JP5001730B2 - Refrigeration equipment - Google Patents

Description

  The present invention relates to a refrigeration apparatus in which a plurality of compressors connected in parallel are independently operated one by one, and particularly to a refrigeration apparatus suitable for application to a transport refrigeration apparatus mounted on a refrigeration vehicle or the like. Is.

  Transportation refrigeration equipment mounted on a refrigerated vehicle can be roughly divided into two types: a sub-engine system equipped with a dedicated engine for driving a compressor, and a direct connection system for driving a compressor by a vehicle running engine. There is. In the case of the direct connection method, while the vehicle is running, the compressor can be driven by the driving engine to perform the cooling operation, but when the pre-cooling operation or the cold insulation operation is performed with the vehicle stopped, the driving engine is also stopped. In addition to the compressor driven by the traveling engine, a so-called standby motor-driven compressor that is driven by a commercial power supply is installed, so that a pre-cooling operation and a cold insulation operation can be performed even when the traveling engine is stopped. .

  In the refrigeration apparatus equipped with the standby motor-driven compressor, a plurality of compressors are connected in parallel during one refrigeration cycle. However, the plurality of compressors are not operated at the same time, and each of them is operated alone. In this refrigeration cycle, a common accumulator having a plurality of refrigerant outflow pipes provided with oil return holes in a low-pressure gas pipe is installed, and a driving engine-driven compressor is connected to the accumulator via the plurality of refrigerant outflow pipes. And a standby motor-driven compressor connected in parallel. Thus, an example of a refrigeration apparatus in which a plurality of compressors are connected in parallel using a common accumulator is disclosed in Patent Document 1.

In the above-described direct-coupled transport refrigeration system, the compressor driven by the traveling engine usually has a drive shaft protruding outside the housing and is driven by obtaining power from the traveling engine via an electromagnetic clutch. The mist lubrication type open type compressor is used, and the motor driven compressor for standby is a forced lubrication system with an oil sump in a housing driven by an electric motor driven by electric power from a commercial power source The electric compressor is used. This is to make the compressor suitable for the drive source. In addition, compressors of different lubrication systems are used because the mist lubrication compressors that can be reduced in size are used as traveling engine-driven compressors installed in narrow engine rooms, and there is a relatively large margin under the chassis. This is because a forced lubrication type compressor having a highly reliable oil sump is used as a compressor installed in a certain space.
WO02 / 073036 (FIGS. 10 to 12)

  However, in a refrigeration system in which a plurality of compressors with different lubrication methods are connected in parallel via a common accumulator, and each compressor is operated independently, the lubrication method of each compressor is different. The oil circulation rate [ratio of the mass flow rate of lubricating oil to the total mass flow rate (refrigerant flow rate + lubricating oil flow rate) (%)] was also different, and the compressor using the mist lubrication method was operated. The oil circulation rate is larger at the time, and the oil circulation rate is smaller when the compressor employing the forced lubrication method is operated.

For this reason, when a plurality of compressors are alternately operated, during operation of a compressor with a large oil circulation rate, a large amount of lubricating oil is circulated in the refrigeration cycle, whereas compression with a low oil circulation rate is performed. When the machine is operated, the lubricating oil circulated in the refrigeration cycle is gradually accumulated in the oil sump in the compressor having a low oil circulation rate. A situation occurs where the amount of lubricating oil circulating in the cycle is insufficient.
As a countermeasure, it is conceivable that a compressor with a low oil circulation rate will be filled with an amount of oil that can be held in the sump, but the amount of oil in the cycle will be excessive, which will not only add extra cost, but will also improve system efficiency. There is a problem of causing a decrease. Also, in small-capacity machines where the ratio of the amount of lubricating oil to the amount of refrigerant increases, the refrigerant stagnates in the lubricating oil stored in the oil sump in the compressor, resulting in insufficient capacity due to insufficient circulating refrigerant. There is.

