JPH06331224A - Refrigerating cycle device - Google Patents

Abstract

PURPOSE:To improve the refrigerating capability of a refrigerating cycle by applying a most suitable supercooling in response to a cooling load, by a simple constitution. CONSTITUTION:A closed circuit is constituted of a compressor 1, condenser 2, expansion valve 3, evaporator 4 and a refrigerant piping 5 which connects them. A hollow cylindrical shape container 6 is provided on a refrigerant piping (liquid piping) 5a between the condenser 2 and expansion valve 3, and the container 6 is divided into a pressure chamber 8 and refrigerant chamber 9 by a piston 7. A low boiling point mixed refrigerant is filled in the pressure chamber 8, and the refrigerant chamber communicates with the liquid piping 5a, and a refrigerant for the refrigerating cycle is stored in the refrigerant chamber 9. Since the piston 7 is movable, the storage space of the refrigerant chamber 9 changes, and the quantity of the refrigerant which is sealed in the refrigerating cycle is adjusted. By adjusting the quantity of the refrigerant to be sealed by the above mentioned method, a most suitable supercooling, which provided the highest coefficient of performance COP at the exit of the condenser 2 can be applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle apparatus, and is suitable for use in, for example, an air conditioning system for automobiles.

[0002]

2. Description of the Related Art Generally, in a refrigeration cycle, the refrigerating capacity is improved by taking a supercool at the condenser outlet. However, if the supercool is taken too large, the pressure of the high-pressure side refrigerant will increase and the power required for the compressor will also increase. As a result, the heat equivalent of work required for compression will increase, resulting in a decrease in the coefficient of performance COP. Resulting in.

In other words, in order for the refrigeration cycle to exhibit the optimum refrigerating capacity, it is necessary to operate the refrigeration cycle so as to take the optimum supercool with the maximum coefficient of performance COP. Based on this point of view, JP-A-55
The refrigerating apparatus of Japanese Patent No. 134253 has been proposed. In this refrigeration system, the receiver is eliminated, and a large-diameter portion of a predetermined length having the same volume as the receiver is provided inside the condenser. Then, by controlling the proportion of the liquid phase or the gas phase in the large diameter portion, a proper supercool is taken, and by extension, the refrigerating apparatus is operated in a state where the refrigerating capacity can be effectively exhibited.

Further, in the condenser proposed in Japanese Patent Application Laid-Open No. 3-95368, the condenser is provided with a main condenser portion, a gas-liquid separation portion and a supplementary condenser portion, which are located before and after the gas-liquid separation portion. The refrigerant was cooled and condensed in the main condenser section and the auxiliary condenser section. Further, the auxiliary condenser section was provided with a sight glass for visually observing the refrigerant state. And by adjusting the refrigerant charge,
It was devised to obtain an appropriate supercool in the gas-liquid separation section.

[0005]

However, in the conventional refrigeration system described above, not only is the condenser-related configuration complicated, but the supercool is adjusted only by the amount of refrigerant enclosed in the refrigeration cycle. Therefore, it was not possible to adjust the operating condition of the refrigeration cycle, that is, the supercool that follows the cooling load.

The present invention has been made by paying attention to the above-mentioned problems, and its object is to simplify the structure and to take the optimum supercool according to the cooling load to refrigerate the refrigeration cycle. It is to provide a refrigeration cycle control device that improves the capacity.

[0007]

In order to solve the above-mentioned problems, the present invention provides a compressor for compressing and discharging a refrigerant, a condenser for condensing the refrigerant discharged from the compressor, and a condenser. Expansion means for decompressing and expanding the condensed liquid refrigerant,
A refrigeration cycle apparatus comprising: an evaporator that evaporates a refrigerant decompressed by the expansion means; and a refrigerant pipe that connects the compressor, a condenser, an expansion means and an evaporator to form a closed circuit, wherein the condensation And a container provided in the refrigerant pipe between the expansion means, the container is a refrigerant chamber that is in communication with the refrigerant pipe and is filled with the refrigerant of the refrigeration cycle, and the temperature of the refrigerant flowing through the refrigerant pipe. The technical means is adopted, which has a responding member that responds to a change and a piston that moves in a direction in which the volume of the refrigerant chamber is reduced by the responding member when the temperature of the refrigerant flowing through the refrigerant pipe rises.

