JP2001116400A - Refrigeration cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle employing refrigerant having a low critical point such as carbon dioxide CO2, in which stabilized cooling capacity is attained by improving an expansion unit to retard occurrence of intermittent cycle variation under low load regardless of the thermal load. SOLUTION: The expansion unit 5 in a refrigeration cycle is provided with a plurality of pressure reduction regulating valves 16, 17 for varying the conducting state between a high pressure side space 11 and a low pressure side space 12 and the opening characteristics is differentiated for the refrigerant pressure in the high pressure side space 11 by means of the pressure reduction regulating valves 16, 17. The opening characteristics may be differentiated by differentiating the kind or quantity of encapsulated fluid, the variation of valve opening per unit stroke, the force of a spring for urging valve discs 19, 22 in the closing direction or the pressure receiving area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

THE INVENTION Field of the Invention The present invention, refrigerant low critical point as the refrigerant, for example, relates to a refrigeration cycle using a refrigerant that can be used in supercritical region as such carbon dioxide (CO _2).

[0002]

_2. Description of the Related Art As a refrigerating cycle using carbon dioxide (CO ₂ ) as a refrigerant, a configuration disclosed in Japanese Patent Application Laid-Open No. 9-264622 is known. This is to control the outlet pressure of the radiator by a pressure control valve, the pressure control valve is formed in the refrigerant flow path, and a partition part that partitions the refrigerant flow path into an upstream space and a downstream space. A valve port formed in the partition wall for communicating the upstream space and the downstream space, and a displacement that forms a sealed space in the upstream space and is displaced according to a pressure difference between the inside and outside of the sealed space. A member and a valve body for opening and closing the valve port, wherein 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, and the valve body is The valve port is opened when the displacement member is displaced.

According to such a pressure control valve, when the pressure on the outlet side of the radiator is increased, the displacement member is displaced by the pressure difference between the pressure of the refrigerant sealed in the closed space and the valve body. The part is moved in the direction to open the valve port, so that 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 expands so that the displacement member Displaces and moves the valve body in the direction to close the valve port, so the outlet pressure of the radiator rises and the outlet pressure of the radiator can be increased without increasing the compression work of the compressor. Therefore, the cooling capacity can be secured while suppressing the deterioration of the coefficient of performance of the refrigeration cycle.

[0004]

[SUMMARY OF THE INVENTION However, in a refrigeration cycle using a low critical point refrigerant as described above in the CO _2, the pressure in the high pressure line while the compressor variable capacity is lower than the critical pressure nitrous When operating at low load in the critical region, the refrigeration cycle is intermittent even during steady-state operation where the discharge rate of the compressor and the load on the radiator and condenser are constant (environmental conditions are constant). A phenomenon that causes large fluctuations has been confirmed.

Various causes have been estimated as the cause of such a phenomenon, but the main causes are considered as follows. That is, regardless of the diaphragm type expansion device or the bellows type expansion device, the gas sealed in the expansion device expands or contracts in accordance with the refrigerant temperature on the inflow side of the expansion device, and the position of the valve element is increased. Is displaced, and the position of the valve body is displaced according to the refrigerant pressure on the inflow side of the expansion device. Therefore, the sealing gas is sealed so that the relationship between the refrigerant temperature and the refrigerant pressure has optimal control characteristics. The opening degree of the expansion device is adjusted to a target opening degree in accordance with the refrigerant temperature and the refrigerant pressure on the inflow side.

However, when a variable displacement compressor is used at a low load, the amount of discharge is originally small, and the pressure in the high pressure line is relatively low, so that the expansion device attempts to close. Work in the direction. In particular,
At such a low load, if the opening degree of the expansion device is stable at a position where the optimum refrigerant pressure P is obtained for a certain refrigerant temperature T, the refrigerant temperature may become T
If it is relatively higher than this, the expansion device will be closed at low load because the opening degree is initially small.

