WO2002057695A1

WO2002057695A1 - Refrigerating cycle

Info

Publication number: WO2002057695A1
Application number: PCT/JP2001/010045
Authority: WO
Inventors: Hajime Mukawa
Original assignee: Zexel Valeo Climate Control Corporation
Priority date: 2001-01-22
Filing date: 2001-11-16
Publication date: 2002-07-25
Also published as: JP2002221376A

Abstract

A refrigerating cycle using a refrigerant with low critical point such as carbon dioxide, comprising a relief device (11) for relieving the refrigerant from a high pressure line to a low pressure line according to a refrigerant pressure in the high pressure line having a valve element (35) for varying the state of communication between the high pressure line and the low pressure line, a high pressure sensitive element (bellows (37)) for controlling the movement of the valve element (35) in response to the refrigerant pressure in the high pressure line, and a valve opening pressure regulating means (energizing force adjusting means (31) for reducing an opening pressure for the valve element (35) with an increase in pressure in the low pressure line, whereby the valve opening pressure of the relief valve (11) can be set lower when the refrigerating cycle is stopped and set larger in stationary operation by varying the valve opening pressure of the relief device (11) with the pressure in the low pressure line, the cycle can be operated safely by relieving an abrupt pressure rise at the start of the cycle, and the capacity of the cycle in stationery operation can be assured.

Description

frozen

Technical field

The present invention relates to a refrigeration cycle in which carbon dioxide (co ₂ ) or the like is used as a refrigerant, and a pressure in a high-pressure line can exceed a critical pressure of the refrigerant.

Akira Background technology

book

In a refrigeration cycle using carbon dioxide as a refrigerant, when the cycle is stopped, the pressure in the high-pressure line and the pressure in the low-pressure line gradually approach each other, and the equilibrium pressure may reach 8 to 10 MPa. When the cycle is started from, the pressure of the high pressure line suddenly rises abnormally due to the time lag between the compressor discharge start timing and the expansion device operation timing, and there is a problem that the pressure reaches 15 MPa or more. For this reason, in order to cope with such an abnormal rise in pressure, it has been considered to provide a relief valve as disclosed in Japanese Patent Application Laid-Open No. 11-248272. This is because, in a refrigeration cycle having a compressor, a radiator, a pressure control valve (expansion valve), and an evaporator, the refrigerant at the radiator outlet (high-pressure line) bypasses the pressure control valve and is transferred to the evaporator (low-pressure line). ) Is provided, and a relief valve that opens when the refrigerant pressure in the high-pressure line exceeds a predetermined pressure is provided in the bypass passage.

The publication also discloses a configuration in which the relief valve is opened when the pressure on the radiator outlet side is equal to or higher than a predetermined pressure, a configuration in which the relief valve is opened and closed by temperature instead of pressure, and a configuration in which the radiator outlet side is closed. A configuration in which the relief valve is opened when the pressure difference from the evaporator inlet side exceeds a predetermined value, and a configuration in which the relief valve is opened and closed based on the pressure difference between the radiator outlet side pressure and the atmospheric pressure, etc. It has been disclosed. However, in any of the above-described configurations, the relief valve is opened and closed by a predetermined pressure, temperature, or pressure difference that is set in advance, so that an abnormal pressure rise at the start of the cycle If the valve opening set value is set low to suppress the pressure, the cycle must be operated with the valve opening set value lowered even during steady operation. Therefore, it is not possible to increase the pressure difference between the refrigeration cycle and the refrigeration cycle. Conversely, if the valve opening setting 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. There is.

Therefore, in the present invention, in a refrigeration cycle using a refrigerant having a low critical point such as carbon dioxide (co ₂ ), emphasis was 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 valve opening pressure of the relief device is different from the required pressure, the valve opening pressure of the relief device can be changed, and the sudden pressure rise 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 securing a capacity during a steady operation of the cycle. Disclosure of the invention

In order to achieve the above object, a refrigeration cycle according to the present invention includes a compressor that compresses a refrigerant to set a high-pressure line in a supercritical state according to operating conditions, and a radiator that cools the refrigerant compressed by the compressor. An expansion device for decompressing the refrigerant cooled by the radiator; an evaporator for evaporating the refrigerant decompressed by the expansion device; and a passage from the high-pressure line to the low-pressure line according to the refrigerant pressure of the high-pressure line. A valve for changing the communication between the high-pressure line and the low-pressure line. A high pressure sensing element that controls the movement of the valve body in response to the refrigerant pressure in the high pressure line; and a valve opening pressure adjustment that reduces the valve opening pressure of the valve body as the pressure in the low pressure line increases. And means are provided. 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 opened by the valve-opening pressure adjusting means. Since the valve pressure is reduced, high-pressure refrigerant can be relieved to the low-pressure line at an early stage when 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 at the time of the stoppage of the site, the valve opening pressure of the relief device is changed to a large value by the valve opening pressure adjusting means. At times, the pressure difference between the high pressure line and the low pressure line can be kept large. In other words, the valve opening pressure of the relief device can be varied by the pressure in the low-pressure line, so that sudden abnormal increase in pressure at startup can be avoided, and the required performance during steady-state operation is secured. 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 increases the urging force in the opening direction of the valve body that urges the high-pressure sensing element with the increase in the pressure in the low-pressure line. However, even if it is configured to have a low-pressure sensing element, a support for supporting the high-pressure sensing element is provided so as to be displaceable in the moving direction of the valve body, and the support for the high-pressure sensing element is supported on this support. The pressure receiving surface for receiving the pressure of the low pressure line may be provided on the side opposite to the side.

