JP4260242B2 - Refrigeration cycle equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration cycle apparatus including a plurality of hermetic compressors connected in parallel to each other, and more particularly, to a refrigeration cycle apparatus using HFC refrigerant and synthetic oil higher in pressure than R22 such as R410A.
[0002]
[Prior art]
In order to be able to control the capacity of the refrigeration cycle in a wide range, a refrigeration cycle apparatus including a plurality of compressors connected in parallel to each other is known.
[0003]
Also, in refrigeration cycle devices used in recent air conditioners and the like, high-pressure HFC (hydrofluorocarbon) refrigerants such as R410A are often used as alternative refrigerants for conventional HCFC (hydrochlorofluorocarbon) refrigerants such as R22. It has become. And when using a HFC refrigerant, it is common to use synthetic oil instead of mineral oil as refrigeration oil on the characteristic.
[0004]
Also, when using a hermetic compressor, in order to keep a sufficient amount of refrigeration oil inside the compressor, an oil separator is provided in the discharge pipe of the compressor and separated from the refrigerant by this oil separator. It has been performed that the refrigerating machine oil is returned to the suction pipe.
[0005]
[Problems to be solved by the invention]
Here, in a hermetic compressor, an AC motor is housed in a hermetic container, and the motor windings constituting the stator of the motor are exposed to the refrigerant and refrigeration oil of the refrigeration cycle. For this reason, a leakage current may flow between the motor winding and the sealed container. The theoretical magnitude I of this leakage current is expressed by the following equation.
[0006]
I = V / (1 / 2πfC) = 2πfC · V
In this equation, V is a voltage, f is a power supply frequency, and C is a capacitance between electrodes when the motor winding and the sealed container are regarded as counter electrodes. And proportional to the dielectric constant of the refrigeration oil.
[0007]
For this reason, if HFC refrigerant and synthetic oil having a relative dielectric constant larger than those of HCFC refrigerant and mineral oil are used as refrigerant and refrigerating machine oil, the above-described capacitance C increases, leading to an increase in leakage current. .
[0008]
In particular, when an inverter power source is used as a power source for driving a compressor, the power source frequency f includes a large number of high frequency components (carrier frequencies) of several kHz that are significantly higher than 50 to 60 Hz of the commercial power source. The leakage current is more likely to increase than in the case of.
[0009]
Such an increase in leakage current may cause problems such as malfunction of an earth leakage breaker or microcomputer device, or electric shock.
[0010]
Also, when multiple sealed compressors are connected in parallel, an oil separator may be provided where the discharge pipes of each compressor are gathered, or an oil separator may be provided for each compressor. From the simultaneous operation of all the compressors to the single operation of one compressor, it is difficult to keep an appropriate amount of refrigeration oil in each compressor in a well-balanced manner. For this reason, problems such as poor lubrication and damage due to a shortage of refrigerating machine oil inside the compressor may occur.
[0011]
The present invention has been made in consideration of such points, and includes a plurality of hermetic compressors connected in parallel to each other, and in a refrigeration cycle apparatus using an HFC refrigerant and synthetic oil higher in pressure than R22, The main purpose is to reduce the leakage current of the compressor and to enable each compressor to always keep the refrigerating machine oil in a well-balanced manner.
[0012]
[Means for Solving the Problems]
The first means includes a plurality of hermetic compressors connected in parallel to each other, uses a HFC refrigerant higher in pressure than R22 as a refrigerant, and uses a synthetic oil as a refrigerating machine oil. The refrigeration cycle apparatus is configured to control operation of at least a part of the compressors using a commercial power source.
[0013]
According to this first means, the leakage current of the compressor is reduced as a whole by controlling the operation of at least a part of the compressor with the commercial power supply, as compared with the case of controlling the operation of all the compressors with the inverter power supply. Can be made.
[0014]
In addition, by providing a plurality of compressors connected in parallel to each other, the capacity of each compressor can be made smaller, and overall capacity control can be performed by the number of operating units of such small capacity compressors. it can. As a result, the supply current value of each compressor driving power supply circuit at the time of small capacity operation can be reduced.
[0015]
The second means is that in the first means, each compressor has a high-pressure vessel to the extent that it is used for a rotary compressor as a hermetic container.
[0016]
According to the second means, in the first means, when an HFC refrigerant having a pressure higher than R22 is used as the refrigerant, the internal pressure of the hermetic container of the compressor becomes higher, but the hermetic container is used for the rotary compressor. By using a high-pressure vessel of a degree, it is possible to reduce refrigerant gas leakage as compared with a low-pressure vessel of a degree used for a general scroll compressor. In addition, since a plurality of compressors having such a high-pressure vessel are connected in parallel, the burden of increasing the internal pressure of the sealed vessel of each compressor is reduced. For this reason, the efficiency and capacity of the entire refrigeration cycle can be improved.
[0017]
In general, HFC refrigerant having a pressure higher than that of R22 has a higher refrigeration capacity than R22. Therefore, by combining with a compressor having a high-pressure vessel as described above, each compressor can be made to have a smaller capacity. .
