A chiller unit

Abstract

This application relates to a chiller unit, comprising: a refrigeration circuit, an electric oil supply circuit, and a pneumatic oil supply circuit, wherein the pneumatic oil supply circuit and the electric oil supply circuit are connected in parallel. This application sets the electric and pneumatic oil supply circuits to work together. Under normal conditions, the electric oil supply circuit can stably provide lubricating oil to the compressor, ensuring the lubrication needs during normal operation of the unit. When the electric oil supply circuit malfunctions due to sudden power outages, oil pump failures, or other situations, the control element switches to a second state, using the high-pressure gaseous refrigerant in the condenser to drive the pneumatic oil pump through the pneumatic drive pipeline to continuously deliver lubricating oil to the compressor. This design effectively solves the problem of lubricating oil circulation interruption in conventional centrifugal chiller units under emergency conditions, avoids abnormal mechanical wear of the compressor bearings caused by dry friction due to lack of oil, provides reliable protection for the bearings and core components of the compressor, helps the unit operate safely and stably, and significantly extends the unit's service life.

Description

Technical Field

[0001] This application relates to the field of water chillers, and more particularly to a water chiller. Background Technology

[0002] In centrifugal chillers, lubricating oil plays a crucial role in ensuring the safe and stable operation of the unit. Its main functions include: effectively reducing the frictional resistance of the compressor shaft, ensuring smooth operation; promptly removing heat generated by the bearings during chiller operation, achieving cooling and temperature control of the compressor bearings; and simultaneously forming a sufficiently thick oil film between moving parts, achieving complete isolation of metal components (especially bearings), thereby significantly reducing contact wear and preventing corrosion of metal surfaces. Therefore, lubricating oil provides comprehensive protection for the bearings during chiller operation.

[0003] In conventional centrifugal chillers, lubricating oil circulation relies on the pressure differential established by the oil pump. When the oil pump is running, the lubricating oil flows continuously, lubricating the bearings and carrying away heat. However, when the chiller experiences a sudden power outage or the oil pump malfunctions, the pressure differential established by the oil pump will quickly disappear, causing the lubricating oil circulation to be interrupted. At this time, the compressor cannot stop running immediately due to inertia, and the bearings are still rotating at high speed. If there is a lack of continuous lubricating oil supply, the bearings will inevitably be in a state of dry friction, which will lead to abnormal mechanical wear (such as "shaft friction"), seriously damaging the bearings and the core components of the compressor, and greatly shortening the service life of the unit.

[0004] Therefore, in the event of power outages or oil pump failures, maintaining the necessary lubricating oil supply, avoiding damage caused by dry friction of bearings, and ensuring the safety of chiller units have become key technical issues that urgently need to be addressed in this field. Utility Model Content

[0005] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a chiller unit that can solve the above-mentioned technical problems.

[0006] This application provides a chiller unit, including:

[0007] A refrigeration circuit includes an evaporator, a compressor, and a condenser arranged in series.

[0008] An electric oil supply circuit includes at least an oil supply tank, the oil supply tank having a first oil return port, a first oil outlet, and a second oil outlet, the first oil return port being connected to the compressor, the first oil outlet being connected to the compressor, and the electric oil supply circuit being used to electrically circulate and supply lubricating oil to the compressor;

[0009] A pneumatic oil supply circuit includes at least a pneumatic oil pump and a control element. The pneumatic oil pump includes an oil supply line and a pneumatic drive line. The oil supply line has a first inlet and a first outlet. The first inlet is connected to a second outlet, and the first outlet is connected between the first outlet and the compressor. The pneumatic drive line has a second inlet and a second outlet. The second inlet is connected to the condenser, and the second outlet is connected to the evaporator. The control element is disposed on the pneumatic drive line.

[0010] The control element has a first state and a second state. When the electric oil supply circuit is operating normally, the control element is in the first state, blocking the flow of high-pressure gaseous refrigerant to the pneumatic drive pipeline. When the electric oil supply circuit fails, the control element switches to the second state, and the high-pressure gaseous refrigerant in the condenser flows to the evaporator through the pneumatic drive pipeline to drive the pneumatic oil pump to deliver the lubricating oil to the compressor through the oil supply pipeline.

