Refrigerating device and control method

Abstract

To provide a refrigerating device.SOLUTION: A refrigerating device (100) includes a compressor (1), an oil separator (2) for separating a refrigerant and an oil from the compressor (1), a condenser (3a) for condensing the refrigerant separated by the oil separator (2), an oil cooler (7) for cooling the oil separated by the oil separator (2), an air blower (9a) for blowing air to the condenser (3a) and the oil cooler (7), and an air blower control unit (17) for controlling the air volume of the air blower (9a). The condenser (3a) and the oil cooler (7) are integrated into one air heat exchanger (20a). The air blower control unit (17) adjusts the degree of cooling caused by the oil cooler (7) by controlling the air volume of the air blower (9a) on the basis of an index value related to the condenser (3a).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a refrigeration apparatus including a condenser and an oil cooler, and a method for controlling the refrigeration apparatus. [Background technology]

[0002] There is a demand to change the refrigerants used in refrigeration equipment to ones with a low global warming potential. Such a change in refrigerant is expected to result in a decline in the performance of the refrigeration equipment due to the effects of the refrigerant's physical properties. When considering replacing existing refrigeration equipment, it is desirable for the new refrigeration equipment to have performance as close as possible to that of the existing equipment. Therefore, there is a demand for improving performance while minimizing the need for additional components (for example, speed increase using an inverter).

[0003] Conventionally, refrigeration oil in a refrigeration system has been cooled using the refrigerant in the refrigeration cycle, but using the refrigerant in the refrigeration cycle to cool the refrigeration oil results in a corresponding loss of refrigeration capacity of the refrigeration system.

[0004] In relation to oil cooling, International Publication No. 2016 / 170680 (Patent Document 1) and Japanese Patent Laid-Open No. 2011-89736 (Patent Document 2) are known.

[0005] Patent Document 1 discloses a refrigeration and air conditioning system including an oil separator disposed on the discharge side of the compressor and on the inlet side of the condenser, a hot gas bypass pipe that directs refrigerant flowing from the oil separator to an evaporator, a hot gas control valve disposed on the hot gas bypass pipe, an oil return pipe that returns lubricating oil stored in the oil separator to the compressor, an oil cooler disposed on the oil return pipe that cools refrigeration oil flowing through the oil return pipe, an oil supply bypass circuit that branches off from the oil return pipe upstream of the oil cooler and merges with the oil return pipe downstream of the oil cooler, and an oil supply bypass motor-operated valve disposed on the oil supply bypass circuit. Patent Document 1 does not specify the specific location of the oil cooler, but the oil cooler is depicted as being independently attached to the condenser.

[0006] Patent Document 2 discloses an air conditioner having a structure in which refrigeration oil contained in refrigerant gas discharged from a compressor is separated by an oil separator provided on the compressor discharge side and returned to the compressor suction side, in which the refrigeration oil separated in the oil separator is introduced into a part of an outdoor heat exchanger, cooled by outside air, and returned to the compressor suction side, and a heat exchanger used to cool the refrigeration oil is located below the suction side of the refrigerant heat exchanger. Patent Document 2 also discloses that because the refrigerant condenser is located above and the heat exchanger (oil cooler section) used to cool the refrigeration oil is located below, the temperature of the lower part of the heat exchanger acting as a refrigerant evaporator can be increased during heating, preventing water from freezing in the water receiving section below the heat exchanger during defrosting and allowing drain water to be smoothly discharged, improving the reliability of the air conditioner.

[0007] The prior arts of Patent Documents 1 and 2 use an air heat exchanger in the oil cooling circuit and adjust the oil temperature by providing a bypass circuit that does not pass through the oil cooler. However, the prior art of Patent Document 1 aims to shorten the defrosting time using hot gas and is a technology aimed at increasing the hot gas temperature. The opening of the hot gas circuit triggers the opening of the oil bypass circuit to increase the hot gas temperature, thereby adjusting the flow rate. However, the use of an air heat exchanger still leaves the possibility of excessive drops in oil temperature due to low outdoor air temperatures, including during startup. In the prior art of Patent Document 2, the control of the oil bypass amount is performed to prevent a decrease in efficiency during heating. Therefore, the use of an air heat exchanger still leaves the possibility of excessive drops in oil temperature due to low outdoor air temperatures, including during startup. During heating, the air volume of the air heat exchanger's blower tends to be increased to ensure heating capacity, making excessive drops in oil temperature more likely. Furthermore, even during low outdoor air temperatures, there may be a heat load and cooling operation may be required. In this case, the oil bypass circuit is not used, so there is a risk of an excessive drop in oil temperature due to low outside air temperature. The excessive drop in oil temperature described above can cause a reduction in oil supply to the compressor due to an increase in oil viscosity, or can cause the temperature inside the compressor to cool excessively, which can lead to compressor failure. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2016 / 170680 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-89736 Summary of the Invention [Problem to be solved by the invention]

[0009] The present disclosure has been made in consideration of the above-mentioned drawbacks in the conventional technology, and aims to provide a refrigeration device that is compact and has reduced costs, while enabling smooth adjustment of oil temperature with a simple configuration. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the present disclosure provides a refrigeration system having the following features. The refrigeration system includes a compressor, an oil separator that separates refrigerant and oil from the compressor, a condenser that condenses the refrigerant separated by the oil separator, an oil cooler that cools the oil separated by the oil separator, a blower that sends air to the condenser and the oil cooler, and a blower control unit that controls the air volume of the blower. The condenser and oil cooler are integrated into a single air heat exchanger. The blower control unit adjusts the degree of cooling by the oil cooler by controlling the air volume of the blower based on an index value related to the condenser. [Effects of the Invention]

[0011] The above-described configuration makes it possible to smoothly adjust the oil temperature with a simple configuration, and also makes it possible to reduce the size of the refrigeration device and reduce costs.

