CN105972883B - Refrigerator unit - Google Patents

Abstract

A freezer unit (3) comprising: a machine chamber provided with a compressor (11); and a heat exchange chamber (30) in which an outdoor heat exchanger and a blower (31) are arranged, wherein the refrigerator unit (3) has an oil separator (20), and the oil separator (20) is arranged in a blowing path of the blower (30) in the heat exchange chamber (30) and is provided in a discharge portion of the compressor (11). Thus, the oil temperature in the oil separator (20) can be cooled by the air blown by the air blower (30).

Description

Refrigerator unit

Technical Field

The present invention relates to a refrigerator unit.

Background

Conventionally, a refrigeration apparatus has a refrigeration cycle including a compression unit, a gas cooler, a throttle unit, and the like. The refrigerant compressed by the compression unit radiates heat by the gas cooler, is reduced in pressure by the throttle unit, and is evaporated by the evaporator. By this evaporation of the refrigerant, the ambient air is cooled. In recent years, such refrigeration systems have been unable to use freon refrigerants due to natural environmental problems and the like. Therefore, a refrigerating apparatus using carbon dioxide as a natural refrigerant has been developed as an alternative to the freon refrigerant. Since carbon dioxide refrigerant has a large difference in high and low pressures and a low critical pressure, a technique is known in which the high-pressure side of a refrigerant cycle is brought into a supercritical state by compression (see, for example, japanese patent publication No. 7-18602).

In the heat pump apparatus constituting the water heater, a carbon dioxide refrigerant capable of obtaining an excellent heating action is used for the gas cooler. In this case, the following structure is also developed: the refrigerant flowing out of the gas cooler is expanded in 2 stages, and a gas-liquid separator is interposed between the expansion devices to inject gas into the compressor (see, for example, japanese patent application laid-open No. 2007-178042).

On the other hand, in an evaporator provided in a showcase or the like, for example, in a refrigeration apparatus that cools a storage using a heat absorption action, the temperature of a refrigerant at an outlet of a gas cooler increases due to a high external air temperature (heat source temperature on the gas cooler side) or the like. Under such conditions, the specific enthalpy at the evaporator inlet becomes large, and thus there is a problem that the freezing capacity is significantly reduced. Under such conditions, if the discharge pressure (high-pressure-side pressure) of the compression unit is increased in order to ensure the freezing capacity, the compression power increases, and the efficiency coefficient decreases.

In view of the above, a so-called split cycle (split cycle) refrigeration system has been proposed in which the refrigerant cooled by the gas cooler is split into two refrigerant flows, one of the split refrigerant flows is throttled by an auxiliary throttle unit, and then flows through one passage of a split heat exchanger, the other refrigerant flow flows through the other passage of the split heat exchanger to perform heat exchange, and then flows into the evaporator through a main throttle unit. According to such a refrigeration apparatus, the refrigeration capacity can be improved by reducing the specific enthalpy of the evaporator inlet by cooling one refrigerant flow after decompression and expansion and by reducing the specific enthalpy of the evaporator inlet (see, for example, japanese patent application laid-open No. 2011-133207).

However, in the above-described conventional technique, if the oil temperature in the oil separator becomes high, the viscosity of the oil decreases, and there is a problem that the sliding portion of the compressor may be worn.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a refrigerator unit capable of cooling oil temperature in an oil separator.

The refrigerator unit of the present invention includes: a machine chamber in which the compressor is disposed; and a heat exchange chamber in which the outdoor heat exchanger and the blower are disposed, wherein the refrigerator unit includes an oil separator disposed in a blowing path of the blower in the heat exchange chamber and provided in a discharge portion of the compressor.

According to the present invention, since the oil separator provided in the discharge portion of the compressor is disposed in the air blowing path of the air blower, it is possible to provide a refrigerator unit that cools the oil temperature in the oil separator by the air blowing of the air blower.

Drawings

Fig. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to an embodiment of the present invention.

Fig. 2 is a P-H diagram in an intermediate environment in which the outside air temperature is about +25 ℃, for example, in the embodiment of the present invention.

Fig. 3 is a P-H diagram in an environment (summer season, etc.) in which the outside air temperature is +30 ℃ or higher in the embodiment of the present invention, for example.

Fig. 4 is a P-H diagram in an environment (winter season, etc.) in which the outside air temperature is reduced to +20 ℃ or lower in the embodiment of the present invention, for example.

Fig. 5 is a perspective view showing a schematic configuration of a state in which a front cover of a freezer unit is removed according to the embodiment of the present invention.

Fig. 6 is a front view showing a schematic configuration of a state in which a front cover of a freezer unit is removed according to the embodiment of the present invention.

Fig. 7 is an exploded perspective view of a unit main body of a freezer unit according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a refrigerant circuit diagram of a refrigeration apparatus R according to an embodiment of the present invention.

The refrigeration apparatus R of the present embodiment includes: a refrigerator unit 3 installed in a machine room of a store such as a supermarket; and one or more showcases 4 (only one showcase is shown in the figure) provided in a shop of the shop. The refrigerating machine unit 3 and the showcase 4 are connected by a refrigerant pipe (liquid pipe) 8 through a unit outlet 6, and are connected by a refrigerant pipe 9 through a unit inlet 7, thereby constituting a predetermined refrigerant circuit 1.

The refrigerant circuit 1 uses carbon dioxide (R744) whose refrigerant pressure on the high-pressure side becomes equal to or higher than its critical pressure (supercritical) as the refrigerant. The carbon dioxide refrigerant is a natural refrigerant that is suitable for the global environment and takes into consideration flammability, toxicity, and the like. As the lubricating oil, for example, conventional oil selected from mineral oil (mineral oil), alkylbenzene oil, ether oil, ester oil, PAG (polyglycol lubricating oil), and the like can be used.

The refrigerator unit 3 includes a compressor 11 as a compression unit. In the present embodiment, the compressor 11 is an internal intermediate pressure type 2-stage compression type rotary compressor. The compressor 11 is constituted by: a closed container 12; and a rotary compression mechanism portion including an electric element 13 as a driving element disposed and housed in an upper portion of the internal space of the closed casing 12; a 1 st (low stage side) rotary compression element (1 st compression element) 14 and a 2 nd (high stage side) rotary compression element (2 nd compression element) 16 which are disposed below the electric element 13 and driven by the rotary shaft.

The 1 st rotary compression element 14 of the compressor 11 compresses the low-pressure refrigerant drawn into the compressor 11 from the low-pressure side of the refrigerant circuit 1 through the refrigerant pipe 9, boosts the pressure to an intermediate pressure, and discharges the compressed refrigerant. The 2 nd rotary compression element 16 further sucks and discharges the intermediate-pressure refrigerant compressed and discharged by the 1 st rotary compression element 14, compresses the refrigerant to increase the pressure to a high pressure, and discharges the refrigerant to the high-pressure side of the refrigerant circuit 1. The compressor 11 is a variable-frequency compressor, and is configured to be capable of controlling the rotation speed of the 1 st rotary compression element 14 and the 2 nd rotary compression element 16 by changing the operating frequency of the electric element 13.

A low-stage-side suction port 17 communicating with the 1 st rotary compression element 14, a low-stage-side discharge port 18 communicating with the inside of the closed casing 12, a high-stage-side suction port 19 communicating with the 2 nd rotary compression element 16, and a high-stage-side discharge port 21 are formed in a side surface of the closed casing 12 of the compressor 11. One end of a refrigerant introduction pipe 22 is connected to the low-stage-side suction port 17 of the compressor 11, and the other end of the refrigerant introduction pipe 22 is connected to the refrigerant pipe 9 at the unit inlet 7.

The gas refrigerant of low pressure (LP: about 2.6MPa in the normal operation state) drawn into the low-pressure portion of the 1 st rotary compression element 14 from the low-stage side suction port 17 is boosted to an intermediate pressure (MP: about 5.5MPa in the normal operation state) by the 1 st rotary compression element 14, and is discharged into the closed casing 12. Thereby, the inside of the closed casing 12 becomes an intermediate pressure (MP).

