WO2009150824A1

WO2009150824A1 - Refrigeration apparatus

Info

Publication number: WO2009150824A1
Application number: PCT/JP2009/002595
Authority: WO
Inventors: 原田浩一; 木戸尚宏; 寺木潤一; 田中三博
Original assignee: ダイキン工業株式会社
Priority date: 2008-06-12
Filing date: 2009-06-09
Publication date: 2009-12-17
Also published as: JP2009299986A

Abstract

In an air conditioner (10) constructed from a refrigeration apparatus, a cooling member (50) is provided between an expansion valve (43) and an outdoor heat exchanger (42) in the refrigerant path (20). The cooling member (50) cools a power element (56) provided in an inverter (55) with a refrigerant. A compressor controller (61) and an expansion valve controller (62) are provided in a controller (60) of the air conditioner (10). When the heating operation starts, the compressor controller (61) gradually raises in steps the rotational speed of the compressor (30). The expansion valve controller (62) increases the degree of opening of the expansion valve (43) each time the rotational speed of the compressor (30) is raised until the degree of opening corresponds to the rotational speed of the compressor (30), and prevents the temperature of the refrigerant flowing from the expansion valve (43) to the cooling member (50) from becoming too low.

Description

Refrigeration equipment

The present invention relates to a refrigeration apparatus that cools a power element of a power source that supplies power to a compressor with a refrigerant.

Conventionally, a refrigeration apparatus that cools a power element of a power source that supplies power to a compressor with a refrigerant is known. For example, Patent Document 1 discloses an air conditioner that is a type of refrigeration apparatus, in which a cooling unit for cooling a power element is disposed between an expansion valve and an outdoor heat exchanger in a refrigerant circuit. Has been. The air conditioner of Patent Document 1 performs a heating operation in which an indoor heat exchanger serves as a condenser and an outdoor heat exchanger serves as an evaporator. During the heating operation, the refrigerant that is depressurized by the expansion valve and directed to the outdoor heat exchanger cools the power element in the cooling unit.

Japanese Patent Laid-Open No. 03-075424

In the refrigerant circuit that performs the refrigeration cycle, the temperature of the refrigerant that is depressurized by the expansion valve and goes to the evaporator is relatively low. For this reason, if a power element is cooled with the comparatively low temperature refrigerant | coolant which goes to an evaporator from an expansion valve, the temperature of a power element can be reliably suppressed low.

However, if the temperature from the expansion valve toward the evaporator becomes too low, the temperature of the power element itself and its surroundings becomes lower than the dew point temperature of the air around the power element, and the surface of the power element and its surroundings. Condensation may occur in the part. If dew condensation occurs in such a place, there is a possibility that the electrodes of the power element, the wiring portion of the board on which the power element is installed, etc. will be corroded, or the insulation of the power element itself will be lowered.

Especially when starting up the compressor, there is a high risk of condensation on the power element and its surroundings. This point will be described with reference to FIG. As shown in the figure, at the time of starting the compressor, the rotational speed of the compressor is not increased at a stretch, but is increased stepwise in a plurality of times. Further, although the opening degree of the expansion valve gradually increases, the opening degree does not correspond to the rotational speed of the compressor that is gradually increased. On the other hand, when the rotational speed of the compressor increases, the current flowing through the power element increases and the amount of heat generated in the power element also increases. However, since the power element itself has a certain amount of heat capacity, the rotational speed of the compressor is increased. There is a certain time difference until the temperature of the power element starts to rise. For this reason, immediately after the rotational speed of the compressor is increased, the temperature of the power element and its peripheral portion is rather lowered due to the increase in the flow rate of the refrigerant, which may cause condensation.

The present invention has been made in view of the above points, and an object of the present invention is to provide a refrigeration apparatus that cools a power element of a power source that supplies power to a compressor with a refrigerant, in which dew condensation is not caused in the power element and its peripheral portion. It is to prevent and improve the reliability of the refrigeration system.

1st invention has the refrigerant circuit (20) which connects a compressor (30) and an expansion valve (43), and performs a refrigerating cycle, and the electric motor of the said compressor (30) which has a power element (56) (33) disposed between the expansion valve (43) and the evaporator (42) in the refrigerant circuit (20) by the power source (55) for supplying power to the refrigerant circuit (20), and the refrigerant in the refrigerant circuit (20) A refrigeration apparatus including a cooling member (50) for cooling a power element (56) of a power source (55) is a target. And, when starting the compressor (30), the opening degree of the expansion valve (43) is set to an opening degree determined based on the rotational speed of the compressor (30). The control means (60) which performs is provided.

In the first invention, the cooling member (50) is provided between the expansion valve (43) and the evaporator (42) in the refrigerant circuit (20). In the cooling member (50), the refrigerant that is decompressed by the expansion valve (43) and goes to the evaporator (42) absorbs heat from the power element (56) provided in the power source (55). When starting the compressor (30), the control means (60) performs an expansion valve control operation for starting. In this expansion valve control operation, the control means (60) sets the opening of the expansion valve (43) to an opening determined based on the rotational speed of the compressor (30). That is, when starting the compressor (30), the opening degree of the expansion valve (43) is set to an opening degree corresponding to the rotational speed of the compressor (30) at that time.

In a second aspect based on the first aspect, the control means (60) sets the rotational speed of the compressor (30) to a predetermined target rotational speed when starting the compressor (30). In addition to performing a starting compressor control operation that pulls up in stages, the operation of increasing the opening of the expansion valve (43) every time the rotational speed of the compressor (30) is increased in the compressor control operation This is performed as an expansion valve control operation.

In the second invention, the control means (60) performs the startup compressor control operation and the startup expansion valve control operation in parallel when the compressor (30) is started. In the starting compressor control operation, the control means (60) raises the rotational speed of the started compressor (30) stepwise rather than at a stretch to a predetermined target rotational speed. In the expansion valve control operation performed in parallel with the compressor control operation, the control means (60) increases the opening of the expansion valve (43) every time the rotational speed of the compressor (30) is increased. Go. When the opening degree of the expansion valve (43) increases in conjunction with the increase in the rotational speed of the compressor (30), the pressure before and after the expansion valve (43) due to the increase in the rotational speed of the compressor (30) The expansion of the difference is suppressed.

In a third aspect based on the first aspect, the control means (60) is configured to open the opening of the expansion valve (43) in conjunction with the start of the compressor (30) at the start of the expansion valve control operation. Is increased at a stretch to a predetermined opening degree.

In a fourth aspect based on the second aspect, the control means (60) is configured to open the opening of the expansion valve (43) in conjunction with the start of the compressor (30) at the start of the expansion valve control operation. Is increased at a stretch to a predetermined opening degree.

The control means (60) of each of the third and fourth aspects of the invention is configured so that, in the expansion valve control operation for start-up, the opening of the expansion valve (43) is interlocked with the start-up of the compressor (30). Increase at a stretch. That is, when the compressor (30) is activated and the refrigerant begins to pass through the expansion valve (43), the opening of the expansion valve (43) is already set to the opening at the time of activation.

According to a fifth invention, in any one of the first to fourth inventions, the power element (56), the cooling member (50), or the power element (56) is installed in the vicinity of the dew condensation. A dew condensation sensor (70) for detecting occurrence is provided, and the control means (60) opens the expansion valve (43) when the dew condensation sensor (70) detects the occurrence of dew condensation after the expansion valve control operation is completed. The operation of forcibly increasing the degree is performed.

