JPH06249484A - Air conditioning device - Google Patents

Abstract

PURPOSE:To remove frost assuredly and quickly while suppressing the cost of the device from increasing. CONSTITUTION:A compressor 11, outdoor heat-exchanger 13, expansion valve 15 and indoor heat-exchangers 16a-16d are orderly connected by conduits 17a-17f, and the temperature of a refrigerant which is drawn into the compressor 11 is detected by a first refrigerant temperature sensor 31, and a lower pressure equivalent saturation temperature is detected by a second refrigerant temperature sensor 32 respectively, and the degree of superheat is controlled by a control unit 1 based on the detected signals. Then, the difference between the temperature of the outside air which is detected by an outside air temperature sensor 34 and the temperature of the indoor heat-exchanger 13 which is detected by a single heat-exchanger temperature sensor 33 is obtained, and it is judged whether the difference is not more than a specified value or not. At the same time, when it is judged that the difference is not more than the specified value, it is judged whether the detected temperature of the second refrigerant temperature sensor 32 is not more than a specified value or not, and when the detected temperature is judged to be not more than the specified value, the defrosting control for the outdoor heat-exchanger 13 is started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner having a function of defrosting an outdoor heat exchanger in the cold season.

[0002]

2. Description of the Related Art Conventionally, an air conditioner of this type is known, for example, as shown in FIG. In this air conditioner, a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13 having a fan 14, an electric expansion valve 15 and indoor heat exchangers 16a to 16d are sequentially connected by pipelines 17a to 17f. It is composed of a heat pump type refrigerant circuit. Indoor heat exchanger 1
6a to 16d are connected in parallel between the conduits 17d and 17e via the liquid closing valve 18, the header 19, the indoor expansion valves 20a to 20d and the header 21, and the gas closing valve 22 and arranged in a plurality of chambers. On the other hand, the liquid receiver 23 having the filter 24 in the pipe line 17d and the first opening / closing valve 25 in the pipe line 17a are provided respectively, and the upstream side of the first opening / closing valve 25 and the pipe line 17c are connected to each other.
They are connected by a defrost pipe line 26 provided with an on-off valve 27. Further, the liquid receiver 23 and the pipe line 17f are connected by a pipe line 28 provided with a capillary tube 29, and the pipe line 28 on the downstream side of the capillary tube 29 detects the saturation temperature of the refrigerant corresponding to the low pressure. 2 Refrigerant temperature sensor 32
A first refrigerant temperature sensor 31 for detecting the temperature of the refrigerant sucked into the compressor 11 is provided at each of 7f. Further, a heat exchanger temperature sensor 33 is provided in the outdoor heat exchanger 13, and an outdoor air temperature sensor 34 that detects the temperature of outdoor air is provided outdoors, respectively, and each part of the refrigerant circuit is controlled based on the detection signals of the sensors 31 to 34. There is provided a control unit 35 for controlling.

During heating operation, the control unit 35 opens the first on-off valve 25, closes the second on-off valve 27, and closes the four-way switching valve 12
To the passage indicated by the broken line, and the gas refrigerant discharged from the compressor 1 is transferred to the indoor heat exchanger 16 as indicated by the solid line arrow in FIG.
It is condensed in a to 16d and circulated so as to be evaporated in the outdoor heat exchanger 13. On the other hand, during cooling operation, the four-way switching valve 1
2 is switched to the passage shown by the solid line, and the discharged gas refrigerant is circulated so as to be evaporated in the indoor heat exchangers 16a to 16d and condensed in the outdoor heat exchanger 13 as shown by the broken line arrow in FIG.
Then, in both cases of cooling and heating, the first refrigerant temperature sensor 3
Difference between the suction refrigerant temperature Da to the compressor detected by No. 1 and the low pressure equivalent saturation temperature De detected by the second refrigerant temperature sensor 32.
The opening degree of the expansion valve 15 and the rotation speed of the compressor 11 are controlled and the opening degrees of the indoor expansion valves 20a to 20d are adjusted so that (Da-De) becomes a predetermined value (superheat degree). , The degree of superheat of the evaporated refrigerant in each chamber and the amount of refrigerant distributed to each chamber are controlled.

