Patent Application
20200200406
The present invention relates to an outdoor unit of an air-conditioning apparatus applied, for example, to a variable refrigerant flow system.
An outdoor unit of an air-conditioning apparatus has an outer shell having, for example, a cuboid shape, and in consideration of maintainability, a heat exchanger is disposed along three side surfaces among four side surfaces excluding a side surface used for maintenance work (see, for example, Patent Literature 1). In the outdoor unit of Patent Literature 1, a control box for controlling devices contained in the outdoor unit is disposed in an upper part of an inside of a housing of the outdoor unit and disposed opposite the side surface used for maintenance work.
Patent Literature 1: International Publication No. 2014/196569
One measure to increase heat-exchange capability in an outdoor unit is to increase the number of surfaces along which a heat exchanger is disposed, specifically, dispose a heat exchanger along all of four side surfaces. In a case where the heat exchanger is disposed in this manner, there is no space where a control box, which needs to be accessed from an outside of a housing, is disposed. To solve this problem, a configuration may be conceived in which a heat exchanger is disposed along all of four side surfaces in an upper part of an inside of a housing and a control box is disposed in a lower part of the inside of the housing.
An air-conditioning apparatus performs defrosting operation for melting frost generated on a heat exchanger during heating operation in winter. As a result of the defrosting operation, water (hereinafter referred to as defrost water) molten by the defrosting operation flows down onto a base that constitutes a bottom surface of a housing. In a case where a control box is disposed in a lower part of an inside of the housing, the defrost water that flows down from the heat exchanger during the defrosting operation is accumulated on the base, and a bottom part of the control box is immersed in the accumulated defrost water. Because of the possible immersion, electric leakage may be undesirably caused. For this reason, it is necessary to take a countermeasure against such inconvenience in a case where a control box is disposed below a heat exchanger. However, in Patent Literature 1, as only a configuration is considered in which a controller is disposed in an upper part of an inside of a housing, the countermeasure against such immersion is not taken at all.
The present invention has been accomplished to solve the above problem, and an object of the present invention is to provide an outdoor unit of an air-conditioning apparatus in which a control box is disposed below a heat exchanger and the control box is less likely to be immersed in water.
An outdoor unit of an air-conditioning apparatus according to an embodiment of the present invention includes a housing, a heat exchanger provided in an upper part of an inside of the housing, and a control box disposed in the housing and configured to control the outdoor unit. The housing includes a base on which the control box is disposed and that is provided with a water drainage groove and a water drainage hole for draining defrost water generated on the heat exchanger to an outside, the base has three surfaces located at different heights that are, in order from top, a first surface, a second surface, and a third surface that is a bottom surface of the water drainage groove and is provided with the water drainage hole, and the control box is disposed on the first surface.
According to an embodiment of the present invention, a base on which a control box is provided has three surfaces that are located at different heights, and the control box is disposed on a first surface located at the highest position among the three surfaces. This configuration can make it less likely that the control box be immersed in water.
Embodiments of the present invention are described below with reference to the drawings.
In Embodiment 1, for example, defrost water generated during defrosting operation of a variable refrigerant flow system is received by a base provided below a heat exchanger. Consequently, electric leakage caused by the defrost water is made less likely to occur.
As illustrated in
The outdoor unit 10 includes a compressor 11, a flow switching device 12 such as a four-way valve, an outdoor-side heat exchanger 13, an accumulator 15, and an outdoor-side fan (not illustrated) that supplies air to the outdoor-side heat exchanger 13. The compressor 11 is, for example, an inverter compressor whose capacity can be controlled. The compressor 11 suctions low-temperature low-pressure gas refrigerant, compresses the gas refrigerant into high-temperature high-pressure gas refrigerant, and discharges the high-temperature high-pressure gas refrigerant. The flow switching device 12 switches between flow of refrigerant during a heating operation mode and flow of refrigerant during a cooling operation mode or defrosting operation.