In the refrigeration apparatus (10) of the fifth invention, the dew condensation sensor (70) for detecting the occurrence of dew condensation is installed in the vicinity of the power element (56), the cooling member (50), or the power element (56). . When the dew condensation sensor (70) detects the occurrence of dew condensation around the power element (56), cooling member (50), or power element (56) after the start-up expansion valve control operation is completed, The means (60) forcibly increases the opening degree of the expansion valve (43). When the opening degree of the expansion valve (43) increases, the pressure difference between both sides of the expansion valve (43) decreases, and the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) increases.

In a sixth aspect of the present invention, in any one of the first to fourth aspects of the invention, a physical quantity serving as an index for the possibility of condensation on the surface of the power element (56) or the cooling member (50) is measured. Measuring means (71 to 74), and the control means (60), after the end of the expansion valve control operation, based on the measured value of the measuring means (71 to 74), the power element (56) or the cooling device If it is determined that there is a high possibility that condensation will occur on the surface of the member (50), the opening of the expansion valve (43) is forcibly increased.

In the sixth invention, the measurement means (71 to 74) measure a predetermined physical quantity and input the obtained measurement value to the control means (60). After the start-up expansion valve control operation is completed, the control means (60) uses the measured values of the measuring means (71 to 74) to cause condensation on the surface of the power element (56) and the cooling member (50). It is determined whether or not there is a high possibility of occurrence, and if it is determined that the possibility is high, the opening of the expansion valve (43) is forcibly increased. When the opening degree of the expansion valve (43) increases, the pressure difference between both sides of the expansion valve (43) decreases, and the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) increases.

In the present invention, the control means (60) performs the start-up expansion valve control operation when starting the compressor (30), and sets the opening of the expansion valve (43) of the compressor (30) at that time. Set the opening according to the rotation speed. For this reason, the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) is low while the opening of the expansion valve (43) remains small despite the increase in the rotational speed of the compressor (30). It is possible to avoid a situation in which it becomes too much, and as a result, it is possible to prevent troubles caused by condensation on the power element (56) and its peripheral portion.

In the second aspect of the invention, when the compressor (30) is started, the control means (60) performs the start-up compressor control operation and the start-up expansion valve control operation in parallel. That is, at the time of starting the compressor (30), the control means (60) increases the opening degree of the expansion valve (43) every time the rotational speed of the compressor (30) is increased. For this reason, the expansion of the pressure difference before and after the expansion valve (43) due to the increase in the rotational speed of the compressor (30) is suppressed, and the temperature drop of the refrigerant supplied to the cooling member (50) is reduced. Is done. Therefore, according to this invention, the situation where the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) becomes too low can be avoided, and the power element (56) cooled by the cooling member (50) can be avoided. ) And its surroundings can be reliably prevented.

Here, when the compressor (30) that has been stopped is started, if the opening of the expansion valve (43) is too small, the pressure difference between the two sides of the expansion valve (43) will rapidly increase, causing expansion. There is a possibility that the temperature of the refrigerant sent from the valve (43) to the cooling member (50) may rapidly decrease.

On the other hand, the control means (60) of each of the third and fourth inventions starts the expansion valve (43) in conjunction with the activation of the compressor (30) when starting the expansion valve control operation for activation. ) Is increased at a stretch to the opening at startup. For this reason, when the compressor (30) is activated and the refrigerant begins to pass through the expansion valve (43), the opening of the expansion valve (43) is already set to the opening at the time of activation, and the expansion valve (43) Since the expansion of the pressure difference between the two sides of the refrigerant is alleviated, the amount of decrease in the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) is reduced.

In the fifth invention, when the dew condensation sensor (70) detects the occurrence of dew condensation in the periphery of the power element (56), the cooling member (50), or the power element (56), the control means (60) Forcibly increase the opening of the expansion valve (43). In the sixth invention, the control means (60) may cause condensation on the surfaces of the power element (56) and the cooling member (50) based on the measurement values of the measurement means (71 to 74). If it is determined that the value is high, the opening of the expansion valve (43) is forcibly increased. When the opening degree of the expansion valve (43) increases, the pressure difference between both sides of the expansion valve (43) decreases, and the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) increases. Therefore, according to each of the fifth and sixth inventions, after the start of the compressor (30) is completed and the normal operation state is reached, the cooling member (50) and the power element (56) are excessively moved. Can be prevented, and troubles due to condensation on the surfaces of the power element (56) and the cooling member (50) can be prevented.

It is a refrigerant circuit figure which shows schematic structure of the air conditioner of Embodiment 1. It is an enlarged view which shows the principal part of the inverter apparatus of Embodiment 1, and the member for cooling. It is a graph which shows the time change of (A) the temperature of the member for cooling, (B) the opening degree of an expansion valve, and (C) the rotational speed of a compressor at the time of starting of the compressor of Embodiment 1. It is a flowchart which shows the control operation for condensation prevention which the expansion valve control part of the controller of Embodiment 1 performs. It is an enlarged view which shows the principal part of the inverter apparatus of Embodiment 2, and the member for cooling. FIG. 6 is a flowchart showing a dew prevention control operation performed by an expansion valve control unit of a controller according to a second embodiment. It is a flowchart which shows the control operation for condensation prevention which the expansion valve control part of the controller of Embodiment 3 performs. It is a flowchart which shows the control operation for dew condensation prevention which the expansion valve control part of the controller of Embodiment 4 performs. It is an enlarged view which shows the principal part of the inverter apparatus of Embodiment 5, and the member for cooling. FIG. 10 is a flowchart illustrating a dew condensation prevention control operation performed by an expansion valve control unit of a controller according to a fifth embodiment. It is a graph which shows the time change of (A) the temperature of the member for cooling, (B) the opening degree of an expansion valve, and (C) the rotational speed of a compressor at the time of starting of the conventional compressor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the Invention
A first embodiment of the present invention will be described. The present embodiment is an air conditioner (10) configured by a refrigeration apparatus.

As shown in FIG. 1, the air conditioner (10) of the present embodiment includes an outdoor unit (11) installed outdoors and an indoor unit (12) installed indoors. An outdoor circuit (21) is accommodated in the outdoor unit (11). An indoor circuit (22) is accommodated in the indoor unit (12). In the air conditioner (10), the refrigerant circuit (20) is formed by connecting the outdoor circuit (21) and the indoor circuit (22) by a pair of connecting pipes (23, 24).

The outdoor circuit (21) is provided with a compressor (30), a four-way switching valve (41), a cooling member (50), and an expansion valve (43). The cooling member (50) will be described later. The compressor (30) has its discharge side connected to the first port of the four-way switching valve (41), and its suction side connected to the second port of the four-way switching valve (41) via the accumulator (34). Yes. The four-way switching valve (41) has a third port connected to one end of the outdoor heat exchanger (42), and a fourth port connected to the gas-side closing valve (44). The other end of the outdoor heat exchanger (42) is connected to one end of the expansion valve (43) via a cooling member (50). The other end of the expansion valve (43) is connected to the liquid side closing valve (45).

The indoor circuit (22) is provided with an indoor heat exchanger (46). The indoor circuit (22) has its gas side end connected to the gas side shutoff valve (44) via the gas side connection pipe (23), and its liquid side end connected to the liquid side connection pipe (24). And is connected to the liquid side closing valve (45).

The compressor (30) is a so-called hermetic compressor. That is, in the compressor (30), the compression mechanism (32) for compressing the refrigerant and the electric motor (33) for rotationally driving the compression mechanism (32) are accommodated in one casing (31). . The four-way switching valve (41) includes a first state (state indicated by a solid line in FIG. 1) in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other. The mode is switched to a second state (state indicated by a broken line in the figure) in which the port communicates with the fourth port and the second port communicates with the third port. The expansion valve (43) is a variable opening electric expansion valve whose valve body is driven by a pulse motor.