[0008]

According to the above structure, the refrigerant is compressed by the compressor and becomes a high temperature and high pressure gaseous refrigerant and is sent to the condenser. This gaseous refrigerant is condensed in the condenser by heat exchange with the outside air to become a liquid refrigerant, and flows through the refrigerant pipe between the condenser and the expansion means. Further, the refrigerant pipe is provided with a container having a refrigerant chamber communicating with the refrigerant pipe, and a part of the liquid refrigerant flowing through the refrigerant pipe also flows into the refrigerant chamber and is stored in a fixed amount. At this time, it is as if the refrigerant stored in the refrigerant chamber apparently does not flow in the refrigeration cycle.

When the cooling load increases and the temperature and pressure of the liquid refrigerant flowing through the refrigerant pipe increase, the piston provided in the container moves in the direction of decreasing the volume of the refrigerant chamber. As the volume of the refrigerant chamber decreases, the liquid refrigerant stored in the refrigerant chamber is pushed back into the refrigerant pipe, and the amount of refrigerant circulating in the refrigeration cycle increases. A large amount of supercool at the outlet of the condenser can be obtained by the amount of this circulating refrigerant.

Therefore, the supercool at the condenser outlet can be controlled by moving the piston in the container provided in the refrigerant pipe between the condenser and the expansion means as described above, so that the cooling load can be reduced. Accordingly, it is possible to take a super cool that improves the coefficient of performance COP of the refrigeration cycle.

[0011]

EXAMPLES Examples in which the present invention is applied to a refrigeration cycle of an air conditioner for automobiles will be described below. FIG. 1 is a configuration diagram of a refrigeration cycle according to the first embodiment of the present invention. The refrigeration cycle includes a compressor 1, a condenser 2, an expansion valve 3 that constitutes expansion means, an evaporator 4, a refrigerant pipe 5 that connects them to form a closed circuit, and a container 6.

The compressor 1 receives the driving force of an automobile engine (not shown) to adiabatically compress and discharge the refrigerant. Condenser 2
Is a liquid refrigerant by condensing the high-temperature and high-pressure gaseous refrigerant adiabatically compressed by the compressor 1 by heat exchange with the outside air. The expansion valve 3 adiabatically expands this liquid refrigerant into a low-temperature low-pressure gas-liquid two-phase refrigerant. At this time, the expansion valve 3 controls the refrigerant flow rate by the heat-sensitive cylinder 3a located at the outlet of the evaporator 4 so that the gas refrigerant at the outlet of the evaporator 4 always has a constant superheat. The evaporator 4 vaporizes this gas-liquid two-phase refrigerant by heat exchange with the air sent to the room.

