JP5611179B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner, and more particularly to an air conditioner that can prevent a refrigerant from sleeping in a compressor.

  In the conventional air conditioner, in order to prevent the refrigerant from sleeping in the compressor, after the air conditioning operation is stopped, a weak current is passed through the motor winding of the compressor. (See Patent Document 1).

JP-A-8-226714 (refer to claim 1)

  However, when the air conditioner passed a weak current through the motor winding of the compressor, a constant current also flowed through the power module that drives the motor of the compressor. For this reason, the air conditioner cannot continue to flow a current exceeding the heat-resistant temperature of the power module even if a weak current continues to flow through the motor winding.

  Therefore, the air conditioner cannot keep a weak current flowing in the motor winding of the compressor. Therefore, the air conditioner may not be able to prevent the refrigerant from sleeping in the compressor.

  The present invention has been made in order to solve the above-described problems, and is to provide an air conditioner that can prevent a refrigerant from sleeping.

The air conditioner of the present invention is an air conditioner including a compressor and an inverter device that drives an electric motor of the compressor, wherein the inverter device includes a power module that drives the compressor, and the power A controller for controlling the module, and a temperature detector for detecting the temperature of the power module , wherein the first liquid refrigerant retention range and the first liquid refrigerant retention are below the range where the electric motor is installed. the second liquid refrigerant reservoir range than the range of the lower is set, the power module, the switching element is formed by wide-gap semiconductor elements, among the outer Guo before Symbol compressor, the first liquid refrigerant reservoir range the corresponding position, attached via a heat transfer member, and the flow of current to the motor, wherein, in a state where the compressor is stopped by the switching element The electric current is supplied to the electric motor, the energization is performed to heat the electric motor, and the liquid level height of the liquid refrigerant of the compressor is set to the first liquid refrigerant retention range according to the temperature change rate of the power module. And the second liquid refrigerant retention range .

  INDUSTRIAL APPLICABILITY The present invention has an effect that a long-term use of an air conditioner can be enabled by preventing the refrigerant from sleeping in the compressor.

It is a piping system figure of refrigerant circuit 11 of air harmony device 1 in Embodiment 1 of the present invention. It is the schematic which shows the external appearance structure of the compressor 21 in Embodiment 1 of this invention. It is a figure which shows the structure of the inverter apparatus 31 in Embodiment 1 of this invention. It is sectional drawing which shows schematically the internal structure of the compressor 21 in Embodiment 1 of this invention. It is a figure which shows the execution time of the restraint electricity supply after power activation in Embodiment 1 of this invention. It is a figure which shows the execution timing of the restraint electricity supply after the operation stop in Embodiment 1 of this invention. It is a figure which shows the comparison with the execution time of restraint electricity supply in Embodiment 1 of this invention, and the execution time of restraint electricity supply at the time of the exhaust heat of a power module. It is a figure which shows the residence range of the liquid refrigerant in Embodiment 2 of this invention. It is a figure which shows the time change rate of the temperature by the difference in the liquid level height in Embodiment 2 of this invention. It is a figure which shows the time change rate of the temperature by the difference in the retention range of the liquid refrigerant in Embodiment 2 of this invention.

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

Embodiment 1 FIG.
FIG. 1 is a piping system diagram of a refrigerant circuit 11 of the air-conditioning apparatus 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the air conditioner 1 includes a refrigerant circuit 11 and supplies cold air, hot air, or the like into the room by cooling operation or heating operation.

  The refrigerant circuit 11 is filled with a refrigerant, and performs a vapor compression refrigeration cycle by circulating the refrigerant in the refrigerant pipe. The refrigerant to be filled is, for example, an ammonia refrigerant or a chlorofluorocarbon refrigerant, but is not limited thereto.

  The refrigerant circuit 11 is formed by connecting a compressor 21, an indoor heat exchanger 22, an expansion valve 23, and an outdoor heat exchanger 24.

  The compressor 21 is installed in an outdoor unit (not shown) and compresses the refrigerant vapor. The compressor 21 is, for example, a rotary type compressor, and is driven and controlled by an inverter device 31 described later.

  The indoor heat exchanger 22 is installed in an indoor unit (not shown) and exchanges heat between the refrigerant supplied from the compressor 21 and room air, or the refrigerant supplied from the expansion valve 23 and room air. Heat exchange. The indoor heat exchanger 22 is formed with an indoor fan 26 in pairs, and the indoor fan 26 is installed in an indoor unit (not shown). Moreover, as for the indoor heat exchanger 22, a fin and a heat exchanger are formed from aluminum, for example.

  The expansion valve 23 is a decompression unit that is installed in an outdoor unit (not shown) and decompresses the refrigerant, and is formed of, for example, an electronic expansion valve. The expansion valve 23 depressurizes the refrigerant supplied from the indoor heat exchanger 22 and supplies it to the outdoor heat exchanger 24, or depressurizes the refrigerant supplied from the outdoor heat exchanger 24 to the indoor heat exchanger 22. Supply.

