JPH04344084A - Operation control device for refrigerating apparatus - Google Patents

Abstract

PURPOSE:To improve the operational efficiency of a refrigerating apparatus during the defrosting operation period of a plurality of evaporators. CONSTITUTION:A plurality of sets of an evaporator 6 and an electric expansion valve 8 are connected in parallel in a refrigerant circuit 14 in order for the frosting condition to be detected by defrosting condition detecting means Th21 and Th22 from the temp. of each of the evaporators 6a and 6b. The defrosting operation is effected by a defrosting operation control means 51 according to the degree of the frosted condition of the evaporators 6a and 6b and, when the temp. of either of the evaporators before the defrosting operation reaches a frosting starting temp., the degree of opening of the electric expansion valve for the evaporator is reduced by a means 52 for reducing the opening degree before defrosting. In this way the amount of the frost deposited on each of the evaporators 6a and 6b immediately before start of the defrosting operation is made as uniform as possible to improve the operational efficiency. During the defrosting operation period, when the temp. of either of the evaporators reaches a frost thawing temp., the opening degree of the electric expansion valve for the evaporator is reduced by a means 53 for reducing the opening degree during defrosting. By this method, the amount of the refrigerant circulating in the other evaporator is increased to shorten the defrosting operation time.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a refrigeration system equipped with a plurality of evaporators, and more particularly to measures for improving defrosting operation efficiency.

0002

[Prior Art] Conventionally, for example, Japanese Patent Application Laid-Open No. 63-1800
As disclosed in Publication No. 50, in a refrigeration system in which a plurality of evaporators are connected in parallel in a refrigerant circuit, the opening degree of an electric expansion valve that reduces the pressure of liquid refrigerant supplied to each evaporator is determined by the evaporator. There is a known method that attempts to secure the capacity of each evaporator according to the required capacity while maintaining the refrigerant state appropriately by controlling the degree of superheating of the refrigerant at the outlet of the evaporator to converge to its control target value. It's technology.

Furthermore, as disclosed in, for example, Japanese Patent Laid-Open No. 2-78873, the frosting state of the evaporator is detected from the refrigerant state quantity related to the temperature of the evaporator, such as the suction pressure of the refrigerant circuit, and the evaporator is Operation of a refrigeration system that performs defrosting operation by introducing hot gas into the evaporator when frost forms, and when the frost on the evaporator melts, the defrosting operation ends and normal operation is resumed. The control device is a known technology.

0004

[Problem to be Solved by the Invention] By the way, in a refrigeration system equipped with a plurality of evaporators, if the latter of the above is applied, even when one evaporator becomes frosted, the other evaporators The container may not have frosted yet. That is, since frost formation mainly depends on the integration capacity during normal operation, the frost formation timing differs if the integration capacity of each evaporator differs.

[0005] In particular, even in an air conditioner in which a plurality of heat source side heat exchangers are incorporated into an outdoor unit and cold air is blown outdoors from each heat source side heat exchanger that serves as an evaporator during heating operation, Although the integral capacity of both heat source side heat exchangers should be approximately equal, the air flow of the fan may be biased due to the relationship with surrounding buildings. If there is a difference in the integral capacity between the heat exchangers on the heat source side due to such reasons, even if one heat exchanger on the heat source side forms frost, frost has not yet formed on the other heat exchangers on the heat source side. . Therefore, if you start defrosting operation as it is, the operating efficiency of the entire refrigeration system will deteriorate, but if you continue normal operation until other heat source side heat exchangers also frost, the heat source side heat exchanger that has frosted first will There was a risk that excessive frost would form on the container, impairing its reliability, or that the defrosting operation time would become too long, thereby sacrificing the functionality of the refrigeration equipment, such as air conditioning.

[0006] The present invention has been made in view of the above-mentioned points, and its object is to control the frosting of each evaporator according to the frosting state of each evaporator before or during defrosting operation. By taking measures to appropriately control the opening degree of the electric expansion valve that serves as a pressure reducing valve, the amount of frost on each evaporator and the state of melting of the frost can be made as uniform as possible, thereby improving the operating efficiency of the refrigeration equipment. The aim is to improve.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the solving means of the present invention changes the opening degree of the electric expansion valve according to the frosting state of each evaporator to adjust the evaporator capacity. This aims to equalize the amount of frost formation.