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 expansion and contraction direction 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 above configuration, the means for reducing the valve opening pressure of the valve element is added as the pressure in the low-pressure line increases, but without adding any special means. A configuration having the same valve opening pressure characteristics may be adopted. 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. An evaporator for evaporating the refrigerant decompressed by the expansion device, and a relief device for relieving 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, the relief device includes: a through hole that communicates the high pressure line side with the low pressure line side; a valve body that changes an opening degree of the through hole; A high-pressure pressure-sensitive element that controls the movement of the valve element in response to the refrigerant pressure, and the cross-sectional area of the through-hole and the valve element are attached to the high-pressure element. The ratio of the effective area of the portion receiving the force may be set so as to reduce the valve opening pressure of the valve body with an increase in pressure in the low pressure line _c Thus, in this configuration, the valve The opening is adjusted by the body.By adjusting the ratio between the area of the through hole and the effective area of the part where the valve is attached and receives the force from the high pressure sensing element, the biasing force that the valve itself receives from the low pressure side When 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), the valve opening pressure can be changed according to the However, the valve opening pressure decreases, and the high-pressure refrigerant can be relieved to the low-pressure line at the initial stage when the pressure in the high-pressure line increases. When the cycle starts and the pressure in the low pressure line drops below the pressure when the cycle is stopped, the valve opening pressure is changed to a large value. The difference 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. Becomes possible.

In the above configuration, the expansion device and the relief device are configured separately. The high-pressure sensing element may be formed by bellows.

A refrigeration cycle having such a relief device is suitable for a vapor compression refrigeration cycle in which the pressure in a high-pressure line can exceed the critical pressure of a refrigerant, for example, a refrigeration cycle using carbon dioxide as a refrigerant. Become. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a configuration example of a refrigeration cycle according to the present invention, and FIG. 2 is a cross-sectional view showing a specific configuration example of an expansion device and a relief device of the refrigeration cycle according to FIG. FIG. 3 is a diagram showing an example of the valve opening pressure characteristic of the relief device with respect to the expansion device outlet pressure P y, and FIG. 4 is a diagram showing the expansion device and the relief device shown in FIG. FIG. 5 is a cross-sectional view showing a modified configuration example of the relief device shown in FIG. 2 with respect to the configuration shown in FIG. 2, and FIG. Fig. 7 is a cross-sectional view showing an example of a configuration in which the inflation device and the relief device are integrated as shown in Fig. 7. Fig. 7 is 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 further replaced by another configuration with respect to the configuration shown in FIG. 2, and FIG. 10 is a sectional view showing the expansion device and the relief device shown in FIG. FIG. 4 is a cross-sectional view showing a configuration example in which a leaf device is integrated. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a refrigeration cycle 1 includes 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, and an expansion for decompressing the refrigerant. Device 5, evaporator 6 for evaporating and evaporating refrigerant, refrigerant flowing out of evaporator 6 It has an accumulator 7 for gas-liquid separation. 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 outlet side of the high-pressure passage 4a is connected to the expansion device 5. by connecting, the path to the expansion device 5 from the discharge side of the compressor 2 also _c is a high pressure line 8, the low pressure of the internal heat exchanger 4 to the outflow side of the expansion device 5 via the evaporator 6 and an accumulator 7 By connecting the outlet side of the low-pressure passage 4 b to the suction side (S) of the compressor 2, the path from the outlet side of the expansion device 5 to the compressor 2 is formed as a low-pressure line 9. I have. Further, in this cycle, the refrigerant is provided in parallel with the expansion device 5 and bypasses the expansion device 5 to transfer 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 for helicopter relief is provided.

As the refrigerant, a refrigerant having a low critical point, for example, carbon dioxide (co ₂ ) is used. The refrigerant compressed by the compressor 2 enters the radiator 3 as a high-temperature and high-pressure refrigerant, and radiates heat there. After cooling, the heat is exchanged with the low-temperature refrigerant flowing out of the evaporator 6 in the internal heat exchanger 4 to be cooled and sent to the expansion device 5 without being liquefied. The refrigerant that has reached the expansion device 5 is decompressed here to become low-temperature and low-pressure wet steam, exchanges heat with the air passing therethrough in the evaporator 6, and becomes gaseous. After the heat exchange with the high-temperature refrigerant in the line 8, the heat is returned to the compressor 2. Further, 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. I have.