Further, one end of an intermediate-pressure discharge pipe 23 is connected to the low-stage discharge port 18 of the compressor 11 through which the intermediate-pressure gas refrigerant in the sealed container 12 is discharged, and the other end of the intermediate-pressure discharge pipe 23 is connected to an inlet of the intercooler 24. The intercooler 24 is used for air-cooling the intermediate-pressure refrigerant discharged from the 1 st rotary compression element 14, and one end of an intermediate-pressure suction pipe 26 is connected to an outlet of the intercooler 24, and the other end of the intermediate-pressure suction pipe 26 is connected to the high-stage suction port 19 of the compressor 11.

The gas refrigerant of the intermediate pressure (MP) sucked into the 2 nd rotary compression element 16 from the high-stage-side suction port 19 passes through the 2 nd rotary compression element 16 to be compressed in the 2 nd stage, and becomes a gas refrigerant of high temperature and high pressure (HP: about 9MPa supercritical pressure in a normal operation state).

One end of a high-pressure discharge pipe 27 is connected to a high-pressure-side discharge port 21 provided on the high-pressure chamber side of the 2 nd rotary compression element 16 of the compressor 11, and the other end of the high-pressure discharge pipe 27 is connected to an inlet of a gas cooler 28 serving as a radiator. Further, an oil separator 20 is provided in the middle of the high-pressure discharge pipe 27. The oil separator 20 separates oil from the refrigerant discharged from the compressor 11, and returns the separated oil to the sealed container 12 of the compressor 11 through the oil passage 25A and the electric valve 25B. In addition, the compressor 11 is provided with a float switch 55 that detects the oil level inside the compressor 11.

The gas cooler 28 cools the high-pressure discharge refrigerant discharged from the compressor 11, and a blower 31 (see fig. 5) for air-cooling the gas cooler 28 is disposed near the gas cooler 28.

One end of a gas cooler outlet pipe 32 is connected to an outlet of the gas cooler 28, and the other end of the gas cooler outlet pipe 32 is connected to an inlet of an electric expansion valve 33 serving as a pressure adjusting throttle portion. The electric expansion valve 33 throttles and expands the refrigerant flowing out of the gas cooler 28, and adjusts the high-pressure-side pressure of the refrigerant circuit 1 on the upstream side of the electric expansion valve 33. The outlet of the motor-operated expansion valve 33 is connected to the upper part of the tank 36 via a tank inlet pipe 34.

The tank 36 is a hollow body having a space with a predetermined volume inside. One end of a tank outlet pipe 37 is connected to a lower portion of the tank 36, and the other end of the tank outlet pipe 37 is connected to the refrigerant pipe 8 at the unit outlet 6.

On the other hand, showcases 4 installed in stores are connected to refrigerant pipes 8 and 9. The showcase 4 is provided with an electric expansion valve 39 as a main throttle portion, and an evaporator 41. The motor-operated expansion valve 39 and the evaporator 41 are sequentially connected between the refrigerant pipe 8 and the refrigerant pipe 9 (the motor-operated expansion valve 39 is connected to the refrigerant pipe 8 side, and the evaporator 41 is connected to the refrigerant pipe 9 side). A cold air circulation blower, not shown, for blowing air to the evaporator 41 is provided adjacent to the evaporator 41. As described above, the refrigerant pipe 9 is connected to the low-stage-side suction port 17 communicating with the 1 st rotary compression element 14 of the compressor 11 via the refrigerant introduction pipe 22.

On the other hand, one end of a gas pipe 42 is connected to an upper portion of the tank 36, and the other end of the gas pipe 42 is connected to an inlet of an electric expansion valve 43 as a throttle portion for the 1 st auxiliary circuit. The gas pipe 42 flows the gas refrigerant out of the upper portion of the tank 36 and flows into the motor expansion valve 43. One end of an intermediate pressure return pipe 44 is connected to an outlet of the motor-operated expansion valve 43, and the other end of the intermediate pressure return pipe 44 communicates with a middle portion of an intermediate pressure region connected to an intermediate pressure portion of the compressor 11, for example, the intermediate pressure suction pipe 26. The intermediate pressure return pipe 44 is inserted into the 1 st flow path 29A provided with the separate heat exchanger 29.

One end of a liquid pipe 46 is connected to a lower portion of the tank 36, and the other end of the liquid pipe 46 communicates with an intermediate pressure return pipe 44 on the downstream side of the motor-operated expansion valve 43. An electric expansion valve 47 as a throttle portion for the 2 nd auxiliary circuit is inserted into the liquid pipe 46. These motor-operated expansion valve 43 (the 1 st auxiliary circuit throttling part) and motor-operated expansion valve 47 (the 2 nd auxiliary circuit throttling part) constitute an auxiliary throttling part of the present application.

The liquid pipe 46 allows the liquid refrigerant to flow out of the lower portion of the tank 36 and into the motor-operated expansion valve 47. Further, the intermediate pressure return pipe 44, the motor-operated expansion valves 43, 47, the gas pipe 42 and the liquid pipe 46 located on the upstream side of the motor-operated expansion valves 43, 47, respectively, constitute an auxiliary circuit 48 of the present embodiment.

With this configuration, the electric expansion valve 33 is located on the downstream side of the gas cooler 28 and on the upstream side of the electric expansion valve 39. Further, the tank 36 is located on the downstream side of the motor-operated expansion valve 33 and on the upstream side of the motor-operated expansion valve 39. The split heat exchanger 29 is located on the downstream side of the tank 36 and on the upstream side of the motor-operated expansion valve 39. As described above, the refrigerant circuit 1 of the refrigeration apparatus R of the present embodiment is configured.

Various sensors are installed at various places of the refrigerant circuit 1. Specifically, a high-pressure sensor 49 is attached to the high-pressure discharge pipe 27. The high-pressure sensor 49 detects a high-pressure side pressure HP of the refrigerant circuit 1 (the pressure of the refrigerant discharged from the compressor 11 to the gas cooler 28, i.e., the pressure between the high-stage side discharge port 21 of the compressor 11 and the inlet of the motor-operated expansion valve 33). A low pressure sensor 51 is attached to the refrigerant introduction pipe 22. The low pressure sensor 51 detects a low pressure side pressure LP of the refrigerant circuit 1 (a pressure between the outlet of the motor-operated expansion valve 39 and the low-stage side suction port 17).

An intermediate pressure sensor 52 is attached to the intermediate pressure suction pipe 26. The intermediate pressure sensor 52 detects an intermediate pressure MP (a pressure in the intermediate pressure return pipe 44 between the high-stage side suction port 19 of the closed casing 12 and the outlets of the motor-operated expansion valves 43 and 47) which is a pressure in the intermediate pressure region of the refrigerant circuit 1.

A unit outlet sensor 53 is attached to the tank outlet pipe 37 on the downstream side of the split heat exchanger 29. Cell outlet sensor 53 detects pressure TP within canister 36. The pressure in the tank 36 is the pressure of the refrigerant that flows out of the refrigerating machine unit 3 and flows into the motor-operated expansion valve 39 from the refrigerant pipe 8. A discharge temperature sensor 61 is attached to the high-pressure discharge pipe 27 connected to the high-stage side discharge port 21 of the compressor 11. The discharge temperature sensor 61 detects the temperature (discharge temperature) of the refrigerant discharged from the compressor 11 to the gas cooler 28.

A unit outlet temperature sensor 54 is attached to the tank outlet pipe 37. A unit inlet temperature sensor 56 is attached to the refrigerant introduction pipe 22.