The outdoor heat exchanger (42) and the indoor heat exchanger (46) are both fin-and-tube heat exchangers for exchanging heat between the refrigerant and air. The outdoor heat exchanger (42) exchanges heat between the outdoor air and the refrigerant. The outdoor unit (11) is provided with an outdoor fan (13) for sending outdoor air to the outdoor heat exchanger (42). The indoor heat exchanger (46) exchanges heat between the indoor air and the refrigerant. The indoor unit (12) is provided with an indoor fan (14) for sending room air to the indoor heat exchanger (46).

The outdoor unit (11) is provided with an inverter device (55) as a power source and a controller (60) as a control means. The inverter device (55) converts the AC frequency supplied from the commercial power source into a command value from the controller (60), and supplies the AC converted frequency to the motor (33) of the compressor (30). It is configured. The inverter device (55) is provided with a power element (56) such as an IGBT (Insulated Gate Bipolar Transistor). As shown in FIG. 2, in the inverter device (55), the power element (56) is attached to the wiring board (57) from the lower side.

As shown in FIG. 2, the cooling member (50) includes a main body (51) made of a metal having high thermal conductivity such as aluminum, and a refrigerant pipe (52) embedded in the main body (51). ing. The main body (51) is formed in a slightly thick flat plate shape and is attached to the power element (56) from below. That is, the upper surface of the main body (51) is in close contact with the lower surface of the power element (56). In the outdoor circuit (21), the refrigerant pipe (52) of the cooling member (50) is connected between the outdoor heat exchanger (42) and the expansion valve (43). The refrigerant flowing through the refrigerant pipe (52) absorbs heat from the power element (56) through the main body (51).

The controller (60) is provided with a compressor controller (61) and an expansion valve controller (62). The compressor control unit (61) is configured to adjust the rotational speed of the compressor (30) (that is, the rotational speed of the compression mechanism (32) driven by the electric motor (33)). The compressor controller (61) adjusts the output frequency of the inverter device (55) so that the rotational speed of the compressor (30) becomes a control target value. When the output frequency of the inverter changes, the frequency of the alternating current input to the electric motor (33) of the compressor (30) changes, and the rotational speed of the electric motor (33) that drives the compression mechanism (32) changes. The expansion valve control unit (62) adjusts the opening degree of the expansion valve (43) by driving the pulse motor of the expansion valve (43) to move the valve body.

The air conditioner (10) of the present embodiment is provided with an outdoor air temperature sensor (71), an indoor air temperature sensor (72), and a dew condensation sensor (70). The outdoor air temperature sensor (71) is provided in the outdoor unit (11) and measures the temperature of the outdoor air before passing through the outdoor heat exchanger (42) (see FIG. 1). The indoor air temperature sensor (72) is provided in the indoor unit (12) and measures the temperature of the indoor air before passing through the indoor heat exchanger (46) (see FIG. 1). The dew condensation sensor (70) is attached to the surface of the main body (51) of the cooling member (50) (more specifically, the surface in contact with the power element (56)), and the surface of the main body (51) The presence / absence of dew condensation is detected (see FIG. 2). The outputs of these sensors (70, 71, 72) are input to the controller (60).

-Driving operation-
The air conditioner (10) of the present embodiment selectively performs a cooling operation, a heating operation, and a defrosting operation.

The cooling operation will be described. In the air conditioner (10) during the cooling operation, the four-way switching valve (41) is set to the first state (the state indicated by the solid line in FIG. 1), and the outdoor fan (13) and the indoor fan (14) are operated. In the refrigerant circuit (20) during the cooling operation, a refrigeration cycle is performed. At that time, the outdoor heat exchanger (42) operates as a condenser, and the indoor heat exchanger (46) operates as an evaporator.

In the refrigerant circuit (20) during the cooling operation, the refrigerant discharged from the compressor (30) flows into the outdoor heat exchanger (42) through the four-way switching valve (41), and dissipates heat to the outdoor air to condense. To do. The refrigerant condensed in the outdoor heat exchanger (42) flows into the refrigerant pipe (52) of the cooling member (50) and absorbs heat from the power element (56) while passing through the refrigerant pipe (52). The refrigerant flowing out of the cooling member (50) is decompressed when passing through the expansion valve (43), then flows into the indoor heat exchanger (46), absorbs heat from the indoor air, and evaporates. The indoor unit (12) supplies the air cooled in the indoor heat exchanger (46) to the room. The refrigerant evaporated in the indoor heat exchanger (46) sequentially passes through the four-way switching valve (41) and the accumulator (34), and then is sucked into the compressor (30) and compressed.

The heating operation will be described. In the air conditioner (10) during the heating operation, the four-way switching valve (41) is set to the second state (the state indicated by the broken line in FIG. 1), and the outdoor fan (13) and the indoor fan (14) are operated. In the refrigerant circuit (20) during the heating operation, a refrigeration cycle is performed. At that time, the indoor heat exchanger (46) operates as a condenser, and the outdoor heat exchanger (42) operates as an evaporator. In the refrigerant circuit (20) during the heating operation, the cooling member (50) is located between the expansion valve (43) and the outdoor heat exchanger (42) that is an evaporator.

In the refrigerant circuit (20) during the heating operation, the refrigerant discharged from the compressor (30) flows into the indoor heat exchanger (46) through the four-way switching valve (41) and dissipates heat to the indoor air. Condensate. The indoor unit (12) supplies the air heated in the indoor heat exchanger (46) to the room. The refrigerant condensed in the indoor heat exchanger (46) is decompressed when passing through the expansion valve (43), then flows into the refrigerant pipe (52) of the cooling member (50), and passes through the refrigerant pipe (52). During this time, heat is absorbed from the power element (56). The refrigerant that has flowed out of the cooling member (50) flows into the outdoor heat exchanger (42), absorbs heat from the outdoor air, and evaporates. The refrigerant evaporated in the outdoor heat exchanger (42) sequentially passes through the four-way switching valve (41) and the accumulator (34), and then is sucked into the compressor (30) and compressed.

The defrosting operation will be described. The defrosting operation is performed each time the duration of the heating operation reaches a predetermined value, for example, in order to melt the frost attached to the outdoor heat exchanger (42) during the heating operation. In the air conditioner (10) during the defrosting operation, the four-way switching valve (41) is set to the first state (the state indicated by the solid line in FIG. 1) as in the cooling operation. However, in the air conditioner (10) during the defrosting operation, the outdoor fan (13) and the indoor fan (14) are stopped.

In the refrigerant circuit (20) during the defrosting operation, the refrigerant discharged from the compressor (30) flows into the outdoor heat exchanger (42), and the frost attached to the outdoor heat exchanger (42) is heated by the refrigerant. To melt. The refrigerant that has dissipated heat in the outdoor heat exchanger (42) sequentially passes through the cooling member (50), the expansion valve (43), and the indoor heat exchanger (46), and is then sucked into the compressor (30) and compressed. Is done.

-Control operation of compressor control unit-
The control operation performed by the compressor control unit (61) of the controller (60) will be described. The compressor control unit (61) performs a start-up compressor control operation, which is a start-time compressor control operation, and a normal-time compressor control operation. The compressor control unit (61) performs a start-up compressor control operation from when the compressor (30) is started until a predetermined end condition is satisfied, and when the end condition is satisfied, the start-up compressor control is performed. End the operation and start the normal compressor control operation. The compressor control unit (61) performs a start-up compressor control operation and a normal-time compressor control operation regardless of whether the air conditioner (10) performs a cooling operation or a heating operation.