[0018]
According to a third means, in the first means, at least a part of the compressors whose operation is controlled by the commercial power source is configured to be variable in capacity by mechanical capacity variable means.
[0019]
According to the third means, in the first means, the ability of at least a part of the compressor can be changed by the mechanical ability variable means to perform finer capacity control.
[0020]
According to a fourth means, in the first means, at least a part of the plurality of compressors is configured to be operated and controlled by an inverter power supply, and a leak canceller is connected to the inverter power supply. It is.
[0021]
According to the fourth means, in the first means, when at least a part of the compressors is controlled to operate with variable capacity by the inverter power supply, so that all the compressors are controlled with constant capacity by the commercial power supply. Compared with this, it is possible to perform a capability control with a large change width and fine control.
[0022]
Also, by connecting multiple compressors in parallel, the capacity of each compressor can be made smaller, so the corresponding inverter power supply can be of a lower capacity, facilitating compatibility with harmonics and leakage currents. be able to.
[0023]
Furthermore, by connecting a leak canceller to the inverter power supply, the leakage current itself caused by the inverter power supply can be reduced.
[0024]
A fifth means is the first means, wherein the plurality of compressors are constantly operated with priority, and the operating capacity of the refrigeration cycle during the operation of the first compressor. Each of the second compressors is provided with a low-pressure holding means, and the low-pressure holding means is provided with the second compressor during operation of the first compressor. When the operation of the compressor is stopped, the inside of the second compressor is kept at a lower pressure than the inside of the first compressor.
[0025]
According to the fifth means, in the first means, at the start of the operation of the refrigeration cycle, the operation of the first compressor is started first, and then the second compressor is operated according to the capacity. When the operation of the refrigeration cycle is stopped, the operation is stopped from the second compressor, and then the operation of the first compressor is stopped.
[0026]
As described above, only the first compressor is operated during low-capacity operation of the refrigeration cycle, and the first compressor is stopped last, so that the refrigerant is liquefied inside the first compressor. Therefore, it is not necessary to provide a means for preventing the user from falling asleep, and the driving efficiency can be kept high.
[0027]
On the other hand, with respect to the second compressor, when the operation is stopped, the inside is kept at a lower pressure than the inside of the first compressor by the low-pressure holding means, so that the refrigerant can be prevented from being liquefied and sleeping.
[0028]
The sixth means is the fifth means in which the low-pressure holding means is a check valve provided on the discharge side of the second compressor.
[0029]
Here, by using an HFC refrigerant having a pressure higher than that of R22 as the refrigerant, the pressure difference between the high pressure side and the low pressure side becomes larger, and when the second compressor is stopped, the second compressor is supplied with refrigeration oil from the discharge side. It becomes easy for reversal to occur.
[0030]
Therefore, in the sixth means, in the fifth means, the low pressure holding means is a check valve provided on the discharge side of the second compressor, so that the reversal of the refrigerating machine oil as described above can be prevented. I have to.
[0031]
A seventh means is the same as the sixth means, wherein a thin tube for connecting the discharge side and the suction side of the second compressor is provided.
[0032]
According to the seventh means, in the sixth means, when the second compressor is stopped, the refrigerant reverses until the check valve acts due to the large pressure difference as described above. Even when it occurs, the pressure can be released to the suction side by the thin tube connecting the discharge side and the suction side, and the second compressor can be protected.
[0033]
According to an eighth means, in the first or second means, an outdoor unit having at least the plurality of compressors and an outdoor heat exchanger, an indoor unit having at least an indoor heat exchanger and an indoor fan, and the outdoor Control means for performing dehumidification priority cooling operation by a combination of low-capacity continuous operation by a part of the compressors in the unit and low-speed operation of the indoor blower in the indoor unit Is.
[0034]
According to the eighth means, in the first or second means, by using an HFC refrigerant having a pressure higher than that of R22, the range of change in the refrigerating capacity with respect to the change in the capacity of the compressor can be increased, and a plurality of compressors Since the compressors can be connected in parallel, the capacity of each compressor can be further reduced, so that a low-capacity cooling operation can be performed by low-capacity continuous operation using some compressors. And by performing the dehumidification priority cooling operation by the combination of such a low-capacity cooling operation and the low-speed operation of the indoor blower, comfortable air conditioning with less cool air feeling and a large dehumidifying effect can be performed.
[0035]
According to a ninth means, in the first or second means, an outdoor unit having at least the plurality of compressors and the outdoor heat exchanger is connected in parallel to the outdoor unit, and at least indoor heat exchange is performed respectively. And a plurality of indoor units having an indoor fan.
[0036]
According to the ninth means, the overall capacity control can be performed by changing the number of operating relatively small capacity compressors in the first or second means. Accordingly, appropriate capacity control can be performed over a wide range, and the operation of the refrigeration cycle can always be maintained in a well-balanced manner to increase the operation efficiency.
[0037]
According to a tenth means, in the second means, an oil return hole for returning the refrigerating machine oil inside the closed container to the low-pressure side circuit of the refrigeration cycle is provided in the closed container of each compressor. The lower end of the motor winding in the sealed container is formed at a lower position.