[0012] Additionally, a control method executed by the above-described refrigeration device is provided. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram showing the overall configuration of a refrigerator according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating a configuration of a first air heat exchanger in a refrigerator according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a perspective view showing the configuration of a first air heat exchanger in a refrigerator according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a flowchart showing air volume control of a blower in a refrigerator according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a state transition diagram illustrating bypass flow rate control in a refrigerator according to an embodiment of the present disclosure. [Figure 6]FIG. 6A is a diagram showing the relationship between the target condensing pressure and the outside air temperature in a refrigerator according to an embodiment of the present disclosure, FIG. 6B is a diagram schematically explaining the flow control of the bypass circuit, and FIG. 6C is a diagram showing the correspondence between the open / closed states of the solenoid valve. [Figure 7] FIG. 7 is a diagram showing the overall configuration of a refrigerator according to another embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram showing the overall configuration of a refrigerator according to still another embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] One or more embodiments of the present disclosure will be described below with reference to the drawings, but the embodiments of the present disclosure are not limited to the specific embodiments described below. Note that the same reference numerals throughout the drawings indicate the same or corresponding parts.

[0015] The present disclosure relates to a refrigeration system (100) and a control method thereof. The refrigeration system (100) according to an embodiment of the present disclosure includes a compressor (1), an oil separator (2) that separates refrigerant and oil from the compressor (1), a condenser (3a) that condenses the refrigerant separated by the oil separator (2), an oil cooler (7) that cools the oil separated by the oil separator, a blower (9a) that blows air to the condenser (3a) and the oil cooler (7), and a blower control unit (17) that controls the air volume of the blower (9a). In the refrigeration system (100), the condenser (3a) and the oil cooler (7) are integrated into a single air heat exchanger (20a). The blower control unit (17) adjusts the degree of cooling by the oil cooler (7) by controlling the air volume of the blower (9a) based on an index value (e.g., condensation pressure, condensation temperature) related to the condenser (3a).

[0016] The above-described configuration makes it possible to smoothly adjust the oil temperature with a simple configuration, and also makes it possible to reduce the size of the refrigeration device and reduce costs.

[0017] More specifically, since there is a correlation between the oil temperature and the condensation pressure (and condensation temperature) of the condenser (3), incorporating the condenser (3a) and the oil cooler (7) into a single air heat exchanger (20a) and controlling the blower (9a) based on index values ​​(e.g., condensation pressure and condensation temperature) related to the condenser (3a) enables simultaneous control of the oil temperature. This allows for smooth adjustment of the temperature of the oil returned to the compressor (1) even during low outdoor air temperatures with a simple configuration. Furthermore, integrating the condenser (3a) and the oil cooler (7) into a single air heat exchanger (20a) eliminates the need for an additional air heat exchanger for the oil cooler, compared to a configuration in which the condenser and the oil cooler are each dedicated to adjacent cooling fans. This increases the design flexibility of the air heat exchanger and minimizes the area occupied by the air heat exchanger in the refrigeration system, thereby contributing to the miniaturization of the refrigeration system and the expected cost reduction.

[0018] In a preferred embodiment, the refrigeration system (100) includes a bypass circuit that returns oil from the oil separator (2) to the compressor (1) without passing through the oil cooler (7). The bypass circuit includes valve means (8a, 8b / 8c) that change the flow rate of oil to the bypass circuit. When the outside air temperature is low, an excessive drop in oil temperature can increase the viscosity of the oil, which can reduce the supply of oil to the compressor (1) or excessively cool the temperature inside the compressor (1), potentially causing a breakdown of the compressor (1). By returning a portion of the high-temperature oil discharged from the compressor (1) to the compressor (1) without cooling it, an excessive drop in oil temperature can be prevented. This prevents an increase in oil viscosity and can prevent a reduction in the supply of oil or a breakdown of the compressor (1). In addition, at this time, the temperature of the oil is generally kept at an appropriate temperature by controlling the blower (9a), so that the bypass circuit can be minimized in capacity and function, thereby achieving cost reduction.

[0019] In a preferred embodiment, the refrigeration system (100) further includes a temperature sensor (14) that detects the oil temperature, and a bypass control unit (17) that controls the valve means (88a, 88b / 8c) to change the flow rate of oil to the bypass circuit based on the oil temperature detected by the temperature sensor (14). This makes it possible to reliably prevent an excessive drop in oil temperature by changing the flow rate of oil to the bypass circuit in response to a drop in oil temperature. This in turn makes it possible to avoid oil clogging in the oil cooler (insufficient oil supply to the compressor) due to an increase in oil viscosity, and to avoid abrupt changes in the cycle.

[0020] In a preferred embodiment, the valve means is one or more solenoid valves (8a, 8b) that change the flow rate by opening or closing, and the open / closed state (e.g., ON / OFF) of the one or more solenoid valves (8a, 8b) is determined according to at least a threshold value for the oil temperature (e.g., a lower limit temperature, an intermediate temperature, an upper limit temperature, etc.). This makes it possible to adjust the flow rate to the bypass circuit by simply controlling the open / closed state of the solenoid valves (8a, 8b).

[0021] In a particular embodiment, the valve means is a solenoid valve (8c) that changes the flow rate by changing the opening degree.

[0022] In a preferred embodiment, the refrigeration system (100) further includes a pressure sensor (15) that detects the discharge pressure (condensation pressure) of the compressor (1) as an index value related to the condenser (3a). The blower control unit (17) increases or decreases the airflow rate based on a comparison between a target pressure according to the outside air and the discharge pressure detected by the pressure sensor (15). With this configuration, the oil temperature is generally kept at an optimum temperature by controlling the blower (9a).

[0023] In a preferred embodiment, the oil cooler (7) and the condenser (3a) are provided in parallel with the flow of air blown by the blower (9a). The blower control unit (17) adjusts the degree of cooling by the oil cooler (7) and the condensation pressure (and condensation temperature) of the condenser (3a) by controlling the air volume of the blower (9a) based on the index value. With this configuration, the heat transfer areas of the oil cooler (7) and the condenser (3a) in the air heat exchanger (20a) can be easily optimized according to the expected operating conditions of the refrigeration system (100), and both the degree of cooling by the oil cooler (7) and the condensation pressure (and condensation temperature) can be suitably adjusted based on the index value.