Specifically, the measures taken by the invention of claim 1 are as follows:
As shown in Figure 1 (dotted line area not included), compressor (1)
and the main refrigerant pipe (11) to which the condenser is connected,
A closed refrigerant circuit (14) is provided in which a plurality of branch pipes (11a) and (11b) are connected in parallel to each other, each having an evaporator (6) and an electric expansion valve (8) connected in series. A refrigeration system is assumed.

[0009] As an operation control device for a refrigeration system,
frosting state detection means (Th21) for individually detecting the frosting state of the evaporators (6a), (6b) from the temperature of each of the evaporators (6a), (6b) or the refrigerant state quantity related thereto;
(Th22), and during the operation of the refrigeration system, receives the output of each of the frosting state detection means (Th21) and (Th22), and depending on the frosting state of each evaporator (6a) and (6b),
A defrosting operation control means (51) is provided for controlling the defrosting operation of the evaporators (6a) and (6b).

[0010]Furthermore, during operation of the refrigeration system, when the temperature of one of the evaporators (6a or 6b) reaches the frosting start temperature in response to the output of each of the frosting state detection means (Th21) and (Th22), In this case, a pre-defrost opening reduction means (52) is provided which controls the opening of the electric expansion valve (8a or 8b) of the evaporator (6a or 6b) to be narrowed.

The means taken by the invention of claim 2 is that in the invention of claim 1, the defrosting operation control means (51) is controlled so that the temperature of either one of the evaporators (6a or 6b) reaches a predetermined frosting level. This is because the defrosting operation of all the evaporators (6a) and (6b) is started when the defrosting start temperature corresponding to the amount is reached.

The means taken by the invention of claim 3 is that the refrigerant circuit (14) in the invention of claim 1 or 2 is configured to be able to switch cycles, and the defrosting operation control means (51) is configured to perform reverse cycle defrosting. The driver shall be responsible for driving.

Furthermore, during the defrosting operation, when the temperature of either evaporator (6a or 6b) reaches the melting temperature of frosting based on the output of each frosting state detection means (Th21) and (Th22), , the opening reduction means (53) during defrosting is provided to control the opening degree of the electric expansion valve (8a or 8b) of the evaporator (6a or 6b) to be narrowed down.

The means taken by the invention of claim 4 is that in the invention of claim 1, 2, or 3, the defrosting operation control means (
51) is configured to end the defrosting operation when the temperature of all the evaporators (6a) and (6b) reaches the melting temperature of frosting.

[0015]

[Operation] With the above configuration, in the invention of claim 1, each of the frosting state detection means (Th21), (
When the frosting state of each evaporator (6a), (6b) is detected from the temperature of the evaporator or the related refrigerant state quantity by Th22), the defrosting operation control means (Th22) is activated according to the frosting state. 51), the defrosting operation is controlled.

[0016] Before starting the defrosting operation, when the temperature of any one of the evaporators (for example, 6a) detected by each of the frosting state detection means (Th21) and (Th22) reaches the frosting start temperature, the defrosting operation starts. Since the pre-frost opening reducing means (52) reduces the opening of the electric expansion valve (8a) of the evaporator (6a), the capacity of the evaporator (6a) is reduced, and each The integrated capacities of the evaporators (6a) and (6b) are made as uniform as possible. Therefore, the defrosting operation for melting the frost on each evaporator (6a) and (6b) is efficiently performed, and the operating efficiency of the entire refrigeration system is improved.

In the invention of claim 2, in the invention of claim 1, the defrosting operation control means (51) starts defrosting when the amount of frost on either one of the evaporators (for example, 6a) reaches a predetermined amount. Since the defrosting operation is performed when the temperature is reached, in combination with the effect of the invention of claim 1, efficient defrosting can be achieved without the amount of frost forming on any of the evaporators (for example, 6b) becoming excessive. Frost operation is carried out.

In the invention of claim 3, the defrosting operation control means (
51) during defrosting operation, one of the evaporators (e.g. 6
When the temperature of b) reaches the melting temperature, the defrosting opening reduction means (53) closes the electric expansion valve (8) of the evaporator (6b).
Since the opening of b) is narrowed, the amount of refrigerant circulating to the evaporator (6b) decreases, and the amount of refrigerant circulating to the other evaporator (6a) increases accordingly, promoting the melting of frost. Ru. Therefore, the degree of melting of the frost formed on each evaporator (6a), (6b) is made as uniform as possible, and the defrosting operation time is shortened, so that the operating efficiency of the refrigeration system is improved.