The startup compressor control operation will be described with reference to FIG. Compressor control section (61) performs when you start the compressor (30), the startup compressor control operation during the period from the time t ₀ to time t ₁ when a predetermined time has elapsed at time t ₀ in FIG. That is, in the compressor control unit (61) of the present embodiment, the end condition is that the elapsed time from when the compressor (30) is started reaches a predetermined value. Compressor control unit at the time in the compressor control operation starts (61), as the rotational speed of the compressor (30) becomes a predetermined target rotational speed at the time t _1, the stage the rotation speed of the compressor (30) Gradually increase. That is, the compressor control unit (61) sets the output frequency of the inverter device (55) so that the rotational speed of the electric motor (33) that drives the compression mechanism (32) of the compressor (30) increases stepwise. Gradually raise in multiple stages.

The normal compressor control operation will be described. The compressor control unit (61) during the normal-time compressor control operation adjusts the output frequency of the inverter device (55) so that the rotational speed of the compressor (30) becomes a value corresponding to the indoor air conditioning load. . Specifically, the compressor control unit (61) adjusts the rotational speed of the compressor (30) based on the difference between the measured value of the indoor air temperature sensor (72) and the set temperature. During the cooling operation, the compressor controller (61) increases the rotational speed of the compressor (30) if the measured value of the indoor air temperature sensor (72) exceeds the set temperature, and the indoor air temperature sensor (72) If the measured value is below the set temperature, the rotational speed of the compressor (30) is reduced. In addition, during the heating operation, the compressor control unit (61) increases the rotational speed of the compressor (30) if the measured value of the indoor air temperature sensor (72) is lower than the set temperature, and the indoor air temperature sensor (72 ) If the measured value exceeds the set temperature, the rotational speed of the compressor (30) is reduced.

-Control action of expansion valve controller-
The control operation performed by the expansion valve control unit (62) of the controller (60) will be described. The expansion valve control unit (62) performs a startup expansion valve control operation, which is a startup expansion valve control operation, a normal expansion valve control operation, and a dew condensation prevention control operation.

The expansion valve control unit (62) performs the normal expansion valve control operation even when the air conditioner (10) is performing either the cooling operation or the heating operation. On the other hand, the expansion valve control unit (62) performs the startup expansion valve control operation and the dew condensation prevention control operation only when the air conditioner (10) performs the heating operation. Further, in a state where the compressor control unit (61) is performing the startup compressor control operation during the heating operation of the air conditioner (10), the expansion valve control unit (62) performs only the startup expansion valve control operation. Do. In addition, when the compressor control unit (61) performs the normal compressor control operation during the heating operation of the air conditioner (10), the expansion valve control unit (62) performs the normal expansion valve control operation and the dew condensation. Control action for prevention is performed.

Here, the reason why the expansion valve control unit (62) performs the startup expansion valve control operation and the dew condensation prevention control operation only when the air conditioner (10) performs the heating operation will be described.

As described above, in the refrigerant circuit (20) during the heating operation, the refrigerant decompressed when passing through the expansion valve (43) flows into the refrigerant pipe (52) of the cooling member (50). For this reason, when the humidity of outdoor air is high or the temperature of the refrigerant flowing into the cooling member (50) is too low, condensation may occur on the surfaces of the cooling member (50) and the power element (56). is there. Therefore, the expansion valve control unit (62) performs a startup expansion valve control operation and a dew condensation prevention control operation to prevent condensation on the surfaces of the cooling member (50) and the power element (56).

On the other hand, as described above, in the refrigerant circuit (20) during the cooling operation, the refrigerant from the outdoor heat exchanger (42), which is a condenser, to the expansion valve (43) flows into the refrigerant pipe (52 of the cooling member (50)). ). The temperature of the refrigerant flowing out of the outdoor heat exchanger (42) during the cooling operation is always higher than the temperature of the outdoor air, so that the temperature of the cooling member (50) is lower than the dew point temperature of the outdoor air. There is no possibility of condensation on the surface of the cooling member (50) or the power element (56). For this reason, during the cooling operation of the air conditioner (10), the expansion valve control unit (62) does not perform the startup expansion valve control operation or the dew condensation prevention control operation.

The startup expansion valve control operation will be described with reference to FIG. When the compressor control unit (61) activates the compressor (30) at time t ₀ in FIG boot, at the same time the expansion valve control section (62) of the expansion valve the opening of (43) from the fully closed normally closed Increase all at once. Then, the expansion valve control section (62), between times t ₁ to startup the compressor control operation of the compressor control section (61) is completed, the startup expansion valve control operation. The expansion valve control unit (62) during the start-up expansion valve control operation is provided each time the compressor control unit (61) during the start-up compressor control operation increases the rotational speed of the compressor (30). ) Is increased to a value corresponding to the rotational speed of the compressor (30) after being pulled up. That is, the expansion valve control unit (62) during the startup expansion valve control operation adjusts the opening degree of the expansion valve (43) in conjunction with the increase in the rotational speed of the compressor (30) by the compressor control unit (61). Increase it step by step.

The expansion valve control unit (62) performs a startup expansion valve control operation at the start of the heating operation. Here, the operation of starting the compressor (30) to start the heating operation is not only for starting the heating operation after turning on the power of the air conditioner (10), but also for the operating state of the air conditioner (10). It is also performed when switching from the cooling operation to the heating operation, or when switching the operation state of the air conditioner (10) from the defrosting operation to the heating operation. In addition, if the heating capacity of the air conditioner (10) is too large for the indoor heating load even if the rotation speed of the compressor (30) is set to the lower limit during the heating operation, the compressor (30) is temporarily stopped. (Thermo-off), and then the room temperature falls below the set temperature, the compressor (30) is started again (thermo-on). In any case where the compressor (30) is started to start such a heating operation, the expansion valve control unit (62) performs the startup expansion valve control operation.

The normal expansion valve control operation will be described. The expansion valve control unit (62) during the normal expansion valve control operation monitors the degree of superheat of the refrigerant at the outlet of the heat exchanger functioning as an evaporator. That is, the expansion valve control unit (62) monitors the degree of refrigerant superheat at the outlet of the indoor heat exchanger (46) when the cooling operation is being performed, and the outlet of the outdoor heat exchanger (42) when the heating operation is being performed. Monitor the degree of superheat of the refrigerant. The expansion valve control unit (62) adjusts the opening degree of the expansion valve (43) so that the superheat degree of the monitored refrigerant is maintained at a predetermined target superheat degree (for example, 5 ° C.). Specifically, the expansion valve controller (62) during the normal expansion valve control operation increases the opening of the expansion valve (43) if the superheat degree of the refrigerant at the outlet of the evaporator exceeds the target superheat degree, If the superheat degree of the refrigerant at the outlet of the evaporator is lower than the target superheat degree, the opening degree of the expansion valve (43) is reduced.

Describes the control action for preventing condensation. This dew condensation prevention control operation is performed in parallel with the normal expansion valve control operation. The expansion valve control unit (62) performs the normal expansion valve control operation and simultaneously performs the dew condensation prevention control operation shown in the flowchart of FIG. 4 at predetermined time intervals (for example, every 30 seconds).