[0024] In a preferred embodiment, the bypass control unit (17) controls the flow rate of oil to the bypass circuit using the valve means (8a, 8b / 8c) when the refrigeration system (100) is started up, when the blower (9a) is not operating normally, or when the control of the blower (9a) is not functioning normally. This makes it possible to deal with cases where the oil temperature has dropped too low due to, for example, the outside air temperature being low when the refrigeration system (100) is started up, or the blower (9a) not operating normally or the control of the blower (9a) not functioning normally.

[0025] In a preferred embodiment, the oil cooler (7) is provided above the condenser (3a) in the air heat exchanger (20a). While oil is normally discharged by gravity during oil change, providing the oil cooler (7) above the condenser (3a) in the air heat exchanger (20a) allows the oil in the oil cooler (7) to be drained using the space below the oil cooler (7). This eliminates the need to provide a separate space below the air heat exchanger for draining oil, thereby enabling the refrigeration system to be more compact.

[0026] A method for controlling a refrigeration system (100) according to an embodiment of the present disclosure includes a step (S103) of acquiring an index value related to a condenser (3a) that condenses refrigerant separated in an oil separator (2) in the refrigeration system (100), and steps (S104 to S106) of controlling, based on the index value related to the condenser (3a), the air volume of a blower (9a) that blows air to an air heat exchanger (20a) integrated with an oil cooler (7) that cools oil separated in the oil separator (2) and the condenser (3a). The degree of cooling by the oil cooler (7) is adjusted by controlling the air volume based on the index value related to the condenser (3a) (S104 to S106).

[0027] In a preferred embodiment, the control method includes the steps of detecting the temperature of the oil using a temperature sensor (14) and varying the flow rate of oil (based on the opening and closing of 9a, 9b, or the opening degree of 9c) to a bypass circuit that returns oil from the oil separator (2) to the compressor (1) without passing through the oil cooler (7) based on the oil temperature detected by the temperature sensor.

[0028] Hereinafter, a refrigeration device according to one or more embodiments of the present disclosure will be described in more detail with reference to FIGS.

[0029] FIG. 1 is a diagram showing the overall configuration of a refrigerator 100 according to an embodiment of the present disclosure. The refrigerator 100 shown in FIG. 1 is an outdoor-installed screw-type refrigerator with a two-stage compression system. Note that an outdoor-installed two-stage screw compression refrigerator is an example of a refrigeration device to which the configuration according to an embodiment of the present disclosure can be applied, and the configuration of the refrigerator is not limited thereto. The refrigerator 100 is also called a condensing unit.

[0030] First, a refrigerant circuit in a refrigerator 100 shown in Fig. 1 will be described below. In Fig. 1, the refrigerant circuit of the refrigerator 100 is indicated by solid lines, and the flow of refrigerant is indicated by solid arrows. As shown in Fig. 1, the refrigerator 100 includes a compressor 1 that draws in refrigerant gas discharged from an evaporator 12, compresses the refrigerant, and discharges the compressed refrigerant, an oil separator 2 that separates the refrigerant discharged from the compressor 1 from refrigeration oil (hereinafter simply referred to as oil), a condenser 3 that condenses the refrigerant separated in the oil separator 2 by heat exchange with air, and a receiver 4 into which the condensed refrigerant from the condenser 3 flows. In the embodiment shown in Fig. 1, two condensers 3 are provided, which are referred to as a first condenser 3a and a second condenser 3b. The refrigerant separated in the oil separator 2 is then branched and guided to the first condenser 3a and the second condenser 3b, where it is condensed and then merges with the receiver 4.

[0031] As shown in FIG. 1, the chiller 100 further includes a subcooler 5 that subcools the refrigerant from the receiver 4. The refrigerant subcooled by the subcooler 5 is depressurized by an expansion valve 13 and supplied to the evaporator 12. The subcooler 5 is provided with a subcooling expansion valve 6, and a portion of the refrigerant is depressurized by the subcooling expansion valve 6 and enters the subcooler 5, where it exchanges heat with the refrigerant from the receiver 4 to subcool the refrigerant from the receiver 4, and is then returned to the intermediate stage of the compressor 1.

[0032] In the evaporator 12, the refrigerant absorbs heat from the air, water, etc., evaporates, and the refrigerant gas is discharged from the evaporator 12 to the compressor 1. In the configuration shown in Fig. 1, the evaporator 12 and expansion valve 13 enclosed by the dotted line are typically parts outside the refrigeration unit 100 that are prepared by the user, and constitute a showcase, a freezer / refrigerator, a unit cooler, an ice maker, etc.

[0033] The compressor 1 shown in Fig. 1 is a screw-type two-stage compression compressor. However, the compressor 1 is not limited to a screw-type compression compressor, and may be a compression compressor other than the screw type (for example, a scroll type, a reciprocating type, a rotary type, or a turbo type), or may be a single-stage compressor instead of a two-stage compressor.

[0034] The refrigerant used in the refrigerator 100 is not particularly limited, but may be a single refrigerant such as R32, R134a, or R1234yf; a near-azeotropic refrigerant such as R410A or R404A; a non-azeotropic refrigerant mixture such as R448A, R449A, R463A, R466A, R407C, R407H, R454B, R454C, or R455A; or a mixture thereof. Using a refrigerant with a low GWP (Global Warming Potential) can reduce the impact on global warming caused by refrigerant leakage from the refrigerator. For example, the refrigerant R448A can be used, which has a global warming potential that is approximately 64% lower than that of the refrigerant R404A and approximately 33% lower than that of the refrigerant R410A.

[0035] In Fig. 1, the oil circuit of the chiller 100 is further indicated by dotted lines, and the direction of oil flow is indicated by dotted arrows. The chiller 100 includes an oil cooler 7 that cools the oil. The oil is discharged from the compressor 1 together with the refrigerant and separated from the refrigerant in the oil separator 2, and flows into the oil cooler 7 via piping. The oil cooler 7 cools the refrigerant that has flowed in by exchanging heat with air. After being cooled by the oil cooler 7, the oil is returned to the compressor 1 via piping.