In the invention of claim 4, the defrosting operation control means (
51), the defrosting operation is ended and normal operation is resumed when the frost on all the evaporators (6a) and (6b) has melted, so the operating efficiency of the refrigeration system is improved. The frost on each evaporator (6a), (6b) is reliably melted while maintaining the temperature.

[0020]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIG. 2 and subsequent drawings.

FIG. 2 shows a refrigerant piping system of a multi-type air conditioner according to an embodiment of the present invention.
A) A plurality of indoor units (not shown) are connected in parallel. Inside the outdoor unit (A),
A first compressor (1a) whose capacity is adjusted by an inverter (2a) whose output frequency is variably switched in 10Hz increments in the range of 30 to 70Hz, and an unloader (2b) which operates differentially depending on the pilot pressure. ), the capacity of which is adjusted in two stages: fully loaded (100%) and unloaded (50%), and a check valve (2c).
variable capacity compressors (
1), an oil separator (4) that separates oil from the gas discharged from the compressor (1), and an oil separator (4) that switches as shown in the solid line in the figure during cooling operation and as shown in the broken line in the figure during heating operation. A road switching valve (5) and two heat source side heat exchangers (6a) and (6b) that function as a condenser during cooling operation and an evaporator during heating operation, adjust the refrigerant flow rate during cooling operation, and function as an evaporator during heating operation. Two outdoor electric expansion valves (8a) that perform a throttling action on the refrigerant.
8b), a receiver (9) for storing the liquefied refrigerant,
An accumulator (10) is provided as the main equipment.

[0022]Then, the compressor (1) and the receiver (9)
) and the accumulator (10) are sequentially connected in series by the main refrigerant pipe (11), and each heat source side heat exchanger (6a
), (6b) and each outdoor electric expansion valve (8a), (8b)
are connected in series by two branch pipes (11a) and (11b), respectively, and each branch pipe (11a),
The refrigerant circuits (11b) are connected in parallel to the main refrigerant pipes (11), and are closed refrigerant circuits (11b) in which refrigerant circulates.
4) is configured.

Here, each device of the outdoor unit (A) is housed in one casing (not shown),
One of the heat source side heat exchangers (6a) and (6b) has a first fan (31a) that can be switched between a high air volume and a low air volume, and a second fan that has a constant air volume. fan(
31b), and the other heat source side heat exchanger (
6b) is installed in the ventilation path of a third fan (31c) that can be switched between high air volume and constant air volume. Two air outlets are provided corresponding to each of the heat source side heat exchangers (6a) and (6b), and the structure is configured into a so-called two-sided heat exchanger that individually performs heat exchange with outdoor air. ing.

Next, a heating overload control bypass path (41) is provided which connects the discharge pipe and the liquid pipe side so that the discharge gas (hot gas) can be bypassed. The bypass path (4
1) branches into two branch paths (41a) and (41b) corresponding to the two heat source side heat exchangers (6a) and (6b), and since these have the same configuration, one Only the branch road (41a) will be explained.
41a), an auxiliary heat exchanger (42a) installed in a common air passage with the heat source side heat exchanger (6a), and a capillary tube (43a) are successively connected in series. The above configuration is the same for the other branch path (41b). And heating overload control bypass path (41)
At the confluence of the refrigerant, there is an electromagnetic on-off valve (4
4) is provided.

[0025] During cooling operation, the electromagnetic on-off valve (44) is always on or in an open state, and a part of the discharged gas is transferred from the main refrigerant circuit (14) to the heating overload control bypass path (41). By bypassing, a part of the discharged gas is condensed in the auxiliary heat exchangers (42a), (42b) to support the capacity of the heat source side heat exchangers (6a), (6b), and each capillary tube (43a) and (43b) are used to balance the pressure loss on the heat source side heat exchangers (6a) and (6b). Also, during heating operation,
When the high pressure rises excessively, the electromagnetic on-off valve (4)
4) Instead of opening the valve, first reduce the capacity of the compressor (1), and if the high-pressure side pressure continues to rise excessively, fully close one of the outdoor electric expansion valves (8a).
The evaporation capacity is lowered to accommodate the low capacity indoors. Then, only when the overload condition is not resolved even with the fully closed control of the outdoor electric expansion valve (8a), the electromagnetic on-off valve (44) is opened and a portion of the discharged gas is transferred to each auxiliary heat exchanger (42a). , (42b) to balance the evaporation capacity of the heat source side heat exchanger (6b).