The outdoor-side heat exchanger 13 includes an outdoor-side heat exchanger 13a and an outdoor-side heat exchanger 13b, each of which has, for example, an L-shape. A corner of the outdoor-side heat exchanger 13a and a corner of the outdoor-side heat exchanger 13b are disposed diagonally opposite to each other and thus the outdoor-side heat exchanger 13a and the outdoor-side heat exchanger 13b constitute a quadrangular heat exchanger. In this case, an outdoor-side fan is disposed above the outdoor-side heat exchanger 13. Furthermore, a machine room in which components such as the compressor 11, the flow switching device 12, and the accumulator 15 are disposed is provided below the outdoor-side heat exchanger 13. Furthermore, the machine room is provided with a front panel that is opened and closed for maintenance.
The outdoor-side heat exchanger 13 is used as an evaporator during a heating operation mode and is used as a condenser during a cooling operation mode and a defrosting operation mode. The outdoor-side heat exchanger 13 exchanges heat between air sent by the outdoor-side fan and refrigerant. The accumulator 15 is provided to an intake port of the compressor 11 and accumulates in the accumulator 15 excess refrigerant that is generated because of a difference between the heating operation mode and the cooling operation mode and excess refrigerant that is generated in transition of operation.
A bypass 18 is provided in the outdoor unit 10. The bypass 18 includes a first bypass pipe 18a, a second bypass pipe 18b, a third bypass pipe 18c, and a fourth bypass pipe 18d. Note that detailed description of the configuration of the bypass 18 and description of flow of refrigerant in the bypass 18 are omitted as the bypass 18 is irrelevant to the gist of the present invention.
The first bypass pipe 18a branches from a refrigerant pipe 16 between the compressor 11 and the flow switching device 12. The second bypass pipe 18b branches from the first bypass pipe 18a and is connected to one end of a heat transfer tube 13aa of the outdoor-side heat exchanger 13a and one end of a heat transfer tube 13ba of the outdoor-side heat exchanger 13b. The third bypass pipe 18c is pipes whose one ends are each connected to the corresponding one of the other end of the heat transfer tube 13aa and the other end of the heat transfer tube 13ba and whose other ends merge with each other. The fourth bypass pipe 18d branches from a refrigerant pipe 17 between the flow switching device 12 and the accumulator 15 and is connected to a merging point of the third bypass pipe 18c. A valve opening-closing device 19 is attached to the fourth bypass pipe 18d. The valve opening-closing device 19 is, for example, a solenoid valve.
The indoor units 20 include four indoor-side heat exchangers 21, expansion devices 22 that are each connected in series with the corresponding one of the four indoor-side heat exchangers 21, and an indoor-side fan (not illustrated) that supplies air to each of the indoor-side heat exchangers 21. Each of the indoor-side heat exchangers 21 is used as a condenser during a heating operation mode and is used as an evaporator during a cooling operation mode. Each of the indoor-side heat exchangers 21 exchanges heat between air supplied by the indoor-side fan and refrigerant and supplies cooling air or heating air to a space to be air-conditioned. Each of the expansion devices 22 is used as a pressure reducing valve or an expansion valve and expands refrigerant by reducing a pressure of the refrigerant. Each of the expansion devices 22 is, for example, an electronic expansion valve whose valve opening degree can be controlled.
Next, operation of the air-conditioning apparatus according to Embodiment 1 is described.
When the compressor 11 is driven, low-temperature low-pressure gas refrigerant flows into the compressor 11 and is compressed into high-temperature high-pressure gas refrigerant, and the high-temperature high-pressure gas refrigerant is discharged. The high-temperature high-pressure gas refrigerant discharged from the compressor 11 flows out from the outdoor unit 10 by passing through the flow switching device 12 and flows into each of the indoor-side heat exchangers 21 through the refrigerant pipe 30. The high-temperature high-pressure gas refrigerant that has flowed into the indoor-side heat exchangers 21 is condensed into low-temperature high-pressure liquid refrigerant by transferring heat to surrounding air through heat exchange with air supplied from the indoor-side fan, and the low-temperature high-pressure liquid refrigerant flows out from the indoor-side heat exchangers 21. The low-temperature high-pressure liquid refrigerant that has flowed out from the indoor-side heat exchangers 21 is depressurized into low-temperature low-pressure two-phase gas-liquid refrigerant by the expansion devices 22, and the low-temperature low-pressure two-phase gas-liquid refrigerant flows out from the indoor units 20.