[0036] Furthermore, the refrigeration machine 100 has an oil circuit that returns oil to the compressor 1 via the oil cooler 7, as well as a bypass circuit that returns the oil separated in the oil separator 2 to the compressor 1 without passing through the oil cooler 7. A portion of the oil that is discharged from the compressor 1 together with the refrigerant and separated in the oil separator 2 may be returned to the compressor 1 via the bypass circuit without being cooled by the oil cooler 7. Solenoid valves 8a and 8b are provided in the bypass circuit, and the flow rate of oil returned via the bypass circuit (bypass flow rate) is adjusted by controlling the opening and closing of the solenoid valves 8a and 8b.

[0037] The chiller 100 is designed to operate within a predetermined ambient temperature range (e.g., −10°C to +40°C), but is also designed to provide sufficient oil cooling even at the upper limit of the operating temperature range (e.g., +40°C). On the other hand, when the ambient temperature is near the lower limit of the operating temperature range (e.g., −10°C), the oil may be overcooled, resulting in an excessive drop in oil temperature. Furthermore, when starting up from a stopped state in low ambient air, the oil may be fully cooled, resulting in an excessive drop in oil temperature. An excessive drop in oil temperature can increase the oil viscosity, reducing the oil supply to the compressor 1 or excessively cooling the temperature inside the compressor 1, leading to compressor 1 failure. The bypass circuit described above prevents an excessive drop in oil temperature by returning a portion of the high-temperature oil discharged from the compressor 1 to the compressor 1 without cooling it in the oil cooler 7. This eliminates the need for an oil heater in the air heat exchanger.

[0038] As shown in Fig. 1, in the embodiment being described, the first condenser 3a and the oil cooler 7 are integrated to form a single air heat exchanger (hereinafter referred to as the first air heat exchanger) 20a. In contrast, the second condenser 3b independently forms a single air heat exchanger (hereinafter referred to as the second air heat exchanger) 20b. Fig. 1 also shows a preferred arrangement of the first condenser 3a and the oil cooler 7, and in the embodiment being described, the oil cooler 7 is provided above the first condenser 3a in the first air heat exchanger 20a.

[0039] The chiller 100 includes a first fan 9a for blowing air to the first air heat exchanger 20a (the first condenser 3a and the oil cooler 7) and a second fan 9b for blowing air to the second air heat exchanger 20b (the second condenser 3b). The first fan 9a blows air drawn in from the outside toward the first air heat exchanger 20a, or draws air from the outside through the first air heat exchanger 20a, and then blows the air to the first condenser 3a and the oil cooler 7, which are provided in parallel with the air flow. The same applies to the second fan 9b. In FIG. 1, the fans 9a and 9b are depicted as being arranged in a top-flow configuration.

[0040] 1, the chiller 100 further includes various sensors 14-16 and a control device 17. More specifically, the various sensors 14-16 include an oil temperature sensor 14 provided after the bypass circuit and the pipe from the oil cooler 7 join together and before the oil is returned to the compressor 1, a discharge pressure sensor 15 provided in the oil separator 2, and an outside air temperature sensor 16 provided in the second air heat exchanger 20b (condenser 3b). The control device 17 is connected to actuators such as the blowers 9a, 9b and the solenoid valves 8a, 8b, and sensors such as the oil temperature sensor 14, the discharge pressure sensor 15, and the outside air temperature sensor 16.

[0041] The control device 17 controls the fans 8a and 8b based on signals from the discharge pressure sensor 15 and the outside air temperature sensor 16, and controls the volume of air sent to the first air heat exchanger 20a (the first condenser 3a and the oil cooler 7) and the second air heat exchanger 20b (the second condenser 3b). The control device 17 adjusts the degree of cooling by the oil cooler 7 by controlling the volume of air sent from the fans 9a and 9b based on index values ​​(condensation pressure, condensation temperature) related to the condensers 3a and 3b. In the embodiment described below, the index value is specifically the condensation pressure, and the discharge pressure measured by the discharge pressure sensor 15 provided in the receiver 2, which correlates with the condensation pressure, is also used. The control device 17 also controls the opening and closing of the solenoid valves 8a and 8b in the bypass circuit based on the oil temperature (immediately before) returned to the compressor 1, detected by the oil temperature sensor 14, to adjust the bypass flow rate and return oil to the compressor 1 at an appropriate oil temperature. The control device 17 constitutes a blower control unit and a bypass control unit in the embodiment of the present disclosure.

[0042] Fig. 2 is a diagram illustrating the arrangement of the first condenser 3a and the oil cooler 7 in the first air heat exchanger 20a in the chiller 100 according to the embodiment of the present disclosure. Fig. 3 is a perspective view illustrating the configuration of the first air heat exchanger 20a in the chiller 100 according to the embodiment of the present disclosure. Note that the structure illustrated in Figs. 2 and 3 is a simplified representation of the structure of the first air heat exchanger 20a. In other words, the actual structure of the first air heat exchanger 20a is typically more complex (having a larger number of columns and pipes) than the structure illustrated in Figs. 2 and 3.

[0043] As shown in Figures 2 and 3, the first condenser 3a and the oil cooler 7 are arranged in parallel with respect to the air flow and integrally constitute a first air heat exchanger 20a. The first air heat exchanger 20a includes a plurality of fins 29 and pipes 21 and 25 that penetrate the plurality of fins 29. In Figure 2, the area indicated by gray hatching corresponds to the oil cooler 7 in the upper row, and the area indicated by white corresponds to the first condenser 3a in the lower row. The pipe 21 constitutes the first condenser 3a, and refrigerant flows through it. The pipe 25 constitutes the oil cooler 7, and oil flows through it. The boundary between the oil cooler 7 and the first condenser 3a is indicated by a dotted line.

[0044] The first condenser 3a is connected to a refrigerant inlet 22 and a refrigerant outlet 23. The first condenser 3a includes a pipe 21 that penetrates fins 29 and travels back and forth in a direction perpendicular to the plane of the drawing, and the pipe 21 is connected to the refrigerant inlet 22 via a header 22a and to the refrigerant outlet 23 via a header 23a. The refrigerant inlet 22 is connected to the oil separator 2, and the refrigerant outlet 23 is connected to the receiver 4.

