KR20060132869A - Refrigerator - Google Patents

Abstract

A refrigerator where a variable- performance freezing cycle that has coolers for freezing and cold storage and is formed as a two-stage compression-type is controlled by freezing space temperature information, so that a freezing space and a cold storage space are each appropriately controlled at its storage temperature. A refrigerator where a freezing cycle is formed by an inverter-driven variable-performance compressor (9) where a compression element is constituted of a low stage side compression section (9a) and a high stage side compression section (9b), by a switching valve (11) for controlling a flow rate together with a refrigerant flow path provided on the exit side of a condenser (10) receiving a discharge gas from the compressor, and by cooler (4) for freezing and a cooler (5) for cold storage that are respectively connected through pressure reducing devices (12, 13) to the switching valve, wherein the rotating speed of the compressor is determined by a freezing space temperature (Fa) and a target value (Fr) for the freezing space temperature.

Description

Refrigerator {REFRIGERATOR}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator using a two stage compression capacity variable compressor, and more particularly, to determining the rotation speed of the compressor based on the storage space temperature.

In recent years, many refrigerators are equipped with a compressor of variable capacity by inverter control, and the refrigeration capacity of the refrigerator is variable, thereby achieving cooling performance corresponding to the load and reducing power consumption.

Commonly used refrigerators have a freezing space to be cooled to about -18 to -20 ° C, and a refrigerating space or vegetable preservation space to be kept at +1 to + 5 ° C, and both rooms are cooled by a single cooler. Controlling the distribution of cold air flow into the refrigeration and refrigerating spaces by dampers, etc., driving or stopping the compressor according to the total load, and controlling the rotational speed of the compressor by inverter control and controlling both storage spaces to a predetermined temperature. Was keeping up.

Moreover, in the type provided with a cooler in each of the refrigerating and refrigerating spaces, the flow of refrigerant is switched to control the distribution of the coolant to the coolers arranged in the respective cooling spaces, and according to the load of the temperature and temperature difference of the entire cooling space. The compressor is being controlled.

On the other hand, the compressor used in the refrigeration refrigerator currently supplied in the market is a so-called single stage compression method in which a single compression unit exists in the compressor case, but recently, as shown in FIG. 13, a low stage compression element together with a motor in a sealed container. A two-stage compressor 39 having a 39a and a high stage compression element 39b is provided, and an expansion for intermediate pressure is provided on the outlet side of the condenser 40 connected to the discharge pipe 46 from the high stage compression element 39b. The apparatus 43 is connected and the discharge side of the low stage side compression element 39a and the suction side of the high stage side compression element 39b communicate with the suction pipe 47 for intermediate pressure, so that the medium pressure suction pipe 47 and the A medium pressure evaporator 35 is connected between the medium pressure expansion device 43 and a suction side 45 of the low pressure expansion device 42 of the two stage compressor and the low pressure expansion device 42 connected to the outlet side of the condenser 40. By connecting the low pressure evaporator 34 between the By communicating the discharge side of the low stage compression element 39a and the suction side of the high stage compression element 39b in the hermetically sealed container 39, the accuracy of temperature control in the refrigerator is increased, and the temperature of each part of the refrigerator is increased, and the efficiency of the high efficiency and low power consumption are increased. The idea of a two-stage compressed refrigeration apparatus has been disclosed (for example, Japanese Patent Laid-Open No. 2001-74325).

(Tasks to be solved by the invention)

In the refrigerating cycle described in Japanese Laid-Open Patent Publication No. 2001-74325, the cycle efficiency is improved by making the evaporation temperature of the intermediate pressure evaporator 35 that is a refrigeration cooler higher than the evaporation temperature of the low pressure evaporator 34 that is a refrigeration cooler. However, the suction pipe of the refrigeration cooler 34 by the two-stage compression cycle is directly connected to the compressor 39a at the lower stage of the compressor, and the suction pipe 47 of the refrigeration cooler 35 is connected to the intermediate pressure of the compressor 39. Since it is connected, the freezing capacity of the refrigerating space is hardly influenced by the refrigerant flowing to the refrigerating cooler 35, and in the conventional method of controlling the rotation speed of the compressor 39 at the total load of the freezing side load and the refrigerating side load. For example, when the degree of cooling of the refrigerating space is sufficient and the refrigerating space is excessively cooled, the number of revolutions of the compressor is reduced, resulting in a problem that the cooling of the freezing space is insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and by controlling the capacity variable refrigeration cycle of refrigeration and refrigerating chillers and having a two-stage compression type according to the freezing space temperature information, the freezing space and the refrigerating space are stored at respective storage temperatures. It is an object of the present invention to provide a refrigerator which can be properly controlled.

