Oil way system, cascade unit, energy-saving equipment, refrigeration equipment and control method

Abstract

The invention relates to an oil way system, a cascade unit, energy-saving equipment, refrigeration equipment and a control method, the oil way system comprises a first heat exchanger, a first oil tank and a second oil tank, a first channel and a second channel are arranged in the first heat exchanger, and heat exchange can be conducted between the first channel and the second channel; two ends of the first oil tank are respectively communicated with the first channel to form a first circulating oil path; the two ends of the second oil tank communicate with the second channel to form a second circulating oil way. According to the oil way system, when the oil temperature in the first oil tank and the oil temperature in the second oil tank have a large temperature difference, the oil temperature of one oil tank is too low, and the oil temperature of the other oil tank is too high or too high, heat exchange between the two circulating oil ways can be achieved through the first heat exchanger; and therefore, the conditions of too low oil temperature and too high oil temperature are relieved synchronously, and normal operation of an oil way can be guaranteed. No extra heating assembly or oil cooling assembly is needed, and the power consumption and the manufacturing cost of the oil way system can be obviously reduced.

Description

Technical Field

[0001] The present application relates to the field of lubrication technology, and in particular to an oil circuit system, a cascade unit, an energy-saving device, a refrigeration device and a control method. Background Art

[0002] Since lubricating oil can significantly reduce the friction between two relatively moving parts, it can reduce wear and can also carry away the heat generated during the friction process through the flow of oil, thereby cooling the equipment and preventing the equipment from overheating.

[0003] In order to achieve lubrication of multiple relative friction parts, the prior art usually uses multiple independent oil circuits to achieve targeted lubrication. However, due to the different relative motion conditions of different friction parts, the heat generated is also quite different, which leads to a large temperature difference between multiple independent oil circuits. When the oil temperature is too low or overheated, it will cause lubrication abnormalities. Since multiple oil circuits are independent of each other, heat cannot be transferred and neutralized. It is necessary to set a corresponding heating component and oil cooling component for each oil circuit, which increases the overall cost of the equipment lubrication system.

[0004] Taking the oil circuit in the cascade unit as an example, the cascade unit includes a high-temperature refrigeration system and a low-temperature refrigeration system. When the low-temperature refrigeration system is turned on, the oil temperature of the low-temperature lubrication system is low, the oil viscosity is high, and the fluidity of the lubricating oil is poor, which will cause the low-temperature compressor lubrication system to be abnormal; and the compressor in the high-temperature refrigeration system generates more heat during operation, which will cause the temperature of the high-temperature lubrication oil circuit to rise faster and the oil temperature to be higher, which will lead to a decrease in oil viscosity and poor lubricating effect of the lubricating oil, which will cause the high-temperature compressor lubrication system to be abnormal. Summary of the invention

[0005] The present application provides an oil circuit system, a cascade unit, an energy-saving device, a refrigeration device and a control method to solve the technical problem in the prior art that when multiple oil circuits are independent of each other, a large temperature difference is easily generated due to the different heat in the lubrication area, which easily causes the oil temperature in multiple oil circuits to be too low or overheated.

[0006] In a first aspect, the present application provides an oil circuit system, comprising:

[0007] A first heat exchanger, wherein a first channel and a second channel are provided inside the first heat exchanger, and heat exchange can be performed between the first channel and the second channel;

[0008] A first oil tank, wherein both ends of the first oil tank are respectively connected to the first channel to form a first circulating oil circuit;

[0009] The second oil tank has two ends which are respectively connected with the second passage to form a second oil circulation circuit.

[0010] Optionally, temperature detection components are provided in both the first oil tank and the second oil tank, and valve components are provided in the first circulating oil circuit and the second circulating oil circuit respectively. When the difference between the oil temperature in the first oil tank and the oil temperature in the second oil tank is greater than a preset temperature difference threshold, the valve component opens.

[0011] Optionally, the oil circuit system further includes a second heat exchanger, and both ends of the first oil tank are respectively connected to the second heat exchanger to form a third circulating oil circuit.

[0012] Optionally, the first heat exchanger and the second heat exchanger are arranged in parallel at both ends of the first oil tank;

[0013] Alternatively, the first heat exchanger and the second heat exchanger are arranged in series.

[0014] Optionally, the second heat exchanger is a flash heat exchanger provided with a heat exchange tube group.

[0015] Optionally, a valve is provided on the third circulation oil circuit.

[0016] In a second aspect, the present application provides a cascade unit, including the oil circuit system provided in the first aspect of the present application, and also including a high-temperature refrigeration system, a low-temperature refrigeration system and an intermediate heat exchanger, wherein the intermediate heat exchanger has a third channel and a fourth channel inside, the third channel is connected to the high-temperature refrigeration system to form a first refrigerant circulation loop, and the fourth channel is connected to the low-temperature refrigeration system to form a second refrigerant circulation loop;

[0017] Both ends of the first oil tank are respectively connected to the high-temperature refrigeration system to form a fourth circulation oil circuit, and both ends of the second oil tank are respectively connected to the low-temperature refrigeration system to form a fifth circulation oil circuit.

[0018] Optionally, the high temperature refrigeration system comprises a first compressor and a high temperature condenser, a first exhaust line of the first compressor is in communication with the high temperature condenser, and a first oil separation assembly is provided inside the high temperature condenser;

[0019] The fourth circulating oil circuit includes a first oil supply pipeline and a first oil return pipeline. The first oil supply pipeline is connected between the first oil tank and the first compressor, and the first oil return pipeline is connected between the first oil separation component and the first oil tank.

[0020] Optionally, the high-temperature refrigeration system also includes a high-temperature flasher, the refrigerant outlet of the high-temperature condenser is connected to the refrigerant inlet of the high-temperature flasher through a first refrigerant inlet pipeline, the high-temperature flasher is connected to a first refrigerant outflow pipeline and a second refrigerant outflow pipeline, the first refrigerant outflow pipeline is connected to the air inlet of the first compressor, the second refrigerant outflow pipeline is connected to the inlet of the third channel, and the outlet of the third channel is connected to the air inlet of the first compressor.

[0021] Optionally, the low temperature refrigeration system includes a second compressor, a second exhaust pipeline of the second compressor is connected to the inlet of the fourth channel, and a second oil separation component connected to the fourth channel is provided inside the intermediate heat exchanger;

[0022] The fifth circulating oil circuit includes a second oil supply pipeline and a second oil return pipeline, the second oil supply pipeline is connected between the second oil tank and the second compressor, and the second oil return pipeline is connected between the second oil separation assembly and the second oil tank.

