action chamber (F) and the opposing chamber (R) when rising. When falling, it is the differential pressure that occurs between the low pressure of the working chamber (F) and the intermediate pressure of the opposing chamber (R).

Therefore, in order to sufficiently drive the piston (P) both when ascending and descending, adjust the bleed (J) and capillary (K) to set the pressure of the surge volume (M) to an approximately intermediate value between high pressure and low pressure. It is considered that it is sufficient to set it to a certain degree.

However, the heat station scene (A, B) has not yet cooled down to an extremely low temperature and the high pressure gas pipe (H)
Regardless of the case where a sufficient pressure difference is secured between the high pressure gas pressure and the low pressure gas pressure flowing to the low pressure gas pipe (L), the heat stage 1 (A, B) is During steady operation, where the pressure is maintained at an extremely low temperature, the pressure difference between the high pressure and the low pressure becomes smaller due to the load reduction, so the differential pressure between the intermediate pressure and the high pressure and the differential pressure between the intermediate pressure and the low pressure are both small. Therefore, there is a problem that sufficient driving force cannot be obtained both during ascending and descending.

On the other hand, if the intermediate pressure of the surge volume (M) is set low so as to ensure a large differential pressure with respect to high pressure, for example, it will improve when rising, but when descending, the differential pressure between low pressure and Since it becomes smaller, there is a problem that its operation becomes even more unstable.

In other words, as in the conventional example above, the surge volume (
For those equipped with a piston (P ), the operation of the piston (P) becomes unstable, and the piston (P)
This unstable operation causes problems such as vibration and noise, as well as a decline in performance.

An object of the present invention is to provide a cryogenic expander that can perform stable piston operation during steady operation after completion of cool-down, can prevent the generation of vibration and noise, and can prevent a decrease in capacity.

(Means for Solving the Problems) Therefore, in the present invention, in order to achieve the above object, a piston (3) is installed inside a cylinder (2) equipped with a heat station (1), and a piston (3) is installed inside the cylinder (2). A high-pressure gas pipe (6) and a low-pressure gas pipe (7) are connected via a switching valve device (5) to an inlet/discharge passage (4) that communicates with the cylinder (2), where high pressure and low pressure are switched. A surge regulator (9) with an intermediate pressure inside is connected to the opposite side of the action chamber (8) of the piston (3), and the piston (3) is driven by a differential pressure. In the machine, a first valve means (11a) is provided between the low pressure gas pipe (7) and the surge regulator (9).
While connecting the connecting path (11), the high pressure gas pipe (6
) and the surge regulator (9), the second valve means (12
A second connection path (12) with a) was connected.

(Function) When introducing high pressure gas into the cylinder (2), the first valve means (1
1a), the surge volume (8) is set to the first
It is connected to a low pressure gas pipe (7) via a connecting path (11). As a result, the intermediate pressure value of the surge volume (8) can be lowered, and a large pressure difference between the high-pressure action chamber (8) can be secured, and the piston (3) can be operated with a large driving force. I can do it.

Furthermore, when the low pressure gas is exhausted from the cylinder (2), the surge volume (9) can be adjusted by opening the second valve means (12a).
) is connected to the high pressure gas pipe (6) via a second connection path (12). As a result, the intermediate pressure value of the surge volume (9) can be increased, and a large pressure difference between the low pressure working chamber (8) can be secured, and the piston (3) can be operated with a large driving force. I can do it.

(Example) The cryogenic expander shown in FIG. 1 has a slack piston (31) and a displacer ( A piston (3) consisting of a piston (32) and a piston ring (30...) is freely slidably housed inside the piston ring (30...). The displacer (32) is equipped with a regenerator (33) made of copper, lead, etc., has an interlocking pin (34) at the top that engages with the slack piston (31), and has an expansion space (20) at the bottom end. I am making it happen.

A high pressure gas pipe (6) and a switching valve device (5) consisting of a high pressure on-off valve (51) and a low pressure on-off valve (52) are connected to the inlet/outlet passage (4) leading to the inside of the cylinder (2). Connect the low pressure gas pipe (7) to the compressor unit (for helium, etc.)
60) so that high pressure gas can be introduced and low pressure gas can be exhausted.

In addition, a capillary (91) is used to connect the injection and discharge passage (4) to a counter chamber (10) opposite to the action chamber (8) of the slack piston (31) in the cylinder (2) where high pressure and low pressure are switched. ) is connected to the surge volume (9), which has an intermediate pressure inside, and the orifice (92).
are connected via.

