JP2002221376A - Refrigerating cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating cycle, in which refrigerant having a low critical point such as carbon dioxide is used, and a rapid pressure rise at the time of starting the cycle is relaxed for a safe cyclic operation, and secure the capacity in a stationary operation. SOLUTION: Relief equipment 11 comprises a valve element 35, a high- pressure sensitive element (bellows 37) and a vale-opening pressure regulator (an urging force regulation member 31). The equipment 11 relieves the refrigerant from a high-pressure line to a low pressure line in accordance with a refrigerant pressure of the high-pressure line. The valve element 35 changes the communication condition between the high-pressure line and the low-pressure line. The high-pressure sensitive element controls the movement of the valve element 35 in response to a refrigerant pressure in the high-pressure line. The valve-opening pressure regulator reduces the valve-opening pressure of the valve element 35 consequent upon the pressure increase in the low-pressure line. By changing the valve-opening pressure of the relief device 11 by the pressure of the low-pressure line, the valve-opening pressure of the relief device 11 can be set small, when the refrigerating cycle is stopped, and the pressure of the device 11 can be set large in a stationary operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

THE INVENTION Field of the Invention The present invention, carbon dioxide (CO ₂₎ or the like is used as the refrigerant, relates to a refrigeration cycle which can be a state in which the pressure of the high pressure line exceeds a critical pressure of the refrigerant.

[0002]

2. Description of the Related Art In a refrigeration cycle using carbon dioxide as a refrigerant, when the cycle is stopped, the pressure in a high pressure line and the pressure in a low pressure line gradually approach each other, and an equilibrium pressure of 8 to 10 is reached.
When the cycle is started from this state, the pressure in the high-pressure line suddenly abnormally rises due to a time lag between the discharge start timing of the compressor and the operation timing of the expansion device, and the inconvenience reaches 15 MPa or more. There is. Therefore, in order to cope with such an abnormal rise in the pressure, it has been considered to provide a relief valve as disclosed in Japanese Patent Application Laid-Open No. H11-248272. This is because, in a refrigeration cycle having a compressor, a radiator, a pressure control valve (expansion valve), and an evaporator, the refrigerant on the radiator outlet side (high pressure line) bypasses the pressure control valve and is evaporated on the evaporator side (low pressure line). And a relief valve that opens when the refrigerant pressure in the high-pressure line becomes equal to or higher than a predetermined pressure is provided in the bypass passage.

In addition, the publication discloses a configuration in which the relief valve is opened when the pressure on the radiator outlet side becomes equal to or higher than a predetermined pressure, a configuration in which the relief valve is opened and closed by temperature instead of the pressure, and a configuration in which the radiator outlet side is provided. A configuration in which the relief valve is opened when the pressure difference between the evaporator and the evaporator inlet side is equal to or greater than a predetermined value, and a configuration in which the relief valve is opened and closed based on the pressure difference between the pressure at the radiator outlet side and the atmospheric pressure, etc. It has been disclosed.

[0004]

However, in any of the above-described configurations, a predetermined pressure,
Since the relief valve is opened and closed by a predetermined temperature or a predetermined pressure difference, if the valve opening set value is set low in order to suppress abnormal pressure rise at the time of cycle start, during steady operation, Also, since the cycle must be operated with the valve opening set value lowered, the pressure difference between the high pressure line and the low pressure line cannot be increased during steady operation, and the predetermined cooling capacity cannot be obtained. This will affect the performance of the refrigeration cycle. Conversely, if the valve opening set value is set high with emphasis on the capacity of the refrigeration cycle, the abnormal pressure rise at the start of the cycle cannot be suppressed, and the components of the cycle may be damaged. is there.

Therefore, in the present invention, in a refrigeration cycle using a refrigerant having a low critical point such as carbon dioxide (CO ₂ ), emphasis is placed on the valve opening pressure of the relief device required at the start of the cycle and the capacity of the refrigeration cycle. Since the required valve opening pressure of the relief device is different from the required pressure, the valve opening pressure of the relief device can be varied, and the sudden pressure increase at the start of the cycle can be mitigated to operate the cycle safely. It is another object of the present invention to provide a refrigeration cycle capable of ensuring a capacity during a steady operation of the cycle.

[0006]

In order to achieve the above object, a refrigeration cycle according to the present invention comprises: a compressor for compressing a refrigerant to set a high pressure line in a supercritical state depending on operating conditions;
A radiator that cools the refrigerant compressed by the compressor; an expansion device that decompresses the refrigerant cooled by the radiator; an evaporator that evaporates the refrigerant depressurized by the expansion device; and a refrigerant in the high-pressure line. At least a relief device for relieving the refrigerant from the high-pressure line to the low-pressure line according to pressure, wherein the relief device changes a communication state between the high-pressure line and the low-pressure line, and the high-pressure line A high-pressure pressure-sensitive element that controls the movement of the valve element in response to the refrigerant pressure, and valve-opening pressure adjusting means that reduces the valve-opening pressure of the valve element with an increase in the pressure of the low-pressure line. It is characterized by comprising (claim 1).

Therefore, when the refrigeration cycle is stopped and the pressure in the low-pressure line rises (when the pressure in the high-pressure line and the pressure in the low-pressure line are close to each other), the relief device is controlled by the valve opening pressure adjusting means. , The high pressure refrigerant can be relieved to the low pressure line at the initial stage when the pressure of the high pressure line rises. When the cycle starts and the pressure in the low-pressure line becomes lower than the pressure when the cycle is stopped, the valve opening pressure of the relief device is changed to a large value by the valve opening pressure adjusting means. Can maintain a large pressure difference between the high pressure line and the low pressure line. In other words, since the valve opening pressure of the relief device can be varied by the pressure of the low pressure line, it is possible to avoid a sudden abnormal increase in pressure at the time of startup, and to secure the required performance during steady operation. It becomes possible.