[0023] Optionally, the low-temperature refrigeration system also includes a low-temperature flasher and a low-temperature evaporator. The outlet of the fourth channel is connected to the refrigerant inlet of the low-temperature flasher through a second refrigerant inlet pipeline. The low-temperature flasher is connected to a third refrigerant outflow pipeline and a fourth refrigerant outflow pipeline. The third refrigerant outflow pipeline is connected to the air inlet of the second compressor, the fourth refrigerant outflow pipeline is connected to the low-temperature evaporator, and the refrigerant outlet of the low-temperature evaporator is connected to the air inlet of the second compressor.

[0024] Optionally, a heat exchange tube group is provided inside the low-temperature flasher, and the heat exchange tube group is connected to the oil circuit of the first oil tank.

[0025] In the third aspect, the present application provides an energy-saving device, including the cascade unit provided in the second aspect of the present application, and also including a first working fluid circulation system and a second working fluid circulation system, the first working fluid circulation system is connected to the high-temperature refrigeration system, and is used to absorb the waste heat of the high-temperature refrigeration system; the second working fluid circulation system is connected to the low-temperature refrigeration system, and is used to transfer the waste heat to the low-temperature refrigeration system.

[0026] In a fourth aspect, the present application further provides a refrigeration device, comprising the cascade unit provided in the second aspect of the present application;

[0027] Alternatively, it includes the energy-saving device provided in the third aspect of this application.

[0028] In a fifth aspect, the present application further provides a control method, which is applied to the oil circuit system provided in the first aspect of the present application, and comprises the following steps:

[0029] Obtaining an actual oil temperature value T1 in the first oil tank and an actual oil temperature value T2 in the second oil tank;

[0030] Based on the comparison between the actual oil temperature value and the preset oil temperature threshold, it is determined whether to enter the oil heat exchange mode.

[0031] Optionally, the preset oil temperature threshold includes a first oil temperature threshold Y1 and a second oil temperature threshold Y2, and Y1>Y2;

[0032] If T1>Y2>T2, the first circulation oil circuit and the second circulation oil circuit are opened to enter the oil heat exchange mode;

[0033] If T1≥Y1 and T2≥Y2, the third oil circulation circuit is opened and the oil cooling mode is entered.

[0034] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0035] The oil circuit system provided in the embodiment of the present application connects the first channel of the first heat exchanger with the first oil tank through the first circulating oil circuit, and connects the second channel of the first heat exchanger with the second oil tank through the second circulating oil circuit. When there is a large temperature difference between the oil temperatures in the first oil tank and the second oil tank, and one of them has a low oil temperature and the other has an overheated or high oil temperature, the first heat exchanger can be used to achieve heat exchange between the mutually independent first circulating oil circuit and the second circulating oil circuit, thereby simultaneously achieving the relief of the low oil temperature and overheated oil temperature, and ensuring the normal operation of the oil circuit. There is no need to increase the temperature of the oil tank with too low oil temperature through an additional heating component, and there is no need to cool the oil in the oil tank with overheated oil temperature through an additional oil cooling component, which can significantly reduce the power consumption and manufacturing cost of the oil circuit system.

[0036] The cascade unit, energy-saving equipment, refrigeration equipment and control method provided in the embodiments of the present application include or are applied to the above-mentioned oil circuit system, and can realize oil heat exchange between two oil tanks through the oil circuit system. Therefore, it naturally has the same technical effect as the above-mentioned oil circuit system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0039] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0040] Figure 1 A schematic diagram of an energy-saving device provided in an embodiment of the present application;

[0041] Figure 2 Schematic diagram of the connection of the oil circuit system provided in the embodiment of the present application Figure 1 ;

[0042] Figure 3 A schematic diagram of the state of the oil circuit system provided in the embodiment of the present application in the oil heat exchange mode;

[0043] Figure 4 Schematic diagram of the oil circuit system provided in the embodiment of the present application in the oil cooling mode Figure 1 ;

[0044] Figure 5 Schematic diagram of the connection of the oil circuit system provided in the embodiment of the present application Figure 2 ;

[0045] Figure 6 Schematic diagram of the oil circuit system provided in the embodiment of the present application in the oil cooling mode Figure 2 ;

[0046] Figure 7 A schematic diagram of the connection between the high-temperature refrigeration system, the oil circuit system and the first working fluid circulation system provided in an embodiment of the present application;

[0047] Figure 8 A schematic diagram of the connection between the low-temperature refrigeration system, the oil circuit system and the second working fluid circulation system provided in the embodiment of the present application;

[0048] Fig. 9 The process of the control method provided in the embodiment of the present application Figure 1 ;

[0049] Fig.10 The process of the control method provided in the embodiment of the present application Figure 2 .

[0050] Description of reference numerals:

[0051] 1. Oil circuit system; 11. First heat exchanger; 12. First oil tank; 13. First circulating oil circuit; 131. First output oil circuit; 132. First input oil circuit; 133. First valve member; 14. Second oil tank; 15. Second circulating oil circuit; 151. Second output oil circuit; 152. Second input oil circuit; 153. Second valve member; 16. Third circulating oil circuit; 161. Third output oil circuit; 162. Third input oil circuit; 163. Third valve member; 164. Fourth valve member; 165. Oil pump; 17. Fourth circulating oil circuit; 171. First oil supply pipeline; 172. First oil return pipeline; 18. Fifth circulating oil circuit; 181. Second oil supply pipeline; 182. Second oil return pipeline;

[0052] 2. High-temperature refrigeration system; 21. First refrigerant circulation loop; 211. First exhaust pipeline; 212. First refrigerant inlet pipeline; 213. First refrigerant outlet pipeline; 214. Second refrigerant outlet pipeline; 215. First air inlet pipeline; 216. First throttling device; 217. Second throttling device; 22. First compressor; 23. High-temperature condenser; 24. High-temperature flasher; 25. First filter dryer;

[0053] 3. Low-temperature refrigeration system; 31. Second refrigerant circulation loop; 311. Second exhaust pipeline; 312. Second refrigerant inlet pipeline; 313. Third refrigerant outlet pipeline; 314. Fourth refrigerant outlet pipeline; 315. Second air inlet pipeline; 316. Third throttling element; 317. Fourth throttling element; 32. Second compressor; 33. Low-temperature flasher; 34. Low-temperature evaporator; 35. Second drying filter;

[0054] 4. Intermediate heat exchanger. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0056] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0057] For ease of description, spatial relative terms may be used herein to describe the relative positional relationship or movement of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", "front", "back", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure undergoes a position flip or a posture change or a motion state change, then these directional indications also change accordingly, for example: an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatial relative descriptors used herein are interpreted accordingly.

