JP2009036502A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve defrosting capacity in a heating cycle, and to improve defrosting finish determining accuracy. <P>SOLUTION: A refrigerating cycle has a compressor 1, a four-way valve 8, an indoor heat exchanger 3, a pressure reducer 4 and an outdoor heat exchanger 5, and has a first bypass circuit 18 connecting a part between the outdoor heat exchanger 5 and the pressure reducer 4 and a part between the compressor 1 and a delivery pipe 2, and a second bypass circuit 19 connecting the delivery pipe 2 of the compressor 1 to a suction part of the compressor 1, and is constituted by arranging an opening-closing mechanism 7 in the first and second bypass circuits 18 and 19. Heating defrosting operation can melt frost by raising the refrigerant temperature and pressure of the outdoor heat exchanger 5, without sending cold air into a room, by putting the pressure reducer 4 in a blocked-up state, by changing the four-way valve 8 to a cooling operation cycle from the heating cycle, after performing defrosting operation of the heating cycle up to a predetermined condition. The pressure reducer 4 is opened in predetermined opening, and the defrosting finish determining accuracy can be improved by circulating a refrigerant a little to the indoor heat exchanger 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an air conditioner capable of improving the defrosting capability and improving the accuracy of defrosting end determination control in a defrosting cycle that enables a defrosting operation in a heating cycle.

  Conventionally, in the case of a refrigeration cycle that performs heating operation of an air conditioner, a four-way valve circulates a high-temperature high-pressure refrigerant discharged from a compressor to an indoor heat exchanger, and the refrigerant is condensed into a high-pressure liquid refrigerant. This refrigerant flows to the outdoor expansion valve and adiabatically expands to a low-temperature low-pressure refrigerant, and then absorbs heat from outdoor air in the outdoor heat exchanger and returns to the compressor as a gaseous low-pressure refrigerant through the accumulator. At this time, when the outdoor air temperature is low, such as below freezing, moisture in the air forms frost on the outdoor heat exchanger. The frosted heat exchanger has extremely low heat exchange capacity and cannot sufficiently obtain heating capacity, so it is necessary to melt it. At this time, in the conventional air conditioner, the four-way valve is reversed from the heating operation to the cooling cycle, the indoor fan and the outdoor fan are stopped, the high-temperature and high-pressure refrigerant is circulated in the outdoor heat exchanger, and the frost attached to the heat exchanger The method of melting ice and ice was common.

  Therefore, as a defrosting method that does not require switching of the four-way valve, there is an air conditioner that performs the defrosting operation by bypassing the discharge gas while maintaining the heating cycle during the heating operation, in which case the defrosting operation ends. The heating cycle is maintained up to (for example, see Patent Document 1).

FIG. 3 shows a conventional air conditioner described in Patent Document 1. As shown in FIG. As shown in FIG. 3, the compressor 1, the discharge pipe 2, the indoor heat exchanger 3, the electric expansion valve 4, the liquid pipe 15, the outdoor heat exchanger 5, the accumulator 6, and the bypass circuit 16. And the on-off valve 17. In the above configuration, when the defrosting operation is performed during the heating operation, the four-way valve 8 maintains the heating cycle as it is, the outdoor expansion valve 4 is fully opened, the outdoor fan 14 is stopped, the indoor fan 13 is operated with low wind, and the bypass circuit 16 The release valve 17 is opened so that the discharge gas flows through the bypass circuit. By doing so, the indoor heating operation can be continued and the four-way valve 8 is not switched, so that problems such as running out of oil can be avoided.
Japanese Patent Laid-Open No. 2-17370

  However, in the configuration of switching to the cooling cycle during the conventional defrosting operation, the room temperature is lowered to temporarily stop the heating operation, and the four-way valve is reversed to generate refrigerant noise, run out of the compressor 1 oil, It had problems such as liquid return.

  In addition, in the configuration in which the heating cycle is performed even during the defrosting operation, the refrigerant circulating in the outdoor heat exchanger is a refrigerant whose pressure has dropped, and the temperature of the outdoor heat exchanger cannot sufficiently rise, resulting in unmelted frost. Or has a problem that it is difficult to determine the end of defrosting.

  This invention solves the said conventional subject, and it aims at providing the air conditioner which prevents the unmelted frost to an outdoor heat exchanger and can improve the precision of a defrost end determination. .

