Oil tanks and refrigerators

Abstract

The present invention provides an oil tank and a refrigerator capable of suppressing foaming of the refrigerant inside. [Solution] The oil tank comprises a lower tank that extends vertically and has a lower space inside which refrigeration oil can be stored, an upper tank provided at the upper end of the lower tank that extends horizontally and has an upper space inside, and an oil pump provided inside the lower tank that can pump refrigeration oil to the outside, with the upper tank protruding horizontally on both sides with respect to its upper end.

Description

Technical Field

[0001] The present disclosure relates to an oil tank and a refrigerator.

Background Art

[0002] In refrigerators using a refrigeration cycle, refrigerator oil is used for the purpose of lubricating movable parts including a compressor. The refrigerator oil is stored in an oil tank, and is appropriately supplied via an oil pump according to the operating state of the compressor. As a specific example of the oil tank, the one described in Patent Document 1 below is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, the refrigerant used in the refrigeration cycle is dissolved in the refrigerator oil. For this reason, for example, when the pressure in the oil tank drops sharply when the compressor is stopped, the refrigerant may gasify. As a result, the gasified refrigerant foams (foaming) in the tank. This may cause the oil pump to undergo cavitation or idling, leading to a drop in the oil supply pressure.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide an oil tank and a refrigerator capable of suppressing foaming of refrigerant.

Means for Solving the Problems

[0006] To solve the above problems, the oil tank according to this disclosure comprises a lower tank that extends vertically and has a lower space inside which refrigeration oil can be stored, an upper tank provided at the upper end of the lower tank that extends horizontally and has an upper space inside which is connected to the lower space, and an oil pump provided in the lower space that can pump the refrigeration oil to the outside, wherein the upper tank protrudes on both sides in the horizontal direction with respect to the upper end.

[0007] The refrigerator according to this disclosure comprises a refrigerator driven by a refrigeration cycle and the above-mentioned oil tank capable of supplying the refrigeration oil to the refrigerator. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an oil tank and a refrigerator capable of suppressing foaming of the refrigerant inside. [Brief explanation of the drawing]

[0009] [Figure 1] This is a circuit diagram showing the configuration of a refrigerator according to an embodiment of the present disclosure. [Figure 2] This is a perspective view showing the configuration of an oil tank according to an embodiment of the present disclosure. [Figure 3] This is a longitudinal cross-sectional view showing the configuration of an oil tank according to an embodiment of the present disclosure. [Figure 4] This is an explanatory diagram showing the behavior of refrigerant oil when foaming occurs in an oil tank according to the embodiment of this disclosure. [Modes for carrying out the invention]

[0010] (Refrigeration unit configuration) Hereinafter, the refrigerator 1 and oil tank 51 according to the embodiments of this disclosure will be described with reference to Figures 1 to 4. This refrigerator 1 is a device that is driven using a refrigeration cycle.

[0011] (Refrigeration unit) The refrigerator 1 comprises a refrigerator unit 10 and a lubrication system 20. The lubrication system 20 is a device for supplying or recovering refrigerant oil as lubricant to the turbo compressor 11 (compressor) included in the refrigerator unit 10.

[0012] (Refrigeration unit) The refrigerator unit 10 includes a turbo compressor 11, a condenser 12, cooling heat transfer tubes 13, a subcooler 14, a high-pressure expansion valve 15, an intermediate cooler 16, a low-pressure expansion valve 17, an evaporator 18, chilled water heat transfer tubes 19, a first pipe 31, a connecting pipe 32, a second pipe 33, an intermediate pipe 34, a third pipe 35, a fourth pipe 36, a bypass pipe 37, and a bypass valve 38.

[0013] The turbo compressor 11 is a two-stage compressor that compresses refrigerant gas. The turbo compressor 11 has a first-stage low-pressure compression section 41, a second-stage high-pressure compression section 42, and an electric motor 43. When the electric motor 43 is rotationally driven, the low-pressure compression section 41 and the high-pressure compression section 42 rotate coaxially, compressing the refrigerant gas. In the following description, the direction in which the refrigerant flows will be simply called the "flow direction," the side from which the refrigerant flows away will be called the "downstream side," and the opposite side will be called the "upstream side."

