JP2005188783A - Refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerator capable of properly controlling a freezing space and a refrigeration space respectively at their storage temperatures by controlling a two-stage compression type capacity-variable refrigeration cycle having a cooling unit for freezing and a cooling unit for refrigeration on the basis of freezing space temperature information. <P>SOLUTION: In this refrigerator wherein the freezing cycle is composed of a capacity-variable compressor 9 having a compressing element composed of a low stage-side compressing part 9a and a high stage-side compressing part 9b and driven by an invertor, a switch valve 11 mounted at an outlet side of a condenser 10 receiving a discharge gas from the compressor and controlling a flow rate with a refrigerant flow channel, and the cooling unit 4 for freezing and the cooling unit 5 of refrigeration respectively connected from the switch valve through decompression devices 12, 13, a rotational frequency of the compressor is determined on the basis of a freezing space temperature Fa and its target value Fr. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a refrigerator using a two-stage compression type variable capacity compressor, and more particularly to a refrigerator that determines the rotation speed of a compressor according to a storage space temperature.

  In recent years, refrigerators are often equipped with a variable capacity compressor by inverter control. By varying the refrigeration capacity, cooling performance corresponding to the load is obtained and power consumption is reduced.

  Refrigerators that are widely used for home use generally have a freezing space that is cooled to about -18 to -20 ° C and a refrigerated or vegetable storage space that is maintained at about +1 to + 5 ° C. In the case of cooling both spaces with a cooler, the distribution of the cold air flow to the refrigeration and refrigeration space is controlled by a damper or the like, the compressor is driven or stopped according to the overall load, and the inverter control further Both storage spaces were maintained at a predetermined temperature by controlling the rotation speed of the compressor.

  Further, in a type in which a refrigerator is provided in each of the refrigeration and refrigeration spaces, distribution control of the refrigerant flow to the coolers arranged in the respective cooling spaces is performed by switching the refrigerant flow paths, and the temperature of the entire cooling space can be controlled. The compressor is controlled according to the load such as temperature difference.

On the other hand, the refrigerant compressor currently used in the refrigerator-freezer on the market is a so-called one-stage compression system in which a single compression unit is present in the compressor case. As shown, a two-stage compressor (39) having a motor, a low-stage compression element (39a), and a high-stage compression element (39b) is provided in a sealed container, and a discharge pipe from the high-stage compression element (39a). An intermediate pressure expansion device (43) is connected to the outlet side of the condenser (40) connected to (46), and the discharge side of the low-stage compression element (39a) and the suction side of the high-stage compression element (39b) An intermediate pressure suction pipe (47) is communicated, and an intermediate pressure evaporator (35) is connected between the intermediate pressure suction pipe (47) and the intermediate pressure expansion device (43), and a condenser (40 ) Between the low pressure expansion device (42) connected to the outlet side and the suction side (45) of the low-stage compression element of the two-stage compressor The low-pressure evaporator (34) is connected to the container, and the discharge side of the low-stage compression element (39a) and the suction side of the high-stage compression element (39b) are communicated with each other in the sealed container (39). The idea of a two-stage compression refrigeration system that increases the accuracy of temperature control in the interior and makes the temperature of each part in the cabinet uniform, high efficiency, and low power consumption is disclosed. (For example, see Patent Document 1)
JP 2001-74325 A

  In the refrigeration cycle described in Patent Document 1, cycle efficiency is improved by making the evaporation temperature of the intermediate pressure evaporator (35), which is a refrigeration cooler, higher than the low pressure evaporator (34), which is a refrigeration cooler. To do. However, the suction pipe of the refrigeration cooler (34) in the two-stage compression cycle is directly connected to the lower stage compression section (39a) of the compressor, and the suction pipe (47) of the refrigeration cooler (35) is connected to the compressor (39 ), The refrigeration capacity of the refrigeration space is not easily affected by the refrigerant flowing into the refrigeration cooler (35), and the total of the load on the refrigeration side and the load on the refrigeration side In the conventional method of controlling the rotation speed of the compressor (39) with the load, for example, when the cooling degree of the refrigeration space is sufficient and the refrigeration space is excessively cooled, the rotation speed of the compressor is reduced. As a result, there has been a problem that cooling of the freezing space is insufficient.

