WO2001006183A1

WO2001006183A1 - Refrigerating cycle

Info

Publication number: WO2001006183A1
Application number: PCT/JP2000/004324
Authority: WO
Inventors: Nobuhiko Suzuki; Shunichi Furuya; Yuji Kawamura; Shunji Muta; Kenji Iijima; Sakae Hayashi; Hiroshi Kanai; Akihiko Takano; Hajime Mukawa
Original assignee: Zexel Valeo Climate Control Corporation
Priority date: 1999-07-16
Filing date: 2000-06-30
Publication date: 2001-01-25

Abstract

A refrigerating cycle using a refrigerant having a low critical point such as CO2, wherein first and second valve discs (23, 27) making a communication state vary between an inlet side passage part (11) and an outlet side passage part (12), a first bellows (25) having carbon dioxide sealed therein and controlling the movement of the first valve disc (23) according to a refrigerant temperature or a refrigerant pressure on a radiator side, and a second bellows (29) having inert gas sealed therein and controlling the movement of the second valve disc (27) according to the refrigerant pressure on the radiator side are provided in an expansion device (5) of the refrigerating cycle, leak means which, in the state that the communication state of the communication passages is minimized by the valve disc, leaks the refrigerant from the inlet side passage part (11) to the outlet side passage part (12) may be provided in the expansion device (5), whereby a smooth operation from the state of having been left in high temperature atmosphere is assured, a pressure resistant design value of each component constituting the refrigerating cycle is lowered, and each component is reduced in size and weight, and thus an intermittent variation of cycle at a low load can be avoided.

Description

Specification

Refrigeration cycle technology

The present invention, refrigerant low critical point as the refrigerant, for example, about the carbon dioxide (C 0 ₂₎ refrigeration cycle using the available refrigerant in the supercritical region as such. Background art

As a refrigeration cycle using carbon dioxide (C 0 ₂ ) as a refrigerant, a configuration disclosed in Japanese Patent Application Laid-Open No. 9-246462 is known. The pressure control valve controls the pressure on the outlet side of the radiator by a pressure control valve. The pressure control valve is formed in a coolant flow path, and partitions the coolant flow path into an upstream space and a downstream space. A partition wall portion, a valve port formed in the partition wall portion, for communicating the upstream space and the downstream space, and a closed space formed in the upstream space, in response to a pressure difference between the inside and outside of the closed space. A displacement member that displaces the valve port, and a valve body that opens and closes the valve port. The displacement member is displaced when the pressure in the upstream space becomes larger than the pressure in the closed space by a predetermined amount. The valve body is configured to open the valve port when the displacement member is displaced.

Further, this publication, the density carbon dioxide in the sealed space ^{4 5 0 K g / m 3} ~ 9 5 0 K / m 3 (6 0 0 K g / m 3 in the embodiment) of the pressure control valve By enclosing, the pressure on the high pressure side is detected, and this pressure is controlled to be the target pressure, and the pressure on the outlet side of the radiator is controlled along the optimal control line shown in the same publication. Points are also shown.

According to such a pressure control valve, when the pressure on the outlet side of the radiator increases, the displacement portion is displaced by the pressure difference between the pressure of the refrigerant sealed in the enclosed space. Since the material is displaced and the valve body is moved in the direction to open the valve port, the outlet side pressure is reduced, and when the refrigerant temperature on the outlet side of the radiator is high, the refrigerant in the closed space is When the expansion member expands, the displacement member is displaced to move the valve body in a direction to close the valve port, so that the pressure on the outlet side of the radiator increases, and the outlet of the radiator does not increase the compression work of the compressor. The side pressure can be increased, and the cooling capacity can be secured while suppressing the deterioration of the coefficient of performance of the refrigeration cycle.

However, in the above-described refrigeration cycle, since the gas sealed in the pressure control valve uses the same carbon dioxide gas as the refrigerant, the following inconvenience is expected to occur.

In other words, when the air conditioner is started while the vehicle is left in an environment where the outside temperature is high, such as in summer, the temperature in the engine room is extremely high at 55 ° C (up to 60 ° C). Also, the temperature of the gas filled in the pressure control valve has risen to that temperature. For example, when the operating characteristics of the expansion valve are as shown by the broken line in FIG. If the pressure does not rise to ~ 19 MPa, the expansion valve will not open, which means that when the air conditioner is started, the refrigerant temperature is high and the refrigerant cooled by the radiator is not flowing, so the pressure control Since the gas enclosed in the enclosed space of the valve cannot be cooled, the pressure control valve keeps the valve closed in order to maintain a high pressure, so the maximum pressure allowed during normal operation Power (about 15MPa) If the maximum operating pressure is set to a high pressure switch so as not to exceed this pressure, and if measures such as stopping the compressor are taken if the pressure exceeds 15 MPa by this switch, However, the high pressure side pressure becomes too high at the time of starting and exceeds the design allowable pressure, and the high pressure cut switch frequently operates.

Further, the variable displacement compressor using carbon dioxide (C 0 ₂₎ Cycle In such cases, the following phenomena have been confirmed by the present applicant. That is, if C 0 ₂ cycle is operated at low load, that is, your information, the ejection amount and the radiator of the compressor when the refrigerant pressure in the high pressure line is operated in a subcritical region to be lower than the critical pressure Even when the load on the condenser is constant (environmental conditions are constant), the refrigeration cycle intermittently fluctuates in a steady operation state.

Various causes have been estimated for the occurrence of this phenomenon, but the main causes are considered as follows.

That is, regardless of whether it is a diaphragm type expansion valve or a bellows type expansion valve, the gas sealed in the expansion valve expands or contracts according to the refrigerant temperature on the expansion valve inlet side, and the position of the valve body is increased. Is displaced, and the position of the valve element is displaced even in response to the refrigerant pressure on the expansion valve inlet side, so that the sealed gas is filled so that the relationship between the refrigerant temperature and the refrigerant pressure has optimal control characteristics. Thus, the opening degree of the expansion valve becomes the target opening degree according to the refrigerant temperature on the inflow side / refrigerant pressure.