[0007] Then, the refrigerant supplied to the low-pressure line via the expansion device disappears. In the variable displacement compressor, the discharge amount is controlled according to the low pressure, and the discharge amount is reduced if the low pressure is low, and the discharge amount is increased if the low pressure is high. From that
When the amount of the refrigerant supplied to the low-pressure line decreases, the discharge amount of the compressor also decreases. When the discharge rate of the compressor is reduced, the operation of reducing the specific volume of the refrigerant by the condensing action of the radiator at low load where the cycle operates in the subcritical region is smaller than the operation of supplying the refrigerant and increasing the volume Therefore, the refrigerant pressure on the high pressure side does not rise for a while, and the closed state of the expansion device is maintained.

[0008] Even in such a state, the compressor continues to discharge the refrigerant little by little to the high pressure side.
As the condensation in the radiator progresses, the area of the radiator that actually releases the heat gradually decreases, so the refrigerant discharged from the compressor is more effective than reducing the specific volume of the refrigerant by the condensation of the radiator. Thus, the operation of increasing the volume is superior, and the high pressure gradually increases. Then, when the high pressure required to open the valve is reached, the expansion device opens and the refrigerant on the high pressure side flows at a stretch to the low pressure side, and the flow of the refrigerant suddenly flows into a cycle where the flow of the refrigerant has almost stagnated until now. Occurs. Then, it is considered that a cycle fluctuates greatly intermittently by repeating such a series of operations thereafter.

In particular, in the conventional expansion device, since the throttle is adjusted by one valve, the expansion device is opened mainly at a position where the heat load is high (based on the case where the refrigerant pressure in the high pressure line exceeds the critical pressure). When the valve characteristics are set, the opening degree of the expansion device is originally small at low load (when the refrigerant pressure in the high pressure line is lower than the critical pressure). If the pressure is almost constant irrespective of the load, the valve will be closed by a slight pressure fluctuation. That is, when the load is low, the movement of the valve body becomes too sensitive to the pressure fluctuation, so that the above-described phenomenon is further caused.

Therefore, according to the present invention, in a refrigeration cycle using a refrigerant having a low critical point, such as carbon dioxide (CO ₂ ), by improving an expansion device, a low-temperature refrigerant which can be generated intermittently regardless of a heat load. It is an object of the present invention to provide a refrigeration cycle that makes it difficult for cycle fluctuations to occur at the time of load and that can obtain a stable cooling capacity.

[0011]

In order to achieve the above object, a refrigeration cycle according to the present invention comprises: a compressor for compressing a refrigerant to set a high pressure line in a supercritical state depending on operating conditions;
A refrigeration system comprising at least a radiator for cooling the refrigerant compressed by the compressor, an expansion device for decompressing the refrigerant cooled by the radiator, and an evaporator for evaporating the refrigerant decompressed by the expansion device. In the cycle, the expansion device includes a high-pressure space communicating with the radiator side, a low-pressure space communicating with the evaporator side, and a plurality of valve bodies that change a communication state between the high-pressure space and the low-pressure space. Responsive to the refrigerant condition on the radiator side, and having a sensing element corresponding to each valve element for controlling the movement of each valve element according to the refrigerant condition on the radiator side, the refrigerant pressure in the high-pressure space The opening degree characteristics for the pressure-reducing control valve constituted by the valve element and the corresponding sensing element are made different from each other (claim 1).

Therefore, even if one pressure reducing valve is closed at a low load, the opening characteristics of the other pressure reducing valves are different. Since the state can be avoided and the refrigerant can be supplied to the evaporator side, it is possible to suppress an extreme decrease in pressure in the low pressure line and an extreme decrease in the discharge amount of the compressor.

As means for making the opening degree characteristics of the pressure reducing control valve with respect to the refrigerant pressure in the high pressure space different between the pressure reducing valves, a fluid other than the inert gas is sealed in each pressure reducing valve, and each pressure reducing valve is filled with the fluid. It can be dealt with by changing the type and amount of the enclosed fluid (claim 2,
3) Even if the amount of change in the valve opening per unit stroke of each pressure reducing control valve is made different (claim 4), a spring for urging the valve body in the valve closing direction is provided to each pressure reducing valve. Even if provided, the biasing force of the spring biased to each valve element is made different (claim 5), but the pressure receiving area for receiving the refrigerant pressure in the high pressure space in the sensing element of each pressure reducing control valve is made different. (Claim 6).