  The outdoor heat exchanger 24 is installed in an outdoor unit (not shown), and exchanges heat between the refrigerant supplied from the expansion valve 23 and the outdoor air, or the refrigerant supplied from the compressor 21 and the outdoor air. Heat exchange. The outdoor heat exchanger 24 is formed with a pair of outdoor fans 27, and the outdoor fans 27 are installed in an outdoor unit (not shown). Moreover, as for the outdoor heat exchanger 24, a fin and a heat exchanger are formed from aluminum, for example.

  The four-way switching valve 25 is installed in an outdoor unit (not shown) and forms four ports from first to fourth, and the connection relationship in the refrigerant circuit according to the operating state such as cooling operation or heating operation. Is to switch. The four-way switching valve 25 is connected to a discharge pipe 91 (which will be described later in FIG. 2) whose first port 45 is a discharge side of the compressor 21. The four-way switching valve 25 has a second port 46 connected to the indoor heat exchanger 22. The four-way switching valve 25 is connected to a suction pipe 71 (which will be described later with reference to FIG. 2) whose third port 47 is on the suction side of the compressor 21. The four-way switching valve 25 has a fourth port 48 connected to the outdoor heat exchanger 24. As shown by the solid line in FIG. 1, the four-way switching valve 25 is in a state in which the third port 47 and the fourth port 48 are connected when the first port 45 and the second port 46 are connected. The four-way switching valve 25 has a state where the second port 46 and the third port 47 are connected when the first port 45 and the fourth port 48 are connected, as shown by the broken line in FIG. Become. During the heating operation, the first port 45 and the second port 46 are connected, and the third port 47 and the fourth port 48 are connected. In the cooling operation, the first port 45 and the fourth port 48 are connected, and the second port 46 and the third port 47 are connected.

  The indoor fan 26 sucks in indoor air, and sends out air into the room where heat is exchanged between the sucked indoor air and the refrigerant flowing in the indoor heat exchanger 22.

  The outdoor fan 27 discharges air obtained by heat exchange between the refrigerant flowing inside the outdoor heat exchanger 24 and outdoor air to the outside of an outdoor unit (not shown).

  Although details will be described later, the inverter device 31 is formed of an electrical component part 41, a power module 42, and a heat transfer part 43, and controls the drive of the compressor 21 to transfer the heat of the power module 42 to the heat transfer part. It is supplied to the compressor 21 through 43.

  The electrical component section 41 includes a converter circuit 111, an inverter circuit 112, and a control CPU 113 which will be described later. The electrical component part 41 is formed, for example, in an electrical component box (not shown) of the outdoor unit.

  However, as will be described later with reference to FIG. 3, the power module 42 is included in the inverter circuit 112 in terms of circuit configuration, but is not inside the electrical component part 41 in which the main elements of the inverter circuit 112 are mounted, It is provided outside the electrical component part 41.

  The power module 42 is formed of a wide band gap element and generates alternating current with a variable frequency. A wide band gap device is a semiconductor having a band gap larger than 2 [eV], such as a nitride semiconductor such as gallium nitride (GaN), silicon carbide (SiC), or diamond, and has high heat resistance. It is an element. For example, the band gap of gallium nitride (GaN) is 3.4 [eV], and the band gap of silicon carbide (SiC) is 3.2 [eV]. The breakdown electric field strength of gallium nitride (GaN) is 3.0 [MV / cm], and the breakdown electric field strength of silicon carbide (SiC) is 3.0 [MV / cm]. Further, silicon (Si) conventionally used as a material for circuit elements has a band gap of 1.1 [eV] and a dielectric breakdown electric field strength of 0.3 [MV / cm].

  The fact that the breakdown field strength is large and the band gap width is large means that the on-resistance can be lowered by thinning the element while maintaining the breakdown voltage. If the on-resistance can be lowered, power loss can be reduced. Since the power loss can be reduced, the calorific value is reduced. By reducing the amount of heat generated, the temperature is unlikely to rise even if the module is downsized and the heat capacity is reduced.

  The band gap here is an energy region where electrons cannot exist inside the substance. In addition, the dielectric breakdown electric field strength here is the maximum electric field strength that causes dielectric breakdown in a semiconductor or an insulator.

  That is, the wide band gap element has a band gap width about 3 times wider and a breakdown field strength about 10 times larger than a conventional silicon element. For this reason, the heat resistance and voltage resistance are superior to those of silicon. An excellent heat resistance means that it can operate at a high temperature. Therefore, the cooling structure can be reduced in size by using the wide band gap element.

Furthermore, gallium nitride (GaN) and silicon carbide (SiC) have a higher electric field saturation rate than silicon (Si). Specifically, in the case of gallium nitride (GaN), it is 2.7 [1 × 10 ⁷ cm / s], and in the case of silicon carbide (SiC), it is 2.0 [1 × 10 ⁷ cm / s]. In the case of silicon (Si), it is 1.0 [1 × 10 ⁷ cm / s]. A high electric field saturation speed means that high-frequency driving is possible. Peripheral parts can be reduced in size because high frequency driving is possible.