  The present invention has been made in consideration of the above points, and by controlling a variable capacity refrigeration cycle having a refrigeration and refrigeration cooler and a two-stage compression type based on refrigeration space temperature information, An object of the present invention is to provide a refrigerator in which the refrigerated space can be appropriately controlled at each storage temperature.

  In order to solve the above-described problems, a refrigerator according to the present invention includes an inverter-driven compressor having a variable compression element composed of a low-stage side compression unit and a high-stage side compression unit, and a discharge gas from the compressor. A refrigeration cycle is formed from a switching valve for controlling the flow rate together with a refrigerant flow path provided on the outlet side of the condenser to be received, and a refrigeration cooler and a refrigeration cooler connected from the switching valve via a pressure reducing device, respectively. In the refrigerator, the number of rotations of the compressor is determined based on the freezing space temperature and its target value.

  According to a second aspect of the present invention, there is provided a refrigerator having a variable capacity compressor driven by an inverter whose compression elements are constituted by a low-stage compression section and a high-stage compression section, and a condenser that receives discharge gas from the compressor. In a refrigerator that forms a refrigeration cycle from a switching valve that controls the flow rate together with a refrigerant flow path provided on the outlet side of the refrigeration, and a refrigeration cooler and a refrigeration cooler that are connected to the switching valve via a decompression device, respectively. The compressor rotation speed is determined by the refrigeration space temperature and the target value together with the refrigeration space temperature and the target value. When the rotation speed is determined, the amount of feedback of temperature information on the refrigeration space side from the refrigeration space is determined. It is characterized by increasing.

  With this configuration, both the refrigeration cooler and the refrigeration cooler can be evaporated at temperatures corresponding to the cooling of each storage space, and the efficiency of the refrigeration cycle can be improved, and the flow of the refrigerant to the respective coolers can be controlled and the refrigerant flow can be controlled. In addition, the temperature fluctuation in each space can be suppressed by simultaneously cooling the refrigerated space and the refrigerated space, and each space temperature can be controlled appropriately.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The refrigerator main body (1) whose longitudinal cross-sectional view is shown in FIG. 2 forms a storage space inside the heat insulation box, and the partition wall separates the freezing space (2) of the freezing room and ice making room, and the refrigerating space of the refrigerating room and vegetable room. (3) and so on.

  Each storage room is cooled and held at a predetermined set temperature by a refrigeration cooler (4), a refrigeration cooler (5), and a cold air circulation fan (6) (7) arranged for each refrigeration space or refrigeration space. Each cooler (4) (5) is cooled by the refrigerant supplied from the compressor (9) installed in the machine room (8) at the lower back of the main body.

  FIG. 1 shows a refrigeration cycle in the refrigerator of the present invention. The compressor (9), the condenser (10), the refrigerant flow switching valve (11), and the refrigeration and The refrigeration coolers (4) and (5) are connected in an annular shape. The condenser (10) is flat and disposed in the outer bottom space of the refrigerator body (1) in front of the machine room (8). The refrigerant liquefied by the condenser (10) 11) is supplied to the refrigeration cooler (4) or the refrigeration cooler (5) via the capillaries (12) and (13), which are decompression devices, respectively, and evaporates to lower the temperature of the cooler. The storage chamber is cooled to a predetermined air temperature by circulation through the cold air fans (6) and (7), and the evaporated vaporized refrigerant is configured to return to the compressor (9) again through the accumulator (14). Yes.

  As shown in detail in FIG. 3, the compressor (9) has a reciprocating two-stage compression in which the compression element is composed of a low-stage compression section (9a) and a high-stage compression section (9b). The connecting rod (9g) is reciprocated by an eccentric shaft (9f) that rotates eccentrically by the rotation of the rotating shaft (9e) of the electric mechanism (9d) housed in the sealed case (9c). .

  A piston (9i) is fitted and fixed to the tip of the connecting rod (9g) by a ball joint (9h), and the piston (9i) in the cylinder (9j) is reciprocated with the low-stage compression section (9a). The refrigerant is alternately sucked into the stage side compression section (9b), compressed and discharged, and by adopting the ball joint (9h) to the compression section, the volume efficiency is improved, and the two compression sections ( The expansion of the external space of the two-stage compressor (9) that requires 9a) and (9b) is suppressed.

  The suction port (9k) of the low-stage compression section (9a) is connected to the end of the suction pipe (15) connected via the accumulator (14) from the refrigeration cooler (4), and is compressed. The discharge port (9m) for discharging the refrigerant gas is opened in the case (9c), and the discharge port (9n) of the higher stage compression section (9b) is connected to the discharge pipe (16) to the condenser (10). Connected.