In particular, if the opening characteristics of the high-pressure space with respect to the refrigerant pressure are made different by the two pressure-reducing control valves, the following may be performed. That is, the first and second valve bodies for changing the communication state between the high-pressure space and the low-pressure space are provided, and are responsive to the refrigerant condition on the radiator side. A first pressure-reducing control valve having a first sensing element for controlling the movement of the valve body, and sensing the refrigerant condition on the radiator side, and the movement of the second valve body according to the refrigerant condition on the radiator side And a second pressure-reducing control valve having a second sensing element for controlling the pressure-reducing valve. Set to a characteristic that does not change and increases above a predetermined pressure,
Until the change in the valve opening with respect to the change in the refrigerant pressure in the high-pressure space reaches the predetermined pressure, the second pressure-reducing control valve is increased at a smaller rate than the rate at which the opening of the first pressure-reducing control valve changes at or above the predetermined pressure. At the same time, it is preferable to set the characteristic so that it hardly changes at a predetermined pressure or higher.

With this configuration, the opening characteristics of the expansion device as a whole are different from the opening characteristics of the first pressure reducing control valve and the second opening characteristics.
Therefore, when the refrigerant pressure in the high-pressure space is low, the change in the opening degree with respect to the fluctuation in the refrigerant pressure in the high-pressure space is smaller than when the refrigerant pressure in the high-pressure space is high. That is, since the fluctuation of the opening degree of the expansion device can be made slower as the high pressure is lower, even when the refrigeration cycle is operated in a low load region, the risk of the expansion device becoming blocked can be reduced, For this reason, a remarkable decrease in low pressure and a remarkable decrease in the discharge amount of the compressor can be suppressed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a refrigeration cycle 1
Is a compressor 2 for compressing the refrigerant, a radiator 3 for cooling the refrigerant, an internal heat exchanger 4 for exchanging heat between the high-pressure line and the low-pressure line, an expansion device 5 for depressurizing the refrigerant, and evaporating the refrigerant. The apparatus has an accumulator 7 for separating the refrigerant flowing out of the evaporator 6 into gas and liquid. In this cycle, the discharge side (D) of the compressor 2 is connected to the high pressure passage 4a of the internal heat exchanger 4 via the radiator 3, and the outlet side of the high pressure passage 4a is connected to the expansion device 5, The path from the discharge side of No. 2 to the expansion device 5 is a high-pressure line 8. The outlet side of the expansion device 5 is connected to an evaporator 6, and the outlet side of the evaporator 6 is connected to a low-pressure passage 4 b of the internal heat exchanger 4 via an accumulator 7. The outflow side of the low-pressure passage 4b is connected to the suction side (S) of the compressor 2.
And a path from the outflow side of the expansion device 5 to the compressor 2 is a low-pressure line 9.

In the refrigeration cycle 1, CO ₂ is used as a refrigerant, and the refrigerant compressed by the compressor 2 enters the radiator 3 as a high-temperature and high-pressure supercritical refrigerant, and radiates heat there. Cooling. Then, the internal heat exchanger 4
Is cooled further by heat exchange with the low-temperature refrigerant flowing out of the evaporator 6 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 become gaseous. It is heated by heat exchange and returned to the compressor 2.

As shown in FIG. 2, the expansion device 5 includes a high-pressure space 11 communicating with the high-pressure passage 4a of the internal heat exchanger 4 in the housing 10 (communicating with the radiator side), and an evaporator 6.
And a low-pressure space 12 communicating with the high-pressure space 11 and the low-pressure space 12.
The first and second communication passages 14 and 15 are connected to each other.

In the high-pressure space 12, first and second pressure-reducing control valves 16 and 17 are accommodated.
A valve body 19 seated on a valve seat 18 formed in an opening portion of the first communication passage 14 opening into the high-pressure space 11;
9 and a first bellows 20 which moves integrally. The first bellows 20 is filled with a first sealed fluid. Similarly to the first pressure-reducing control valve 16, the second pressure-reducing control valve 17 includes a valve body 22 that is seated on a valve seat 21 formed at an opening portion of the second communication passage 15 that opens into the high-pressure space 11. A second bellows 23 joined to the valve body 22 and moving integrally therewith, and a second sealed fluid is sealed in the second bellows 23.