[0058] In order to solve the technical problem in the prior art that when multiple oil circuits are independent of each other, a large temperature difference is easily generated due to different heat in the lubrication area, which easily causes the oil temperature of multiple oil circuits to be too low or overheated. The present application provides an oil circuit system 1, a cascade unit, an energy-saving device, a refrigeration device and a control method. The oil circuit system 1 can realize heat exchange between two circulating oil circuits through a first heat exchanger 11. When there is a large temperature difference between two independent oil circuits, the temperature difference between the two oil circuits can be reduced through heat exchange, thereby avoiding the situation where the temperature of the two oil circuits is too low or overheated, and the normal operation of the oil circuit can be guaranteed.

[0059] See also Figures 1 to 10 In a first aspect, an embodiment of the present application provides an oil circuit system 1, comprising a first heat exchanger 11, a first oil tank 12, and a second oil tank 14. A first channel and a second channel are provided inside the first heat exchanger 11, and heat exchange can be performed between the first channel and the second channel. Specifically, the first heat exchanger 11 can be a plate heat exchanger, a shell and tube heat exchanger, etc., and the first channel and the second channel can be mutually entangled or nested, etc., which can achieve the purpose of the present application.

[0060] See also Figure 1 and Figure 2The two ends of the first oil tank 12 are respectively connected to the first channel to form a first circulating oil circuit 13. The oil in the first oil tank 12 enters the first channel for heat exchange and then flows back to the first oil tank 12, so that the temperature of the oil in the first circulating oil circuit 13 and the first oil tank 12 can be changed. The two ends of the second oil tank 14 are respectively connected to the second channel to form a second circulating oil circuit 15. The oil in the second oil tank 14 enters the second channel for heat exchange and then flows back to the second oil tank 14, so that the temperature of the oil in the second circulating oil circuit 15 and the second oil tank 14 can be changed. When there is a large temperature difference between the oil temperatures in the first oil tank 12 and the second oil tank 14, and one of them has a low oil temperature and the other has an overheated oil temperature, the first heat exchanger 11 can be used to achieve heat exchange between the two circulating oil circuits, thereby simultaneously alleviating the low oil temperature and overheated oil temperature conditions. There is no need to increase the temperature of the oil tank with a low oil temperature through an additional heating component, and there is no need to cool the oil in the oil tank with an overheated oil temperature through an additional oil cooling component, which can significantly reduce the power consumption and manufacturing cost of the oil circuit system 1.

[0061] It should be noted that when the oil temperature in one of the first oil tank 12 and the second oil tank 14 is too low, and the oil temperature in the other is only relatively high (i.e., it has not reached the overheating state), heat exchange between the two circulating oil circuits can still be achieved through the first heat exchanger 11. While preventing the oil temperature in one of the oil tanks from being too low, the oil in the other oil tank can be cooled to improve the cooling capacity of the cooled oil.

[0062] In some embodiments of this application, please refer to Figure 1 , Figure 2 and Figure 5 The arrows in the figure indicate the flow direction of the oil. In the first heat exchanger 11, the flow directions of the oil in the first channel and the oil in the second channel are opposite. By means of countercurrent heat exchange, the heat exchange path of the two oils at different temperatures inside the first heat exchanger 11 is extended, and the heat exchange efficiency of the hot oil and the cold oil in the first heat exchanger 11 can be improved, so that the temperature distribution inside the first heat exchanger 11 is relatively uniform, which helps to reduce the thermal stress caused by the temperature gradient and improve the stability and life of the first heat exchanger 11.

[0063] In some embodiments of this application, please refer to Figure 1 , Figure 2 , Figure 3 and Figure 5The first circulating oil circuit 13 includes a first output oil circuit 131 and a first input oil circuit 132. The first output oil circuit 131 is used to output the oil in the first oil tank 12 to the first channel of the first heat exchanger 11; the first input oil circuit 132 is used to input the oil in the first channel into the first oil tank 12 to achieve the reflux of the oil after heat exchange. The second circulating oil circuit 15 includes a second output oil circuit 151 and a second input oil circuit 152. The second output oil circuit 151 is used to output the oil in the second oil tank 14 to the second channel of the first heat exchanger 11; the second input oil circuit 152 is used to input the oil in the second channel into the second oil tank 14 to achieve the reflux of the oil after heat exchange.

[0064] In some embodiments of the present application, the first oil tank 12 and the second oil tank 14 are both provided with temperature detection components, and the first circulating oil circuit 13 and the second circulating oil circuit 15 are respectively provided with valve components. When the difference between the oil temperature in the first oil tank 12 and the oil temperature in the second oil tank 14 is greater than a preset threshold value of the temperature difference, the valve components are opened, which can ensure the effectiveness of achieving the neutralization of the oil temperatures of the two oils through heat exchange. Specifically, if the difference between the oil temperatures in the first oil tank 12 and the second oil tank 14 is large, after heat exchange through the first heat exchanger 11, the oil temperatures of the two oils can change significantly (low-temperature oil temperature rises, high-temperature oil temperature drops), which can ensure the effect of avoiding the phenomenon of too low oil temperature and overheating through heat exchange. If the difference in oil temperature between the first oil tank 12 and the second oil tank 14 is small (the oil temperature in both is low or high), then after heat exchange through the first heat exchanger 11, the oil temperatures of both will not change significantly and will still maintain the original oil temperature level, which cannot effectively alleviate the situation where the oil temperature is too low or the oil temperature is overheated.

[0065] It should be noted that the preset temperature difference threshold can be set according to actual conditions. In some preferred embodiments of the present application, the value range of the preset temperature difference threshold is above 20°C.

[0066] In the following embodiments of the present application, the oil temperature in the first oil tank 12 is higher than the oil temperature in the second oil tank 14. When the oil in the second oil tank 14 is too low in temperature and has poor fluidity, the oil in the first oil tank 12 can exchange heat with the oil in the second oil tank 14 through the first heat exchanger 11 due to the higher temperature of the oil in the first oil tank 12, so that the oil flowing back from the first heat exchanger 11 to the first oil tank 12 is cooled, and the oil flowing back from the first heat exchanger 11 to the second oil tank 14 is heated, which is beneficial to ensure the normal operation of the lubrication systems corresponding to the first oil tank 12 and the second oil tank 14.

[0067] It should be noted that during the heat exchange process, the oil in the first oil tank 12 and the second oil tank 14 will not be mixed, and the oil quality in the first oil tank 12 and the second oil tank 14 will not be adversely affected. The first oil tank 12 and the second oil tank 14 can select different brands of lubricating oil according to lubrication needs, which will not affect the normal operation of the lubrication system.