Here, the valve opening pressure adjusting means expands and contracts in response to the refrigerant pressure in the low pressure line, and applies a pressure to the high pressure sensing element in the opening direction in response to the increase in the pressure in the low pressure line. Even if it is configured to have a low pressure sensing element for increasing the force (claim 2), a support for supporting the high pressure sensing element is provided so as to be displaceable in the moving direction of the valve body. A pressure receiving surface for receiving the pressure of the low pressure line may be provided on the side opposite to the support side of the high pressure sensing element.

In particular, even if the low pressure sensing element constituting the former valve opening pressure adjusting means is constituted by a bellows which can expand and contract in the direction of expansion and contraction of the high pressure sensing element in accordance with the refrigerant pressure of the low pressure line, It may be constituted by a diaphragm that can expand and contract in the expansion and contraction direction of the high-pressure sensing element according to the refrigerant pressure in the line.

In the above arrangement, means for reducing the valve opening pressure of the valve element is added as the pressure in the low pressure line increases. However, the same valve opening pressure can be obtained without adding any special means. A configuration having characteristics may be adopted. That is, a compressor that compresses the refrigerant to increase the pressure of the high-pressure line above the critical pressure of the refrigerant according to operating conditions, a radiator that cools the refrigerant compressed by the compressor, and a refrigerant that is cooled by the radiator And an evaporator that evaporates the refrigerant decompressed by the expansion device, and a relief device that relieves the refrigerant from the high-pressure line to the low-pressure line according to the refrigerant pressure of the high-pressure line. In the refrigeration cycle to be performed, the relief device,
A through hole that communicates between the high pressure line side and the low pressure line side, a valve body that changes an opening degree of the through hole, and a high pressure sensor that controls movement of the valve body in response to a refrigerant pressure in the high pressure line. Pressure element, and the ratio between the cross-sectional area of the through hole and the effective area of the portion to which the valve element is attached and receives a force from the high-pressure sensing element is increased with an increase in the pressure of the low-pressure line. The valve opening pressure of the valve body may be set to be small (claim 6).

Therefore, in such a configuration,
By adjusting the ratio of the area of the through hole whose degree of opening is adjusted by the valve element to the effective area of the portion where the valve element is attached and receives the force from the high pressure sensing element, the valve element itself receives from the low pressure side. Since the valve opening pressure can be changed according to the power, if the refrigeration cycle stops and the pressure in the low pressure line rises (when the pressure in the high pressure line and the pressure in the low pressure line are close), Thus, the high pressure refrigerant can be relieved to the low pressure line at the initial stage when the valve opening pressure decreases and the pressure in the high pressure line rises. Also, when the cycle starts and the pressure in the low pressure line falls below the pressure when the cycle is stopped, the valve opening pressure is changed to a large value. Can be kept large. In other words, since the valve opening pressure of the relief device can be varied by the pressure of the low pressure line, it is possible to avoid a sudden abnormal increase in pressure at the time of startup, and to secure the required performance during steady operation. It becomes possible.

In the above structure, the expansion device and the relief device may be formed separately or may be integrated (claims 7 and 8). May be constituted by bellows (claim 9).

A refrigeration cycle having such a relief device is suitable for a vapor compression refrigeration cycle in which the pressure of a high-pressure line can exceed the critical pressure of a refrigerant, for example, a refrigeration cycle using carbon dioxide as a refrigerant. (Claim 10).

[0014]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a refrigeration cycle 1
Is a compressor 2 for compressing the refrigerant, a radiator 3 for cooling the refrigerant, an internal heat exchanger 4 for exchanging heat between the high-pressure line and the low-pressure line, an expansion device 5 for depressurizing the refrigerant, and evaporating the refrigerant. The apparatus has an accumulator 7 for separating the refrigerant flowing out of the evaporator 6 into gas and liquid. In this cycle, the discharge side (D) of the compressor 2 is connected to the high-pressure passage 4a of the internal heat exchanger 4 via the radiator 3, and the outflow side of the high-pressure passage 4a is connected to the expansion device 5. The path from the discharge side of the compressor 2 to the expansion device 5 is a high-pressure line 8. Further, the outflow side of the expansion device 5 is connected to the low pressure passage 4b of the internal heat exchanger 4 via the evaporator 6 and the accumulator 7, and the outflow side of the low pressure passage 4b is connected to the suction side (S) of the compressor 2. By doing so, the path from the outflow side of the expansion device 5 to the compressor 2 is a low-pressure line 9. Further, in this cycle, the refrigerant in the high pressure line 8 is provided in parallel with the expansion device 5, and bypasses the expansion device 5 to relieve the refrigerant in the high pressure line 8 to the low pressure line 9 when the refrigerant pressure in the high pressure line 8 rises abnormally. A relief device 11 is provided.

As the refrigerant, a refrigerant having a low critical point, for example, carbon dioxide (CO ₂ ) is used.
The refrigerant compressed in the radiator 3 enters the radiator 3 as a high-temperature and high-pressure refrigerant, radiates and cools the refrigerant therein, and further cools the internal heat exchanger 4.
Is cooled by heat exchange with the low-temperature refrigerant flowing out of the evaporator 6 and sent to the expansion device 5 without being liquefied. The refrigerant that has reached the expansion device 5 is decompressed into low-temperature and low-pressure wet steam, exchanges heat with the air passing therethrough in the evaporator 6 to become gaseous, and then becomes high-pressure in the internal heat exchanger 4. After heat exchange with the high-temperature refrigerant in the line 8, the refrigerant is returned to the compressor 2. When the refrigerant pressure in the high-pressure line 8 rises abnormally, the relief device 11 operates to guide the refrigerant in the high-pressure line 8 to the low-pressure line 9 bypassing the expansion device 5.