Further, during the heating operation, the control unit 35 causes the temperature Dc detected by the heat exchanger temperature sensor 33 to have a predetermined value (for example, 0).
(° C) or less, it is determined whether or not frost is attached to the outdoor heat exchanger 13, and when it is determined that frost is attached, the outdoor fan 14
Then, the indoor fans are stopped, the first opening / closing valve 25 and the expansion valve 15 are closed, and the second opening / closing valve 27 is opened while the four-way switching valve 12 is kept in the heating operation position. Then, the high-temperature discharge gas refrigerant from the compressor 11 changes as indicated by the one-dot chain line arrow in FIG.
Flowing from the defrost pipe line 26 to the outdoor heat exchanger 13, the frost adhering thereto is removed.

[0005]

However, in the above-described conventional air conditioner, the circulating refrigerant flows through the outdoor heat exchanger 13 in multiple passes after being branched by the flow divider 30. Causes a difference in the flow rate of the refrigerant between the passes, that is, a drift. Therefore, the outdoor heat exchanger 13
If the location where the heat exchanger temperature sensor 33 is provided corresponds to a path where the flow rate of the refrigerant is reduced due to uneven flow, the sensor 3 is used.
Detected temperature Dc of 3 is higher than the original temperature and proper temperature measurement cannot be performed, and defrosting operation is not started even if the outdoor heat exchanger may frost at 0 ° C or less. become. If such a situation is neglected, the capacity of the air conditioner will be deteriorated and the compressor will malfunction. In order to solve such a problem, a temperature sensor may be attached to each path of the outdoor heat exchanger 13, and the risk of frost formation may be determined by the lowest temperature detected by these temperature sensors. Then,
There is a problem that several temperature sensors are required, which causes an increase in the product price of the air conditioner.

Therefore, an object of the present invention is to improve the cost of the product by devising a method of accurately detecting frost formation by utilizing an existing temperature sensor other than the temperature sensor of the outdoor heat exchanger. An object is to provide an air conditioner that can appropriately perform defrosting operation.

[0007]

In order to achieve the above object, the air conditioner of the present invention is, as illustrated in FIG.
Compressor 11 and outdoor heat exchanger 1 that can operate as an evaporator
3, the expansion valve 15 and the indoor heat exchangers 16a to 16d capable of operating as condensers are sequentially connected by the pipelines 17a to 17f, and the pipeline Da is used to detect the temperature Da of the refrigerant sucked into the compressor 11. The difference between the heat pump type refrigerant circuit provided with the refrigerant temperature sensor 31 and the second refrigerant temperature sensor 32 for detecting the saturation temperature De of the refrigerant corresponding to the low pressure and the detection signals of the first and second refrigerant temperature sensors 31, 32 is In the one provided with the control unit 1 for controlling the opening degree of the expansion valve 15 and the rotation speed of the compressor 11 so as to be a predetermined value, the outside air temperature sensor 34 for detecting the temperature of the outside air and the outdoor heat exchanger. The outside air temperature Do and the outside heat exchanger temperature Dc are detected based on the detection signals of the single heat exchanger temperature sensor 33 that detects the temperature and the outside air temperature sensor 34 and the heat exchanger temperature sensor 33 during operation.
Of the heat exchanger temperature sensor 33. When the difference (Do-Dc) is equal to or less than a constant value α, the deviation determination unit 1 determines whether the difference is greater than a certain value α. Instead of a signal, it is determined whether or not the temperature De represented by the detection signal of the second refrigerant temperature sensor 32 is equal to or lower than a constant value β, and when it is determined to be affirmative, control for defrosting the outdoor heat exchanger 13 The defrosting control starting means 1 for starting is provided.

[0008]

During the heating operation, the gas refrigerant discharged from the compressor 11 circulates in the refrigerant circuit so that it is condensed in the indoor heat exchangers 16a to 16d and evaporated in the outdoor heat exchanger 13, and the first refrigerant is used. The control unit 1 controls the difference (Da-De) between the suction refrigerant temperature Da to the compressor detected by the refrigerant temperature sensor 31 and the low pressure equivalent saturation temperature De detected by the second refrigerant temperature sensor 32 to be a predetermined value. Thus, the opening degree of the expansion valve 15 and the rotation speed of the compressor 11 are controlled (superheat degree control).