These sensors 49, 51, 52, 53, 54, 56, and 61 are connected to inputs of a control device 57 which is configured by a microcomputer and constitutes a control unit of the refrigerating machine unit 3. The float switch 55 is also connected to an input of the control device 57. Further, the electric element 13 of the compressor 11, the electric valve 25B, the blower 31, the electric expansion valve (the pressure adjusting throttle portion) 33, the electric expansion valve (the 1 st auxiliary circuit throttle portion) 43, the electric expansion valve (the 2 nd auxiliary circuit throttle portion) 47, and the electric expansion valve (the main throttle portion) 39 are connected to the output of the control device 57. The control device 57 controls these elements based on the output of each sensor, setting data, and the like.

In the following description, the electric expansion valve 39 (main throttle portion) on the showcase 4 side and the above-described cooling air circulation fan are also controlled by the control device 57. However, in actual cases, these are controlled by a main control device (not shown) of the store by a control device (not shown) on the showcase 4 side operating in cooperation with the control device 57. Therefore, the control unit in the present disclosure is a concept including at least any one of the control device 57, the control device on the showcase 4 side, the main control device, and the like.

(2) Operation of the refrigerating apparatus R

Based on the above configuration, the operation of the refrigeration apparatus R will be described next.

When the electric element 13 of the compressor 11 is driven by the control device 57, the 1 st rotary compression element 14 and the 2 nd rotary compression element 16 rotate, and a gas refrigerant (carbon dioxide) having a low pressure (the above-mentioned LP: about 2.6MPa in a normal operation state) is sucked into the low-pressure portion of the 1 st rotary compression element 14 from the low-stage side suction port 17. The gas refrigerant is further pressurized to an intermediate pressure (MP: about 5.5MPa in the normal operation state) by the 1 st rotary compression element 14, and discharged into the closed casing 12. Thereby, the inside of the closed casing 12 becomes an intermediate pressure (MP).

Further, the intermediate-pressure gas refrigerant in the closed casing 12 passes through the intermediate-pressure discharge pipe 23 from the low-stage side discharge port 18, enters the intercooler 24, is cooled in air therein, and then returns to the high-stage side suction port 19 through the intermediate-pressure suction pipe 26. The gas refrigerant of the intermediate pressure (MP) returned to the high-stage-side suction port 19 is sucked into the 2 nd rotary compression element 16, compressed in the 2 nd stage by the 2 nd rotary compression element 16, becomes a gas refrigerant of high temperature and high pressure (HP: about 9MPa of supercritical pressure in the above-described normal operation state), and is discharged from the high-stage-side discharge port 21 to the high-pressure discharge pipe 27.

The gas refrigerant discharged to the high-pressure discharge pipe 27 flows into the oil separator 20, and the oil contained in the refrigerant is separated. The separated oil passes through the oil passage 25A and the motor-operated valve 25B, and is returned to the closed casing 12. Further, the control device 57 controls the electric valve 25B to adjust the amount of oil returned to maintain the oil level in the closed casing 12, based on the oil level in the closed casing 12 detected by the float switch 55.

(2-1) control of the electric expansion valve 33

On the other hand, the gas refrigerant from which oil has been separated by the oil separator 20 flows into the gas cooler 28 and is cooled in the air, and then passes through the gas cooler outlet pipe 32 and reaches the motor-operated expansion valve (pressure-adjusting throttle section) 33. The electric expansion valve 33 is provided to control the high-pressure side pressure HP of the refrigerant circuit 1 on the upstream side of the electric expansion valve 33 to a predetermined target value THP (for example, 9MPa or the like as described above, and is set as described later). The valve opening degree of the motor-operated expansion valve 33 is controlled by the control device 57 based on the output of the high pressure sensor 49.

(2-1-1) setting of opening degree at startup of electric expansion valve 33

First, the controller 57 sets the opening degree (opening degree at startup) of the motor-driven expansion valve 33 at startup of the refrigeration apparatus R, based on the detected pressure (high-pressure-side pressure HP) of the high-pressure sensor 49, which is an index indicating the outside air temperature. Since there is a correlation between the high-pressure-side pressure HP detected by the high-pressure sensor 49 and the external atmospheric temperature, the control device 57 can determine the external atmospheric temperature from the high-pressure-side pressure HP. In the case of the present embodiment, the control device 57 is provided with a data table showing the relationship between the high-pressure-side pressure HP (external atmospheric temperature) at the time of startup and the valve opening degree at the time of startup of the motor-operated expansion valve 33 in advance. The controller 57 estimates the external atmospheric temperature at the time of startup, and sets the valve opening degree at the time of startup of the motor-driven expansion valve 33 based on the data table such that the valve opening degree increases as the high-pressure side pressure HP (external atmospheric temperature) increases, whereas the valve opening degree decreases as the high-pressure side pressure HP decreases (set in the data table).

This can suppress abnormal increase in the high-pressure-side pressure HP of the refrigerant circuit 1 on the upstream side of the motor-operated expansion valve 33 at the time of start-up of the compressor 11 (start-up of the refrigeration apparatus R) in an environment where the outside air temperature is high, thereby protecting the compressor 11.

The compressor 11 causes the high-side pressure HP to rise particularly at startup. Therefore, a protection function is provided to forcibly stop the compressor 11 at a high value (abnormal high pressure) equal to or higher than a predetermined value. However, by setting the valve opening degree at the time of starting the electric expansion valve 33 as described above, the forcible stop can be suppressed or prevented before the protective operation is performed.

In the present embodiment, the case where the external atmospheric temperature is estimated by the control device 57 based on the high-pressure-side pressure HP detected by the high-pressure sensor 49 is described, but the present invention is not limited to this configuration, and an external atmospheric temperature sensor may be separately provided to directly detect the external atmospheric temperature (hereinafter, in the description relating to the estimated temperature, a separate temperature sensor may be similarly disposed to detect the temperature).

(2-1-2) setting of target value THP of high-side pressure HP in operation

As described above, the control device 57 sets the target value THP based on the detected pressure (high-pressure-side pressure HP) of the high-pressure sensor 49, which is an index indicating the outside air temperature. In this case, the control device 57 sets the target value THP as follows: the target value THP is increased as the high-pressure-side pressure HP (external atmospheric temperature) is higher, whereas the target value THP is decreased as the external atmospheric temperature is lower. The standard value of the target value THP of the high-pressure side pressure HP in this case is 9MPa or the like. The controller 57 calculates an adjustment value (number of steps) of the valve opening degree of the electric expansion valve 33 based on the difference between the high-pressure-side pressure HP detected by the high-pressure sensor 49 and the target value THP, and adds the adjustment value to the valve opening degree at the time of starting to control the electric expansion valve 33. This enables control to bring the high-pressure side pressure HP closer to the target value THP.

In this case, the target value THP may be set using a preset data table or may be calculated by a calculation formula. However, when it is difficult to perform control, the external atmospheric temperature may be directly acquired by using the external atmospheric temperature sensor and the value may be used for setting, as described above.

Accordingly, in an environment where the outside air temperature is high, the target value THP during operation of the high-pressure-side pressure HP on the upstream side of the electric expansion valve 33 becomes high, and in an environment where the outside air temperature is low, the target value THP becomes low. That is, in a situation where the high-pressure-side pressure HP becomes high due to the influence of a high external atmospheric temperature, the target value THP becomes high, and therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 33 becomes excessively large and the pressure in the tank 36 becomes excessively high. Conversely, in a situation where the high-pressure side pressure HP decreases due to a low external atmospheric temperature, the target value THP also decreases, and therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 33 becomes excessively small and the amount of refrigerant flowing into the tank 36 decreases.

Further, by these processes, the valve opening degree of the electric expansion valve 33 can be appropriately controlled regardless of the change in the external atmospheric temperature caused by the season change, and both the securing of the refrigerating capacity of the refrigerating apparatus R and the protection of the compressor 11 can be appropriately achieved.