In order to solve the conventional problems, an air conditioner according to the present invention includes a compressor, a four-way valve, an indoor heat exchanger, a decompressor, and an outdoor heat exchanger connected by a refrigerant pipe, and the outdoor heat exchanger and the A first bypass circuit that connects between the pressure reducer and the compressor discharge pipe; and a second bypass circuit that connects the compressor discharge pipe and the compressor suction portion. In the refrigeration cycle provided with an open / close mechanism in the bypass circuit, the heating defrosting operation is changed from the state in which the four-way valve is in the heating cycle to the cooling cycle after the heating cycle defrosting operation is performed up to a predetermined condition. The open / close mechanism on the bypass circuit is left open, and the pressure reducer is closed or substantially closed.

  As a result, the refrigerant is not circulated through the indoor heat exchanger, and even if the four-way valve is in the cooling cycle, the cold air is not sent into the room, the refrigerant pressure in the outdoor heat exchanger is increased, and heat exchange is performed. The frost can be melted by raising the vessel temperature.

  Moreover, the air conditioner of this invention opens the said decompressor to predetermined opening degree after being mentioned above, and circulates a refrigerant | coolant to an indoor heat exchanger slightly. As a result, the refrigerant circulates from the outdoor heat exchanger to the indoor heat exchanger, so that the pipe temperature sensor arranged for detecting the outdoor heat exchanger temperature can detect the accurate temperature of the outdoor heat exchanger. Thus, it is possible to determine the completion of defrosting with higher accuracy.

  The air conditioner of the present invention can prevent the frost from remaining in the outdoor heat exchanger during the defrosting operation in the heating operation, or can accurately determine the end of the defrosting.

  In the first aspect of the invention, the heating / defrosting operation is changed from the state where the four-way valve is in the heating cycle to the cooling operation cycle after the heating cycle defrosting operation is performed to a predetermined condition, and the opening / closing on the bypass circuit is performed. The mechanism remains open and the decompressor is closed or in a substantially closed state, thereby increasing the refrigerant pressure in the outdoor heat exchanger and increasing the heat exchanger temperature to thaw frost. it can.

  In the second invention, in particular, in the first invention, when a predetermined time has elapsed after starting the heating defrosting operation, or the detection temperature of the pipe temperature sensor attached to the outdoor heat exchanger is predetermined. When the temperature exceeds a predetermined temperature, the decompressor is set to a predetermined opening degree, the refrigerant is circulated to the indoor heat exchanger, and then the end of the defrosting is determined based on the temperature detected by the piping temperature sensor of the outdoor heat exchanger. Thus, it is possible to accurately determine the end of defrosting.

  In the third aspect of the invention, in particular, the refrigeration cycle can be optimized by making the opening / closing mechanism of the bypass circuit of the first or second aspect of the invention an expansion valve that can be fully closed.

  In the fourth aspect of the invention, in particular, the manufacturing cost can be reduced by using an electromagnetic two-way valve as the opening / closing mechanism of the bypass circuit of the first or second aspect of the invention.

  In the fifth aspect of the invention, in particular, the refrigeration cycle can be optimized by using the decompressor of the first or second aspect of the invention as an expansion valve that can be fully closed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a refrigeration cycle diagram of an air conditioner according to a first embodiment of the present invention. In FIG. 1, the refrigeration cycle includes a compressor 1, an indoor heat exchanger 3, an expansion valve 4 that can be fully closed as a decompressor, an outdoor heat exchanger 5, and a four-way valve 8 connected by refrigerant piping. Further, a bypass circuit A is provided from the discharge pipe 2 of the compressor 1 to a connecting pipe 4a between the outdoor heat exchanger 5 and the expansion valve 4, and an electromagnetic two-way valve 7, a capillary tube 9A, and a check valve are provided in the middle. 10A is arranged. Further, a bypass circuit B is provided between the electromagnetic two-way valve 7 and the capillary tube 9 </ b> A and between the accumulator 6. A capillary tube 9B and a check valve 10B are also arranged in the bypass circuit B.

  In the above configuration, when the outdoor expansion valve 4 is opened to a predetermined opening while the four-way valve 8 remains in the heating cycle, the high-temperature and high-pressure refrigerant in the indoor heat exchanger 3 is in a gas-liquid two-phase weak and high temperature state (+ 5 ° C. to 10 ° C. It flows into the outdoor heat exchanger 5 that has been frosted. Frost and ice adhering to the outdoor heat exchanger 5 are melted by this high-temperature refrigerant. However, at this time, the refrigerant flowing in the gas-liquid two-phase is a mechanism that dissipates heat when the gas component is liquefied, so that the liquid refrigerant component increases as it circulates through the heat exchanger, and the liquid component returns to the compressor 1 when it returns. Will occupy the majority. For this reason, there existed a subject of impairing reliability, such as the liquid return phenomenon of the compressor 1, and insufficient discharge superheat (heating degree) by the fall of discharge temperature. Moreover, when the discharge temperature decreases, the dryness of the refrigerant circulating from the outdoor expansion valve 4 to the outdoor heat exchanger 5 also decreases, and the defrosting ability of the outdoor heat exchanger 5 for melting frost and ice also decreases. End up.