  Conventionally, the power module 42 uses an element formed of silicon. Therefore, since it is weak at high temperature, it was not excellent in heat resistance. Further, since the power loss is large due to the element formed of silicon, the amount of heat generation is large, and the module cannot be reduced in size. Moreover, since the power loss was large, noise was often emitted to the outside. Therefore, in the past, the power module 42 was provided inside the electrical component part 41 and had to be radiated by attaching a heat sink or the like. For this reason, when the power module 42 is formed of an element formed of silicon, the power module 42 is subjected to structural restrictions.

  On the other hand, in the present invention, the power module 42 mounts the switching element using the band gap element described above. Therefore, since it is resistant to high temperatures, it has excellent heat resistance, and since power loss is small, the amount of heat generated is small, and the module can be downsized. In addition, since power loss is small, it is difficult to generate noise to the outside. Therefore, compared with the conventional case, the power module 42 does not need to be provided in the electrical component part 41, and it is not necessary to dissipate heat by attaching a heat sink or the like. For this reason, when the power module 42 is formed of a band gap element, the power module 42 is not subjected to structural restrictions. Therefore, in the present invention, the power module 42 can be provided at a location physically separated from the electrical component part 41.

  The heat transfer unit 43 is a heat transfer member and efficiently transfers the heat of the power module 42 to the outer shell of the compressor 21. The heat transfer section 43 is formed in a shape that comes into contact with the outer surface of the compressor 21 on the surface. The heat transfer part 43 is made of a material having high thermal conductivity, and is made of, for example, aluminum or copper. The heat transfer section 43 is provided with a temperature detection thermistor 44 described later.

  Here, the outdoor unit is divided into a space between a machine room and a blower room (both not shown). The compressor 21, the inverter device 31, the expansion valve 23, and the four-way switching valve 25 are arranged inside a machine room (not shown) that is a space sealed with sheet metal in the outdoor unit. Moreover, the outdoor heat exchanger 24 and the outdoor fan 27 are arrange | positioned in the air blower room interior which is a different area | region from a machine room.

  In addition, each structure of the air conditioning apparatus 1 demonstrated above shows an example, and is not limited to these.

  Next, the external appearance of the compressor 21 will be described with reference to FIG. 2, and the inverter device 31 that drives and controls the compressor 21 will be described with reference to FIG. 3.

  FIG. 2 is a schematic diagram showing an external configuration of the compressor 21 according to Embodiment 1 of the present invention. As shown in FIG. 2, the compressor 21 has a sealed space formed therein by connecting the top plate portion 81, the body portion 82, and the bottom plate portion 83 by welding or the like. The top plate portion 81, the body portion 82, and the bottom plate portion 83 are made of a metal material such as iron, for example.

  The top plate portion 81 includes a discharge pipe 91, and the discharge pipe 91 is connected to the first port 45 shown in FIG. 1 via a refrigerant pipe. The discharge pipe 91 discharges the refrigerant compressed by the compressor 21 to the outside of the compressor 21. Further, the signal line 53 from the power module 42 is connected to the top panel 81. The compressor 21 receives and controls a command from the power module 42 via the signal line 53 to drive and control a brushless DC motor 102 described later. That is, the compressor 21 is electrically connected to the inverter device 31 via the signal line 53. Then, at the time of restraint energization for preventing the stagnation of the refrigerant, which will be described later, a weak current is passed to the brushless DC motor 102 via the signal line 53. The restraint energization command is transmitted from the electrical component part 41 to the power module 42 via the signal line 51. Further, a detection signal from the temperature detection thermistor 44 is supplied to the electrical component section 41 via the signal line 52.

  Here, the signal lines 51 and 52 are signal lines formed with a length of about 1 [m], for example. That is, when forming the power module 42, the electrical component part 41 and the power module 42 are electrically connected with a distance of about 1 [m] by using a wide gap semiconductor element such as SiC. Is possible.

  The trunk portion 82 is connected to the suction muffler 61 via the upper connecting pipe 72 and the lower connecting pipe 73. The suction muffler 61 includes a suction pipe 71, an upper connection pipe 72, and a lower connection pipe 73. The suction muffler 61 sucks the refrigerant supplied from the refrigerant circuit 11 shown in FIG. 1 through the refrigerant pipe and supplies the refrigerant to the compressor 21. To do. The suction pipe 71 is provided at the upper end of the suction muffler 61, and the upper connection pipe 72 and the lower connection pipe 73 are provided at the lower end of the suction muffler 61. Specifically, the suction pipe 71 sucks the refrigerant from the refrigerant circuit 11 via the refrigerant pipe, and then supplies the refrigerant to the upper compression chamber 124 (described later in FIG. 4) via the upper connection pipe 72 to be connected to the lower connection. The refrigerant is supplied to the lower compression chamber 125 (described later in FIG. 4) through the pipe 73.