(2-1-3) control of the upper limit value MHP of the high-side pressure HP

In addition, when the high-pressure side pressure HP on the upstream side of the electric expansion valve 33 increases to a predetermined upper limit MHP (for example, 11MPa or the like) due to the influence of the installation environment or the load at the time of the above control, the control device 57 increases the valve opening degree of the electric expansion valve 33 by a predetermined number of steps. Since the high-pressure side pressure HP decreases due to the increase in the valve opening degree, the high-pressure side pressure HP can be maintained at the upper limit value MHP or less at all times. This can accurately suppress an abnormal increase in the high-pressure-side pressure HP on the upstream side of the motor-operated expansion valve 33, and can reliably protect the compressor 11, thereby avoiding the forced stop (protection operation) of the compressor 11 due to an abnormally high pressure.

The supercritical gas refrigerant flowing out of the gas cooler 28 is throttled and expanded by the electric expansion valve 33 to be liquefied, passes through the tank inlet pipe 34, flows into the tank 36 from above, and a part of the refrigerant is evaporated. The tank 36 temporarily stores and separates the refrigerant in a liquid state and a gas state flowing out from the electric expansion valve 33. The tank 36 also functions to absorb pressure changes in the high-pressure-side pressure of the refrigeration apparatus R (in this case, the region upstream of the tank 36 to the high-pressure discharge pipe 27 of the compressor 11) and fluctuations in the refrigerant circulation amount.

The liquid refrigerant accumulated in the lower portion of the tank 36 flows out of the tank outlet pipe 37 (main circuit 38), and is cooled (supercooled) in the 2 nd flow path 29B of the split heat exchanger 29 by the refrigerant flowing through the 1 st flow path 29A (sub circuit 48) as described later. The cooled refrigerant then flows out of the refrigerator unit 3, and flows into the electric expansion valve (main throttle) 39 through the refrigerant pipe 8.

The refrigerant flowing into the motor-operated expansion valve 39 is throttled and expanded at this point, and the liquid amount further increases, and flows into the evaporator 41 and evaporates. By the heat absorption effect, a cooling effect can be exerted. The control device 57 controls the valve opening degree of the electric expansion valve 39 based on the output of the temperature sensor that detects the temperature of each of the inlet side and the outlet side of the evaporator 41, and adjusts the degree of superheat of the refrigerant in the evaporator 41 to an appropriate value. The low-temperature gas refrigerant flowing out of the evaporator 41 returns to the refrigerating machine unit 3 from the refrigerant pipe 9, passes through the refrigerant introduction pipe 22, and is sucked into the low-stage side suction port 17 communicating with the 1 st rotary compression element 14 of the compressor 11. This is the flow of the refrigerant in the main circuit 38.

(2-2) control of the electric expansion valve 43

Next, the flow of the refrigerant in the auxiliary circuit 48 will be described. As described above, the electric expansion valve 43 (the 1 st auxiliary circuit throttling portion) is connected to the gas pipe 42 connected to the upper portion of the tank 36. The gas refrigerant flows out of the upper portion of the tank 36 through the motor-operated expansion valve 43 and flows into the 1 st flow path 29A of the split heat exchanger 29.

The gas refrigerant accumulated in the upper portion of the tank 36 is reduced in temperature by evaporation in the tank 36. The gas refrigerant in the upper portion of the tank 36 flows out from a gas pipe 42 connected to the upper portion of the tank 36 and constituting an auxiliary circuit 48, is compressed by the motor-operated expansion valve 43, and then flows into the 1 st flow path 29A of the split heat exchanger 29. The gas refrigerant cools the refrigerant flowing through the 2 nd flow path 29B, passes through the intermediate-pressure return pipe 44, joins the intermediate-pressure suction pipe 26, and is sucked into the intermediate-pressure portion of the compressor 11.

The electric expansion valve 43 functions to throttle the refrigerant flowing out of the upper portion of the tank 36, and also functions to adjust the pressure in the tank 36 (the pressure of the refrigerant flowing into the electric expansion valve 39) to a predetermined target value SP. The control device 57 controls the valve opening degree of the motor-operated expansion valve 43 based on the output of the unit outlet sensor 53. When the valve opening degree of the motor-operated expansion valve 43 is increased, the outflow amount of the gas refrigerant from the tank 36 is increased, and the pressure in the tank 36 is decreased.

In the present embodiment, the target value SP is set to be lower than the high-pressure-side pressure HP and higher than the intermediate pressure MP, for example, 6 MPa. The control device 57 calculates an adjustment value (number of steps) of the valve opening degree of the electric expansion valve 39 based on the difference between the pressure TIP (pressure of the refrigerant flowing into the electric expansion valve 39) in the tank 36 detected by the unit outlet sensor 53 and the target value SP. Further, the control device 57 adds the adjustment value to a valve opening degree at startup described later to control the pressure TIP (pressure of the refrigerant flowing into the electric expansion valve 39) in the tank 36 to be the target value SP. That is, when the pressure TIP in the tank 36 rises above the target value SP, the valve opening degree of the electric expansion valve 43 is increased to cause the gas refrigerant to flow out of the tank 36 to the gas pipe 42, whereas when the pressure TIP falls below the target value SP, the valve opening degree is controlled to be reduced and closed.

(2-2-1) setting of opening degree at startup of electric expansion valve 43

The controller 57 sets the valve opening degree (start-time opening degree) of the electric expansion valve 43 at the start-up time of the refrigeration apparatus R based on the detected pressure of the high-pressure sensor 49 (the high-pressure-side pressure HP or the external atmospheric temperature directly detected when the external atmospheric temperature sensor is provided as described above) as an index indicating the external atmospheric temperature. In the case of the present embodiment, as described above, the control device 57 is provided with a data table showing the relationship between the high-pressure-side pressure HP (external atmospheric temperature) at the time of startup and the valve opening degree at the time of startup of the motor-operated expansion valve 43 in advance.

The controller 57 estimates the external atmospheric temperature at the time of startup, and sets the valve opening degree at the time of startup of the motor-driven expansion valve 43 based on the data table such that the valve opening degree increases as the high-pressure side pressure HP (external atmospheric temperature) increases, and conversely, the valve opening degree decreases as the high-pressure side pressure HP decreases (set in the data table). This can suppress a rise in the pressure in the tank 36 at the time of startup in an environment where the outside air temperature is high, and can prevent a rise in the pressure of the refrigerant flowing into the motor-operated expansion valve 39.

In the present embodiment, as described above, the target value SP of the pressure TIP (the pressure of the refrigerant flowing into the electric expansion valve 39) in the tank 36 is controlled to be fixed at 6 MPa. However, the present disclosure is not limited to this example, and the target value SP may be set based on the detected pressure (high-pressure-side pressure HP) of the high-pressure sensor 49, which is an index indicating the outside atmospheric temperature, as in the case of the electric expansion valve 33. In this case, the target value SP is set such that the target value SP is increased as the high-pressure-side pressure HP (external atmospheric temperature) is higher, and conversely, the target value SP is decreased as the external atmospheric temperature is lower.

Therefore, in an environment where the outside air temperature is high, the pressure of the refrigerant flowing into the electric expansion valve 39 becomes high as the target value SP during operation, and in an environment where the outside air temperature is low, the target value SP becomes low. That is, in a situation where the pressure is high due to the influence of a high outside air temperature, the target value SP of the pressure of the refrigerant flowing into the electric expansion valve 39 is high, and therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 43 becomes excessively large and the refrigerant excessively flows into the auxiliary circuit 48. Conversely, in a situation where the pressure is low due to a low outside air temperature, the target value SP of the pressure of the refrigerant flowing into the electric expansion valve 39 is low, and therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 43 becomes too small and the amount of the refrigerant flowing into the auxiliary circuit 48 is excessively reduced. Accordingly, the valve opening degree of the electric expansion valve 43 can be appropriately controlled regardless of the change in the external atmospheric temperature caused by the change of seasons, and the amount of refrigerant flowing through the auxiliary circuit 48 can be accurately adjusted.

