JPS6160348B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called gas cycle refrigeration system that uses gas as a working substance, and in particular, the piston drive method thereof is significantly stabilized compared to conventional types, and a refrigeration system with high energy efficiency is obtained. The purpose is to

Various types of gas cycle refrigeration systems are known, but they can be roughly divided into two types: one in which the reciprocating motion of the piston of the expander is performed by a crank device, and the other in which the reciprocating movement of the piston of the expander is performed by gas pressure. There is. Mechanically reciprocating the piston using a crank device is large and expensive, and requires oil lubrication for sliding and rotating parts, making it impossible to completely prevent oil vapor from entering the working gas. This is difficult, and there is a risk that the refrigeration capacity will decrease. The method of reciprocating the piston using gas pressure is easy to downsize and can be made at low cost, but it is difficult to control the stroke of the reciprocating movement of the piston, and the piston may collide with the cylinder end wall. There is a risk that problems may occur, resulting in noise, vibration, etc., and high precision is required for each component, such as a fixed throttle valve.

According to the present invention, the expander has a first space defined by one end surface of the piston that reciprocates within the cylinder.
The other end surface of the piston is divided into two to define second and third spaces between the piston and the cylinder, and the second and third spaces contain the compressor. A gas cycle refrigeration system is provided in which conduits on the discharge side and on the suction side are each connected via a variable flow rate throttle valve.

In a preferred embodiment of the invention, the flow rate of the throttle valve is made to vary in accordance with the temperature, thereby making it possible to provide the piston with an optimum control force for the current temperature, and to provide the piston with the cylinder end. Collisions with walls can be prevented and refrigeration output can be increased.

The functions and effects of the present invention will be described below with reference to the drawings.

Figure 1 shows, for example, Patent No. 807732
18626) is a schematic diagram showing a conventional gas cycle refrigeration system. One end surface of the piston 11 defines a first variable volume space 10 within the cylinder 9, and the other end surface is divided into two to form a large diameter end surface and a small diameter end surface, and the large diameter end surface defines a first variable volume space 10 within the cylinder 9.
A second space 13 is created in the cylinder 9 by 2 and 14.
The small-diameter end face defines a third space 15 within the small-diameter cylinder connected to the cylinder 9. The spaces 13, 15 are connected to the discharge conduit 2 and the suction conduit 3 of the compressor 1 via fluid conduits 16, 17 having fixed throttle valves 18, 19, respectively.

When the piston 11 is at the lowest position in the figure, the low pressure switching valve 5 is closed and the high pressure switching valve 4 is open.
The high-pressure gas is introduced into the first space 10 through the fluid conduit 6, the regenerator 7, and the heat exchanger 8 for extracting refrigeration output. The force due to the gas pressure acting on the end face of the piston 11 facing the space 10 causes the space 1 of the piston 11 to
The piston 11 rises as the force becomes larger than the force due to the gas pressure acting on the end faces facing the pistons 3 and 15. The upward movement of the piston 11 is limited by the increase in internal pressure in the spaces 13, 15 due to the flow resistance of the fixed throttle valves 18, 19. When the piston 11 reaches near its uppermost position, the high pressure switching valve 4 closes and the low pressure switching valve 5 opens. The gas in the space 10 is sucked into the compressor 1 and has a low pressure, and a downward force is applied to the piston 11. Due to the fluid resistance of the fixed throttle valves 18, 19, the downward force of the piston 11 is weakened. The reciprocating speed of the piston 11 is determined by the fixed throttle valve 1.
The refrigeration power is taken from the heat exchanger 8, determined by the degree of fluid resistance at 8 and 19.

FIG. 2 is a schematic diagram showing a preferred embodiment of the present invention, and parts similar to those in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted. As is clear from the above description, the movement of the piston 11 is caused by the difference between the pressure in the space 10 and the pressure in the spaces 13 and 15.
The speed of movement of the piston 11 is determined by the fluid resistance of the throttle valve. In recent years, this type of refrigeration equipment is a one-stage type that can be used from room temperature to liquid hydrogen temperature (300K to 20K).
It has become necessary to perform refrigeration, and therefore the temperature of the heat exchanger 8 for extracting the refrigeration output and the space 10 needs to vary in the range of 300K to 20K. 20K
The ratio of the temperatures between the state of . The resistance of the fluid flowing through the high-pressure and low-pressure switching valves 4 and 5, the conduit 6, the regenerator 7, and the refrigeration output extraction heat exchanger 8 is significantly higher at low temperatures than at room temperature, and as a result, the The rates of pressure increase and pressure decrease are smaller at low temperatures than at room temperature. If the throttle valves 18 and 19 are kept constant, speed control becomes excessive at low temperatures, making it impossible to achieve the desired low temperature.