[0014] A condenser 12 is connected to the discharge side of the high-pressure compression section 42 via a first pipe 31. Cooling heat transfer tubes 13 through which cooling water flows are laid inside the condenser 12. Heat exchange occurs between this cooling water and the high-temperature, high-pressure refrigerant gas in the condenser 12. A subcooler 14 is connected to the condenser 12 via a connecting pipe 32.

[0015] The subcooler 14 provides supercooling to the liquid refrigerant condensed by heat exchange in the condenser 12. The cooling heat transfer tubes 13 are also located inside the subcooler 14. The cooling water flowing through the cooling heat transfer tubes 13 is supplied from a cooling tower (not shown). After cooling the refrigerant, the cooling water is returned to the cooling tower and released into the atmosphere. After heat release, the cooling water is returned to the refrigerator body 10 and flows through the cooling heat transfer tubes 13 again.

[0016] An intercooler 16 is connected to the downstream side of the subcooler 14 via a second pipe. A high-pressure expansion valve 15 is arranged on the second pipe. The high-pressure expansion valve 15 reduces the pressure of the liquid refrigerant flowing from the subcooler 14. The intercooler 16 cools the refrigerant at intermediate pressure that has been depressurized by the high-pressure expansion valve 15. The refrigerant is separated into a gas phase and a liquid phase in the intercooler 16, and the gas-phase refrigerant is supplied to the intermediate pressure part of the turbo compressor 11 (the suction side of the high-pressure compression part 42) through an intermediate pipe 34. When the liquid-phase refrigerant flows out of the intercooler 16, it heads toward the evaporator 18 connected via the third pipe 35. A low-pressure expansion valve 17 is provided on the third pipe 35, and the liquid-phase refrigerant is further depressurized by the low-pressure expansion valve 17.

[0017] The evaporator 18 evaporates the liquid refrigerant that has been depressurized by the low-pressure expansion valve 17. A cold water heat transfer tube 19 is inserted through the evaporator 18. The cold water flowing through the cold water heat transfer tube 19 is cooled by absorbing vaporization heat when the refrigerant evaporates. The cooled cold water is supplied to an external load (not shown). The refrigerant that has passed through the evaporator 18 is returned to the low-pressure compression part 41 of the turbo compressor 11 through the fourth pipe 36. By the above cycle continuing, the refrigerator main body 10 is operated.

[0018] The bypass pipe 37 is provided between the gas phase part of the condenser 12 and the gas phase part of the evaporator 18 to bypass the refrigerant gas. The bypass valve 38 controls the flow rate of the refrigerant flowing in the bypass pipe 37. By adjusting the bypass flow rate, the flow rate of the refrigerant sucked by the compressor changes according to the load.

[0019] (Oil Supply System) The oil supply system 20 has an oil tank 51, an oil cooler 52, an oil supply pipe 53, a first oil return pipe 54, a second oil return pipe 55, a refrigerant supply pipe 56, a refrigerant return pipe 57, and a pressure equalizing pipe 58.

[0020] The oil tank 51 is a container that stores refrigerating machine oil serving as lubricating oil. Although the detailed configuration of the oil tank 51 will be described later, the oil tank 51 incorporates an oil pump 62. By driving the oil pump 62, supply and recovery of the refrigerating machine oil are performed between the respective parts of the refrigerating machine main body 10.

[0021] An oil cooler 52 is connected to the downstream side of the oil tank 51. The refrigerating machine oil delivered from the oil tank 51 is cooled by the oil cooler 52. A refrigerant supply pipe 56 extending from the condenser 12 is connected to the oil cooler 52, and the refrigerating machine oil is cooled by performing heat exchange between this refrigerant and the refrigerating machine oil. The refrigerant that has risen in temperature due to being used for cooling is returned to the evaporator 18 through a refrigerant return pipe 57.