Further, (51) connects the liquid line of the main refrigerant circuit (14) and the suction side of each compressor (1a), (1b), and adjusts the degree of superheating of the suction gas during heating and cooling operation. A liquid injection bypass path for
Each bypass road (51) has two branch roads (51a) on the way.
), (51b), and branch paths (51a), (51b).
) includes an injection solenoid valve (52a) that opens and closes in conjunction with the on/off of each compressor (1a), (1b),
(52b), capillary tubes (53a), (53
b) are respectively provided.

In addition, (15) is a method for cooling the suction refrigerant by heat exchange between the suction refrigerant in the suction pipe and the liquid refrigerant in the liquid pipe to compensate for the increase in the degree of superheating of the refrigerant in the connecting pipe. It is a tube heat exchanger.

[0028] In addition to the above-mentioned main equipment, various auxiliary equipment are provided. (7a) and (7b) are supercoolers provided at the liquid side inlets of each heat source side heat exchanger (6a) and (6b), and (21) is a bypass path (21) of the second compressor (1b).
20) is an unloader solenoid valve which is "open" when the second compressor (1b) is stopped and in the unloaded state, and "closed" when the second compressor (1b) is in the fully loaded state. A capillary tube interposed in the bypass path (20), (
24) is installed in the pressure-equalizing hot gas bypass line (23) that connects the discharge pipe and the suction pipe, and is opened for a certain period of time before restarting when the compressor (1) is stopped due to a thermo-off state, etc. The pressure equalizing solenoid valve (25) is the capillary tube (26
) from the oil separator (4) to each compressor (1a),
An oil return pipe (27) for returning oil to (1b) is connected to each compressor (1a) and (1) via a capillary tube (28).
This is an oil equalizing pipe that connects the domes in b).

Furthermore, sensors are arranged in the air conditioner, and (Th1) is an outside air thermistor (Th1) installed on the outer surface of the casing of the outdoor unit (A) to detect the temperature T1 of the outdoor air. Th21 ) and (Th22 ) are respectively arranged on the liquid pipe side of each heat source side heat exchanger (6a) and (6B), and during heating operation when the heat source side heat exchanger (6a) and (6b) act as an evaporator. Each heat source side heat exchanger (6a), (6b
), the first and second diasters individually detect the temperature of (T
h31 ) and (Th32 ) are each compressor (1a
), (1b) are arranged in the discharge pipes to detect the temperature of the discharged refrigerant, (Th41), (Th42
) are arranged on the gas side of each branch pipe (11a) and (11b), that is, on the part that becomes the suction line during heating operation, and detect the temperature of the superheated refrigerant being sucked in, and (P1) is the discharge pipe thermistor. A high pressure sensor (P2) is arranged in the suction line and detects the pressure on the high pressure side, and a low pressure sensor (P2) is arranged in the suction line and detects the pressure on the low pressure side. In addition, during heating operation of the air conditioner, the superheated refrigerant temperature T4 detected by each of the above-mentioned suction pipe thermistors (Th41) and (Th42) and each de-icer (Th21) and (Th2)
The degree of superheating Sh of the refrigerant is detected from the temperature difference with the evaporation temperature T2n (n = 1, 2) detected in step 2).

[0030] Each of the above sensors is connected by a signal line to a controller (not shown) that controls the operation of the air conditioner. It is designed to control the operation of each device.

[0031] During heating operation of the air conditioner, the four-way switching valve (
5) is switched to the dashed line side in the figure, and the compressor (1)
The gas refrigerant discharged from the indoor unit is condensed and liquefied by heat exchange with the indoor air, becomes a liquid refrigerant, and is stored in the receiver (9).
b), and each outdoor electric expansion valve (8a), (8
b), and each heat source side heat exchanger (6a), (6b)
It is circulated so that it is evaporated and sucked into the compressor (1). Also, during cooling operation, the four-way switching valve (5) is switched to the solid line side in the figure, and the refrigerant circulation direction is opposite to that during the cooling operation, so that the discharged refrigerant is transferred to each branch pipe (11a), ( 11
b), and flows through each heat source side heat exchanger (6a), (6
In b), it is condensed and liquefied by heat exchange with outdoor air, stored in the receiver (9), and then returned to the compressor (1) as a gas refrigerant by heat exchange with indoor air in the indoor unit. circulates.