  The present invention has been made in view of such circumstances, and even when a plurality of compressors having different lubrication methods are alternately operated one by one, each compressor does not fall short of lubricating oil. An object of the present invention is to provide a refrigeration apparatus that can operate normally while properly lubricating the machine.

In order to solve the above problems, the refrigeration apparatus of the present invention employs the following means.
That is, in the refrigeration apparatus according to the present invention, an accumulator having a plurality of refrigerant outflow pipes provided with oil return holes is installed in the low-pressure gas pipe of the refrigeration cycle, and one accumulator is connected to the accumulator via the refrigerant outflow pipe. A plurality of compressors that are independently operated are connected in parallel, and the plurality of compressors are compressors having different lubrication methods, and are connected to the refrigerant outlet pipes. The oil return holes provided are arranged at different height positions corresponding to the plurality of compressors, and the compressor adopting a lubrication system having a large oil circulation rate is located at a position where the oil return holes are low. The compressor, which is connected to the provided refrigerant outlet pipe side and employs a lubrication method with a low oil circulation rate, is connected to the refrigerant outlet pipe side provided with the oil return hole at a high position. The Characterized in that that.

  According to the present invention, when one compressor adopting a lubrication system with a low oil circulation rate connected to a refrigerant outflow pipe provided at a high position of the oil return hole is discharged from the compressor to the refrigeration cycle together with the refrigerant. After the lubricating oil circulates in the refrigeration cycle, it flows into the accumulator and is stored in the accumulator up to the level of the oil return hole disposed at least at a high position. For this reason, the lubricating oil circulated in the refrigeration cycle does not move to one compressor side and is not stored in the inside thereof. Here, the oil circulation rate (OC%) is the ratio of the mass flow rate of the lubricating oil to the total mass flow rate (refrigerant flow rate + lubricating oil flow rate). On the other hand, when one compressor is stopped and another compressor that employs a lubrication system with a high oil circulation rate is operated, the lubricant stored in the accumulator is circulated through the refrigeration cycle as described above. The other compressor is lubricated by the circulation. As a result, when any of the compressors is operated, there is no shortage of refueling, and a plurality of compressors having different lubrication methods can be normally operated while being properly lubricated. Moreover, since it is not necessary to fill the lubricating oil excessively in consideration of the accumulation in the compressor, the filling amount of the lubricating oil can be reduced. Therefore, it is possible to prevent a reduction in system efficiency due to excessive filling of lubricating oil, and in a small capacity machine in which the lubricating amount is relatively large with respect to the refrigerant amount, the refrigerant is contained in the lubricating oil excessively stored in the compressor. As a result of falling asleep, it is possible to prevent a situation where the amount of circulating refrigerant becomes insufficient and the capacity is insufficient.

  In the refrigeration apparatus of the present invention, in the above refrigeration apparatus, the plurality of refrigerant outflow pipes are configured by U-shaped tubes, and the oil return holes provided in the vicinity of the lowermost portion of each U-shaped tube are different from each other. It is characterized by being arranged in the vertical position.

  According to the present invention, in the accumulator in which the refrigerant outflow pipe is constituted by a U-shaped pipe, the oil return holes provided in the vicinity of the lowermost part of each U-shaped pipe are arranged at different height positions, When operating a single compressor that employs a small lubrication system, the lubricant can be stored in the accumulator up to the level of the oil return hole located at a high position. During operation of the other compressors employed, it can be circulated through the refrigeration cycle to lubricate the other compressors. Therefore, when any compressor is operated, there is no shortage of refueling, and the compressor can be operated normally.

  Further, the refrigeration apparatus of the present invention is the above refrigeration apparatus, wherein the plurality of refrigerant outflow pipes are constituted by insertion pipes inserted into the accumulator from the bottom thereof, and are provided in the middle of the respective insertion pipes. The oil return holes are arranged at different height positions.