  FIG. 3 is a diagram showing a configuration of the inverter device 31 according to the first embodiment of the present invention. As shown in FIG. 3, the inverter device 31 includes a converter circuit 111, an inverter circuit 112, a control CPU 113, and a temperature detection thermistor 44.

  The converter circuit 111 is connected to the AC power source 101, and rectifies the AC supplied from the AC power source 101 and converts it into DC. Specifically, the converter circuit 111 is formed of, for example, an AC reactor, a diode bridge, a shunt resistor, a power switch element, an electrolytic capacitor, and the like (all not shown), and rectifies and rectifies the AC. And the smoothed direct current is supplied to the inverter circuit 112. Note that the AC power source 101 here is a commercial power source.

  The inverter circuit 112 is connected to the converter circuit 111, the control CPU 113, and the brushless DC motor 102. The inverter circuit 112 converts the smoothed direct current supplied from the converter circuit 111 into a PWM signal in accordance with a command from the control CPU 113 and converts the smoothed direct current motor 102 inside the compressor 21 (described later in FIG. 4). The brushless DC motor 102 is driven and controlled.

  Specifically, the inverter circuit 112 is formed of a snubber capacitor (not shown), a shunt resistor (not shown), the power module 42, and the like. The power module 42 is included in the inverter circuit 112 as a circuit configuration, but is separated from other elements as shown in FIGS. 1 and 2 and FIGS. 4 and 8 to be described later as a physical configuration. Provided in different positions.

  The power module 42 generates a PWM signal by switching the DC output supplied from the converter circuit 111. The power module 42 supplies the generated PWM signal to the brushless DC motor 102. The brushless DC motor 102 controls the rotation by generating a rotating magnetic field based on the supplied PWM signal.

  The temperature detection thermistor 44 detects the temperature of the power module 42 via the heat transfer section 43 at a predetermined cycle, and supplies the detection result to the control CPU 113.

  The control CPU 113 controls a driver (not shown) of the power module 42 based on an external control signal, a detection result of the temperature detection thermistor 44, and a PWM signal. Thereby, the power module 42 switches the band gap element which is a switching element mounted in the inside of the power module 42 with the switching frequency suitable for the condition based on various conditions. As a result, the brushless DC motor 102 rotates at a rotational speed according to the conditions, and generates output torque. Thereby, the compressor 21 will be driven according to conditions.

The “temperature detection thermistor 44” corresponds to the “temperature detection unit” in the present invention.
The “control CPU 113” corresponds to the “control unit” in the present invention.

  Next, the exhaust heat structure of the power module which is the principal part of this invention is demonstrated using FIG.

  FIG. 4 is a cross-sectional view schematically showing the internal configuration of the compressor 21 according to Embodiment 1 of the present invention. As shown in FIG. 4, the compressor 21 includes a brushless DC motor 102 and a compression mechanism 123. The description of the same reference numerals as those in FIG. 2 will be omitted.

  The brushless DC motor 102 is formed of a stator 131 and a rotor 132, and generates a rotating magnetic field in the stator 131 by a PWM signal supplied from the power module 42, thereby rotating the rotor 132, thereby being fixed to the rotor 132. The crankshaft 122 is rotated.

  The stator 131 is formed of a winding, an iron core, a substrate, and the like (all not shown). A current is passed from the substrate to the winding based on the supplied PWM signal, and the stator 131 is wound around the iron core a predetermined number of times. A winding generates a rotating magnetic field with respect to the rotor 132 by generating an induction magnetic field.

  The rotor 132 is formed of a permanent magnet and is rotated by a rotating magnetic field generated by the stator 131. A crankshaft 122 is fixed to the rotor 132, and the crankshaft 122 includes a crankshaft upper eccentric portion 122a and a crankshaft lower eccentric portion 122b that rotate eccentrically in conjunction with its rotation.

  The “brushless DC motor 102” corresponds to the “electric motor” in the present invention.

  The compression mechanism 123 is formed from an upper compression chamber 124 and a lower compression chamber 125. The upper compressor chamber 124 is formed from a frame 141, an upper cylinder 142, and a partition plate 143. The lower compression chamber 125 is formed by a partition plate 143, a lower cylinder 144, and a cylinder head 145. The upper cylinder 142 is connected to the upper connecting pipe 72 and is driven by the eccentric rotation of the crankshaft upper eccentric portion 122a to compress the refrigerant. The lower cylinder 144 is connected to the lower connecting pipe 73 and is driven by the eccentric rotation of the crankshaft lower eccentric portion 122b to compress the refrigerant.