FIG. 2 shows a specific configuration example of the inflation device 5 and the relief device 11. In this example, the inflation device 5 and the relief device 11 are formed separately from each other. The device 5 has a high-pressure space 16 and a low-pressure space 1Ί in a housing 15 configured by assembling housing members 15a and 15b. The pressure reducing valve 18 is disposed 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. In addition, the high-pressure space 16 and the low-pressure space 17 are communicated with each other through a through hole 20 of a partition wall 19 provided in one housing member 15b.

The pressure-reducing control valve 18 provided in the high-pressure space 16 includes a valve body 23 seated on a valve seat 22 formed on the peripheral portion of the through hole 20, and a rod 24 on the valve body 23. And a bellows 25 fixed to the top of the housing member 15a and joined together via a bellows 25, and according to the refrigerant environment (refrigerant pressure, refrigerant temperature) in the high-pressure space. The lift amount of the valve body 23 (the state of communication between the high-pressure space 16 and the low-pressure space 17) is adjusted.

On the other hand, the relief device 11 includes a high-pressure space 27 inside a housing 26 configured by assembling the nozing members 26 a, 26 b, 26 c, and one of the high-pressure space 27. And a second low-pressure space 29 formed on the other side of the high-pressure space 27, and a pressure regulating valve 30 is arranged in the high-pressure space 27. The second low-pressure space 29 is provided with an urging force adjusting member 31. In this example, the first low-pressure space 28 is formed in the housing member 26a, the high-pressure space 27 is formed by assembling the housing member 26a to the housing member 26b, The low-pressure space 29 is formed by assembling a housing member 26c at the bottom of the housing member 26b, and the high-pressure space 27 and the first low-pressure space 28 are The high-pressure space 27 and the second low-pressure space 29 are separated from each other by the bottom of the housing member 26 b without communication. ing.

The pressure control valve 30 disposed in the high-pressure space 27 is formed at the periphery of the through hole 33. And a bellows 3 接合 joined to the valve body 35 via a rod 36 and fixed to the bottom of the housing member 26 b. When the refrigerant pressure in the high-pressure space 27 exceeds a predetermined valve opening pressure of the bellows itself, the valve body 35 is lifted to move the high-pressure refrigerant from the high-pressure space 27 to the first low-pressure space. 2 to 8 heli reliefs. Further, the urging force adjusting member 31 arranged in the second low-pressure space 29 is fixed to the bottom of the housing member 26c, and the working medium is sealed therein to form the second low-pressure space 29. The bellows 38 contracts in the direction of expansion and contraction of the bellows 37 with the increase in pressure (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 a biasing port 39 that enters the high-pressure space 2 through the bottom of the housing member 26b. The biasing port 39 abuts against the bellows 37 of the high-pressure space 27 from the valve body 35 side, and biases the bellows 37 in a direction to contract, that is, the valve body 35 A biasing force can be supplied in the direction to decrease the valve opening pressure (valve opening direction).

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 the first space of the relief device 1 1 The 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 27 of the relief device 11 communicate with each other through a communication passage 42, and the low-pressure space 17 of the expansion device 5 and the second The low-pressure space 29 is communicated with the low-pressure space 29 by a communication passage 43.

Therefore, in the above-described configuration, when the pressure (low pressure) of the low pressure line 9 rises, the bellows 38 arranged in the second low pressure space 29 of the relief device 11 increase the low pressure pressure. And the urging force for contracting the bellows 37 arranged in the high-pressure space 27, that is, the urging force in the opening direction of the valve body 35 becomes large, and the relief device 11 The valve opening pressure decreases. On the other hand, low When the pressure in the pressure line 9 decreases, the bellows 38 disposed in the second low-pressure space 29 of the relief device 11 expands as the low-pressure pressure decreases, and moves to 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 becomes small, and the bellows 37 originally has the valve opening pressure of the relief device 11. It increases up to the specific valve opening pressure.

Therefore, the valve opening pressure of the relief device 11 can be changed by the bellows 3 8 which expands and contracts according to the low pressure, so that the valve opening pressure of the relief device 11 at the start of the cycle or during the steady operation of the cycle. Can be set appropriately. That is, by appropriately adjusting the type and amount of the working medium sealed in each of the bellows 37 and 38, the pressure at the outlet side of the expansion device 5 (expansion device outlet pressure) P y rises and P The required opening pressure of the relief device 11 when the cycle is stopped, which is 2, and the opening pressure of the relief device 11, which is required during steady-state operation when the expansion device outlet pressure Py decreases to P1 Since the relationship with the valve pressure Pa can be changed approximately linearly, for example, as shown in FIG. 3, the valve of the relief device 11 is opened when the cycle starts when the low pressure increases. Reducing the pressure PX to allow the refrigerant to escape from the high-pressure line 8 to the low-pressure line 9 at the initial stage when the high-pressure pressure starts to rise, mitigating the sudden rise in high-pressure pressure at the start of the cycle. It can be activated.