[0022] After being cooled by the oil cooler 52, the refrigerating machine oil is supplied to the turbo compressor 11 through an oil supply pipe 53. The refrigerating machine oil that has been used to lubricate the movable parts in the turbo compressor 11 is returned to the oil tank 51 through a first oil return pipe 54.

[0023] Here, a part of the refrigerant dissolves into the refrigerating machine oil when passing through the compressor. Accordingly, a part of the refrigerating machine oil flows into each device of the refrigerating machine main body 10 along with the flow of the refrigerant. The refrigerating machine oil accumulated in the condenser 12 and the evaporator 18 is recovered by a second oil return pipe 55 and returned to the oil cooler 52.

[0024] More specifically, the pressure inside the oil tank 51 is maintained at the same low pressure as the suction side of the turbo compressor 11. The second oil return pipe 55 is provided with an ejector (not illustrated) that is driven by high-pressure refrigerant gas flowing from the condenser 12. Due to the pressure difference between the condenser 12 and the oil tank 51, the refrigerating machine oil collected in the evaporator 18 is recovered into the oil tank 51.

[0025] A pressure equalizing pipe 58 connects the oil tank 51 and the evaporator 18, and the pressure equalizing pipe 58 keeps the pressure inside the oil tank 51 and the pressure inside the evaporator 18 uniform.

[0026] (Detailed Configuration of Oil Tank 51) Next, the detailed configuration of the oil tank 51 will be described with reference to Figures 2 to 4. As shown in Figure 2 or Figure 3, the oil tank 51 includes a lower tank 61, an oil pump 62, and an upper tank 63.

[0027] The lower tank 61 has a bottomed cylindrical shape centered on a first axis X1 that extends in the vertical direction. Specifically, the lower tank 61 has a cylindrical lower cylindrical portion 71 centered on the first axis X1 and a bottom portion 72 that closes the opening below the lower cylindrical portion 71. The space inside the lower tank 61 forms a lower space V1 capable of storing refrigeration oil. The bottom portion 72 has a disc shape that extends in a plane perpendicular to the first axis X1.

[0028] An oil pump 62 is inserted into the lower cylindrical portion 71 from the radially outer side with respect to the first axis X1. In other words, the oil pump 62 is rod-shaped with a third axis X3 extending radially as its center. As shown in Figure 3, the tip portion 81 of the oil pump 62 protrudes into the lower space V1 and is capable of drawing in refrigerant oil. The base portion 82 of the oil pump 62 (i.e., the portion exposed to the outside of the lower tank 61) is connected to the aforementioned oil supply pipe 53. Refrigerant oil is supplied to the turbo compressor 11 through this oil supply pipe 53.

[0029] The upper tank 63 is located at the upper end of the lower tank 61. The upper tank 63 has a bottomed cylindrical shape centered on a second axis X2 that extends horizontally and intersects (orthogonal to) the first axis X1 described above.

[0030] More specifically, the upper tank 63 has an upper cylindrical portion 91 centered on the second axis X2, and a pair of lid portions 92 that close the openings on both sides of the upper cylindrical portion 91. The space inside the upper tank 63 forms an upper space V2. The upper space V2 is connected to the entire upper end of the lower space V1. That is, these two spaces form the internal space of the oil tank 51. The pair of lid portions 92 each have a disc shape that extends in a plane perpendicular to the second axis X2. A pressure equalization pipe connection port 101 is provided on one of the lid portions 92. It is desirable that the pressure equalization pipe connection port 101 be located above the second axis X2.

[0031] Furthermore, the outer circumferential surface of the upper cylindrical portion 91 is provided with a first connection port 102 to which the first oil return pipe 54 described above is connected, and a second connection port 103 to which the second oil return pipe 55 is connected. These first connection port 102 and second connection port 103 extend radially with respect to the second axis X2 and are provided at intervals in the direction of the second axis X2 in a region above the second axis X2.