[0038]
According to the tenth means, in the second means, the oil return hole is formed at a position lower than the lower end portion of the motor winding in the sealed container, so that the liquid level of the refrigerating machine oil in the sealed container is always kept at the electric motor level. It can be kept lower than the lower end of the winding. For this reason, the leakage current which flows through refrigerator oil between an electric motor coil | winding and an airtight container can be suppressed.
[0039]
The eleventh means is the tenth means, wherein the low-pressure side circuit is branched into a plurality of suction pipes corresponding to the respective compressors, an auxiliary pipe for connecting the suction pipes, and the auxiliary pipe. A plurality of oil return pipes that connect the oil return holes of the respective compressors and have throttle means are provided.
[0040]
According to the eleventh means, in the tenth means, the refrigerating machine oil of each compressor corresponds to the oil amount corresponding to the liquid level in the sealed container exceeding the height of the oil return hole (excess amount). It is returned to each suction pipe through the auxiliary pipe from the return pipe.
[0041]
This makes it possible for each compressor to always hold the refrigerating machine oil in a well-balanced manner from a part of the plurality of compressors to the entire operation.
[0042]
The twelfth means is that in the eleventh means, the connecting portion of each oil return pipe to the auxiliary pipe is a compressor other than the compressor corresponding to the oil return pipe in the auxiliary pipe. It is provided in a part closer to the side of the.
[0043]
According to the twelfth means, in the eleventh means, the excessive amount of the refrigeration oil returned from a certain compressor through the oil return pipe returns more to the compressors other than the compressor through the auxiliary pipe. Since it becomes easy, the return of the refrigerating machine oil from the compressor with an excessive amount of the refrigerating machine oil to the deficient compressor can be promoted.
[0044]
A thirteenth means is the eleventh means wherein the plurality of compressors are always operated with priority, and the operating capacity of the refrigeration cycle during the operation of the first compressor. The oil return pipe is provided corresponding to only the first compressor. The second compressor is operated or stopped accordingly.
[0045]
According to the thirteenth means, in the eleventh means, when the operation of only the first compressor is shifted to the simultaneous operation with the second compressor, the excessive amount of the refrigerating machine oil in the first compressor. If there is, the excessive amount of refrigeration oil flows out to the oil return pipe, and a part thereof is returned from the auxiliary pipe to the second compressor through the suction pipe. For this reason, when shifting from the operation of only the first compressor to the simultaneous operation with the second compressor, the amount of refrigerating machine oil retained in both compressors can be balanced at an early stage.
[0046]
A fourteenth means is the eleventh means, wherein the plurality of compressors are provided with a first compressor that is always preferentially operated, and an operating capacity of the refrigeration cycle during the operation of the first compressor. Accordingly, the oil return pipe is provided corresponding to only the second compressor.
[0047]
According to the fourteenth means, in the eleventh means, when the operation of only the first compressor is shifted to the simultaneous operation with the second compressor, the excess refrigeration oil is contained in the second compressor. If there is, the excess refrigeration oil flows out to the oil return pipe, and a part thereof is returned from the auxiliary pipe to the first compressor through the suction pipe. For this reason, when shifting from the operation of only the first compressor to the simultaneous operation with the second compressor, the amount of refrigerating machine oil retained in both compressors can be balanced at an early stage.
[0048]
The fifteenth means is any one of the eleventh to fourteenth means, wherein the auxiliary pipe is connected to each suction pipe in a substantially vertical direction.
[0049]
According to the fifteenth means, in any one of the eleventh to fourteenth means, the refrigerating machine oil easily flows in a balanced manner from the auxiliary pipes to the suction pipes due to the action of gravity. Can be effectively distributed.
[0050]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. 1 to 16 are diagrams showing an embodiment of a refrigeration cycle apparatus according to the present invention.
[0051]
[First Embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, the refrigeration cycle apparatus (here, the air conditioner) includes an outdoor unit U1 and two indoor units U2 connected in parallel to the outdoor unit U1.
[0052]
The outdoor unit U1 includes two compressors 1a and 1b connected in parallel to each other, an outdoor heat exchanger 2, a throttle valve 3, a four-way valve 5, and an accumulator 6. Moreover, each indoor unit U2 has the indoor heat exchanger 4 and the indoor air blower 21, respectively. The refrigeration cycle apparatus is configured to perform the cooling operation in the refrigerant flow direction indicated by the solid line arrow in FIG. 1 and to perform the heating operation in the refrigerant flow direction indicated by the broken line arrow by switching the four-way valve 5. .
[0053]
Here, this refrigeration cycle apparatus uses, as a refrigerant, R410A (a mixed refrigerant in which R32 (difluoromethane) and R125 (pentafluoroethane) are mixed by 50 wt% each), which is an HFC refrigerant having a pressure higher than that of R22 (monochlorofluoromethane). use. The pressure of R410A is about 1.4 times and the refrigerating capacity is about 1.5 times that of R22. In addition, as the refrigerating machine oil for lubricating the compressors 1a and 1b, a synthetic oil that matches the characteristics of the HFC refrigerant (for example, has good compatibility with the HFC refrigerant) is used.