Also, 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 P x of the relief device 11 increases, and the cycle operation starts. Unnecessary relief in the refrigeration cycle can be avoided, and during the steady-state operation of the cycle, the pressure difference between the high-pressure line 8 and the low-pressure line 9 can be kept large to secure sufficient capacity of the refrigeration cycle 1. Become so.

In the above-described configuration, 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. No. That is, a high-pressure space 16 and a low-pressure space 17 forming the expansion device 5 are provided in the housing block 45, and a high-pressure space 27 and the first and second low-pressure spaces 2 forming the relief device 11 are provided. 8 and 29; a pressure reducing valve 18 in the high pressure space 16 of the expansion device 5; a pressure regulating valve 30 in the high pressure space 27 of the relief device 11; The high-pressure space 16 of 5 is connected to the high-pressure passage 4 a of the internal heat exchanger 4 via a pipe 40 connected to the housing block 45, and the first low-pressure space of the relief device 11 is connected. 28 and the second low-pressure space 29 are connected to the evaporator 6 via a passage 46 formed in the housing block 45 and a pipe 41 connected to the housing block 45, and an expansion device. The high-pressure space 16 of 5 and the high-pressure space 27 of the relief device 11 are connected by a communication passage 4 7 formed in the housing block 45. And it may be communicated by the low-pressure space 1 7 and a relief device 1 1 of the second communicating passage 4 8 a low-pressure space 2 9 formed in the housing proc 4 5 expansion device 5. In other respects, the configuration is the same as that shown in FIG. 2, and therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted. FIG. 5 shows an example of a configuration in which the above-described relief device 11 is modified. In this modified example, an urging force adjusting member 31 arranged in the second low-pressure space 29 of the relief device 11 is shown. Is fixed to the bottom of the housing member 26c, and the working medium is sealed therein, and contracts in the expansion and contraction direction of the bellows 37 as the pressure in the second low-pressure space is increased. 7) and an urging rod 39 fixed to the free end of the diaphragm 50 and entering the high-pressure space 27 through the bottom of the housing member 26b. It is configured. Other configurations are the same as those shown in FIG. 2, and therefore, the same portions are denoted by the same reference numerals and description thereof will be omitted.

Therefore, even in such a configuration, when the pressure (low pressure pressure) of the low pressure line 9 increases, the diaphragm 50 arranged in the second low pressure space 29 of the relief device 11 increases the low pressure pressure. To the high pressure space 27 Biasing force to try to arranged the base contracted rose 3 7, that is, the valve body 3 biasing force to open Direction of 5 increases, _c in which the valve opening pressure of the re-leaf device 1 1 becomes smaller On the other hand, when the pressure of 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 the high-pressure space 27 The urging force for contracting the bellows 37 housed in the valve body, i.e., the urging force in the opening direction of the valve body 35 becomes small, and the bellows 37 originally has the valve opening pressure of the relief device 11. To the specific valve opening pressure.

Therefore, even in such a configuration, the valve opening pressure of the relief device 11 can be changed by the diaphragm 50 that expands and contracts in accordance with the low pressure, so that the relief at the start of the cycle or during the steady operation of the cycle is possible. The valve opening pressure of the device 11 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 relief device 1 required when the cycle is stopped when the expansion device outlet pressure Py rises to P2. The relationship between the valve-opening pressure Pb of (1) and the valve-opening pressure Pa of the relief device 11 required during steady-state operation in which the outlet pressure Py of the expansion device is reduced to P1 is, for example, As shown in the figure, the pressure can be changed approximately linearly, so at the start of the cycle when the low pressure increases, the valve opening pressure of the relief device is reduced and the high pressure starts to increase at the initial stage. Refrigerant is released from the high-pressure line 8 to the low-pressure line 9 to mitigate a rapid rise in high-pressure pressure at the start of a cycle, and it is possible to start the sidal safely.

Also, 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 pressure decreases, so the valve-opening pressure of the relief device 11 increases. Unnecessary relief can be avoided during normal operation of the cycle, and the pressure difference between the high-pressure line 8 and the low-pressure line 9 can be kept large to ensure sufficient capacity of the refrigeration cycle 1. Swell.