[0032] The upper tank 63 protrudes equally on both sides in the direction of the second axis X2 (horizontal direction), relative to the upper end of the lower tank 61. In other words, the upper tank 63 and the lower tank 61 form a T-shaped outer form. The second axis X2 of the upper tank 63 is located on the first axis X1 of the lower tank 61. Also, as an example, the outer diameter and inner diameter dimensions of the upper tank 63 and the lower tank 61 are the same.

[0033] Furthermore, the terms "vertical direction," "horizontal direction," "same," and "equal" used herein refer to actual vertical, horizontal, same, and equal dimensions, and errors during manufacturing or equipment installation are permitted.

[0034] When the amount of refrigerant oil stored in the lower space V1 described above is taken as 1, it is desirable that the sum of the volumes of the lower space V1 and the upper space V2 be between 3 and 9. More preferably, this sum is between 4 and 7. Most preferably, this sum is between 4.3 and 5. The "amount of refrigerant oil stored" mentioned above refers to the initial amount supplied to the oil tank 51 before the start of operation of the refrigeration unit 1. Therefore, after the start of operation of the refrigeration unit 1, this stored amount may fluctuate slightly (mainly decrease).

[0035] (Effects and Benefits) Here, the refrigerant used in the refrigeration cycle is dissolved in the refrigeration oil. Therefore, if the pressure in the oil tank 51 drops sharply, for example when the turbo compressor 11 is stopped, the refrigerant may gasify. When this happens, the gasified refrigerant foams up inside the tank. This foam can cause the oil pump 62 to experience cavitation or run dry, leading to a decrease in the oil supply pressure. To solve this problem, the oil tank 51 according to this embodiment employs the above-described configurations.

[0036] According to the above configuration, an upper tank 63 is provided at the upper end of the lower tank 61 that stores the refrigeration oil. Furthermore, this upper tank 63 protrudes horizontally on both sides with respect to the upper end of the lower tank 61. That is, compared to the case where the lower tank 61 and the upper tank 63 are formed in a continuous cylindrical shape, the volume of the upper tank 63 is relatively larger. Therefore, even if the refrigeration oil foams, the foaming component F, mainly foam, expands and escapes to the upper tank 63 side (see Figure 4). Consequently, the amount of foam in the lower tank 61 is reduced, and when the oil pump 62 draws out the refrigeration oil, cavitation and dry running of the oil pump 62 due to the entrainment of foam can be avoided. This makes it possible to stably maintain the oil pressure supplying the refrigeration oil. As a result, the machinery to which the oil tank 51 is applied can be operated more stably for an even longer period of time.

[0037] According to the above configuration, the upper tank 63 protrudes equally on both sides in the horizontal direction. This allows the oil pump 62 to draw out the refrigerant oil evenly from both protruding parts of the upper tank 63, even when the liquid level of the refrigerant oil reaches the upper tank 63. In other words, the possibility of unevenness or stagnation in the flow of refrigerant oil from the liquid level to the oil pump 62 is greatly reduced. As a result, the oil supply pressure of the oil pump 62 can be maintained more stably.

[0038] According to the above configuration, both the upper tank 63 and the lower tank 61 are cylindrical in shape with a bottom 72. Therefore, compared to, for example, if they were formed in a rectangular cylindrical shape, dead water areas are less likely to form. Consequently, it is possible to extract all of the refrigerant oil from the entire area of ​​the lower space V1 and the upper space V2 using the oil pump 62. As a result, the loss of refrigerant oil can be reduced, and the oil tank 51 and the machinery to which it is applied can be operated continuously without frequent refueling.

[0039] On the other hand, in the case of the rectangular cylindrical shape described above, dead zones may form inside the corners and other areas. Since the refrigerant oil in these dead zones tends to stagnate without flowing, it does not contribute to maintaining the flow rate of the refrigerant oil throughout the entire machine. As a result, there is a possibility of refrigerant oil loss. However, with the above configuration, such dead zones are less likely to form, thus significantly reducing the possibility of the above-mentioned loss.