  The accumulator (14) separates gas and liquid, stores the liquid refrigerant that could not be evaporated by the cooler (4), sends out only the gaseous refrigerant, and supplies the liquid refrigerant to the cylinder (9j) of the compressor (9). In this embodiment, it is provided only at the rear stage of the refrigeration cooler (4).

  The suction pipe (17) from the refrigeration cooler (5) is connected so as to be introduced into a space portion serving as an intermediate pressure in the sealed case (9c). Accordingly, since the refrigerant sucked from the refrigeration cooler (5) does not flow directly into the cylinder of the compressor, it is not particularly necessary to provide an accumulator after the refrigeration cooler (5). Things can be used. And the refrigerant | coolant gas suck | inhaled from the suction pipe (17) by the side of the refrigerator for refrigeration communicates with the refrigerant | coolant gas discharged from the discharge port (9m) of the said low stage | side compression part (9a). It is configured to be sucked into the suction port (9p) of (9b) and compressed.

  The compressor (9) is variable in capacity by inverter control, and has a rotational frequency between 30 and 70 Hz, for example, based on the difference between the detected temperature of the refrigeration and refrigerated spaces, the target set temperature, the temperature change rate, etc. And is operated by a control device including a microcomputer.

  The switching valve (11) is provided on the outlet side of the condenser (10) that receives the discharge gas from the compressor (9), and controls the flow rate together with the refrigerant flow switching to the coolers (4) and (5) side. As shown in FIG. 4, in the valve case (18), a valve port A (19a) to the refrigeration cooler (4) side and a valve port B (19b) to the refrigeration side cooler (5) are provided. This is a three-way valve that is provided with a valve seat (19) that is formed with a valve body (20) disposed above the valve seat (19).

  The valve body (20) extends in a circular arc over a predetermined length so as to correspond to the valve ports A (19a) and B (19b) on the rotation locus, and rotates from the center of the rotation shaft (20c). The groove A (20a) and the groove B (20b) having two V-shaped cross sections with different moving radii are formed on the lower surface of the thick step (20d) formed into a predetermined edge shape. The upper surface of the valve seat (19) and the valve body (20) are intimately polymerized, and are rotationally driven by 0 to 85 pulse steps by a stepping motor (not shown) provided on the upper portion.

  The switching valve (11) rotates the valve body (20) by a pulse signal based on the refrigeration cycle control signal, and the groove A (20a) and the valve port A (19a) outside the rotation radius of the valve body at a predetermined pulse position. ) Are superposed vertically and communicated with each other, the refrigerant that has flowed into the valve case (18) from the inlet valve port (21) is opened at the open end of the thick-walled step (20d) in the groove A (20a). It enters the V-shaped concave groove A (20a) from the edge, flows out from the valve port A (19a) communicating with the concave groove A, is introduced into the freezing capillary (12), and the freezing cooler (4) It will evaporate.

  On the other hand, similarly, when the concave groove B (20b) on the inner side of the rotation radius and the valve port B (19b) communicate with each other, the refrigerant flowing into the concave groove B (20b) is refrigerated from the communicating valve port B (19b). It flows into the capillary tube (13) and evaporates with the refrigeration cooler (5).

  Further, the concave groove B (20b) on the refrigeration side is formed such that the cross-sectional area thereof is expanded as the V-shaped groove is directed from the rotating tip toward the open end of the thick-walled step (20d), By rotating the valve body (20), the minimum and maximum flow opening area is communicated with the valve port B (19b), and the flow control and flow rate adjustment can be finely controlled. Can efficiently change the refrigerant flow rate linearly.

  The opening control of the three-way valve (20) is performed by fully opening or closing both the opening degrees of the valves (19a) and (19b) to the refrigeration cooler (4) and the refrigeration cooler (5). Various patterns can be selected, such as squeezing the side valve opening to fully open the refrigeration side, or squeezing the refrigeration side valve opening to fully open the refrigeration side. In this embodiment, the refrigeration cooler (4) and refrigeration are selected. The cooling device (5) is connected in parallel, and cooling control is performed in two ways: simultaneous cooling on the freezer side and cooling only on the freezer side.

