JP2007178106A - Cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce frequent starts and stops of a compressor by improving control of a defrosting operation. <P>SOLUTION: This cooling device 1 has a refrigerating cycle configurated by connecting an outdoor unit 2 having the compressor 6 and an outdoor heat exchanger 7 and an indoor unit 3 having an electronic expansion valve 9 and an indoor heat exchanger 10, to piping for circulating a refrigerant, and comprises an off-cycle defrosting control means performing a defrosting operation of the indoor heat exchanger 10 by stopping the compressor 6 on the basis of a refrigerant temperature of the indoor heat exchanger 10. The off-cycle defrosting control means 18 performs the defrosting operation under a condition that a run length of the compressor after starting the cooling operation or after the execution of last defrosting operation is over a first reference value, or an integrated operation time of the compressor is over a second reference value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling device, and more particularly to a cooling device having an off-cycle defrosting function for performing a defrosting operation on an indoor heat exchanger.

  The cooling device connects an outdoor unit equipped with a compressor, an outdoor heat exchanger, etc., and an indoor unit equipped with an electronic expansion valve, an indoor heat exchanger, etc. by piping, and forms a refrigeration cycle by circulating refrigerant. is doing. As such a cooling device, a cooling device having an off-cycle defrosting control function for performing a defrosting operation on an indoor heat exchanger during a cooling operation is known. Off-cycle defrost control is a defrosting operation of the indoor heat exchanger by stopping the compressor and rotating the indoor fan in a predetermined mode when the refrigerant temperature of the indoor heat exchanger has decreased to a predetermined temperature. I do. Further, when the defrosting operation is activated, the compressor is stopped for a predetermined time (for example, 3 minutes), and then when the refrigerant temperature of the indoor heat exchanger rises to a predetermined temperature (for example, 12 ° C.), the compressor is restarted. Start the cooling operation. In this way, by repeating the stop and start of the compressor under the defined conditions, the moisture contained in the indoor air becomes frost and adheres to the piping of the indoor heat exchanger while performing the cooling operation. To prevent that.

  Moreover, in patent document 1, in order to suppress the frequent start / stop of a compressor, the frequency | count of the frequency | count that the compressor stopped was counted, and the reference | standard of the temperature of the indoor heat exchanger which restarts a compressor based on the count value It is described that the value is changed. That is, if the number of stoppages of the compressor increases, the reference value of the temperature of the indoor heat exchanger that restarts the compressor is changed to a high value, making it difficult to restart the compressor. According to this, frequent start / stop of the compressor can be suppressed.

JP 2000-297958 A

  However, the technique described in Patent Document 1 may not sufficiently suppress frequent start / stop of the compressor. That is, conditions for restarting the compressor are taken into account, but conditions for stopping the compressor are not taken into consideration. For example, the refrigerant temperature of the indoor heat exchanger may suddenly drop temporarily when the compressor is started. In spite of such a temporary decrease in the refrigerant temperature, the defrosting operation is activated, and the compressor that is originally unnecessary may be frequently started and stopped.

  An object of the present invention is to improve the control of the defrosting operation and suppress frequent start / stop of the compressor.

  In order to solve the above-mentioned problems, the cooling device of the present invention connects an outdoor unit having a compressor and an outdoor heat exchanger and an indoor unit having an electronic expansion valve and an indoor heat exchanger to piping for circulating the refrigerant. In a cooling device comprising an off-cycle defrost control means for forming a refrigeration cycle and stopping the compressor based on the refrigerant temperature of the indoor heat exchanger to defrost the indoor heat exchanger. The frost control means determines that the continuous operation time of the compressor after the start of the cooling operation or the execution of the previous defrosting operation exceeds the first reference value, and the cumulative operation time of the compressor exceeds the second reference value. The defrosting operation is performed under any one of the above conditions.

  That is, the refrigerant temperature of the indoor heat exchanger decreases rapidly immediately after the compressor starts, and then gradually increases and stabilizes at a constant temperature. Therefore, the defrosting operation is not operated until the refrigerant temperature is stabilized. Like that. That is, until the refrigerant temperature of the indoor heat exchanger is stabilized, the defrosting operation does not operate even if the refrigerant temperature satisfies the condition temperature for starting the defrosting operation. The operation can be suppressed. Thereby, frequent start / stop of the compressor can be suppressed.