With the above configuration, a first valve means (11a) consisting of a solenoid valve is provided between the low pressure gas pipe (7) and the surge regulator (9).
and a second connecting path having a second valve means (12a), which is also a solenoid valve, between the high pressure gas pipe (6) and the surge regulator (9). Connect (Step 2).

and the first and second valve means (11a) (12a)
A valve controller (13) is provided, which also controls the opening and closing of the high pressure and low pressure opening and closing valves (51) and (52) constituting the switching valve device (5).
) is inputted to the temperature detector (14) attached to the heat station (1), etc., and during the cool-down, both the first and second valve means (11a) and (12a) are closed to close the high-pressure and low-pressure on-off valves. (51) The opening/closing control of only (52) is repeated, and during steady operation after the completion of cooldown or a low temperature state close to this is detected by the temperature detector (14), high pressure opening/closing is performed as shown in Figure 2. The first valve means (11a) is opened in synchronization with the opening operation of the valve (51), and the second valve means (12a) is opened in synchronization with the opening operation of the low pressure on-off valve (52).
) open.

As a result, during steady operation after cool-down, when the high-pressure on-off valve (51) is opened to introduce high-pressure gas into the cylinder (2) and the piston (3) is raised, the first valve means (
11a), the surge volume (9) is connected to the low pressure gas pipe (7) via the first connection path (11), so that the intermediate pressure value of the surge volume (9) can be reduced.
A large pressure difference between the opposing chamber (10) and the high-pressure action chamber (8) can be secured, and the slack piston (31)
Also, the displacer (32) can be raised with a large driving force, and its operation can be stabilized.

On the other hand, when opening the low pressure on-off valve (S2) to lower the piston (3) and exhaust the expanded low pressure gas from inside the cylinder (2), the surge volume ( 9) is connected to the high pressure gas pipe (6) via the second connection path (12), the intermediate pressure value of the surge volume (9) can be increased, and the counter chamber (10) and the low pressure action chamber ( 8), it is possible to secure a large differential pressure between the slack piston (31) and the displacer (3).
2) can be lowered with a large driving force, and in this case also the operation can be stabilized.

Therefore, even during steady operation when the differential pressure between high pressure and low pressure is small, the piston (3) can be operated stably both during its ascent and descent, and it is possible to prevent the generation of vibration and noise. This can prevent a decline in performance.

In the above embodiment, the first and second valve means (11a
) (12a), high pressure and low pressure on/off valves (51) (52)
Although they are opened and closed in synchronization with each other, they may be opened and closed with a slight time difference.

Further, in the above embodiment, the first and second valve means (11a)
Although the opening and closing of (12a) was controlled by the valve controller (13) which also serves to open and close the high pressure and low pressure on/off valves (51) and (52) in the switching valve device (5), it may be controlled by an independent controller. Furthermore, the switching valve device (5) may be composed of two on-off valves (51) and (52), or may use one three-way valve, or may not be a solenoid valve, but may be used in this type of cryogenic expander. A switching mechanism using a valve motor, which has been widely used in the past, may also be used.

Furthermore, in the above embodiment, a pressure reducing means such as an orifice may be interposed between the first connecting path (11) and the second connecting path (12), and the first and second valve means ( 11a) (12
A) may be configured with a flow control valve.

Further, in the embodiment, a two-piston type with a slack piston (31) and a displacer (32) is shown, but a one-piston type without a slack piston may be used, or a single-stage displacer ( 32), but it is of course possible to use a two-stage type as shown in FIG. 3 or one having more stages.

(Effects of the invention) As described above, the low pressure gas pipe (7) and the surge regulator (9)
) having a first valve means (11a) between the first connecting passage (
11) and a second connection path (12) having a second valve means (12a) was connected between the high pressure gas pipe (6) and the surge volume (9). By opening the first valve means (11a) when introducing high pressure gas and opening the second valve means (12a) when exhausting low pressure gas from the cylinder (2), the differential pressure between the high pressure and the low pressure is small. Even during steady operation, the piston (3) can operate stably, preventing vibrations, noise, and performance degradation.

[Brief explanation of the drawing]

FIG. 1 is an overall view showing the cross-sectional structure and piping structure of the cryogenic expander of the present invention, FIG. 2 is a view showing the opening/closing timing of the valve means, and FIG. 3 is a cross-sectional view of a conventional example. ...Heat stain...Cylinder...Piston...Injection/discharge passage...Switching valve device...High pressure gas pipe...Low pressure gas pipe (8)... Action chamber (9)...Surge volume (11)...First connection path (12)...Second connection path (11a)...First valve means (12a)...・Second valve means Fig. 1 Fig. 2 Fig. 8

Claims (1)

[Claims] (1) Cylinder (2) equipped with heat station (1)
) is equipped with a piston (3), and a high-pressure gas pipe (6) and a low-pressure gas pipe (7) are connected to the inlet/discharge passage (4) leading to the inside of the cylinder (2) via a switching valve device (5). and the cylinder (2) where high pressure and low pressure are switched.
), a surge regulator (9) with an intermediate pressure inside is connected to the opposite side of the action chamber (8) of the piston (3), so that the piston (3) is driven by a differential pressure. In the low-temperature expander, the low pressure gas pipe (7)
and the surge regulator (9), the first valve means (11a
) with a first connection path (11), and a second connection path (11) with a
A cryogenic expander characterized in that a second connection path (12) is connected with a valve means (12a).