As shown in FIG. 1, the container 6 of the present invention is arranged in a high pressure region between the condenser 2 and the expansion valve 3, and the condenser 2 and the expansion valve 3 are connected as shown in FIG. It is a hollow cylindrical container installed so as to enclose a refrigerant pipe (hereinafter, referred to as a liquid pipe) 5a. This container 6 has an outer diameter of 4
It has a length of 0 mm and an axial length of about 100 mm, and is partitioned into two chambers by a disc-shaped piston 7, one of which is a sealed pressure chamber 8 in which a low boiling point mixed refrigerant is sealed. The other is a refrigerant chamber 9 that communicates with the liquid pipe 5a through a communication portion 13, which serves as a mechanism for the liquid refrigerant in the refrigeration cycle to flow in and out. The communication portion 13 may be opened in the refrigerant chamber 9 by cutting the liquid pipe 5a as shown in FIG. 2, or may be formed in the liquid pipe 5a with a plurality of holes. The piston 7 is provided with O-rings 10 and 11 to keep the two chambers airtight. The piston 7
Is urged by a spring 12 having a predetermined spring constant in a direction in which the volume of the refrigerant chamber 9 increases. The position of the piston 7 is determined by the balance between the force of the spring 12 and the three forces of the pressure of the low boiling point mixed refrigerant and the pressure of the liquid refrigerant flowing through the liquid pipe 5a. For example, when the cooling load increases and the temperature of the liquid refrigerant flowing through the liquid pipe 5a rises, the low boiling point mixed refrigerant in the pressure chamber 8 boils, and the pressure in the pressure chamber 8 rises. Here, when the pressure of the low boiling point mixed refrigerant in the pressure chamber 8 becomes larger than the sum of the pressure of the liquid refrigerant in the refrigerant chamber 9 and the urging force of the spring 12, the piston 7 reduces the volume of the refrigerant chamber 7. Move to. In this way, the piston 7 is configured to move so that the volume of the refrigerant chamber 9 becomes appropriate according to the cooling load. That is, it is configured to control the enclosed amount of the circulating refrigerant in the refrigeration cycle and take an optimum supercool according to the cooling load at the outlet of the condenser 2.

Now, the relationship between the cooling load and the supercool will be described. Fig. 4 shows the rate of increase of the coefficient of performance COP for supercool and refrigeration cycle (supercool = 0
It shows the relationship with the COP increment when the coefficient of performance COP at ° C is "1". As can be seen from this figure, the higher the cooling load, the greater the supercool that is the highest coefficient of performance, and further, there is an optimum supercool that maximizes the coefficient of performance COP at each load. Further, FIG. 5 shows the optimum supercool curve created based on FIG. This optimum supercool curve sets the supercool when the coefficient of performance COP is maximum with respect to the cooling load. Therefore, if the flow rate of the refrigerant is controlled so as to match the optimum supercool curve in this figure, the maximum coefficient of performance COP can always be obtained, and the best refrigerating capacity can be exerted.

Next, the operation of the refrigeration cycle apparatus of this embodiment will be described with reference to the Mollier diagram of FIG. In this embodiment, for example, H is used as the refrigerant of the refrigeration cycle.
FC134a is used, and HFC1 is used as a low boiling point mixed refrigerant.
R12, R14 and the like having a lower boiling point than 34a are used. The liquid refrigerant condensed in the condenser 2 is the liquid pipe 5a.
Flow through, and a part thereof flows into the refrigerant chamber 9 and is stored therein.
The liquid refrigerant stored in the refrigerant chamber 9 is similar to that apparently not circulating in the refrigeration cycle.

Under a certain load condition, when the refrigeration cycle is stable, the pressure P of the low boiling point mixed refrigerant in the pressure chamber 8
The relationship between _M and the pressure P _{H of the} HFC 134a and the force F of the spring is expressed by the following equation, where the sectional area of the piston 7 is A.

[0017]

## EQU1 ## P _M × A = P _H × A + F At this time, the piston 7 is located at a point where the respective forces are balanced so as to satisfy the above equation, and a certain amount of HFC134a is stored in the refrigerant chamber 9. ing. As shown in FIG. 6, the amount of circulating refrigerant enclosed in the refrigeration cycle is determined by the position x of the piston 7 in the container 6, and the position x of the piston 7 is determined by the balance of the three forces P _M , P _H , and F. It is determined. P _M and P _H depend on the cooling load. Therefore, the position x of the piston 7 is determined according to the cooling load,
Since the amount of circulating refrigerant enclosed in the refrigeration cycle can be controlled, optimum supercool can be taken at the outlet of the condenser 2.

For example, when the low pressure is 2 kgf / cm ² G and the high pressure is 12 kgf / cm ² G, the piston 7 in the container 6 causes the refrigerant at the inlet of the evaporator 4 to be in the state at point A in FIG. Controlled by. Further, the refrigerant state at the outlet of the evaporator 4 is controlled to the point A by the expansion valve 3, and the gas refrigerant in the superheated vapor state is changed to a high temperature and high pressure gas refrigerant by the compressor 1 and controlled to the point C. Also, the change in the refrigerant at the expansion valve 3 is an isenthalpic change. The refrigerant state at the outlet of the condenser 2 is point E, and theoretically is supercool = 8 ° C.
Take That is, by controlling the amount of the refrigerant filled in the refrigerating device depending on the position of the piston 7, the refrigerant state at the outlet of the condenser 2 can be controlled to the point where the optimum supercool is obtained.