However, at low load, if a variable capacity compressor is used as the compressor, the discharge volume will be reduced originally, so the pressure in the high pressure line will be relatively low and the expansion valve will close. Work in the direction. In particular, at such a low load, when the opening degree of the expansion valve is stable at a position where the optimum refrigerant pressure P is obtained for a certain refrigerant temperature T, the refrigerant temperature becomes T for some reason. If it is higher, the expansion valve will close.

Then, the amount of the refrigerant supplied to the low-pressure line via the expansion valve decreases. Currently, variable displacement compressors are designed to control the discharge rate according to the low pressure.The discharge rate is low when the low pressure is low, and the discharge rate is high when the low pressure is high. Control is performed As the amount of refrigerant supplied to the low-pressure line decreases, the discharge amount of the compressor also decreases. When the discharge rate of the compressor decreases, at low load where the cycle operates in the subcritical region, the action of reducing the volume of the refrigerant by the condensing action of the radiator is smaller than the action of increasing the capacity of the refrigerant by the compressor. As a result, the refrigerant pressure on the high pressure side does not rise for a while, and the closed state of the expansion valve is maintained.

Even in such a state, the compressor continues to discharge the refrigerant little by little to the high pressure side. Therefore, the operation of increasing the volume by the refrigerant discharged from the compressor is superior to the operation of reducing the volume of the refrigerant by the condensation action of the radiator, and the high pressure gradually increases. Then, when the high pressure required for the cooling valve is reached, the expansion valve opens and the high-pressure side refrigerant flows to the low-pressure side at a stretch. Occurs. It is considered that such a series of operations is repeated thereafter, so that the cycle intermittently fluctuates greatly.

Hunting at such a low load (when the stroke of the compressor is small), as shown in Fig. 16, the hunting cycle reaches 150 to 250 seconds, and most of the hunting period occurs. During the period during which the expansion valve is closed, the temperature of the refrigerant at the outlet side of the evaporator rises significantly during this time, and a large amount of refrigerant flows into the evaporator during the short period when the expansion valve opens, and Refrigerant temperature at outlet side drops rapidly. As a result, the temperature of the air passing through the evaporator while the expansion valve is closed rises by about 15 ° C, and the temperature of the air passing through the evaporator sharply decreases during the short period when the expansion valve opens. As a result, it has been recognized that the temperature of the blown air fluctuates greatly with the hunting of the cycle described above. Therefore, in the present invention, the carbon dioxide (C 0 ₂₎ refrigeration cycle using a low There refrigerant critical points, such as a primary object to ensure smooth cycle operation from such a state was left at a high temperature ambient air It also aims to reduce the pressure-resistant design value of each component that makes up the refrigeration cycle, and to make each component smaller and lighter.

Further, in the present invention, in a refrigeration cycle using a low There refrigerant carbon dioxide (C 0 ₂₎ critical points, such as, suppressing the cyclic variation in the low load that may occur intermittently, i.e., low load Another object of the present invention is to provide a refrigeration cycle that can avoid the continuation of the closed state of the expansion device at the same time. 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. In a refrigeration cycle including at least an expansion device that decompresses the refrigerant cooled by the radiator and an evaporator that evaporates the refrigerant depressurized by the expansion device, the expansion device includes a radiator side. An inlet-side passage communicating with the evaporator; an outlet-side passage communicating with the evaporator; and an inlet-side passage and the outlet-side passage provided between the inlet-side passage and the outlet-side passage. The first and second valve bodies that change the communication state between the first and second valves and carbon dioxide gas are sealed therein to detect the refrigerant condition on the radiator side. And refrigerant temperature) A first sensing element for controlling the movement of the first valve element and an inert gas sealed therein to sense the refrigerant pressure on the radiator side, and according to the refrigerant pressure on the radiator side, The second sense controlling the movement of the second valve body And a receiving element.

Therefore, the inert gas sealed in the second sensing element has a characteristic of contracting when the refrigerant pressure on the radiator side of the expansion device reaches a predetermined pressure, regardless of the refrigerant temperature. Therefore, when the refrigerant temperature is low, the first sensing element filled with the carbon dioxide gas first contracts to open the first valve body, and the communication between the inlet-side passage portion and the outlet-side passage portion is established. However, when the refrigerant temperature is high, the first valve body is difficult to open, but the second valve body filled with the inert gas opens first, and the space between the inlet-side passage portion and the outlet-side passage portion is increased. Can be communicated. In other words, even when the refrigeration cycle is started while being left at a high temperature, the relatively low temperature refrigerant cooled by the radiator can flow through the expansion device by opening the second valve body, and the refrigerant temperature gradually decreases. When the pressure drops, the first valve element begins to function, and control of the communication state between the inlet-side passage and the outlet-side passage can be shifted from the second valve to the first valve. In addition, the expansion device of the refrigeration cycle described above includes an inlet-side passage portion communicating with the radiator side, an outlet-side passage portion communicating with the evaporator side, the inlet-side passage portion, and the outlet-side passage portion. And a valve body that changes the communication state of the communication path formed between the valve body and a gas such as carbon dioxide gas is sealed inside to sense the refrigerant condition on the radiator side, and responds to the refrigerant condition on the radiator side. A sensing element for controlling the movement of the valve body, A leaking means for leaking refrigerant from the inlet-side passage to the outlet-side passage in a state where the communication state of the communication passage is minimized by the valve body between the outlet-side passage and the outlet-side passage. It may be configured.