Next, regarding the control contents of the controller,
This will be explained based on the flowcharts of FIGS. 3 and 4.

FIG. 3 shows the details of the operation control of the air conditioner. In step ST1, it is determined whether or not there is a heating request. If it is a heating request, in step ST2, it is determined whether or not it is in operation, and the operation is started. If inside, in step ST3, the temperature T2n (n = 1,
2) Regarding (dialysis temperature), the formula T2n<0.
It is determined whether or not 5×T1 −5 holds true, and if this relationship holds true for any de-Icer temperature T2n,
It is determined that frost formation has started on the heat source side heat exchanger (6a or 6b), and the process proceeds to step ST4, where the alarm flag DEFST1 on the heat source side heat exchanger (6a or 6b) is set to "
1”.

Furthermore, in step ST5, the formula T2n<0.5×T1 −
10 is established, and if this relationship is established,
It is determined that it is necessary to perform a defrosting operation because the amount of frost on one of the heat source side heat exchangers (6a or 6b) has reached a predetermined amount, and in step ST6, a 5-minute timer for standby control (not shown) is activated. The above control is repeated until the 5-minute timer counts up in step ST7. Then, when the 5 minute timer counts up, step ST
After the alarm flag DEFST1 is set to "0" in step ST9, the defrosting flag DEFST2 is set to "1" in step ST9, and a defrosting operation to be described later is started. On the other hand, during the counting of the 5-minute timer, the formula T
When 2n<0.5×T1 −10 does not hold, it is determined that there is a possibility of false detection of the de-Icer (Th21 or Th22), and the process moves to step ST10, where the 5-minute timer is reset, and then the process moves to step ST1. Go back and repeat the above control.

[0035] Note that the above steps ST1, ST2, ST
In the control of step 3, when there is no heating request, when the operation is in progress, or when the formula T2n<0.5×T1 -5 does not hold, the process moves to step ST11 and both the alarm flag DEFST1 and the defrosting flag DEFST2 are set. Set to "0".

Next, FIG. 4 shows the contents of the opening degree control of each outdoor electric expansion valve (8a or 8b). In step SR1, it is determined whether or not there is a heating request. If it is a heating request, step SR
In step 2, it is determined whether or not the valve is in operation, and if it is not in operation, the process proceeds to step SR3, where the valve opening degree is fully closed. Next, in step SR4, it is determined whether the defrost flag DEFST2 set by the control shown in FIG.
If EFST2 is not "1", in step SR5,
Furthermore, it is determined whether the alarm flag DEFST1 is "1" or not. If the alarm flag DEFST1 is not "1", the process proceeds to step SR6, where the superheat degree control target value S
hs is set to the standard value 5 (℃), and if the alarm flag DEFST1 is "1", the process moves to step SR7 and the heat source side heat exchanger (6a or 6b) where frosting has started is set.
) control target value Shs for the degree of superheating in order to suppress the progress of frost formation.
By changing the temperature to a high value of 20 (° C.), the valve opening degree is narrowed and the evaporation capacity of the heat source side heat exchanger (6a or 6b) is reduced. In addition, in the determination in step SR4 above, DEF
When ST2=1, the control shifts to opening degree control during defrosting operation, which will be described later (see FIG. 7).

If it is determined in step SR1 that there is no heating request, the process moves to step SR9, and it is judged whether or not the operation is in progress. If the operation is in progress, the process proceeds to step SR10, where the valve opening degree is fully opened (2000 pulses). ), and if the engine is not in operation, the process moves to step SR11 and the valve opening is set to a low opening of 200 pulses.

Next, the control contents during the defrosting operation will be explained based on FIGS. 5 to 7. FIG. 5 shows the details of the control for determining the representative value T2 of the de-Icer (Th21), (Th22) during the defrosting operation.
) side and compare the heights of the de-icer temperatures T21 and T22 detected, and if T21>T22, step S
If T2 = T22 at P2, and T21<T22,
In step SP3, T2 = T21. In other words, the detection value T2 of each diaster (Th21), (Th22)
1 and T21, the lower one is determined as the representative value T2.