  The refrigerant that has flowed out of the freezing side valve port A (19a) passes through the capillary tube (12) that is set to have an evaporation temperature corresponding to the cooling temperature in the freezing space (2), and is reduced in pressure in the freezing cooler (4). The refrigeration capillary tube (13) is set so as to evaporate at about -25 ° C and to reach an evaporation temperature of about -5 ° C, which is similar to the cooling temperature in the refrigeration space (3), similarly from the refrigeration valve port B (19b). ) To the refrigeration cooler (5) and evaporate.

  The refrigeration and refrigeration capillaries (12) and (13) in the refrigeration cycle have a temperature difference in the refrigerant evaporation temperature between the refrigeration cooler (4) and the refrigeration cooler (5). As a result of strengthening the throttle of (12), when the refrigerant is allowed to flow to both refrigeration and refrigeration as described above, it inevitably tends to flow to the refrigeration side having a low resistance, and tends to be difficult to flow to the refrigeration side. In extreme cases, the refrigerant may not flow on the freezing side.

  In order to improve this, in the switching valve (11), the refrigerant flow control for cooling each of the refrigeration and the refrigeration spaces (2) and (3) and the so-called single flow of the refrigerant are prevented, so that the refrigerant flows easily. A control is added to reduce the refrigerant flow rate to a little.

  If the concave groove A (20a) on the refrigeration side and the valve port A (19a) communicate with each other and are fully open, the refrigeration side cooler (4) is almost unaffected by the refrigerant flow state on the refrigeration side. A predetermined refrigerating capacity can be obtained, and the refrigerating capacity on the refrigeration side is also in a range from closed to open due to the communication state between the concave groove B (20b) of the switching valve (11) and the valve port (19b), and The compressor (9) can be finely controlled by changing the rotation speed.

  With the above refrigerant flow control, the evaporating temperature of the refrigeration cooler (5) can be increased with a temperature difference from the refrigeration side, and the refrigeration room temperature can be cooled to 1-2 ° C. If the heat transfer surface area of the vessel (5) is increased to increase the amount of heat exchange for cooling the refrigerated space, the evaporation temperature can be further increased. In this case, the refrigerated space (3) is cooled. The temperature difference between the temperature and the cooler temperature becomes smaller and the amount of frost adhering to the refrigeration cooler (5) is reduced, which has the effect of preventing the drying in the space and keeping the humidity in the cabinet high.

  In general refrigerators for home use, the refrigeration capacity required for cooling the refrigeration space and the refrigeration space is substantially the same. Therefore, the heat transfer surface area of the refrigeration cooler (5) is set to the refrigeration cooler (4). It becomes possible to cool each cooling space efficiently by making it equal to or larger than.

  Next, the operation of the refrigeration cycle will be described. When the compressor (9) is driven by turning on the power, the refrigerant gas compressed to high temperature and high pressure is discharged from the discharge pipe (16) to the condenser (10) and reaches the switching valve (11). The switching valve (11) can be set in various patterns as described above, but when the power is turned on, the freezing and refrigeration spaces (2) and (3) are in an uncooled state. (19a) and B (19b) are fully opened, and the refrigerant flows into the freezing and refrigeration capillaries (12) and (13) and is depressurized to flow into the freezing and refrigeration coolers (4) and (5), respectively. Then, it evaporates at each evaporation temperature and cools each cooler to a predetermined temperature.

  The refrigerant from the refrigeration cooler (4) flows into the accumulator (14). If liquid refrigerant that could not be evaporated in the cooler remains, it is stored inside the accumulator (14) and only the gas refrigerant is stored. Is sucked into the lower stage compression section (9a) of the compressor (9) from the suction pipe (15). Further, the refrigerant evaporated in the refrigeration cooler (5) is introduced into the hermetic case (9c) having an intermediate pressure of the compressor (9) through the suction pipe (17).

  The refrigerant gas sucked into the lower stage compression section (9a) from the refrigeration cooler (4), compressed, and discharged from the discharge port (9m) into the case (9c) and sealed from the refrigeration cooler (5) The refrigerant gas that has flowed into the intermediate pressure portion of the case (9c) merges and is sucked into the high-stage compression portion (9b) from the suction port (9p) and is compressed and discharged from the discharge port (9n) to the discharge pipe (17). To form a refrigeration cycle which is discharged to the condenser (10).