  Specifically, the refrigerant sucked from the refrigerant circuit 11 is sucked into the suction muffler 61 through the suction pipe 71. When the rotor 132 rotates, the crankshaft 122 rotates. When the crankshaft 122 rotates, an upper rolling piston (not shown) is eccentrically rotated by the crankshaft upper eccentric portion 122a, and at the same time, a lower rolling piston (not shown) is eccentrically rotated by the crankshaft lower eccentric portion 122b. At this time, the refrigerant is supplied to the upper cylinder 142 via the upper connecting pipe 72. At the same time, the refrigerant is supplied to the lower cylinder 144 via the lower connecting pipe 73. Then, the refrigerant is compressed by the upper rolling piston and the upper vane (not shown), the refrigerant is compressed by the lower rolling piston and the lower vane (not shown), and the compressed refrigerant is discharged by the discharge pipe 91. It is discharged outside.

  The first liquid level height 151 is set to the height of the lower end portion of the brushless DC motor 102 when the direction from the bottom plate portion 83 to the discharge pipe 91 is set to the upper side. A first threshold value is indicated.

  The second liquid level height 152 is set to a height in the vicinity of the upper end portion of the upper cylinder 142 when the direction from the bottom plate portion 83 to the discharge pipe 91 is set upward. A second threshold value is indicated.

  The installation range 161 is a range between the first liquid level height 151 and the second liquid level height 152, and the power module 42 is placed in this range of the compressor 21 via the heat transfer unit 43. It will be installed in the outer shell.

  By providing the power module 42 in the installation range 161, the heat generated in the power module 42 is supplied to the outline of the compressor 21 via the heat transfer section 43, and is supplied from the outline of the compressor 21 to the inside of the compressor. As described above, by limiting the installation range of the power module 42 to the installation range 161, heat is accurately supplied to the inside of the compressor 21. That is, in the range above the first liquid level height 151, heat can be supplied by the windings that are constituent elements of the stator 131 as usual. On the other hand, the liquid refrigerant staying in the internal space of the compressor 21 in the installation range 161 cannot be sufficiently supplied with heat by the windings that are constituent elements of the stator 131. Therefore, heat is supplied to the range from the power module 42.

  In addition, the structure of the compressor 21 demonstrated above shows an example of a twin rotary type compressor, and is not limited to this. For example, it goes without saying that a single rotary compressor may be used.

  Next, after explaining a general phenomenon about the restraint energization for preventing the stagnation of the refrigerant, it will be described with reference to FIGS.

  First, general phenomena will be described.

  A case is assumed where the operation of the compressor 21 is stopped in a low temperature state. At this time, when the outside air temperature rises, heat is transferred from the outside air temperature to the outdoor unit. When heat is transmitted to the outdoor unit, the heat is also transmitted to the outdoor heat exchanger 24, the compressor 21, and the like inside the outdoor unit.

  However, the outdoor heat exchanger 24 is made of aluminum, and the compressor 21 is made of iron. Therefore, the outdoor heat exchanger 24 has a higher thermal conductivity than the compressor 21. Therefore, the temperature of the outdoor heat exchanger 24 rises faster as the outside air temperature rises. As a result, a temperature difference occurs between the outdoor heat exchanger 24 and the compressor 21. The occurrence of a temperature difference means that a pressure difference is generated between the outdoor heat exchanger 24 and the compressor 21. Therefore, when the outside air temperature rises when the operation of the compressor 21 is stopped in a low temperature state, the outdoor heat exchanger 24 becomes the high pressure side, and the compressor 21 becomes the low pressure side. As a result, a refrigerant collects in the compressor 21 and a phenomenon that the liquid refrigerant accumulates inside the compressor 21 (hereinafter referred to as a refrigerant stagnation phenomenon) occurs.

  When the refrigerant stagnation phenomenon occurs, the starting load increases when the compressor 21 is shifted from the stopped state to the operating state. Therefore, the compressor 21 may be damaged. In addition, since the starting load is large, a system abnormality may occur due to a large starting current flowing. In such a state, the compressor 21 may not be restarted.

  Therefore, in general, as a measure for preventing the refrigerant stagnation phenomenon, when the outdoor unit is turned on, the winding of the brushless DC motor 102 is wound by a switching element such as a power element that forms the power module 42 for a certain period of time. On the other hand, the high frequency alternating voltage which the compressor 21 does not drive is applied. The flow of current through the winding in this way is referred to as restraint energization. Thus, the winding is heated, and the liquid refrigerant accumulated in the compressor 21 is discharged from the compressor 21 by the heat generated from the winding. The restraint energization after turning on the power to the outdoor unit will be described with reference to FIG.

  FIG. 5 is a diagram showing the execution time of restraint energization after the power is turned on in Embodiment 1 of the present invention. As shown in FIG. 5, after the power is turned on, restraint energization is executed for a predetermined time indicated by an execution time 171. The execution time 171 is, for example, 4 hours.

  In addition, although the example which performs restraint electricity supply for 4 hours was demonstrated here, it is not limited to this. In the outdoor unit, there is almost no temperature difference between the outdoor heat exchanger 24 and the compressor 21 so that the refrigerant stagnation phenomenon does not occur.