  According to the present invention, in the accumulator in which the refrigerant outflow pipe is constituted by the insertion pipe inserted into the accumulator from the bottom, the oil return holes provided in the middle of each insertion pipe are arranged at different height positions. Therefore, when operating one compressor that employs a lubrication system with a low oil circulation rate, it is possible to store the lubricating oil in the accumulator up to the level of the oil return hole arranged at a high position. During operation of another compressor that employs a lubrication method with a high rate, it is possible to circulate through the refrigeration cycle and lubricate the other compressor. Therefore, when any compressor is operated, there is no shortage of refueling, and the compressor can be operated normally.

  In the refrigeration apparatus according to the present invention, an accumulator having a plurality of refrigerant outflow pipes provided with oil return holes is installed in a low-pressure gas pipe of a refrigeration cycle, and one accumulator is provided via the refrigerant outflow pipe. A plurality of compressors that are operated independently are connected in parallel, and the plurality of compressors are compressors having different lubrication methods, respectively. The refrigerant outflow pipe to the compressor adopting a lubrication system with a low oil circulation rate is provided with an oil separator that separates the lubricating oil in the refrigerant at the outlet portion thereof in communication with the reservoir of the accumulator. It is characterized by.

  According to the present invention, during operation of one compressor adopting a lubrication system having a low oil circulation rate connected to a refrigerant outflow pipe provided with an oil separator at the outlet, the refrigerant is discharged from the compressor to the refrigeration cycle. After the lubricating oil circulates in the refrigeration cycle, it flows into the accumulator. This lubricating oil is sucked into the compressor side by a certain amount from the oil return hole provided in the refrigerant outflow pipe together with the refrigerant, but is separated by the oil separator provided in the outlet portion of the refrigerant outflow pipe, and the accumulator side The lubricating oil is stored up to the same level as the liquid level. For this reason, the lubricating oil circulated in the refrigeration cycle does not move to one compressor side and is not stored in the inside thereof. On the other hand, when one compressor is stopped and another compressor adopting a lubrication method with a high oil circulation rate is operated, the lubricating oil stored in the oil separator and accumulator is circulated to the refrigeration cycle. The other compressors are lubricated by the circulation of the lubricating oil. Therefore, when any of the compressors is operated, there is no shortage of refueling, and a plurality of compressors having different lubrication methods can be normally operated while being properly lubricated. Moreover, since it is not necessary to fill the lubricating oil excessively in consideration of the accumulation in the compressor, the filling amount of the lubricating oil can be reduced. Therefore, it is possible to prevent a reduction in system efficiency due to excessive filling of lubricating oil, and in a small capacity machine in which the lubricating amount is relatively large with respect to the refrigerant amount, the refrigerant is contained in the lubricating oil excessively stored in the compressor. As a result of falling asleep, it is possible to prevent a situation where the amount of circulating refrigerant becomes insufficient and the capacity is insufficient.

  Furthermore, in the refrigeration apparatus of the present invention, in any one of the above-described refrigeration apparatuses, at least one of the plurality of compressors is of a mist lubrication system having a high oil circulation rate in which lubricating oil is circulated and lubricated together with the refrigerant. At least one other compressor connected to the refrigerant outlet pipe provided with the oil return hole at a high position or the refrigerant outlet pipe provided with the oil separator has an oil reservoir in the housing. And a forced lubrication type compressor having a low oil circulation rate in which the lubricating oil in the oil sump is forcibly supplied and lubricated.

  According to the present invention, a compressor connected to a refrigerant outflow pipe provided with a high oil return hole or a refrigerant outflow pipe provided with an oil separator is provided with an oil circulation whose housing has an oil sump. It is considered to be one compressor with a low-force forced lubrication system. During operation of this one compressor, the lubricating oil circulated in the refrigeration cycle is stored in the accumulator and / or oil separator, so that the lubricating oil moves to the one compressor side and the oil reservoir in its housing It will not be stored in. As a result, the amount of lubrication necessary and sufficient to lubricate the other compressor of the mist lubrication system in the refrigeration cycle even when one compressor is stopped and the other compressor of the mist lubrication system is operated. Oil can be circulated. Accordingly, when any compressor is operated, it can be operated normally while being properly lubricated.