It is assumed that frost has formed on the outdoor heat exchanger 13 at the start or during the heating operation in the cold season. The nonuniform flow determination means 1 detects the outside air temperature Do detected by the outside air temperature sensor 34,
The difference in the temperature Dc of the outdoor heat exchanger 13 detected by the heat exchanger temperature sensor 33 is obtained, and it is determined whether or not this difference (Do-Dc) is less than or equal to a constant value α. When the nonuniform flow occurs in the outdoor heat exchanger 13, the heat exchanger temperature Dc becomes higher than that in the normal state, approaches the outdoor air temperature Do, and is determined as positive. When no nonuniform flow occurs, it is determined as no. If it is determined to be affirmative, the temperature Dc is not the accurate temperature of the outdoor heat exchanger 13 and therefore cannot be used to determine the necessity of defrosting, and the second refrigerant temperature sensor provided in the duct 17f having no drift is provided. The judgment should be made by the low pressure equivalent saturation temperature De detected by 32, that is, the temperature of the dry saturated steam at the outlet of the evaporator (outdoor heat exchanger 13) in the cycle diagram. On the other hand, if it is determined to be no, the temperature Dc indicates the accurate temperature of the outdoor heat exchanger 13, and therefore it is possible to determine whether defrosting is necessary or not based on this temperature. Therefore, when it is determined that the answer is positive, the defrosting control starting means 1 determines that the heat exchanger temperature sensor 33
In place of the detected temperature Dc of No. 2, the detected temperature De of the second refrigerant temperature sensor 32 is determined to be equal to or less than a constant value β (for example, 0 ° C.), and when affirmative, for example, from the compressor 11 Defrost control is started by directly flowing a high-temperature gas refrigerant to the outdoor heat exchanger 13. On the other hand, when it is determined to be no, as in the conventional case, the control unit 1 determines whether or not the temperature Dc of the outdoor heat exchanger is below a certain value, and when it is determined to be affirmative, the same defrosting is performed. Control is started.

[0010]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 shows an example of the air conditioner of the present invention. This air conditioner has the same configuration as the refrigerant circuit described in FIG. 3 except for the configuration of the control unit 1, and the same members. Are given the same numbers. That is, the compressor 1
1, an outdoor heat exchanger 1 having a four-way switching valve 12 and a fan 14
3, the expansion valve 15 and the plurality of indoor heat exchangers 16a to 16d are sequentially connected by the pipelines 17a to 17f, the pipelines 17a and 17c are connected by the defrost pipeline 26, and the suction side pipeline 17 is connected.
First refrigerant temperature sensor 3 for detecting the suction refrigerant temperature Da at f
1. The second refrigerant temperature sensor 32 for detecting the low pressure equivalent saturation temperature De in the pipe 28, the single heat exchanger temperature sensor 33 in the outdoor heat exchanger 13, and the outdoor air temperature sensor 34 in the outdoor, respectively. A control unit 1 that controls each unit of the refrigerant circuit based on the detection signals of 31 to 34 is provided.

The control unit 1 is the control unit 35 described with reference to FIG.
The same control is performed, and it also serves as a drift detection unit and a defrost control start unit. That is, the control unit 1 serves as the non-uniformity determination means for determining the outside air temperature Do detected by the outside air temperature sensor 34 and the outdoor heat exchanger temperature Dc detected by the heat exchanger temperature sensor 33 at the start of heating operation or during heating operation. A difference is obtained, and it is determined whether or not this difference (Do-Dc) is less than or equal to a constant value α. This is because in the Ph diagram of the heat pump cycle of FIG. 2 (however, Do on the vertical axis represents the saturation temperature equivalent to the pressure for convenience), if there is no drift, the temperature Dc detected by the temperature sensor 33 is detected.
Accurately represents the temperature corresponding to the expansion valve outlet and the evaporator inlet at the lower left corner of the above diagram. However, if a drift occurs, the temperature approaches the outside air temperature detected by the outside air temperature sensor 34 indicated by Do on the high temperature side. This is because it falls within the range of (Do-Dc) ≤α as indicated by the arrow. The upper left corner of the Ph diagram of FIG. 2 shows the state of the high-pressure refrigerant liquid at the inlet of the expansion valve 15. This refrigerant liquid passes through the capillary tube 29 from the liquid receiver 23 of FIG. In the conduit 28 opened to 17f, the temperature De of the dry saturated vapor corresponding to the suction pressure is generated. Therefore,
The second refrigerant temperature sensor 32 uses the low pressure equivalent saturation temperature De
Since the first refrigerant temperature sensor 31 detects the refrigerant temperature Da sucked into the compressor, the difference (Da-De) between the detected temperatures of both sensors represents the degree of superheat of the heat pump cycle. .