The two-phase gas-liquid refrigerant that has flowed out from the indoor units 20 flows into the outdoor-side heat exchanger 13 of the outdoor unit 10 through the refrigerant pipe 30. The two-phase gas-liquid refrigerant that has flowed into the outdoor-side heat exchanger 13 evaporates into low-pressure gas refrigerant by receiving heat from surrounding air through heat exchange with air supplied from the outdoor-side fan, and the low-pressure gas refrigerant flows out from the outdoor-side heat exchanger 13. The gas refrigerant that has flowed out from the outdoor-side heat exchanger 13 enters the accumulator 15 through the flow switching device 12. The gas refrigerant that has entered the accumulator 15 is separated into liquid refrigerant and gas refrigerant, and the low-temperature low-pressure gas refrigerant is suctioned into the compressor 11 again. The suctioned gas refrigerant is compressed again by the compressor 11 and is then discharged. In this manner, the refrigerant is repeatedly circulated.
In a case where heating operation is continuously performed when an outside air temperature is low and where an evaporating temperature is less than or equal to 0 degrees C., frost is formed on a surface of the outdoor-side heat exchanger 13. The frost is generated because moisture included in air that exchanges heat forms dew on the surface of the outdoor-side heat exchanger 13 that receives heat as an evaporator. In a case where an amount of frost increases, thermal resistance increases, and an air volume decreases. The decrease in air volume also decreases a temperature (evaporating temperature) of the heat transfer tube of the outdoor-side heat exchanger 13. Consequently, it is impossible to fully use heating capacity. To fully use heating capacity, frost needs to be removed by defrosting operation.
In defrosting operation, normal heating operation is interrupted, and refrigerant is circulated in a direction identical to a direction in cooling operation by the flow switching device 12. In this case, low-temperature low-pressure gas refrigerant flows into the compressor 11 and is compressed into high-temperature high-pressure gas refrigerant, and the high-temperature high-pressure gas refrigerant is discharged. The high-temperature high-pressure gas refrigerant discharged from the compressor 11 flows into the outdoor-side heat exchanger 13 by passing through the flow switching device 12.
The high-temperature high-pressure gas refrigerant that has flowed into the outdoor-side heat exchanger 13 transfers heat to surrounding air through heat exchange with air supplied from the outdoor-side fan and turns into low-temperature high-pressure liquid refrigerant. The transferred heat melts frost attached to the outdoor-side heat exchanger 13. At this time, the outdoor-side fan is not operating in many cases. The low-temperature high-pressure liquid refrigerant that has flowed out from the outdoor-side heat exchanger 13 flows into the indoor units 20 through the refrigerant pipe 30.
The low-temperature high-pressure liquid refrigerant that has flowed into the indoor units 20 is depressurized into low-temperature low-pressure two-phase gas-liquid refrigerant by the expansion devices 22. The two-phase gas-liquid refrigerant flows into the indoor-side heat exchangers 21, enters the outdoor unit 10 again without heat exchange while keeping the two-phase gas-liquid state, and enters the accumulator 15 through the flow switching device 12. The refrigerant that has entered the accumulator 15 is separated into liquid refrigerant and gas refrigerant, and the low-temperature low-pressure gas refrigerant is suctioned into the compressor 11 again. The suctioned gas refrigerant is compressed again by the compressor 11 and is then discharged. In this manner, the refrigerant is repeatedly circulated.
During the defrosting operation, defrost water generated when frost attached to the outdoor-side heat exchanger 13 melts drops and flows down through a fin of the outdoor-side heat exchanger 13 onto the base 2 (see
As illustrated in
As described above, the outdoor-side heat exchanger 13a and the outdoor-side heat exchanger 13b each having an L-shape are combined to constitute the outdoor-side heat exchanger 13 having a substantially square shape, and an outer side surface of the outdoor-side heat exchanger 13 is disposed along an inner side surface of the housing 1 although illustration of details of the outdoor-side heat exchanger 13 is omitted. The outdoor-side heat exchanger 13 is supported in an upper part of an inside of the housing 1 by a support table (not illustrated) provided in the housing 1.