According to such a configuration, even when the refrigerant temperature at the time of starting is high and the communication path minimizes the communication state by the valve element, for example, when the communication path is closed, the refrigerant leaks. Flow from the inlet side passage to the outlet side passage through the means, the low temperature refrigerant cooled by the radiator is expanded At the stage when the refrigerant gas can be cooled and the temperature of the refrigerant gradually decreases to allow the expansion device to function normally. Thus, the communication between the inlet-side passage and the outlet-side passage is controlled by the valve body as usual. In addition, the provision of the leak means supplies the refrigerant to the low-pressure side by the leak means even if the expansion device is closed during steady operation at low load (even if the valve element is seated on the valve seat). It is possible to prevent the disadvantage that the discharge capacity of the compressor is reduced by suppressing the reduction of the low pressure, thereby enabling the pressure on the inflow side of the expansion device to be increased at an early stage, and the expansion device to be mounted quickly. Opening is encouraged, and the inconvenience of large intermittent cycle fluctuations can be suppressed.

Here, even if the leak means is an orifice formed between the inlet-side passage portion and the outlet-side passage portion, it is constituted by providing a clearance (clearance) between the valve body and the communication passage. Or a groove formed in the valve body or a groove formed in the valve seat on which the valve body sits.

When the leak means is configured with an orifice, the orifice is in a range where subcooling (SC) can occur due to the need to secure sufficient refrigeration efficiency, and can prevent the expansion device from being clogged and clogged. 0.3 mn in diameter to prevent ball It is preferable to set the diameter in the range of ~ 1.5 mm, more preferably in the range of about 0.3-0.5 mm. In the case where the leak means is formed with a gap (clearance) between the valve body and the communication passage, or in the case where the leak means is formed by forming a groove in the valve body or the valve seat, the refrigerant flows through the gap (clearance) or the groove. The total cross-sectional area of the leaking part is preferably about 0.07 to 0.20 mm ² (corresponding to the cross-sectional area of a hole having a diameter of 0.3 to 0.5 mm). Further, instead of the orifice, another communication passage communicating between the inlet-side passage and the outlet-side passage is provided separately from the communication passage, and the pressure of the inlet-side passage is provided in the other communication passage. May be provided with a relief valve that opens when the pressure exceeds a predetermined pressure.

According to such a configuration, even when the refrigerant temperature at the time of startup is high and the communication passage is closed by the valve body, the relief valve is opened when the high pressure exceeds a predetermined pressure. Since the refrigerant flows from the inlet-side passage to the outlet-side passage, the relatively low-temperature refrigerant cooled by the radiator can flow to the expansion device, and is thereby sealed in the sensing element of the expansion device. Gas can be cooled and the temperature of the refrigerant gradually decreases, and the expansion device can function normally.At this stage, the communication between the inlet-side passage and the outlet-side passage is established by the valve element. It will be controlled as usual. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a diagram showing a configuration example of a refrigeration cycle according to the present invention using a supercritical refrigerant as a refrigerant. FIG. 2 is an enlarged sectional view of the expansion device of the refrigeration cycle according to FIG. Figure 3 is a first pressure reducing and regulating valve, the relationship between the refrigerant temperature and the refrigerant pressure at the expansion device inlet side of the second pressure reducing control valve which is filled with an inert gas sealed carbon dioxide (C 0 ₂₎ FIG. FIG. 4 is an enlarged cross-sectional view showing a configuration example using a diaphragm type expansion device and an orifice as a leak means. FIG. 5 is an enlarged sectional view showing a modification of the expansion device shown in FIG. FIG. 6 shows the relationship between the refrigerant temperature and the refrigerant pressure at the expansion device inlet side of the conventional expansion device, the expansion device with an orifice shown in FIG. 4, and the expansion device with a relief valve shown in FIG. FIG. 6 is a characteristic diagram. FIG. 7 is an enlarged sectional view showing a bellows-type inflator in place of the diaphragm type in FIG. Figure 8 shows PT /

9

FIG. 8 is an enlarged sectional view showing a modification of the expansion device shown in FIG. FIG. 9 is a characteristic diagram showing a change in subcooling with respect to the diameter of the orifice. FIG. 10 is an enlarged view of the vicinity of a valve body showing a configuration example in which a groove is formed in a spherical valve body as a leak means. FIG. 11 is an enlarged view of the vicinity of a valve seat showing a configuration example in which a groove is formed in a valve seat on which a spherical valve element is seated as a leak means. Fig. 12 shows an example of a configuration in which a groove is formed in a 21 dollar-shaped valve body as a leak means, (a) is a view showing a state where the valve body is seated on a valve seat, and (b) is a view showing It is an expansion perspective view of a valve body. FIG. 13 is an enlarged view of the vicinity of a valve seat showing a configuration example in which a groove is formed in a valve seat on which a needle-shaped valve element is seated as a leak means. FIG. 14 is a diagram showing a configuration example in the case of using a spool-shaped valve body as a leak means. FIG. 15 is an explanatory view for explaining the spool-shaped valve element shown in FIG. 14, in which (a) is a view of the valve element viewed from the side, and (b) is (a). FIG. 3 is a cross-sectional view taken along line 15B--15B of FIG. FIG. 16 is a diagram showing the temporal change of the refrigerant temperature at the outlet side of the evaporator in order to explain the state of the conventional hunting. The first 7 figures total cross-sectional area of about 0.1 2 5 6 cycles hunting when set as mm ² of the first leak portion with a valve body of the needle shape shown in Figure 2 the valve body of the expansion device FIG. 4 is a diagram showing a temporal change of a refrigerant temperature on an outlet side of an evaporator in order to explain the state of FIG. 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 a 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 4, and a pressure reduction for the refrigerant. It comprises an expansion device 5, an evaporator 6 for evaporating and evaporating the refrigerant, and an accumulator for gas-liquid separation of the refrigerant flowing out of the evaporator 6. In this cycle, the discharge side (D) of the compressor 2 is connected via the radiator 3 Connected to the high-pressure passage 4a of the internal heat exchanger 4, the outlet side of the high-pressure passage 4a is connected to the expansion device 5, and the path from the discharge side of the compressor 2 to the expansion device 5 is a high-pressure line 8. . The outlet side of the expansion device 5 is connected to the evaporator 6, and the outlet side of the evaporator 6 is connected to the low-pressure passage 4 b of the internal heat exchanger 4 via the accumulator 7. The outflow side of the low-pressure passage 4 b is connected to the suction side (S) of the compressor 2, and the path from the outflow side of the expansion device 5 to the compressor 2 is a low-pressure line 9.