  Furthermore, the refrigeration apparatus of the present invention is the above-described refrigeration apparatus, wherein the mist lubrication type compressor includes a drive shaft that protrudes to the outside of the housing, and is opened by obtaining power from a traveling engine of the refrigeration vehicle. The forced lubrication type compressor is an electric compressor that is provided with an oil reservoir in a housing and is driven by an electric motor that uses electric power from a commercial power source as a drive source.

According to the present invention, the mist lubrication type compressor is an open type compressor driven by a traveling engine, and the forced lubrication type compressor has an oil sump in the housing and drives electric power from a commercial power source. Since the electric compressor is driven by an electric motor as a source, a compressor of a type suitable for being driven by a traveling engine and a commercial power source, which are a plurality of driving sources, respectively. In other words, a compressor installed in a narrow engine room can be easily installed as a mist-lubricated open-type compressor that can be reduced in size, and a compressor installed in a relatively roomy space such as under the chassis of a vehicle. The reliability of lubrication can be ensured as a forced lubrication type compressor equipped with an oil sump.
The above electric compressor is either a hermetic electric compressor with a built-in electric motor in a housing, a semi-hermetic electric compressor, or a compressor driven by a separate electric motor. May be.

  According to the refrigeration apparatus of the present invention, when the compressor having a low oil circulation rate is operated, the lubricating oil discharged from the compressor to the refrigeration cycle side together with the refrigerant can be stored in the accumulator and / or the oil separator. Oil can be circulated through the refrigeration cycle when operating a compressor with a high oil circulation rate, and the compressor with a high oil circulation rate can be lubricated, so there will be no shortage of oil supply when any compressor is operated. A plurality of compressors having different lubrication methods can be operated normally while being properly lubricated. In addition, it is not necessary to fill the lubricating oil excessively in consideration of accumulation in the compressor, and the amount of lubricating oil can be reduced, thereby preventing a decrease in system efficiency due to excessive filling of the lubricating oil. In a small capacity machine with a relatively large amount of lubrication relative to the amount of refrigerant, the refrigerant stagnates in the lubricating oil excessively stored in the compressor, resulting in a shortage of circulating refrigerant and insufficient capacity. Can be prevented from falling into

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 4.
FIG. 1 shows a refrigeration cycle diagram of the refrigeration apparatus according to the first embodiment of the present invention. This refrigeration apparatus 1 is a direct-connection transport refrigeration apparatus mounted on a refrigeration vehicle, and includes two compressors 2 and 3 that compress refrigerant, and a condenser 4 that condenses and liquefies compressed high-temperature and high-pressure refrigerant. Separating the liquefied high-pressure refrigerant into a low-pressure gas-liquid two-phase refrigerant by an expansion valve 5; an evaporator 6 for evaporating the gas-liquid two-phase refrigerant; It has a refrigeration cycle 9 constituted by connecting an accumulator 7 for sucking only the gas refrigerant into the compressor through a refrigerant pipe 8.

  The accumulator 7 is provided with two refrigerant outflow pipes 10 and 11, and suction pipes 8 </ b> A and 8 </ b> B of two compressors 2 and 3 are respectively connected to the two refrigerant outflow pipes 10 and 11. The two compressors 2 and 3 are connected in parallel to each other via an accumulator 7 common to the refrigeration cycle 9. Check valves 12 and 13 are provided on the discharge pipes 8C and 8D of the two compressors 2 and 3, respectively. The two compressors 2 and 3 are not operated at the same time, but are individually operated one by one.

  The compressor 2 is installed in the engine room of the refrigerated vehicle, and is driven by the vehicle traveling engine 14 via the electromagnetic clutch 15. As this compressor 2, there is used an open type compressor 2 that does not have an oil sump or a drive source in a housing in which a compression mechanism is accommodated and can be reduced in size and weight. As is well known, the open type compressor 2 is configured such that a drive shaft projects from the housing to the outside, and is driven by obtaining power from the traveling engine 14 by the on / off of an electromagnetic clutch 15 provided on the drive shaft. Further, in the lubrication system of the open type compressor 2, the lubricating oil is dissolved in the refrigerant and circulated through the refrigeration cycle 9 together with the refrigerant, and the required portion of the compressor is defined by the mist-like lubricating oil contained in the suction gas refrigerant. A known mist lubrication method for lubrication is employed.