FIG. 2 shows a specific configuration example of the expansion device 5 and the relief device 11. In this example, the expansion device 5 and the relief device 11 are formed separately from each other. 5 is a housing member 15
A high-pressure space 16 and a low-pressure space 17 are provided in a housing 15 constructed by assembling a and 15b, and a pressure-reducing control valve 18 is arranged in the high-pressure space 15. In this example, the low-pressure space 17 is formed in one housing member 15b, and the high-pressure space 16 is formed by assembling one housing member 15b with the other housing member 15a. Is the through hole 2 of the partition wall 19 provided in the one housing member 15b.
It is communicated through 0.

The pressure reducing control valve 1 disposed in the high pressure space 16
Reference numeral 8 denotes a valve body 23 which is seated on a valve seat 22 formed at a peripheral portion of the through hole 20, a bellows 25 which is joined to the valve body 23 via a rod 24 and is fixed to the top of the housing member 15a. The lift amount of the valve body 23 (the high-pressure space 16 and the low-pressure space 1) is changed according to the refrigerant environment (refrigerant pressure, refrigerant temperature) in the high-pressure space.
7) is adjusted.

On the other hand, the relief device 11 includes a high-pressure space 27 and a high-pressure space 2 in a housing 26 formed by assembling housing members 26a, 26b, and 26c.
7, a first low-pressure space 28 formed on one side and a second low-pressure space 29 formed on the other side of the high-pressure space 27, and a pressure control valve 30 is disposed in the high-pressure space 27. An urging force adjusting member 31 is disposed in the second low-pressure space 29. In this example, the first low-pressure space 28 is formed in the housing member 26a, the high-pressure space 27 is formed by attaching the housing member 26a to the housing member 26b, and the second low-pressure space 29 is formed in the housing member 26b. The high pressure space 27 and the first low pressure space 28 are formed by assembling the housing member 26c at the bottom, and the partition wall 32 provided in the housing member 26a is provided.
The high pressure space 27 and the second low pressure space 29 communicate with each other through the through hole 33 of the housing member 2 without communication.
6b are separated by the bottom.

The pressure control valve 3 disposed in the high-pressure space 27
Numeral 0 designates a valve body 35 seated on a valve seat 34 formed at the peripheral edge of the through hole 33, and a bellows 37 joined to the valve body 35 via a rod 36 and fixed to the bottom of the housing member 26b. When the refrigerant pressure in the high-pressure space 27 becomes equal to or higher than a predetermined valve opening pressure of the bellows itself, the valve body 35 is lifted to cause the high-pressure refrigerant to flow from the high-pressure space 27 to the first low-pressure space. The space 28 is relieved.

An urging force adjusting member 31 disposed in the second low-pressure space 29 is fixed to the bottom of the housing member 26c, and a working medium is sealed therein to increase the pressure in the second low-pressure space 29. The bellows 38 contracts in the direction of expansion and contraction of the bellows 37 (expands in the direction of expansion and contraction of the bellows 37 with a decrease in pressure), and is fixed to the free end of the bellows 38 and is connected to the high-pressure space via the bottom of the housing member 26b. And an urging rod 39 to be inserted into the arm 27. The urging rod 39 comes into contact with the bellows 37 of the high-pressure space 27 from the valve body 35 side, and the bellows 37
, That is, a biasing force in a direction of reducing the valve opening pressure of the valve body 35 (a valve opening direction).

The high-pressure space 16 of the expansion device 5 is connected to the high-pressure passage 4a of the internal heat exchanger 4 via a pipe 40 connected to the housing 15, and
The first low-pressure space 28 and the second low-pressure space 29 are connected to the evaporator 6 via a pipe 41. The high-pressure space 16 of the expansion device 5 and the high-pressure space 2 of the relief device 11
7 is communicated by a communication passage 42, and the low-pressure space 17 of the expansion device 5 and the second low-pressure space 29 of the relief device 11 are communicated by a communication passage 43.

Therefore, in the above configuration, when the pressure (low pressure) of the low pressure line 9 rises, the bellows 38 disposed in the second low pressure space 29 of the relief device 11.
The urging force for contracting the bellows 37 disposed in the high-pressure space 27, that is, the urging force in the opening direction of the valve body 35, increases with the rise of the low-pressure pressure, The valve opening pressure becomes smaller. In contrast,
When the pressure in the low pressure line 9 decreases, the relief device 1
The bellows 38 arranged in the first second low-pressure space 29 expands with a decrease in the low-pressure pressure, and an urging force for contracting the bellows 37 arranged in the high-pressure space 27, that is, of the valve body 35. The urging force in the opening direction decreases, and the relief device 1
The valve opening pressure of 1 increases up to the inherent valve opening pressure inherent in the bellows 37.

Therefore, the valve opening pressure of the relief device 11 can be changed by the bellows 38 which expands and contracts according to the low pressure, so that the valve opening pressure of the relief device 11 at the time of starting the cycle or at the time of steady operation of the cycle can be appropriately adjusted. Can be set. That is, by appropriately adjusting the type and amount of the working medium sealed in each of the bellows 37, 38, the pressure at the outlet side of the expansion device 5 (expansion device outlet pressure) Py rises and the cycle stops at P2. The relationship between the required valve opening pressure Pb of the relief device 11 and the valve opening pressure Pa of the relief device 11 required at the time of steady operation in which the expansion device outlet pressure Py decreases to P1 is shown in FIG. As shown in the figure, since the pressure can be changed substantially linearly, at the time of a cycle start in which the low pressure is increased, the high pressure line is set at an early stage when the valve opening pressure Px of the relief device 11 is reduced to increase the high pressure. The refrigerant is released from the low pressure line 8 to the low pressure line 9, so that a rapid increase in high pressure at the time of starting the cycle can be mitigated, and the cycle can be started safely.