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 the first and second low-pressure spaces 28 and 28 that constitute the relief device 11 are provided. 2 and 9; a pressure reducing valve 18 in the high-pressure space 16 of the expansion device 5; a pressure control valve 30 in the high-pressure space 27 of the relief device 11; The high pressure space 16 of the internal heat exchanger 4 is connected to the high pressure passage 4a of the internal heat exchanger 4 via a pipe 40 connected to the housing block 45, and the first low pressure space 28 and the second low pressure space 28 of the relief device 11 are connected. The low pressure space 29 is connected to the evaporator 6 via a passage 46 formed in the housing block 45 and a pipe 41 connected to the housing block 45, and the expansion device 5 The high-pressure space 15 and the high-pressure space 27 of the relief device 11 communicate with each other by a communication passage 47 formed in a housing block 45. A second low-pressure space 2 9 of the low-pressure space 1 7 Zhang apparatus 5 - relief device 1 1, may be communicated by the formation of. Communicating passage 4 8 was the housing Proc 4 5. 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 is omitted.

FIG. 7 shows a configuration showing another example of the relief device 11 _{c. In} this configuration example, the relief device 11 is configured by assembling the nodging members 55 a and 55 b. The bellows 56 is supported in a housing 55 formed as described above, and a movable body 57 movable in the expansion and contraction direction of the bellows 56 is housed. 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. It is slidably mounted on a cylindrical member 58 provided integrally inside 55 b, and is formed integrally with a pedestal 57 a supporting the bellows 56 and this pedestal 57 a Being cylindrical member 5 It has a ring-shaped part 57 b slidingly contacting the outer peripheral surface of the housing 8 and the inner peripheral surface of the housing member 55 a.

The inner surface of the housing member 5 5 a, ring-shaped portion 5 7 b abuts against the stopper 5 9 a and the pedestal portion 5 7 _a abuts a stop 5 9 b is formed, the tubular member 5 8, the housing member 5 5 An annular low-pressure space 60 is formed by the space surrounded by a, 55b and the ring-shaped portion 57b, and the portion of the ring-shaped portion 57b facing the low-pressure space 60 is the low-pressure space. The pressure receiving surface 61 receives the internal pressure. A high-pressure space 62 is formed by a space surrounded by the movable body 57 and the housing member 55a, and the high-pressure space 62 should be supported by the pedestal portion 57a. A rose 56 is fixed and received at the top of the housing member 55a.

The inside of the cylindrical member 58 communicates with the high-pressure space 62 through a communication hole 63 formed in the ring-shaped portion 57 b, and the movable member 57 inside the cylindrical member 58 A valve body 64 fixed to the pedestal portion 57 a of the valve body is suspended from the cylindrical member when the ring-shaped portion 57 b abuts against the stopper 59 a. The inside of 58 is squeezed to be seated on a valve seat 65 formed with a valve port. The pressure regulating valve 66 is constituted by the movable body 57, the bellows 56, and the valve body 64 described above, and when the movable body 57 is in contact with the stopper 59a, When the refrigerant pressure in the high pressure space 62 becomes equal to or higher than a predetermined valve opening pressure of the bellows 56 itself, the valve element 64 is lifted to move the high pressure refrigerant from the high pressure space 62 to the cylindrical member 58. It is designed to be relieved through the inside. Further, the lift of the valve body 64 is limited to a range until the pedestal portion 57a comes into contact with the stopper 59b, and the movable member 57 is moved from the cylindrical member 58 by the stopper 59b. It is secure. Since the inflation device 5 has the same configuration as the configuration shown in FIG. 2, the same portions are denoted by the same reference numerals and description thereof will be omitted.

The high-pressure space 16 of the expansion device 5 is connected to a pipe connected to the housing 15. It is connected to the high-pressure passage 4a of the internal heat exchanger 4 through 40, and the portion downstream of the valve seat 65 inside the cylindrical member 58 is connected to the evaporator 6 through piping 68. It is connected. The high-pressure space 16 of the expansion device 5 communicates with the high-pressure space 62 of the relief device 11 by a communication passage 69, and the low-pressure space 60 of the relief device 11 communicates with the low-pressure space of the expansion device 5. It is connected to the space 17 via the communication passage 67, and has a communication hole 9 9 formed in the cylindrical member 58 at a position downstream of the valve seat 65 inside the cylindrical member 58. Are communicated through.