In this refrigeration cycle 1, a low critical point refrigerant as a refrigerant, For example, carbon dioxide (C 0 ₂₎ is used and refrigerant compressed by the compressor 2, radiator 3 as a high-temperature high-pressure refrigerant Then, heat is radiated and cooled here. Then, the internal heat exchanger 4 exchanges heat with the low-temperature refrigerant flowing out of the evaporator 6 to be further cooled and sent to the expansion device 5 without being liquefied. Then, the pressure is reduced in the expansion device 5 to become low-temperature and low-pressure wet steam, and heat exchange with the air passing therethrough in the evaporator 6 to form a gaseous state. It is heated by exchanging heat with the refrigerant and returned to the compressor 2.

As shown in FIG. 2, the expansion device 5 communicates with the housing 10 through the high-pressure passage 4 a of the internal heat exchanger 4 (which communicates with the radiator side). And a high-pressure space 13 where these passages are opened. The first and second pressure-reducing control valves 14 and 15 are housed in the high-pressure space 13. .

The high-pressure space 13 is defined by the boundary wall 16 into two control valve storage spaces 17 and 18, and these two control valve storage spaces 17 and 18 are through holes formed in the boundary wall 16. The control valve storage space 17 has an opening on the inlet side passage 11 and a first communication passage 20 communicating with the outlet side passage 12 on the other side. The space 18 communicates with the exit passageway 1 2 The second communication passage 21 is open.

A first pressure reducing control valve 14 is stored in one control valve storage space 17, and the first pressure reducing control valve 14 opens to the high pressure space 13 of the first communication passage 20. The valve body 23 includes a valve body 23 seated on a valve seat 22 formed in an opening portion, and a first bellows 25 joined to the valve body 23 via a rod 24. Rose 2 5 predetermined amount of carbon dioxide in the (C 0 ₂₎ is that is sealed. A second pressure reducing control valve 15 is stored in the other control valve storage space 18. The second pressure reducing control valve 15 is similar to the first pressure reducing control valve 14.

A valve body 27 seated on a valve seat 26 formed at an opening portion of the communication passage 21 of the second 2 opening to the high-pressure space 13, and a valve body 27 joined to the valve body 27 via a rod 28. The second bellows 29 is filled with a predetermined amount of inert gas.

The valve pressures of the first and second pressure reducing valves 14 and 15 and the movement of the valve bodies 23 and 27 are adjusted by changing the amount of gas filled in the bellows. 14 and 15 respond to the pressure of the high-pressure space 13 and the refrigerant temperature around the bellows, and the characteristics of the refrigerant temperature and the refrigerant pressure at the expansion device inlet are shown in Fig. 3. That is, the first pressure-reducing control valve 14 filled with carbon dioxide gas (C 0 ₂ ) almost linearly expands at the expansion device inlet as the refrigerant temperature rises. While the refrigerant pressure has the characteristic of rising, the inert gas

The pressure-reducing control valve 15 of 2 has such a characteristic that the refrigerant pressure at the expansion device inlet is substantially constant irrespective of the expansion device inlet refrigerant temperature.

In the above configuration, when the refrigeration cycle that has been left under high-temperature outside air starts, the temperature of the refrigerant at the inlet of the expansion device and the temperature of the charged gas in the bellows are high, and the first pressure reducing valve 14 Alone would require an unusually high pressure to open the first valve element 23, creating a force switch. There is an inconvenience of moving. However, as described above, since the second pressure reducing valve 15 filled with an inert gas that depends only on the pressure is provided in parallel, even if the temperature at the start of the cycle is high, the predetermined set pressure can be obtained. When this occurs, the second valve element 27 is opened, so that the refrigerant radiated by the radiator 3 passes through the through hole 19 from one valve element storage space 17 of the expansion device 5 and the other valve element. Since the gas flows into the storage space 18 and then flows through the second communication passage 21 to the outlet-side passage portion 12, a smooth cycle operation at the time of starting can be ensured.

Thereafter, when the temperature of the refrigerant passing through the expansion device 5 decreases, the first pressure-reducing control valve 14 is activated, and the pressure is reduced. 15 closes and shifts to normal pressure reduction control.In other words, where the refrigerant temperature is higher than A in the characteristic line shown in FIG. 3, the second pressure reduction control valve 15 shown by the solid line functions, and Also, when the refrigerant temperature is low, the first pressure-reducing control valve 14 shown by the broken line functions.In addition, according to such a configuration, not only at the time of starting the cycle, but also the vehicle accelerates rapidly. Even in the case where the high-pressure side pressure suddenly rises due to an increase in the rotation speed of the compressor, as in the case, etc., the second communication passage 21 is opened by the operation of the second pressure reducing control valve 15, and the refrigerant To the low pressure side, the operation of the high pressure cutter switch can be avoided, ONZOFF of the compressor due to frequent operation of the high-pressure cut switch can be avoided, and deterioration of air conditioning feeling can be prevented.