Further, shortly after the operation of the cycle, the pressure difference between the high pressure line 8 and the low pressure line 9 increases, and the low pressure decreases. Therefore, the valve opening pressure Px of the relief device 11 increases, and the cycle operation starts. Unnecessary relief can be avoided, and the pressure difference between the high-pressure line 8 and the low-pressure line 9 can be kept large and the sufficient capacity of the refrigeration cycle 1 can be ensured during the steady operation of the cycle. Become.

In the above configuration, the expansion device 5
And the relief device 11 are configured separately from each other,
You may make it integrate as shown in FIG. That is, a high-pressure space 16 and a low-pressure space 17 constituting the expansion device 5 are provided in the housing block 45, and a high-pressure space 27 and first and second low-pressure spaces 28 and 29 constituting the relief device 11 are provided. High pressure space 16 of expansion device 5
The pressure reducing valve 18 is arranged in the inside, the pressure regulating valve 30 is arranged in the high pressure space 27 of the relief device 11, and the high pressure space 16 of the expansion device 5 is connected to the piping 40 connected to the housing block 45.
To the high pressure passage 4 a of the internal heat exchanger 4, and connects the first low pressure space 28 and the second low pressure space 29 of the relief device 11 to the passage 4 formed in the housing block 45.
The high pressure space 16 of the expansion device 5 and the high pressure space 27 of the relief device 11 are connected to a communication passage 47 formed in the housing block 45 by connecting the high pressure space 16 of the expansion device 5 and the high pressure space 27 of the relief device 11 via a pipe 41 connected to the housing block 45. Communicated by
The low-pressure space 17 of the expansion device 5 and the second low-pressure space 29 of the relief device 11 may be communicated by a communication passage 48 formed in the housing block 45. Since the other configuration is the same as the configuration shown in FIG. 2, the same portions are denoted by the same reference numerals and description thereof will be omitted.

FIG. 5 shows a modified example of the relief device 11 described above. In this modified example, the urging force adjusting member 31 disposed in the second low-pressure space 29 of the relief device 11 includes a housing member 26c. The diaphragm is fixed to the bottom portion, and the working medium is sealed therein, and contracts in the direction of expansion and contraction of the bellows 37 as the pressure in the second low-pressure space increases (extends in the direction of expansion and contraction of the bellows 37 as the pressure decreases). 50, and a biasing rod 39 fixed to the free end of the diaphragm 50 and inserted into the high-pressure space 27 through the bottom of the housing member 26b. The other configuration is the same as the configuration shown in FIG.

Therefore, even in such a configuration,
When the pressure (low pressure) of the low pressure line 9 rises, the diaphragm 50 arranged in the second low pressure space 29 of the relief device 11 contracts with the rise of the low pressure pressure, so it is arranged in the high pressure space 27. The urging force for contracting the bellows 37, that is, the urging force in the opening direction of the valve body 35 increases, and the valve opening pressure of the relief device 11 decreases.
On the other hand, when the pressure in the low-pressure line decreases, the diaphragm 50 arranged in the second low-pressure space 29 of the relief device 11 expands as the low-pressure pressure decreases, and is stored in the high-pressure space 27. The urging force for contracting the bellows 37, that is, the urging force in the opening direction of the valve body 35 is reduced, and the valve opening pressure of the relief device 11 reaches the inherent valve opening pressure inherent in the bellows 37. Until it gets bigger.

Therefore, even in such a configuration, the valve opening pressure of the relief device 11 can be changed by the diaphragm 50 which expands and contracts according to the low pressure, so that the relief device can be used at the time of starting the cycle or at the time of steady operation of the cycle. 1
The first valve opening pressure can be set appropriately. That is,
By appropriately adjusting the type and amount of the working medium sealed in the bellows 37 and the diaphragm 50, the valve opening pressure Pb of the relief device 11 required when the cycle is stopped when the expansion device outlet pressure Py increases to P2. The relationship with the valve opening pressure Pa of the relief device 11 required during the steady operation in which the expansion device outlet pressure Py decreases to P1 can be changed substantially linearly, for example, as shown in FIG. Therefore, at the start of a cycle in which the low pressure is increased, the valve opening pressure of the relief device is reduced to increase the high pressure from the high pressure line 8 to the low pressure line 9 at the initial stage.
As a result, the refrigerant can escape, and the rapid rise of the high pressure at the start of the cycle can be mitigated, so that the cycle can be started safely.

Further, a short while after the operation of the cycle, the pressure difference between the high pressure line 8 and the low pressure line 9 increases, and the low pressure decreases. Therefore, the valve opening pressure of the relief device 11 increases, and the cycle operation starts. Unnecessary relief can be avoided, and the pressure difference between the high-pressure line 8 and the low-pressure line 9 can be kept large and the sufficient capacity of the refrigeration cycle 1 can be ensured during the steady operation of the cycle. Become.