The housing 1 includes frame parts 3 that each extend upward from the corresponding one of corners of the base 2 provided on the bottom surface. The housing 1 has, on an upper part of an outer peripheral surface of the housing 1 surrounded by the frame parts 3, air inlets 1a for suctioning air into the housing 1, and the outdoor-side heat exchanger 13 is disposed along the air inlets 1a. The housing 1 has an air outlet 1b in an upper surface of the housing 1, and the outdoor-side fan 4 is disposed directly below the air outlet 1b in the housing 1. When the outdoor-side fan 4 is driven, air suctioned into the housing 1 from the air inlets 1a exchanges heat with refrigerant by passing through the outdoor-side heat exchanger 13 and then the air is discharged from the air outlet 1b through the outdoor-side fan 4.
The housing 1 is provided with side panels 5 that are each a design plate. The side panels 5 are disposed in a lower part of the outer peripheral surface of the housing 1 surrounded by the frame parts 3 and seal openings at the lower portion of the housing 1. Left and right edges of each of the side panels 5 are each fixed to the corresponding one of the frame parts 3 with use of a fastening part such as a screw, and a lower edge of each of the side panels 5 is fixed to the base 2 with use of a fastening part such as a screw.
The inner lower part of the housing 1 is a machine room. In the machine room, components such as the compressor 11 and the control box 40 are disposed on the base 2 as illustrated in
A large amount of defrost water is generated in a high-humidity environment as the defrosting operation is performed at a cycle of approximately one time per hour. In a case where the defrost water continues to flow onto the base 2 and is not sufficiently drained, there is a risk of immersion of the control box 40 in the water and a risk of freezing of the defrost water and growth of ice in a case where the operation switches to heating operation before the water is sufficiently drained.
In view of the risks, in Embodiment 1, the control box 40 is made less likely to be immersed in water by specifying a base structure on which the control box 40 is provided and a position where the control box 40 is disposed. This configuration is described below.
The base 2 has a substantially rectangular shape and has the water drainage holes 50 that drain, to an outside, defrost water that has flowed down from the outdoor-side heat exchanger 13 onto the base 2 during the defrosting operation and water drainage grooves 51 that guide the defrost water to the water drainage holes 50.
The base 2 is provided with ribs having different heights so that structural strength is obtained and has a plurality of surfaces located at different heights accordingly. Specifically, as illustrated in
In Embodiment 1, the control box 40, which is disposed on the base 2 as described above, is disposed especially on the topmost surface 2b of the base 2. With this configuration, the control box 40 is less likely to be immersed in defrost water. A region where the control box 40 is disposed on the topmost surface 2b is surrounded by the water drainage surface 2c. That is, the water drainage surface 2c located at a height lower than the region where the control box 40 is disposed is provided around the region where the control box 40 is disposed. As defrost water is accumulated in a part around the control box 40, the control box 40 is further less likely to be immersed in the defrost water.
Furthermore, durability can be improved by also disposing a heavy device such as a compressor on the topmost surface 2b and specifying an area of this topmost surface 2b to a minimum area having strength with which the weight of the device can be supported.
Next, specifications of a width and a depth of each of the water drainage grooves 51 and a length of a water drainage path that are for improving water drainage performance are described. The base 2 is not limited to the shape and the size illustrated in
A width w and a depth h of each of the water drainage grooves 51 are specified so that defrost water is not frozen while the defrost water is flowing through the water drainage grooves 51. The width w of each of the water drainage grooves 51, that is, the width w of each part of the water drainage surface 2c is specified to less than or equal to 22 mm on the basis of a heat capacity of the base 2 and an outside air temperature to reduce heat transfer of water. A dehumidification water amount can be obtained from a horsepower of the outdoor unit 10, the number of surfaces along which the outdoor-side heat exchanger 13 is disposed, and an area of a front surface of the outdoor-side heat exchanger 13. When a total amount of defrost water generated in the outdoor unit 10 that has an 18 horsepower and four surfaces along which the outdoor-side heat exchanger 13 is disposed is 3.5 kg, an amount of water per surface is approximately 0.9 kg in one defrosting operation. During defrosting control, defrost water flows down uniformly from the whole outdoor-side heat exchanger 13, and empirically, approximately three minutes to six minutes are required for the defrost water to flow down from the outdoor-side heat exchanger 13 and be drained to an outside. The depth of each of the water drainage grooves 51 is designed in view of these factors and in consideration of the length of each of the water drainage grooves 51, which will be described later.