When the controller 1 determines that (Do-Dc) ≤α, the heat exchanger temperature sensor 33 serves as a defrosting control starting means.
Instead of the detection signal of No. 2, the temperature De represented by the detection signal of the second refrigerant temperature sensor 32 is determined to be equal to or less than a constant value β (for example, 0 ° C.), and when it is determined to be affirmative, the pipe on the discharge side is determined. Road 1
7a closing the first on-off valve 25, opening the second on-off valve 27,
High-temperature discharged refrigerant gas is sent directly to the outdoor heat exchanger 13 via the defrost pipe line 26 to start defrosting. This is because if a drift occurs in the outdoor heat exchanger 13, the temperature Dc detected by the temperature sensor 33 becomes higher than the original temperature as described above, and therefore it cannot be used to determine whether defrosting is necessary, and the evaporator outlet side Defrosting is performed by the low-pressure equivalent saturation temperature indicated by De in FIG. 2 detected by the second refrigerant temperature sensor 32 provided in the ducts 17f, 28 having no drift, that is, the dry saturation temperature at the outlet of the outdoor heat exchanger 13. This is because it is necessary to determine whether or not When it is determined that (Do-Dc)> α, there is no drift and the detected temperature Dc of the temperature sensor 33 represents the original temperature of the outdoor heat exchanger 13. Therefore, the control unit 1 determines the detected temperature Dc. Is determined to be equal to or less than a certain value, the necessity of defrosting is determined, and the above-described defrosting control is started if necessary.

The control unit 1 having the above structure controls the air conditioner as follows. The control unit 1 makes the first
The on-off valve 25 is opened, the second on-off valve 27 is closed, the four-way switching valve 12 is switched to the path indicated by the broken line, and the gas refrigerant discharged from the compressor 1 is transferred to the indoor heat exchanger as indicated by the solid line arrow in FIG. It is condensed in 16a to 16d and circulated so as to be evaporated in the outdoor heat exchanger 13. On the other hand, during the cooling operation, the four-way switching valve 12 is switched to the passage indicated by the solid line, and the discharged gas refrigerant is evaporated in the indoor heat exchangers 16a to 16d and condensed in the outdoor heat exchanger 13 as shown by the broken line arrow in FIG. To circulate. Then, in both cases of cooling and heating, the difference between the refrigerant temperature Da detected by the first refrigerant temperature sensor 31 (see FIG. 2) and the low pressure equivalent saturation temperature De detected by the second refrigerant temperature sensor 32 ( Da-De) is a predetermined value (superheat degree)
The opening degree of the expansion valve 15 and the rotation speed of the compressor 11 are controlled so that Controls the refrigerant distribution amount.

It is assumed that frost is formed on the outdoor heat exchanger 13 at the start or during the heating operation in the cold season. At this time, the control unit 1 obtains the difference between the outside air temperature Do detected by the outside air temperature sensor 34 and the temperature Dc detected by the heat exchanger temperature sensor 33, and determines whether this difference (Do-Dc) is less than or equal to a constant value α. Determine whether. When a drift occurs in the outdoor heat exchanger 13, the detected temperature Dc becomes higher than that in the normal state and approaches the outside air temperature Do, and it is determined to be positive. If no drift is generated, it is determined to be no. If it is determined that ACK, that is, (Do-Dc) ≤α,
The control unit 1 controls the temperature D by the outdoor heat exchanger temperature sensor 33.
Since c cannot be used for determining whether or not defrosting is necessary, instead of this, it is determined whether the temperature De (low pressure equivalent saturation temperature) by the second refrigerant temperature sensor 32 is equal to or lower than a constant value β, and it is determined as positive. When it is determined that frost has adhered, the outdoor fan 14 and each indoor fan are stopped, the first open / close valve 25 and the expansion valve 15 are closed while the four-way switching valve 12 is in the heating operation position, and the second The on-off valve 27 is opened. Then, the hot discharge gas refrigerant from the compressor 11 flows from the defrost pipe line 26 to the outdoor heat exchanger 13 as shown by the one-dot chain line arrow in FIG. On the other hand, the control unit 1 determines whether or not (Do-D
If it is determined that c)> α, the temperature Dc by the heat exchanger temperature sensor 33 indicates the original temperature of the outdoor heat exchanger 13, so it is determined whether or not this temperature Dc is below a certain value.
When the following is determined, the same defrosting control as described above is performed.