(2-2-2) control of predetermined value MTIP of tank internal pressure TIP

When the pressure TIP (pressure of the refrigerant flowing into the electric expansion valve 39) in the tank 36 is increased to a predetermined value MTIP (for example, 7 MPa) due to the influence of the installation environment or the load during the above control, the control device 57 increases the valve opening degree of the electric expansion valve 43 by a predetermined number of steps. Since the pressure TIP in the tank 36 is reduced by the increase in the valve opening degree, the pressure TIP can be maintained at the predetermined value MTIP or less at all times, and the effects of suppressing the influence of the pressure variation of the high-pressure side and suppressing the pressure of the refrigerant sent to the electric expansion valve 39 can be reliably achieved.

(2-3) control of the electric expansion valve 47

As described above, the electric expansion valve 47 (the 2 nd auxiliary circuit throttling portion) is connected to the liquid pipe 46 connected to the lower portion of the tank 36. The liquid refrigerant flows out from the lower portion of the tank 36 through the motor-operated expansion valve 47, joins the gas refrigerant from the gas pipe 42, and flows to the 1 st flow path 29A of the split heat exchanger 29.

That is, the liquid refrigerant accumulated in the lower portion of the tank 36 flows out from the liquid pipe 46 constituting the auxiliary circuit 48 connected to the lower portion, is compressed by the motor-operated expansion valve 47, and then flows into the 1 st flow path 29A of the split heat exchanger 29 to be evaporated. The heat absorption action at this time increases the supercooling of the refrigerant flowing through the 2 nd flow path 29B, and then the liquid refrigerant passes through the intermediate pressure return pipe 44 to join the intermediate pressure suction pipe 26 and is sucked into the intermediate pressure portion of the compressor 11.

In this way, the motor-operated expansion valve 47 throttles the liquid refrigerant flowing out of the lower portion of the tank 36, evaporates in the 1 st flow path 29A of the split heat exchanger 29, and supercools the refrigerant in the main circuit 38 flowing through the 2 nd flow path 29B. The control device 57 controls the valve opening degree of the motor-operated expansion valve 47 to adjust the amount of the liquid refrigerant flowing through the 1 st flow path 29A of the split heat exchanger 29.

If the amount of supercooling of the refrigerant in the main circuit 38 in the split heat exchanger 29 increases, the liquid phase ratio of the refrigerant sent to the electric expansion valve 39 increases. Therefore, the refrigerant in a full liquid state flows into the motor-operated expansion valve 39, and the temperature of the refrigerant sucked into the compressor 11 is also lowered. As a result, the discharge temperature of the refrigerant discharged from the compressor 11 to the gas cooler 28 also decreases.

Then, the control device 57 controls the valve opening degree of the motor-operated expansion valve 47 based on the temperature (discharge temperature) of the refrigerant discharged from the compressor 11 to the gas cooler 28, which is detected by the discharge temperature sensor 61. Thus, the amount of the liquid refrigerant flowing through the 1 st flow path 29A of the split heat exchanger 29 can be adjusted, and the discharge temperature of the refrigerant discharged from the compressor 11 to the gas cooler 28 can be controlled to a predetermined target value TDT. That is, the valve opening degree of the electric expansion valve 47 is increased when the actual discharge temperature is higher than the target value TDT, and the valve opening degree is decreased when the discharge temperature is lower than the target value TDT. This can maintain the discharge temperature of the refrigerant of the compressor 11 at the target value TDT, thereby protecting the compressor 11.

In this case, the control device 57 changes the target value TDT of the discharge temperature of the refrigerant of the compressor 11 based on the detected pressure (low-pressure-side pressure LP) of the low-pressure sensor 51, which is an index indicating the evaporation temperature of the refrigerant in the evaporator 41, such that the target value TDT is lower as the low-pressure-side pressure LP (evaporation temperature) is higher, and the target value TDT is higher as the low-pressure-side pressure LP is lower. For example, when the evaporation temperature is lower than-20 ℃, the target value TDT is changed to +70 ℃, and when the evaporation temperature is higher than-20 ℃, the target value TDT is changed to +100 ℃.

This ensures supercooling of the refrigerant in the main circuit 38 in the 2 nd flow path 29B of the split heat exchanger 29 particularly under a refrigeration condition (such as a refrigerated showcase) where the evaporation temperature of the evaporator 41 is high, and stably maintains the freezing capacity.

(2-4) actual operation of the refrigerating apparatus R according to the outside air temperature

Next, the actual operating state of the refrigeration apparatus R will be described for each external atmospheric temperature using the P-H diagrams of fig. 2 to 4.

(2-4-1) intermediate stage

Fig. 2 is a P-H diagram in an intermediate environment in which the outside air temperature is about +25 ℃, for example, in the embodiment of the present invention.

As described above, the controller 57 controls the valve opening degree of the electric expansion valve 33 to control the high-pressure side pressure HP on the upstream side of the electric expansion valve 33 to the target value THP. The control device 57 controls the valve opening degree of the electric expansion valve 43 to adjust the amount of the gas refrigerant flowing out of the gas pipe 42, and controls the pressure TIP inside the tank 36 (the pressure of the refrigerant flowing into the electric expansion valve 39) to a target value SP. Further, the control device 57 controls the valve opening degree of the electric expansion valve 47 to adjust the amount of the liquid refrigerant flowing out of the liquid pipe 46, thereby adjusting the discharge temperature of the refrigerant of the compressor 11 to the target value TDT.

The line descending at X1 to X2 in fig. 2 represents the pressure reduction of the electric expansion valve 33. The pressure of X2 (the pressure TIP in the tank 36) is adjusted to a target value SP by the electric expansion valve 43. At X2, at least one of liquid and gas is branched from the tank 36, and a line from X2 to the left shows supercooling of the liquid refrigerant in the main circuit 38 toward the electric expansion valve 39. Also at X3, the liquid refrigerant is throttled by electric expansion valve 39 so that the pressure drops (this is the same in fig. 3).

During the intermediate period, the intermediate pressure MP is reduced, so that a difference can be produced between it and the pressure TIP in the tank 36 adjusted by the electric expansion valve 43. Thus, the split heat exchanger 29 can secure the heat exchange amount necessary for supercooling the refrigerant in the main circuit 38, and therefore the refrigerant circuit 1 is a combined cycle of a 2-stage expansion cycle and a so-called split cycle.

(2-4-2) high outside atmospheric temperature (summer, etc.)

Fig. 3 is a P-H diagram in an environment (summer season, etc.) in which the outside air temperature is +30 ℃ or higher according to the embodiment of the present invention.

In the case where the outside atmospheric temperature is high, the intermediate pressure MP becomes higher than that in fig. 2, and the difference from the pressure TIP in the tank 36 disappears. Therefore, the amount of heat exchange in the separate heat exchanger 29 is reduced, and the refrigerant in the main circuit 38 cannot be supercooled. Further, since the high-pressure side pressure HP tends to increase, the valve opening degree of the motor-driven expansion valve 33 is made larger than the intermediate period (control by the control device 57) in order to suppress this.

This increases the amount of refrigerant flowing into tank 36. The controller 57 increases the valve opening degree of the electric expansion valve 43 in order to suppress an increase in the pressure TIP (pressure of the refrigerant flowing into the electric expansion valve 39) in the tank 36. Therefore, the amount of refrigerant returned to the intermediate pressure portion (intermediate pressure suction pipe 26) of the compressor 11 increases, and therefore the intermediate pressure MP rises. This reduces the supercooling effect of the refrigerant in the main circuit 38 in the split heat exchanger 29, and the refrigerant circuit 1 becomes a so-called 2-stage expansion cycle.

(2-4-3) at a time of low outside atmospheric temperature (winter, etc.)

Fig. 4 is a P-H diagram of the embodiment of the present invention in an environment where the outside air temperature is reduced to +20 ℃ or lower (winter season, etc.), for example.