(Means to solve the task)

In order to solve the above problems, the refrigerator of the present invention has a compressor having a variable capacity compressor driven by an inverter comprising a low stage compression unit and a high stage compression unit, and a refrigerant passage provided at an outlet side of a condenser receiving discharge gas from the compressor. Rotation of the compressor according to the freezing space temperature and the target value in a refrigerator having a refrigeration cycle formed from a switching valve for controlling the flow rate and a refrigeration cooler and a refrigerating cooler respectively connected from the switching valve via a decompression device. It is characterized by determining the number.

In addition, the refrigerator according to the invention of claim 2 is characterized in that the compressor has a variable capacity compressor driven by an inverter comprising a low stage compression unit and a high stage compression unit, and a refrigerant passage provided at an outlet side of a condenser receiving discharge gas from the compressor. A switching valve for controlling the flow rate, and a refrigerator having a freezing cycle from a freezing cooler and a refrigerating cooler respectively connected from the switching valve via a decompression device, the freezer space temperature and its target value together with the freezer space temperature and The rotation speed of the compressor is determined based on the target value, and the amount of feedback of the temperature information on the side of the freezing space is larger than that of the refrigerating space when the rotation speed is determined.

(Effects of the Invention)

With the above configuration, both of the freezing and refrigerating coolers are evaporated temperatures suitable for the cooling of each storage space, and the refrigerant flow control such as the flow path to each cooler and the flow rate can be controlled while improving the efficiency of the refrigeration cycle. By simultaneously cooling the freezing space and the refrigerating space, temperature fluctuations in each space can be suppressed, and each space temperature can be appropriately controlled.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of this invention is described based on drawing. The refrigerator main body 1 shown in the longitudinal cross-sectional view of FIG. 2 forms a storage space inside the heat insulation box, and the freezing space 2 of the freezer compartment or the ice-making compartment, the refrigerating compartment 3 of the refrigerator compartment or the vegetable compartment by the partition wall. It is divided into a plurality of storage rooms.

Each storage compartment is cooled and maintained at a predetermined set temperature by the refrigerator cooler 4, the refrigerator cooler 5, and the cold air circulation fans 6 and 7 arranged in each of the freezing space and the refrigerating space. , 5) is cooled by the refrigerant supplied from the compressor 9 provided in the machine room 8 in the lower part of the main body rear surface.

1 shows a refrigerating cycle in the refrigerator of the present invention, wherein the compressor 9, the condenser 10, the switching valve 11 of the refrigerant flow path and the refrigerating and refrigerating coolers 4 connected in parallel. , 5) is connected in an annular shape. The condenser 10 has a flat plate shape and is installed in an outer bottom space of the refrigerator main body 1 in front of the machine room 8, and the refrigerant liquefied in the condenser 10 is switched through the switching valve 11, respectively. It is supplied to the freezing cooler 4 or the freezing cooler 5 through the capillary tubes 12 and 13, which are pressure reducing devices, and evaporated to lower the cooler, and the inside of the storage compartment by circulation by the cold air fans 6 and 7. Is cooled to a predetermined air temperature, and the vaporized refrigerant is configured to return to the compressor 9 through the accumulator 14 again.

However, as shown in FIG. 3, the compressor 9 is a recipe-type two-stage compressor composed of a low stage compression unit 9a and a high stage compression unit 9b, as shown in FIG. The connecting rod 9g is reciprocated by the eccentric shaft 9f which is eccentrically rotated by the rotation of the rotary shaft 9e of the electric mechanism 9d accommodated in 9c).

The piston 9i is inserted and fixed at the distal end of the connecting rod 9g by the ball joint 9h, and the low end compression section 9a and the high end compression are caused by the reciprocating movement of the piston 9i in the cylinder 9j. By alternately sucking, compressing and discharging the refrigerant to the portion 9b, by employing the ball joint 9h to the compression portion, the volumetric efficiency is improved and the two compression portions 9a and 9b are required. The expansion of the external space of the two stage compressor 9 is suppressed.