[0068] In the above embodiment, if the oil temperature in the first oil tank 12 is too high, it is still at a relatively high temperature level after heat exchange with the oil in the second oil tank 14; or, the oil temperature in the second oil tank 14 is within the normal operating temperature range and the oil in the first oil tank 12 cannot be cooled by heat exchange, both of which will cause the oil in the first oil tank 12 to be at risk of overheating, and the oil in the first oil tank 12 needs to be further cooled.

[0069] In order to solve the above technical problems, in some embodiments of the present application, please refer to Figure 2 and Figure 5 The oil circuit system 1 also includes a second heat exchanger. Both ends of the first oil tank 12 are respectively connected to the second heat exchanger to form a third circulating oil circuit 16. The oil in the first oil tank 12 can be heat exchanged in the second heat exchanger so that the oil temperature in the first oil tank 12 is within the normal working temperature range.

[0070] Specifically, in the second heat exchanger, other working fluids can be used to exchange heat with the oil in the first oil tank 12, thereby reducing the temperature of the oil in the first oil tank 12 and avoiding the risk of overheating of the oil in the first oil tank 12. The normal operating temperature range of the oil can be set according to the characteristics of the oil, usually between 10°C and 50°C, preferably between 15°C and 40°C, which can ensure that the viscosity of the oil is reasonable, the fluidity is good, and the cooling effect of the oil on the lubricated parts is good.

[0071] In some embodiments of this application, please refer to Figure 1 , Figure 2 , Figure 4 , Figure 5 and Figure 6 , the arrow indicates the direction of oil flow, the third circulation oil circuit 16 includes a third output oil circuit 161 and a third input oil circuit 162, the third output oil circuit 161 is used to output the oil in the first oil tank 12 to the heat exchange tube group of the second heat exchanger; the third input oil circuit 162 is used to input the oil in the heat exchange tube group into the first oil tank 12, so as to realize the reflux of the oil after heat exchange.

[0072] In some embodiments of this application, please refer to Figure 2 , Figure 3 and Figure 4, the first heat exchanger 11 and the second heat exchanger are arranged in parallel at both ends of the first oil tank 12. The oil in the first oil tank 12 can enter the first heat exchanger 11 through the first circulating oil circuit 13 to exchange heat with the oil in the second oil tank 14 as needed, which is recorded as the oil heat exchange mode; the oil in the first oil tank 12 can also enter the second heat exchanger through the third circulating oil circuit 16 to be cooled, which is recorded as the oil cooling mode. The oil in the first oil tank 12 can first be cooled for the first time through the oil heat exchange mode, and then cooled for the second time through the oil cooling mode, so that the oil in the first oil tank 12 reaches a fully cooled state and is cooled to the normal operating temperature range. When the temperature of the oil in the second oil tank 14 is within the normal operating temperature range, the first oil tank 12 can directly enter the oil cooling mode, and directly cool the oil in the first oil tank 12 through the second heat exchanger.

[0073] In other embodiments of the present application, please refer to Figure 5 and Figure 6 The first heat exchanger 11 and the second heat exchanger are arranged in series, so that the oil in the first oil tank 12 passes through the first heat exchanger 11 and the second heat exchanger (or passes through the second heat exchanger and the first heat exchanger 11 in sequence), so that the oil heat exchange mode and the oil cooling mode are in parallel. When the oil temperature in the second oil tank 14 is within the normal operating temperature range, the second circulation oil circuit 15 can be closed. At this time, the oil in the first oil tank 12 does not exchange heat with the oil in the second oil tank 14 in the first heat exchanger 11, and the oil in the first oil tank 12 is only cooled by the second heat exchanger, so that the oil cooling mode continues to operate.

[0074] As a specific embodiment of this application, please refer to Figure 5 and Figure 6 When the first heat exchanger 11 is connected in series with the second heat exchanger, the end of the first input oil circuit 132 is connected to the starting end of the third output oil circuit 161, so that the oil in the first oil tank 12 flows through the first heat exchanger 11 and the second heat exchanger in sequence, achieving secondary cooling, thereby reducing the temperature of the high-temperature oil in the first oil tank 12 to a normal working temperature range.

[0075] It should be noted that although the above two connection methods can both achieve cooling of the oil in the first oil tank 12, when the first heat exchanger 11 is connected in series with the second heat exchanger, the oil pipeline will be longer and the resistance of the oil during the flow will be greater. Therefore, in the embodiment of the present application, it is preferred to set the first heat exchanger 11 and the second heat exchanger in parallel.

[0076] In the above embodiment, the second heat exchanger can be any device that needs to absorb and utilize waste heat. By absorbing the heat of the oil in the first oil tank 12, waste heat can be recovered and utilized, thereby improving energy utilization efficiency.

[0077] In some embodiments of this application, please refer to Figure 1 , Figure 2 and Figure 5 The second heat exchanger is a flash unit equipped with a heat exchange tube group. The oil in the first oil tank 12 is passed into the heat exchange tube group as the tube-side working fluid of the flash unit. The refrigerant inside the flash unit is the shell-side working fluid. Heat can be transferred to the shell-side working fluid through the oil in the heat exchange tube group, so that the liquid refrigerant inside the flash unit can be changed from liquid to gas more quickly, thereby improving the air supply effect of the flash unit and improving the air supply superheat of the flash unit, thereby avoiding damage to the compressor when the air supply superheat of the flash unit is low.

[0078] In some embodiments of this application, please refer to Figures 1 to 6 The first oil circulation circuit 13, the second oil circulation circuit 15 and the third oil circulation circuit 16 are all provided with valves, which can be used to realize the on-off control of the first oil circulation circuit 13, the second oil circulation circuit 15 and the third oil circulation circuit 16 respectively, and can enter the oil heat exchange mode and / or the oil cooling mode as needed.

[0079] Specifically, a first valve component 133 is provided on the first output oil circuit 131 and the first input oil circuit 132 of the first circulation oil circuit 13, a second valve component 153 is provided on the second output oil circuit 151 and the second input oil circuit 152 of the second circulation oil circuit 15, and a third valve component 163 is provided on the third output oil circuit 161 and the third input oil circuit 162 of the third circulation oil circuit 16. The above-mentioned valve components can be solenoid valves, electric valves, pneumatic valves and hydraulic valves, etc., all of which can realize automatic on-off control of the oil circuit.