When the outside air temperature is low, the high-side pressure HP becomes lower than that in fig. 2 and 3. Further, as described above, since the target value THP also decreases, the valve opening degree of the electric expansion valve 33 is brought into a state close to full opening. Therefore, the pressure TIP in the tank 36 becomes a pressure close to the high-pressure-side pressure HP, and the effect of the tank 36 is reduced. However, since the refrigerant flowing out of the gas cooler 28 is easily liquefied due to a low outside air temperature, almost all of the refrigerant flowing into the tank 36 through the electric expansion valve 33 is liquefied, and a large amount of liquid refrigerant is stored in the tank 36.

Therefore, in the motor-operated expansion valves 43, 47, the liquid refrigerant is throttled and evaporated in the 1 st flow path 29A of the split heat exchanger 29. Therefore, the effect of the split heat exchanger 29 is increased, the refrigerant in the main circuit 38 (2 nd flow path 29B) can be surely supercooled, and the refrigerant circuit 1 is a split cycle.

As described above in detail, the refrigerator unit 3 of the present disclosure includes: an electric expansion valve 33 connected to the refrigerant circuit 1 on the downstream side of the gas cooler 28 and on the upstream side of the electric expansion valve 39; and a tank 36 connected to the refrigerant circuit 1 on the downstream side of the electric expansion valve 33 and on the upstream side of the electric expansion valve 39. The refrigerator unit 3 further includes: a split heat exchanger 29 provided in the refrigerant circuit 1 on the downstream side of the tank 36 and on the upstream side of the electric expansion valve 39; and an auxiliary circuit 48 for allowing the refrigerant in the tank 36 to flow through the motor-operated expansion valve 43 and the motor-operated expansion valve 47 to the 1 st flow path 29A of the split heat exchanger 29 and then to be sucked into the intermediate pressure portion of the compressor 11. The refrigerating machine unit 3 further includes a main circuit 38, and the main circuit 38 causes the refrigerant to flow out from the lower portion of the tank 36, to flow into the 2 nd flow path 29B of the split heat exchanger 29, to exchange heat with the refrigerant flowing through the 1 st flow path 29A, and to flow into the electric expansion valve 39.

Thus, the refrigerant flowing through the 1 st passage 29A of the split heat exchanger 29 constituting the auxiliary circuit 48 is expanded by the motor-operated expansion valves 43 and 47, and the refrigerant flowing through the 2 nd passage 29B of the split heat exchanger 29 constituting the main circuit 38 can be supercooled. This reduces the specific enthalpy at the inlet of the evaporator 41, and effectively improves the refrigerating capacity.

The refrigerant flowing through the 1 st passage 29A of the split heat exchanger 29 returns to the intermediate pressure portion of the compressor 11. Therefore, the amount of refrigerant sucked into the low-pressure portion of the compressor 11 is reduced, and the amount of compression work in the compressor 11 for compression from low pressure to intermediate pressure is reduced. As a result, the compression power of the compressor 11 is reduced, and the efficiency coefficient is improved.

Further, the refrigerant is expanded by the electric expansion valve 33, so that a part of the liquefied refrigerant is evaporated in the tank 36 to become a gas refrigerant having a reduced temperature, and the remaining part becomes a liquid refrigerant and is temporarily stored in a lower portion in the tank 36. The liquid refrigerant in the lower portion of the tank 36 passes through the 2 nd flow path 29B of the split heat exchanger 29 constituting the main circuit 38, and flows into the motor-operated expansion valve 39. This allows the refrigerant to flow into the motor-operated expansion valve 39 in a liquid-full state, and in particular, improves the freezing capacity of the evaporator 41 under cold storage conditions in which the evaporation temperature is high. Further, since the tank 36 also has an effect of absorbing variation in the amount of circulating refrigerant in the refrigerant circuit 1, an error in the amount of refrigerant charge is also absorbed.

The controller 57 is configured to control the electric expansion valve 33, and to adjust the high-pressure side pressure HP of the refrigerant circuit 1 on the upstream side of the electric expansion valve 33 by the electric expansion valve 33. This can avoid problems such as an increase in the high-pressure-side pressure HP at which the refrigerant is discharged from the compressor 11, a decrease in the operating efficiency of the compressor 11, and damage to the compressor 11.

In this case, controller 57 sets the opening degree at the time of starting electric expansion valve 33 based on the index indicating the outside air temperature such that the opening degree is increased as the outside air temperature is higher. This can suppress an increase in the high-pressure-side pressure HP at the time of startup in an environment where the outside air temperature is high, thereby protecting the compressor 11.

The control device 57 controls the valve opening degree of the electric expansion valve 33 so as to control the high-pressure side pressure HP of the refrigerant circuit 1 on the upstream side of the electric expansion valve 33 to a predetermined target value THP, and sets the target value THP of the high-pressure side pressure HP based on an index indicating the outside air temperature such that the higher the outside air temperature, the higher the target value THP. Accordingly, in an environment where the outside air temperature is high, the high-pressure side pressure HP on the upstream side of the electric expansion valve 33 becomes high as the target value THP during operation, whereas in an environment where the outside air temperature is low, the target value THP becomes low.

Accordingly, in a situation where the high-pressure-side pressure HP becomes high due to the influence of a high external atmospheric temperature, the target value THP becomes high, and therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 33 becomes excessively large and the pressure in the tank 36 becomes excessively high. Conversely, in a situation where the high-pressure side pressure HP decreases due to a low external atmospheric temperature, the target value THP also decreases, and therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 33 becomes excessively small and the amount of refrigerant flowing into the tank 36 decreases.

Accordingly, regardless of the change in the external atmospheric temperature caused by the change of seasons, the opening degree of the electric expansion valve 33 can be appropriately controlled, and both the securing of the refrigeration capacity and the protection of the compressor 11 can be appropriately achieved.

Further, when the high-pressure side pressure HP of the refrigerant circuit 1 on the upstream side of the motor-operated expansion valve 33 rises to the predetermined upper limit MHP, the control device 57 can always maintain the high-pressure side pressure HP at the upper limit MHP or less because the valve opening degree of the motor-operated expansion valve 33 is increased. This makes it possible to accurately suppress an abnormal increase in the high-pressure-side pressure HP on the upstream side of the motor-operated expansion valve 33, to reliably protect the compressor 11, and to avoid a stop (protection operation) of the compressor 11 due to an abnormally high pressure.

The refrigerating machine unit includes an electric expansion valve 43, and the auxiliary circuit 48 includes a gas pipe 42 through which the refrigerant flows out from the upper portion of the tank 36 and flows into the electric expansion valve 43. Further, the controller 57 is configured to adjust the pressure TIP of the refrigerant flowing into the electric expansion valve 39 by the electric expansion valve 43. Thus, the electric expansion valve 43 can control the pressure TIP of the refrigerant sent to the electric expansion valve 39 by suppressing the influence of the fluctuation of the high-pressure-side pressure HP.

Further, the electric expansion valve 43 reduces the pressure TIP of the refrigerant flowing into the electric expansion valve 39, and a pipe having a low pressure resistance can be used as the pipe reaching the electric expansion valve 39. This improves workability and construction cost.

Further, the low-temperature gas is pumped out from the upper portion of the tank 36 through the electric expansion valve 43, and the pressure in the tank 36 is lowered. This reduces the temperature in the tank 36, and therefore, a condensation action of the refrigerant occurs, and the refrigerant in a liquid state can be efficiently stored in the tank 36.

In this case, the controller 57 sets the valve opening degree in a direction in which the valve opening degree at the time of starting the electric expansion valve 43 is increased as the outside air temperature increases, based on the index indicating the outside air temperature. This can suppress a rise in the pressure in the tank 36 at the time of startup in an environment where the outside air temperature is high, and can prevent a rise in the pressure of the refrigerant flowing into the motor-operated expansion valve 39.

The control device 57 may be configured to control the valve opening degree of the electric expansion valve 43 so that the pressure TIP of the refrigerant flowing into the electric expansion valve 39 is controlled to a predetermined target value SP, and to set the target value SP of the pressure of the refrigerant flowing into the electric expansion valve 39 based on an index indicating the outside air temperature so that the target value SP becomes higher as the outside air temperature becomes higher. Accordingly, in an environment where the outside air temperature is high, the pressure TIP of the refrigerant flowing into the electric expansion valve 39 becomes high as the target value SP during operation, while in an environment where the outside air temperature is low, the target value SP becomes low.