  Therefore, according to the refrigeration cycle, for the refrigeration and refrigeration each having the capillaries (12) and (13) so as to have the evaporation temperature in accordance with the set temperatures of the refrigeration space (2) and the refrigeration space (3). The coolers (4) and (5) are installed, and the refrigerant gas evaporated in the refrigeration cooler (5) is directly sucked into the intermediate pressure portion in the compressor case (9c) with the intermediate pressure higher than that on the freezing side. Thus, not only can the evaporating temperature of the refrigeration cooler (5) be increased in accordance with the indoor cooling temperature with respect to the refrigeration cooler (4), but the compressor input is reduced, so that the cycle efficiency is increased, Power consumption can be reduced.

  Further, by increasing the evaporation temperature of the refrigeration cooler (5) to reduce the temperature difference from the refrigeration space, the amount of frost adhering to the cooler (5) is reduced, and drying in the refrigeration space is prevented. The inside humidity can be kept high and the freshness of the food can be maintained for a long period of time. Furthermore, the refrigerant can be simultaneously poured into both the freezing and refrigeration coolers (4) and (5) for cooling. Therefore, temperature fluctuation in each room can be suppressed as compared with the conventional alternating cooling method.

  In addition, as shown in FIG. 5 which attached | subjected the same code | symbol to the same part as FIG. 1, a refrigerating cycle is with respect to the said compressor (9), a condenser (10), and the switching valve (11) of a refrigerant | coolant flow path. Refrigeration cooler (4) and refrigeration cooler (5) are connected in series, and bypass tube (22) bypassing refrigeration capillary tube (13) and refrigeration cooler (5) from switching valve (11) Is connected to the refrigeration cooler (4) from the refrigeration capillary (12) via the gas-liquid separator (23), and above the gas-liquid separator (23) and the sealed case ( You may make it connect the space part used as the intermediate pressure part in 9c) by a suction pipe (24).

  In this way, the refrigerant flows simultaneously or selectively into the refrigeration cooler (5) and the refrigeration cooler (4) by the switching valve (11) controlled in the same manner as described above. (22) or the refrigerant from the refrigeration cooler (5) is separated into a gaseous refrigerant and a liquid refrigerant in the gas-liquid separator (23), and the liquid refrigerant flows to the refrigeration cooler (4) side, The refrigerant passes through the refrigeration side suction pipe (24) and returns to the intermediate pressure portion of the compressor (9), and the liquid refrigerant evaporates again at a low temperature in the refrigeration cooler (4), and the lower stage of the compressor (9). It returns to the side, and there is an effect that the respective storage chambers can be cooled to a predetermined temperature with high cycle efficiency as in the above-described embodiment.

  FIG. 6 shows that the compressor (9) is operated at a predetermined rotational speed with the evaporating temperature of the refrigeration cooler (4) and the refrigeration cooler (5) and further the condensing temperature of the condenser (10) as constant values. The refrigeration capacity on the refrigeration side and the refrigeration side is shown with the refrigeration capacity on the ordinate and the refrigeration capacity on the refrigeration side on the horizontal axis. In the figure, point a shows the case where the refrigerant is flowed only to the refrigeration side cooler (5) by the switching valve, point b shows the case where it flows only to the refrigeration side cooler (4), point c is for freezing and refrigeration. A case is shown in which the refrigerant is allowed to flow to both the coolers (4) and (5) with the valve openings (19a) and (19b) fully opened.

  In this graph, the mass or volume of the refrigerant sucked directly from the refrigeration cooler (4) into the lower stage compression section (9a) of the compressor (9) is determined by the cylinder exclusion volume of the lower stage compression section. Yes, the corresponding refrigeration power is 69 W for the freezing side only, but 64 W for the freezing and refrigeration simultaneous flow, from the refrigeration cooler (5) to the intermediate pressure part of the compressor (9). It shows that it is almost constant without being affected by the returning refrigerant.

  On the other hand, on the refrigeration side, the refrigeration power corresponding to the amount of refrigerant sucked into the compressor (9) from the refrigeration cooler (5) is 155 W in the case of only the refrigeration side, while in the case of simultaneous freezing and refrigeration flow The refrigerating capacity on the refrigeration side is greatly reduced to about 75 W, and the presence or absence of refrigerant sucked from the refrigerating cooler (4), that is, only the refrigerant from the refrigerating cooler (5), or the refrigerating cooler ( Depending on the combined flow rate with the refrigerant sucked from 4), it will change greatly.