FIG. 6 shows the control contents during the defrosting operation. In step ST21, the four-way selector valve (5) is switched to the cooling cycle side to start the defrosting operation in the reverse cycle, and at the same time, the defrosting operation is started. 1 to set the upper limit of time to 10 minutes
A 0-minute timer (not shown) starts counting, and in step ST22, when the representative value T2 of the de-Icer temperature determined by the above control becomes higher than the predetermined temperature 12.5 (°C), the timer starts counting for 10 minutes in step ST23. Defrost operation is performed until the timer counts up, and when the 10 minute timer counts up, either heat source side heat exchanger (6a), (6b)
It is determined that the frost has also melted, and the normal heating operation is resumed in step ST24.

FIG. 7 shows the control contents of the opening degrees of the outdoor electric expansion valves (8a) and (8b) during the defrosting operation. In step SR21, each heat source side heat exchanger (6a) and (6b
) and the frost melting temperature 12.5 (°C), T21>12.5 (
℃), and determine whether T21 (or T22) > 12.5
If T21 (or T22) > 12.5 (°C), the valve opening is set to fully open in step SR22, but if T21 (or T22) > 12.5 (°C), the process proceeds to step SR23 and the valve opening is set to half open at 1000.
Set to pulse.

In each of the above flowcharts, the control in steps ST21 to ST23 constitutes the defrosting operation control means 51 according to the invention of claim 1, and the control in step SR7 constitutes the pre-defrost opening reduction means ( 52) is configured. Furthermore, the control in step SR23 constitutes a defrosting opening reduction means (53).

Therefore, in the control corresponding to the invention of claim 1 of the above embodiment, during the heating operation of the air conditioner, each de-icer (frosting state detection means) (Th21), (Th
22), the evaporator temperature, that is, the heat source side heat exchanger (6
When the frosting state of the heat source side heat exchangers (6a), (6b) is detected from the temperatures T21, T22 of a), (6b) or the refrigerant state quantities related thereto, the defrosting is performed according to the frosting state. The defrosting operation (defrosting operation by reverse cycle in the above embodiment) is controlled by the frost operation control means (51).

At that time, before the defrosting operation, each heat source side heat exchanger (evaporator) (6a), (6
b) are housed in the same casing, the frosting state of each heat source side heat exchanger (6a), (6b) may not be uniform due to uneven flow of each fan (31a) to (31c), etc. However, the integrated capacity of one of the heat source side heat exchangers (for example, 6a) is particularly large, and frost may form first. Therefore, if the heating operation is continued without considering the difference in the frost formation conditions of each evaporator as in the conventional one, the frost formation on the other heat source side heat exchanger (6b) will not reach the defrosting operation start condition. Performing a defrosting operation even though there is no defrosting operation may cause a deterioration in the efficiency of the air conditioner, or the heat exchanger on both heat source sides (6a),
Continuing the heating operation until the defrosting operation start condition (6b) is satisfied causes problems such as excessive frost formation and loss of reliability.

In contrast, in the above embodiment, each de-icer (frosting state detection means) (T
h21) and (Th22), that is, the temperature T21 of the heat source side heat exchanger (for example, 6a) reaches the frosting start temperature, the pre-defrost opening reduction means (52) Since the opening degree of the outdoor electric expansion valve (8a), which is the pressure reducing valve of the heat source side heat exchanger (6a), is reduced, the capacity of the heat source side heat exchanger (6a) is reduced, and each Heat source side heat exchanger (6a), (6b)
The integration capabilities of the two are made as uniform as possible. Therefore, the defrosting operation for melting the frost on each of the heat source side heat exchangers (6a) and (6b) is performed efficiently, and the operating efficiency of the entire air conditioner is improved.

In the above embodiment, two heat source side heat exchangers (6a) and (6b) are installed in the casing of the outdoor unit (A) of the air conditioner having a so-called heat pump circuit.
) has been described, but the present invention is not limited to such an embodiment.
For example, the present invention can also be applied to a refrigerator in which a large number of evaporators are arranged in a refrigerant circuit. However, in an air conditioner having a two-sided heat exchange type outdoor unit (A) like the above embodiment, when the outdoor unit (A) is installed on the roof of a building, depending on the surrounding situation, one heat source side may The effect of the present invention is particularly great because the air flow to the exchanger is often blocked by an adjacent building, resulting in uneven air flow.