  Next, another example of measures for preventing the refrigerant stagnation phenomenon will be described with reference to FIG.

  FIG. 6 is a diagram showing the execution timing of restraint energization after operation stop in Embodiment 1 of the present invention. In FIG. 6, it is assumed that restraint energization is performed after the operation of the compressor 21 is stopped. As shown in FIG. 6, after a predetermined time has elapsed after the operation of the compressor 21 is stopped, restraint energization is executed at predetermined intervals indicated by execution timings 191, 192, 193. When the execution timings 191, 192, 193,... Are collectively referred to as the execution timing 190.

  Here, the first predetermined time after the operation stop of the compressor 21 is, for example, 30 minutes. The execution timing 191 is, for example, 30 minutes, the execution timing 192 is, for example, 30 minutes, and the execution timing 193 is, for example, 30 minutes. As shown in FIG. 6, after the operation of the compressor 21 is stopped, restraint energization that prevents the refrigerant stagnation phenomenon is always performed at a predetermined interval until the compressor 21 resumes operation next time. .

  As shown in FIGS. 5 and 6, the restraint energization is performed over a long period of time. Therefore, the switching elements constituting the power module 42 may be destroyed if the heat resistance is low. In order to continue the restraint energization, it is necessary to perform the restraint energization as long as the heat resistance of the switching element can be maintained. there were. For this reason, conventionally, there has been a case where sufficient energization cannot be performed. Therefore, the power module 42 is configured using the wide band gap element described above. Thereby, an element with high heat resistance is used for the power module 42. Therefore, as shown in FIG. 5 and FIG. Even if a wide bandgap element is used, there is a limit to heat resistance. Therefore, as described above, the power module 42 is provided in the installation range 161. Thereby, the exhaust heat of the power module 42 can be performed efficiently.

  Further, as shown in FIG. 4, by providing the power module 42 in the installation range 161, the liquid refrigerant can be heated by the power module 42 in addition to heating the liquid refrigerant by restraint energization. For example, in the past, it is assumed that 25 [W] was used for restraint energization. At this time, it is assumed that the module loss of the power module 42 is 25 [W]. In this case, conventionally, 25 [W] is always discarded as a module loss, and power is wasted accordingly. In the present embodiment, the discarded module loss is used to prevent the refrigerant stagnation phenomenon as shown in FIG.

  FIG. 7 is a diagram showing a comparison between the execution time of restraint energization in Embodiment 1 of the present invention and the execution time of restraint energization during exhaust heat of the power module. As shown in FIG. 7, in the case of only the restricted energization, the restricted energization is executed for the time indicated by the execution time 201. On the other hand, as shown in FIG. 7, when energization is performed in a state where the exhaust heat of the power module 42 is used, the energization is performed for the time indicated by the execution time 202. That is, the energization time can be shortened by the difference 211.

  Next, on the premise of the above configuration, the operation of the air conditioner 1 will be described.

  The air conditioner 1 can perform any one of a cooling operation, a heating operation, and restraint energization. The inverter device 31 performs any one of the cooling operation, the heating operation, and the restraint operation by controlling the driving of the compressor 21.

  In the case of the cooling operation, the four-way switching valve 25 is in a state indicated by a broken line in FIG. Further, the expansion valve 23 and the outdoor fan 27 perform the predetermined operation described above. Further, as described above, the compressor 21 is driven at a predetermined frequency and output torque. As a result, the refrigerant sucked from the suction pipe 71 is compressed by the compressor 21 to become a high-pressure refrigerant and is discharged from the discharge pipe 91.

  In the case of heating operation, the four-way switching valve 25 is in the state indicated by the solid line in FIG. Further, the expansion valve 23 and the outdoor fan 27 perform the predetermined operation described above. Further, as described above, the compressor 21 is driven at a predetermined frequency and output torque. As a result, the refrigerant sucked from the suction pipe 71 is compressed by the compressor 21 to become a high-pressure refrigerant and is discharged from the discharge pipe 91.

  In the case of restraint energization, the control CPU detects that the outside air temperature has risen by the temperature detection thermistor 44. When the control CPU detects that the outside air temperature has risen, the control CPU starts restraint energization to pass a current through the winding provided in the stator 131.

  Specifically, a high-frequency phase loss current is supplied to only two phases of the three phases of the winding. For example, the power module 42 causes a high-frequency phase loss current to flow at an execution timing 190 illustrated in FIG. That is, in this case, the power module 42 intermittently passes a high-frequency phase loss current through the winding. As a result, heat is generated in the winding due to copper loss. At the same time, the power module 42 continues to pass current through the windings, causing module loss and increasing the module temperature, which is the temperature of the main body. This heat is supplied to the installation range 161 shown in FIG. As a result, the power module 42 itself is also cooled. As a result, heat is uniformly transmitted to the liquid refrigerant throughout the compressor 21.