In such a configuration, the expansion device 5 and the relief device 11 may be integrated as shown in FIG. That is, a high-pressure space 16 and a low-pressure space 17 that constitute the expansion device 5 are provided in the housing block, and a high-pressure space 27 and first and second low-pressure spaces 28 and 29 that constitute the relief device 11 are provided. The pressure reducing valve 18 is disposed in the high pressure space 16 of the device 5, the pressure regulating valve 30 is disposed in the high pressure space 27 of the relief device 11, and the high pressure space 16 of the expansion device 5 is connected to a pipe 40 connected to the housing block 45. Through the high-pressure passage 4 of the internal heat exchanger 4
a, and connects the first low-pressure space 28 and the second low-pressure space 29 of the relief device 11 to the evaporator 6 via a passage 46 formed in the housing block 45 and a pipe 41 connected to the housing block 45. Also, the high-pressure space 15 of the expansion device 5 and the high-pressure space 27 of the relief device 11 communicate with each other through a communication passage 47 formed in the housing block 45. The second low-pressure space 29 may be communicated with a communication passage 48 formed in the housing block 45. Since the other configuration is the same as the configuration shown in FIG. 5, the same portions are denoted by the same reference numerals and description thereof will be omitted.

FIG. 7 shows a configuration showing another example of the relief device 11. In this configuration example, the relief device 11 is configured by supporting a bellows 56 in a housing 55 formed by assembling housing members 55a and 55b, and accommodating a movable body 57 movable in the expansion and contraction direction of the bellows 56. Have been. In this example, the housing 55 includes a housing member 55a on which the movable body 57 slides, and a housing member 55b assembled to the housing member 55a.
7. A pedestal portion 57a that is slidably attached to a cylindrical member 58 provided integrally inside the housing member 55b and supports the bellows 56, and a cylindrical member formed integrally with the pedestal portion 57a. It has a ring-shaped portion 57b that is in sliding contact with the outer peripheral surface of the housing member 58 and the inner peripheral surface of the housing member 55a.

On the inner surface of the housing member 55a, a stopper 59a with which the ring-shaped portion 57b abuts and a stopper 59b with which the pedestal portion 57a abuts are formed. The cylindrical member 58, the housing members 55a and 55b, and the ring-shaped portion 57b. An annular low-pressure space 60 is formed by the enclosed space, and a portion of the ring-shaped portion 57b facing the low-pressure space 60 forms a pressure-receiving surface 61 that receives pressure in the low-pressure space. A high-pressure space 62 is formed by a space surrounded by the movable body 57 and the housing member 55a,
In this high-pressure space 62, a bellows 56 supported by the pedestal portion 57a is fixed and stored at the top of the housing member 55a.

The inside of the cylindrical member 58 has a ring-shaped portion 57b.
The valve body 64 fixed to the pedestal portion 57a of the movable body 57 is vertically provided inside the cylindrical member 58, and communicates with the high-pressure space 62 through a communication hole 63 formed in the movable member 57. When the ring-shaped portion 57b contacts the stopper 59a, the valve body 64 is seated on a valve seat portion 65 having a valve opening formed by squeezing the inside of the tubular member 58. The movable body 57, the bellows 56, and the valve body 64 constitute a pressure control valve 66. When the movable body 57 is in contact with the stopper 59a, the refrigerant pressure in the high-pressure space 62 is reduced. When the pressure becomes equal to or higher than the predetermined valve opening pressure of the bellows 56 itself, the valve body 64 is lifted to release the high-pressure refrigerant from the high-pressure space 62 through the inside of the tubular member 58. The lift of the valve body 64 is
7a is limited to a range until it comes into contact with the stopper 59b, and the stopper 59b prevents the movable body 57 from coming off the cylindrical member 58. Since the inflation device 5 has the same configuration as the configuration shown in FIG.
The same portions are denoted by the same reference numerals and description thereof is omitted.

The high-pressure space 16 of the expansion device 5 is connected to the high-pressure passage 4 a of the internal heat exchanger 4 via a pipe 40 connected to the housing 15, and is connected to the valve seat 65 inside the tubular member 58. The downstream portion is connected to the evaporator 6 via a pipe 68. The high-pressure space 16 of the expansion device 5 and the high-pressure space 62 of the relief device 11 are communicated by a communication passage 69, and the low-pressure space 6 of the relief device 11
0 is connected to the low-pressure space 17 of the expansion device 5 via the communication passage 67, and is formed in the tubular member 58 at a position downstream of the valve seat 65 inside the tubular member 58. The connection is made through a hole 99.

Therefore, in the above configuration, when the pressure (low pressure) Py on the outlet side of the expansion device increases, the pressure applied to the pressure receiving surface 61 of the ring-shaped portion 57a increases, and the urging force in the direction of compressing the bellows 56 is applied. Increases, and the valve opening pressure Px of the valve body 64 decreases. Conversely, when the pressure at the expansion device outlet side (low pressure) Py decreases, the ring-shaped portion 57
The pressure applied to the pressure receiving surface 61a decreases, the urging force in the direction of compressing the bellows decreases, and the valve opening pressure of the valve body 64 increases. For this reason, the valve opening pressure of the relief device 11 has a characteristic that it decreases as the low pressure increases.