Furthermore, since the first pressure reducing control valve 14 is arranged upstream of the second pressure reducing valve 15, the refrigerant around the first pressure reducing valve 14 always starts when a cycle in which the refrigerant temperature is high is started. Flow, the cooling of the first pressure reducing valve 14 is promoted, and the time until the first pressure reducing valve 14 operates normally can be shortened. 15 to 1st decompression The transition to the node valve 14 can be promptly performed, and the operations of the two pressure reducing control valves 14 and 15 can be smoothly connected. Moreover, since the two pressure-reducing control valves 14 and 15 are provided integrally with the expansion device 5, it is not necessary to secure a space by separating them, and the cost is also advantageous, and the allowable pressure resistance is reduced. Since it is not necessary to increase the size, the withstand voltage design value of each component can be reduced, and as a result, each component can be reduced in size and weight.

FIG. 4 shows another configuration example of the present invention. In this example, a diaphragm type pressure reducing control valve 30 is housed in a high pressure space 13 of an expansion device 5. A communication passage 31 is formed between the high-pressure space 13 and the outlet-side passage portion 12, and the pressure reducing control valve 30 is housed in the valve holder 32 and the high-pressure space 13 of the communication passage 31 is formed. A valve body 34 seated on a valve seat 33 formed in an opening portion opened to the outside, and a diaphragm 36 joined to the valve body 34 via a load 35 valve holder 3 2 has a passage portion 37 communicating the storage portion of the valve element 34 with the high-pressure space 13 and a rod 35, and communicates with the passage portion 3 7 on the rod-side surface of the diaphragm 36. A passage portion 38 for guiding the refrigerant in the high-pressure space is formed, and a spring 40 is elastically mounted between a panel receiver 39 formed in the valve holder 32 and the valve body 34, and a valve body 3 is provided. 4 is constantly urged in a direction to close the communication passage 31. In addition, the diaphragm 36 is sandwiched and fixed between the valve holder 32 and the valve cover 41, and a sealed space 42 is formed by the valve cover 41 and the diaphragm 36. Determination of carbon dioxide (C 0 ₂₎ is sealed entrance. In the vicinity of the pressure-reducing control valve 30, a leak means for leaking the refrigerant from the inlet-side passage portion 11 to the outlet-side passage portion 12 is provided. The orifice 43 is formed to communicate with the outlet side passage portion 12. The orifice 43 is formed downstream of the pressure-reducing control valve 30 with respect to the inlet-side passage portion 11. You. Since other configurations are the same as those of the above configuration example, the same portions are denoted by the same reference numerals and description thereof will be omitted.

In such a configuration, since the refrigerant flowing from the more orifice 4 3 high pressure increases to the low pressure side is increased, controlled the cycles by the carbon dioxide (C 0 ₂₎ only sealing vacuum regulating valve 3 0 off to Compared to the conventional one (indicated by the broken line in Fig. 6), in this configuration with an orifice further, the slope between the refrigerant temperature and the refrigerant pressure at the inlet of the expansion device has a smaller slope as shown by the dashed line in Fig. 6. As a result, even if a refrigeration cycle that has been left under high-temperature outside air starts, it is possible to suppress the high-pressure pressure, and the high-pressure cut switch is frequently activated, thereby turning off the compressor. Can be avoided, and deterioration of the air conditioning filling can be prevented.

Also, the orifice 43 is provided downstream of the pressure-reducing control valve 30, and when the refrigerant temperature is high, the refrigerant flows from the high-pressure space 13 through the orifice 43 to the outlet side passageway 12. However, the refrigerant radiated by the radiator 3 flows around the pressure-reducing control valve 30, and cooling of the pressure-reducing control valve 30 can be promoted. Thereafter, when the temperature of the refrigerant passing through the expansion device 5 decreases, the pressure-reducing control valve 30 that has been closed is opened, and the normal pressure-reducing control can be performed. We can guarantee it.

Furthermore, since the allowable withstand voltage does not need to be increased, the withstand voltage design value of each component can be reduced, and as a result, each component can be reduced in size and weight, such as when the vehicle suddenly accelerates. Thus, even when the number of revolutions of the compressor increases and the high-pressure side pressure sharply increases, it is possible to cope with the same as in the above configuration example.

In particular, according to the orifice 43 of this configuration, the valve element 34 is seated on the valve seat 33. Even in such a case, the refrigerant can leak from the high pressure side to the low pressure side, so that a variable capacity compressor whose capacity is controlled by the pressure of the low pressure line is used as the compressor and In operation in a low-load region where the valve operates in a subcritical region below the critical pressure, even when the valve element of the expansion device sits on the valve seat and closes the communication passage 31, the Since the refrigerant can be supplied to the low-pressure side via 43, it is possible to suppress a remarkable decrease in the low-pressure pressure and a remarkable decrease in the discharge amount of the compressor, and avoid the phenomenon that the refrigerating cycle intermittently fluctuates greatly. Can o

FIG. 5 shows still another configuration example of the present invention. This configuration example is different from the configuration shown in FIG. 4 in that a relief valve that opens when a predetermined pressure or more is used instead of an orifice 4 5 has been established. Here, the relief valve 45 is provided with a through hole 46 separately from the communication passage 31, and a valve element 47 is seated in the through hole 46 from the outlet side passage portion side, and a spring 48 is used. The valve element 47 is constantly urged in a direction to close the through hole 46. The predetermined pressure is a pressure at which a differential pressure between the high pressure, the low pressure, and the spring pressure is balanced. When the high pressure is higher than this pressure, the valve element moves to open the through hole 46. In addition, the relief valve 45 is disposed downstream of the pressure reducing control valve 30 with respect to the inlet-side passage portion 11. Since other configurations are the same as those of the above configuration example, the same portions are denoted by the same reference numerals and description thereof will be omitted.

In such a configuration, since the high pressure is a relief valve 4 5 opens if greater than a predetermined pressure, control the cycle by only reducing pressure adjusting valve 3 0 encapsulating the carbon dioxide (C 0 ₂₎ Compared with the conventional one (shown by the broken line in FIG. 6), the relationship between the refrigerant temperature at the inlet of the expansion device and the refrigerant pressure can be shown by the solid line in FIG. Release in Even if the installed refrigeration cycle starts, it is possible to suppress the high pressure and prevent the ONZ OFF of the compressor due to frequent operation of the high pressure cut switch, preventing deterioration of air conditioning feeling can do.