[0054]
Here, the two compressors 1a and 1b are operated according to the first compressor 1a that is always preferentially operated and the operation capacity of the refrigeration cycle during the operation of the first compressor 1a. The second compressor 1b is stopped. That is, at the start of the operation of the refrigeration cycle apparatus, the operation of the first compressor 1a is started first, and then the second compressor 1b is operated according to the capacity. When the operation of the refrigeration cycle apparatus is stopped, the operation is first stopped from the second compressor 1b, and then the operation of the first compressor 1a is stopped.
[0055]
Here, a check valve 7 as a low pressure holding means is provided on the discharge side of the second compressor 1b. The check valve 7 serving as the low-pressure holding means is configured so that when the operation of the second compressor 1b is stopped during the operation of the first compressor 1a, the first compressor 1b is compressed inside the second compressor 1b. This is for keeping the pressure lower than the inside of the machine 1a.
[0056]
Further, this refrigeration cycle apparatus is a control means for performing a dehumidification priority cooling operation by a combination of a low-capacity continuous operation only by the first compressor 1a in the outdoor unit U1 and a low-speed operation of the indoor blower 21 in the indoor unit U2. (Not shown).
[0057]
Next, as shown in FIG. 2, the two compressors 1a and 1b are both controlled to operate at a constant capacity by a commercial power supply (three-phase AC power supply) 16 having a constant frequency (for example, 50 Hz or 60 Hz). It has become. In addition, what is shown by the code | symbols 18a and 18b in FIG. 2 is an electromagnetic switch corresponding to each compressor 1a and 1b.
[0058]
In this case, if the capacity of the first compressor 1a is A, and the capacity of the second compressor 1b is B, both compressors 1a, 1b according to the range of the required capacity Q as shown in FIG. The total capacity Q ′ can be changed in two stages: A by single operation of only the first compressor 1a and A + B by simultaneous operation with the second compressor 1b.
[0059]
Further, each of the compressors 1a and 1b is a rotary compressor (rolling piston compressor) having a high-pressure container as the sealed container 11 as shown in FIG. Another type of compressor having a container. As shown in FIG. 4, each of the compressors 1 a and 1 b is provided with an electric motor unit including a rotor 12 and a stator 13 and a compressor unit 14 positioned below the electric motor unit in the sealed container 11. .
[0060]
And each compressor 1a, 1b compresses the refrigerant | coolant suck | inhaled from suction pipe 9a, 9b with the compressor part 14, once discharges it in the airtight container 11, and this is discharged from discharge pipe 8a, 8b of the airtight container 11 upper part. It is comprised so that it may discharge.
[0061]
The refrigerating machine oil O is held at the bottom of the sealed container 11, and the oil return hole is formed on the side surface of the sealed container 11 at a position lower than the lower end of the winding (electric motor winding) 130 of the stator 13. 15 is provided. The oil return hole 15 is for returning the refrigeration oil O inside the sealed container 11 to the low pressure side circuit 9 (see FIG. 1) of the refrigeration cycle.
[0062]
Specifically, as shown in FIG. 1, the low-pressure side circuit 9 of the refrigeration cycle branches into two suction pipes 9a, 9b corresponding to the compressors 1a, 1b, and the compressors 1a, 1b Are provided with oil return pipes 10a and 10b for connecting the oil return holes 15 to the suction pipes 9b and 9a corresponding to the other compressors 1b and 1a, respectively.
[0063]
That is, the refrigeration oil that has flowed out of the oil return hole 15 of the first compressor 1a is sucked into the second compressor 1b from the oil return pipe 10a through the suction pipe 9b, and the oil return hole 15 of the second compressor 1b. The refrigeration oil that has flowed out of the oil is drawn into the first compressor 1a from the oil return pipe 10b through the suction pipe 9a. Each oil return pipe 10a, 10b has a pressure reducing capillary tube (throttle means) 20.
[0064]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to the present embodiment, as shown in FIG. 2, by controlling the operation of both the two compressors 1a and 1b by the commercial power supply 16, one or both of the compressors 1a and 1b can be controlled by the inverter power supply. Compared with the case of operation control, the leakage current of the compressors 1a and 1b can be reduced as a whole.
[0065]
Further, as shown in FIG. 4, the oil return hole 15 is formed at a position lower than the lower end of the motor winding 130 in the sealed container 11, so that the liquid level L of the refrigerating machine oil in the sealed container 11 is always applied to the motor winding. It can be kept lower than the lower end of the line 130. For this reason, it is possible to suppress a leak current flowing through the refrigerator oil between the motor winding 130 and the sealed container 11.
[0066]
For this reason, problems associated with an increase in leakage current can be avoided without particularly providing leakage current reducing means, so that the control circuit can be simplified and the reliability can be improved.