Furthermore, in the above embodiment, a case has been described in which the degree of opening of each outdoor electric expansion valve (8a), (8b) is controlled by degree of superheating, but the present invention is not limited to such embodiment. For example, the present invention can also be applied to an operation control device that performs capacity control according to the required capacity in each refrigerator in a refrigerator having a plurality of evaporators.

Furthermore, in the above embodiment, the outdoor motorized expansion valve (8a) of the heat source side heat exchanger (for example, 6a) where frost has formed
Although the opening degree of the outdoor electric expansion valve (8a) is restricted by changing the value of the target degree of superheat to a higher value, the restriction control of the opening degree of the outdoor electric expansion valve (8a) is not limited to this example, and may be uniformly performed, for example. Control such as half-opening (1000 pulses) or fully closing may be performed.

Further, in the invention of claim 1, the defrosting operation by the defrosting operation control means (51) is not limited to the reverse cycle as in the above embodiment, but may also be a defrosting operation using a hot gas bypass, for example. Needless to say, this is a good thing.

Next, in the above embodiment, corresponding to the invention of claim 2, the defrosting operation control means (51) controls the amount of frosting on one of the heat source side heat exchangers (for example, 6a) to a desired level. Although the defrosting operation is carried out when a certain defrosting start temperature is reached, the present invention is not limited to this embodiment. The defrosting operation may be performed when the temperature reaches the defrosting start temperature. However, as in the invention of claim 2, if the defrosting operation is performed when the temperature of one of the heat source side heat exchangers (for example, 6a) reaches the defrosting start temperature, one of the heat source side heat exchangers (for example, 6a) It is possible to reliably prevent the amount of frost on the side heat exchanger (for example, 6b) from becoming excessive, and in combination with the effect of the invention of claim 1, it is possible to perform defrosting operation reliably and efficiently. It has the advantage of being possible.

Next, in the part corresponding to the invention of claim 3 in the above embodiment, during the defrosting operation by the defrosting operation control means (51), any of the heat source side heat exchangers (for example, 6b)
When the temperature T22 reaches the melting temperature, the opening degree reduction means (53) during defrosting reduces the opening degree of the outdoor electric expansion valve (8b) of the heat source side heat exchanger (6b). The amount of refrigerant circulated to the heat exchanger (6b) decreases, and the amount of refrigerant circulated to the other heat source side heat exchanger (6a) increases accordingly. Therefore, the degree of melting of frost on each heat source side heat exchanger (6a), (6b) is made as uniform as possible, and the defrosting operation time is shortened, so that the operating efficiency of the air conditioner is improved. become.

[0051] In the above embodiment, in accordance with the invention of claim 4, the end of the defrosting operation is determined when the frost on both heat source side heat exchangers (6a) and (6b) is melted. However, the present invention is not limited to such embodiments; for example, the defrosting operation may be terminated when the average temperature of each heat source side heat exchanger (6a), (6b) reaches a predetermined value. Controls like (
For example, control such as returning to normal operation when the detected value of the low pressure sensor (P2) in the above embodiment reaches a predetermined value is also possible. However, as in the invention of claim 4, when the temperature of both heat source side heat exchangers (6a) and (6b) reaches the melting temperature of frost, the defrosting operation is controlled to end and normal operation is resumed. By doing this, each heat source side heat exchanger (6
The frost formed in a) and (6b) is reliably melted. Therefore, together with the effect of the invention of claim 3, there is an advantage that defrosting can be reliably performed while maintaining good operating efficiency of the air conditioner.

Furthermore, in the above embodiment, the heat source side heat exchanger (
6a) and (6b) were detected by the de-icers (Th21) and (Th22) placed in the liquid pipes, but for example, the suction refrigerant temperature and , Suction pipe sensor (Th41
), (Th42), the same effect can be obtained by detecting the frosting state from the evaporation pressure equivalent saturation temperature detected by a pressure sensor, that is, the refrigerant state quantity related to the evaporator temperature.

[0053]

As explained above, according to the invention of claim 1, a refrigeration system equipped with a refrigerant circuit in which a plurality of evaporators and electric expansion valves are arranged in parallel with each other in the refrigerant circuit. As an operation control device, it performs defrosting operation according to the frosting state of each evaporator detected from the temperature of each evaporator, and when any evaporator frosts, it opens the electric expansion valve of that evaporator. Since the capacity of the evaporator is reduced, the integrated capacity of each evaporator immediately before the start of frost operation can be equalized as much as possible, thereby improving the operating efficiency of the entire refrigeration system. be able to.