In this example, the same valve element and bellows are used for each pressure reducing control valve. However, each of the pressure reducing valves 16 and 17 controls the refrigerant pressure in the high pressure space 11 and the refrigerant temperature around the bellows. The opening pressures of the pressure-reducing control valves 16 and 17 and the movements of the valve bodies 19 and 22 are adjusted by changing the type of fluid to be sealed in the bellows. Communication path 1 indicated by the refrigerant pressure of 11 and the substantial opening area of communication paths 14 and 15
The opening degree characteristics of Nos. 4 and 15 are set as shown in FIG.

That is, as shown by α in FIG. 3, the opening degree characteristic of the first pressure reducing control valve alone is determined by changing the opening degree of the communication path represented by the substantial opening area of the first communication path 14 to the high pressure pressure. It is set so as to obtain such a characteristic that it is hardly increased at a low temperature and increases rapidly at a certain pressure (Px) or more.
In other words, the first pressure-reducing control valve 16 is set to be very small until the variation of the valve opening with respect to the variation of the refrigerant pressure in the high-pressure space 11 reaches the predetermined pressure (Px).
x) The values are set to be larger in the above.

On the other hand, as shown by β in FIG. 3, the opening degree characteristic of the second pressure reducing control valve
The opening degree of the communication path indicated by the substantial opening area of 5 is set to be such that the opening degree is increased from a low high-pressure pressure and a fully opened state is obtained at a certain pressure (Px) or more.
In other words, the second pressure-reducing control valve 17 is kept at a pressure equal to or higher than the predetermined pressure (Px) of the first pressure-reducing control valve 16 until the fluctuation of the valve opening with respect to the fluctuation of the refrigerant pressure in the high-pressure space 11 becomes the predetermined pressure (Px). Are set so as to increase at a rate smaller than the rate of change and hardly change above a predetermined pressure (Px).

Here, as the first sealed fluid and the second sealed fluid, different types of fluids except for an inert gas are used, and are used in a supercritical region having a low critical point such as carbon dioxide gas. A gas that can be used, or a mixed gas of carbon dioxide and another gas, a liquid, or the like may be used. In addition, γ in FIG. 3 is the opening characteristic when the expansion device 5 is viewed as a whole, that is, α and β.
Are added.

When a control line of the expansion device having such characteristics is viewed on a Mollier diagram of a refrigeration cycle using carbon dioxide as a refrigerant, as shown in FIG. 4, a control line on the inlet side of the expansion device is shown. (Characteristic line obtained by plotting the high pressure obtained with respect to the refrigerant temperature at the inlet of the expansion device) is set as shown by a broken line in the drawing if the first pressure reducing control valve is a single unit, and the second pressure reduction is performed. If the control valve is a single unit, it is set as shown by the thin line in the figure. As shown by the thick line in the figure, the second expansion unit shown by the thin line below the critical pressure
Is controlled in accordance with the control line of the first pressure-reducing control valve, and when the pressure is equal to or higher than the critical pressure, the control is performed in accordance with the control line of the first pressure-reducing control valve indicated by a broken line.

In the above construction, when the refrigerant pressure in the high-pressure space 11 is low, the opening degree of all the communication passages with respect to the change in the high-pressure pressure, that is, the change in the opening degree of the high-pressure space, that is, The change in the substantial opening area of all the communication paths becomes small, and becomes large when the refrigerant pressure in the high-pressure space 11 is high. In other words, when the high pressure is low, the fluctuation of the opening degree can be reduced. Therefore, a variable displacement type whose capacity is controlled by the pressure of the low pressure line 9 is used as the compressor 2, and this cycle is performed at a high pressure. Even in the case of operating in a low-load region where the pressure is lower than or equal to the critical pressure, the risk of the expansion device 5 being blocked can be reduced. A remarkable decrease in the discharge amount of the compressor 2 can be suppressed, and a phenomenon in which the refrigeration cycle 1 causes intermittent large fluctuation can be suppressed, and the cooling capacity can be stabilized even at a low load.