[0045] The oil cooler 7 is connected to an oil inlet 26 and an oil outlet 27. The oil cooler 7 includes a pipe 25 that penetrates fins 29 and travels back and forth in a direction perpendicular to the plane of the drawing, and the pipe 25 is connected to the oil inlet 26 via a header 26a and to the oil outlet 27 via a header 27a. The oil inlet 26 is connected to the oil separator 2, and the oil outlet 27 is connected to the compressor 1.

[0046] 2 and 3, by adopting a configuration in which the first condenser 3a and the oil cooler 7 are integrated into one air heat exchanger 20a, compared to a configuration in which the condenser and the oil cooler are each dedicated and adjacent and cooled by one fan, it is not necessary to add an air heat exchanger for an independent oil cooler, which increases the design freedom of the air heat exchanger 20a and minimizes the area of ​​the chiller 100 occupied by the air heat exchanger 20a. As a result, the chiller 100 can be made smaller, and costs can also be reduced.

[0047] Furthermore, as shown in FIGS. 2 and 3 , the oil cooler 7 and the condenser 3a are integrated into a single air heat exchanger 20a so as to be arranged in parallel with the air flow blown by the blower 9a. This allows the ratio of the heat transfer areas of the oil cooler 7 and the condenser 3a in the air heat exchanger 20a to be designed according to the expected operating conditions of the chiller 100, thereby optimizing the heat transfer area of ​​each, thereby increasing the design flexibility of the air heat exchanger. For example, if the oil coolers are arranged in series with the air flow rather than in parallel with the air flow (i.e., if the condenser and oil cooler are arranged in rows), optimizing the heat transfer area becomes difficult. Furthermore, if the oil cooler is arranged in series with the air flow, performance is reduced because either the condenser or the oil cooler cannot directly come into contact with the outside air. In particular, if the oil cooler is located on the front side exposed to the outside air, the condenser cannot condense sufficiently due to the large heat capacity of the oil.

[0048] When the chiller 100 is in operation, the refrigerant and refrigeration oil flow in the directions indicated by the arrows. To explain the flow of oil, the oil enters the oil cooler 7 from the oil separator 2 via the header 26a and the oil inlet 26, flows through the pipe 25 while exchanging heat with the air in the oil cooler 7, exits the oil cooler 7 via the header 27a and the oil outlet 27, and is returned to the compressor 1.

[0049] The refrigeration oil is sealed in the oil cooler 7 during the manufacturing process of the refrigeration machine 100 or during the on-site installation process of the refrigeration machine 100. Furthermore, during maintenance work on the refrigeration machine 100, old refrigeration oil is discharged from the oil cooler 7, and new refrigeration oil is sealed in the oil cooler 7.

[0050] In the oil system shown in FIG. 1, an oil inlet / outlet port 10 is provided in the piping leading from the oil cooler 7 to the compressor 1 after merging with the bypass circuit. To inject oil, a vacuum is created inside the equipment and oil is drawn into the equipment from the oil outlet 27 side (oil inlet / outlet port 10) at the bottom of the air heat exchanger 20a. When the oil cooler 7 is filled to the top, the drawn-up oil flows down from the oil inlet 26 to the oil separator 2. Therefore, oil filling can be confirmed by confirming that the oil has accumulated to a predetermined position in the oil separator 2. In addition, oil is discharged by gravity from the oil inlet 27 side (oil inlet / outlet port 10) inside the oil cooler 7. Oil is discharged from the oil separator 2 to the inlet of the oil cooler 7 through the oil outlet 11.

[0051] Since the oil outlet 27 is located at the bottom, more preferably below all of the pipes 25 that make up the oil cooler 7, the oil inside the air heat exchanger can be reliably drained. When changing oil, the oil is discharged by gravity, but by providing the oil cooler 7 above the first condenser 3a in the air heat exchanger 20a, the oil in the oil cooler 7 can be drained using the space S between the oil cooler 7 and the bottom surface 30 of the refrigerator. This eliminates the need to secure a separate space below the air heat exchanger to drain the oil, making it possible to downsize the refrigerator.

[0052] Furthermore, if oil is sealed in the oil cooler 7 so that it enters from above and leaves from below, and the oil cooler 7 is positioned above the oil separator 2, the oil will accumulate in the oil separator 2. On the other hand, by sealing the oil in the oil cooler 7 so that it enters from below and leaves from above, as in the embodiment described above, it is possible to alleviate restrictions on the placement of the oil cooler 7 and the oil separator 2, and therefore the refrigerator 100 can be made more compact.

[0053] Hereinafter, the air volume control by the blower 9 in the refrigerator 100 will be described in more detail with reference to Fig. 4. Fig. 4 is a flowchart showing the air volume control by the blower 9 in the refrigerator 100 according to an embodiment of the present disclosure. The air volume control shown in Fig. 4 starts from step S100.

[0054] In step S101, the control device 17 (blower control unit) measures the outside air temperature using the outside air temperature sensor 16. In step S102, the control device 17 (blower control unit) determines a target condensing pressure according to the outside air temperature measured in step S101.

[0055] FIG. 6(A) shows the relationship of the target condensation pressure to the outside air temperature in the chiller 100 according to an embodiment of the present disclosure. As shown in FIG. 6(A), the target condensation pressure is determined by the outside air temperature. The control device 17 (blower control unit) sets this target condensation pressure and controls the air volume (the rotation speed of the blower motor) of the blower 9. Note that although there are two air heat exchangers 20a, 20b and two blowers 9a, 9b, the air volumes of the two blowers 9a, 9b only need to be controlled to the same value.

[0056] In step S103, the control device 17 (blower control unit) measures the discharge pressure using the discharge pressure sensor 15. In step S104, the control device 17 (blower control unit) compares the discharge pressure measured by the discharge pressure sensor 15 in step S103 with the target condensation pressure determined in step S102 according to the outside air temperature, and branches the process.