Next, the case where the temperature and humidity of the outside air rise and the cooling load in the evaporator 4 increases and the load becomes high will be described. When the load becomes high, the evaporation temperature of the refrigerant in the evaporator 4 rises, the low pressure rises, and the pressure and temperature on the high pressure side also rise. Therefore, the liquid pipe 5a
The temperature of the liquid refrigerant flowing therethrough rises, and the temperature of the liquid pipe 5a also rises accordingly. When the temperature of the liquid pipe 5a rises, the low boiling point mixed refrigerant in the pressure chamber 8 that has been in the gas-liquid two-phase state at the time of medium load is boiled by receiving the heat. At this time, the HFC 13 in the liquid pipe 5a and the refrigerant chamber 9
4a is always liquid. Therefore, since the pressure increase of the low boiling point mixed refrigerant is larger than the pressure increase of the HFC134a, the relationship of the above three forces is as follows.

[0020]

## EQU2 ## P _M × A> P _H × A + F, and the piston 7 moves in a direction to reduce the volume of the refrigerant chamber 9. And HFC1 stored in the refrigerant chamber 9
When the storage space of 34a decreases, the amount of the circulating refrigerant filled in the refrigeration cycle increases, which eventually leads to an overfilling cycle and a large amount of supercool at the condenser 2 outlet can be taken.

For example, if the cooling load increases, 2 kgf / cm ²
The low pressure, which was G, became 3 kgf / cm ² G, 12 kgf
/ Cm ² when G is a high pressure pressure became 20 kgf / cm ² G, the temperature rises of the liquid refrigerant flowing through the liquid pipe 5a, increase the pressure to boil the low boiling mixed refrigerant in the pressure chamber 8 Then, the piston 7 moves in a direction to reduce the storage space of the refrigerant chamber 9, and controls the storage space so that the refrigerant at the inlet of the evaporator 4 is in the state of point C in FIG. as a result,
The state of the refrigerant at the outlet of the condenser 2 becomes a point in FIG. 3, and the optimum supercool = 14 ° C. is set to balance. In this way, when the cooling load increases, it is possible to control so as to take the optimum supercool.

On the other hand, the case where the cooling load on the evaporator 4 is reduced and the load is low will be described. When the load is low, the evaporation temperature of the refrigerant in the evaporator 4 decreases, the low pressure decreases, and the high pressure and temperature also decrease. In this way, when the load is low, the temperature of the liquid pipe 5a also drops, so that the low boiling point mixed refrigerant does not boil and the pressure difference between the low boiling point mixed refrigerant pressure P _M and the HFC 134a pressure P _H becomes small. The relationship between the three forces P _M , P _H and F is as follows.

[0023]

Equation 3] Thus _{P M × A <P H ×} A + F, the piston 7 is moved in a direction to increase the volume of the coolant chamber 9, the reservoir space HFC134a increases. Therefore, the amount of the refrigerant enclosed in the refrigeration cycle is reduced, and the supercool is reduced at the outlet of the condenser 2.

For example, at a low load such as a low pressure of 2 kgf / cm ² G and a high pressure of 8 kgf / cm ² G,
Since the temperature of the refrigerant flowing in the liquid pipe 5a is lowered, the pressure of the low boiling point mixed refrigerant in the pressure chamber 8 is lowered, and the position x of the piston 7 is set so that the refrigerant at the inlet of the evaporator 4 becomes the point U in FIG.
To control. As a result, the refrigerant state at the outlet of the condenser 2 is shown in FIG.
It becomes a point in and the optimum supercool = 3 ℃ is taken to balance.