This mechanism will be described with reference to a characteristic diagram shown in FIG. 4. When the high pressure is low, it is controlled by the control line of the second pressure reducing valve 17, so that the high pressure becomes a subcritical state. At the time of load, looking at an isotherm at a certain temperature T, the refrigerant pressure of the high-pressure line 8 is set to P1 at the first pressure reduction control valve 16 with respect to this temperature T. Of the pressure reducing control valve of P
2 (P1> P2). For this reason, if the control is performed only by the first pressure reducing control valve 16 as in the related art, the high pressure is controlled to be P1 when the refrigerant temperature is T in the subcritical region. Is closed and intermittent cycle fluctuations occur, but the second pressure reducing control valve 17 arranged in parallel attempts to control the high pressure to P2 lower than P1 when the same T is set. Therefore, at the time P1 when the first pressure reducing control valve 16 is closed, the first pressure reducing valve 16 is opened to further reduce the high pressure. In other words, even when the first pressure-reducing control valve 16 is closed, the refrigerant can flow from the high-pressure line to the low-pressure line via the second pressure-reducing valve 17. It is possible to suppress an extreme decrease in the discharge amount of the refrigeration cycle, and to avoid a phenomenon in which the refrigeration cycle 1 causes intermittent large fluctuations.
The cooling capacity can be stabilized even at a low load when the high pressure is in a subcritical state.

In the above configuration, the type of the fluid to be sealed is made different between the first pressure-reducing control valve 16 and the second pressure-reducing control valve 17, so that the opening degree characteristic of the high-pressure space 11 with respect to the refrigerant pressure is shown in FIG. .Alpha. And .beta., But the characteristics of .alpha. And .beta. In FIG. 3 may be obtained by varying the amount of fluid to be sealed.

By changing the amount of change in the valve opening per unit stroke of each of the pressure-reducing control valves 16 and 17, the opening characteristics of the high-pressure space with respect to the refrigerant pressure are obtained as α and β in FIG. It may be. For example, as shown in FIG. 5, the pressure-reducing control valves 16 and 17 have different valve body shapes to obtain the characteristics of α and β in FIG. 3, for example, the first pressure-reducing control valve 16. The valve body 19 is a needle valve whose diameter continuously changes from its base toward its tip and whose rate of decrease in diameter is gradually increased. As the opening degree of the first communication passage 14 decreases, the pressure increases. The characteristic of α is obtained by reducing the variation of the opening degree with respect to the pressure variation of the space 11, and the second pressure-reducing control valve 16
The valve body may be formed by a ball valve as in FIG. 2 to obtain the characteristic of β.

As means for changing the amount of change of the valve opening per unit stroke of the pressure reducing control valves 16 and 17, the shape of the valve seats 18 and 21 may be changed. The same characteristics can be obtained by appropriately changing and combining the shapes of the valve seats 18 and 21.

A spring 2 for urging the valve bodies 19 and 22 in the first and second bellows 20 and 23 in the valve closing direction.
4 and 25 are provided, and the biasing force of this spring (spring constant)
May be obtained to obtain the characteristics of α and β in FIG. For example, as shown in FIG. 6, the spring constant of the spring 24 housed in the bellows of the first pressure reducing control valve 16 is increased, and the spring 25 housed in the bellows of the second pressure reducing valve 17 is increased. The configuration is such that the spring constant is reduced.

Furthermore, the characteristics of α and β in FIG. 3 can be improved by making the type and amount of the filled fluid the same and making the pressure receiving area for receiving the high-pressure refrigerant in the high-pressure space 11 different between the pressure-reducing control valves 16 and 17. It may be obtained. For example, as shown in FIG. 7, a configuration in which the bellows diameter of the second pressure reduction control valve 17 is larger than the bellows diameter of the first pressure reduction control valve 16 to increase the pressure receiving area of the second pressure reduction control valve 17. Can be considered.