According to a preferred embodiment of the present invention, the throttle valves 18' and 19' are variable flow rate throttle valves controlled by temperature sensing sections 20 and 21 that sense the temperature of the space 10, as shown in FIG. The temperature sensing parts 20 and 21 are attached to the low temperature end of the cylinder 9 or the heat exchanger 8 by brazing, bolting, etc. so as to avoid thermal contact resistance.
A needle valve element 29 is provided at the tip of the valve rods 22, 23 that move in accordance with temperature changes. In FIG. 3, the temperature sensing parts 20 and 21 are made of a material with high thermal conductivity and a large coefficient of thermal expansion, such as aluminum, and the valve stems 22 and 23 are made of a material with relatively low thermal conductivity, such as stainless steel. do. Note that the needle valve body 29 is provided with a relief groove 30 to ensure a minimum flow rate, but of course this is provided with the corresponding valve seat 27.
may be provided. In addition, in FIG. 3, 25 is a passage connected between the discharge side and the suction side conductor of the compressor 1;
6 is a passage corresponding to or connected to the fluid conduits 16, 17, 28 is preferably a part of the outer wall of the cylinder 9, and 24 is a sheath for the valve stems 22, 23. By appropriately determining the length and material of the temperature sensing parts 20 and 21 and the dimensions of the needle valves 27 and 29, the variable flow rate restricting valves 18' and 19' can be adjusted appropriately in response to the temperature of the space 10 or the heat exchanger 8. The valve opening can be automatically controlled to increase in size as the temperature decreases, and the optimal refrigeration output can be obtained for the temperature from room temperature to the desired refrigeration temperature.
Since the movement of the piston can be controlled in relation to temperature, the piston does not collide with the cylinder end wall or lack a stroke.

In the above embodiment, both the valves 18' and 19' were described as ones that change the flow rate according to temperature changes, but it is also possible to use only one of the valves 18' and 19' as one that changes the flow rate according to temperature changes. , it is possible to increase energy efficiency compared to conventional devices.

In the above-described embodiment, a metal rod that expands and contracts thermally is used as the temperature-sensing section, but it may be replaced by a means for displacing the needle valve body 29 in the length direction by a change in temperature, such as a gas or liquid pressure bellows. It is also possible to make the valve opening degree externally adjustable and electrically connect this to the temperature sensing section. Note that by limiting the maximum valve opening degree, the lowest temperature that can be achieved can be limited.

The gas cycle refrigeration apparatus according to the present invention has a simple mechanism, high reliability, small size, low cost, high efficiency, and low vibration.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a conventional gas cycle refrigeration system. FIG. 2 is a schematic diagram of a refrigeration system according to the present invention. FIG. 3 is a schematic cross-sectional view of the variable flow rate restrictor. 1: Compressor, 4, 5: High pressure, low pressure switching valve, 9:
Cylinder, 11: Piston, 10: First variable volume space, 13, 15: Second and third spaces, 1
8', 19': Variable flow rate throttle valve, 20, 21: Temperature sensing section.

Claims (1)

[Scope of Claims] 1. In a gas cycle refrigeration system, an expander is defined as a first variable volume space defined by one end surface of a piston that reciprocates within a cylinder, and the other end surface of the piston is defined as a first variable volume space. is divided into two to define second and third spaces between each cylinder, and in the second and third spaces, conduits on the discharge side and suction side of the compressor are respectively connected to variable flow rate throttles. The gas cycle refrigeration system is characterized in that the flow rate of at least one of the valves is changed in response to the temperature of the first variable volume space connected through a valve. 2. The throttle valve is a throttle valve in which the opening degree of a needle valve part connected to a valve stem is provided with a temperature sensing part having high thermal conductivity and a large coefficient of thermal expansion that changes in the length direction with temperature followability. 2. The gas cycle refrigeration system according to claim 1, wherein the flow rate changes according to temperature. 3. Claim 1, characterized in that the throttle valve is a needle valve, and the flow rate is made variable by displacing the needle valve body in the longitudinal direction using means for generating displacement in response to temperature changes.
The gas cycle refrigeration device described in Section 1.