In step ST11 of FIG. 4, the expansion valve control unit (62) reads the output of the dew condensation sensor (70). In the next step ST12, the expansion valve control unit (62) determines whether or not the dew condensation sensor (70) detects the occurrence of dew condensation. When the dew condensation sensor (70) does not detect the occurrence of dew condensation, the expansion valve control unit (62) returns to step ST11. On the other hand, when the dew condensation sensor (70) detects the occurrence of dew condensation, the expansion valve control unit (62) moves to step ST13. In step ST13, the expansion valve control section (62) stops the normal expansion valve control operation and forcibly increases the opening of the expansion valve (43) by a predetermined value.

After the opening of the expansion valve (43) is forcibly increased in step ST13, the expansion valve control unit (62) returns to step ST11 again and repeats the same operation. Therefore, while the dew condensation sensor (70) detects the occurrence of dew condensation, the opening degree of the expansion valve (43) increases every time the expansion valve control unit (62) performs the dew condensation prevention control operation. go. When the dew condensation sensor (70) does not detect the occurrence of dew condensation, the expansion valve control unit (62) resumes the normal expansion valve control operation, and the superheat degree of the refrigerant at the outlet of the evaporator is equal to the target superheat degree. The opening of the expansion valve (43) is adjusted so that

-Effect of Embodiment 1-
In this embodiment, the expansion valve control unit (62) of the controller (60) performs the startup expansion valve control operation when the compressor control unit (61) starts the compressor (30), and the expansion valve (43 ) Is set to an opening corresponding to the rotational speed of the compressor (30) at that time. For this reason, the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) is low while the opening of the expansion valve (43) remains small despite the increase in the rotational speed of the compressor (30). As a result, it is possible to avoid the trouble caused by the condensation on the power element (56) and its peripheral portion.

That is, as shown in FIG. 3 (A), the temperature of the cooling member (50) and the power element (56) temporarily decreases immediately after starting the compressor (30), but thereafter, As the rotational speed of the compressor (30) increases and the flow rate of the refrigerant passing through the expansion valve (43) increases, the opening of the expansion valve (43) is increased, so that the cooling member (50) And the temperature of the power element (56) is kept at a relatively high value.

In the controller (60) of the present embodiment, the start-up compressor control operation by the compressor control unit (61) and the start-up expansion valve control operation by the expansion valve control unit (62) are simultaneously performed in parallel. . That is, when the controller (60) starts the compressor (30) and starts the heating operation, the compressor control unit (61) gradually increases the rotational speed of the compressor (30) stepwise. Each time the rotational speed of the compressor (30) is increased, the expander control unit increases the opening of the expansion valve (43). For this reason, the expansion of the pressure difference before and behind the expansion valve (43) due to the increase in the rotational speed of the compressor (30) is suppressed, and the temperature of the refrigerant supplied to the cooling member (50) is excessively lowered. Is suppressed. Therefore, according to this embodiment, it is possible to avoid that the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) becomes too low in the refrigerant circuit (20) during the heating operation, and the cooling member ( 50), it is possible to reliably prevent the occurrence of dew condensation in the power element (56) cooled by the above and the surrounding area.

Here, when the compressor (30) that has been stopped is started, if the opening of the expansion valve (43) is too small, the pressure difference between the two sides of the expansion valve (43) will rapidly increase, causing expansion. There is a possibility that the temperature of the refrigerant sent from the valve (43) to the cooling member (50) may rapidly decrease. On the other hand, in the present embodiment, the expansion valve control unit (62) during the startup expansion valve control operation starts the expansion valve (43) simultaneously with the compressor control unit (61) starting the compressor (30). ) Is increased at a stretch to the opening at startup. For this reason, when the compressor (30) is activated and the refrigerant begins to pass through the expansion valve (43), the opening of the expansion valve (43) is already set to the opening at the time of activation, and the expansion valve (43) Since the expansion of the pressure difference between both sides of the refrigerant is reduced, the amount of decrease in the temperature of the refrigerant sent from the expansion valve (43) to the cooling member (50) in the refrigerant circuit (20) during the heating operation is reduced.

In the present embodiment, the expansion valve controller (62) of the controller (60) opens the expansion valve (43) when the condensation sensor (70) detects the occurrence of condensation on the surface of the cooling member (50). Forcibly increase the degree. When the opening degree of the expansion valve (43) increases in the refrigerant circuit (20) during the heating operation, the pressure difference between both sides of the expansion valve (43) is reduced, and the cooling member (50) is expanded from the expansion valve (43). The temperature of the refrigerant sent to the rises. Therefore, according to this embodiment, even after the start of the compressor (30) is completed and the normal operation state is reached, an excessive decrease in the surface temperature of the cooling member (50) can be suppressed, Problems caused by condensation on the surfaces of the power element (56) and the cooling member (50) can be prevented.

-Modification of Embodiment 1-
In the present embodiment, the dew condensation sensor (70) may be installed not on the cooling member (50) itself but on the periphery of the cooling member (50). In addition, the dew condensation sensor (70) may be installed in the power element (56) itself or in the periphery of the power element (56). Furthermore, the dew condensation sensor (70) may be installed in a portion of the wiring board (57) of the inverter device (55) located in the vicinity of the power element (56).

Further, the expansion valve control unit (62) of the controller (60) of the present embodiment continuously and gradually increases the opening of the expansion valve (43) while the dew condensation sensor (70) detects the occurrence of dew condensation. The increasing operation may be configured to be performed as a dew condensation prevention control operation.

<< Embodiment 2 of the Invention >>
A second embodiment of the present invention will be described. Here, about the air conditioner (10) of this embodiment, a different point from the said Embodiment 1 is demonstrated.

As shown in FIG. 5, in the air conditioner (10) of the present embodiment, a temperature sensor (73) is provided instead of the humidity sensor (74) of the first embodiment. The temperature sensor (73) is provided in the air conditioner (10) as a measuring means, and is a surface of the main body (51) of the cooling member (50) (more specifically, a surface in contact with the power element (56)). ). This temperature sensor (73) is a physical quantity that indicates the surface temperature of the main body (51) of the cooling member (50) as an index of the possibility of condensation on the surface of the power element (56) or the cooling member (50). Measure as The measurement value of the temperature sensor (73) is input to the controller (60).

Further, in the air conditioner (10) of the present embodiment, the outdoor temperature sensor (71) constitutes a measuring means. That is, in the controller (60) of the present embodiment, the temperature of the outdoor air measured by the outdoor air temperature sensor (71) is an indicator of the possibility of condensation on the surface of the power element (56) or the cooling member (50). Used as a physical quantity.

In the controller (60) of the present embodiment, the configuration of the expansion valve control unit (62) is different from that of the first embodiment. The expansion valve control unit (62) of the present embodiment is configured to execute an operation different from that of the first embodiment as a dew condensation prevention control operation. The startup expansion valve control operation and the normal expansion valve control operation performed by the expansion valve control unit (62) of the present embodiment are the same as the operations in the first embodiment.

The control operation for preventing dew condensation performed by the expansion valve control unit (62) of the present embodiment will be described with reference to the flowchart of FIG.

In step ST21 of FIG. 6, the expansion valve control unit (62) reads the measurement value Ta (that is, the actual measurement value of the outdoor air temperature) of the outdoor air temperature sensor (71). In the next step ST22, the expansion valve controller (62) reads the measured value Td of the temperature sensor (73) (that is, the actual measured value of the surface temperature of the main body (51) of the cooling member (50)). . In the next step ST23, the expansion valve control unit (62) compares the measured value Td of the temperature sensor (73) with the measured value Ta of the outdoor air temperature sensor (71). When the measured value Td of the temperature sensor (73) is equal to or greater than the measured value Ta of the outdoor air temperature sensor (71) (Td ≧ Ta), the expansion valve control unit (62) returns to step ST21. On the other hand, when the measured value Td of the temperature sensor (73) is lower than the measured value Ta of the outdoor air temperature sensor (71) (Td <Ta), the expansion valve control unit (62) moves to step ST24. In step ST24, the expansion valve control unit (62) stops the normal expansion valve control operation and forcibly increases the opening of the expansion valve (43) by a predetermined value.