  Therefore, by bypassing the discharge gas of the compressor 1 between the outdoor expansion valve 4 and the outdoor heat exchanger 5, the temperature and pressure of the refrigerant circulating in the outdoor heat exchanger 5 are increased, and the defrosting capability is improved. . At the same time, the discharge gas is branched after passing through the electromagnetic two-way valve 7 and flows into the compressor 1 intake. By doing so, it is possible to maintain the dryness of the compressor intake gas and prevent the above-described reliability problems and the decrease in the discharge temperature.

  There are two major problems in defrosting by such a cycle. One is that the temperature of the outdoor heat exchanger 5 does not rise sufficiently, and the case where the defrosting capacity is insufficient is generated. Another is that it is difficult to distinguish when the frost has melted and when it has not melted.

  First, when a predetermined condition is satisfied while performing the defrosting operation in the heating cycle as described above, in the embodiment of the present invention, the detected temperature of the pipe temperature sensor B12 attached to the outdoor heat exchanger 5 is: When a state exceeding a predetermined temperature (for example, 8 ° C.) continues for a predetermined time (for example, 1 minute), or when the maximum time (for example, 10 minutes) is exceeded, the end of defrosting is determined. Includes the case where the defrosting is not completely completed.

  Therefore, after the defrosting operation of the heating cycle is completed, the outdoor four-way valve 8 is reversed to perform the cooling cycle defrosting operation. The refrigeration cycle at this time is shown in FIG. By doing so, the high-temperature and high-pressure gas refrigerant discharged from the compressor 1 circulates through the outdoor heat exchanger 5 in the direction opposite to that during the heating cycle defrosting. That is, the hottest refrigerant flows into the portion that is the most difficult to defrost at the time of defrosting the heating cycle, and the defrosting ability can be improved. At this time, since the electromagnetic two-way valve 7 on the bypass remains open, even if the compressor 1 is not stopped, the pressure difference is sufficiently small, so that the refrigerant noise caused by switching the four-way valve 8 is minimized. be able to. Further, the oil of the compressor 1 is not in a state where it is insufficient.

  At this time, the outdoor expansion valve 4 may be fully closed or may be slightly opened. The reason for fully closing is to prevent the low-temperature and low-pressure refrigerant from completely flowing into the room, which has the advantage of completely shielding the refrigerant sound and avoiding cold air in the room. Since the refrigerant accumulates in 5, it cannot be operated continuously for a long time. Further, since the refrigerant does not circulate in this state, it is difficult to determine whether or not the outdoor heat exchanger 5 has been completely defrosted. In contrast, when the air is slightly opened, the refrigerant circulates in the room, so that there are problems of refrigerant sound and cold air. However, even in this case, long-time operation is difficult.

Thereafter, in the embodiment of the present invention, the outdoor expansion valve 4 is opened by a certain degree of opening in order to perform the defrosting determination. By doing so, the outdoor heat exchanger 5 becomes a high pressure side, and if the frost is completely melted, 10 ° C.
As described above, if it is not melted, it is about 0 ° C. to 4 ° C., and therefore it is possible to sufficiently determine the defrosting end even if the variation of the pipe temperature sensor is taken into consideration. If it is determined that the defrosting has not ended, the four-way valve 8 is switched and the electromagnetic two-way valve 7 on the bypass circuit is also returned to the closed state to perform the cooling cycle defrosting. The pipe temperature sensor used at this time is the pipe temperature sensor A11 that becomes the outlet of the heat exchanger. Further, since the determination can be made in a short time (for example, 30 seconds), there is no problem in the room.