[0011] According to the technical solution provided in the embodiments of this application, the control element is a solenoid valve, and the solenoid valve is disposed between the second outlet and the evaporator.

[0012] According to the technical solution provided in the embodiments of this application, the pneumatic oil supply circuit further includes a first energy storage tank, which is disposed between the condenser and the second inlet, and is used to store the high-pressure gaseous refrigerant output by the condenser.

[0013] According to the technical solution provided in the embodiments of this application, the pneumatic oil supply circuit further includes a first one-way valve, which is disposed between the first energy storage tank and the condenser, and is used to prevent the high-pressure gaseous refrigerant from flowing back.

[0014] According to the technical solution provided in the embodiments of this application, the pneumatic oil supply circuit further includes a second energy storage tank. The second energy storage tank is disposed inside the condenser. One end of the second energy storage tank is connected to the high-pressure side of the condenser, and the other end is connected to the second inlet. The second energy storage tank is used to store the high-pressure gaseous refrigerant in the condenser.

[0015] According to the technical solution provided in the embodiments of this application, a second one-way valve is provided between the high-pressure side of the condenser and the second energy storage tank.

[0016] According to the technical solution provided in the embodiments of this application, the electric oil supply circuit further includes an electric oil pump, which is disposed between the first oil outlet and the first outlet.

[0017] According to the technical solution provided in the embodiments of this application, a first pressure sensor is provided on the oil supply tank, and a second pressure sensor is provided between the first outlet and the compressor. The first pressure sensor is used to collect the pressure in the oil supply tank, and the second pressure sensor is used to collect the pressure at the output end of the electric oil pump.

[0018] The technical solutions provided in this application have the following advantages compared with the prior art:

[0019] This application provides a chiller unit, including a refrigeration circuit, an electric oil supply circuit, and a pneumatic oil supply circuit. The refrigeration circuit includes an evaporator, a compressor, and a condenser connected in series. The pneumatic oil supply circuit is connected in parallel with the electric oil supply circuit. It can be seen that this application, by setting the electric and pneumatic oil supply circuits to work together, allows the electric oil supply circuit to stably supply lubricating oil to the compressor under normal conditions, ensuring the lubrication needs of the unit during normal operation. When the electric oil supply circuit malfunctions due to sudden power outages, oil pump failures, or other situations, the control element switches to a second state, using the high-pressure gaseous refrigerant in the condenser to drive the pneumatic oil pump through the pneumatic drive pipeline to continuously supply lubricating oil to the compressor. This design effectively solves the problem of lubricating oil circulation interruption in conventional centrifugal chillers under emergency conditions, avoids abnormal mechanical wear of the compressor bearings caused by dry friction due to lack of oil, provides reliable protection for the bearings and core components of the compressor, helps the unit operate safely and stably, and significantly extends the unit's service life. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0023] Figure 1 A schematic diagram of a chiller unit provided in Embodiment 1 of this application;

[0024] Figure 2The principle of a chiller unit with a pressure sensor provided in Embodiment 1 of this application;

[0025] Figure 3 This is a schematic diagram of a chiller unit provided in Embodiment 2 of this application.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1. Evaporator; 2. Compressor; 3. Condenser; 4. First check valve; 5. First energy storage tank; 6. Pneumatic oil pump; 7. Solenoid valve; 8. Electric oil pump; 9. First pressure sensor; 10. Second pressure sensor; 11. Oil supply tank; 12. Second energy storage tank; 13. Second check valve. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0030] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can 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 in the text will be interpreted accordingly.

[0031] Example 1

[0032] Please refer to Figures 1-2 This application provides a water chiller unit, comprising:

[0033] The refrigeration circuit includes an evaporator 1, a compressor 2, and a condenser 3 arranged in series.

[0034] The electric oil supply circuit includes at least an oil supply tank 11. The oil supply tank 11 has a first oil return port, a first oil outlet port and a second oil outlet port. The first oil return port is connected to the compressor 2 and the first oil outlet port is connected to the compressor 2. The electric oil supply circuit is used to provide lubricating oil to the compressor 2 in an electric cycle.