After the opening of the expansion valve (43) is forcibly increased in step ST24, the expansion valve control unit (62) returns to step ST21 again and repeats the same operation. For this reason, while the measured value Td of the temperature sensor (73) is lower than the measured value Ta of the outdoor air temperature sensor (71), the expansion valve control unit (62) performs the dew condensation prevention control operation each time. The opening of (43) increases. When the measured value Td of the temperature sensor (73) becomes equal to or greater than the measured value Ta of the outdoor air temperature sensor (71), the expansion valve control unit (62) resumes the normal expansion valve control operation, and at the outlet of the evaporator. The opening degree of the expansion valve (43) is adjusted so that the superheat degree of the refrigerant becomes the target superheat degree.

Here, whether or not there is a high possibility that condensation occurs on the surfaces of the power element (56) and the cooling member (50) is determined by the measured value Td of the temperature sensor (73) and the measured value Ta of the outdoor air temperature sensor (71). The reason why the determination can be made using is described. In the air conditioner (10) of the present embodiment, the inverter device (55) and the cooling member (50) are accommodated in an outdoor unit (11) installed outdoors. That is, the state of the atmosphere around the inverter device (55) and the cooling member (50) is substantially equal to the state of outdoor air. On the other hand, since it is practically impossible for the relative humidity of the outdoor air to be 100%, the dew point temperature of the outdoor air is lower than the outdoor air temperature (that is, the dry bulb temperature of the outdoor air). For this reason, when the measured value Td of the temperature sensor (73) is lower than the measured value Ta of the outdoor air temperature sensor (71), the surface temperature of the cooling member (50) approaches the dew point temperature of the outdoor air, and the power It can be presumed that the possibility of dew condensation on the surfaces of the element (56) and the cooling member (50) is increased.

Therefore, when the measured value Td of the temperature sensor (73) is lower than the measured value Ta of the outdoor air temperature sensor (71) during the heating operation, the expansion valve control unit (62) of the present embodiment has a cooling member (50 ) Of the expansion valve (43) is forcibly increased in order to increase the temperature of the refrigerant flowing into the refrigerant pipe (52). Therefore, according to the present embodiment, as in the first embodiment, the surface temperature of the cooling member (50) is excessive even after the start-up of the compressor (30) is completed and the normal operation state is achieved. Can be prevented, and troubles due to condensation on the surfaces of the power element (56) and the cooling member (50) can be prevented.

In this embodiment, the temperature sensor (73) may be installed not on the cooling member (50) itself but on the periphery of the cooling member (50). Further, the temperature sensor (73) may be installed in the power element (56) itself or in the periphery of the power element (56). Furthermore, the temperature sensor (73) may be installed in a portion of the wiring board (57) of the inverter device (55) that is positioned in the vicinity of the power element (56).

As described above, the air conditioner (10) of the present embodiment measures the power element (56), the cooling member (50), or the temperature sensor (73) installed in the vicinity of the power element (56). The expansion valve control unit (62) of the controller (60) uses the measurement value of the temperature sensor (73) to cause condensation on the surface of the power element (56) or the cooling member (50). It is configured to determine whether or not the possibility is high. Furthermore, in this embodiment, the inverter device (55) and the cooling member (50) are installed outdoors, and both the outdoor air temperature sensor (71) and the temperature sensor (73) that measure the temperature of the outdoor air are measured. As a means, it is provided in the air conditioner (10). In addition, the expansion valve control unit (62) of the controller (60) of the present embodiment performs power when the measured value Td of the temperature sensor (73) is lower than the measured value Ta of the outdoor air temperature sensor (71). It is configured to determine that there is a high possibility of condensation on the surface of the element (56) or the cooling member (50).

<< Embodiment 3 of the Invention >>
Embodiment 3 of the present invention will be described. The air conditioner (10) of the present embodiment is obtained by changing the configuration of the expansion valve control unit (62) of the controller (60) in the second embodiment. Here, about the air conditioner (10) of this embodiment, a different point from the said Embodiment 2 is demonstrated.

The expansion valve control unit (62) of the present embodiment is configured to perform an operation different from that of the second embodiment as a dew condensation prevention control operation. Here, the dew condensation prevention control operation performed by the expansion valve control unit (62) of the present embodiment will be described while referring to the flowchart of FIG. 7 and different from the second embodiment.

In step ST31 of FIG. 7, the expansion valve control unit (62) reads the measured value Ta (that is, the actual measured value of the outdoor air temperature) of the outdoor air temperature sensor (71). In the next step ST32, the expansion valve control section (62) is a measurement value Ta of the outdoor air temperature sensor read temperature (71), the humid air, which is a reference humidity H ₁ relative humidity is stored in advance The dew point temperature Tw is calculated. In the expansion valve control section (62), reference humidity H ₁ is set to 60%. However, the value of the reference humidity H ₁ is merely an example.

In the next step ST33, the expansion valve control unit (62) reads the measurement value Td of the temperature sensor (73) (that is, the actual measurement value of the surface temperature of the main body (51) of the cooling member (50)). In subsequent step ST34, the expansion valve controller (62) compares the measured value Td of the temperature sensor (73) with the calculated dew point temperature Tw. When the measured value Td of the temperature sensor (73) is equal to or greater than the calculated dew point temperature value Tw (Td ≧ Tw), the expansion valve control unit (62) returns to step ST31. On the other hand, when the measured value Td of the temperature sensor (73) is below the calculated dew point temperature value Tw (Td <Tw), the expansion valve control unit (62) moves to step ST35. In step ST35, the expansion valve control unit (62) stops the normal expansion valve control operation, and forcibly increases the opening of the expansion valve (43) by a predetermined value.

After the opening of the expansion valve (43) is forcibly increased in step ST35, the expansion valve control unit (62) returns to step ST31 again and repeats the same operation. For this reason, while the measured value Td of the temperature sensor (73) is lower than the calculated dew point temperature value Tw, the expansion valve control unit (62) performs the dew condensation prevention control operation each time the dew point control operation is performed. The opening increases. When the measured value Td of the temperature sensor (73) becomes equal to or greater than the calculated dew point temperature value Tw, the expansion valve control unit (62) resumes the normal expansion valve control operation, and the degree of superheat of the refrigerant at the outlet of the evaporator Adjust the opening of the expansion valve (43) so that becomes the target superheat.

Here, the relative humidity of the outdoor air varies depending on the season, but it is possible to assume an approximate value in advance. Therefore, by setting the value to be assumed expansion valve control unit the reference humidity H ₁ in (62) as the relative humidity of the outdoor air, without actually measuring the relative humidity of the outdoor air, the dew point temperature of the outdoor air It is possible to calculate an approximate value of. On the other hand, condensation occurs on the surface of the cooling member (50) when the surface temperature of the cooling member (50) is lower than the dew point temperature of the surrounding air. For this reason, in a state where the measured value Td of the temperature sensor (73) is lower than the calculated dew point temperature value Tw, there is a high possibility that condensation occurs on the surfaces of the power element (56) and the cooling member (50). Can be guessed.