[0040] Furthermore, as described above, since the upper tank 63 and the lower tank 61 are cylindrical and form a T-shape overall, the external shape of the oil tank 51 can be constructed simply by combining off-the-shelf tee fittings and straight pipes. This reduces the manufacturing cost and parts procurement cost of the oil tank 51, making it possible to keep the price of the final product low.

[0041] With the above configuration, the sum of the volumes of the lower space V1 and the upper space V2 is between 3 and 9 times the storage capacity of the refrigerant oil. When foaming occurs, the volume of the foam increases significantly compared to that of a liquid. With the above configuration, such foam can be released with ample space, mainly into the upper space V2. Therefore, the possibility of foam filling the oil tank 51 is avoided, and the risk of cavitation or dry running of the oil pump 62 is further reduced.

[0042] According to the above configuration, the pressure equalization pipe connection port 101 is formed on the upper tank 63 side. In other words, the pressure equalization pipe connection port 101 is positioned at a location above the liquid level of the refrigerant oil in the lower tank 61. Therefore, even if the liquid level of the refrigerant oil rises, it becomes difficult for the refrigerant oil to reach the pressure equalization pipe 58 side, reducing the possibility of backflow into external equipment. As a result, it becomes possible to continue operating the machinery to which the oil tank 51 is applied in a more stable manner.

[0043] With the above configuration, since the oil tank 51 is provided, the hydraulic pressure supplying the refrigeration oil can be stably maintained even when foaming occurs. Therefore, it becomes possible to continue operating the refrigeration unit 1 even more stably.

[0044] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure.

[0045] For example, in the above embodiment, an example was described in which the protruding dimensions on both sides of the upper tank 63 in the direction of the second axis X2 are equal to each other. However, the protruding lengths of the upper tank 63 do not necessarily have to be equal.

[0046] Furthermore, the inner diameter of the upper tank 63 may be larger than the inner diameter of the lower tank 61. Conversely, the inner diameter of the lower tank 61 may be larger than the inner diameter of the upper tank 63. Also, the second axis X2 of the upper tank 63 may be slightly offset from the first axis X1 of the lower tank 61.

[0047] Furthermore, the direction in which the oil pump 62 inserted into the lower tank 61 extends can be arbitrarily changed as long as it is in the radial direction perpendicular to the first axis X1.

[0048] In addition, the lower tank 61 and the upper tank 63 do not necessarily have to be cylindrical in shape, and their shapes can be appropriately changed according to the design and specifications.

[0049] In addition, the oil tank 51 according to the above embodiment can be applied to air conditioning equipment other than the refrigerator 1 shown in Figure 1.

[0050] <Note> The oil tank 51 and the refrigerator 1 described in each embodiment can be understood, for example, as follows.

[0051] (1) The oil tank 51 according to the first embodiment comprises a lower tank 61 that extends vertically and has a lower space V1 inside which refrigeration oil can be stored, an upper tank 63 provided at the upper end of the lower tank 61 that extends horizontally and has an upper space V2 inside which is connected to the lower space V1, and an oil pump 62 provided in the lower space V1 that can pump the refrigeration oil to the outside, wherein the upper tank 63 protrudes on both sides in the horizontal direction with respect to the upper end.

[0052] With the above configuration, even if the refrigerant oil foams, cavitation and dry running of the oil pump 62 due to the entrainment of foam can be avoided.

[0053] (2) The oil tank 51 according to the second embodiment is the oil tank 51 of (1), wherein the upper tank 63 protrudes by equal dimensions on both sides in the horizontal direction.

[0054] With the above configuration, the possibility of unevenness or stagnation in the flow of refrigerant oil from the liquid surface toward the oil pump 62 can be greatly reduced.

[0055] (3) The oil tank 51 according to the third embodiment is the oil tank 51 of (1) or (2), wherein the lower tank 61 is a bottomed cylindrical shape centered on the first axis X1 extending in the vertical direction, and the upper tank 63 is a bottomed cylindrical shape centered on the second axis X2 extending in a direction intersecting the first axis X1.