[0035] The pneumatic oil supply circuit includes at least a pneumatic oil pump 6 and a control element. The pneumatic oil pump 6 includes an oil supply line and a pneumatic drive line. The oil supply line has a first inlet and a first outlet. The first inlet is connected to a second outlet, and the first outlet is connected between the first outlet and the compressor 2. The pneumatic drive line has a second inlet and a second outlet. The second inlet is connected to the condenser 3, and the second outlet is connected to the evaporator 1. The control element is disposed on the pneumatic drive line.

[0036] The control element has a first state and a second state. When the electric oil supply circuit is running normally, the control element is in the first state, blocking the flow of high-pressure gaseous refrigerant to the pneumatic drive pipeline. When the electric oil supply circuit fails, the control element switches to the second state, and the high-pressure gaseous refrigerant in the condenser 3 flows to the evaporator 1 through the pneumatic drive pipeline to drive the pneumatic oil pump 6 to deliver lubricating oil to the compressor 2 through the oil supply pipeline.

[0037] Specifically, such as Figure 1As shown, in the refrigeration circuit, refrigerant circulates between the evaporator 1, compressor 2, and condenser 3. The refrigerant circulation follows the vapor compression refrigeration principle: the low-temperature, low-pressure liquid refrigerant absorbs heat from the refrigerant in the evaporator 1 and vaporizes into a low-pressure gaseous refrigerant; this low-pressure gaseous refrigerant is drawn into the compressor 2 and compressed into a high-pressure gaseous refrigerant. Subsequently, the high-pressure gaseous refrigerant enters the condenser 3, releases heat to the external environment, and condenses into a high-pressure liquid refrigerant. After throttling and depressurization, the refrigerant becomes a low-temperature, low-pressure liquid-gas mixture again and returns to the evaporator 1, thus completing a continuous refrigeration cycle and realizing the directional transfer of heat from the evaporator 1 side to the condenser 3 side.

[0038] Specifically, in this embodiment, the electric oil supply circuit includes at least an oil supply tank 11, which has a first oil return port, a first oil outlet, and a second oil outlet. The first oil return port and the first oil outlet are both connected to the compressor 2 to form the main circulation channel for lubricating oil. When the chiller unit is running, the lubricating oil in the oil supply tank 11 enters the high-level oil tank of the compressor 2 and then flows into the bearing position of the compressor 2. The lubricating oil lubricates the bearing and carries away the heat generated by the bearing before returning to the oil supply tank 11 through the first oil return port to complete the oil supply cycle.

[0039] Specifically, in this embodiment, the pneumatic oil supply circuit serves as a backup circulation channel and includes at least a pneumatic oil pump 6 and a control element. The pneumatic oil pump 6 includes a parallel oil supply pipeline and a pneumatic drive pipeline. The first inlet of the oil supply pipeline is connected to the second oil outlet, and the first outlet is connected between the first oil outlet pipeline and the compressor 2. The second inlet of the pneumatic drive pipeline is connected to the high-pressure side of the condenser 3, and the second outlet is connected to the low-pressure side of the evaporator 1 via the control element. The control element has a first state and a second state. When the electric oil supply circuit is operating normally, the control element is in the first state, i.e., the blocking state, which blocks the flow of high-pressure gaseous refrigerant to the pneumatic drive pipeline. When the electric oil supply circuit fails, the control element switches to the second state, i.e., the conducting state, allowing the high-pressure gaseous refrigerant in the condenser 3 to flow to the evaporator 1 via the pneumatic drive pipeline. The system pressure difference drives the pneumatic oil pump 6 to work, continuously delivering lubricating oil to the compressor 2 to ensure uninterrupted bearing lubrication.