  The compressor 3 is installed in a space below the chassis of the vehicle and is a standby compressor that is operated during a pre-cooling operation or a cold insulation operation in which the traveling engine 14 is stopped. An electric motor-driven electric compressor 3 using a power obtained from a commercial power supply via a power cable 16 as a drive source is used. The standby electric compressor 3 is driven by a hermetic electric compressor or semi-hermetic electric compressor constructed by integrating an electric motor in a known housing, or by a separate electric motor. Any one of the electric compressors can be used. Further, as a lubrication method of the standby electric compressor 3, a well is provided in which an oil sump is provided in a compressor housing (not shown), and the lubricating oil filled in the oil sump is forcibly supplied to a required portion by a pump or the like to lubricate. The forced lubrication method is adopted.

  Note that the oil circulation rate of the compressor 2 adopting a mist lubrication system that circulates the lubricating oil together with the refrigerant to the refrigeration cycle side to lubricate the compressor [the mass flow rate of the lubricating oil with respect to the total mass flow rate (refrigerant flow rate + lubricating oil flow rate). Ratio (OC%)] is larger than the oil circulation rate of the compressor 3 adopting the forced lubrication system in which the lubricating oil is rotated inside the compressor, and OC% of the mist lubrication system> OC% of the forced lubrication system Are in a relationship.

  The condenser 4 is installed at a suitable location outside the refrigerator mounted on the refrigerated vehicle, and heat-exchanges between the vehicle running wind and air blown from a blower fan (not shown), and cools the refrigerant to condense and liquefy. It bears the function to make it. Moreover, the evaporator 4 is installed inside the refrigerator or facing the refrigerator, and has a function of heat-exchanging the internal air and the refrigerant circulated by a blower fan (not shown) to cool the internal air. It is what you bear.

  As described above, the accumulator 7 includes the two refrigerant outflow pipes 10 and 11 and is configured to be shared by the two compressors 2 and 3. As shown in FIG. 2, the two refrigerant outflow pipes 10, 11 are configured by U-shaped pipes 17, 18, and oil return holes 19, 20 are located near the lowermost portions of the U-shaped pipes 17, 18, respectively. Is provided. The oil return holes 19 and 20 are disposed at different height positions. That is, the oil return hole 20 provided in the U-shaped pipe 18 corresponding to the forced lubrication type compressor 3 having a small oil circulation rate (OC%) is compressed by a mist lubrication method having a large oil circulation rate (OC%). The oil return hole 19 provided in the U-shaped tube 17 corresponding to the machine 2 is disposed at a position higher than the H dimension. This H dimension is the amount of lubricating oil required in the system when the compressor 2 is operated, and the amount of lubricating oil required in the system when the compressor 3 for standby is operated. The height is equivalent to the volume that can hold the difference.

Next, the operation of the refrigeration apparatus having the above-described configuration will be described.
FIG. 1 shows a state where the compressor 2 is driven by the traveling engine 14 and the cooling operation is performed. The high-temperature and high-pressure refrigerant gas compressed by the compressor 2 and discharged to the refrigeration cycle 9 side through the discharge pipe 8C and the check valve 12 is cooled by the condenser 4 and condensed and liquefied, and then decompressed by the expansion valve 5 As a result, it becomes a low-pressure gas-liquid two-phase refrigerant and reaches the evaporator 6. This refrigerant absorbs heat from the air in the refrigerator in the evaporator 6 and is evaporated, and is used for cooling the air in the refrigerator. The gas refrigerant evaporated in the evaporator 6 flows into the accumulator 7, and after the liquid component contained in the refrigerant is separated, only the gas refrigerant is composed of the U-shaped pipe 17 and the refrigerant outflow pipe 10 and the suction pipe 8A. Is sucked into the compressor 2 through the compressor and compressed again. By repeating this, the inside of the refrigerator is cooled.