Thus, in a situation where the pressure becomes high due to the influence of a high external atmospheric temperature, the target value SP of the pressure TIP of the refrigerant flowing into the electric expansion valve 39 becomes high. Therefore, it is possible to prevent a problem that the valve opening degree of the motor-operated expansion valve 43 becomes excessively large and the refrigerant excessively flows into the auxiliary circuit 48. Conversely, in a situation where the pressure is low due to a low outside air temperature, the target value SP of the pressure TIP of the refrigerant flowing into the electric expansion valve 39 also becomes low. Therefore, it is possible to prevent a problem that the valve opening degree of the electric expansion valve 43 becomes excessively small and the amount of refrigerant flowing into the auxiliary circuit 48 is excessively reduced. Accordingly, the valve opening degree of the electric expansion valve 43 can be appropriately controlled regardless of the change in the external atmospheric temperature caused by the change of seasons, and the amount of refrigerant flowing through the auxiliary circuit 48 can be accurately adjusted.

Further, when the pressure of the refrigerant flowing into the motor-operated expansion valve 39 increases to a predetermined value MTIP, the control device 57 increases the valve opening degree of the motor-operated expansion valve 43. This can constantly maintain the pressure TIP of the refrigerant sent to the electric expansion valve 39 at or below the predetermined value MTIP, and can reliably achieve the effect of suppressing the influence of the high-pressure-side pressure fluctuation and the effect of suppressing the pressure of the refrigerant sent to the electric expansion valve 39.

The freezer unit is provided with an electric expansion valve 47, and the auxiliary circuit 48 has a liquid pipe 46 through which the refrigerant flows out of the lower portion of the tank 36 and into the electric expansion valve 47. The controller 57 controls the valve opening degree of the motor-operated expansion valve 47 to adjust the amount of the liquid refrigerant flowing through the 1 st flow path 29A of the split heat exchanger 29. Thereby, the discharge temperature of the refrigerant discharged from the compressor 11 to the gas cooler 28 is controlled to a predetermined target value TDT. Thus, the electric expansion valve 47 can cause the liquid refrigerant in the lower portion of the tank 36 to flow through the 1 st passage 29A of the split heat exchanger 29, thereby increasing the supercooling of the refrigerant in the main circuit 38 flowing through the 2 nd passage 29B of the split heat exchanger 29.

Thus, by increasing the liquid phase ratio of the refrigerant sent to the electric expansion valve 39, the refrigerant can be caused to flow into the electric expansion valve 39 in a full liquid state. Further, since the temperature of the refrigerant sucked into the compressor 11 is also lowered, the discharge temperature of the refrigerant discharged from the compressor 11 to the gas cooler 28 can be also lowered to the target value TDT as a result, and the compressor 11 can be reliably protected.

In this case, the control device 57 changes the target value TDT of the discharge temperature of the refrigerant such that the higher the evaporation temperature, the lower the target value TDT, based on the index indicating the evaporation temperature of the refrigerant in the evaporator 41. This ensures supercooling of the refrigerant in the main circuit 38 in the separate heat exchanger 29, particularly under cold storage conditions where the evaporation temperature of the evaporator 41 is high, and stably maintains the freezing capacity.

Next, a specific configuration of the refrigerating machine unit 3 in the refrigeration cycle shown in fig. 1 will be further described with reference to fig. 5 to 7.

Fig. 5 is a perspective view showing a schematic configuration of the refrigerator unit 3 according to the embodiment of the present invention with the front cover removed. Fig. 6 is a front view showing a schematic configuration of a state in which a front cover of the freezer unit 3 is removed. Fig. 7 is an exploded perspective view of the unit main body 100 of the freezer unit 3.

In the following description, the upper, lower, front, rear, and left and right indicate the upper, lower, front, rear, and left and right in the case where the freezer unit 3 is viewed from the front (as viewed from the front in fig. 6).

As shown in fig. 5 and 6, the freezer unit 3 includes a unit main body 100 and a front cover (not shown) attached to the front surface of the unit main body 100. The unit main body 100 includes a heat exchange chamber 30 in the right-hand chamber, a machine chamber 40 provided in a lower half of the left-hand chamber, and an electrical chamber 60 provided in an upper half of the left-hand chamber. The refrigerator unit 3 of the present embodiment is a so-called side-flow type refrigerator unit 3.

In the unit main body 100, an intercooler 24 and a gas cooler 28, which are outdoor heat exchangers having a substantially L-shape in plan view, are arranged along the rear surface from the right side surface of the unit main body 100. The intercooler 24 and the gas cooler 28 are provided in an overlapping manner (see fig. 7).

The intercooler 24 and the gas cooler 28 provided on the right side surface of the unit main body 100 are provided to have substantially the same length (including the same length) in the front-rear direction of the unit main body 100. The intercooler 24 and the gas cooler 28 provided on the rear surface of the unit main body 100 are provided to have a width of approximately 4-3 (including 4-3) from the right side when viewed from the front in the right direction from the unit main body 100.

A rear cover 72 (see fig. 7) having a substantially L shape (including an L shape) in a plan view (a top view) is provided at a left rear portion of the unit main body 100. The right end portion of the rear cover 72 is fixed to the left end portions of the intercooler 24 and the gas cooler 28. The front end of the rear cover 72 is fixed to the electric component chamber 60.

A corner cover 77 is provided on the outer sides of the intercooler 24 and the gas cooler 28 at the corner portion of the rear right of the unit main body 100.

The refrigerator unit 3 is provided with a partition plate 70 that divides the interior of the refrigerator unit into 2 parts in the vertical direction as a whole at a substantially central portion (including the central portion) of the interior. The partition plate 70 is bent obliquely leftward to the rear in a plan view, and the rear end portion of the partition plate 70 is fixed to the left end portions of the intercooler 24 and the gas cooler 28. A shelf 71 for constituting the electrical component chamber 60 is attached to the partition plate 70 in the upper half of the left-hand chamber.

With this configuration, the heat exchange chamber 30 as the right-side chamber, the machine chamber 40 as the lower half chamber of the left-side chamber, and the electrical chamber 60 as the upper half chamber of the left-side chamber are formed inside the freezer unit 3.

The heat exchange chamber 30 is provided with an oil separator 20 and a blower 31. As shown in fig. 7, the blower 31 is constituted by: a support 136 having an コ -shaped (U-shaped) shape when viewed from the side; fan motors 132 provided at 2 positions above and below the support 136; rotary shafts 133 provided to the fan motors 132, respectively; and fan bodies 134 respectively mounted on the rotation shafts 133.

As shown in fig. 5, the blower 31 is disposed at the center in the width direction of the heat exchange chamber 30 and at the front side (near side) in the front-rear direction, with the fan body 134 facing forward. The upper surface of the support 136 and the upper surface of the intercooler 24 are fixed by the support plate 35, and the blower 31 is fixed.

The oil separator 20 is provided deep on the left side of the heat exchange chamber 30, i.e., in a position close to the partition plate 70 and close to the gas cooler 28. The oil separator 20 is located on the front side of the gas cooler 28 and is disposed on the rear side of the fan body 134. The oil separator 20 is disposed at a position close to the partition plate 70 so as to be disposed in the machine chamber 40, without disposing the refrigerant pipe connected to the oil separator 20 in the heat exchange chamber 30 as much as possible.

A refrigerant pipe extending to the machine chamber 40 through a connection hole 78 provided at a lower portion of the partition plate 70 is connected to an upper portion of the oil separator 20.

The machine chamber 40 is provided with the compressor 11, the tank 36, and a refrigerant pipe connecting these components. The machine chamber 40 is provided with a partition wall 73 that divides the machine chamber 40 into left and right. An air passage S1 for cooling air is formed on the outer side (left side facing) of partition wall 73.