  In this case, the off-cycle defrosting control unit includes a reference value setting unit that sets the first reference value and the second reference value based on the indoor set temperature, and the reference value setting unit has an indoor set temperature of It is desirable to set the first reference value and the second reference value larger as the value becomes lower. According to this, for example, in a cooling device for a low-temperature warehouse, since the indoor set temperature is low, a rapid decrease in the refrigerant temperature immediately after starting the compressor is likely to occur, and the time required for the temperature to stabilize becomes longer. Correspondingly, the first reference value and the second reference value, which are conditions for operating the defrosting operation, can be increased. Therefore, in response to various environments with different indoor set temperatures, it is possible to stably suppress the operation of the defrosting operation which is originally unnecessary, and to suppress frequent start / stop of the compressor.

  Moreover, it is desirable that the reference value setting means sets the first reference value and the second reference value based on the indoor set temperature every time the compressor is started. According to this, for example, even if the indoor set temperature is changed during the cooling operation, the first reference value which is a condition for operating the defrosting operation corresponding to the indoor set temperature every time the compressor is started. And the second reference value can be changed. Therefore, the operation | movement of the defrost operation which is originally unnecessary can be suppressed stably, and the frequent start / stop of a compressor can be suppressed. In this case, the setting change of the first reference value and the second reference value can be performed every preset time instead of being performed every time the above-described compressor is started.

  ADVANTAGE OF THE INVENTION According to this invention, the control of a defrost operation can be improved and the frequent start / stop of a compressor can be suppressed.

  Hereinafter, an embodiment of a cooling device to which the present invention is applied will be described with reference to FIGS. In addition, this embodiment illustrates the case where this invention is applied to the cooling device for low temperature warehouses. FIG. 1 is a diagram showing the configuration of the cooling device of the present embodiment. As shown in FIG. 1, the cooling device 1 includes an outdoor unit 2, an indoor unit 3, and a gas side connection pipe 4 and a liquid side connection pipe 5 that connect these in an annular shape.

  The outdoor unit 2 includes a compressor 6, an outdoor heat exchanger 7, and an outdoor pipe 8 that connects the gas side connection pipe 4 and the liquid side connection pipe 5 to circulate the refrigerant.

  The indoor unit 3 includes an electronic expansion valve 9, an indoor heat exchanger 10, and an indoor pipe 11 that connects the gas side connection pipe 4 and the liquid side connection pipe 5 to circulate the refrigerant. In addition, an indoor fan 12 that blows indoor air to the indoor heat exchanger 10 is provided in the vicinity of the indoor heat exchanger 10, and the pipes on the inlet side and the outlet side of the indoor heat exchanger 10 are respectively provided with liquids. A side refrigerant temperature sensor 13 and a gas side refrigerant temperature sensor 14 are provided. Furthermore, the indoor unit 3 is provided with an indoor temperature sensor 16 that detects the indoor temperature, an indoor set temperature holder 17 that holds the indoor set temperature, and an off-cycle defrost control device 18. The off-cycle defrost control device 18 is connected to the compressor 6, the indoor fan 12, the liquid side refrigerant temperature sensor 13, the gas side refrigerant temperature sensor 14, the indoor temperature sensor 16, and the indoor set temperature holder 17 through signal lines. Has been.