For example, the expansion device outlet pressure (low pressure) P
As shown in FIG. 3, the relationship between y and the valve opening pressure Px of the relief device 11 is required when the cycle is stopped when the pressure Py at the outlet of the expansion device 5 (expansion device outlet pressure) Py rises to P2. The valve opening pressure of the relief device 11 is Pb, and the valve opening pressure of the relief device 11 required during steady operation in which the expansion device outlet pressure Py decreases to P1 is Pa (Pa> P
b), and assuming that the period changes linearly as shown in FIG. 3, the relationship between the expansion valve outlet side pressure Py and the valve opening pressure Px of the relief device is expressed by Px + αPy = K (constant). Can be. Therefore, assuming that the area of the pressure receiving surface 61 facing the low pressure chamber 60 of the ring-shaped portion 57b is Sr and the effective area of the portion of the pedestal portion 57a receiving the force from the bellows 57 is Sb, the refrigerant pressure Py on the expansion device outlet side causes a low pressure. The urging force Fy received by the movable body 57 from the space 60 is Py · Sr
Assuming that the urging force received by the valve body 64 from the low pressure side is negligibly small, then approximately Py · Sr /
The valve opening pressure is reduced by the amount of Sb, and in order to obtain the above-described linear characteristic, it is necessary to design so that α = Sr / Sb.

As described above, according to this configuration, the characteristic to be obtained may be determined by the area ratio between Sr and Sb. For example, when Py in the steady cycle operation is 3 MPa, the valve opening pressure Px is increased by 14 MPa. If it is desired to obtain a characteristic in which the valve opening pressure Px is 12 MPa when Py at the cycle stop is 9 MPa, α = 1/3, K = 15 (MP
By setting Sr to be 1 / 3Sb, it becomes possible to appropriately set the valve opening pressure of the relief device at the time of starting the cycle or during the steady operation of the cycle.

Therefore, even in such a configuration, the refrigerant is transferred from the high pressure line 8 to the low pressure line 9 in the initial stage when the valve opening pressure of the relief device 11 is reduced and the high pressure starts to rise at the start of the cycle in which the low pressure increases. Can be easily escaped, so that a rapid rise in high pressure at the time of starting the cycle can be mitigated, and the cycle can be started safely. Further, a short while after the operation of the cycle, the pressure difference between the high pressure line 8 and the low pressure line 9 increases, and the low pressure decreases.
1, the valve opening pressure of the refrigeration cycle 1 can be avoided, and unnecessary relief during the cycle operation can be avoided. During the steady operation of the cycle, the pressure difference between the high pressure line 8 and the low pressure line 9 is kept large and the refrigeration cycle 1 is operated. Sufficient ability can be secured.

In the configuration shown in FIG. 7 described above, an example is shown in which the expansion device 5 and the relief device 11 are configured separately, but they may be integrated as shown in FIG. That is, while providing the high-pressure space 16 and the low-pressure space 17 constituting the expansion device 5 in the housing block 70,
High-pressure space 62 and low-pressure space 6 constituting relief device 11
0 and the cylindrical member 5 provided in the housing block 70.
8 and a movable body 57 attached to the cylindrical member 58, a pressure-reducing control valve 18 is arranged in the high-pressure space 16 of the expansion device 5, and a bellows 56 is arranged in the high-pressure space of the relief device 11. A valve body 64 that is seated on a valve seat 65 protruding from the inner wall inside the tubular member 58 and moves integrally with the movable body 57 is provided.
And the high-pressure space 62 of the relief device 11 through a communication passage 71, and the low-pressure space 17 of the expansion device 5, the low-pressure space 60 of the relief device 11, and the valve seat 6 inside the tubular member 58.
5 is connected to a portion downstream of the housing block 70 by a passage 72 formed in the housing block 70, and the high pressure space 16 of the expansion device 5 is connected to the pipe 40 connected to the housing block 70.
To the high-pressure passage 4a of the internal heat exchanger 4 via a pipe, and a portion downstream of the valve seat 65 inside the tubular member 58 is connected to the evaporator 6 via a pipe 68. Is also good. Since the other configuration is the same as the configuration shown in FIG. 7, the same portions are denoted by the same reference numerals and description thereof will be omitted.

The configuration shown in FIG. 7 described above is a configuration suitable for a case where the urging force received from the low pressure side of the valve body 64 is negligibly small. However, as the bellows 56 becomes smaller, the size becomes smaller. Therefore, the urging force received from the low pressure side of the valve body 64 cannot be ignored. Therefore, FIG.
In the configuration shown by, in order to obtain the substantially linear characteristic shown in FIG. 3, that is, the characteristic satisfying Px + αPy = K (constant), α is appropriately set as the ratio of Sr to Sb (Sr / Sb). However, if it is not possible to ignore the urging force that the valve element receives from the low pressure side, it is desirable to determine α in relation to the urging force that the valve element receives from the low pressure side It will be. Therefore, in such a case, it is preferable to use a relief device 11 as shown in FIG.

That is, the relief device 11 shown in FIG.
Has a high pressure space 76 and a low pressure space 7 in a housing 75 which is constructed by assembling housing members 75a and 75b.
7 and a pressure regulating valve 78 is arranged in the high-pressure space 76. In this example, the low-pressure space 77 is formed in one housing member 75b, and the high-pressure space 76 is formed in one housing member 75b in the other housing member 75b.
a is formed by assembling the high pressure space 7
6 and the low-pressure space 77 are communicated with each other through a through hole 80 of a partition wall 79 provided in one housing member 75b.

The pressure-reducing control valve 7 arranged in the high-pressure space 76
Reference numeral 8 denotes a valve body 83 which is seated on a valve seat 82 formed at a peripheral portion of the through hole 80, a bellows 85 which is joined to the valve body 83 via a rod 84 and is fixed to the top of the housing member 75a. The high-pressure space 7
When the pressure of the refrigerant in the tube 6 becomes equal to or higher than a predetermined valve opening pressure of the bellows itself, the valve 83 is lifted to relieve the high-pressure refrigerant from the high-pressure space 76 to the low-pressure space 77.