A suction port 9k of the low stage side compression section 9a is connected to an end of the suction pipe 15 connected from the freezer cooler 4 via the accumulator 14, and discharges the discharge port of the compressed refrigerant gas. 9m is opened in the case 9c, and the discharge port 9n of the high stage side compression part 9b is connected to the discharge pipe 16 to the condenser 10. As shown in FIG.

The accumulator 14 separates the gas liquid, stores the liquid refrigerant which has not evaporated in the cooler 4, sends only the gaseous refrigerant, and introduces the liquid refrigerant into the cylinder 9j of the compressor 9. In the present embodiment, only the rear end of the refrigeration cooler 4 is provided.

The suction pipe 17 from the refrigerating cooler 5 is connected to introduce a coolant into a space to be intermediate pressure in the sealed case 9c. Therefore, since the suction refrigerant from the refrigeration cooler 5 does not directly flow into the cylinder of the compressor, it is not necessary to install an accumulator at the rear end of the refrigeration cooler 5, and when it is installed, it may be small. Subsequently, the suction port of the high stage compression section 9b communicating with the refrigerant gas discharged from the discharge port 9m of the low stage compression section 9a communicates with the refrigerant gas sucked from the suction pipe 17 on the refrigeration cooler side ( It is configured to be sucked into 9p) and compressed.

The compressor 9 is variable in capacity by inverter control, and determines the rotation frequency, for example, between 30 and 70 Hz based on the detected temperature of the freezing and refrigerating space, the difference from the target set temperature, the temperature change rate, and the like. It is operated by the control device which consists of a microcomputer.

The switching valve 11 is installed at the outlet side of the condenser 10 receiving the discharge gas from the compressor 9 to control the flow rate along with the refrigerant flow path to the cooler 4 and 5 side, as shown in FIG. As described above, in the valve case 18, a valve seat 19 having a valve port A 19a to the refrigeration cooler 4 side and a valve port B 19b to the refrigerating side cooler 5 is provided. This is a three-way valve in which the valve body 20 is disposed above the seat 19.

The valve body 20 extends in an arc shape over a predetermined length so as to correspond to the valve tool A 19a and the valve tool B 19b on the rotational trajectory, respectively, and has a rotational radius different from the center of the rotation shaft 20c. It is formed on the lower surface of the thick step portion 20d formed by forming two cross-sectional V-shaped concave grooves A 20a and concave grooves B 20b into a predetermined short edge shape, and the upper surface of the valve seat 19 The valve body 20 is brought into close contact with each other, and is rotated in a pulse step of 0 to 85 by a stepping motor (not shown) provided in the upper portion.

The switching valve 11 rotates the valve body 20 in the pulse signal by the refrigeration cycle control signal, and the recess A 20a and the valve mechanism A 19a outside the rotation radius of the valve body at a predetermined pulse position. When the upper and lower surfaces communicate with each other, the refrigerant flowing into the valve case 18 from the inlet valve opening 21 is recessed in a V shape from the open end edge of the thick step portion 20d of the recessed groove A 20a. It enters into the groove A 20a, flows out from the valve port A 19a communicating with the recessed groove A, is introduced into the freezing capillary 12, and evaporated and evaporated in the freezing cooler 4.

On the other hand, when the concave groove B (20b) and the valve port B (19b) of the inside of the turning radius is in communication with each other, the refrigerant introduced into the concave groove (20b) is a cooling capillary tube ( 13) and evaporates in the refrigeration cooler (5).

Further, the concave groove B 20b on the refrigerating side is formed so that its cross-sectional area is gradually enlarged as the V-shaped groove is directed from the rotation end toward the open end of the thick step portion 20d. It is made to rotate from the minimum to the maximum flow opening area to communicate with the valve port B 19b. Since the flow path switching and the flow rate adjustment can be controlled very precisely, the refrigerant flow rate is efficiently controlled by the rotation control by the pulse. You can change it linearly.

Control of the opening of the valve in the three-way valve 20 allows the opening degree of the valves 19a and 19b to the refrigeration cooler 4 and the refrigerating side cooler 5 to be fully open, or fully closed, and to the freezing side valve. Various patterns can be selected, such as throttle the opening to fully open the refrigerating side, or throttle the refrigeration side to the valve opening, to fully open the freezing side. However, in this embodiment, the freezing cooler 4 and the refrigerating cooler 5 are selected. Are connected in parallel, and cooling control is made into two types of simultaneous cooling on the freezing refrigerating side and cooling only on the freezing side.