  During the above cooling operation, the compressor 2 is lubricated by a mist-like lubricating oil circulated in the refrigeration cycle 9 together with the refrigerant. During the operation of the compressor 2 adopting the mist lubrication method, a large amount of lubricating oil is circulated in the refrigeration cycle 9 because the oil circulation rate (OC%) is large. This state is shown in FIG. 1 as a state in which a large amount of lubricating oil O stays in the condenser 4 and the evaporator 6. The lubricating oil circulating in the refrigeration cycle 9 is once separated in the accumulator 7 and then sucked into the compressor 2 by a certain amount from the oil return hole 19 provided in the lowermost part of the U-shaped pipe 17 to be compressed. The machine 2 is used for lubrication.

  On the other hand, when the pre-cooling operation or the cold insulation operation is performed in the standby state, the traveling engine 14 is stopped, so that the standby electric compressor 3 is driven by an electric motor using a commercial power source as a driving source. Driving is performed. The state of this cooling operation is shown in FIG. In this case, since the operation is performed using the compressor 3 adopting the forced lubrication method having a small oil circulation rate (OC%), the amount of lubricating oil circulated in the refrigeration cycle 9 is naturally reduced (as shown in FIG. 3). (Refer to the staying state of the lubricating oil O in the condenser 4 and the evaporator 6). Further, the oil return hole 20 provided in the U-shaped pipe 18 constituting the refrigerant outflow pipe 11 to which the compressor 3 is connected is higher than the oil return hole 19 provided in the U-shaped pipe 17 by the H dimension. Therefore, the lubricating oil O that circulates in the refrigeration cycle 9 and flows into the accumulator 7 is accumulated in the accumulator 7 at least until it reaches the level of the oil return hole 20.

  This prevents the amount of lubricating oil corresponding to the difference in the oil circulation rate (OC%) between the compressor 2 and the compressor 3 from moving to the compressor 3 side and being stored in the oil sump provided in the housing. Then, the lubricating oil O can be held in the accumulator 7 (see FIG. 3). Then, when the pre-cooling operation or the cold-retaining operation is completed and the driving engine 14 is switched to the cooling operation for driving the compressor 2, the lubricating oil held in the accumulator 7 is again refrigerated as shown in FIG. It is circulated in cycle 9. For this reason, a sufficient and sufficient amount of lubricating oil can be circulated in the refrigeration cycle 9 to lubricate the mist lubricated compressor 2.

Thus, according to the present embodiment, the following operational effects are obtained.
When the forced lubrication type standby compressor 3 having a low oil circulation rate is operated, a certain amount of the lubricating oil discharged from the compressor 3 together with the refrigerant and circulated in the refrigeration cycle 9 is accumulated in the accumulator 7. It can prevent moving to the compressor 3 side and being stored in the inside. Then, the lubricating oil stored in the accumulator 7 is circulated again to the refrigeration cycle 9 when the mist lubrication type compressor 2 having a large oil circulation rate is operated, and used for lubricating the compressor 2 having a high oil circulation rate. Therefore, when any of the compressors 2 and 3 is operated, there is no shortage of refueling, and a plurality of compressors 2 and 3 having different lubrication methods can be operated normally.

  Moreover, it is not necessary to preliminarily fill the lubricating oil in consideration of the fact that the lubricating oil is accumulated in the forced-compression standby compressor 3. For this reason, the filling amount of lubricating oil can be reduced. Accordingly, it is possible to prevent a reduction in system efficiency due to excessive filling of lubricating oil, and in a small capacity machine in which the lubricating amount is relatively large with respect to the refrigerant amount, the lubricating oil accumulated excessively in the standby compressor 3 It is possible to avoid a situation where the amount of the refrigerant circulating in the refrigeration cycle 9 becomes insufficient and the capacity falls due to the refrigerant being melted and sleeping.