As described above, even if the outdoor heat exchanger 13 is a multi-pass type in which uneven flow is apt to occur, a single heat exchanger temperature sensor 33 and a single heat exchanger temperature sensor 33 are not provided in each pass when frost is formed. Since the existing second refrigerant temperature sensor 32 that assists the air conditioner is used for determining whether or not defrosting is necessary, the frost removal can be reliably and quickly performed while suppressing the cost increase of the air conditioner, and the heating capacity of frosting can be improved. Degradation and compressor failure can be eliminated. In the above embodiment, the refrigerant circuit for both cooling and heating in which the circulation direction of the refrigerant can be switched between the forward and reverse directions by the four-way switching valve 12 has been described, but the present invention is only for heating in which the indoor heat exchanger functions only as a condenser. Of course, it can be applied to the refrigerant circuit.

[0016]

As is apparent from the above description, in the air conditioner of the present invention, the compressor, the outdoor heat exchanger, the expansion valve and the indoor heat exchanger are sequentially connected by the pipeline, and the first refrigerant temperature sensor is connected. In the refrigerant circuit in which the suction refrigerant temperature to the compressor is detected by the second refrigerant temperature sensor, the low-pressure equivalent saturation temperature is detected by the second refrigerant temperature sensor, and the superheat degree is controlled by the control unit based on this detection signal, The difference between the outside air temperature detected by and the temperature of the indoor heat exchanger detected by the single heat exchanger temperature sensor was determined, and it was determined whether this difference was less than a certain value, and it was determined that it was less than the certain value. At this time, the defrost control start means determines whether or not the temperature detected by the second refrigerant temperature sensor is equal to or lower than a certain value, and when it is determined that the temperature is less than or equal to the predetermined value, the defrost control of the outdoor heat exchanger is started. , While suppressing the cost increase of the device, Real and quickly defrost can be eliminated failure reduction and compressor heating capacity due to frost formation in.

[Brief description of drawings]

FIG. 1 is a refrigerant circuit diagram showing an embodiment of an air conditioner of the present invention.

FIG. 2 is a Ph diagram of a heat pump cycle showing a method of determining necessity of defrosting by the control unit of FIG. 1.

FIG. 3 is a refrigerant circuit diagram showing a conventional air conditioner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Control part, 11 ... Compressor, 12 ... Four-way switching valve, 13 ...
Outdoor heat exchanger, 14 ... outdoor fan, 15 ... expansion valve, 16
a to 16d ... Indoor heat exchanger, 17a to 17f ... Pipe line, 23 ...
Liquid receiver, 25 ... First on-off valve, 26 ... Defrost pipe line, 2
7 ... 2nd on-off valve, 28 ... Pipe line, 29 ... Capillary tube, 30 ... Flow divider, 31 ... 1st refrigerant temperature sensor, 32 ...
2nd refrigerant temperature sensor, 33 ... Heat exchanger temperature sensor, 34
... outside temperature sensor.

Claims (1)

[Claims] 1. A compressor (11), an outdoor heat exchanger (13) capable of operating as an evaporator, an expansion valve (15), and an indoor heat exchanger (16a-16d) capable of operating as a condenser, in sequence.
(17a to 17f), and connect the compressor (1
1) The first refrigerant temperature sensor (31) for detecting the temperature (Da) of the refrigerant sucked into 1) and the saturation temperature of the refrigerant corresponding to the low pressure
The heat pump type refrigerant circuit provided with the second refrigerant temperature sensor (32) for detecting (De) and the detection signals of the first and second refrigerant temperature sensors (31, 32) are set to have a predetermined value. In an air conditioner equipped with a control unit (1) for controlling the opening of an expansion valve (15) and the number of revolutions of a compressor (11), an outside air temperature sensor (34) for detecting the temperature of outside air and the outdoor heat A single heat exchanger temperature sensor (33) that detects the temperature of the exchanger, an outside air temperature sensor (34) and a heat exchanger temperature sensor during operation.
The difference between the outside air temperature (Do) and the outdoor heat exchanger temperature (Dc) is obtained based on both detection signals of (33) and it is determined whether or not this difference (Do-Dc) is less than a certain value (α). When the non-uniform flow determination means (1) and the non-uniform flow determination means (1) determine that the result is positive, instead of the detection signal of the heat exchanger temperature sensor (33), the detection signal of the second refrigerant temperature sensor (32) When the temperature (De) represented by is below a certain value (β), it is determined as positive,
An air conditioner comprising defrosting control starting means (1) for starting control for defrosting the outdoor heat exchanger (13).