The refrigerant flowing out of the refrigeration side valve port A (19a) is decompressed through a capillary tube (12) set to be an evaporation temperature based on the cooling temperature in the freezing space (2) and is reduced to -25 ° C in the freezing refrigerator (4). Evaporate to a degree and refrigeration through the refrigerating capillary tube 13 which is set so that the evaporation temperature of -5 degreeC approximates to the cooling temperature in the refrigerating space 3 also from refrigeration valve port B19b. The refrigerant flows into the cooler 5 and evaporates.

In addition, the freezing and refrigerating capillary tubes 12 and 13 in the refrigerating cycle are used to provide a temperature difference to the refrigerant evaporation temperature in the freezing cooler 4 and the refrigerating cooler 5. As a result of the throttle being strong, when the refrigerant flows in both the refrigeration and cooling as described above, the refrigerant tends to easily flow to the refrigeration side with low resistance, and the refrigerant tends to be difficult to flow on the freezing side. There is a situation where the refrigerant does not flow.

In order to improve this, the switching valve 11 controls the refrigerant flow for cooling each of the refrigerating and refrigerating spaces 2 and 3, and in order to prevent a so-called deflection of the refrigerant flow, the refrigerant flow rate toward the refrigerating side where the refrigerant is likely to flow. We're doing some control to throttle a bit.

When the concave groove A 20a and the valve port A 19a on the freezing side communicate with each other and are completely opened, the refrigeration side cooler 4 has almost no freezing capacity. The refrigeration capacity of the refrigerating side can be obtained, and the range from closing to opening due to the communication state between the recessed groove B 20b of the selector valve 11 and the valve port 19b and the rotation speed of the compressor 9 can be obtained. Change is extremely fine control.

By controlling the refrigerant flow, the evaporation temperature of the refrigerating cooler 5 can be set to a high temperature with a temperature difference with the freezing side, and the refrigerating chamber temperature can be cooled to 1 to 2 ° C., but the heat transfer of the refrigerating cooler 5 is performed. It is also possible to increase the evaporation temperature further by increasing the surface area to increase the heat exchange amount for cooling the refrigerating space, and in this case, the temperature difference between the cooling temperature of the refrigerating space 3 and the cooler temperature becomes smaller and thus the refrigerating cooler 5 The amount of frost adhering to it is reduced, and it has the effect of preventing the drying in space and keeping humidity in a high place.

In addition, since the freezing capacity required for the cooling of the freezing space and the refrigerating space is almost the same in a general home refrigerator, the heat transfer surface area of the refrigerating cooler 5 is equal to or larger than that of the refrigerating cooler 4, whereby each cooling space is provided. Can be efficiently cooled.

Next, the operation of the refrigeration cycle will be described. When the compressor 9 is driven by turning on the power, the refrigerant gas, which has been compressed and becomes high temperature and high pressure, is discharged from the discharge tube 16 to the condenser 10 and reaches the switching valve 11. Although the switch valve 11 can be set in various patterns as described above, since the refrigeration and refrigerating spaces 2 and 3 are both uncooled at the time of power supply, the valve ports A 19a and B 19b are In the fully open state, the refrigerant flows into the freezing and refrigerating capillaries 12 and 13 and is decompressed, respectively, into the freezing and refrigerating coolers 4 and 5 and evaporates at each evaporation temperature. Cool to temperature.

Refrigerant from the freezer cooler 4 flows into the accumulator 14, and if a liquid coolant that has not evaporated completely in the cooler remains, it is stored in the accumulator 14, and only the gas coolant is a suction pipe. It is sucked into the low stage compression part 9a of the compressor 9 from (15). In addition, the gas refrigerant evaporated in the refrigerating cooler 5 is introduced into the sealed case 9c having the intermediate pressure of the compressor 9 via the suction pipe 17.

The intermediate pressure portion of the sealed case 9c from the refrigeration cooler 5 and the refrigerant gas sucked into the low stage compression part 9a from the freezing cooler 4 and compressed and discharged into the case 9c from the discharge port 9m. The refrigerant gas introduced into the gas is joined to the high stage side compression section 9b from the suction port 9p, compressed, discharged from the discharge port 9n to the discharge tube 16, and formed into a condenser 10. do.