In a case where the length of the water drainage path, that is, the water drainage grooves 51 are too long, defrost water is more likely to be frozen before the defrost water is drained to an outside. For this reason, the length of the water drainage grooves 51, specifically, an interval 11 (see
Furthermore, as it is important to drain defrost water flowing through the water drainage grooves 51 from the water drainage holes 50 as promptly as possible, the water drainage surface 2c is inclined at a gradient. The gradient is specified more than or equal to 1/50, which is also used as a construction standard of a water conduit, as an angle necessary for causing defrost water to flow. The gradient of 1/50 creates a difference in height of up to 10 mm between the water drainage holes 50 of the water drainage surface 2c. Consequently, water drainage performance is improved. Furthermore, the water drainage holes 50 around the outdoor-side heat exchanger 13 and around the refrigerant pipe on which dew is formed each have a larger diameter than a diameter of water drainage holes 50a (see
As described above, according to Embodiment 1, the base 2 has three surfaces located at different heights, and the control box 40 is disposed on the topmost surface 2b located at the highest position among the three surfaces. With this configuration, the control box 40 can be made less likely to be immersed in defrost water.
Furthermore, the region where the control box 40 is disposed is surrounded by the water drainage surface 2c that is the lowest surface among the three surfaces. With this configuration, the control box 40 can be further made less likely to be immersed in defrost water.
As defrosting operation is performed, for example, at a cycle of approximately one time per hour as described above, a large amount of defrost water is generated in a high-humidity environment. Consequently, when water drainage performance is not sufficient, there is a risk of hindering maintenance because a panel at a space for maintenance cannot be detached because of ice grown on the base 2. However, in a case where water drainage performance is improved by employing the structure and the specifications of the base 2 described above, an advantage of ensuring serviceability is also produced.
Water drainage performance of not only defrost water but also water such as rainwater and dew condensation water can be improved by employing the above structure of the base 2. Consequently, accumulation of the water and immersion of the control box 40 in water caused by freezing of the water can be made less likely to occur.
Although a shape of the control box 40 is not specified in particular in Embodiment 1, the shape of the control box 40 is specified in Embodiment 2. Differences of Embodiment 2 from Embodiment 1 are mainly described below, and matters that are not described below are similar to those in Embodiment 1.
The control box 40 includes a box part 41 having a cuboid shape and in which components such as a control substrate (not illustrated) and an inverter substrate (not illustrated) are disposed and a leg part 42 extending downward from three edges of a lower surface of the box part 41 so that a space for heat transfer and electric wire routing is defined below the box part 41. The leg part 42 has a right leg part 42a, a left leg part 42b, and a rear leg part 42c. Each of the right leg part 42a and the left leg part 42b has a part that is in contact with the topmost surface 2b of the base 2 and in which recesses 43 each through which a wire passes are located. Furthermore, the rear leg part 42c has through-holes 44 each through which a wire passes.
Defrost water that falls from above the control box 40 is present on the topmost surface 2b on which the control box 40 is provided, and a volume of each of the recesses 43 is specified to more than 0 cm3 and less than or equal to 10 cm3 to prevent the defrost water from flowing into a space below the box part 41 of the control box 40. When a water temperature of the defrost water is 1 degree C., the volume of each of the recesses 43 is specified to less than or equal to 10 g in water amount, in other words, less than or equal to 10 cm3 by considering an amount of ice that can be molten on the basis of an amount of sensible heat. By specifying the volume of each of the recesses 43 to this volume, it is possible to prevent defrost water in the recesses 43 from freezing when defrosting operation switches to heating operation and prevent defrost water from flowing into the space below the box part 41 from the recesses 43.