[0067]
Next, when R410A, which is an HFC refrigerant having a pressure higher than that of R22, is used as the refrigerant, the internal pressure of the sealed container 11 of the compressors 1a and 1b becomes higher. However, the high-pressure container that can be used for the rotary compressor As a result, it is possible to reduce the gas leakage of the refrigerant as compared with the case of a low-pressure vessel of a degree used for a general scroll compressor. Moreover, since the two compressors 1a and 1b having such a high-pressure vessel are connected in parallel, the burden of the pressure increase in the sealed vessel 11 of each of the compressors 1a and 1b is reduced. For this reason, the efficiency and capacity of the entire refrigeration cycle can be improved.
[0068]
Further, R410A, which is an HFC refrigerant having a pressure higher than that of R22, has a refrigerating capacity about 1.5 times higher than that of R22. Therefore, by combining with the compressors 1a and 1b having the high-pressure containers as described above, individual compressors can be obtained. 1a and 1b can be of smaller capacity.
[0069]
Further, by providing two compressors 1a and 1b connected in parallel to each other, the capacity of each of the compressors 1a and 1b is further reduced, and depending on the number of operating compressors 1a and 1b having such a small capacity. Overall capacity control can be performed.
[0070]
As a result, the supply current value of the driving power supply 16 for each of the compressors 1a and 1b during the small capacity operation can be reduced.
[0071]
Next, by using R410A, which is an HFC refrigerant having a pressure higher than that of R22, the range of change in the refrigeration capacity with respect to the change in capacity of the compressors 1a, 1b can be increased, and as described above, the individual compressors 1a, 1b Since the capacity can be further reduced, the low-capacity cooling operation can be performed by the low-capacity continuous operation using only the first compressor 1a. And by performing the dehumidification priority cooling operation by the combination of such a low-capacity cooling operation and the low-speed operation of the indoor blower 21, it is possible to perform comfortable air conditioning with less cool air feeling and a large dehumidifying effect.
[0072]
Further, as described above, since the overall capacity control can be performed by changing the number of operating compressors 1a and 1b having relatively small capacities, a wide range of appropriate capacities according to the number of operating indoor units U2. Control can be performed, and the operation of the refrigeration cycle can always be maintained in a well-balanced manner to increase the operation efficiency.
[0073]
Next, only the first compressor 1a is operated at the time of low-capacity operation of the refrigeration cycle, and the first compressor 1a is stopped last, so that the first compressor 1a has a refrigerant inside. It is not necessary to provide means for preventing liquefaction and falling asleep, and the operation efficiency can be kept high.
[0074]
On the other hand, with respect to the second compressor 1b, when the operation is stopped, the inside of the second compressor 1b is kept at a lower pressure than the inside of the first compressor 1a by the check valve 7 as a low-pressure holding means, so that the refrigerant liquefies and stagnates inside. Can be prevented.
[0075]
Here, by using R410A that is an HFC refrigerant having a pressure higher than that of R22 as the refrigerant, the pressure difference between the high-pressure side and the low-pressure side becomes larger, and when the second compressor 1b is stopped, the second compressor 1b Refrigerating machine oil from the discharge side tends to reverse. Therefore, in this embodiment, the low pressure holding means is the check valve 7 provided on the discharge side of the second compressor 1b, so that the reversal of the refrigerating machine oil as described above can be prevented.
[0076]
Of the two compressors 1a and 1b controlled by the commercial power supply 16, for example, the first compressor 1a is returned to a mechanical capacity variable means (not shown) (for example, a part of the discharged refrigerant is returned to the suction side). The capacity may be varied by a re-lace circuit or the like. With such a configuration, the capacity of the compressor 1a can be changed by the mechanical capacity variable means, and finer capacity control can be performed.
[0077]
Moreover, although the case where two compressors 1a and 1b were connected in parallel was described, a total of three or more compressors 1a and 1b may be connected in parallel. Furthermore, although the case where two indoor units U2 are provided in parallel has been described, three or more indoor units U2 may be provided in parallel, or only one indoor unit U2 may be provided. However, when only one indoor unit U2 is provided, the concept of capability control according to the number of operating indoor units U2 described above is naturally not applied.
[0078]
[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 5, the present embodiment is different from the first embodiment in that the operation of the first compressor 1a is controlled by inverter power supplies 16 and 17, and the other configurations are the same as those shown in FIGS. This is the same as the first embodiment shown in FIG.
[0079]
That is, as shown in FIG. 5, the inverter circuit 17 is interposed between the first compressor 1a and the commercial power supply 16, so that the operation of the first compressor 1a is controlled by the inverter power supplies 16 and 17. It has become so. A leak canceller 19 is connected to the inverter power supplies 16 and 17.
[0080]
Here, an example of the leak canceller 19 will be described with reference to FIGS. FIG. 7 shows a circuit (compensation circuit) of the leak canceller 19 that is incorporated in the inverter power supplies 16 and 17. In FIG. 7, the leak canceller 19 includes a secondary winding S provided in a line filter F that detects a zero phase, an amplifying unit using an NPN transistor Tr1 and a PNP transistor Tr2, and a capacitor C1.