Therefore, according to the refrigerating cycle, the refrigerating and refrigerating coolers 4 and 5 having the capillary tubes 12 and 13 are respectively provided such that the evaporation temperature is adjusted to the respective set temperatures of the refrigerating space 2 and the refrigerating space 3. And the refrigerant gas evaporated in the refrigerating cooler 5 is directly sucked to the intermediate pressure in the compressor case 9c in a state of medium pressure having a higher pressure than the freezing side, whereby the evaporation temperature of the refrigerating cooler 5 is reduced. Not only can the refrigeration cooler 4 be made high on the basis of the room cooling temperature, but also the compressor input is reduced, so that the cycle efficiency can be increased and the power consumption can be reduced.

In addition, by increasing the evaporation temperature of the refrigerating cooler (5) to reduce the temperature difference with the refrigerating space to reduce the amount of frost attached to the cooler (5), to prevent drying in the refrigerating space to maintain high humidity in the high, Since the food freshness can be maintained for a long time, and the refrigerant can be simultaneously cooled by both of the freezing and refrigerating coolers 4 and 5, the temperature fluctuation of each room can be suppressed as compared with the conventional alternate cooling method. can do.

In addition, the refrigeration cycle, as shown in Fig. 5 with the same reference numerals as in Fig. 1, for the compressor 9, the condenser 10, the switching valve 11 of the refrigerant flow path for the refrigeration cooler (4) And a refrigeration cooler 10 connected in series, and a side pipe 22 for bypassing the refrigerating capillary 13 and the refrigerating cooler 5 from the switching valve 11 through the gas-liquid separator 23. The capillary tube 12 may be connected to the freezing cooler 4, and the upper portion of the gas-liquid separator 23 and the space portion, which is an intermediate pressure portion in the sealed case 9c of the compressor 9, may be connected to the suction tube 24.

In this way, the refrigerant flows simultaneously or selectively to the refrigerating cooler 5 and the refrigerating cooler 4 by the switching valve 11 controlled in the same manner as described above, and the side pipe 22 or the refrigerating cooler ( The refrigerant from 5) is separated into a gaseous refrigerant and a liquid refrigerant in the gas-liquid separator 23, the liquid refrigerant flows to the freezing cooler 4 side, and the gaseous refrigerant flows in the middle of the compressor 9 through the refrigeration side suction pipe 24. The liquid refrigerant is returned to the pressure portion and the liquid refrigerant evaporates at a low temperature in the freezing cooler 4 and returns to the low stage side of the compressor 9 again. As in the above-described embodiment, the cycle efficiency is improved and the inside of each storage chamber is maintained at a predetermined temperature. It has a cooling effect.

6 shows the freezing side when the compressor 9 is operated at a predetermined rotational speed with the evaporation temperature of the freezing cooler 4 and the refrigerating cooler 5 as well as the condensing temperature of the condenser 10 being a constant value. And the freezing capacity on the refrigeration side, and the freezing capacity on the refrigeration side on the vertical axis and the freezing capacity on the freezing side on the horizontal axis. In the figure, point a represents a case where the refrigerant flows only to the refrigerating side cooler 5 by a switching valve, and point b represents a case where the refrigerant flows only to the freezing side cooler 4, and point c represents a freezing and refrigerating cooler. The case where the refrigerant | coolant flowed in the valve opening 19a, 19b in the fully open state in both (4, 5) is shown.

In the graph, the mass or volume of the refrigerant sucked directly from the freezer cooler 4 to the low stage compression unit 9a of the compressor 9 is determined by the cylinder exclusion volume of the low stage compression unit, and the corresponding freezing force is the freezing force. While only 69W flows on the side, it is 64W when the refrigeration is simultaneously flown, and it is almost constant without being affected by the refrigerant returning from the refrigerating cooler 5 to the intermediate pressure portion of the compressor 9. .

On the other hand, in the refrigerating side, the refrigerating force corresponding to the amount of refrigerant sucked into the compressor 9 from the refrigerating cooler 5 is 155 W only in the refrigerating side, whereas the refrigerating side is greatly reduced to about 75 W in the case of simultaneous refrigeration flow. The refrigerating capacity on the refrigerating side varies greatly depending on the presence or absence of the refrigerant sucked from the freezing cooler 4, that is, only the refrigerant from the refrigerating cooler 5 or the amount of confluence with the refrigerant sucked from the freezing cooler 4. do.