FIG. 2 shows an actual control flow using the refrigeration cycle configured as described above. In FIG. 2, the defrosting determination is performed during the heating operation, and the defrosting operation is started (S1). And if the detected temperature of the outdoor piping temperature sensor B12 is a lapse of a predetermined temperature t ₁ or more and consisting or a predetermined time T1 (S2), switches the four-way valve 8 to the cooling cycle (S3). By doing so, the direction of the refrigerant flowing through the outdoor heat exchanger 5 is reversed. In the defrosting operation of the heating cycle, since the high-temperature discharged refrigerant flows into the outlet side where it becomes the outlet side and frost is not easily melted, effective defrosting is possible. At this time, the expansion valve 4 is completely closed (S4), and no refrigerant flows into the room. Then when the temperature of the outdoor piping temperature sensor A11 is that the lapse of a predetermined value t ₂ or more and composed or the predetermined time T2 (S5), an expansion valve and the degree through which predetermined opening (slightly refrigerant, for example, the present invention 80 pulses) (S6), and the refrigerant is slightly circulated indoors. By doing so, it is possible to accurately determine whether the refrigerant circulates in the outdoor heat exchanger 5 and whether the heat exchanger is melted by the temperature detected by the pipe temperature sensor A11 (S7). If when the detected temperature of the outdoor piping temperature sensor A11 was the predetermined temperature t ₃ or more, it is returned directly to the heating operation (S8). Otherwise, it is determined that there is unmelted, and the defrosting operation is performed in which the four-way valve 8 is switched to the cooling cycle and the electromagnetic two-way valve 7 of the bypass circuit is closed (S9).

  As described above, in the present embodiment, the four-way valve 8 is reversed during the defrosting operation in the heating cycle so that the cooling cycle is performed, so that problems such as refrigerant noise and generation of cold air in the room can be avoided. The defrosting capability of the heat exchanger 5 can be improved, and the accuracy of the defrost determination control can be improved.

  In addition, by making the electromagnetic two-way valve 7 on the bypass of the present embodiment an expansion valve that can be fully closed, the capillary tube 9 is not particularly necessary, the cost can be reduced, and the refrigeration cycle can be optimized. It can be performed. Moreover, the manufacturing cost can be reduced by using an electromagnetic two-way valve as the bypass circuit opening / closing mechanism. In addition, the refrigeration cycle can be optimized by using an expansion valve that can be fully closed.

  As described above, the defrosting operation control according to the present invention can improve the defrosting capability and improve the defrosting determination accuracy without impairing the reliability of the refrigeration cycle.

Refrigeration cycle diagram of the air conditioner in Embodiment 1 of the present invention Control flow diagram in Embodiment 1 of the present invention Refrigeration cycle diagram of a conventional air conditioner

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Discharge pipe 3 Indoor heat exchanger 4 Expansion valve 4a Connection piping 5 Outdoor heat exchanger 6 Accumulator 7 Electromagnetic two-way valve 8 Four-way valve 9 Capillary tube 10 Reverse branch valve 11 Outdoor piping temperature sensor A
12 Outdoor piping temperature sensor B
DESCRIPTION OF SYMBOLS 13 Indoor fan 14 Outdoor fan 15 Liquid pipe 16 Bypass circuit 17 On-off valve 18 1st bypass circuit 19 2nd bypass circuit

Claims (5)

A compressor, a four-way valve, an indoor heat exchanger, a decompressor, and an outdoor heat exchanger are connected by a refrigerant pipe, and a first part that connects between the outdoor heat exchanger and the decompressor and between the compressor discharge pipes. And a second bypass circuit for connecting the compressor discharge pipe and the compressor suction section, and the first and second bypass circuits are provided with an opening / closing mechanism, in a heating defrosting operation After the defrosting operation of the heating cycle is performed to a predetermined condition, the four-way valve is set to a cooling operation cycle, the opening / closing mechanism on the bypass circuit is opened, and the pressure reducer is closed or substantially closed. An air conditioner characterized by the above. When the specified time has elapsed after the start of the heating defrosting operation, or when the temperature detected by the pipe temperature sensor attached to the outdoor heat exchanger exceeds a predetermined temperature, the decompressor 2. The air conditioner according to claim 1, wherein the refrigerant is circulated to the indoor heat exchanger at a predetermined opening degree, and then the end of the defrosting is determined based on a temperature detected by a pipe temperature sensor of the outdoor heat exchanger. . The air conditioner according to claim 1 or 2, wherein an expansion valve that can be fully closed is disposed in an opening / closing mechanism of the first and second bypass circuits. The air conditioner according to claim 1 or 2, wherein an electromagnetic two-way valve is disposed in the opening and closing mechanism of the first and second bypass circuits. The air conditioner according to claim 1 or 2, wherein an expansion valve that can be fully closed is disposed in the decompressor.