[0040] Working Principle: This application sets up an electric oil supply circuit and a pneumatic oil supply circuit to work together. Under normal conditions, the electric oil supply circuit can stably provide lubricating oil to the compressor 2, ensuring the lubrication needs during normal operation of the unit. When the electric oil supply circuit fails due to sudden power outages, oil pump malfunctions, or other reasons, the control element switches to the second state. With the help of the high-pressure gaseous refrigerant in the condenser 3, the pneumatic oil pump 6 is driven through the pneumatic drive pipeline to continuously deliver lubricating oil to the compressor 2. This design effectively solves the problem of lubricating oil circulation interruption in conventional centrifugal chillers under emergency conditions, avoids abnormal mechanical wear caused by dry friction due to lack of oil in the compressor 2 bearings, provides reliable protection for the bearings and core components of the compressor 2, helps the unit operate safely and stably, and significantly extends the service life of the unit.

[0041] In some embodiments, the control element is a solenoid valve 7, which is located between the second outlet and the evaporator 1.

[0042] Specifically, in this embodiment, the control element is in the form of a solenoid valve 7, and the solenoid valve 7 is located on the pipeline between the second outlet of the pneumatic drive pipeline and the evaporator 1; in this embodiment, the solenoid valve 7 is a normally closed solenoid valve.

[0043] When the electric oil supply circuit is working normally, solenoid valve 7 is in the closed state, blocking the flow path of high-pressure gaseous refrigerant in the pneumatic drive pipeline and preventing unnecessary start-up of pneumatic oil pump 6. When the chiller unit suddenly loses power, electric oil pump 8 stops working due to the power failure, and the chiller unit generates a power failure signal. Upon receiving the power failure signal, solenoid valve 7 opens, connecting the pneumatic drive pipeline. Since the evaporator 1 is a low-pressure chamber, the high-pressure gaseous refrigerant in condenser 3 will flow towards the evaporator 1 along the pneumatic drive pipeline due to the pressure difference, utilizing the driving force generated by the flow of high-pressure gaseous refrigerant. The pneumatic oil pump 6 is driven to operate, delivering the lubricating oil in the oil supply tank 11 to the compressor 2 through the oil supply pipeline. This ensures that the compressor 2 can still receive continuous lubrication under fault conditions, preventing dry friction problems in the bearings. This design further refines the working logic of the pneumatic oil supply circuit by specifying the specific form and installation position of the solenoid valve 7, improving the reliability and accuracy of the emergency oil supply mechanism. From a structural perspective, it strengthens the chiller unit's ability to cope with electric oil supply circuit failures, ensuring that the compressor 2 can receive effective lubrication protection under various operating conditions, and contributing to the stable operation of the unit.

[0044] In some embodiments, the pneumatic oil supply circuit further includes a first energy storage tank 5, which is disposed between the condenser 3 and the second inlet. The first energy storage tank 5 is used to store the high-pressure gaseous refrigerant output from the condenser 3.

[0045] Specifically, a first energy storage tank 5 is installed between the second inlet of the pneumatic drive pipeline and the high-pressure side of the condenser 3. Its core function is to store the high-pressure gaseous refrigerant output from the condenser 3. When the electric oil supply circuit is in normal operation, the solenoid valve 7 is in the closed state. At this time, some of the high-pressure gaseous refrigerant in the condenser 3 flows into the first energy storage tank 5 to complete the pre-storage of energy. When the electric oil supply circuit fails, the solenoid valve 7 switches to the conducting state to connect the pneumatic drive pipeline. Since the evaporator 1 is a low-pressure chamber, the high-pressure gaseous refrigerant stored in the first energy storage tank 5 will flow to the evaporator 1 along the pneumatic drive pipeline due to the pressure difference. The driving force generated by the flow of high-pressure gaseous refrigerant drives the pneumatic oil pump 6 to operate, and delivers the lubricating oil in the oil supply tank 11 to the compressor 2 through the oil supply pipeline, ensuring that the compressor 2 can still obtain continuous lubrication under fault conditions and preventing dry friction problems in the bearings.

[0046] In some embodiments, the pneumatic oil supply circuit also includes a first check valve 4, which is disposed between the first energy storage tank 5 and the condenser 3, and is used to prevent backflow of high-pressure gaseous refrigerant.