[0057] If it is determined in step S104 that the discharge pressure measured by discharge pressure sensor 15 is lower than the target condensation pressure determined in accordance with the outside air temperature, the process branches to step S105. In step S105, the control device 17 (blower control unit) reduces the airflow rate of the blower 9, for example, by a predetermined amount. On the other hand, if it is determined in step S104 that the discharge pressure measured by the discharge pressure sensor 15 is higher than the target condensation pressure determined in accordance with the outside air temperature, the process branches to step S106. In step S106, the control device 17 (blower control unit) increases the airflow rate of the blower 9, for example, by a predetermined amount. After the airflow rate of the blower 9 is increased or decreased in step S105 or step S106, control returns to step S101. On the other hand, if it is determined in step S104 that the discharge pressure measured by the discharge pressure sensor 15 is equal to the target condensation pressure determined according to the outside air temperature, the air volume is not changed and control returns to step S101.

[0058] In the determination in step S104, a predetermined tolerance may be set for the target condensation pressure. In this case, if it is determined in step S104 that the discharge pressure measured by discharge pressure sensor 15 is higher or lower than the target condensation pressure determined according to the outside air temperature by a predetermined threshold, the air volume of the blower is increased or decreased. In the above-described embodiment, the air volume is controlled based on the target condensation pressure and the discharge pressure (which is correlated with the condensation pressure). However, the air volume may also be controlled based on the target condensation temperature and the condensation temperature using a temperature sensor.

[0059] The oil temperature is strongly affected by the discharge pressure of the compressor 1. Because the discharge pressure of the compressor 1 depends on the condensation pressure (condensation temperature) of the condenser 3, there is a correlation between the oil temperature and the condensation pressure (condensation temperature). By incorporating the condenser 3a and the oil cooler 7 into one air heat exchanger 20a and implementing fan control to control the airflow rate of the blower 9 so that the index values ​​(condensation pressure, condensation temperature) reach set target values ​​(target condensation pressure, target condensation temperature), it becomes possible to smoothly adjust the oil temperature at the same time as the refrigerant condensation pressure (and condensation temperature).

[0060] Hereinafter, with reference to FIGS. 5, 6(B), and 6(C), bypass flow rate control by opening and closing the solenoid valves 8a and 8b in the refrigerator 100 will be described. FIG. 5 is a state transition diagram showing bypass flow rate control in the refrigerator 100 according to an embodiment of the present disclosure. The bypass flow rate control shown in FIG. 5 is realized by transitions between at least four states (Step 0 to Step 3). The correspondence between each of the four states and the open / closed states of the solenoid valves 8a and 8b is shown in the table of FIG. 6(C). Note that in the embodiment described, one of the two solenoid valves 8a and 8b is a main valve, and the other is a sub-valve, and the flow rate when the main valve is "open" is greater than the flow rate when the sub-valve is "open." In FIG. 5, each state (Step 0 to Step 3) is accompanied by the "open" or "closed" state of the main valve (left) and the sub-valve (right).

[0061] As shown in Figures 5 and 6(C), the first state (Step 0) is a state in which both the main valve and the sub-valve are in the "open" state, with the largest bypass flow rate and the smallest degree of oil cooling. The second state (Step 1) is a state in which only the main valve is in the "open" state (the sub-valve is in the "closed" state), with the second largest bypass flow rate and the second smallest degree of oil cooling. The third state (Step 2) is a state in which only the sub-valve is in the "open" state (the main valve is in the "closed" state), with the third largest bypass flow rate and the third smallest degree of oil cooling. The fourth state (Step 3) is a state in which both the main valve and the sub-valve are in the "closed" state, with the smallest bypass flow rate and the largest degree of oil cooling.

[0062] The control state transitions between the four states shown in Fig. 5 by satisfying a condition that includes at least a threshold value for the oil temperature. In the embodiment described below, a lower limit value, an intermediate value, and an upper limit value for the oil temperature are used as the threshold values. In addition to the threshold value for the oil temperature, a condition for the continuation of the state may also be added to the conditions.

[0063] The first state (Step 0) is a state with the maximum bypass flow rate and the minimum degree of cooling. In the first state (Step 0), when the condition that the oil temperature is equal to or higher than the intermediate temperature is satisfied, the control state transitions to the second state (Step 1) in response to the condition being satisfied.

[0064] By transitioning to the second state (Step 1), the bypass flow rate decreases and the degree of oil cooling increases compared to the first state (Step 0). When the condition that the oil temperature is equal to or higher than the upper limit temperature is satisfied in the second state (Step 1), the control state transitions to the third state (Step 2) in response to the condition being satisfied. On the other hand, when the condition that the oil temperature is lower than the lower limit temperature is satisfied in the second state (Step 1), the control state transitions to the first state (Step 0) in response to the condition being satisfied, returning to the state with the maximum bypass flow rate and the minimum degree of cooling.

[0065] By transitioning to the third state (Step 2), the bypass flow rate decreases compared to the second state (Step 1) (the flow rate when the sub-valve is "open" is smaller than the flow rate when the main valve is "open"), and the degree of oil cooling increases. In the third state (Step 2), if the condition that the oil temperature remains at or above the upper limit temperature (for example, for a predetermined time or more) is met, the control state transitions to the fourth state (Step 3) in response to the condition being satisfied. On the other hand, in the third state (Step 2), if the condition that the oil temperature remains below the intermediate temperature (for example, for a predetermined time or more) is met, the control state transitions to the second state (Step 1) in response to the condition being satisfied, returning to a state with a larger bypass flow rate and a smaller degree of cooling.

[0066] By transitioning to the fourth state (Step 3), the bypass flow rate is minimized and the degree of oil cooling is maximized. When the condition that the oil temperature is below the intermediate temperature is met in the fourth state (Step 3), the control state transitions to the third state (Step 2) in response to the condition being met, returning to a state with a larger bypass flow rate and a smaller degree of cooling. The fourth state (Step 3) remains until the condition that the oil temperature is below the intermediate temperature is met in the fourth state (Step 3). As mentioned above, the oil cooling is designed to provide sufficient cooling even at the upper limit of the operating temperature range (e.g., +40°C). Therefore, if the oil cannot be cooled in time in the fourth state (Step 3) (e.g., at maximum airflow) and the oil temperature continues to rise, an error occurs because the oil is outside the operating temperature range.