[0080] When the first heat exchanger 11 and the second heat exchanger are arranged in parallel, if the oil circuit system 1 is required to perform the oil heat exchange mode, the first valve member 133 and the second valve member 153 are opened, the first circulation oil circuit 13 and the second circulation oil circuit 15 are opened; the third valve member 163 is closed, and the third circulation oil circuit 16 is closed, so that the first oil tank 12 and the second oil tank 14 can exchange heat through the first heat exchanger 11. If the oil circuit system 1 is required to perform the oil cooling mode, the first valve member 133 and the second valve member 153 are closed, the first circulation oil circuit 13 and the second circulation oil circuit 15 are closed; the third valve member 163 is opened, and the third circulation oil circuit 16 is opened, so that the oil in the first oil tank 12 can be cooled through the second heat exchanger.

[0081] In some embodiments of the present application, a fourth valve component 164 may be further provided on the first circulation oil circuit 13 , the second circulation oil circuit 15 and the third circulation oil circuit 16 . The fourth valve component 164 is a stop valve to facilitate segmented start-stop control and maintenance on each oil circuit.

[0082] In some embodiments of this application, please refer to Figure 1 , Figure 2 , Figure 4 , Figure 5 and Figure 6 The third oil circulation circuit 16 is provided with an oil pump 165, which can provide driving force for the oil flow in the third oil circulation circuit 16. It should be noted that the first oil circulation circuit 13 and the second oil circulation circuit 15 can also be provided with oil pumps to provide power for the oil flow (not shown in the figure), which will not be repeated here.

[0083] In some embodiments of the present application, the first circulating oil circuit 13, the second circulating oil circuit 15 and the third circulating oil circuit 16 are all provided with temperature detection components, which can be used to detect the actual oil temperature at various locations of the oil circuit system 1, thereby realizing intelligent regulation of the oil temperature.

[0084] See also Figures 1 to 10 The second aspect of the embodiment of the present application provides a cascade unit, including the oil circuit system 1 in the above embodiment, and also including a high-temperature refrigeration system 2, a low-temperature refrigeration system 3 and an intermediate heat exchanger 4. The intermediate heat exchanger 4 has a third channel and a fourth channel inside. The third channel is connected with the high-temperature refrigeration system 2 to form a first refrigerant circulation loop 21, and the fourth channel is connected with the low-temperature refrigeration system 3 to form a second refrigerant circulation loop 31. During the operation of the cascade unit, the intermediate heat exchanger 4 is both an evaporator in the high-temperature refrigeration system 2 and a condenser in the low-temperature refrigeration system 3. The high-temperature refrigeration system 2 uses a first refrigerant with a higher evaporation temperature, and the low-temperature refrigeration system 3 uses a second refrigerant with a lower evaporation temperature. The second refrigerant transfers heat to the first refrigerant in the intermediate heat exchanger 4, thereby realizing condensation of the second refrigerant and evaporation of the first refrigerant in the intermediate heat exchanger 4.

[0085] The two ends of the first oil tank 12 are respectively connected to the high-temperature refrigeration system 2 to form a fourth oil circulation circuit 17 for providing lubricating oil to the parts to be lubricated in the high-temperature refrigeration system 2. The two ends of the second oil tank 14 are respectively connected to the low-temperature refrigeration system 3 to form a fifth oil circulation circuit 18 for providing lubricating oil to the parts to be lubricated in the low-temperature refrigeration system 3. Since the cooling capacity of the high-temperature refrigeration system 2 and the low-temperature refrigeration system 3 are different, the friction heat generated during their operation is also different, which will cause a large temperature difference between the oil in the first oil tank 12 and the second oil tank 14. The present application can achieve heat exchange between the oil in the first oil tank 12 and the second oil tank 14 through the oil circuit system 1 in the above embodiment, so that the first oil tank 12 and the second oil tank 14 respectively transport lubricating oil in the normal working temperature range to the high-temperature refrigeration system 2 and the low-temperature refrigeration system 3, such as Figure 1 , Figure 7 and Figure 8 As shown, Figure 1 , Figure 7 and Figure 8 The dotted line pipeline is the oil circuit, and the solid line pipeline is the refrigerant circulation loop.

[0086] It should be noted that, during the operation of the existing cascade unit, the following problems often exist: First, the lubricating oil circuit in the low-temperature refrigeration system 3 has a low oil temperature when it is turned on, the viscosity of the oil is large, and the fluidity of the lubricating oil is poor, which will lead to oil supply difficulties, and then cause the compressor lubrication system in the low-temperature refrigeration system 3 to be abnormal. Second, after the cascade unit has been running for a period of time, the compressor in the high-temperature refrigeration system 2 has a large refrigeration capacity, and the friction heat generated during its operation is also large, which will cause the oil temperature to rise rapidly, the viscosity of the lubricating oil to decrease rapidly, and the lubrication effect is poor, which will cause the compressor lubrication system in the high-temperature refrigeration system 2 to be abnormal. The oil circuit system 1 in the present application can realize the heat exchange of the oil in the first oil tank 12 and the second oil tank 14 through the first heat exchanger 11, which can avoid the oil temperature in the lubricating oil circuit of the compressor in the low-temperature refrigeration system 3 from being too low, and can avoid the oil temperature in the lubricating oil circuit of the compressor in the high-temperature refrigeration system 2 from being too high, thereby ensuring the normal operation of the cascade unit.

[0087] In some embodiments of this application, please refer to Figure 1 and Figure 7 The high-temperature refrigeration system 2 includes a first compressor 22 and a high-temperature condenser 23. The first exhaust line 211 of the first compressor 22 is connected to the high-temperature condenser 23. During the continuous exhaust process of the first compressor 22, the lubricating oil (i.e., refrigeration oil) will be discharged from the first compressor 22 together with the gaseous first refrigerant through the first exhaust line 211. If the discharged refrigeration oil cannot be returned to the first compressor 22, the first compressor 22 will lose oil, and even be damaged in severe cases. For this reason, a first oil separation component is provided inside the high-temperature condenser 23, which can be used to separate the refrigeration oil and the first refrigerant.

[0088] The fourth circulation oil circuit 17 includes a first oil supply pipeline 171 and a first oil return pipeline 172. The first oil supply pipeline 171 is connected between the first oil tank 12 and the first compressor 22, and can continuously provide refrigerant oil to the first compressor 22 through the first oil tank 12. The first oil return pipeline 172 is connected between the first oil separation component and the first oil tank 12, and can return the refrigerant oil separated in the high-temperature condenser 23 to the first oil tank 12, so as to realize the circulation of the refrigerant oil between the first compressor 22 and the first oil tank 12, thereby avoiding the oil loss of the first compressor 22.