[0047] Specifically, in this embodiment, the pneumatic oil supply circuit also includes a first one-way valve 4, which is installed on the connecting pipeline between the first energy storage tank 5 and the condenser 3. Its function is to strictly control the flow direction of the high-pressure gaseous refrigerant by utilizing its one-way conduction characteristic, allowing only the high-pressure gaseous refrigerant output from the condenser 3 to flow into the first energy storage tank 5 in one direction. This can effectively avoid the problem of high-pressure gaseous refrigerant flowing back from the first energy storage tank 5 to the condenser 3 due to system pressure fluctuations, ensuring the stable storage function of the first energy storage tank 5 for the high-pressure gaseous refrigerant. This ensures that when the electric oil supply circuit fails and the pneumatic oil supply needs to be activated, the first energy storage tank 5 can reliably release the stored refrigerant to provide continuous driving force for the pneumatic oil pump 6, thereby stably and efficiently delivering lubricating oil to the compressor 2, improving the reliability and stability of the pneumatic oil supply circuit, and helping to improve the lubrication guarantee mechanism of the chiller unit under emergency conditions.

[0048] In some embodiments, the electric oil supply circuit also includes an electric oil pump 8, which is disposed between the first oil outlet and the first outlet.

[0049] Specifically, the electric oil supply circuit includes an electric oil pump 8, which is connected to the pipeline between the first oil outlet and the first outlet. It is used to provide power support for the circulation of lubricating oil in the electric oil supply circuit, and drive the lubricating oil from the oil supply tank 11 through the electric oil pump 8 and the first oil outlet to the compressor 2. This ensures a stable and continuous lubrication supply to the compressor 2 in the electric oil supply mode, enhances the active oil delivery capability of the electric oil supply circuit, and adapts to the lubrication needs of the unit during normal operation.

[0050] In some embodiments, a first pressure sensor 9 is provided on the oil supply tank 11, and a second pressure sensor 10 is provided between the first outlet and the compressor 2. The first pressure sensor 9 is used to collect the pressure inside the oil supply tank 11, and the second pressure sensor 10 is used to collect the pressure at the output end of the electric oil pump 8.

[0051] Specifically, such as Figure 2 As shown, a first pressure sensor 9 is installed on the oil supply tank 11, and a second pressure sensor 10 is installed between the first outlet and the compressor 2. The first pressure sensor 9 is used to collect the pressure in the oil supply tank 11, which is recorded as the first pressure value P1. The second pressure sensor 10 is used to collect the pressure at the output end of the electric oil pump 8, which is recorded as the second pressure value P2. By calculating the pressure difference between the second pressure value P2 and the first pressure value P1, the pressure changes at the inlet and outlet of the electric oil pump 8 can be reflected in real time. When the chiller unit is in normal operation without power interruption, but the electric oil pump 8 is damaged, this pressure difference monitoring mechanism can play a protective role: if an abnormal pressure difference is detected between the inlet and outlet of the electric oil pump 8, such as the pressure difference approaching 0, it is determined that the electric oil pump 8 is faulty. At this time, the chiller unit will automatically send a control signal to instruct the solenoid valve 7 to open and switch to the working mode of the pneumatic oil pump 6 to continuously supply lubricating oil to the compressor 2, ensuring the lubrication needs of the key components of the unit.

[0052] Example 2

[0053] Please refer to Figure 3 A schematic diagram of a chiller unit is provided. The similarities between this embodiment and Embodiment 1 will not be repeated here; the differences are as follows:

[0054] The pneumatic oil supply circuit also includes a second energy storage tank 12, which is located inside the condenser 3. One end of the second energy storage tank 12 is connected to the high-pressure side of the condenser 3, and the other end is connected to the second inlet. The second energy storage tank 12 is used to store the high-pressure gaseous refrigerant in the condenser 3.

[0055] Specifically, such as Figure 3 As shown, the second energy storage tank 12 is located inside the cavity of the condenser 3, so that the condenser 3 and the second energy storage tank 12 are integrated, thereby reducing space occupation and saving the external space of the whole machine.

[0056] In some embodiments, a second check valve 13 is provided between the high-pressure side of the condenser 3 and the second energy storage tank 12.