Therefore, the expansion valve control unit (62) of the present embodiment, when the measured value Td of the temperature sensor (73) is lower than the calculated dew point temperature Tw during the heating operation, the refrigerant pipe of the cooling member (50). In order to increase the temperature of the refrigerant flowing into (52), the opening degree of the expansion valve (43) is forcibly increased. Therefore, according to the present embodiment, as in the second embodiment, the surface temperature of the cooling member (50) is excessive even after the start-up of the compressor (30) is completed and the normal operation state is achieved. Can be prevented, and troubles due to condensation on the surfaces of the power element (56) and the cooling member (50) can be prevented.

As described above, the air conditioner (10) of the present embodiment measures the power element (56), the cooling member (50), or the temperature sensor (73) installed in the vicinity of the power element (56). The expansion valve control unit (62) of the controller (60) uses the measurement value of the temperature sensor (73) to cause condensation on the surface of the power element (56) or the cooling member (50). It is configured to determine whether or not the possibility is high. Furthermore, in this embodiment, the inverter device (55) and the cooling member (50) are installed outdoors, and both the outdoor air temperature sensor (71) and the temperature sensor (73) that measure the temperature of the outdoor air are measured. As a means, it is provided in the air conditioner (10). Further, the expansion valve control section of the controller (60) of this embodiment (62), the temperature relative humidity a measurement value Ta of the outdoor air temperature sensor (71) is humid air which is the reference humidity H ₁ a predetermined When the dew point temperature Tw is calculated and the measured value Td of the temperature sensor (73) is below the calculated dew point temperature Tw, condensation may occur on the surface of the power element (56) or the cooling member (50). It is configured to be judged as high.

<< Embodiment 4 of the Invention >>
Embodiment 4 of the present invention will be described. Here, about the air conditioner (10) of this embodiment, a different point from the said Embodiment 1 is demonstrated.

In the air conditioner (10) of the present embodiment, the dew condensation sensor (70) is omitted, while the outdoor air temperature sensor (71) and the indoor air temperature sensor (72) constitute measuring means. That is, in the controller (60) of the present embodiment, the temperature of the outdoor air measured by the outdoor air temperature sensor (71) and the temperature of the indoor air measured by the indoor air temperature sensor (72) are the power element (56) or the cooling. Used as a physical quantity serving as an index of the possibility of condensation on the surface of the member for use (50).

Referring to the flowchart of FIG. 8, the control operation for preventing condensation performed by the expansion valve control unit (62) of the present embodiment will be described with reference to the flowchart of FIG.

In step ST41 of FIG. 8, the expansion valve control unit (62) reads the measurement value Ta (that is, the actual measurement value of the outdoor air temperature) of the outdoor air temperature sensor (71). In the next step ST42, the expansion valve control unit (62) reads the measured value Ti (that is, the actual measured value of the indoor air temperature) of the indoor air temperature sensor (72). In subsequent step ST43, the expansion valve control unit (62) compares the measured value Ta of the outdoor air temperature sensor (71) with the measured value Ti of the indoor air temperature sensor (72). When the measured value Ti of the indoor air temperature sensor (72) is equal to or greater than the measured value Ta of the outdoor air temperature sensor (71) (Ti ≧ Ta), the expansion valve control unit (62) returns to step ST41. On the other hand, when the measured value Ti of the indoor air temperature sensor (72) is lower than the measured value Ta of the outdoor air temperature sensor (71) (Ti <Ta), the expansion valve control unit (62) moves to step ST44. In step ST44, the expansion valve control unit (62) stops the normal expansion valve control operation and forcibly increases the opening of the expansion valve (43) by a predetermined value.

After the opening of the expansion valve (43) is forcibly increased in step ST44, the expansion valve controller (62) returns to step ST41 again and repeats the same operation. Therefore, as long as the measured value Ti of the indoor air temperature sensor (72) is lower than the measured value Ta of the outdoor air temperature sensor (71), the expansion valve control unit (62) is inflated every time the dew condensation prevention control operation is performed. The opening of the valve (43) increases. When the measured value Ti of the indoor air temperature sensor (72) becomes equal to or higher than the measured value Ta of the outdoor air temperature sensor (71), the expansion valve control unit (62) resumes the normal expansion valve control operation, and the outlet of the evaporator The degree of opening of the expansion valve (43) is adjusted so that the superheat degree of the refrigerant at the target temperature becomes the target superheat degree.

Here, the measured value Ti of the indoor air temperature sensor (72) and the measured value of the outdoor air temperature sensor (71) determine whether or not there is a high possibility of condensation on the surfaces of the power element (56) and the cooling member (50). The reason why the determination can be made using Ta will be described. In the refrigerant circuit (20) during the heating operation, the refrigerant that exchanges heat with room air in the indoor heat exchanger (46) flows into the cooling member (50) after passing through the expansion valve (43). For this reason, when the indoor air temperature is lower than the outdoor air temperature, the temperature of the refrigerant flowing into the refrigerant pipe (52) of the cooling member (50) becomes lower than the outdoor air temperature, and the cooling member (50 ) And the power element (56) are more likely to be lower than the temperature of the outdoor air. On the other hand, since it is practically impossible for the relative humidity of the outdoor air to be 100%, the dew point temperature of the outdoor air is lower than the outdoor air temperature (that is, the dry bulb temperature of the outdoor air). When the measured value Ti of the indoor air temperature sensor (72) is lower than the measured value Ta of the outdoor air temperature sensor (71), the periphery of the power element (56), the cooling member (50), or the power element (56) It is highly probable that the temperature of the part is close to the dew point temperature of the outdoor air, and the possibility that condensation occurs on the surface of the power element (56) or the cooling member (50) is high.

Therefore, when the measured value Ti of the indoor air temperature sensor (72) falls below the measured value Ta of the outdoor air temperature sensor (71) during the heating operation, the expansion valve control unit (62) of the present embodiment In order to increase the temperature of the refrigerant flowing into the refrigerant pipe (52) of 50), the opening degree of the expansion valve (43) is forcibly increased. Therefore, according to the present embodiment, as in the first embodiment, the surface temperature of the cooling member (50) is excessive even after the start-up of the compressor (30) is completed and the normal operation state is achieved. Can be prevented, and troubles due to condensation on the surfaces of the power element (56) and the cooling member (50) can be prevented.

As described above, in the air conditioner (10) of the present embodiment, the refrigerant circuit (20) has the outdoor heat exchanger (42) that exchanges heat between the outdoor air and the refrigerant, and the heat exchange between the indoor air and the refrigerant. The refrigerant circuit (20) is connected to the indoor heat exchanger (46), and the refrigerant circuit (20) evaporates in the outdoor heat exchanger (42) after the refrigerant radiated in the indoor heat exchanger (46) is decompressed by the expansion valve (43). The refrigerant circuit (20) is configured to be capable of performing a heating operation for performing a refrigeration cycle, and a cooling member (42) between the outdoor heat exchanger (42) functioning as an evaporator during the heating operation and the expansion valve (43) 50) is arranged. In the present embodiment, an outdoor air temperature sensor (71) that measures the temperature of outdoor air and an indoor air temperature sensor (72) that measures the temperature of indoor air are provided in the air conditioner (10) as measuring means. . Furthermore, the expansion valve control unit (62) of the controller (60) of the present embodiment is configured such that the measured value Ti of the indoor air temperature sensor (72) is the outdoor air temperature sensor (71) while the refrigerant circuit (20) is performing the heating operation. ) Is lower than the measured value Ta, it is determined that there is a high possibility of condensation on the surface of the power element (56) or the cooling member (50).