In addition, in general, the indoor temperature of the refrigerating space is +3 ~ 5 ℃, whereas the freezing space temperature is -18 ~ -20 ℃ temperature difference with the outdoor temperature increases, the freezing capacity required for cooling the freezing space is the refrigerating space In the case where the freezing capacity on the freezing side is greater than the freezing capacity on the refrigerating side, that is, when the load on the freezing side is set to be larger than the refrigerating side, the freezing operation is schematically shown in FIG. As shown in Fig. 7, the portion of the diagonal region in the drawing, which is a region having a large freezing capacity on the freezing side, is used.

Therefore, as described above, the refrigeration side refrigeration capacity is less likely to be affected by the refrigerant returned from the refrigerating cooler 5, so that the cooling control of the refrigerating space may be controlled by the rotation speed of the compressor 9. In the case of shortage, as shown by the arrow, the rotation speed of the compressor 9 is increased to increase the freezing capacity, and in the case of excessive cooling, the cooling temperature can be properly maintained by decreasing or stopping the rotation speed. The refrigerating side controls the cooling temperature by adjusting the refrigerant flow rate in the opening and closing control of the valve opening of the switching valve 11 instead of the rotation speed of the compressor 9.

An embodiment of the compressor speed control of the present invention will be described with reference to FIG. 8, which is a control block diagram. The freezing space detected by the cold temperature sensor, for example, the room temperature Fa of the freezing compartment 4 is compared with a predetermined target value Fr, and the deviation is transmitted to the PID controller 25 for determining the frequency of the compressor. Is entered.

If the temperature of the freezing space 2 is higher than the target value Fr, the PID calculated value increases due to the deviation and the rotational speed of the compressor 9 is increased by a predetermined amount to promote the cooling of the freezing space 2 and to maintain the predetermined temperature. Control your driving to lead to. When the temperature of the freezing space 2 is lower than the target value Fr, the rotation speed is lowered or stopped to decrease the freezing force.

Next, another embodiment of the compressor rotation speed control of the present invention will be described. In the above embodiment, the rotation speed of the compressor 9 is controlled by the temperature information of the freezing space 2. However, depending on the operating conditions of the refrigerator, the freezing capacity of the refrigerating space 3 with respect to the freezing space 2 is reduced. Inadequate cases are also considered.

Thus, when the compressor 9 is operated in the diagonal region in FIG. 7 by inputting the temperature information of the refrigerating space 3 together with the temperature information of the freezing space 2, the rotation speed of the compressor 9 is increased to increase the freezing capacity. By increasing the cooling capacity of the refrigerating space (3) together with the freezing space (2) can also be increased.

However, the increase in the number of revolutions of the compressor 9 when the freezing space 2 is cooled below the target value unnecessarily cools the freezing space 2, resulting in unnecessary power consumption. In one block diagram, the refrigerating space temperature Ra and its target value Rr are input to the PID controller 25 together with the freezing space temperature Fa and its target value Fr. Feedback of the temperature information data on the freezing space 2 side than the refrigerating space 3 is inputted by adding twice the deviation data value between the internal temperature Fa and the target temperature Fr on the freezing space side, for example, to be inputted. The amount is increased.

Thereby, the rotation speed of the compressor 9 is determined based on the refrigeration side by the feedback temperature information of the refrigeration space 2 side, which is a deviation value considered larger than the actual value, but the refrigeration space 2 is sufficiently cooled. In this case, by controlling the coolant flow to the refrigerating cooler 5 by the selector valve 11 without increasing the rotation speed of the compressor 9, the refrigerating side is increased without increasing the refrigerating side of the refrigerating side and causing the refrigerating side to be overcooled. The control is to maintain the proper temperature.

In addition, in the above embodiment, the temperature information of the refrigerating space 3 is added to determine the rotation speed of the compressor 9. However, if the external temperature is lowered, the temperature of the refrigerating space 3 is set to the target value Rr. In the case of lowering, the rotation speed of the compressor 9 is lowered by the feedback signal, and as a result, a problem occurs that the freezing capacity of the freezing space 2 side is lowered.

FIG. 10 is a block diagram corresponding to such a case, and is introduced into the function Fx for feeding back the temperature information only when the temperature of the refrigerating space 3 is higher than the target value Rr, and the refrigerating space temperature. If the difference between Ra and the target value Rr is small, the value is input, but if it is a negative value, a zero signal is input to the PID controller 25.