[0057] Specifically, in this embodiment, a second one-way valve 13 is provided between the high-pressure side of the condenser 3 and the second energy storage tank 12. Its function is to strictly control the flow direction of the high-pressure gaseous refrigerant by utilizing its one-way conduction characteristic. Only a portion of the high-pressure gaseous refrigerant output from the high-pressure side of the condenser 3 is allowed to flow into the second energy storage tank 12 in one direction. This can effectively avoid the problem of high-pressure gaseous refrigerant flowing back from the second energy storage tank 12 into the cavity of the condenser 3 due to system pressure fluctuations, etc. This ensures the stable storage function of the second energy storage tank 12 for high-pressure gaseous refrigerant. It also ensures that when the electric oil supply circuit fails and the pneumatic oil supply needs to be activated, the second energy storage tank 12 can reliably release the stored refrigerant to provide continuous driving force for the pneumatic oil pump 6, thereby stably and efficiently delivering lubricating oil to the compressor 2. This improves the reliability and stability of the pneumatic oil supply circuit and helps to improve the lubrication guarantee mechanism of the chiller unit under emergency conditions.

[0058] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0059] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0060] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A water chiller, characterized by, include: The refrigeration circuit includes an evaporator (1), a compressor (2), and a condenser (3) arranged in series. The electric oil supply circuit includes at least an oil supply tank (11), the oil supply tank (11) having a first oil return port, a first oil outlet and a second oil outlet, the first oil return port being connected to the compressor (2), the first oil outlet being connected to the compressor (2), and the electric oil supply circuit being used to provide lubricating oil to the compressor (2) in an electric circulation. The pneumatic oil supply circuit includes at least a pneumatic oil pump (6) and a control element. The pneumatic oil pump (6) includes an oil supply line and a pneumatic drive line. The oil supply line has a first inlet and a first outlet. The first inlet is connected to a second oil outlet, and the first outlet is connected between the first oil outlet and the compressor (2). The pneumatic drive line has a second inlet and a second outlet. The second inlet is connected to the condenser (3), and the second outlet is connected to the evaporator (1). The control element is disposed on the pneumatic drive line. The control element has a first state and a second state. When the electric oil supply circuit is operating normally, the control element is in the first state, blocking the flow of high-pressure gaseous refrigerant to the pneumatic drive pipeline. When the electric oil supply circuit fails, the control element switches to the second state, and the high-pressure gaseous refrigerant in the condenser (3) flows to the evaporator (1) through the pneumatic drive pipeline to drive the pneumatic oil pump (6) to deliver the lubricating oil to the compressor (2) through the oil supply pipeline.

2. A water chiller as recited in claim 1, wherein The control element is a solenoid valve (7), which is located between the second outlet and the evaporator (1).

3. A water chiller as recited in claim 2, wherein The pneumatic oil supply circuit also includes a first energy storage tank (5), which is located between the condenser (3) and the second inlet. The first energy storage tank (5) is used to store the high-pressure gaseous refrigerant output by the condenser (3).

4. A water chiller as recited in claim 3, wherein The pneumatic oil supply circuit also includes a first check valve (4), which is located between the first energy storage tank (5) and the condenser (3). The first check valve (4) is used to prevent the high-pressure gaseous refrigerant from flowing back.

5. A water chiller as recited in claim 2, wherein The pneumatic oil supply circuit also includes a second energy storage tank (12), which is located inside the condenser (3). One end of the second energy storage tank (12) is connected to the high-pressure side of the condenser (3), and the other end is connected to the second inlet. The second energy storage tank (12) is used to store the high-pressure gaseous refrigerant in the condenser (3).

6. A water chiller as recited in claim 5, wherein A second check valve (13) is provided between the high-pressure side of the condenser (3) and the second energy storage tank (12).

7. A water chiller as recited in claim 1, wherein The electric oil supply circuit also includes an electric oil pump (8), which is located between the first oil outlet and the first outlet.

8. A water chiller as recited in claim 7, wherein A first pressure sensor (9) is provided on the oil supply tank (11), and a second pressure sensor (10) is provided between the first outlet and the compressor (2). The first pressure sensor (9) is used to collect the pressure in the oil supply tank (11), and the second pressure sensor (10) is used to collect the pressure at the output end of the electric oil pump (8).

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