[0067] 5 to be the initial state can be determined depending on the outside air temperature. For example, if the outside air temperature is equal to or higher than a predetermined threshold temperature, the fourth state (Step 3) may be started, and if the outside air temperature is lower than the predetermined threshold temperature, the first state (Step 0) may be started.

[0068] Figure 6(B) is a diagram in which the state transitions shown in Figure 5 are organized by temperature range. In Figure 6(B), a black circle (●) indicates a condition of being equal to or higher than a predetermined temperature, and a white circle (○) indicates a condition of being lower than the predetermined temperature.

[0069] First, the description will be given assuming that the outside air temperature is below a predetermined threshold temperature and the operation starts from the first state (Step 0). This state corresponds to starting with the bypass flow rate set to maximum in response to the low outside air temperature. When the operation of the chiller 100 starts and the oil temperature rises and reaches the intermediate temperature or higher, the control state transitions to the second state (Step 1) (1). On the other hand, even when the operation of the chiller 100 starts, if the oil temperature does not rise much in the first state (Step 0) and remains below the intermediate temperature, the control state is maintained in the first state (Step 0).

[0070] In the second state (Step 1), even if the oil temperature falls below the intermediate temperature, the control state is maintained in the second state (Step 1) until it falls below the lower limit temperature (2). If the oil temperature continues to rise in the second state (Step 1) and exceeds the upper limit temperature, the control state transitions to the third state (Step 2) (3). In the third state (Step 2), even if the oil temperature falls below the upper limit temperature, the control state is maintained in the third state (Step 2) until it falls below the intermediate temperature (4). If the oil temperature does not decrease in the third state (Step 2) and remains above the upper limit temperature, the control state transitions to the fourth state (Step 3) (5). If the oil temperature is cooled to the maximum in the fourth state (Step 3) and falls below the intermediate temperature, the control state transitions to the third state (Step 2) (6). If the oil temperature remains below the intermediate temperature in the third state (Step 2), the control state transitions to the second state (Step 1) (7). In the second state (Step 1), when the temperature falls below the lower limit temperature, the control state transitions to the first state (Step 0) (8).

[0071] 5, 6(B), and 6(C), in the described embodiment, the control device 17 (bypass control unit) sets an upper limit, a lower limit, and an intermediate limit for the oil temperature, and executes control to determine the open / close state of the solenoid valves of the bypass circuit according to the temperature of the oil returned to the compressor 1. The opening and closing of the solenoid valves 8a and 8b may be determined periodically (for example, every 30 seconds), which prevents the operation of the solenoid valves 8a and 8b from changing frequently, thereby making it possible to moderate fluctuations in the cycle.

[0072] Furthermore, the airflow control described with reference to Figures 4 and 6(A) and the bypass flow rate control described with reference to Figures 5, 6(B), and 6(C) are executed in parallel. The bypass flow rate is maintained while the airflow rate control is maintaining the temperature within an appropriate range. For example, while the airflow rate control is maintaining the temperature within an appropriate range, the fourth state (Step 3) may be maintained.

[0073] The control device 17 (bypass control unit) controls the oil flow rate to the bypass circuit using the solenoid valves 8a and 8b when the chiller 100 starts up (when started up at low outside air temperature), when the blower 9a is not operating properly, or when the control of the blower 9a is not functioning properly. This allows for countermeasures when the oil temperature drops too low due to low outside air temperature when the chiller 100 starts up, or when the blower 9a is not operating properly or is not functioning properly. This in turn gradually prevents oil clogging in the oil cooler (insufficient oil supply to the compressor) due to increased oil viscosity caused by excessive cooling of the oil temperature, thereby avoiding sudden changes in the cycle. Furthermore, by performing the above-mentioned air volume control in parallel, the oil temperature is generally kept at an optimum temperature, allowing the bypass path to be minimized in capacity and function, thereby reducing costs.

[0074] An alternative embodiment will now be described with reference to FIGS.

[0075] Fig. 7 is a diagram showing the overall configuration of a refrigerator 100 according to another embodiment of the present disclosure. The other embodiment shown in Fig. 7 has a similar configuration to the embodiment shown in Fig. 1, and therefore the following description will focus on the differences.

[0076] As shown in Fig. 7, the refrigerator 100 has a refrigerant circuit similar to that shown in Fig. 1. Regarding the oil circuit, in the configuration shown in Fig. 1, two solenoid valves 8a and 8b whose opening and closing can be controlled are provided in the bypass circuit, but in the configuration shown in Fig. 7, one solenoid valve 8c whose opening degree is variable is provided in the bypass circuit.

[0077] Similar to the chiller 100 shown in FIG. 1 , the control device 17 controls the fans 8a and 8b based on signals from the discharge pressure sensor 15 and the outside air temperature sensor 16, thereby controlling the volume of air sent to the first air heat exchanger 20a (the first condenser 3a and the oil cooler 7) and the second air heat exchanger 20b (the second condenser 3b and the first subcooler 5′). More specifically, the control device 17 controls the volume of air sent from the fans 9a and 9b based on index values ​​related to the condensers 3a and 3b, thereby adjusting the degree of cooling by the oil cooler 7. The control device 17 also controls the aperture of the solenoid valve 8c in the bypass circuit based on the oil temperature returned to the compressor 1 detected by the oil temperature sensor 14, thereby adjusting the bypass flow rate and returning oil to the compressor 1 at an appropriate oil temperature.

[0078] Note that the control of the opening degree of the solenoid valve 8c based on the oil temperature can be achieved by, for example, associating a specific valve opening degree of the solenoid valve 8c with the opening and closing states of the solenoid valves 8a and 8b in place of the opening and closing states of the solenoid valves 8a and 8b in the control of the transition between the states (Steps 0 to 3) associated with the opening and closing states of the two solenoid valves 8a and 8b as shown in Figures 6(B) and 6(C). For example, the first to fourth states (Steps 0 to 3) can be associated with 100% (corresponding to both the main valve and the sub-valve being "open"), 60% (corresponding to only the main valve being "open"), 30% (corresponding to only the sub-valve being "open"), and 0% (corresponding to both the main valve and the sub-valve being "closed"). Furthermore, the number of temperature thresholds can be increased to set more opening degrees.