Even if the load of the refrigerating space 3 is light and the actual temperature Ra is lower than the target set value Rr by this control, the freezing space 2 maintains the target value Fr by the freezing force based on the temperature information. The temperature of the freezing space 2 can be prevented from being higher than the target value Fr due to the decrease in the freezing force.

Further embodiments will be described. 11 shows the freezing capacity (QF1, QR1) of the freezing and refrigerating cycles when the compressor 9 is operated at a certain rotational speed and the temperature of the refrigerating cooler 5 is changed under a condition where the condensation temperature is constant. ) Is shown.

At this time, the refrigerating cooler 5 can lower its freezing capacity QR1 by lowering its surface temperature and increase its freezing capacity by increasing its surface temperature. It can be seen that the cooler temperature is constant at, for example, -23.5 ° C and is not significantly affected by the change in the freezing capacity on the refrigerating side.

For the refrigerating cooler 5, if the rotational speed of the refrigerating fan 7 is changed, for example, the rotational speed is lowered, the amount of heat exchange in the refrigerating cooler 5 is lowered and the surface temperature of the cooler 5 is lowered. As a result, the refrigerating capacity QR1 of the refrigerating cycle is also lowered. Conversely, if the rotation speed of the fan 7 is increased, the heat exchange amount is increased so that the surface temperature of the cooler 5 is increased and the refrigerating capacity QR1 of the cycle is increased. .

That is, in the cooling control of the refrigerating space 3, the space temperature can be controlled by increasing or decreasing the rotation speed of the refrigerating fan 7, and when the refrigerating space temperature Ra is higher than the target value Rr. It is possible to cool by increasing the rotation speed of the refrigerating side cooling fan 7, and when it is subcooled below the target value Rr, the cooling power can be weakened and the control can be controlled to a predetermined appropriate temperature by lowering the fan rotation speed. .

12 shows the change in the freezing capacity (QF2, QR2) of the freezing and refrigerating cycle when the temperature of the freezing cooler 4 is changed, and by lowering the temperature of the freezing cooler 4, The refrigerant circulation amount sucked into the low end side of the compressor 9 through the freezing cooler 4 is reduced, and the freezing capacity QF2 of the freezing side cycle is lowered. In addition, since the amount of refrigerant sent to the high stage compression section from the low stage side of the compressor 9 also decreases, the refrigerant is returned to the intermediate pressure section from the refrigerator 5 for cooling in the high stage compression section due to the exclusion volume of the high stage compression section. The amount of refrigerant is increased, and the freezing capacity QR2 of the refrigeration side cycle is increased.

Advantageously, when the temperature of the refrigerating space 3 is higher than the target value Rr and the cooling is insufficient, or when the freezing force of the freezing space 2 is excessive, the rotation speed of the freezing side cooling fan 6 is lowered, By reducing the amount of heat exchange in the freezer cooler 4 and lowering the surface temperature of the cooler 4, the cycle capacity on the refrigeration side (QR2) is increased, or the refrigeration side cycle capacity (QF2) is lowered and the respective cooling is performed. The space can be controlled to an appropriate temperature.

By the above, the freezing space (2) and the refrigerating space (3) has a cycle efficiency in that the evaporation temperature can be increased by simultaneously flowing the refrigerant to the refrigerating cooler (5) together with the refrigerant flow to the refrigerating cooler (4). It is possible to cool properly, and even for temperature loads that are occasionally introduced into each storage space, the temperature fluctuations in the freezing space and the refrigerating space can be suppressed by distributing the appropriate amount of refrigerant by the refrigerant flow control switching valve 11 composed of three-way valves. Space temperature can be controlled appropriately.

In the refrigerating cycle described above, it is possible to control the flow of refrigerant to both the freezing and refrigerating coolers 4 and 5 simultaneously, so that the refrigerant is supplied to one cooler as compared to the control of flowing the coolant to the two coolers alternately. It is not biased and the amount of refrigerant required for the refrigeration cycle does not increase more than necessary. Therefore, even when a flammable refrigerant such as a hydrocarbon refrigerant is employed, the amount of refrigerant charge can be reduced, thereby improving safety.