In addition, the relief valve 45 is provided downstream of the pressure-reducing control valve 30, and when the refrigerant temperature is high, the refrigerant flows from the high-pressure space 13 to the outlet-side passage portion 12 via the relief valve 45. Therefore, the refrigerant radiated by the radiator 3 flows around the pressure reducing control valve 30, and the cooling of the pressure reducing valve 30 can be promoted. Thereafter, when the temperature of the refrigerant passing through the expansion device 5 decreases, the pressure-reducing control valve 30 that has been closed is opened, and it is possible to shift to normal pressure-reducing control. It can be guaranteed.

Furthermore, also in this configuration, since the allowable withstand voltage does not need to be increased, the withstand voltage design value of each component can be reduced, and as a result, each component can be reduced in size and weight, and the vehicle can be rapidly mounted. In the case where the high-pressure side pressure suddenly rises due to an increase in the number of revolutions of the compressor, such as in the case of acceleration, it is possible to cope with the above-described configuration example. Although it differs from the case of the orifice in that the valve is not opened until the pressure reaches a predetermined value, it is sufficiently possible to provide the same function as the orifice by adjusting the valve opening pressure and the diameter of the through hole 46. Yes, it can be a configuration that can suppress intermittent cycle fluctuations.

The configuration of the expansion device 5 shown in FIGS. 4 and 5 shows an example of a pressure reducing control valve using a diaphragm, but as shown in FIGS. 7 and 8, the temperature of the high-pressure side refrigerant is reduced. Alternatively, a pressure-reducing control valve 50 using a bellows 51 whose opening is controlled by pressure and pressure (refrigerant condition) may be used instead. According to such an expansion device, the gas sealed in the bellows senses the refrigerant temperature on the high pressure side. As a result, the volume inside the bellows is increased or decreased, and the bellows 51 expands and contracts also due to the high-pressure side refrigerant pressure, so that the bellows 51 is lowered according to the relationship between the high-pressure side refrigerant temperature and the refrigerant pressure. The position of the valve element 34 connected via the valve 35, that is, the valve opening, is adjusted. By adjusting the amount and type of gas sealed in the bellows, The relationship between the refrigerant temperature and the refrigerant pressure is set so as to have predetermined optimum characteristics, so that the same operation and effect as those of the expansion device using the diaphragm can be obtained.

The diameter of the orifice 43 is preferably set in a range of 0.3 mm to 1.5 mm. It uses a C 0 variable displacement compressor in _two cycles, and, when the high pressure of this cycle is assumed as operating at a low load condition to be subcritical region, valve body as the expansion device described above However, even if the valve body is seated on the valve seat and the refrigerant can be supplied to the low pressure side, such a phenomenon can be avoided. It is necessary to secure at least the size required to supply the refrigerant to the low-pressure side. That is, if the diameter of the orifice 43 is reduced as much as possible, such an effect cannot be expected, so that the lower limit of the orifice diameter is naturally set. Further, according to the study of the present inventors, it is necessary to prevent the orifice 43 from being clogged by oil or the like mixed in the refrigerant while obtaining the effect of avoiding the above-described phenomenon. As a result of repeated studies taking these factors into account, the conclusion was reached that the diameter of the orifice 43 must be at least 0.3 mm.

In addition, it is desirable that the diameter of the orifice 43 should be large enough to obtain a high pressure at which subcooling can occur in consideration of the efficiency of the refrigeration cycle (heat absorption or coefficient of performance). 3 diameter As a result of experimentally measuring the diameter at which the subcool begins to emerge with a gradual reduction, the subcool begins to emerge (the characteristic line of the subcool begins to rise) as shown in Fig. 9. The diameter of the orifice 43 is 1.5 mm, it was concluded that it would be preferable to use this as the upper limit and make the diameter smaller than this. From the above, it was eventually found that it is preferable to set the diameter of the orifice 43 in the range of 0.3 mm to 1.5 mm.

10 and 11 show that the valve means 34 as the leak means of the expansion device can minimize the communication state of the communication passage 31 instead of the orifice 43 (in this example, (Even in the state where the valve element 34 is seated on the valve seat 33) An example is shown in which a path through which a small amount of refrigerant flows from the high pressure side to the low pressure side is formed. Of these, the configuration shown in FIG. A groove 55 is formed from the high-pressure space 13 to the communication passage 31 so as to cross the part of the spherical valve element 34 that comes into contact with the valve seat 33. In this example, the groove is formed so as to reduce the diameter of the central portion of the valve body. In the configuration shown in FIG. 11, a groove 56 is formed in the valve seat 33 from the high-pressure space 13 to the communication passage 31. These grooves 55 and 56 have a passage approximately the same as the passage cross section of the orifice having a diameter of 0.3 mm to 1.5 mm when the valve element 34 is seated on the valve seat 33. It is preferable to form so that a cross section (groove cross section) can be obtained.

In this configuration, the same operation and effect as the case where the orifice is provided can be obtained. In addition, the configuration is useful particularly when there is not enough room for forming the orifice near the valve seat.

By the way, the shape of the valve body may be spherical as described above, but as shown in FIGS. 12 (a) and (b), it has been found that it is more preferable to form the valve body into a needle shape. I have. This is when the valve body is spherical The change in the opening area of the communication passage with respect to the change in the valve lift is large, so that even a small lift of the valve makes it easy for the refrigerant to flow at a stretch, and if the valve lift is not carefully adjusted, large pressure fluctuations will occur. This is because it is easy to induce

For this reason, by changing the valve shape from a spherical shape to a needle shape, the change in the effective opening area of the communication passage 31 is reduced, especially in the initial stage of the lift, and even when the expansion valve is opened, the refrigerant on the high pressure side flows into the low pressure side at a stretch. Can be eliminated.