  Further, the winding may be heated by a frequency component outside the operating frequency range of the brushless DC motor 102 of the compressor 21 instead of the high-frequency phase loss current. In this case, the high frequency voltage is applied to the brushless DC motor 102 by operating at a frequency higher than the operating frequency (˜1 kHz) during the compression operation. In this way, there is no rotational torque or vibration, and high-frequency voltage application increases the winding impedance and reduces the current flowing in the winding and reduces copper loss. The iron loss due to this occurs, and the winding can be effectively heated. At the same time, the power module 42 supplies heat to the compressor 21 as described above. Therefore, even in this case, heat is uniformly transmitted to the liquid refrigerant throughout the compressor 21.

  By doing so, the power module 42 can discharge heat to the liquid refrigerant staying inside the compressor 21. Thereby, the temperature rise of the power module 42 can be suppressed and restraint energization can be performed over a long period of time.

  Further, since heating is performed by the power module 42 in addition to heating by the winding, the energization time to the winding can be shortened. Thereby, power consumption can be suppressed.

  In addition to heating by the winding, heating is performed by the power module 42, so that the energization amount to the winding can be reduced. Thereby, power consumption can be suppressed.

  In addition, the process of performing the energizing energies corresponds to the process of consuming the standby power, but the power consumption of the energizing energization can be suppressed, so that the standby power can be reduced. . Therefore, it can be adapted to European EuP Directive (Directive on Eco-Design of Energy-using Products) and Australian MEPS (Minimum Energy Performance Standards). Furthermore, even when an item for reducing standby power is added to an APF (Annual Performance Factor), it is possible to reduce the power consumption of restraint energization, thereby adapting to such an APF. it can.

  As described above, in the first embodiment, the air conditioner 1 includes the compressor 21 and the inverter device 31 that drives the brushless DC motor 102 of the compressor 21, and the inverter device 31 is compressed. A power module 42 for driving the machine 21 is provided, and the power module 42 is attached to the outer shell of the compressor 21 in a range below the range where the brushless DC motor 102 is installed, and allows a current to flow through the brushless DC motor 102. As a result, the refrigerant can be prevented from sleeping in the compressor 21.

  Further, in the first embodiment, the power module 42 forms a switching element with a wide gap semiconductor element, is attached to the outer wall via the heat transfer section 43, and when the compressor 21 is stopped, the brushless DC motor 102 When the energization is performed, a current is passed to the brushless DC motor 102 by the switching element, and the heat generated by the switching element is sent to the compressor 21 via the heat transfer section 43. By supplying, heat can be discharged to the liquid refrigerant staying inside the compressor 21 by the power module 42. Thereby, the temperature rise of the power module 42 can be suppressed and restraint energization can be performed over a long period of time.

Embodiment 2. FIG.
The difference from Embodiment 1 is that the power module 42 has added processing for detecting the height of the liquid refrigerant inside the compressor 21.

  In the second embodiment, items that are not particularly described are the same as those in the first embodiment, and the same functions and configurations are described using the same reference numerals.

  FIG. 8 is a diagram showing a liquid refrigerant retention range in Embodiment 2 of the present invention. As shown in FIG. 8, a first liquid refrigerant retention range 221 is set between the first liquid level height 151 and the second liquid level height 152, and the second liquid level height 152 is set. And the third liquid level height 153, the second liquid refrigerant retention range 222 is set.

  The first liquid refrigerant retention range 221 means that the liquid refrigerant stays in that range. That is, if the liquid refrigerant stays within the range, the heat from the power module 42 is transferred to the liquid refrigerant staying in the compressor 21, so that the module temperature detected by the temperature detection thermistor 44 is reached. The rise in module temperature per hour calculated based on this is moderate.

  The second liquid refrigerant staying range 222 means that the liquid refrigerant may stay in that range. That is, assuming that the liquid refrigerant stays within the range, the liquid refrigerant does not exist in the first liquid refrigerant staying range 221. As a result, heat from the power module 42 is not transferred to the liquid refrigerant. For this reason, the increase in module temperature per time calculated based on the module temperature detected by the temperature detection thermistor 44 becomes large.

  In other words, the liquid level can be estimated from the degree of inclination of the module temperature per time calculated based on the module temperature detected by the temperature detection thermistor 44 (hereinafter referred to as the module temperature change rate). . Specifically, there is a correlation between the module temperature change rate and the liquid level. The correlation will be described with reference to FIGS.

  FIG. 9 is a diagram showing a time change rate of temperature due to a difference in liquid level in Embodiment 2 of the present invention. As shown in FIG. 9, the first value 231 and the second value 232 indicate the time at a certain time point. In a range between the first value 231 and the second value 232, the module temperature change rate is moderate. When the second value 232 is exceeded, the module temperature change rate changes rapidly. That is, after the time of the second value 232, it means that heat is not transferred to the liquid refrigerant. That is, in this case, the height of the liquid refrigerant is lower than the second liquid level height 152 shown in FIG.