Therefore, in the above-described configuration, when the pressure at the outlet of the expansion device (low pressure) Py increases, the pressure applied to the pressure receiving surface 61 of the ring-shaped portion 57 a increases, and the pressure in the direction of compressing the bellows 56 increases. The urging force increases and the valve opening pressure PX of the valve body 64 decreases. Conversely, when the pressure at the outlet of the expansion device (low pressure) P y decreases, the pressure applied to the pressure receiving surface 61 of the ring-shaped portion 57 a decreases, and the urging force in the direction of compressing the bellows decreases, thereby reducing the valve pressure. The valve opening pressure of the 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, as shown in FIG. 3, the relationship between the expansion device outlet pressure (low pressure pressure) P y and the valve opening pressure P x of the relief device 11 is represented by the pressure at the outlet side of the expansion device 5 (the expansion device). (Pressure at the outlet) Py rises to P2 Relief device required when the cycle is stopped 11 The valve opening pressure of Pb is set to Pb, and the expansion device outlet pressure Py is reduced to P1 for steady operation If the valve opening pressure of the relief device 11 required at that time is assumed to be Pa (Pa> Pb), and the linearity changes between the pressures as shown in Fig. 3, the expansion valve outlet side The relationship between the pressure P y and the valve opening pressure PX of the relief device can be expressed as PX + Py = K (constant). Therefore, assuming that the area of the pressure receiving surface 61 facing the low-pressure chamber 60 of the ring-shaped portion 57 b is Sr, and the effective area of the pedestal portion 57 a receiving the force from the bellows 57 is Sb, Due to the refrigerant pressure Py at the outlet of the expansion device, the urging force Fy received by the movable body 57 from the low-pressure space 60 becomes PySr. Assuming that the urging force received by the valve element 64 from the low pressure side is negligibly small, the valve opening pressure is reduced by approximately PySr / Sb, and the linear characteristic described above is reduced. In order to obtain it, it suffices to design so that Q! = Sr / Sb.

As described above, according to this configuration, it is only necessary to determine the characteristic to be obtained with the area ratio of Sr to Sb. For example, the valve is opened when Py in the steady cycle operation is 3 MPa. If the pressure PX is set to 14 MPa and the valve opening pressure PX is set to 12 MPa when Py at the cycle stop is 9 MPa, α = 1 3 = 1 5 (MPa), and by setting Sr to be 1Z3Sb, it is possible to set the valve opening pressure of the relief device at cycle start-up or during steady-state cycle operation properly. Becomes

Therefore, even in such a configuration, the valve opening pressure of the relief device 11 is reduced at the start of a cycle in which the low-pressure pressure increases, and the high-pressure line 8 changes to the low-pressure line 9 at an initial stage where the high-pressure pressure starts to increase. Since the refrigerant can be relieved, it is possible to alleviate a sudden increase in high pressure at the start of the cycle, and to start the cycle safely. Also, after a short period of operation of the cycle, the pressure difference between the high-pressure line 8 and the low-pressure line 9 increases, and the low-pressure pressure decreases, so the valve-opening pressure of the relief device 11 increases and the cycle operation starts. Unnecessary relief can be avoided in the air, and during the steady operation of the cycle, the pressure difference between the high-pressure line 8 and the low-pressure line 9 can be kept large to secure sufficient capacity of the refrigeration cycle 1. Become like

In the configuration shown in FIG. 7 described above, an example is shown in which the inflation device 5 and the relief device 11 are configured separately, but they may be integrated as shown in FIG. That is, a high-pressure space 16 and a low-pressure space 17 forming the expansion device 5 are provided in the housing block 70, and a high-pressure space 62 and a low-pressure space 60 forming the relief device 11 are housing-blocked. Cylindrical member provided at 70 The pressure reducing valve 18 is disposed in the high-pressure space 16 of the expansion device 5 and is defined by the movable member 57 attached to the cylindrical member 58. A bellows 56 is disposed in the space, and a valve body 6 is provided inside the cylindrical member 58, which is seated on a valve seat portion 65 protruding from the inner wall and moves integrally with the movable body 57. The high-pressure space 16 of the expansion device 5 communicates with the high-pressure space 62 of the relief device 11 via a communication passage 71, and the low-pressure space 17 of the expansion device 5 and the low-pressure space 60 of the relief device 11 and the cylinder. A portion of the housing member 58 on the downstream side of the valve seat portion 65 communicates with a passage 72 formed in the housing block 70 to connect the high-pressure space 16 of the expansion device 5 to the housing block 70. Via a pipe 40 connected to the high-pressure passage 4a of the internal heat exchanger 4, and a valve seat inside the cylindrical member 58.

A portion downstream from 65 may be connected to the evaporator 6 via a pipe 68. In other respects, the configuration is the same as that shown in FIG. 7, and therefore, 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 suitable for a case where the urging force received from the low pressure side of the valve body 64 is negligibly small, but as the bellows 56 becomes smaller, However, the urging force received from the low pressure side of the valve element 64 cannot be ignored. Therefore, in the configuration shown in FIG. 7, in order to obtain a substantially linear characteristic shown in FIG. 3, that is, a characteristic satisfying P _X + o; P y = K (constant), α is set to S r Should be set appropriately as the ratio between Sb and Sb (SrZSb), but if it is not possible to ignore the biasing force that the valve element receives from the low pressure side, the valve It is desirable to determine a in relation to the biasing force that the body receives from the low pressure side. 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. 9 has basically the same configuration as that of the inflation device 5, and includes a housing 7 formed by assembling the housing members 75 a and 75 b. High pressure space 7 6 and low pressure space 7 7 are provided in 5 The pressure space 76 is provided with a pressure control valve 78. In this example, the low-pressure space 77 is formed in one housing member 75b, and the high-pressure space 76 is formed by assembling one housing member 75b with the other housing member 75a. The high-pressure space 76 and the low-pressure space 77 are connected to each other through a through hole 80 of a partition wall 79 provided in one housing member 75b.