The needle-shaped valve element 60 used in this example has a frusto-conical shape as shown in FIG. 12 and crosses a portion in contact with the valve seat 33 on the conical surface. A groove 61 is formed from the high-pressure space 13 to the communication passage 31 at the bottom. Particularly, in this example, by providing the groove 61 at three places around the valve body 60, the leak means is formed. Are configured.

The total cross-sectional area of the passage formed between the valve body 60 and the valve seat 33 in a state where the valve body 60 is seated on the valve seat 33, that is, the total of the groove cross sections is 0.3 mm to 1.5 mm in diameter. The passage cross section may be substantially the same as the passage cross section of the orifice having a diameter within the range of, more preferably, the area of the hole having a diameter of about 0.3 to 0.5 mm (0.07 to 0. 20 mm ² ) has been found to be most effective when set to the same level.

Instead of forming a groove in the valve body 60, a groove 62 is formed on the valve seat 33 side from the high-pressure space 13 to the communication passage 31 as shown in FIG. Further, an orifice 63 may be formed beside the valve seat 33, as shown by a broken line in FIG. Particularly, in this example, the groove 62 on the valve seat side is realized by forming a groove on the inner surface of the communication passage 31 in the axial direction of the passage. Such a groove on the valve seat side Also in the case of the valve body 62 and the orifice 63, when the valve body 60 is seated on the valve seat 33, the diameter as a whole is 0.3 π between the inlet side passage portion 11 and the outlet side passage portion 12. ! More preferably, the area of the hole having a diameter of about 0.3 to 0.5 mm (0.07 to 0.20 mm) is obtained so as to obtain a passage cross section equivalent to the area of the hole of about 1.5 mm. It is formed so that the same cross section as ² ) can be obtained.

By using such a needle-shaped valve element, the rate of increase in the opening area can be reduced at the initial stage of the valve element lifting, so that a large amount of refrigerant flows into the low-pressure line at the initial stage of the valve element lifting. Can be prevented, and pressure fluctuation can be suppressed as compared with the case where a spherical valve element is used, and a large fluctuation of the blown air temperature can be reduced.

Actually, when the above-described needle-shaped valve element was used to examine a cycle state when a leak portion having a cross-sectional area approximately equal to the area of a hole having a diameter of about 0.4 mm was examined, As shown in Fig. 17, hunting was eliminated, and it was recognized that there was no change in the temperature of the refrigerant at the outlet side of the evaporator 6, and as a result, the change in the outlet air temperature due to hunting was reduced by 3 °. C can be suppressed to around.

FIGS. 14 and 15 show another configuration example of the leak means. In this example, the valve body 65 is not provided with a valve seat and is not seated, but a spool shape which enters the communication hole 31. A leak means for leaking refrigerant from the inlet side passage portion 11 to the outlet side passage portion 12 (the high pressure space 13 to the communication passage 31) in a state where the communication state of the communication passage 31 is minimized, It is characterized in that a predetermined gap (clearance) 66 is provided between the valve body 65 and the communication path 31 in a state where the valve body 65 is inserted into the communication path 31. is there.

Also in this example, the insertion end of the valve body 65 inserted into the communication hole 31 is circular. The valve is shaped like a frustum to reduce the rate of increase in the opening area of the valve body 65 with respect to the lift, and to prevent a large amount of refrigerant from flowing into the low-pressure line at the beginning of the valve body lift. I have. The clearance (clearance) 66 between the valve body 65 and the communication passage 31 formed when the valve body 65 is inserted into the communication passage has a diameter of 0.3 mm to l as a whole. More preferably, the same area as a hole having a diameter of 0.3 to 0.5 mm (0.07 to 0.20 mm ² ) is used so that a passage cross section equivalent to the area of a hole of 0.5 mm is obtained. It is desirable to adjust so that a passage cross section of a certain degree can be obtained.

Even in such a configuration, as in the case of using the needle-shaped valve element shown in FIG. 12, by increasing the rate of increase in the opening area of the valve element with respect to the lift, a large amount of refrigerant is generated at the beginning of the valve element lift. In this way, it is possible to prevent the air from flowing into the low-pressure line, suppress large pressure fluctuations, and reduce large fluctuations in the outlet air temperature. Industrial applicability

As described above, according to the present invention, in a refrigeration cycle using a refrigerant having a low critical point as a refrigerant, that is, a refrigerant that can be used in a supercritical region such as carbon dioxide (co ₂ ), an inlet to an expansion device is provided. First and second valve bodies for changing the communication between the side passage portion and the outlet side passage portion are provided, and the first valve body is controlled by a first sensing element in which carbon dioxide gas is sealed. However, since the second valve element is controlled by the second sensing element in which an inert gas is sealed, the inert gas is used at the start of the cycle by using the sensing elements having two different characteristics. The enclosed second sensing element works to flow the refrigerant cooled by the radiator to the expansion device to control the pressure, and after the refrigerant temperature decreases, the first sensing element containing the carbon dioxide gas is activated. Can work and perform normal control, It is possible to ensure the start-up operation of a cycle Wear.

In addition, even when the rotation speed of the compressor increases during rapid acceleration and the high-pressure side pressure increases rapidly, the second sensing element filled with the inert gas works so that the refrigerant can flow to the low-pressure side. Frequent operation of the high-pressure switch can prevent the compressor from being frequently turned off and the air conditioning feeling will not be impaired.

Furthermore, because the inflator is constructed by integrating the two sensing elements, there is no burden on the installation space of the cycle, etc., and a sensing element filled with carbon dioxide and a sensing element filled with inert gas are used. By integrating the two in the expansion device, the operation of the two valve bodies can be smoothly connected.