The sectional area S1 of the through hole 80 and the valve body 8
By appropriately setting the ratio (S1 / S2) of the portion to which the force is applied from the bellows 85 to which the component 3 is attached to (S1 / S2) as α as described above, as shown in FIG. ), A substantially linear characteristic of reducing the valve opening pressure with an increase in pressure, that is, a characteristic of Px + αPy = K (constant) is obtained.

The expansion device 5 has the same configuration as that shown in FIG. 2, and the high-pressure space 16 of the expansion device 5 is connected to the high-pressure passage 4a of the internal heat exchanger 4 through a pipe 40 connected to the housing 15. And the low-pressure space 77 of the relief device 11 is connected to the evaporator 6 via a pipe 68. Further, the high-pressure space 16 of the expansion device 5 and the relief device 1
The first high-pressure space 76 is connected via a pipe 69, and the low-pressure space 17 of the expansion device 5 and the low-pressure space 77 of the relief device 11 are connected via a pipe 87.

Therefore, in the above-described configuration, when the pressure (low pressure) Py on the outlet side of the expansion device becomes high, the valve element 83
The pressure applied to itself increases, the urging force in the direction of compressing the bellows 85 increases, and the valve opening pressure Px of the valve element 83 increases.
Becomes smaller. Conversely, the pressure at the outlet of the expansion device (low pressure)
When Py decreases, the pressure applied to the valve element 83 itself decreases, the urging force in the direction of compressing the bellows 85 decreases, and the valve opening pressure of the valve element 83 increases. For this reason, the valve opening pressure of the relief device 11 has a characteristic that it decreases as the low pressure increases.

Therefore, even in such a configuration, the valve opening pressure of the relief device 11 is reduced at the start of the cycle in which the low pressure is increased, and the refrigerant flows from the high pressure line 8 to the low pressure line 9 in the initial stage when the high pressure starts to increase. Can be easily escaped, so that a rapid rise in high pressure at the time of starting the cycle can be mitigated, and the cycle can be started safely. Further, a short while after the operation of the cycle, the pressure difference between the high pressure line 8 and the low pressure line 9 increases, and the low pressure decreases.
1, the valve opening pressure of the refrigeration cycle 1 can be avoided, and unnecessary relief during the cycle operation can be avoided. During the steady operation of the cycle, the pressure difference between the high pressure line 8 and the low pressure line 9 is kept large and the refrigeration cycle 1 is operated. Sufficient ability can be secured. Further, according to such a configuration, it is not necessary to provide a special mechanism for varying the valve opening pressure of the relief device 11, and it is possible to avoid a complicated structure.

In the above-described configuration, an example in which the inflation device 5 and the relief device 11 are separately provided has been described.
0 may be integrated. That is, the high-pressure space 16 and the low-pressure space 17 that constitute the expansion device 5 are provided in the housing block 90, and the high-pressure space 76 and the low-pressure space 77 that constitute the relief device 11 are provided. , A pressure control valve 78 is disposed in the high-pressure space 76 of the relief device 11, and the high-pressure space 16 of the expansion device 5 is connected to the internal heat exchanger via a pipe 40 connected to the housing block 90. 4 and the low-pressure space 77 of the relief device 11 is connected to the passage 9 formed in the housing block 90.
2 and a piping 68 connected to the housing block 90, and connected to the evaporator 6. The high-pressure space 16 of the expansion device 5 and the high-pressure space 76 of the relief device 11 are connected to a communication passage 93 formed in the housing block 90. Communicated by
The low-pressure space 17 of the expansion device 5 and the low-pressure space 77 of the relief device 11 may be communicated by a communication passage 94 formed in the housing block 90. The other configuration is the same as the configuration shown in FIG. 9, and thus the same portions are denoted by the same reference numerals and description thereof will be omitted.

In each of the above embodiments, a bellows type pressure control valve is used as the relief device 11, but a diaphragm type pressure control valve may be used. In each configuration example, the relief device 1
1 shows a case where the pressure from the outlet side of the expansion device is directly introduced into the low pressure chambers 29, 60 and 77.
The low-pressure pressure may be introduced from any location of the above.

[0049]

As described above, according to the present invention,
The pressure relief device of the vapor compression refrigeration cycle, in which the pressure of the high pressure line can exceed the critical pressure of the refrigerant, reacts to the valve body that changes the communication between the high pressure line and the low pressure line, and the refrigerant pressure of the high pressure line. A high-pressure pressure-sensitive element for controlling the movement of the valve body, and a valve-opening pressure adjusting means for reducing the valve-opening pressure of the valve body with an increase in the pressure of the low-pressure line, or By adjusting the ratio of the area of the through hole whose opening is adjusted by the valve element and the effective area of the part where the valve element is attached and receives the force from the high pressure sensing element, the valve is increased with the increase of the pressure in the low pressure line. Since the valve opening pressure of the body is reduced, when the refrigeration cycle is stopped and the pressure in the low pressure line rises (when the pressure in the high pressure line and the pressure in the low pressure line are close to each other), the relief device is opened. Reducing valve pressure It can be, it is possible to operate safely cycle to alleviate sudden pressure increase at the time of the cycle start.

When the cycle starts and the pressure in the low pressure line decreases, the valve opening pressure of the relief device can be changed to a large value. Therefore, the pressure difference between the high pressure line and the low pressure line should be kept large. The cooling capacity can be secured during the steady operation of the cycle.