[0081]
The leak canceller 19 configured as described above detects the leakage current i3 of the power source by the secondary winding S, amplifies it by the amplifying unit by the transistors Tr1 and Tr2, and supplies the current i1 flowing through the compressor 1a. A compensation current i2 that cancels is applied. As a result, the leakage current i3 flowing to the ground can be made substantially zero.
[0082]
In this case, currents flow in both directions through the transistors Tr1 and Tr2 of the amplifying unit. However, the transistor Tr1 is turned on by a negative current and the transistor Tr2 is turned on by a positive current. The secondary winding S can be made one. The capacitor C1 is for direct current cut and has a function of compensating only for leakage current.
[0083]
Here, the line filter F is a ferrite core in which a copper wire is wound in the same phase, and as shown in FIG. 8, a normal mode noise current (when the load side is considered as a noise generation source, the line filter F flows through a line on one side. The magnetic fields Ms generated by the noise current (is) returning through the opposite line cancel each other.
[0084]
The secondary winding S is wound in the same phase as the winding of the line filter F, detects the common mode noise current flowing in the line filter F (with the same phase), and amplifies it by the transistors Tr1 and Tr2. It is comprised so that it may amplify in a part.
[0085]
Next, how the compensation current i2 flows will be described using a simple circuit shown in FIG. In FIG. 9, the plus-side common mode noise current i1 flows as indicated by the solid line arrow, and the transistor Tr2 is operated by the current detected on the secondary side of the line filter F to cancel the plus-side noise current i1. The compensation current i2 is supplied to make the current i3 flowing to the ground substantially zero.
[0086]
On the other hand, in FIG. 9, the negative-side common mode noise current i1 flows as indicated by the broken-line arrow, operates the transistor Tr1 with the current detected on the secondary side of the line filter F, and cancels the negative-side noise current i1. Such a compensation current i2 is supplied to make the current i3 flowing through the ground substantially zero.
[0087]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to the present embodiment, the operation of the first compressor 1a is variably controlled by the inverter power supplies 16 and 17, so that all the compressors 1a and 1b are controlled and controlled by the commercial power supply 16 with a constant capacity. Thus, it is possible to perform capability control with a large change width and fine control.
[0088]
For example, as shown in FIG. 6, the second compressor 1b is set to a constant capacity B, and the capacity of the first compressor 1a is continuously variable in the range of capacity A1 to A2 (A2 = B + A1) by inverter power supplies 16 and 17. In this case, the total capacity Q ′ of both the compressors 1a and 1b can be continuously changed in the range of A1 to B + A2 according to the required capacity Q.
[0089]
Moreover, as mentioned above, since the capacity | capacitance of each compressor 1a, 1b can be made smaller by connecting several compressor 1a, 1b in parallel, the inverter circuit 17 of the corresponding inverter power supplies 16, 17 can be made more By using a low capacity, it is possible to easily cope with harmonics and leakage current.
[0090]
Furthermore, by connecting the leak canceller 19 as described above to the inverter power supplies 16 and 17, the leak current itself caused by the inverter power supplies 16 and 17 can be reduced as described above.
[0091]
[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, as shown in FIG. 10, the above-mentioned first structure is provided with a thin tube 22 that connects the discharge pipe 8b (discharge side) and the suction pipe 9b (suction side) of the second compressor 1b. Unlike the first embodiment, other configurations are the same as those of the first embodiment shown in FIGS. As this thin tube 22, for example, an inner diameter of 0.8 mm and a total length of 3000 mm are used.
[0092]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to the present embodiment, when the second compressor 1b is stopped, even if a refrigerant reverse phenomenon occurs before the check valve 7 acts due to the large pressure difference as described above, the discharge is performed. Pressure can be relieved to the suction side by the thin tube 22 connecting the tube 8b and the suction tube 9b, and the second compressor 1b can be protected.
[0093]
[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. As shown in FIGS. 11 and 12, the present embodiment is provided with an auxiliary pipe 24 for connecting the suction pipes 9a, 9b to each other, and the oil return pipes 10a, 10b are connected to the auxiliary pipe 24. Unlike the first embodiment, other configurations are the same as those of the first embodiment shown in FIGS.
[0094]
Specifically, as shown in FIGS. 11 and 12, the auxiliary pipe 24 that connects the suction pipes 9a and 9b to each other so as to straddle the branch portions 9c to the suction pipes 9a and 9b of the low-pressure side circuit 9. Is provided. And the oil return pipe | tube 10a and the oil return pipe | tube 10b of the side of the corresponding compressor 1a, 1b are respectively connected to the suction pipe 9a side and the suction pipe 9b side of this auxiliary piping 24.
[0095]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to this embodiment, the refrigerating machine oil of each compressor 1a, 1b is the amount that the liquid level L in the sealed container 11 exceeds the height of the oil return hole 15 (excess) (see FIG. 4), The corresponding oil return pipes 10a and 10b are returned to the suction pipes 9a and 9b through the auxiliary pipe 24. This makes it possible for each of the compressors 1a and 1b to always hold the refrigerating machine oil in a well-balanced manner, from an independent operation of only the first compressor 1a to a simultaneous operation with the second compressor 1b. .