In addition to the configuration in which the communication state is controlled by a valve element controlled by a sensing element filled with gas, the inlet side passage when the valve element is seated on a valve seat is connected to the expansion device of the refrigeration cycle using supercritical refrigerant as the refrigerant. If a configuration is provided in which a leak means is provided to allow the refrigerant to leak from the section to the outlet side passage section, the refrigerant can flow from the inlet side passage section to the outlet side passage section via the leak means even at the start of a cycle where the refrigerant temperature is high. In addition to accelerating the cooling of the expansion device, after the refrigerant temperature has dropped, the gas-filled sensing element works to shift to normal pressure reduction control, ensuring a smooth cycle start operation. be able to.

Even in such a configuration, an abnormal increase in the high pressure at the start of the cycle can be suppressed, so that the withstand voltage design value of each component can be reduced, and each component can be reduced in size and weight.

In addition, the provision of the leak means makes it possible to supply the refrigerant to the low-pressure side by the leak means even when the expansion device is closed during a steady operation at a low load, thereby suppressing a decrease in the low-pressure pressure. Inconvenience of reduced compressor displacement Can be avoided and the pressure on the inflow side of the inflator can be increased at an early stage, promptly opening the inflator, and the inconvenience of large intermittent cycle fluctuations can also be suppressed. .

The leak means for leaking the refrigerant from the inlet side passage portion to the outlet side passage portion in a state where the communication state of the communication passage is minimized by the valve body is an orifice formed between the inlet side passage portion and the outlet side passage portion. Even if it is configured by providing a predetermined gap (clearance) between the valve element and the communication path, the groove formed in the valve element and the valve seat formed on the valve element seat the valve element. The diameter may be 0.3 mm to 1.5 mm when the leak means is constituted by an orifice, or by a gap (clearance) or a groove. It is preferable that the diameter of the orifice is set so as to have a passage cross-sectional area of about 0.3 to 0.5 mm. Clearance) If grooves are formed, cycle fluctuations can be effectively avoided and clogging of the orifice can be prevented. Also, if the leak means is composed of a relief valve, the refrigerant can flow from the inlet-side passage to the outlet-side passage through the relief valve even at the start of the cycle when the refrigerant temperature is high, thus cooling the expansion device. After the refrigerant temperature drops, the sensing element filled with gas works to shift to normal depressurization control, which also helps to ensure smooth cycle start operation. .

Claims

The scope of the claims

1. A compressor that compresses the refrigerant to make the refrigerant in a high-pressure line in a supercritical state depending on operating conditions, a radiator that cools the refrigerant compressed by the compressor, and depressurizes the refrigerant cooled by the radiator. In a refrigeration cycle configured at least by an expansion device and an evaporator that evaporates the refrigerant decompressed by the expansion device,

The inflation device,

An inlet-side passage communicating with the radiator,

An outlet-side passage portion communicating with the evaporator side;

First and second valve bodies provided between the inlet-side passage portion and the outlet-side passage portion to change a communication state between the inlet-side passage portion and the outlet-side passage portion;

A first sensing element for sensing a refrigerant condition on the radiator side with carbon dioxide gas sealed therein and controlling a movement of the first valve element according to the refrigerant condition on the radiator side;

A second sensing element for sensing the refrigerant pressure on the radiator side with an inert gas sealed therein and controlling the movement of the second valve element according to the refrigerant pressure on the radiator side;

A refrigeration cycle comprising:

2. A compressor that compresses the refrigerant to make the refrigerant in the high pressure line in a supercritical state depending on operating conditions, a radiator that cools the refrigerant compressed by the compressor, and depressurizes the refrigerant that is cooled by the radiator. In a refrigeration cycle configured at least by an expansion device and an evaporator that evaporates the refrigerant decompressed by the expansion device,

The inflation device, An inlet-side passage communicating with the radiator,

An outlet-side passage portion communicating with the evaporator side;

A valve body that changes a communication state of a communication path formed between the inlet-side passage portion and the outlet-side passage portion;

A gas is sealed inside to sense a refrigerant condition on the radiator side, and a sensing element for controlling the movement of the valve element according to the refrigerant condition on the radiator side; and a communication state of the communication passage by the valve element. A leak means for leaking refrigerant from the entry side passage to the exit side passage in a state where

A refrigeration cycle comprising:

3. The refrigeration cycle according to claim 2, wherein the leak means is an orifice formed between the inlet-side passage and the outlet-side passage apart from the communication passage.

4. The refrigeration cycle according to claim 3, wherein the orifice has a diameter set between 0.3 mm and 1.5 mm.

5. The refrigeration cycle according to claim 2, wherein the leak means is configured by providing a gap between the valve body and the communication passage.

6. About 0 to total cross-sectional area of the gap. 0 7 to 0.2 0 refrigerating cycle according to claim 5, wherein the set to mm ^2.

7. The refrigeration cycle according to claim 2, wherein the leak means is constituted by a groove formed in the valve body.

8. The refrigeration cycle according to claim 2, wherein the leak means is constituted by a groove formed in a valve seat on which the valve body is seated.

9. The total cross-sectional area of the portion where the coolant leaks from the inlet side passage portion to the outlet side passage portion by the groove is set to about 0.07 to 0.20 mm ² . 9. The refrigeration cycle according to claim 7, wherein:

10. In place of the orifice, another communication passage communicating between the inlet-side passage and the outlet-side passage is provided separately from the communication passage, and the other communication passage is provided with the inlet-side passage. 4. The refrigeration cycle according to claim 3, further comprising a relief valve that opens when the pressure of the refrigeration system exceeds a predetermined pressure.

11. The refrigeration cycle according to claim 5, wherein the valve element has a spool shape that moves in the communication passage.

12. The refrigeration cycle according to claim 7, wherein the valve element has a needle shape.

13. The refrigeration cycle according to claim 1, wherein the refrigerant is carbon dioxide.