The space below the box part 41 is a space for electric wire routing as described above, and a large number of wires placed into the box part 41 are gathered in this space (not illustrated in
The leg part 42 is provided at right, left, and rear portions in
The control substrate and the inverter substrate disposed in the box part 41 easily generate heat while operating, and the heat is transferred to a heat transfer unit provided on the control substrate, but the heat is also transferred to air in the box part 41 in a large quantity. For this reason, it is also possible to provide a heat transfer hole (not illustrated) in a bottom surface of the box part 41 so that the heat transmitted to air in the box part 41 is transferred from the heat transfer hole to an outside of the box part 41 to prevent water that has fallen onto the base 2 from freezing or from growing as ice.
As described above, according to Embodiment 2, the following effects can be obtained in addition to effects similar to the effects of Embodiment 1. Specifically, as the leg part 42 of the control box 40 has, at a part of the leg part 42 that is in contact with the base 2, the recesses 43 each having a volume of more than 0 cm3 and less than or equal to 10 cm3, defrost water on the topmost surface 2b can be made less likely to flow into the space below the box part 41 of the control box 40. The recesses 43 each reduce an area of a surface of the leg part 42 provided on the base 2. Consequently, an effect of reducing chattering noise caused by vibration of the compressor 11 is also produced.
Embodiment 3 relates to a structure of water drainage from the outdoor-side heat exchanger 13 to the base 2. Differences of Embodiment 3 from Embodiment 1 are mainly described below, and matters that are not described below are similar to those in Embodiment 1.
As illustrated in
The water guide plate 7 is a substantially flat plate, and an upper part of the water guide plate 7 is an inclined surface 7a that faces a lower surface of the outdoor-side heat exchanger 13 and extends diagonally downward from an inner portion toward an outer portion in the housing 1, and a lower part of the water guide plate 7 is a vertical surface 7b that extends vertically downward from a lower end of the inclined surface 7a. A lower end of the water guide plate 7 is located lower than the topmost surface 2b of the base 2.
When the water guide plate 7 is not disposed, a water droplet that has fallen from the outdoor-side heat exchanger 13 is likely to be scattered onto the topmost surface 2b of the base 2 because of influence of wind or other factors. Meanwhile, in a case where the water guide plate 7 is provided, defrost water that has dropped from the outdoor-side heat exchanger 13 can be guided downward through the water drainage path 6 and be guided to the water drainage grooves 51.
As described above, according to Embodiment 3, in which the lower end of the water guide plate 7 is located lower than the topmost surface 2b, it is possible to prevent defrost water that has dropped from the outdoor-side heat exchanger 13 from scattering onto the topmost surface 2b, in addition to effects similar to effects of Embodiment 1.
1 housing 1a air inlet 1b air outlet 2 base 2a reference surface 2b topmost surface (high-level surface) 2c water drainage surface (low-level surface) 3 frame part 4 outdoor-side fan 5 side panel 6 water drainage path 7 water guide plate 7a inclined surface 7b vertical surface 10 outdoor unit 11 compressor 12 flow switching device 13 outdoor-side heat exchanger 13a outdoor-side heat exchanger 13aa heat transfer tube 13b outdoor-side heat exchanger 13ba heat transfer tube 15 accumulator 16 refrigerant pipe 17 refrigerant pipe 18 bypass 18a first bypass pipe 18b second bypass pipe 18c third bypass pipe 18d fourth bypass pipe 19 valve opening-closing device 20 indoor unit 21 indoor-side heat exchanger 22 expansion device 30 refrigerant pipe 40 control box 41 box part 42 leg part 42a right leg part 42b left leg part 42c rear leg part 43 recess 44 through-hole 45 heat transfer hole 50 water drainage hole 50a water drainage hole 51 water drainage groove 11 interval between water drainage holes 12 distance between part onto which defrost water falls and water drainage hole
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/033299 | 9/14/2017 | WO | 00 |