A pressure reducing valve 78 arranged in the high-pressure space 76 includes a valve element 83 seated on a valve seat 82 formed on the periphery of the through hole 80, and a rod 84 connected to the valve element 83. And a bellows 85 fixed to the top of the housing member 75a.The refrigerant pressure in the high-pressure space 76 is higher than a predetermined valve opening pressure of the bellows itself. When this happens, the valve element 83 is lifted so that the high-pressure refrigerant is relieved from the high-pressure space 76 to the low-pressure space 77.

The ratio (S 1 ZS 2) of the cross-sectional area S 1 of the through hole 80 to the effective area S 2 of the portion where the valve element 83 is attached and receives the force from the bellows 85 is described above. By setting it appropriately, as shown in Fig. 3, a substantially linear characteristic of reducing the valve opening pressure with an increase in the pressure in the low pressure line (outlet of the expansion device), that is, P x + a P y = K (constant).

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 space of the internal heat exchanger 4 through a pipe 40 connected to the housing 15. The low pressure space 77 of the relief device 11 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 76 of the relief device 11 are connected via a pipe 69, and the low-pressure space 17 of the expansion device 5 and the low-pressure space 7 of the relief device 11 are connected. 7 is connected via piping 87. Therefore, in the above-described configuration, when the pressure at the outlet of the expansion device (low pressure) Py increases, the pressure applied to the valve body 83 itself increases, and the urging force in the direction of compressing the bellows 85 increases. The valve opening pressure P _X of the valve element 83 decreases. Conversely, the pressure at the outlet of the expansion device (low pressure) P y When the pressure decreases, the pressure applied to the valve body 83 itself decreases, the urging force in the direction of compressing the bellows 85 decreases, and the valve opening pressure of the valve body 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 increases, and the refrigerant flows from the high pressure line 8 to the low pressure line 9 in the initial stage where the high pressure starts to increase. Can be easily escaped, so that a rapid rise in high-pressure pressure at the start of the cycle can be mitigated, and the cycle can be started safely. Also, after a short period of operation of the cycle, the pressure difference between the high-pressure line 8 and the low-pressure line 9 increases, and the low-pressure pressure decreases, so the valve-opening pressure of the relief device 11 increases and the cycle operation starts. Unnecessary relief can be avoided in the air, and during the steady operation of the cycle, the pressure difference between the high-pressure line 8 and the low-pressure line 9 can be kept large to secure sufficient capacity of the refrigeration cycle 1. Become like 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, so that the structure can be prevented from becoming complicated.

In the above-described configuration, 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. 10. A high-pressure space 16 and a low-pressure space 17 that constitute the expansion device 5 are provided in 0, and a high-pressure space 76 and a low-pressure space 77 that constitute the relief device 11 are provided. A pressure reducing valve 18 was arranged in 16 and a pressure adjusting valve 78 was arranged in the high-pressure space 76 of the relief device 11, and a high-pressure space 16 of the expansion device 5 was connected to the housing block 90. Connected to the high-pressure passage 4a of the internal heat exchanger 4 via the pipe 40, and connected the low-pressure space 77 of the relief device 11 to the passage 92 and the housing block 90 formed in the housing block 90. Connected to the evaporator 6 via the connected piping 6 8 and the expansion device 5 The high-pressure space 16 communicates with the high-pressure space 76 of the relief device 11 by a communication passage 93 formed in the housing block 90, and the low-pressure space 17 of the expansion device 5 and the low-pressure space of the relief device 11 are connected. It is also possible to communicate with the housing block 90 by a communication passage 94 formed in the housing block 90. Other configurations are the same as those shown in FIG. 9, and therefore, the same portions are denoted by the same reference numerals and description thereof is omitted.