  Furthermore, since the open engine 2 of a mist lubrication system that can be made compact is used for the traveling engine driven compressor 2 installed in a narrow engine room, installation in a narrow space can be facilitated. In addition, since the forced lubrication type electric compressor 3 having an oil sump driven by an electric motor is used for the compressor 3 installed in a relatively roomy space such as below the chassis, the lubrication performance is improved. Reliability can be ensured.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
The present embodiment differs from the first embodiment in the configuration of the two refrigerant outlet pipes 30 provided in the accumulator 7 and the configuration of the oil separator 31. Since other points are the same as those in the first embodiment, description thereof will be omitted.
In this embodiment, the two refrigerant outflow pipes 30 constituting the accumulator 7 have U-shaped pipes (oil return holes 19 shown in FIG. 2) having the same configuration in which oil return holes (not shown) are provided at the same level position. The same configuration as the U-shaped tube 17). An oil separator 31 for separating lubricating oil contained in the refrigerant sucked into the compressor 3 is provided at the outlet of the refrigerant outflow pipe 30 to which the standby compressor 3 is connected. 31 is communicated with a liquid reservoir of the accumulator 7 by a communication pipe 32.

  With the above configuration, the lubricating oil separated by the accumulator 7 is sucked from the oil return hole (not shown) of the refrigerant outflow pipe 30 by a fixed amount at the time of the precooling operation or the cold insulation operation for driving the compressor 3 for standby. The lubricating oil is separated in the oil separator 31. Since the oil separator 31 is communicated with the liquid reservoir of the accumulator 7 via the communication pipe 32, the separated lubricating oil moves to the accumulator 7 side and is accumulated to the same level. As a result, an amount of lubricating oil corresponding to the difference in the oil circulation rate (OC%) can be stored in the accumulator 7 and the oil separator 31 and stored in the oil reservoir provided in the housing of the compressor 3. Can be prevented.

  Therefore, a sufficient amount of lubricating oil can be circulated in the refrigeration cycle 9 during the cooling operation for driving the mist lubricating type compressor 2 having a large oil circulation rate (OC%). 2 can be mist lubricated. Therefore, when any of the compressors 2 and 3 is operated, there is no shortage of refueling, and a plurality of compressors 2 and 3 having different lubrication methods can be normally operated while being properly lubricated. The same effects as the first embodiment are achieved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
The present embodiment is different from the first embodiment in the configuration of the accumulator 40. Since other points are the same as those in the first embodiment, description thereof will be omitted.
The accumulator 40 of the present embodiment is a container body that is formed by connecting two relatively thin cylindrical bodies 41 and 42 so as to communicate with each other at two upper and lower positions, and from the bottom of the two cylindrical bodies 41 and 42. The accumulator 40 is configured by inserting two insertion pipes 43 and 44 having oil return holes 45 and 46 therein to a predetermined height position. The oil return holes 45 and 46 are disposed at different height positions as in the first embodiment.

  Using the accumulator 40 having the above-described configuration, the compressor 2 adopting a mist lubrication method having a large oil circulation rate (OC%) is connected to the insertion tube 43 side, and the oil circulation rate (OC%) is small to the insertion tube 44 side. The effect similar to the said 1st Embodiment is show | played also by connecting the compressor 3 which employ | adopted the lubrication system. In addition, since the accumulator 40 can be configured to be thin by reducing the diameter of the main body, the accumulator 40 is installed on the front wall surface of the refrigerator using a narrow space between the refrigerator and the cabin in a refrigerated vehicle or the like. It becomes possible to do.

  The present invention is not limited to the invention according to the above-described embodiment, and can be appropriately modified without departing from the gist thereof. For example, in the above-described embodiment, as an example of the installation position of the accumulator, the space between the refrigerator and the cabin is taken as an example, but it is needless to say that the accumulator can be installed at other positions such as below the chassis. Further, each of the compressors 2 and 3 may use a compression mechanism of any configuration such as a reciprocating, a rotary, a scroll, and a screw.