  Specifically, as shown in FIG. 9, in the first region 241 showing the rate of change in temperature with time, ΔT, which is the module temperature rise, is small with respect to time Δt. On the other hand, in the second region 242 showing the time change rate of the temperature, ΔT, which is the module temperature rise, is large with respect to the time Δt. Therefore, the liquid level of the liquid refrigerant can be estimated from the module temperature change rate.

  FIG. 10 is a diagram showing the time change rate of temperature due to the difference in the retention range of the liquid refrigerant in the second embodiment of the present invention. As shown in FIG. 10, the module temperature change rate differs between the first liquid refrigerant retention range 221 and the second liquid refrigerant retention range 222. Therefore, the liquid level of the liquid refrigerant can be estimated from the module temperature change rate.

  Therefore, depending on the module temperature change rate, the liquid level height is in the range of the first liquid level height 151 to the second liquid level height 152 or the second liquid level height 152 to the third level. It can be estimated whether the liquid level is in the range of 153. Thereby, the timing which stops a heating will be understood. That is, if it is the retention range 222 of the 2nd liquid refrigerant, it will not be necessary to heat any more. Therefore, heating can be performed as necessary when necessary. Therefore, power consumption can be reduced.

  As described above, the second embodiment includes the control CPU 113 that controls the power module 42 and the temperature detection thermistor 44 that detects the temperature of the power module 42, and the control CPU 113 includes the temperature detection thermistor. Based on the temperature detected at 44, the temperature change rate per hour is calculated, and when the temperature change rate per hour changes during execution of restraint energization, the power module 42 stops the current flowing to the brushless DC motor 102. Thus, the liquid level can be estimated. Therefore, heating can be performed as necessary when necessary. Therefore, power consumption can be reduced.

  DESCRIPTION OF SYMBOLS 1 Air conditioning apparatus, 11 Refrigerant circuit, 21 Compressor, 22 Indoor heat exchanger, 23 Expansion valve, 24 Outdoor heat exchanger, 25 Four-way switching valve, 26 Indoor fan, 27 Outdoor fan, 31 Inverter apparatus, 41 Electrical component Part, 42 power module, 43 heat transfer part, 44 temperature detection thermistor, 45 first port, 46 second port, 47 third port, 48 fourth port, 51, 52, 53 signal line, 61 suction muffler, 71 Suction pipe, 72 Upper connection pipe, 73 Lower connection pipe, 81 Top plate part, 82 Body part, 83 Bottom plate part, 91 Discharge pipe, 101 AC power supply, 102 Brushless DC motor, 111 Converter circuit, 112 Inverter circuit, 113 For control CPU, 122 crankshaft, 122a crankshaft upper eccentric part, 122b crankshaft lower Eccentric part, 123 Compression mechanism part, 124 Upper compression chamber, 125 Lower compression chamber, 131 Stator, 132 Rotor, 141 Frame, 142 Upper cylinder, 143 Partition plate, 144 Lower cylinder, 145 Cylinder head, 151 First liquid level Height, 152 Second liquid level, 153 Third liquid level, 161 Installation range, 171, 201, 202 Execution time, 190, 191, 192, 193 Execution timing, 211 Difference, 221 First Residence range of liquid refrigerant, 222 Residence range of second liquid refrigerant, 231 1st value, 232 2nd value, 241 First region showing time change rate of temperature 242 First showing temperature change rate of temperature 2 areas.

Claims (4)

An air conditioner comprising a compressor and an inverter device for driving an electric motor of the compressor,
The inverter device is
A power module for driving the compressor ;
A control unit for controlling the power module;
A temperature detector for detecting the temperature of the power module;
With
Below the range in which the electric motor is installed, a first liquid refrigerant residence range and a second liquid refrigerant residence range below the first liquid refrigerant residence range are set,
The power module is
Switching elements are formed with wide gap semiconductor elements,
Of outer Guo before Symbol compressor, a position corresponding to the first liquid refrigerant reservoir range, attached via a heat transfer member,
To flow a current to the electric motor,
The controller is
With the compressor stopped,
A current is passed through the electric motor by the switching element, and the energization is performed to heat the electric motor,
In accordance with the temperature change rate of the power module, it is estimated whether the liquid level height of the liquid refrigerant of the compressor is the first liquid refrigerant retention range or the second liquid refrigerant retention range < An air conditioner characterized by the above. Before Symbol control unit,
Based on the temperature detected by the temperature detector, the temperature change rate per hour is calculated,
When the rate of temperature change per hour changes during execution of the restraint energization,
The air conditioner according to claim 1 , wherein the power module stops a current flowing through the electric motor. The power module is
3. The air conditioner according to claim 1, wherein a high-frequency phase loss current is allowed to flow during the restraint energization. The power module is
3. The air conditioner according to claim 1, wherein a high-frequency alternating current is passed during the restraint energization.

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