  In general, the indoor temperature of the refrigerated space is +3 to 5 ° C., whereas the temperature of the refrigerated space is −18 to −20 ° C., so that the temperature difference from the outdoor temperature becomes large, which is necessary for cooling the frozen space. The refrigeration capacity is larger than the value required for the refrigeration space. Thus, when the refrigeration side refrigeration capacity is larger than the refrigeration side refrigeration capacity, that is, the load on the refrigeration side is set larger than the refrigeration side. In the freezing operation in this case, as shown in FIG. 7 schematically showing FIG. 6, a hatched area portion in the figure, which is an area having a large freezing capacity on the freezing side, is used.

  Therefore, as described above, the refrigeration capacity on the refrigeration side is not easily affected by the refrigerant returning from the refrigeration cooler (5), and thus the cooling control of the refrigeration space may be controlled by the rotational speed of the compressor (9). If the cooling is insufficient, as shown by the arrow, increase the number of rotations of the compressor (9) to increase the refrigeration power, and if it is excessively cooled, decrease or stop the number of rotations to properly adjust the cooling temperature. It can be held. The refrigeration side controls the cooling temperature by adjusting the flow rate of the refrigerant not by the rotation speed of the compressor (9) but by opening / closing control of the valve opening of the switching valve (11).

  One embodiment of the compressor rotation speed control according to 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 room (4) is compared with a predetermined target value (Fr), and the deviation is a PID controller (25 for determining the frequency of the compressor). ).

  If the temperature of the refrigeration space (2) is higher than the target value (Fr), the PID calculation value increases due to the deviation, and the refrigeration space (2) is cooled by increasing the rotational speed of the compressor (9) by a predetermined amount. Operation control is performed so as to promote and lead to a predetermined temperature. On the other hand, if the temperature of the refrigeration space (2) is lower than the target value (Fr), the rotational speed is decreased or stopped to decrease the refrigeration power.

  Next, another embodiment of the compressor rotation speed control according to the present invention will be described. Although the said Example controlled the rotation speed of the compressor (9) with the temperature information of freezing space (2), depending on the driving | running conditions of a refrigerator, it is refrigerated space (3) with respect to freezing space (2). ) Is also assumed to be insufficient.

  Therefore, if the temperature information of the refrigerated space (3) is input together with the temperature information of the refrigerated space (2) and the compressor (9) is operated in the hatched area in FIG. 7, the rotational speed of the compressor (9) is set. By increasing the raising refrigeration capacity, the refrigeration capacity of the refrigerated space (3) can be increased together with the refrigerated space (2).

  However, an increase in the rotational speed of the compressor (9) when the refrigerated space (2) is cooled to a target value or less will unnecessarily cool the refrigerated space (2) and consume wasteful power. Therefore, in the block diagram shown in FIG. 9, the refrigeration space temperature (Ra) and its target value (Rr) are input to the PID controller (25) together with the refrigeration space temperature (Fa) and its target value (Fr). When determining the rotational speed in (9), the deviation data value between the internal temperature (Fa) on the freezing space side and the target temperature (Fr) is input, for example, by adding twice, and the like. ) Is a larger amount of feedback of temperature information data on the freezing space (2) side.

  Thereby, the rotational speed of the compressor (9) is determined based on the refrigeration side based on the temperature information fed back on the refrigeration space (2) side, which is a deviation value that is considered to be larger than the actual value. When (2) is sufficiently cooled, refrigeration on the refrigeration side is performed by controlling the refrigerant flow to the refrigeration cooler (5) by the switching valve (11) without increasing the rotational speed of the compressor (9). The capacity is increased or decreased, and the refrigeration side is controlled to have an appropriate temperature without causing overcooling on the refrigeration side.

  In addition, although the said Example demonstrated what determined the rotation speed of a compressor (9) in consideration of the temperature information of refrigeration space (3), an external temperature should fall and refrigeration space (3) temperature by any chance. Is lower than the target value (Rr), the feedback signal reduces the rotational speed of the compressor (9), resulting in a problem that the refrigeration capacity on the refrigeration space (2) side is reduced. To do.

  FIG. 10 is a block diagram corresponding to such a case, in which a function (Fx) that feeds back temperature information only when the temperature of the refrigerated space (3) is higher than the target value (Rr) is inserted. Yes, if the difference between the refrigerated space temperature (Ra) and the target value (Rr) is small, the value is input, but if it is negative, a zero signal is input to the PID controller (25).