  Next, the details of the off-cycle defrost control device 18 which is a characteristic part of the present invention will be described with reference to FIGS. FIG. 2 is a diagram illustrating an internal configuration of the off-cycle defrost control device 18. As shown in FIG. 2, the off-cycle defrost control device 18 includes a reference value table 22 that stores reference values T1 to T8 necessary for off-cycle defrost control, and after the start of the cooling operation or after the previous defrost operation. The continuous time counter 23 and the accumulated time counter 24 for storing the continuous operation time and the accumulated operation time of the compressor of FIG. The arithmetic processing unit 25 updates the values stored in the continuous time counter 23 and the integrated operation time counter 24 based on the operation status information of the compressor 6. Further, the reference values T1 and T2 of the reference value table 22 are updated based on the indoor set temperature held by the indoor set temperature holder 17. In addition to the above-described operation status information and indoor set temperature, the refrigerant temperature on the inlet side of the indoor heat exchanger 10 measured by the liquid side refrigerant temperature sensor 13 and the indoor heat exchanger measured by the gas side refrigerant temperature sensor 14 10 refrigerant temperature at the outlet side, room temperature measured by the room temperature sensor 16, values stored in the reference value table 22, values stored in the continuous time counter 23 and the integrated operation time counter 24, etc. Based on these pieces of information, an operation / stop control command for the compressor 6 and a rotation speed control command for the indoor fan 12 are output.

  FIG. 3 is a flowchart showing the off-cycle defrosting control operation performed by the off-cycle arithmetic processing unit 25. When a cooling operation start switch (not shown) is operated, the compressor 6 is started and the cooling operation is started. Based on the indoor set temperature held by the indoor set temperature holder 17, the reference times T1 and T2 (minutes) are automatically set (S0). Here, as shown in FIG. 4, the values of the reference times T1 and T2 become larger as the indoor set temperature becomes lower, and are set while maintaining the relationship of T1 <T2. More specifically, T1 should not be a short time such as 1 to 10 minutes when the refrigerant temperature of the indoor heat exchanger suddenly decreases and is not stable after the compressor 6 is started. For example, it is set to 15 minutes when the refrigerant temperature is stabilized. T2 is set to a larger value, for example, 30 minutes. In addition, appropriate values are set in advance for the reference values T3 to T8 used in the following processing.

  Next, it is determined whether the continuous operation time or the accumulated operation time of the compressor 6 has passed the reference time T1 or T2 (minutes), respectively (S1). If neither the continuous operation time nor the accumulated operation time has passed the reference time, the cooling operation is continued and the process returns to S0. When the reference time has elapsed in either one, it is determined whether or not the refrigerant temperature on the liquid side or gas side of the indoor heat exchanger 10 is lower than the reference temperature T3 (° C.) (S2). Here, the reference temperature T3 is preferably about 0 ° C. The process of S2 is repeated until one of the refrigerant temperature on the liquid side or the gas side of the indoor heat exchanger 10 becomes lower than the reference temperature. When either one becomes lower than the reference temperature, it is determined whether or not the state is continuously maintained for the reference time T4 (min) (S3). S3 is a process for confirming whether or not the refrigerant temperature has stably decreased. The above-described S1 to S3 are the operating conditions of the defrosting operation according to the present embodiment. When the refrigerant temperature on the liquid side or the gas side of the indoor heat exchanger 10 does not keep the temperature below the reference temperature T3 (° C.) continuously for the reference time T4 (minutes), the process returns to S2. If held, based on the control command of the arithmetic processing unit 25, the air volume of the indoor fan 12 is switched to the set air volume for the defrosting operation (S4). Then, the compressor 6 is stopped (S5). That is, the defrosting operation is activated in this state. Here, the set air volume of the indoor fan 12 can also be set by an operation from a remote control switch (not shown).