According to the invention of claim 2, in the invention of claim 1, when the temperature of one of the evaporators reaches the defrosting start temperature corresponding to the predetermined amount of frost formation during operation of the refrigeration system, Since the defrosting operation is performed, in addition to the effect of the invention of claim 1, defrosting can be reliably performed.

According to the invention of claim 3, in the invention of claim 1 or 2, when the temperature of any one of the evaporators reaches the melting temperature of frost during the defrosting operation, the electric expansion of the evaporator is activated. Since the opening degree of the valve is reduced, by increasing the amount of refrigerant circulating to other evaporators, it is possible to equalize the degree of frost melting in each evaporator as much as possible. It is possible to shorten the frost operation time and improve the operating efficiency of the refrigeration system.

According to the invention of claim 4, the above-mentioned claim 1,
In the invention of 2 or 3, the defrosting operation is ended and normal operation is resumed when all the evaporator frost has melted during the defrosting operation, so that the operating efficiency of the refrigeration equipment is maintained well. At the same time, frost on each evaporator can be reliably melted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the invention.

FIG. 2 is a refrigerant piping system diagram of the air conditioner according to the embodiment.

FIG. 3 is a flowchart showing the details of operation control before defrosting operation.

FIG. 4 is a flowchart showing the details of opening control of the electric expansion valve before defrosting operation.

FIG. 5 is a flowchart showing the details of the representative value determination control of the de-Icer during the defrosting operation.

FIG. 6 is a flowchart showing the details of operation control during defrosting operation.

FIG. 7 is a flowchart showing details of opening control of the electric expansion valve during defrosting operation.

[Explanation of symbols]

1 Compressor 6a, 6b Heat source side heat exchanger (evaporator) 8a, 8b
Outdoor electric expansion valve 11 Main refrigerant piping 11a, 11b Branch piping 14 Main refrigerant circuit

Claims (4)

[Claims] Claim 1: A plurality of branches each having an evaporator (6) and an electric expansion valve (8) connected in series to a main refrigerant pipe (11) to which a compressor (1) and a condenser are connected. Piping (1
1a) and (11b) connected in parallel to each other, the temperature of each of the evaporators (6a) and (6b) or the refrigerant state quantity related thereto. Frosting state detection means (Th21), (Th2) for individually detecting the frosting state of the evaporators (6a), (6b)
2) During the operation of the refrigeration system, the output of each of the frosting state detection means (Th21) and (Th22) is received, and the evaporation is detected according to the frosting state of each evaporator (6a) and (6b). A defrosting operation control means (51) for controlling the defrosting operation of the refrigeration equipment (6a) and (6b), and each of the above-mentioned frosting state detection means (Th21),
(Th22), one of the evaporators (6a
or 6b) when the temperature reaches the frosting start temperature, a pre-defrosting opening reduction means (52) that controls the opening of the electric expansion valve (8a or 8b) of the evaporator (6a or 6b) to be narrowed. An operation control device for a refrigeration system, characterized by comprising: 2. In the operation control device for a refrigeration apparatus according to claim 1, the defrosting operation control means (51) is arranged such that the temperature of either one of the evaporators (6a or 6b) corresponds to a predetermined frost amount. When the defrosting start temperature is reached, all evaporators (6a
), (6b). 3. In the operation control device for a refrigeration system according to claim 1 or 2, the refrigerant circuit (14) is configured to be able to switch between cycles, and the defrosting operation control means (51) performs a reverse cycle defrosting operation. In addition, during defrosting operation,
Upon receiving the output of each frost state detection means (Th21) and (Th22), when the temperature of either evaporator (6a or 6b) reaches the melting temperature of frost, the evaporator (6a or 6b) An operation control device for a refrigeration system, characterized in that it includes a defrosting opening reduction means (53) that controls the opening of an electric expansion valve (8a or 8b) to be narrowed. 4. In the operation control device for a refrigeration equipment according to claim 1, 2 or 3, the defrosting operation control means (51) is configured such that the temperature of all the evaporators (6a), (6b) is at a level at which frost is formed. An operation control device for a refrigeration device, characterized in that the defrosting operation ends when the melting temperature is reached.