[0079] In this way, instead of the solenoid valves 8a and 8b whose opening and closing are controlled, the solenoid valve 8c whose opening degree is variably controlled can be provided in the bypass circuit. In this case, the flow rate of oil returned through the bypass circuit (bypass flow rate) is adjusted by controlling the opening degree of the solenoid valve.

[0080] Fig. 8 is a diagram showing the overall configuration of a refrigerator 100 according to yet another embodiment of the present disclosure. The yet another embodiment shown in Fig. 8 has a similar configuration to the embodiments shown in Fig. 1 and Fig. 7, and therefore the following description will focus on the differences.

[0081] As shown in FIG. 8, the chiller 100 has a refrigerant circuit similar to that shown in FIG. 1, but the arrangement of the condenser 3a and the oil cooler 7 is different from that shown in FIG. 1. In the configuration shown in FIG. 1, the oil cooler 7 is provided above the condenser 3a in the air heat exchanger 20a, whereas in the configuration shown in FIG. 8, the oil cooler 7 is provided below the condenser 3a in the air heat exchanger 20a. The condenser 3a and the oil cooler 7 are upside down compared to the arrangement shown in FIG. 1, but this can be achieved by ensuring space below the oil cooler 7 for draining oil. Even in this case, the oil cooler 7 and the condenser 3a are integrated into a single air heat exchanger 20a and are preferably provided in parallel with the flow of air blown by the blower 9a.

[0082] As described above, according to the embodiments of the present disclosure, a refrigerator is provided that is capable of smoothly adjusting the oil temperature with a simple configuration, and that is also compact and can reduce costs.

[0083] It should be noted that the embodiments of the present invention are not limited to the above-described embodiments and may include various modifications. For example, the above-described embodiments have been described in detail for ease of understanding, and are not necessarily limited to those including all of the described features. Furthermore, some of the features of one embodiment may be replaced with features of another embodiment, or features of one embodiment may be added to features of another embodiment. Furthermore, some of the features of each embodiment may be added to, deleted from, or replaced with other features. [Explanation of symbols]

[0084] 100...refrigerating unit, 1...compressor, 2...oil separator, 3a, 3b...condenser, 4...receiver, 5...subcooler, 6...expansion valve, 7...oil cooler, 8a, 8b, 8c...solenoid valve, 9a, 9b...blower, 10...oil filling / discharge port, 11...oil discharge port, 12...evaporator, 13...expansion valve, 14...oil temperature sensor, 15...discharge pressure sensor, 16...outside air temperature sensor, 17...control device, 20a, 20b...air heat exchanger, 21, 25...piping, 22...refrigerant inlet, 23...refrigerant outlet, 26...oil inlet, 27...oil outlet, 29...fin, 22a, 23a, 26a, 27a...header, 30...bottom of refrigerator

Claims

1. 1. A refrigeration device comprising: A compressor; an oil separator for separating refrigerant and oil from the compressor; a condenser for condensing the refrigerant separated by the oil separator; an oil cooler that cools the oil separated by the oil separator; a blower for blowing air to the condenser and the oil cooler; a blower control unit for controlling the air volume of the blower; the condenser and the oil cooler are integrated into a single air heat exchanger, and the blower control unit adjusts the degree of cooling by the oil cooler by controlling the air volume of the blower based on an index value related to the condenser.

2. 2. The refrigeration system according to claim 1, further comprising a bypass circuit for returning oil from said oil separator to said compressor without passing through said oil cooler, and a valve means for varying the flow rate of oil to said bypass circuit.

3. a temperature sensor for detecting the temperature of the oil; a bypass control unit that controls the valve means to change the flow rate of oil into the bypass circuit based on the temperature of the oil detected by the temperature sensor; The refrigeration device of claim 2 further comprising:

4. 4. The refrigeration apparatus according to claim 3, wherein the valve means is one or more solenoid valves that change the flow rate by opening or closing, and the open / closed states of the one or more solenoid valves are determined according to at least a threshold value for oil temperature.

5. 4. The refrigeration system according to claim 3, wherein said valve means is a solenoid valve that changes said flow rate by changing its opening degree.

6. 2. The refrigeration apparatus according to claim 1, further comprising a pressure sensor that detects a discharge pressure of the compressor as an index value related to the condenser, and the blower control unit increases or decreases the air volume based on a comparison between a target pressure according to outside air and the discharge pressure detected by the pressure sensor.

7. 2. The refrigeration apparatus according to claim 1, wherein the oil cooler and the condenser are provided in parallel with a flow of air blown by the blower, and the blower control unit adjusts the degree of cooling by the oil cooler as well as the condensing pressure of the condenser by controlling the air volume of the blower based on the index value.

8. 3. The refrigeration apparatus according to claim 2, wherein the control of the flow rate of oil to the bypass circuit by the bypass control unit using the valve means occurs when the refrigeration apparatus is started up, when the blower is not operating normally, or when control of the blower is not functioning normally.

9. The refrigeration apparatus according to claim 1 , wherein the oil cooler is provided in the air heat exchanger above the condenser.

10. A method for controlling a refrigeration device, comprising: acquiring an index value related to a condenser that condenses the refrigerant separated by the oil separator in the refrigeration device; a step of controlling an air volume of an oil cooler that cools the oil separated in the oil separator and an air heat exchanger that has the condenser integrated therein, based on an index value related to the condenser; wherein the degree of cooling by the oil cooler is adjusted by controlling the air volume based on an index value related to the condenser.

11. detecting the temperature of the oil with a temperature sensor; a step of varying a flow rate of oil from the oil separator to a bypass circuit that returns oil to the compressor without passing through the oil cooler, based on the temperature of the oil detected by the temperature sensor; The control method of claim 10, comprising:

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