As a specific mode of the valve opening pressure adjusting means,
It has a low-pressure sensing element such as a bellows or diaphragm that expands and contracts in response to the refrigerant pressure in the low-pressure line and increases the urging force in the valve opening direction to urge the high-pressure sensing element as the pressure in the low-pressure line increases. Even if it is configured to be configured, a support that supports the high pressure sensing element is provided so as to be displaceable in the moving direction of the valve body,
A pressure-receiving surface for receiving the pressure of the low-pressure line may be provided on the opposite side of the support from the support side of the high-pressure pressure-sensitive element. With such a configuration, the high-pressure pressure-sensitive element itself may be provided. It is possible to easily change the inherent valve opening pressure by changing the urging force for urging the high pressure sensing element.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a refrigeration cycle according to the present invention.

FIG. 2 is a sectional view showing a specific configuration example of an expansion device and a relief device of the refrigeration cycle according to FIG. 1;

FIG. 3 is a diagram showing an example of a valve opening pressure characteristic of a relief device with respect to an expansion device outlet pressure Py.

FIG. 4 is a cross-sectional view showing a configuration example in which the expansion device and the relief device shown in FIG. 2 are integrated.

FIG. 5 is a sectional view showing a configuration example in which a relief device is modified from the configuration shown in FIG. 2;

FIG. 6 is a cross-sectional view showing a configuration example in which the expansion device and the relief device shown in FIG. 5 are integrated.

FIG. 7 is a cross-sectional view showing an example in which the relief device is replaced with another configuration in the configuration shown in FIG. 2;

FIG. 8 is a cross-sectional view showing a configuration example in which the expansion device and the relief device shown in FIG. 7 are integrated.

FIG. 9 is a cross-sectional view showing an example in which the relief device is replaced with another configuration in the configuration shown in FIG. 2;

FIG. 10 is a cross-sectional view illustrating a configuration example in which the expansion device and the relief device illustrated in FIG. 9 are integrated.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Compressor 3 Radiator 5 Expansion device 6 Evaporator 8 Low pressure line 9 High pressure line 11 Relief device 35, 64, 83 Valve element 37, 38, 56, 85 Bellows 50 Diaphragm 57 Moving body 57b Pressure receiving surface 80 Through hole

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) F25B 1/00 395 F25B 1/00 395Z 41/04 41/04 HF term (reference) 3H056 AA02 BB24 BB45 BB50 CA07 CA19 CB02 CD06 DD04 EE06 GG08 GG13 3H059 AA06 BB01 BB35 CD03 CE06 DD01 DD17 EE01 FF08 FF12 FF15

Claims (10)

[Claims] 1. A compressor for compressing a refrigerant to increase the pressure of a high pressure line above a critical pressure of the refrigerant depending on operating conditions;
A radiator that cools the refrigerant compressed by the compressor; an expansion device that decompresses the refrigerant cooled by the radiator; an evaporator that evaporates the refrigerant depressurized by the expansion device; and a refrigerant in the high-pressure line. In a refrigeration cycle configured to include at least a relief device for relieving the refrigerant from the high-pressure line to the low-pressure line according to pressure, the relief device changes a communication state between the high-pressure line and the low-pressure line. A valve element, a high-pressure sensing element that controls the movement of the valve element in response to a refrigerant pressure in the high-pressure line, and a valve-opening pressure that decreases the valve-opening pressure of the valve element with an increase in the pressure in the low-pressure line. A refrigeration cycle comprising an adjusting means. 2. The valve opening pressure adjusting means expands and contracts in response to a refrigerant pressure in the low pressure line, and urges the high pressure sensing element with an increase in the pressure in the low pressure line in an opening direction of the valve element. The refrigeration cycle according to claim 1, further comprising a low-pressure pressure-sensitive element for increasing the urging force on the refrigeration cycle. 3. The refrigeration system according to claim 2, wherein said low pressure sensing element is constituted by a bellows which can expand and contract in a direction in which said high pressure sensing element expands and contracts in accordance with a refrigerant pressure of said low pressure line. cycle. 4. The refrigeration apparatus according to claim 2, wherein said low pressure sensing element is constituted by a diaphragm which can expand and contract in a direction in which said high pressure sensing element expands and contracts in accordance with a refrigerant pressure of said low pressure line. cycle. 5. The valve-opening pressure adjusting means is provided with a movable body that supports the high-pressure sensing element so as to be displaceable in a moving direction of the valve body. 2. The refrigeration cycle according to claim 1, wherein a pressure receiving surface for receiving the pressure of the low pressure line is provided on a side opposite to the refrigeration line. 6. A compressor for compressing a refrigerant to increase a pressure of a high pressure line above a critical pressure of the refrigerant depending on an operation condition;
A radiator that cools the refrigerant compressed by the compressor; an expansion device that decompresses the refrigerant cooled by the radiator; an evaporator that evaporates the refrigerant depressurized by the expansion device; and a refrigerant in the high-pressure line. A refrigeration cycle configured to include at least a relief device that relieves the refrigerant from the high-pressure line to the low-pressure line according to pressure, wherein the relief device includes a through-hole that communicates the high-pressure line side with the low-pressure line side. A valve element for changing the opening degree of the through hole; and a high pressure sensing element for controlling the movement of the valve element in response to a refrigerant pressure in the high pressure line, wherein a cross sectional area of the through hole and the valve are provided. The ratio of the effective area of a portion to which a body is attached and receives a force from the high pressure sensing element is set so as to decrease the valve opening pressure of the valve body with an increase in the pressure of the low pressure line. Refrigeration cycle characterized by. 7. The inflating device and the relief device,
The refrigeration cycle according to claim 1 or 6, which is configured separately. 8. The expansion device and the relief device,
The refrigeration cycle according to claim 1 or 6, wherein the refrigeration cycle is integrated. 9. The refrigeration cycle according to claim 1, wherein said high pressure sensing element is constituted by a bellows. 10. The refrigeration cycle according to claim 1, wherein the refrigerant is carbon dioxide.