  By this control, even when the load of the refrigerated space (3) is light and the actual temperature (Ra) is lower than the target set value (Rr), the freezing space (2) has the target value (Fr) with the refrigerating power based on the temperature information. It is possible to prevent the temperature of the refrigeration space (2) from becoming higher than the target value (Fr) due to a decrease in the refrigeration power.

  Still another embodiment will be described. FIG. 11 shows the refrigeration capacity of the refrigeration cycle and the refrigeration cycle when the compressor (9) is driven at a certain rotational speed and the temperature of the refrigeration cooler (5) is changed under the condition that the condensation temperature is constant. This shows the change in QF1) (QR1).

  At this time, the refrigeration cooler (5) can reduce its refrigeration capacity (QR1) by lowering its surface temperature and increase its capacity by raising it. It can be seen that QF1) has a constant cooler temperature of, for example, -23.5 ° C, and is not significantly affected by fluctuations in the refrigeration capacity on the refrigeration side.

  And about the refrigerator (5) for refrigeration, if the rotation speed of the refrigeration fan (7) is changed, for example, if the rotation speed is lowered, the amount of heat exchange in the refrigeration cooler (5) will decrease, and the cooler As a result of the lowering of the surface temperature of (5), the refrigeration capacity (QR1) of the refrigeration cycle also decreases, and conversely, if the rotational speed of the fan (7) is increased, the amount of heat exchange increases and the cooler (5 ) And the cycle refrigerating capacity (QR1) increases.

  That is, with regard to the cooling control of the refrigerated space (3), the space temperature can be controlled by increasing or decreasing the rotational speed of the refrigeration fan (7), and the refrigerated space temperature (Ra) is more than the target value (Rr). If it is high, it can be cooled by increasing the number of revolutions of the refrigeration side cooling fan (7), and if it is undercooled below the target value (Rr), the cooling power is reduced by decreasing the number of revolutions of the fan to achieve a predetermined optimum temperature. Can be controlled.

  FIG. 12 shows changes in the refrigeration capacity (QF2) (QR2) of the refrigeration and refrigeration cycles when the temperature of the refrigeration cooler (4) is changed. ) Is reduced, the refrigerant circulation amount sucked into the lower stage side of the compressor (9) through the refrigeration cooler (4) is reduced, and the capacity (QF2) of the refrigeration side cycle is reduced. Further, since the amount of refrigerant sent from the lower stage side of the compressor (9) to the higher stage compression section is also reduced, the refrigeration cooler (5) is changed from the refrigeration cooler (5) to the intermediate pressure section because of the excluded volume of the higher stage compression section. The amount of refrigerant sucked into the return higher stage compression section will increase, and the refrigeration capacity (QR2) of the refrigeration side cycle will increase.

  Therefore, when the temperature of the refrigerated space (3) is higher than the target value (Rr) and the cooling is insufficient, or when the refrigeration capacity of the refrigerated space (2) is excessive, the refrigeration side cooling fan (6) The cycle capacity (QR2) on the refrigeration side is increased or the refrigeration side is reduced by reducing the surface temperature of the cooler (4) by reducing the heat exchange amount in the cooler for freezing (4) The cycle capacity (QF2) can be reduced and each cooling space can be controlled to an appropriate temperature.

  As described above, since the refrigerating space (2) and the refrigerating space (3) can flow the refrigerant to the refrigerating cooler (5) simultaneously with the flow of the refrigerant to the refrigerating cooler (4), the evaporation temperature can be increased. Fluctuation in temperature in the refrigeration and refrigeration spaces due to accurate refrigerant distribution by the refrigerant flow control switching valve (11), which consists of a three-way valve, even for temperature loads that can be cooled well and are introduced to each storage space as needed Thus, each space temperature can be controlled appropriately.

  In the refrigeration cycle described above, the refrigerant flow to the refrigeration and refrigeration coolers (4) and (5) can be controlled to flow at the same time. The refrigerant is not biased to the cooler, 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-based refrigerant is employed, the amount of refrigerant charged can be reduced, and safety is improved.