Note that, in each of the above configuration examples, an example in which a bellows-type pressure control valve is used as the relief device 11 has been described, but a diaphragm-type pressure control valve may be used. In addition, in each configuration example, an arbitrary point of the low-pressure line 9 where the pressure from the expansion device outlet side is directly introduced into the low-pressure chambers 29, 60, and 77 of the relief device 11 is shown. The low pressure may be derived from the pressure. Industrial applicability

As described above, according to the present invention, the 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 changes the communication state between the high pressure line and the low pressure line. Valve element, a high-pressure sensing element that controls the movement of the valve element in response to the refrigerant pressure in the high-pressure line, and valve-opening pressure adjusting means that reduces the valve opening pressure of the valve element as the pressure in the low-pressure line increases. Or the ratio of the area of the through hole whose opening is adjusted by the valve element to the effective area of the portion to which the valve element is attached and receives the force from the high-pressure pressure-sensitive element is set. By adjusting the pressure, the valve opening pressure of the valve body was reduced as the pressure in the low pressure line increased, so if the refrigeration cycle stopped and the pressure in the low pressure line increased (the pressure in the high pressure line and the low pressure line Close to the pressure of In this case, the valve opening pressure of the relief device can be reduced, and the sudden increase in pressure at the start of the cycle can be mitigated to allow the cycle to operate safely.

Also, when the cycle starts and the pressure in the low pressure line decreases, the relief Since the valve opening pressure of the device can be changed to a large value, the pressure difference between the high pressure line and the low pressure line can be kept large, and the cooling capacity can be secured during the steady operation of the cycle Become like

As a specific mode of the valve-opening pressure adjusting means, it expands and contracts in response to the refrigerant pressure in the low-pressure line, and increases the urging force in the valve-opening direction, which urges the high-pressure pressure-sensitive element as the pressure in the low-pressure line increases. However, even if it is configured to have a low-pressure sensing element such as a bellows or a diaphragm, a support for supporting the high-pressure sensing element is provided so as to be displaceable in the moving direction of the valve body, and a high-pressure sensing element is provided for this support. 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 pressure element. With such a configuration, the valve-opening pressure originally possessed by the high-pressure pressure-sensitive element itself can be adjusted to this value. It can be easily changed by changing the urging force applied to the high-pressure pressure-sensitive element.

Claims

The scope of the claims

1. 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 radiator that cools the refrigerant. An expansion device for reducing the pressure of the refrigerant, an evaporator for evaporating the refrigerant reduced in pressure by the expansion device, and a relief device for relieving the refrigerant from the high-pressure line to the low-pressure line in accordance with the refrigerant pressure of the high-pressure line. In a refrigeration cycle configured at least,

The relief device,

A valve body that changes a communication state between the high-pressure line and the low-pressure line; a high-pressure pressure-sensitive element that controls movement of the valve body in response to a refrigerant pressure of the high-pressure line;

A refrigeration cycle comprising: valve opening pressure adjusting means for reducing the valve opening pressure of the valve element in accordance with an increase in the pressure of the low pressure line.

2. The valve-opening pressure adjusting means expands and contracts in response to the refrigerant pressure in the low-pressure line, and applies a pressure in the opening direction of the valve body that urges the high-pressure sensing element as the pressure in the low-pressure line increases. 2. The refrigeration cycle according to claim 1, wherein the refrigeration cycle is configured to include a low-pressure pressure-sensitive element for increasing power.

3. The refrigeration cycle according to claim 2, wherein the low-pressure sensing element is constituted by a bellows that can expand and contract in a direction in which the high-pressure sensing element expands and contracts in accordance with the refrigerant pressure in the low-pressure line.

3. The refrigeration cycle according to claim 2, wherein the low-pressure sensing element is constituted by a diaphragm that can expand and contract in a direction in which the high-pressure sensing element expands and contracts in accordance with the refrigerant pressure in the low-pressure line.

5. The valve opening pressure adjusting means includes: a movable body that supports the high-pressure sensing element is provided 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 a holding side.

6. 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 radiator that cools the refrigerant. An expansion device for reducing the pressure of the refrigerant, an evaporator for evaporating the refrigerant reduced in pressure by the expansion device, and a relief device for relieving the refrigerant from the high-pressure line to the low-pressure line according to the refrigerant pressure in the high-pressure line. In a refrigeration cycle configured at least,

The relief device,

A through-hole communicating the high-pressure line side and the low-pressure line side,

A valve element for changing the opening of the through hole;

A high-pressure pressure-sensitive element that controls the movement of the valve body in response to the refrigerant pressure in the high-pressure line,

The ratio of the cross-sectional area of the through hole to the effective area of the portion where the valve element is attached and receives the force from the high pressure sensing element is reduced as the pressure in the low pressure line increases. A refrigeration cycle characterized in that:

7. The refrigeration cycle according to claim 1, wherein the expansion device and the relief device are configured separately.

8. The refrigeration cycle according to claim 1, wherein the expansion device and the relief device are integrated.

9. The refrigeration cycle according to claim 1, wherein the high-pressure pressure-sensitive element is constituted by a bellows.

10. The refrigeration cycle _{c according to} claim 1 or 6, wherein the refrigerant is carbon dioxide.