<< Embodiment 5 of the Invention >>
Embodiment 5 of the present invention will be described. Here, about the air conditioner (10) of this embodiment, a different point from the said Embodiment 1 is demonstrated.

As shown in FIG. 9, in the air conditioner (10) of the present embodiment, a humidity sensor (74) is provided instead of the dew condensation sensor (70) of the first embodiment. The humidity sensor (74) is provided in the air conditioner (10) as a measuring means, and is installed in the vicinity of the cooling member (50) and the power element (56). The humidity sensor (74) may cause condensation on the surface of the power element (56) or the cooling member (50) due to the relative humidity of the air existing around the power element (56) or the cooling member (50). It is measured as a physical quantity that is an index of sex. The measured value of the humidity sensor (74) is input to the controller (60).

In the controller (60) of the present embodiment, the configuration of the expansion valve control unit (62) is different from that of the first embodiment. The expansion valve control unit (62) of the present embodiment is configured to execute an operation different from that of the first embodiment as a dew condensation prevention control operation. The startup expansion valve control operation and the normal expansion valve control operation performed by the expansion valve control unit (62) of the present embodiment are the same as those in the first embodiment.

The control operation for preventing condensation performed by the expansion valve control unit (62) of the present embodiment will be described with reference to the flowchart of FIG.

In step ST51 of FIG. 10, the expansion valve controller (62) measures the measured value Hp of the humidity sensor (74) (that is, the relative humidity of the air present around the power element (56) and the cooling member (50)). Read the actual measured value). In the next step ST52, the expansion valve control section (62) compares the measured value Hp upper humidity H ₂ and a humidity sensor stored in advance (74). In the expansion valve control section (62), reference humidity H ₂ is set to 60%. However, the value of the reference humidity H ₂ is merely an example.

In step ST52, when the measured value Hp of the humidity sensor (74) is the upper limit humidity H ₂ or less (Hp ≦ H _2), the expansion valve control section (62) returns to step ST51. On the other hand, when the measured value Hp of the humidity sensor (74) exceeds the upper limit humidity H ₂ (Hp> H _2), the expansion valve control section (62) moves to step ST53. In step ST53, the expansion valve control unit (62) stops the normal expansion valve control operation and forcibly increases the opening of the expansion valve (43) by a predetermined value.

After forcibly increasing the opening of the expansion valve (43) in step ST53, the expansion valve control unit (62) returns to step ST51 again and repeats the same operation. Therefore, while the measured value Hp of the humidity sensor (74) exceeds the upper limit humidity H _2, every time the expansion valve control section (62) performs prevention control operation condensation, the opening of the expansion valve (43) Will increase. When the measured value Hp of the humidity sensor (74) is below the upper limit humidity H _2, the expansion valve control section (62), the expansion valve control operation resumes normal, the degree of superheat of the refrigerant at the outlet of the evaporator the target The opening of the expansion valve (43) is adjusted so that the degree of superheat is reached.

Here, if the relative humidity of the air around the power element (56) has a certain high value, the dew point temperature of the air also becomes relatively high, and the power element (56) or the cooling member (50) There is a high possibility that the surface temperature is below the dew point temperature of the surrounding air. When the surface temperature of the power element (56) or the cooling member (50) is lower than the dew point temperature of the surrounding air, condensation occurs on the surface of the power element (56) or the cooling member (50). Thus, presumably the measured value Hp is higher than the upper limit humidity of H ₂ humidity sensor (74), surface Condensation may occur in the power element (56) and the cooling member (50) is higher it can.

Therefore, the expansion valve control section of the present embodiment (62), when the measured value Hp of the humidity sensor (74) is higher than the upper limit the humidity H _2, the refrigerant pipes of the cooling member (50) (52 ) To increase the opening of the expansion valve (43). Therefore, according to the present embodiment, as in the first embodiment, the surface temperature of the cooling member (50) is excessive even after the start-up of the compressor (30) is completed and the normal operation state is achieved. Can be prevented, and troubles due to condensation on the surfaces of the power element (56) and the cooling member (50) can be prevented.

As described above, the air conditioner (10) of the present embodiment is provided with the humidity sensor (74) that measures the relative humidity of the air around the power element (56) as the measuring means. Further, the expansion valve control section of the controller (60) of this embodiment (62), when the measured value Hp of the humidity sensor (74) exceeds a predetermined upper limit humidity H _2, a power element (56) or cooling It is configured to determine that there is a high possibility that condensation will occur on the surface of the structural member (50).

In addition, the above embodiment is an essentially preferable example, and is not intended to limit the scope of the present invention, its application, or its use.

As described above, the present invention is useful for a refrigeration apparatus that cools the power element (56) of the power source that supplies power to the compressor (30) with the refrigerant.

10 Air conditioner (refrigeration equipment)
20 Refrigerant circuit 30 Compressor 33 Electric motor 42 Outdoor heat exchanger (evaporator)
43 Expansion valve 50 Cooling member 55 Inverter unit (power supply)
56 Power element 60 Controller (control means)
70 Condensation sensor 71 Outdoor air temperature sensor (measuring means)
72 Indoor air temperature sensor (measuring means)
73 Temperature sensor (measuring means)
74 Humidity sensor (measuring means)

Claims

A refrigerant circuit (20) in which a compressor (30) and an expansion valve (43) are connected to perform a refrigeration cycle;
A power source (55) having a power element (56) and supplying power to the electric motor (33) of the compressor (30);
Cooling that is disposed between the expansion valve (43) and the evaporator (42) in the refrigerant circuit (20) and cools the power element (56) of the power source (55) by the refrigerant of the refrigerant circuit (20). A refrigeration apparatus comprising a member for use (50),
When starting the compressor (30), an expansion valve control operation for starting is performed to set the opening of the expansion valve (43) to an opening determined based on the rotational speed of the compressor (30). A refrigeration apparatus comprising control means (60).
In claim 1,
When the compressor (30) is started, the control means (60) performs a start-up compressor control operation for gradually increasing the rotational speed of the compressor (30) to a predetermined target rotational speed. And performing an operation of increasing the opening of the expansion valve (43) as the expansion valve control operation every time the rotational speed of the compressor (30) is increased in the compressor control operation. .
In claim 1,
The control means (60) increases the opening of the expansion valve (43) at a stroke to a predetermined starting opening in conjunction with the start of the compressor (30) at the start of the expansion valve control operation. Refrigeration equipment characterized.
In claim 2,
The control means (60) increases the opening of the expansion valve (43) at a stroke to a predetermined starting opening in conjunction with the start of the compressor (30) at the start of the expansion valve control operation. Refrigeration equipment characterized.
In any one of Claims 1 thru | or 4,
A dew sensor (70) installed near the power element (56), the cooling member (50), or the power element (56) to detect the occurrence of dew;
The control means (60) performs an operation of forcibly increasing the opening of the expansion valve (43) when the dew condensation sensor (70) detects the occurrence of dew condensation after the expansion valve control operation is completed. Refrigeration equipment.
In any one of Claims 1 thru | or 4,
Measuring means (71 to 74) for measuring a physical quantity serving as an index of the possibility of condensation on the surface of the power element (56) or the cooling member (50);
After the end of the expansion valve control operation, the control means (60) causes condensation on the surface of the power element (56) or the cooling member (50) based on the measurement values of the measurement means (71 to 74). A refrigeration apparatus that performs an operation of forcibly increasing the opening degree of the expansion valve (43) when it is determined that the possibility of occurrence is high.