  The two-stage compressor (9) in the above embodiment has been described with the pressure in the compressor case (9c) being an intermediate pressure. However, the invention is not limited to this. The suction pipe from the cooler is communicated with the space inside the compressor case, and the suction pipe from the refrigeration cooler is connected to the connection part between the discharge port of the low-stage compression unit and the suction port of the high-stage compression unit. It may be. Similarly, as a high-pressure case, the suction pipe from the refrigeration cooler is connected to the suction port of the low-stage compression unit, and the suction pipe from the refrigeration cooler is connected to the discharge port of the low-stage compression unit and the high stage. You may make it connect to the connection part with the suction inlet of a side compression part, and may discharge the discharge gas from a high stage side compression part from the inside of a high pressure case to the discharge pipe to a condenser.

  ADVANTAGE OF THE INVENTION According to this invention, it can utilize for the refrigerator which improved cycle efficiency with the two-stage compression type refrigerating cycle structure.

It is a refrigerating cycle diagram of a refrigerator showing one embodiment of the present invention. It is a schematic longitudinal cross-sectional view of the refrigerator carrying the refrigeration cycle of FIG. It is a longitudinal cross-sectional view which shows the detail of the two-stage compressor in FIG. It is a top view which shows the detail of the principal part of the three-way valve in FIG. It is a block diagram which shows the other Example of a refrigerating cycle. It is a graph of the relationship between the refrigeration and refrigeration side refrigeration capacity and the refrigerant flow. It is a schematic diagram of FIG. It is a block diagram of compressor rotation speed control. It is a rotational speed control block diagram which added the refrigeration temperature information to the control of FIG. FIG. 10 is a rotation speed control block diagram obtained by further improving the control of FIG. 9. It is explanatory drawing which shows the change of freezing at the time of changing the cooler temperature for refrigeration of this invention, and refrigeration freezing capacity. It is explanatory drawing which shows the change of freezing and refrigeration freezing ability at the time of changing the cooler temperature for freezing of this invention. It is a freezing cycle figure of the conventional refrigerator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Refrigerator main body 2 Refrigeration space 3 Refrigeration space 4 Refrigeration cooler 5 Refrigeration cooler 6, 7 Cooling fan 8 Machine room 9 Two stage compressor 9a Low stage compression part 9b High stage compression part 9c Case 10 Condenser
11 Switching valve 12 Refrigeration capillary 13 Refrigeration capillary
14 Accumulator 15 Refrigeration side suction pipe 16 Discharge pipe
17, 24 Refrigeration side suction pipe 18 Valve case 19 Valve seat
19a Refrigeration side valve port A 19b Refrigeration side valve port B 20 Valve body
20a Refrigeration side groove A 20b Refrigeration side groove B 20c Rotating shaft
20d Thick stepped portion 21 Inlet valve port 22 Side pipe
23 Gas-liquid separator 25 PID controller

Claims (5)

  A compressor with variable capacity driven by an inverter, in which the compression element is composed of a low-stage compression section and a high-stage compression section, and a refrigerant flow path provided on the outlet side of the condenser that receives the discharge gas from the compressor In a refrigerator in which a refrigeration cycle is formed from a switching valve that controls the flow rate, and a refrigeration cooler and a refrigeration cooler that are connected to the switching valve via a decompression device, the compression is performed according to the refrigeration space temperature and its target value. A refrigerator characterized by determining the number of rotations of the machine.   A compressor with variable capacity driven by an inverter, in which the compression element is composed of a low-stage compression section and a high-stage compression section, and a refrigerant flow path provided on the outlet side of the condenser that receives the discharge gas from the compressor In a refrigerator in which a refrigeration cycle is formed from a switching valve for controlling a flow rate, and a refrigeration cooler and a refrigeration cooler connected to the switching valve via a decompression device, respectively, the refrigeration space together with the refrigeration space temperature and its target value A refrigerator that determines the number of rotations of a compressor based on a temperature and a target value thereof, wherein the amount of feedback of temperature information on the refrigeration space side is larger than that in a refrigerated space when the number of rotations is determined.   3. The refrigerator according to claim 2, wherein the temperature information is used for determining the compressor speed only when the temperature of the refrigerated space is higher than the target value.   The refrigerator according to any one of claims 1 to 3, wherein when the refrigerated space temperature is higher than the target value, the number of rotations of the refrigeration side cooling fan is increased. The refrigerator according to any one of claims 1 to 4, wherein when the temperature of the refrigerated space is higher than the target value, the rotational speed of the refrigeration side cooling fan is decreased.

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