  Next, it is determined whether or not the state where the defrosting operation is activated has passed the reference time T5 (minutes) (S6). That is, S6 considers that there is a possibility that the compressor 6 may be damaged by starting immediately after the compressor 6 is stopped, and the compressor 6 is forcibly stopped for T5 (minutes). It is a process for protection. The stop time T5 (min) may be about 3 minutes, for example. If the stop time of the compressor 6 has passed the reference time T5 (minutes), it is determined whether or not the refrigerant temperature on the liquid side or gas side of the indoor heat exchanger 10 is equal to or higher than the reference temperature T6 (° C.) (S7). T6 (° C.) is preferably set to about 10 ° C., for example. The process of S7 is repeated until either one of the refrigerant temperature on the liquid side or the gas side of the indoor heat exchanger 10 becomes equal to or higher than the reference temperature T6 (° C), and when either one becomes equal to or higher than T6 (° C), T6 (° C It is determined whether or not the refrigerant temperature on the other side that is less than the reference temperature T7 (° C.) or higher (S8). T7 (° C.) is desirably T3 (° C.) + 2 ° C. or higher, which is a condition for operating the defrosting operation, and is preferably about 4 ° C., for example. When the refrigerant temperature on the other side is lower than the base temperature T7 (° C.), the process returns to S7. When the refrigerant temperature on the other side becomes equal to or higher than the reference temperature T7 (° C.), it is determined whether or not the room temperature is equal to or higher than the indoor set temperature + T8 (° C.) (S9). S9 is a process provided to suppress the power consumption of the cooling device 1. That is, power consumption can be suppressed by keeping the compressor 6 stopped until the room temperature rises to the indoor set temperature + T8 ° C. In addition, T8 can be set to a large value when it is desired to promote suppression of power consumption, and can be set to 0 ° C. when it is desired to strictly manage the room temperature with respect to the indoor set temperature. If the room temperature is less than the room set temperature + T8 (° C.), the process returns to S7. When the room temperature becomes equal to or higher than the room set temperature + T8, the cooling operation is resumed and the process returns to S0 again. S7-S9 mentioned above becomes the cancellation | release conditions of the defrost operation in this invention.

  According to the off-cycle defrost control as described above, for example, even if the refrigerant temperature of the indoor heat exchanger 10 temporarily decreases when the compressor 6 is started, the compressor 6 is continuously operated by the process of S1. The defrosting operation does not operate unless the operation time or the accumulated operation time has passed the reference time T1 or T2. Thereby, since the compressor 6 continues the cooling operation without stopping, frequent start / stop of the compressor can be suppressed. Further, depending on the indoor set temperature, the time required for the refrigerant temperature of the indoor heat exchanger 10 to decrease and the refrigerant temperature to stabilize at the start of the compressor 6 changes. Since the value of T2 is set, it is possible to stably suppress frequent start / stop of the compressor corresponding to various environments having different indoor set temperatures.

  In addition, although this embodiment illustrated the case where this invention is applied to the cooling device for low-temperature warehouses, it is not restricted to this, For example, T1-T8 is matched with a use also in defrost control, such as a personal air conditioner. Thus, the effects of the present invention can be achieved.

It is a figure which shows the structure of the cooling device of this embodiment. It is a figure which shows the internal structure of an off cycle defrost control apparatus. It is the figure which showed the operation | movement of off cycle defrost control with the flowchart. It is a figure which shows the relationship between indoor preset temperature and reference time T1, T2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cooling device 2 Outdoor unit 3 Indoor unit 4 Gas side connection piping 5 Liquid side connection piping 6 Compressor 7 Outdoor heat exchanger 8 Outdoor piping 9 Electronic expansion valve 10 Indoor heat exchanger 11 Indoor piping 13 Liquid side refrigerant temperature sensor 14 Gas Side refrigerant temperature sensor 17 Indoor set temperature retainer 18 Off-cycle defrost control device

Claims (5)

An indoor unit having a compressor and an outdoor heat exchanger and an indoor unit having an electronic expansion valve and an indoor heat exchanger are connected to a pipe for circulating the refrigerant to form a refrigeration cycle. In the cooling device comprising an off-cycle defrost control means for defrosting the indoor heat exchanger by stopping the compressor based on the refrigerant temperature of
The off-cycle defrosting control means determines that the continuous operation time of the compressor after the start of the cooling operation or after the previous execution of the defrosting operation has exceeded the first reference value, and the accumulated operation time of the compressor. The cooling device, wherein the defrosting operation is performed on the condition that either one of the second reference values is exceeded. 2. The cooling device according to claim 1, wherein the off-cycle defrosting control unit includes a reference value setting unit that sets the first reference value and the second reference value based on an indoor set temperature. . The cooling apparatus according to claim 2, wherein the reference value setting means sets the first reference value and the second reference value to be larger as the indoor set temperature is lower. 4. The cooling according to claim 3, wherein the reference value setting unit sets the first reference value and the second reference value based on the indoor set temperature every time the compressor is started. 5. apparatus. The cooling apparatus according to claim 3, wherein the reference value setting unit sets the first reference value and the second reference value based on the indoor set temperature for each set time.

Images