In addition, although the pressure in the compressor case 9c was demonstrated that the pressure in the compressor case 9c is an intermediate pressure in the said Example, it is not limited to this, Although it does not show in figure, the suction pipe from a refrigeration cooler as a low pressure case is a space in a compressor case. The suction pipe from the refrigerator for cooling may be connected to the connection portion between the discharge port of the low stage compression section and the suction port of the high stage compression section. Similarly, the suction tube from the freezer cooler is connected to the suction port of the low stage compression section as a high pressure case, and the suction tube from the refrigeration cooler is connected to the connection portion of the discharge port of the low stage compression section and the suction port of the high stage compression section. The discharge gas from the portion may be discharged from the high pressure case to the discharge tube to the condenser.

According to this invention, it can use for the refrigerator which improved cycle efficiency by the two-stage compression type refrigeration cycle structure.

(Short description of the drawing)

1 is a refrigeration cycle diagram of a refrigerator showing one embodiment of the present invention;

FIG. 2 is a schematic longitudinal sectional view of the refrigerator equipped with the refrigeration cycle of FIG. 1;

3 is a longitudinal sectional view showing the details of the two stage compressor in FIG. 1;

4 is a plan view showing details of main parts of the three-way valve in FIG. 1;

5 is a configuration diagram showing another embodiment of the refrigeration cycle,

6 is a relationship graph between refrigeration and refrigerating side refrigeration capacity and refrigerants;

7 is a schematic view of FIG. 6,

8 is a block diagram of compressor rotation speed control,

FIG. 9 is a rotation speed control block diagram in which refrigeration temperature information is added to the control of FIG. 8; FIG.

10 is a rotation speed control block diagram further improving the control of FIG.

11 is an explanatory view showing a change in freezing and refrigerating freezing capacity when the refrigerating cooler temperature of the present invention is changed;

 12 is an explanatory diagram showing a change in freezing and refrigerating freezing capacity when the freezing cooler temperature of the present invention is changed, and

13 is a refrigeration cycle diagram of a conventional refrigerator.

* Explanation of symbols for the main parts of the drawings

1: refrigerator body 2: freezer space

3: refrigerating space 4: refrigeration cooler

5: chiller 6, 7: cooling fan

8: machine room 9: two stage compressor

9a: low stage compression unit 9b: high stage compression unit

9c: case 10: condenser

11: switching valve 12: refrigeration capillary

13: refrigeration capillary 14: accumulator

15: refrigeration side suction tube 16: discharge tube

17, 24: refrigeration side suction pipe 18: valve case

19: valve seat 19a: refrigeration side valve port A

19b: Refrigerating side valve port B 20: Valve body

20a: Refrigeration side recessed groove A 20b: Refrigeration side recessed groove B

20c: axis of rotation 20d: thick end

21: inlet valve port 22: side pipe

23: gas-liquid separator 25: PID controller

Claims (5)

Compressor of variable capacity by inverter drive consisting of low stage side compression section and high stage side compression section, switching valve for controlling flow rate together with refrigerant flow path installed at outlet side of condenser receiving discharge gas from said compressor, said switching valve In the refrigerator which formed the refrigerating cycle with the refrigerator | cooler for refrigeration and the refrigerator | cooler for refrigeration respectively connected through the decompression device from And a rotation speed of the compressor is determined by a freezing space temperature and a target value thereof. Compressor whose variable capacity is driven by an inverter drive consisting of a low stage side compression unit and a high stage side compression unit, a switching valve for controlling the flow rate along with a refrigerant flow path installed at an outlet side of a condenser receiving discharge gas from the compressor, the switching valve In the refrigerator which formed the refrigerating cycle with the refrigerator | cooler for refrigeration and the refrigerator | cooler for refrigeration respectively connected through the decompression device from The rotational speed of the compressor is determined by the refrigerating space temperature and the target value together with the freezing space temperature and the target value. When the rotational speed is determined, the feedback amount of the temperature information on the freezing space side is larger than the refrigerating space. Refrigerator. The method of claim 2, A refrigerator, characterized in that the temperature information is employed to determine the compressor rotation speed only when the refrigerator space temperature is higher than the target value. The method according to any one of claims 1 to 3, The refrigerator characterized in that the number of revolutions of the refrigeration-side cooling fan is increased when the refrigerated space temperature is higher than the target value. The method according to any one of claims 1 to 4, And when the refrigerating space temperature is higher than the target value, the rotation speed of the freezing side cooling fan is reduced.

Images