[0096]
The auxiliary pipe 24 shown in FIG. 12 is connected to the suction pipes 9a and 9b in a substantially horizontal direction. However, as shown in FIG. 13, the auxiliary pipe 24 is connected to the suction pipes 9a and 9b. In this case, the connection may be made in a substantially vertical direction. By doing so, the refrigerating machine oil easily flows in a balanced manner from the auxiliary pipe 24 into the suction pipes 9a and 9b due to the action of gravity, so that the refrigerating machine oil returned to the compressors 1a and 1b is effectively distributed. be able to.
[0097]
[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described with reference to FIG. In the present embodiment, as shown in FIG. 14, the connecting portions 24 a and 24 b of the oil return pipes 10 a and 10 b to the auxiliary pipe 24 are compressors corresponding to the oil return pipes 10 a and 10 b in the auxiliary pipe 24. Unlike the fourth embodiment in that it is provided closer to the other compressor 1b, 1a side than the side of 1a, 1b, other configurations are the same as those shown in FIGS. This is the same as in the fourth embodiment.
[0098]
That is, the connecting portion 24a of the oil return pipe 10a to the auxiliary pipe 24 is connected to the second compressor 1b (suction of the auxiliary pipe 24 rather than the first compressor 1a side corresponding to the oil return pipe 10a. It is provided closer to the tube 9b) side. Further, the connecting portion 24b of the oil return pipe 10b to the auxiliary pipe 24 is connected to the first compressor 1a (suction of the auxiliary pipe 24 from the side of the second compressor 1b corresponding to the oil return pipe 10b). It is provided in a portion closer to the tube 9a) side.
[0099]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to the present embodiment, the excessive amount of the refrigeration oil returned from the one compressor 1a, 1b through the oil return pipes 10a, 10b returns more toward the other compressor 1b, 1a through the auxiliary pipe 24. Since it becomes easy, return of the refrigerating machine oil to the compressor 1b, 1a of the one where the quantity of refrigerating machine oil is insufficient from the compressor 1a, 1b of the surplus can be promoted.
[0100]
[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described with reference to FIG. In the present embodiment, as shown in FIG. 15, the oil return pipe 10a is provided only corresponding to the first compressor 1a, and the oil return pipe 10b corresponding to the second compressor 1b is omitted. Unlike the fifth embodiment, the other configurations are the same as those of the fifth embodiment shown in FIGS. 11 to 13. In this case, the oil return pipe 10 a is connected to the central portion of the auxiliary pipe 24.
[0101]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to the present embodiment, when the first compressor 1a alone operation is shifted to the simultaneous operation with the second compressor 1b, the excess compressor oil is present in the first compressor 1a. The excess refrigeration oil flows out to the oil return pipe 10a, and about half of it is returned from the auxiliary pipe 24 to the second compressor 1b through the suction pipe 9b. For this reason, when shifting from the single operation of only the first compressor 1a to the simultaneous operation with the second compressor 1b, the amount of refrigerating machine oil retained in both the compressors 1a and 1b can be balanced at an early stage.
[0102]
[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described with reference to FIG. In the present embodiment, as shown in FIG. 16, the oil return pipe 10b is provided only corresponding to the second compressor 1b, and the oil return pipe 10a corresponding to the first compressor 1a is omitted. Unlike the fifth embodiment, the other configurations are the same as those of the fifth embodiment shown in FIGS. 11 to 13. Also in this case, the oil return pipe 10 b is connected to the central portion of the auxiliary pipe 24.
[0103]
Next, the effect of this embodiment which consists of such a structure is demonstrated. According to the present embodiment, when the single compressor 1a alone operation is shifted to the simultaneous operation with the second compressor 1b, the excess compressor oil is present in the second compressor 1b. The excess refrigeration oil flows out to the oil return pipe 10b, and about half of it is returned from the auxiliary pipe 24 to the first compressor 1a through the suction pipe 9a. For this reason, when shifting from the single operation of only the first compressor 1a to the simultaneous operation with the second compressor 1b, the amount of refrigerating machine oil retained in both the compressors 1a and 1b can be balanced at an early stage.
[0104]
【The invention's effect】
According to the present invention, it is possible to reduce the leakage current of the compressor as a whole by controlling the operation of at least a part of the compressor with a commercial power supply, as compared with the case of controlling the operation of all the compressors with an inverter power supply. it can. For this reason, problems associated with an increase in leakage current can be avoided without particularly providing leakage current reducing means, so that the control circuit can be simplified and the reliability can be improved.
[0105]
Furthermore, according to the inventions of claims 11 to 15, the refrigeration oil of each compressor is supplied from the corresponding oil return pipe to the auxiliary pipe by the amount that the liquid level in the sealed container exceeds the height of the oil return hole. Is returned to each suction pipe. This makes it possible for each compressor to always hold the refrigerating machine oil in a well-balanced manner from a part of the plurality of compressors to the entire operation.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a first embodiment of a refrigeration cycle apparatus according to the present invention.
FIG. 2 is a circuit diagram showing a relationship between a compressor and a driving power source of the refrigeration cycle apparatus shown in FIG.