[0056] With the above configuration, it becomes possible to completely extract the refrigerant oil from the entire area of ​​the lower space V1 and the upper space V2 using the oil pump 62.

[0057] (4) The oil tank 51 according to the fourth embodiment is an oil tank 51 according to any one embodiment of (1) to (3), wherein when the amount of refrigerant oil stored in the lower space V1 is set to 1, the sum of the volumes of the lower space V1 and the upper space V2 is 3 or more and 9 or less.

[0058] With the above configuration, the foam can be released with ample space, primarily into the upper space V2.

[0059] (5) The oil tank 51 according to the fifth embodiment is an oil tank 51 according to any one embodiment of (1) to (4), further comprising a pressure equalization pipe connection port 101 formed in the upper tank 63 to which a pressure equalization pipe 58 is connected.

[0060] With the above configuration, even if the liquid level of the refrigeration oil rises, it becomes more difficult for the refrigeration oil to reach the pressure equalizing pipe 58, thereby reducing the possibility of it flowing back into external equipment.

[0061] (6) The refrigerator 1 according to the sixth embodiment comprises a compressor for compressing a refrigerant and an oil tank 51 according to any one of claims 1 to 5 that can supply the refrigerant oil to the compressor.

[0062] With the above configuration, it becomes possible to continue operating the refrigerator 1 in a more stable manner. [Explanation of Symbols]

[0063] 1…Refrigeration unit 10…Refrigeration unit 11… Turbo compressor 12... Condenser 13…Cooling heat transfer tubes 14…Sub-cooler 15…High-pressure expansion valve 16…Intercooler 17... Low-pressure expansion valve 18… Evaporator 19…Chilled water heat transfer tubes 20…Fueling system 31...First piping 32…Connecting pipes 33...Second piping 34…Intermediate piping 35...Third pipe 36…Fourth pipe 37... Bypass pipe 38…Bypass valve 41... Low-pressure compression section 42... High-pressure compression section 43… Electric motor 51… Oil tank 52...Oil cooler 53…Fuel supply piping 54…First oil return piping 55...Second oil return pipe 56…Refrigerant supply piping 57... Refrigerant return piping 58...Pressure equalization pipe 61... Lower tank 62… Oil pump 63… Upper tank 71...Lower cylindrical section 72...bottom 81...Tip 82...Proximal end 91... Upper cylindrical section 92...Lid part 101... Pressure equalization pipe connection port 102...First connection port 103...Second connection port F... Foaming ingredient V1…Lower Space V2…Upper Space X1…Axis 1 X2…Second axis X3… Third axis

Claims

1. A lower tank that extends vertically and has a lower space formed inside in which refrigerant oil can be stored, An upper tank provided at the upper end of the lower tank, extending horizontally and having an upper space formed inside that is connected to the lower space, An oil pump is provided in the lower space and is capable of pressurizing the refrigeration oil to the outside, Equipped with, The upper tank is an oil tank that protrudes horizontally on both sides with respect to the upper end.

2. The oil tank according to claim 1, wherein the upper tank protrudes by equal dimensions on both sides in the horizontal direction.

3. The oil tank according to claim 1 or 2, wherein the lower tank is a bottomed cylindrical shape centered on a first axis extending in the vertical direction, and the upper tank is a bottomed cylindrical shape centered on a second axis extending in a direction intersecting the first axis.

4. The oil tank according to claim 1 or 2, wherein when the amount of refrigerant oil stored in the lower space is set to 1, the sum of the volumes of the lower space and the upper space is 3 or more and 9 or less.

5. The oil tank according to claim 1 or 2, further comprising a pressure equalization pipe connection port formed in the upper tank to which a pressure equalization pipe is connected.

6. A compressor that compresses the refrigerant, An oil tank according to claim 1 or 2 that can supply the refrigeration oil to the compressor, A refrigerator equipped with a refrigerator.

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