[0089] In some embodiments of this application, please refer to Figure 1 and Figure 7The high-temperature refrigeration system 2 also includes a high-temperature flasher 24. The refrigerant outlet of the high-temperature condenser 23 is connected to the refrigerant inlet of the high-temperature flasher 24 through the first refrigerant inlet pipeline 212. The condensed first refrigerant can be input into the high-temperature flasher 24 for rapid evaporation to form saturated gaseous refrigerant and saturated liquid refrigerant. The high-temperature flasher 24 is connected to a first refrigerant outflow pipeline 213 and a second refrigerant outflow pipeline 214. The first refrigerant outflow pipeline 213 is connected to the air inlet of the first compressor 22. The saturated gaseous refrigerant enters the high-pressure stage air inlet of the first compressor 22 from the top of the high-temperature flasher 24, and can be compressed in two stages. The second refrigerant outflow pipeline 214 is connected to the inlet of the third channel, so that the saturated liquid refrigerant flows into the intermediate heat exchanger 4 for heat exchange and evaporation; the outlet of the third channel is connected to the air inlet of the first compressor 22, and the first refrigerant circulation loop 21 includes a first exhaust pipeline 211, a first refrigerant inflow pipeline 212, a first refrigerant outflow pipeline 213 and a second refrigerant outflow pipeline 214, which can complete the refrigerant circulation of the first refrigerant.

[0090] In some embodiments of this application, please refer to Figure 7 The first refrigerant inflow pipe 212 is provided with a first throttling member 216, which can throttle the liquid refrigerant flowing out of the high-temperature condenser, and the throttled first refrigerant flows into the high-temperature flasher 24 for rapid evaporation. The second refrigerant outflow pipe 214 is provided with a second throttling member 217, which can throttle the saturated liquid refrigerant flowing out of the high-temperature flasher 24, so that the saturated liquid refrigerant further undergoes decompression and expansion, becomes a low-pressure, low-temperature liquid, and then enters the intermediate heat exchanger 4 for heat exchange and evaporation.

[0091] In some embodiments of this application, please refer to Figure 1 and Figure 7 A first drying filter 25 is provided on the first refrigerant inflow pipeline 212, which can remove impurities and moisture in the first refrigerant and extend the service life of key components in the high-temperature refrigeration system 2 (such as the first compressor 22, the first throttling device 216, the second throttling device 217, etc.).

[0092] In some embodiments of this application, please refer to Figure 1 and Figure 8The low-temperature refrigeration system 3 includes a second compressor 32, and a second exhaust pipeline 311 of the second compressor 32 is connected to the inlet of the fourth channel. During the continuous exhaust process of the second compressor 32, the refrigerant oil in the second compressor 32 will be discharged from the second compressor 32 together with the gaseous second refrigerant through the second exhaust pipeline 311. If the discharged refrigerant oil cannot be returned to the second compressor 32, the second compressor 32 will lose oil or be damaged. To this end, a second oil separation component connected to the fourth channel is provided inside the intermediate heat exchanger 4 to separate the refrigerant oil from the second refrigerant.

[0093] The fifth circulation oil circuit 18 includes a second oil supply pipeline 181 and a second oil return pipeline 182. The second oil supply pipeline 181 is connected between the second oil tank 14 and the second compressor 32, and can continuously provide refrigerant oil to the second compressor 32 through the second oil tank 14. The second oil return pipeline 182 is connected between the second oil separation component and the second oil tank 14, and can return the refrigerant oil separated in the intermediate heat exchanger 4 to the second oil tank 14, so as to realize the circulation of the refrigerant oil between the second compressor 32 and the second oil tank 14, thereby avoiding the oil loss of the second compressor 32.

[0094] In some embodiments of this application, please refer to Figure 1 and Figure 8 The low-temperature refrigeration system 3 also includes a low-temperature flasher 33 and a low-temperature evaporator 34. The outlet of the fourth channel is connected to the refrigerant inlet of the low-temperature flasher 33 through the second refrigerant inlet pipeline 312. The condensed second refrigerant can be input into the low-temperature flasher 33 for rapid evaporation, thereby forming a saturated gaseous refrigerant and a saturated liquid refrigerant. The low-temperature flasher 33 is connected to a third refrigerant outflow pipeline 313 and a fourth refrigerant outflow pipeline 314. The third refrigerant outflow pipeline 313 is connected to the air inlet of the second compressor 32. The saturated gaseous refrigerant enters the high-pressure stage air inlet of the second compressor 32 from the top of the low-temperature flasher 33, and can be compressed in two stages. The fourth refrigerant outflow pipeline 314 is connected to the low-temperature evaporator 34, so that the saturated liquid refrigerant flows into the low-temperature evaporator 34 for heat exchange and evaporation; the refrigerant outlet of the low-temperature evaporator 34 is connected to the air inlet of the second compressor 32, and the second refrigerant circulation loop 31 includes a second exhaust pipeline 311, a second refrigerant inflow pipeline 312, a third refrigerant outflow pipeline 313 and a fourth refrigerant outflow pipeline 314, which can complete the refrigerant circulation of the second refrigerant.

[0095] In the above embodiment, since the evaporation temperature of the second refrigerant is relatively low, the temperature of the gaseous second refrigerant output by the low-temperature flasher 33 will be lower than the saturation temperature at the pressure, resulting in a low degree of superheat of the replenishing air of the low-temperature flasher 33, which may cause the second refrigerant to liquefy in the second compressor 32 and cause damage to the second compressor 32.

[0096] In order to solve the above problems, in some embodiments of the present application, a heat exchange tube group is provided inside the low-temperature flasher 33, and the heat exchange tube group is connected to the oil circuit of the first oil tank 12, so that the low-temperature flasher 33 can be configured as the second heat exchanger in the oil circuit system 1. While cooling the oil temperature in the first oil tank 12, the temperature of the gaseous second refrigerant input to the second compressor 32 by the low-temperature flasher 33 can be increased, thereby increasing the air supply superheat of the low-temperature flasher 33.

[0097] In some embodiments of the present application, a baffle is further provided in the liquid storage area inside the low-temperature flasher 33, which can, on the one hand, enhance the disturbance of the second refrigerant and enable rapid evaporation; on the other hand, during the air intake process of the second compressor 32, it can also prevent the liquid refrigerant in the low-temperature flasher 33 from being carried into the second compressor 32 during the air flow, which is beneficial to improving the superheat of the low-temperature flasher.

[0098] In some embodiments of this application, please refer to Figure 8 A third throttling device 316 is provided on the second refrigerant inlet pipeline 312; a fourth throttling device 317 is provided on the fourth refrigerant outflow pipeline 314, and a second drying filter 35 is provided on the second refrigerant inlet pipeline 312, which can throttle or dry filter the second refrigerant in the second refrigerant circulation loop 31, and its function is similar to that of the first throttling device 216, the second throttling device 217 and the first drying filter 25, which will not be repeated here.