In the above-described configuration, the characteristics shown by the bold line in FIG. 3 can be obtained. Therefore, when the refrigerant pressure in the high-pressure space 11 is low, the expansion degree The change, that is, the change in the substantial opening area becomes small, and becomes large when the refrigerant pressure in the high-pressure space 11 is high. In other words, when the high-pressure is low, the fluctuation of the valve opening can be slowed down. Therefore, a variable displacement type whose capacity is controlled by the pressure of the low-pressure line 9 is used as the compressor 2 and this refrigeration cycle Even in the case of operating in a low-load region where the high-pressure is operated in a subcritical region where the high-pressure pressure is equal to or lower than the critical pressure, it is possible to reduce the risk of the expansion device 5 being blocked. Of the compressor 2 and the discharge amount of the compressor 2 can be suppressed, and the phenomenon that the refrigeration cycle 1 causes intermittent large fluctuation can be suppressed, and the cooling capacity can be stabilized even at a low load. it can.

The various configurations shown above are examples of configurations for obtaining the characteristics shown in FIG. 3, and the types and amounts of the sealed fluid, the shapes of the valve body and the valve seat, the biasing force of the spring, and the like. It is possible to obtain similar characteristics by appropriately changing the pressure receiving area and combining them, and the present invention also covers the configurations not listed in the scope of the present invention. Further, in the above-described configuration, the example in which the bellows is used as the sensing element of the inflation device has been described.However, the configuration holds also in the inflation device using the diaphragm as the sensing element.
Similar functions and effects can be obtained. Furthermore, in the above-described configuration, an example in which two pressure reduction control valves are used has been described. However, even when three or more pressure reduction control valves are used, the opening degree characteristic with respect to the refrigerant pressure in the high-pressure space is controlled by each pressure reduction control valve. It is needless to say that the difference can prevent a state where the opening degree of the expansion device becomes zero at a low load.

[0034]

As described above, according to the present invention,
In a non-electric expansion device, a plurality of valve elements that change a communication state between a high-pressure space and a low-pressure space, and a plurality of sensing elements configured to control the movement of the valve element according to refrigerant conditions on the radiator side. Provide a pressure-reducing control valve to change the type of enclosed fluid, vary the amount of enclosed fluid, vary the amount of valve opening change per unit stroke, and close the valve The opening characteristics of the high-pressure space with respect to the refrigerant pressure are made different for each pressure-reducing valve by changing the urging force of the spring that urges in the direction or by changing the pressure receiving area. By avoiding the inconvenience that the device is easily closed, it is possible to reduce the possibility of intermittently occurring cycle fluctuations at a low load, thereby stabilizing the cooling capacity even at a low load. That is, a stable cooling capacity can be obtained regardless of the heat load.

[Brief description of the drawings]

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 an expansion device of the refrigeration cycle according to FIG. 1;

FIG. 3 is a characteristic diagram showing a change in an opening degree with respect to a pressure in a high-pressure space of an expansion device used in a refrigeration cycle according to the present invention.

FIG. 4 is a Mollier diagram to which control lines of a refrigeration cycle according to the present invention are added.

FIG. 5 is an enlarged cross-sectional view showing another configuration example of the expansion device, and shows an example in which the shape of a valve body is changed.

FIG. 6 is an enlarged cross-sectional view showing still another configuration example of the expansion device, and shows an example in which the biasing force of a spring that biases the valve body in the valve closing direction is made different.

FIG. 7 is an enlarged cross-sectional view showing still another configuration example of the expansion device, showing an example in which the pressure receiving areas are different.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Refrigeration cycle 2 Compressor 3 Radiator 5 Expansion device 6 Evaporator 8 Low-pressure line 9 High-pressure line 11 High-pressure space 12 Low-pressure space 14 First communication path 15 Second communication path 16 First pressure-reducing valve 17 Second Pressure reducing valve 19 First valve body 20 First bellows 22 Second valve body 23 Second bellows 24, 25 Spring