As described above, even when the cooling load becomes small, it is possible to control so as to take the optimum supercool. Therefore, as described above, the refrigeration cycle device of the present invention can take the optimum supercool at the outlet of the condenser 2 so as to obtain the highest coefficient of performance COP according to the change of the cooling load.

Next, as a second embodiment, the liquid pipe 5a
FIG. 7 shows a container 20 having a structure different from that of the above-described first embodiment as a container to be attached to. This container 20 has a pressure chamber 2
Instead of enclosing the low boiling point mixed refrigerant in 1, the shape memory alloy springs 23a to 23e are provided, and the refrigerant chamber 22 is gradually provided.
It has a structure that changes the storage space of. Spring 2
3a to 23e expand and contract at different temperatures. For example, the spring 23a expands and contracts at a low temperature and the spring 23e expands and contracts at a high temperature.

The operation of the second embodiment will be described with reference to the Mollier diagram of FIG. In the steady state A → A → U → E, when the temperature at the point D is between the deformation temperatures of the springs 23a and 23b, the spring 23a is in an expanded state and the spring 23
b to 23e are in a contracted state. As the load increases from this, state D moves to state E. Temperature is spring 23
When the deformation temperature of b reaches the state of ', the spring 23b
Is increased, the storage space of the refrigerant chamber 22 is decreased, the amount of refrigerant enclosed in the refrigerating cycle is increased, and the state becomes'on the optimum supercool curve. If the load further increases, the status
Goes to the state F, and the spring 23c extends at the intermediate point C ′ to reach the state D ”on the optimum supercool curve.

As described above, the container 20 of the second embodiment is
This is a device that gradually corrects the state of the refrigerant at the outlet of the condenser 2 onto the optimum supercool curve. In the second embodiment, the correction is made in five steps, but if the number of springs is further increased, finer adjustment can be performed and the optimum supercool curve can be approximated. As the member that responds to the temperature change of the refrigerant flowing through the liquid pipe 5a, in addition to the above-mentioned low boiling point mixed refrigerant and shape memory alloy, wax whose volume changes according to the temperature change and bimetal whose shape changes May be used.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a refrigeration cycle device of the present invention.

FIG. 2 is a diagram showing a configuration of a container according to the first embodiment of the present invention.

FIG. 3 is a Mollier diagram illustrating the operation of the refrigeration cycle apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between supercool and a coefficient of performance increase rate.

FIG. 5 is a diagram showing a relationship between a cooling load and a super cool.

FIG. 6 is a diagram showing a relationship between a cooling load, a piston position, a refrigerant charging amount, and an optimum supercool.

FIG. 7 is a diagram showing a structure of a container according to a second embodiment of the present invention.

FIG. 8 is a Mollier diagram illustrating the operation of the refrigeration cycle apparatus according to the second embodiment of the present invention.

[Explanation of symbols]

 1 Compressor 2 Condenser 3 Expansion valve 4 Evaporator 5 Refrigerant piping 5a Liquid piping 6 Container 7 Piston

Claims (1)

[Claims] 1. A compressor that compresses and discharges a refrigerant, a condenser that condenses the refrigerant discharged from the compressor, an expansion unit that decompresses and expands the liquid refrigerant condensed by the condenser, and the expansion. A refrigeration cycle apparatus comprising: an evaporator that evaporates a refrigerant decompressed by means; a compressor, a condenser, a refrigerant pipe that forms a closed circuit by connecting an expansion means and an evaporator, and the condenser. A container provided in the refrigerant pipe between the expansion means is provided, wherein the container is in communication with the refrigerant pipe and is filled with a refrigerant of a refrigeration cycle, and a temperature change of the refrigerant flowing through the refrigerant pipe. When the temperature of the refrigerant flowing through the refrigerant pipe rises, the moving member moves in a direction of decreasing the volume of the refrigerant chamber by the reacting member, and when the temperature of the refrigerant decreases, the reacting member causes the temperature to decrease. Refrigerating cycle apparatus characterized by and a piston that moves in a direction to increase the volume of the medium chamber.