[0099] In the above embodiment, the first compressor 22 and the second compressor 32 are screw compressors, which can achieve stepless energy regulation, so that the cascade unit can flexibly adjust the cooling capacity according to actual needs during operation, thereby improving the operating efficiency.

[0100] See also Figures 1 to 10 The third aspect of the embodiment of the present application provides an energy-saving device, including the cascade unit in the above embodiment, and also including a first working fluid circulation system and a second working fluid circulation system. The first working fluid circulation system is connected to the high-temperature refrigeration system 2, and is used to absorb the waste heat of the high-temperature refrigeration system 2, and to increase the temperature of the first working fluid in the first working fluid circulation system through the waste heat of the high-temperature refrigeration system 2, thereby realizing the supply of hot fluid. The second working fluid circulation system is connected to the low-temperature refrigeration system 3, and is used to transfer waste heat to the low-temperature refrigeration system 3, and to reduce the temperature of the second working fluid in the second working fluid circulation system, thereby realizing the supply of cold fluid.

[0101] In the above embodiments, the first working fluid and the second working fluid may be water, lubricating oil, refrigerant and other substances, which can achieve efficient energy utilization through heat exchange, thereby reducing energy consumption caused by heating or cooling of the working fluid and achieving energy saving effect.

[0102] As a specific embodiment of the present application, the first working medium circulation system is a cooling water circulation system, and the second working medium circulation system is a chilled water circulation system; wherein the cooling water circulation system exchanges heat with the high temperature refrigeration system 2 through the high temperature condenser 23, can absorb the waste heat of the high temperature refrigeration system 2, and condenses the first refrigerant in the high temperature condenser 23, and the cooling water flowing out of the high temperature condenser 23 can be used as hot water supply. The chilled water circulation system exchanges heat with the low temperature refrigeration system 3 through the low temperature evaporator 34, can transfer waste heat to the low temperature refrigeration system 3, and evaporate the second refrigerant in the low temperature evaporator 34, and the chilled water is cooled inside the low temperature evaporator 34, so that the chilled water flowing out of the low temperature evaporator 34 can be used as a cooling working medium in the cooling circulation system.

[0103] See also Figures 1 to 10 The fourth aspect of the embodiments of the present application provides a refrigeration device, including the cascade unit in the above embodiments, such as an air conditioner and a refrigerator, which can realize zoned cooling (or heating) to meet the temperature requirements of different areas.

[0104] In other embodiments of the present application, the refrigeration equipment includes the energy-saving equipment in the above embodiments, which can realize the synchronous supply of hot fluid and cooling medium while meeting the cooling and heating needs, which is beneficial to reducing the overall energy consumption of the refrigeration equipment.

[0105] See also Figures 1 to 10 The fifth aspect of the embodiment of the present application provides a control method, which is applied to the oil circuit system 1 in the above embodiment, and includes the following steps:

[0106] Step 1: Start the cascade unit;

[0107] Step 2: Obtain the actual oil temperature value T1 in the first oil tank 12 and the actual oil temperature value T2 in the second oil tank 14; determine whether to enter the oil heat exchange mode or the oil cooling mode based on the comparison between the actual oil temperature value and the preset oil temperature threshold.

[0108] When the oil temperature of the compressor refrigeration oil is too low, there will be a problem of poor fluidity, and when the oil temperature is too high, there will be a problem of poor lubrication effect. Therefore, the preset oil temperature thresholds include a first oil temperature threshold Y1 and a second oil temperature threshold Y2, and Y1>Y2; wherein Y1 is the minimum limit of the oil temperature. When the oil temperature is lower than the first oil temperature threshold Y1, the oil fluidity will be poor; Y2 is the maximum limit of the oil temperature. When the oil temperature is higher than the second oil temperature threshold Y2, the oil lubrication effect will be poor.

[0109] As a specific embodiment of the present application, the value of the first oil temperature threshold value Y1 is 10°C, and the value of the second oil temperature threshold value Y2 is 50°C.

[0110] Step three: Determine whether T2 is less than the second oil temperature threshold value Y2, so as to confirm whether there is a risk of poor fluidity in the lubricating oil circuit of the low-temperature refrigeration system 3; if T1>Y2>T2, then open the first valve member 133 and the second valve member 153, open the first circulation oil circuit 13 and the second circulation oil circuit 15, and enter the oil heat exchange mode; since the cooling capacity of the first compressor 22 is greater than the cooling capacity of the second compressor 32, the oil temperature in the first oil tank 12 will rise rapidly. When the first oil tank 12 and the second oil tank 14 are heat exchanged through the first heat exchanger 11, the temperature of the oil in the second oil tank 14 can be increased, so that the oil temperature in the second oil tank 14 is increased to the normal operating temperature range. At the same time, the rising speed of the oil temperature in the first oil tank 12 is also slowed down to avoid the oil temperature in the first oil tank 12 being too high, thereby causing the oil temperature entering the first compressor 22 to be too high.

[0111] It should be noted that, in the initial stage of the cascade unit startup, if the oil temperature in the first oil tank 12 is also low, the oil in the second oil tank 14 may be heated by other heating methods, such as Fig. 9 shown.

[0112] Step 4: After the cascade unit has been running for a period of time, if the oil temperature in the second oil tank 14 reaches T2 ≥ Y2, the first valve member 133 and the second valve member 153 are closed, and the first circulation oil circuit 13 and the second circulation oil circuit 15 are closed.

[0113] Step 5: Please refer to Fig.10 After the cascade unit has been running for a long time, the oil temperature in the first oil tank 12 continues to rise, and the risk of overheating of the oil in the first oil tank 12 cannot be avoided. It is determined whether T1 is greater than the first oil temperature threshold Y1. If T1≥Y1 and T2≥Y2, the third valve member 163 is opened, the third circulation oil circuit 16 is opened, and the oil cooling mode is entered. The oil output from the first oil tank 12 is heat exchanged inside the low-temperature flasher 33 in the cascade unit, so that the oil temperature is transferred to the refrigerant in the low-temperature flasher 33, which can not only realize the cooling of the oil in the first oil tank 12, but also increase the superheat of the replenishing air of the low-temperature flasher 33.

[0114] Step 6: When the oil temperature in the first oil tank 12 drops to the normal operating temperature range, close the third valve 163 and the third oil circulation circuit 16. (If the first heat exchanger 11 and the second heat exchanger are connected in series, the first valve 133 and the first oil circulation circuit 13 also need to be closed).