Air passage S1 is surrounded by partition wall 73 and support plate 74 that partitions the lower half of machine chamber 40 in the front and rear direction. The support plate 74 has a height of approximately half (including half) of the partition wall 73, and the front and rear of the machine chamber 40 are not partitioned above the support plate 74, and the space is widened in the front and rear direction of the machine chamber 40. Air passage S1 includes unit outlet 6 fixed to support plate 74 and unit inlet 7 fixed to partition wall 73. The bottom plate of the unit main body 100 is positioned below the air passage S1, and the bottom plate is provided with the vent hole 76.

Inside partition wall 73 (right side facing thereto) is provided a machine element space S2 surrounded by the bottom plate of electric equipment room 60, partition wall 73, and partition plate 70. The compressor 11, refrigerant piping, and the like are disposed in the machine element space S2. The refrigerant pipes are arranged densely in the width range between the partition wall 73 and the compressor 11 over the entire longitudinal direction of the machine chamber 40.

Tank space S3 is provided behind air passage S1, i.e., behind support plate 74, and tank 36 is provided in tank space S3. The tank space S3 and the air passage S1 are partitioned by the support plate 74, and the portion above the support plate 74 is not partitioned, and therefore they are connected.

An electrical chamber 60 including an electronic circuit board and the like is provided above the machine chamber 40. A slot 75 is provided in the side wall of the electrical component chamber 60 on the heat exchange chamber 30 side. The slot 75 communicates with a slot provided in the partition plate 70, and the electrical component chamber 60 and the machine chamber 40 communicate with each other through the slot.

In the present embodiment, first, the compressor 11 is operated, and thereby the refrigerant sent from the showcase 4 is sucked from the lower-stage-side suction port 17 of the compressor 11. The refrigerant is compressed to an intermediate pressure by the 1 st rotary compression element 14, and is discharged from the lower stage side discharge port 18. The refrigerant discharged from the low-stage-side discharge port 18 of the compressor 11 flows into the intercooler 24 through the intermediate-pressure discharge pipe 23, is cooled in the intercooler 24 by heat exchange with the outside air by the blower 31, and is returned to the high-stage-side suction port 19 of the compressor 11.

The refrigerant returned from the intercooler 24 is compressed to a desired pressure by the 2 nd rotary compression element 16 of the compressor 11, discharged from the high-stage side discharge port 21, passed through the oil separator 20, and sent to the gas cooler 28. The refrigerant sent from the compressor 11 is cooled in the gas cooler 28 by heat exchange with the outside atmosphere by the blower 31, and is sent to the tank 36 as a high-pressure refrigerant.

The refrigerant decompressed and cooled in the tank 36 is sent to a refrigeration load (evaporator 41) such as the showcase 4 through the unit outlet 6, and exchanges heat with the inside air in the evaporator 41 to cool the inside of the refrigerator. The refrigerant heat-exchanged in the evaporator 41 is returned to the compressor 11 through the unit inlet 7 and the refrigerant introduction pipe 22.

In the refrigerator unit 3, the outside air sucked by the blower 31 passes through the intercooler 24 and the gas cooler 28, and is discharged through the front unit (not shown) by the heat exchange chamber 30. At this time, the external air sucked by the blower 31 contacts the oil separator 20 disposed in the heat exchange chamber 30, and the oil stored in the oil separator 20 is cooled.

By disposing the oil separator 20 in the heat exchange chamber 30 in this way, the oil temperature can be lowered by approximately 5 ℃ (including 5 ℃) compared to the case where the oil separator 20 is disposed in the machine chamber 40.

As described above, according to the present embodiment, the oil separator 20 provided in the discharge portion of the compressor 11 is disposed in the air blowing path of the air blower 31, and therefore the oil separator 20 can be cooled by the air blowing of the air blower 31.

Further, according to the present embodiment, the intercooler 24 and the gas cooler 28 are provided open on the rear surface of the unit main body 100, and the blower 31 is disposed on the front side in the front-rear direction of the unit main body 100.

According to this configuration, since the air blowing path of the air blower 31 is formed from the back to the front of the unit main body 100, the oil in the oil separator 20 can be efficiently cooled by the air blowing of the air blower 31. Further, since the blower 31 is disposed on the front side in the front-rear direction of the unit main body 100, a space that does not contact the fan body 134 can be secured even if the oil separator 20 is disposed in the heat exchange chamber 30.

In the present embodiment, the oil separator 20 is disposed adjacent to the partition plate 70.

According to this configuration, since the oil separator 20 is disposed in the vicinity of the partition plate 70, the length of the refrigerant pipe extending in the heat exchange chamber 30 can be shortened.

As described above, the refrigerator unit according to the 1 st aspect of the present disclosure includes: a machine chamber provided with a compressor; and a heat exchange chamber provided with an outdoor heat exchanger and a blower, wherein the refrigerator unit is provided with an oil separator which is arranged in a blowing path of the blower in the heat exchange chamber and is arranged at a discharge part of the compressor.

According to this configuration, the refrigerator unit can cool the oil temperature in the oil separator by the air blown by the blower.

In addition, the 2 nd aspect is based on the 1 st aspect, and the freezer unit further includes a unit main body, and a partition plate that partitions the inside of the unit main body into left and right sides when viewed from the front. The machine chamber is disposed on either the left or right side of the unit main body partitioned by the partition plate, and the heat exchange chamber is disposed on the other of the left or right side partitioned by the partition plate. Further, the outdoor heat exchanger is disposed open on at least the back side of the unit body, and the blower is disposed on the front side of the unit body.

With this configuration, the air blowing path of the air blower is formed from the rear surface to the front surface of the unit main body, and therefore the oil in the oil separator can be cooled with good air blowing efficiency by the air blower. Further, since the blower is disposed on the front side (forward of the center), even if the oil separator is disposed in the heat exchange chamber, a space that does not contact the blower can be secured.

In addition, according to the 3 rd aspect, the oil separator is disposed adjacent to the partition plate according to the 2 nd aspect.

According to this configuration, since the oil separator is disposed in the vicinity of the partition plate, the refrigerant pipe existing in the heat exchange chamber can be shortened.

In addition, according to the 4 th aspect, the refrigerator unit further includes a refrigeration cycle based on the 1 st to 3 rd aspects, and a carbon dioxide refrigerant is used as a refrigerant of the refrigeration cycle.

Thus, a refrigerating machine unit using a natural refrigerant that is suitable for the global environment and takes into consideration flammability, toxicity, and the like can be realized.

The present invention has been described above based on the embodiments of the present invention, but the present invention is not limited to the embodiments. The above description is merely an example of one embodiment of the present invention, and thus, any modification and application can be made without departing from the scope of the present invention.

As described above, according to the present invention, a special effect of providing a refrigerating machine unit capable of cooling the oil temperature in the oil separator by the blast air of the blower can be obtained. Therefore, the present invention is useful as a refrigerator unit or the like.

Claims (1)

1. A freezer unit comprising: a machine chamber provided with a compressor; and a heat exchange chamber provided with an outdoor heat exchanger and a blower, wherein,

the outdoor heat exchanger is disposed along a rear surface of the heat exchange chamber from a side surface thereof,

the outdoor heat exchanger extends to the rear of the machine room when viewed from the front,

a partition plate that partitions the machine chamber and the heat exchange chamber in a vertical direction is provided in a central portion of a unit main body of the freezer unit,

an oil separator is disposed between the outdoor heat exchanger and the blower at a position overlapping the blower and adjacent to the partition plate when viewed from the front, the oil separator being disposed in a discharge portion of the compressor,

the partition plate is bent obliquely to the rear in the direction away from the oil separator in a plan view,

the rear end of the partition plate is fixed to the end of the outdoor heat exchanger,

the blower is disposed on the front side of the unit main body,

carbon dioxide refrigerant is used as the refrigerant of the refrigeration cycle.

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