It is a refrigerating cycle figure of the refrigerating device concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the accumulator used for the freezing apparatus shown in FIG. FIG. 2 is a refrigeration cycle diagram in a precooling or cold insulation operation state in which a compressor 3 is driven in the refrigeration apparatus shown in FIG. 1. FIG. 2 is a refrigeration cycle diagram when a transition is made from a state in which the compressor 3 is driven to a cooling operation state in which the compressor 2 is driven in the refrigeration apparatus shown in FIG. 1. It is a refrigerating cycle figure of the refrigerating device concerning a 2nd embodiment of the present invention. It is a longitudinal cross-sectional view of the accumulator concerning 3rd Embodiment of this invention.

Explanation of symbols

1 Refrigeration equipment 2 Compressor (open type compressor)
3 Compressor (electric compressor)
7, 40 Accumulator 8A, 8B Suction pipe 9 Refrigeration cycle 10, 11, 30 Refrigerant outflow pipe 14 Traveling engine 15 Electromagnetic clutch 16 Power cable 17, 18 U-shaped pipe 19, 20 Oil return hole 31 Oil separator 32 Communication pipe 43 , 44 Insertion tube 45, 46 Oil return hole O Lubricating oil

Claims (6)

An accumulator having a plurality of refrigerant outflow pipes provided with oil return holes is installed in the low-pressure gas piping of the refrigeration cycle, and a plurality of compression units are operated individually by the accumulator via the refrigerant outflow pipes. The compressors are connected in parallel, and the plurality of compressors are refrigeration apparatuses each having a different lubrication method,
The oil return holes provided in the plurality of refrigerant outflow pipes are disposed at different height positions corresponding to the plurality of compressors ,
The compressor adopting a lubrication method with a high oil circulation rate is connected to the refrigerant outlet pipe side where the oil return hole is provided at a low position, and adopts a lubrication method with a low oil circulation rate. A refrigerator is connected to the refrigerant outlet pipe side where the oil return hole is provided at a high position .   The plurality of refrigerant outflow pipes are constituted by U-shaped pipes, and the oil return holes provided in the vicinity of the lowermost portion of each U-shaped pipe are arranged at different height positions. The refrigeration apparatus described in 1.   The plurality of refrigerant outflow pipes are constituted by insertion pipes inserted into the accumulator from the bottom thereof, and the oil return holes provided in the middle of the respective insertion pipes are arranged at different height positions. The refrigeration apparatus according to claim 1. An accumulator having a plurality of refrigerant outflow pipes provided with oil return holes is installed in the low-pressure gas piping of the refrigeration cycle, and a plurality of compression units are operated individually by the accumulator via the refrigerant outflow pipes. The compressors are connected in parallel, and the plurality of compressors are refrigeration apparatuses each having a different lubrication method,
In the refrigerant outflow pipe to the compressor adopting a lubrication system having a low oil circulation rate in the plurality of compressors, an oil separator that separates the lubricating oil in the refrigerant is provided at the outlet of the refrigerant outflow pipe. A refrigeration apparatus provided in communication with a reservoir.   At least one of the plurality of compressors is a mist lubrication type compressor having a high oil circulation rate in which lubricating oil is circulated and lubricated together with the refrigerant, and the oil return hole is disposed at a high position. Oil circulation in which at least one other unit connected to the outflow pipe or the refrigerant outflow pipe provided with the oil separator includes an oil sump in the housing and forcibly lubricates the lubricating oil in the sump 5. The refrigeration apparatus according to claim 1, wherein the compressor is a forced lubrication type compressor having a low rate. The mist lubrication type compressor has a drive shaft that protrudes outside the housing, is an open type compressor that is driven by obtaining power from a traveling engine of a refrigerated vehicle, and the forced lubrication type compressor is: 6. The refrigeration apparatus according to claim 5, wherein the refrigeration apparatus includes an oil sump in the housing and is driven by an electric motor using electric power from a commercial power source as a drive source.

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