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16K 17/04 F16K 17/04 H (72) Inventor Yuji Kawamura 39 Chiyo-ji, Higashihara, Oji-gun, Osato-gun, Saitama Address: Inside the Xexel Gangnam Plant (72) Inventor Shunji Muta 39, Higashihara, Chiyo-ji, Odai-gun, Osato-gun, Saitama 39 Inventor Kenji Iijima, Kenji Iijima 39, Higashihara, Odai-gun, Osato-gun, Saitama Prefecture Address: Inside the Xexel Gangnam Plant (72) Inventor: Sakae Hayashi 39, Chiyo-ji, Chiyo, Oga-gun, Osato-gun, Saitama 39 Inventor: Hiroshi Kanai (72) Inventor: Hiroshi Kanai, Chiyo-ji, 39: Chiyo, Onan-gun, Osato-gun, Saitama Address: Inside the Xexel Gangnam Plant (72) Inventor: Akihiko Takano 39, Higashihara, Chiyo, Oyo-gun, Osato-gun, Saitama Formula company Zexel Jiangnan plant in the F-term (reference) 3H059 AA07 BB05 CA04 CA12 CB04 CD05 CD12 CE05 EE13 FF05 FF11 FF15

Claims (7)

[Claims] 1. A compressor that compresses a refrigerant to place 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. A refrigerating cycle comprising at least an expansion device and a evaporator for evaporating the refrigerant decompressed by the expansion device, wherein the expansion device has a high-pressure space communicating with the radiator side, and a low-pressure space communicating with the evaporator side. A plurality of valve bodies for changing a communication state between the high-pressure space and the low-pressure space; and a plurality of valves that are responsive to a refrigerant condition on the radiator side, and that each of the valves responds to a refrigerant condition on the radiator side. A sensing element corresponding to each valve body for controlling the movement of the body, and an opening characteristic of the high-pressure space with respect to the refrigerant pressure is reduced by the valve body and the corresponding sensing element. A refrigeration cycle characterized in that it is made different by a control valve. 2. A fluid other than an inert gas is sealed in each pressure-reducing control valve, and the type of fluid sealed in each pressure-reducing control valve is changed to open the high-pressure space with respect to the refrigerant pressure. 2. The refrigeration cycle according to claim 1, wherein the temperature characteristics are different. 3. A fluid other than an inert gas is sealed in each pressure-reducing control valve, and the pressure of the refrigerant in the high-pressure space is increased by varying the amount of fluid sealed in each pressure-reducing control valve. Claim 1 having different degree characteristics
Refrigeration cycle as described. 4. The refrigeration cycle according to claim 1, wherein the degree of opening of the high-pressure space with respect to the refrigerant pressure is varied by varying the amount of change in the valve opening per unit stroke in each pressure-reducing control valve. 5. Each of the pressure-reducing control valves is provided with a spring for biasing the valve body in a valve closing direction, and the biasing force of the spring biased on each valve body is varied to make the valve body have a different biasing force. 2. The refrigeration cycle according to claim 1, wherein the opening degree characteristics of the high-pressure space with respect to the refrigerant pressure are different. 6. An opening characteristic of the high-pressure space with respect to the refrigerant pressure in the high-pressure space by varying the pressure-receiving area for receiving the refrigerant pressure in the high-pressure space. Refrigeration cycle. 7. The plurality of valve bodies include first and second valve bodies that change a communication state between the high-pressure space and the low-pressure space, and are responsive to a refrigerant condition on the radiator side, A first pressure reducing control valve having a first sensing element for controlling the movement of the first valve element according to the refrigerant condition on the radiator side; A second pressure-reducing control valve having a second sensing element for controlling the movement of the second valve body in accordance with the condition of the refrigerant on the container side; The variation of the valve opening degree with respect to the variation of the refrigerant pressure hardly changes until the pressure reaches a predetermined pressure, and is set to a characteristic that increases at or above the predetermined pressure. Until the variation of the valve opening with respect to the variation of the refrigerant pressure reaches the predetermined pressure, the first pressure reducing control valve The refrigeration cycle according to claim 1, wherein the opening degree is set to a characteristic that increases at a rate smaller than the rate at which the opening changes at or above the predetermined pressure and hardly changes at or above the predetermined pressure.