FIG. 3 is a graph showing capacity control by a combination of constant capacity compressors in the refrigeration cycle apparatus shown in FIG. 1;
4 is a longitudinal sectional view schematically showing an internal structure of a compressor in the refrigeration cycle apparatus shown in FIG.
FIG. 5 is a circuit diagram showing a relationship between a compressor and a power source in a second embodiment of the refrigeration cycle apparatus according to the present invention.
6 is a graph showing capacity control by a combination of a constant capacity compressor and a variable capacity compressor in the refrigeration cycle apparatus shown in FIG. 5;
7 is a circuit diagram showing a leak canceller in a state incorporated in an inverter power supply in the refrigeration cycle apparatus shown in FIG.
8 is a partial circuit diagram for explaining the principle of secondary detection of the line filter in the circuit shown in FIG.
9 is a simplified circuit diagram for explaining how a current flows in the circuit shown in FIG. 7;
FIG. 10 is a system diagram showing an essential part of a third embodiment of a refrigeration cycle apparatus according to the present invention.
FIG. 11 is a system diagram showing an essential part of a fourth embodiment of a refrigeration cycle apparatus according to the present invention.
12 is a perspective view showing a low-pressure side circuit portion of the refrigeration cycle apparatus shown in FIG. 11. FIG.
13 is a perspective view showing a modified example of the low-voltage side circuit portion shown in FIG. 12. FIG.
FIG. 14 is a system diagram showing an essential part of a fifth embodiment of a refrigeration cycle apparatus according to the present invention.
FIG. 15 is a system diagram showing an essential part of a sixth embodiment of a refrigeration cycle apparatus according to the present invention.
FIG. 16 is a system diagram showing an essential part of a refrigeration cycle apparatus according to a seventh embodiment of the present invention.
[Explanation of symbols]
U1 outdoor unit
U2 indoor unit
1a First compressor
1b Second compressor
11 Sealed container
130 Motor winding
15 Oil drain hole
2 outdoor heat exchanger
3 Expansion valve
4 indoor heat exchangers
5 Four-way valve
7 Check valve (low pressure holding means)
8a, 8b Discharge pipe
9 Low voltage side circuit
9a, 9b Suction pipe
10a, 10b Oil return pipe
16 Commercial power supply (three-phase AC power supply)
17 Inverter circuit
16,17 Inverter power supply
19 Leak Canceller
20 Aperture means
21 Indoor blower
22 tubules
24 Auxiliary piping

Claims (9)

And a plurality of hermetic compressors which are connected in parallel with each other, and high-pressure HFC refrigerants than R22 that is used as a refrigerant compressed in the compressor, synthetic oil used as refrigerating machine oil for lubrication of the compressor And comprising
In order to control the operation of at least one of the compressors by an inverter power supply and to suppress a leakage current that is increased by using the HFC refrigerant and the synthetic oil, at least one single compressor refrigeration cycle apparatus characterized by being configured to control operation by the commercial power supply.   2. The refrigeration cycle apparatus according to claim 1, wherein each compressor has a high-pressure vessel that can be used for a rotary compressor as a closed vessel. The plurality of compressors are operated or stopped according to the operating capacity of the refrigeration cycle during the operation of the first compressor, which is controlled by an inverter power supply that is always operated with priority. A second compressor whose operation is controlled by a commercial power source ,
A low pressure holding means is provided for each second compressor, and the low pressure holding means is arranged so that when the operation of the second compressor is stopped during the operation of the first compressor, the second compression is performed. The refrigeration cycle apparatus according to claim 1, wherein the interior of the compressor is configured to be kept at a lower pressure than the interior of the first compressor. The refrigeration cycle apparatus according to claim 3 , wherein the low-pressure holding means is a check valve provided on the discharge side of the second compressor. The refrigeration cycle apparatus according to claim 4, further comprising a thin tube that connects a discharge side and a suction side of the second compressor. An outdoor unit having at least the plurality of compressors and outdoor heat exchanger,
Together are connected in parallel to the outdoor unit, plural indoor units and at least the indoor heat exchanger and the indoor blower, respectively, the refrigeration cycle according to any one of claims 1 to 5, characterized in that with a capital apparatus. The airtight container of each compressor is provided with an oil return hole for returning the refrigeration oil inside the airtight container to the low pressure side circuit of the refrigeration cycle,
The refrigeration cycle apparatus according to any one of claims 1 to 6 , wherein the oil return hole is formed at a position lower than a lower end portion of the motor winding in the sealed container. The low-pressure side circuit is branched into a plurality of suction pipes corresponding to each compressor,
An auxiliary pipe that connects these suction pipes, and a plurality of oil return pipes that connect the auxiliary pipe and the oil return hole of each compressor and have a throttle means are provided. Item 8. The refrigeration cycle apparatus according to Item 7 . The connection portion of each oil return pipe to the auxiliary pipe is provided in a portion of the auxiliary pipe that is closer to the other compressor side than the compressor side corresponding to the oil return pipe. The refrigeration cycle apparatus according to claim 8 .

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