[0115] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0116] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0117] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. An oil circuit system (1), characterized in that: include: A first heat exchanger (11), wherein a first channel and a second channel are provided inside the first heat exchanger (11), and heat exchange can be performed between the first channel and the second channel; A first oil tank (12), wherein both ends of the first oil tank (12) are respectively connected to the first channel to form a first circulating oil path (13); A second oil tank (14), both ends of which are respectively connected to the second passage to form a second circulating oil path (15).

2. The oil circuit system (1) according to claim 1, characterized in that: The first oil tank (12) and the second oil tank (14) are both provided with temperature detection components, and the first circulating oil circuit (13) and the second circulating oil circuit (15) are respectively provided with valve components, and when the difference between the oil temperature in the first oil tank (12) and the oil temperature in the second oil tank (14) is greater than a preset temperature difference threshold, the valve components are opened.

3. The oil circuit system (1) according to claim 1 or 2, characterized in that: It also includes a second heat exchanger, and both ends of the first oil tank (12) are respectively connected to the second heat exchanger to form a third circulating oil circuit (16).

4. The oil circuit system (1) according to claim 3, characterized in that: The first heat exchanger (11) and the second heat exchanger are arranged in parallel at two ends of the first oil tank (12); Alternatively, the first heat exchanger (11) and the second heat exchanger are arranged in series.

5. The oil circuit system (1) according to claim 3, characterized in that: The second heat exchanger is a flash heat exchanger provided with a heat exchange tube group.

6. The oil circuit system (1) according to claim 3, characterized in that: The third circulating oil circuit (16) is provided with a valve.

7. A cascade unit, characterized in that: The oil circuit system (1) comprises the oil circuit system (1) according to any one of claims 1 to 6, and further comprises a high-temperature refrigeration system (2), a low-temperature refrigeration system (3) and an intermediate heat exchanger (4), wherein the intermediate heat exchanger (4) has a third channel and a fourth channel inside, the third channel is connected to the high-temperature refrigeration system (2) to form a first refrigerant circulation loop (21), and the fourth channel is connected to the low-temperature refrigeration system (3) to form a second refrigerant circulation loop (31); The two ends of the first oil tank (12) are respectively connected to the high-temperature refrigeration system (2) to form a fourth circulation oil circuit (17), and the two ends of the second oil tank (14) are respectively connected to the low-temperature refrigeration system (3) to form a fifth circulation oil circuit (18).

8. The cascade unit according to claim 7, characterized in that: The high-temperature refrigeration system (2) comprises a first compressor (22) and a high-temperature condenser (23); a first exhaust pipe (211) of the first compressor (22) is in communication with the high-temperature condenser (23); and a first oil separation component is provided inside the high-temperature condenser (23); The fourth circulating oil circuit (17) comprises a first oil supply pipeline (171) and a first oil return pipeline (172), wherein the first oil supply pipeline (171) is connected between the first oil tank (12) and the first compressor (22), and the first oil return pipeline (172) is connected between the first oil separation component and the first oil tank (12).

9. The cascade unit according to claim 8, characterized in that: The high-temperature refrigeration system (2) further comprises a high-temperature flasher (24); the refrigerant outlet of the high-temperature condenser (23) is connected to the refrigerant inlet of the high-temperature flasher (24) via a first refrigerant inlet pipeline (212); the high-temperature flasher (24) is connected to a first refrigerant outflow pipeline (213) and a second refrigerant outflow pipeline (214); the first refrigerant outflow pipeline (213) is connected to an air inlet of the first compressor (22); the second refrigerant outflow pipeline (214) is connected to an inlet of the third channel; and the outlet of the third channel is connected to an air inlet of the first compressor (22).

10. The cascade unit according to any one of claims 7 to 9, characterized in that: The low-temperature refrigeration system (3) comprises a second compressor (32), a second exhaust pipeline (311) of the second compressor (32) is connected to the inlet of the fourth channel, and a second oil separation component connected to the fourth channel is provided inside the intermediate heat exchanger (4); The fifth circulating oil circuit (18) comprises a second oil supply pipeline (181) and a second oil return pipeline (182), wherein the second oil supply pipeline (181) is connected between the second oil tank (14) and the second compressor (32), and the second oil return pipeline (182) is connected between the second oil separation assembly and the second oil tank (14).

11. The cascade unit according to claim 10, characterized in that: The low-temperature refrigeration system (3) also includes a low-temperature flasher (33) and a low-temperature evaporator (34); the outlet of the fourth channel is connected to the refrigerant inlet of the low-temperature flasher (33) via a second refrigerant inlet pipeline (312); the low-temperature flasher (33) is connected to a third refrigerant outflow pipeline (313) and a fourth refrigerant outflow pipeline (314); the third refrigerant outflow pipeline (313) is connected to the air inlet of the second compressor (32); the fourth refrigerant outflow pipeline (314) is connected to the low-temperature evaporator (34); and the refrigerant outlet of the low-temperature evaporator (34) is connected to the air inlet of the second compressor (32).

12. The cascade unit according to claim 11, characterized in that: A heat exchange tube group is provided inside the low-temperature flasher (33), and the heat exchange tube group is connected to the oil circuit of the first oil tank (12).

13. An energy-saving device, characterized in that: A cascade unit comprising any one of claims 7 to 12, further comprising a first working fluid circulation system and a second working fluid circulation system, wherein the first working fluid circulation system is connected to the high-temperature refrigeration system (2) and is used to absorb waste heat of the high-temperature refrigeration system (2); The second working medium circulation system is connected to the low-temperature refrigeration system (3) and is used to transfer waste heat to the low-temperature refrigeration system (3).

14. A refrigeration device, characterized in that: Comprising the cascade unit according to any one of claims 7 to 12; Or, comprising the energy saving device as claimed in claim 13.

15. A control method, characterized in that: The oil circuit system (1) as claimed in any one of claims 3 to 7 comprises the following steps: Obtaining an actual oil temperature value T1 in the first oil tank (12) and an actual oil temperature value T2 in the second oil tank (14); Based on the comparison between the actual oil temperature value and the preset oil temperature threshold, it is determined whether to enter the oil heat exchange mode.

16. The control method according to claim 15, characterized in that: The preset oil temperature threshold includes a first oil temperature threshold Y1 and a second oil temperature threshold Y2, and Y1>Y2; If T1>Y2>T2, the first circulation oil circuit (13) and the second circulation oil circuit (15) are opened to enter the oil heat exchange mode; If T1≥Y1 and T2≥Y2, the third oil circulation circuit (16) is opened to enter the oil cooling mode.

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